This work proposes the complete design cycle for several auxetic materials where the cycle consists of three steps (i) the design of the micro-architecture, (ii) the manufacturing of the material and (iii) the testing of the material. We use topology optimization via a level-set method and asymptotic homogenization to obtain periodic micro-architectured materials with a prescribed effective elasticity tensor and Poisson’s ratio. The space of admissible micro-architectural shapes that carries orthotropic material symmetry allows to attain shapes with an effective Poisson’s ratio below −1−1. Moreover, the specimens were manufactured using a commercial stereolithography Ember printer and are mechanically tested. The observed displacement and strain fields during tensile testing obtained by digital image correlation match the predictions from the finite element simulations and demonstrate the efficiency of the design cycle.

We design the micro-architecture of thin elastic panels to control their macroscopic behavior, accounting simultaneously for in-plane stiffness, out-of-plane stiffness and the extension–bending coupling effects. Our topology optimization method combines inverse homogenization, the Hadamard shape derivative and a level set method in the diffuse interface context to systematically capture within the unit cell the optimal micro-architecture. The efficiency of the solution method is illustrated through four numerical examples where the designed shape yields an important extension–bending coupling. The deformation responses under tensile loading are assessed numerically both on the complete periodic panel and on its homogenized twin plate. The results demonstrate that the simultaneous control of the in-plane, out-of-plane and their coupled behavior enables to shift a flat panel into a dome or a saddle shaped structure. Moreover, the obtained unit cells are elementary blocks to create directly 3D printable objects with shape-morphing capabilities.

The purpose of the study is to demonstrate how children apply simple technology in preschool through “The Big Five”. Observations and "Interview on the move" are the method choices that answer the purpose and questions of the study. Observations and interviews have been conducted in the preschool outdoor environment during a morning and are based on the children's free play where the aim is to start from the children's perspective and reflections. The situations that have been chosen for the study are based on the children's curiosity and demonstrated interests. The result of the study shows that two of “The Big Five” are applied by the children in the preschool outdoor environment and free play. This is demonstrated by their use of the leaning plane and the wheel from “The Big Five”. It shows by their use of tools such as exploration, part of the game and through concepts. This is done through a sociocultural perspective where different factors influence children's learning.

To anchor various structures in the ground, there are currently only a few options available. The most common and readily accessible methods for ground anchoring are either pouring concrete foundations or installing ground screw. While these methods have their advantages and disadvantages, the disadvantages make them unsuitable for quick and easy installation by individual and inexperienced homeowners. The goal was to develop a concept that can complement existing methods, with a focus on securing anchoring in low-strength soil and in soil with higher strength but at shallow depths. Emphasis was placed on user-friendly installation and cost-effective manufacturing. The result is an anchoring system comprised of two nestled brackets, through which several piles are driven into the ground. The pile angle has been determined with calculations on the shear strengths of typical Swedish soils. 

This work has been carried out as a bachelor’s thesis at Karlstad University, commissioned by the company Invencon AB.

This study analyses and examines the hybrid printing process at Uddeholms AB in Hagfors.The objective of this study is to present recommended parameters to achieve optimal printingresults in a newly developed steel as well as a steel powder material designed for additivemanufacturing.The study showed that the best results occurred when printing on metal in a delivery state,with a thin layer thickness and double exposure. This resulted in full density in the fusion zoneand a gradient hardness change compared to a linear hardness change which was achievedwhen using single exposure. This leads to a lower chance of crack initiation due to internalstresses in the material.Additionally, a fixture system is presented that can fixate a variety of geometriessimultaneously. The use of this fixture system leads to a reduction in lead time by up toapproximately 85% comparing to the fixture solution in use today. Another benefit is theincreased economic sustainability since the operator does not need bespoke fixturing solutionsfor specific jobs.To achieve optimal properties of the printed detail, the parameters presented in this studyshould be used in conjunction with the fixture system.

Having smart and autonomous earthmoving in mind, we explore high-performance wheel loading in a simulated environment. This paper introduces a wheel loader simulator that combines contacting 3D multibody dynamics with a hybrid continuum-particle terrain model, supporting realistic digging forces and soil displacements at real-time performance. A total of 270,000 simulations are run with different loading actions, pile slopes, and soil to analyze how they affect the loading performance. The results suggest that the preferred digging actions should preserve and exploit a steep pile slope. High digging speed favors high productivity, while energy-efficient loading requires a lower dig speed. 

Abstract The fracture problem for a medium composed of a cracked piezoelectric strip with functionally graded orthotropic coating is studied. The layer is subjected to anti-plane mechanical and in-plane electrical loading. In this paper, we first address, the problem of a screw dislocation located in a substrate which is imperfectly bonded to the coating. Then, in order to model the cracked piezoelectric layer, by means of the dislocation solution, we construct integral equations for the layer, in which the unknown variables are dislocation densities. These unknowns are determined through satisfaction of the boundary conditions on the crack faces. By use of the dislocation densities, the field intensity factors are determined. Several examples are presented to demonstrate the applicability of the proposed solution. ", keywords = Piezoelectric strip; Functionally graded layer; Imperfect bonding; Multiple cracks; Stress intensity factors, isbn = 0020-7403, doi=https://doi.org/10.1016/j.ijmecsci.2014.11.025

The dynamic behaviors of several moving cracks in a functionally graded piezoelectric (FGP) strip subjected to anti-plane mechanical loading and in-plane electrical loading are investigated. For the first time, the distributed dislocation technique is used to construct the integral equations for FGP materials, in which the unknown variables are the dislocation densities. With the dislocation densities, the field intensity factors are determined. Moreover, the effects of the speed of the crack propagation on the field intensity factors are studied. Several examples are solved, and the numerical results for the stress intensity factor and the electric displacement intensity factor are presented graphically finally.

The stress-deformation relation i.e. cohesive law representing the fracture process in an almost incompressible adhesive tape is measured using the double cantilever beam specimen. As in many ductile materials, the fracture process of the tape involves nucleation, growth and coalesce of cavities. This process is studied carefully by exploiting the transparency of the used materials and the inherent stability of the specimen configuration. Utilising the path independence of the J -integral, the cohesive law is measured. The law is compared to the results of butt-joint tests. The law contains two stress peaks—the first is associated with nucleation of cavities at a stress level conforming to predictions of void nucleation in rubber elasticity. The second stress peak is associated with fracture of stretched walls between fully-grown cavities. After this second peak, a macroscopic crack is formed. The tape suffers at this stage an engineering strain of about 800%. A numerical analysis with the determined cohesive law recreates the global specimen behaviour.

Confined layers may fracture in shear. This occurs, for example in adhesive joints and composite materials. A common mechanism for shear fracture is the formation of shear hackles associated with an expansion of the layer. This makes shear toughness and strength depend on the constraint of the expansion. By constraining the expansion using external loading in experiments, the expansion is reduced but not totally inhibited. The experiments are evaluated using the path independent properties of the J-integral. It is shown that the shear toughness increases for the more constrained case. Thus, from a strength analysis perspective, ignoring the expansion leads to a conservative estimate of the fracture properties. Extrapolation of the evaluated properties to totally inhibited expansions gives the traction separation relation and the fracture toughness for a layer in simple shear.

Using material distribution-based topology optimization, we optimize the bandpass design of a loudspeaker cabinet targeting low frequencies. The objective is to maximize the loudspeaker’s output power for a single frequency as well as a range of frequencies. To model the loudspeaker’s performance, we combine a linear electromechanical transducer model with a computationally efficient hybrid 2D–3D model for sound propagation. The adjoint variable approach computes the gradients of the objective function with respect to the design variables, and the Method of Moving Asymptotes (MMA) solves the topology optimization problem. To manage intermediate values of the material indicator function, a quadratic penalty is added to the objective function, and a non-linear filter is used to obtain a mesh independent design. By carefully selecting the target frequency range, we can guide the optimization algorithm to successfully generate a loudspeaker design with the required bandpass character. To the best of our knowledge, this study constitutes the first successful attempt to design the interior structure of a loudspeaker cabinet using topology optimization.

We consider a non-linear extension of Biot's model for poromechanics, wherein both the fluid flow and mechanical deformation are allowed to be non-linear. Specifically, we study the case when the volumetric stress and the fluid density are non-linear functions satisfying certain assumptions. We perform an implicit discretization in time (backward Euler) and propose two iterative schemes for solving the non-linear problems appearing within each time step: a splitting algorithm extending the undrained split and fixed stress methods to non-linear problems, and a monolithic L-scheme. The convergence of both schemes are shown rigorously. Illustrative numerical examples are presented to confirm the applicability of the schemes and validate the theoretical results.

Cohesive Zone Models with finite thickness are widely used for the fracture mechanical modeling of material layers, e.g., adhesive layers. Within this approach, the whole layer is modeled as a cohesive zone. Moreover, computational homogenization techniques are crucial for the development of advanced engineering materials, which are often heterogeneous. Compared to the commonly used Finite Element Method (FEM), solvers based on the Fast Fourier Transform (FFT) are expected to reduce the computational effort needed for the homogenization. Originated from an existing method for the computational homogenization of cohesive zones using FEM, a novel FFT-based homogenization scheme for cohesive zone models is presented. Our implementation of the FFT solver uses a displacement-based Barzilai–Borwein scheme and a non-local ductile damage model for the fracture behavior. Finally, the practical application of the method is discussed using an adhesive layer and the core material of HybrixTM metal sandwich plates as examples. 

Cohesive Zone Models with finite thickness are widely used for the fracture mechanical modeling of layers of material, e.g., adhesives. Within this approach, the whole layer is modeled as a Cohesive Zone. Moreover, computational homogenization techniques are crucial for the development of advanced engineering materials, which are often heterogeneous. Compared to the classical Finite Element Method (FEM), computationally more efficient solvers based on the Fast Fourier Transform (FFT) are expected to reduce the computational effort needed for the homogenization. Originated from an existing method for the computational homogenization of Cohesive Zones using FEM, a novel FFT-based homogenization scheme for Cohesive Zone Models was developed. Our implementation of the FFT solver uses the Barzilai-Borwein scheme and a non-local ductile damage model for the fracture behavior. Finally, the method is applied to the core material of HybrixTM metal sandwich plates, and the good agreement with experimental results in opening mode I is shown. 

RBS 70 was introduced 1978 in Sweden and developed to be counter threats on the battlefield. This weapon is efficient against both conventional and small targets. Main components of the system are stand, sight and missile in container. RBS 70 NG with three legs is named as MANPADS configuration and has requirements for the natural frequency in launching direction to 4-6 Hz when placing it to a concrete ground.This Master Thesis has focus on vehicle integrate system, which requires legs to be removed from the MANPADS configuration and put it on a platform placed on a vehicle. For the vehicle integrated system 3.5 Hz will be acceptable as the lowest natural frequency. Four different concepts were purposed and evaluated for the mechanical interface between RBS 70 NG system and weapon platform: Existing platform with fix interface between RBS 70 NG system and platform where the thickness of the roof plate is 5 mm (named as reference model). Modified platform with thick plate (thickness of 30 mm) and fix interface between RBS 70 NG system and platform. Existing platform with damped interface between RBS 70 NG system and platform where the thickness of the roof plate is 5 mm. Modified platform with thick plate (thickness of 30 mm) and damped interface between RBS 70 NG system and platform.The final concept should meet the main requirements of SMU (Stabilized Mirror Unit) and simultaneously keep natural frequency for RBS 70 NG system within requirements.A theoretical evaluation of the longitudinal stiffness for the dampers has been calculated in the report and inputted as the value of the dampers in ANSYS R18.1. Modal analysis and harmonic response analysis was performed for all proposed concepts.Magnification ratio calculation for a system without dampers will illustrate that the upcoming amplitude for the 5 mm plate will amplified more than 30 mm plate at coherent frequencies.By studying the results it illustrates that a plate with thickness of 30 mm helps to minimize the disturbance in elevation direction but not in azimuth direction. To minimize the disturbance in all directions concepts with dampers will be a satisfied solution.

UMV är ett företag som konstruerar och tillverkar bestrykningsmaskiner till papper och kartongindustrin. På dessa pappersmaskiner finns det en schaber monterad, som har till uppgift att skrapa av en vals från smuts och bestrykningsmaterial. I dagsläget köps denna schaber in som ett färdigt system, medan många av de resterande delarna till bestrykningsmaskinen konstrueras av UMV och tillverkas av underleverantörer. UMV vill undersöka vad kostnaderna skulle bli om de själva skulle konstruera och tillverka en schaber vilket är orsaken till att detta examensarbete har skapats.

Projektets huvudsakliga målsättning har varit att ta fram ett koncept på en schaber som är billigare än nuvarande inköpta schaber. Konstruktionen har utvecklats mot den kravspecifikation som har tagits fram i arbetet.

Projektet inleddes med att en projektplan och en tidsplan skapades. Sedan undersöktes hur en bestrykningsmaskin fungerar. Vidare undersöktes även valet av lagring för schabern samt materialval. Efter detta steg framställdes olika koncept med hjälp av olika idégenereringsverktyg och ett koncept valdes sedan med hjälp av konceptvalsmatriser. Efter detta steg konstruerades hela schabern i ett CAD-program och ritningar framställdes för alla komponenter. Ritningar skickades sedan till UMV’s lokala leverantör CS produktion för att få offerter och en välgrundad kostnadskalkyl för konceptet. Målet med projektet har uppfyllts och schabern som har konstruerats uppfyller kravspecifikationen samt understiger kostnadskravet.

Welding is a common method for joining of metal or plastic construction parts. This report describes several different weld methods in general terms. The report focuses on the GMAW method, specifically MAG welding.

A case study has also been performed for the company Wenmec. The task received from the company was to compare the mechanical properties of joints welded with the tube electrode called Nittetsu SM-3A and joints welded with the homogenous electrode called ESAB Aristorod 12.63. Both types of weld joint were welded with the MAG method with an Argon based shielding gas with 18% CO_2. The final task of this study is to compare the cost of these electrodes and then help Wenmec to decide which electrode that is the most cost effective.

Tensile testing, impact testing and fatigue testing were performed on the weld joint samples. The hardnesses, microstructures, failure zones and chemical composition were examined with optical microscopy and SEM.

The weld time, the amount of consumed electrode and the weld energy was measured during welding. These properties were similar and the differences between the different joints could be ignored.

Both weld joint types showed similar microstructures and hardnesses. The microstructure was ferrite with carbides or perlite at the grain boundaries. Some silicon oxides were found in the grains.

The yield strength, ultimate tensile strength and cycles to fatigue failure were similar in the two joint types, but the Aristorod weld joint showed higher impact strength and elongation at break.

The chemical composition showed that the SM-3A electrode was a metal cored electrode with some additions of deoxidizing elements and a Copper coating. The Aristorod 12.63 electrode also showed the presence of deoxidizing elements and likely had a Titanium based coating. The sheet metal used as the work pieces are called Ruukki Laser 355 MC and is steel with low Carbon content, some Manganese and some impurities.

The SM-3A electrode was costlier than the 12.63 electrode. This work concluded that the 12.63 electrode was a better alternative for Wenmec due to the lower cost, higher impact strength and higher elongation at break

The finite strain longitudinal free vibration of a rod is studied. Utilizing second Piola-Kirchhoff stress and Green strain tensors, the equation of motion is written in terms of displacement in reference configuration. Three different types of homogenous boundary conditions may be considered for the rod, leading to three nonlinear eigenvalue problems. The series solutions with three terms satisfying the boundary conditions are utilized and the relationships between amplitudes of vibration are obtained by means of the Galerkin method. The backbone curves are drawn and the internal resonance between different modes of vibration is analyzed.

A nonlinear finite strain and velocity gradient framework is formulated for the Euler-€Bernoulli beam theory. This formulation includes finite strain and the strain gradient within the strain energy generalization as well as velocity and its gradient within the kinetic energy generalization. Consequently, static and kinetic internal length scales are developed to capture size effects. The governing equation with initial and boundary conditions is obtained using the variational approach. Free and forced vibration of a simply supported nanobeam is studied for different values of static and kinetic length scales using the method of multiple scales.

The degree of statical indeterminacy is a fundamental property in structural mechanics of discrete truss and beam structures, exploitable in analysis and design. While further specifications, like.e.g. subdivision into an internal and external part or determination w.r.t. special load directions, are well-established, the property is today mainly understood as an integral property of an entire structure (or entire substructures), without quantified information about its distribution in space and w.r.t. load-carrying types. The redundancy matrix, introduced in [1, 2] and extended in [3], provides information about the distribution of statical indeterminacy in discrete truss and beam structures. This gives an additional valuable insight into the load-carrying behavior. In [3] also the redundancy distribution for one-dimensional continua is introduced and computed analogously to the redundancy matrix in discrete truss structures. A generalization of the redundancy concept to spatially continuous, linear, elastostatic representations of structures is given in [4]. The quantity cation of redundancy distribution considering geometrically non-linear behavior is approached in [2, 5]. These works are limited to discrete representations of truss structures with prestressing. We present an extension of the concept of redundancy to beam and surface structures using a  finite element framework. We also discuss ideas on how to consider geometrically non-linear behaviour. There are numerous applications like e.g. robust design of structures, quantification of imperfection sensitivity, evaluation of adaptability, assessment of actuator placement as well as optimal control in adaptive structures.

REFERENCES

[1] Bahndorf, J.: Zur Systematisierung der Seilnetzberechnung und zur Optimierung vonSeilnetzen. Doctoral Thesis, Universitat Stuttgart, Stuttgart, 1991.

[2] Strobel, D.: Die Anwendung der Ausgleichungsrechnung auf elastomechanische Systeme.Doctoral Thesis, Universitat Stuttgart, Stuttgart, 1995.

[3] von Scheven, M., Ramm, E. and Bischoff, M.: Quanti cation of the Redundancy Distributionin Truss and Beam Structures. Int. J. Sol. Str., 2020.

[4] Gade, J., Tkachuk, A., von Scheven, M. and Bischoff, M.: A continuum-mechanical theory of redundancy in elastostatic structures. Int. J. Sol. Str., under review, 2020.

[5] Zhou, J., Chen, W., Zhao, B. and Gao, C.: A uni ed formulation for redundancy of cable-strut structures considering the effect of pre-stresses. Proc. IASS Ann. Symp. 2016, Tokyo, Japan.

In this thesis a model is developed for calculating the loads on the wetclutches in apowershift transmission. This thesis was done at Volvo CE in Eskilstuna and is focusedon their 4-speed countershaft transmissions. The goal of the project is to be able tocalculate the loads automatically during the transmission tests and thus acquire increasedknowledge about what occurs during operation.The model was developed by first generating a number of concepts and then evalu-ating them to decide which one should be developed further. The chosen concept wasthen developed further and implemented into the test equipment as a calculation script.The chosen loads to model were the energy absorbed in each clutch, the coefficient offriction (COF) and the slip distance. The COF was later found to give too unreliableresults to be used in any other way than as a benchmark for how well the model wasconfigured and to see any large changes in COF.The model was validated by calculating the energy absorbed in a HTE-200 seriestransmission and comparing it to a reference calculation model. It was seen that theresults from the new model are very close to the reference result. The energy lostcalculated by the new model will be equal to 94 % of the energy lost calculated by thereference model, but only when measuring the inertia phase. The energy lost is equalto 135 % when the torque phase is included. The increasing difference is believed tobe because of an error in the reference model that means it does not cover the torquephase.

We present a novel class of selective mass scaling (SMS) concepts in the context of explicit dynamic analyses of thin-walled structures using solid elements. The novel SMS schemes are based on the discrete strain gap (DSG) method [1], a method from the field of finite element technology (FET). Thus, they are denoted as DSGSMS schemes and they extend the initial work of [2] for shear deformable structural element formulations to the application in thin solid elements. We show that these novel DSGSMS concepts naturally preserve both translational and rotational inertia and possess high accuracy. Additionally, having non-linear problems including large rotations in mind, we show how efficient isotropic DSGSMS concepts can be developed such that the need for reassembly of scaled mass matrices is avoided. 

As a part of a manufacturing process to produce a kind of steel strip there is a need to guide two strips of steel to the correct position on a revolving drum. It is imperative for the following step in the process that the positioning of the strips are precise. The guidance of the steel strips is currently done by hand. 

The mechanical replacement for the guidance is supposed to operate unattended once the winding process has begun. The aim is that one operator, instead of two as it is done today, will set up the whole machine including the mechanical replacement and then let the winding of the drum be uninterrupted until it is finished. It is important that the winding goes without interruption to reduce the risk of injuries as well as increase productivity. 

During the thesis work a thorough pre-study was done, mainly by communicating with the operators of the winding machine since there was almost no available literature. The pre-study led to a complete specification of the mechanical replacement as well as a few ideas for concepts. Since several of the concepts were dependent on one another, a chain of concept selections were performed to get the best complete concept possible. The complete concept provided the foundation for the layout construction created in Computer Aided Design (CAD).

The new construction is mounted so that it can move in the horizontal plane in order to fulfill the requirements of the production. The guidance is made possible using three separate wheels that are adjustable in two directions. The adjustments to the wheels are made possible by the use of electrically controlled cross sliding tables, that also improve ergonomics for the operator. The most important of the wheels is the 'groove' wheel. The main function of the groove wheel is to guide the underside of both strips to the correct position on the drum, it is placed in the groove of the drum hence the name groove wheel.

The final construction meet all the demands from the initial specification and about half of the optional requirements. Further development of the construction require the FEM analysis to be confirmed and it would also be preferable to produce some sort of prototype to prove the concept of the groove wheel. The prototype is highly important since the groove wheel has a vital role in the product.

At Uddeholm AB, they today use two overhead cranes with chains to move and tilt steel sheets for visual inspection of surface defects. The tilting is done to give the operator a better view of these defects using reflection of light. The problem with this approach is that it is combined with danger of life with hanging load, in case a chain breaks. Therefore Uddeholm AB would like to develop a tilt table that can be mounted on their lift table they use today.

To solve this problem, 5 concepts was developed using a product development process. The chosen concept was further developed into a product that met the defined load case to tilt the sheets, weighing up to 20 tonnes, 55 degrees. The design that was selected use two points of rotation and is driven by three hydraulic cylinders.

The structure has been calculated by hand and with the structural mechanics software Ansys. To tilt the table a complete hydraulic system was developed and dimensioned. The hydraulic system has been calculated by hand and simulated by a computer program called Hopsan developed at Linköping University. 

AbstractThis thesis is the final part of the Innovation and Design Engineering Programme (180 ECTS credits)at the Faculty of Health, Nature and Engineering Science at Karlstad University. The extent of thisthesis is 22.5 ECTS credits and has been performed independently by Hannes Jernberg during thespring of 2013. Metso Paper Karlstad AB is the task maker of this project, and Arvid Johansson is thecompany Representative. Metso Paper Karlstad AB is one of the world leading developer andmanufacturer of tissue paper machines.In the current situation, the company has developed and patented a power management systembased on a Cross Flow Turbine. The current construction is limited to a paper width of 2.9 meters.The company wants to take advantage of all the opportunities provided by the patents, to develop aturbine solution paper machine with a paper width that is wider than 5.5 meters, and give the abilityto manufacture paper for lower energy consumption which is an important part of the production asit is very energy intensive.Problems arise with the increasing length of the turbine, ultimately resulting in that the deflectionbecomes too big and that the momentums, due to the increased torque the turbine blades breaks.By applying the design process, this work has resulted in a number of potential solutions to theproblem. Sketches, LEGO and engineering methodologies have contributed to the good result.The recommended solution generated by this project is to place two regular sized turbines by 2.9meters. The first turbine is placed in its optimal position at the Driver side of the turbine, themomentum provided by the water is leaded by a shaft towards the engine side of the machine. Thesecond turbine is placed directly under the first shaft. This allows the second turbine take care of therest of the water and energy.

The company Falcken Forshaga are manufacturing lifting tools for the steel, paper and concrete industry. The company wants a lifting tool for L-supports which they want to be able to sell to the concrete industry. The reason for this is that todays ways of lifting and rotation of the supports are done by slings which are time consuming to use because the process is done in multiple steps. The reason why the supports are rotated is because they are casted lying down and are transported standing up which means that the supports needs to be lifted and then rotated. The purpose of this project is to simplify the process between casting and transport as well as learn to work on a project at a company. The goal of the work is to design a lifting tool which follows the requirements set by Falcken for the lifting tool and so it can gain CE-mark in the future. To design a lifting tool the product development process was used as it best fits this project. The work started with status analysis to be able to study the steps which occur in the process today from casting to transport. This is today made possible in three steps lift, rotation and movement to make it ready for transportation. A project plan was developed where the project was divided into different parts with goals to always have something to work against which brings the work forward. A risk analysis over the project was constructed at the beginning to analyze potential risks with the aim to minimize them. The biggest risk that was analyzed was that the project will become delayed, to counter this the project plan needs to be up to date as well as to get help if in need. The next step in the process is to list all the specifications and requests from Falcken and summarize them to be able to generate concepts. A second risk analysis was made to analyze the potential risks with or around the lifting tool during lift where the biggest risks is those who involve people getting injured and are the most important to minimize. To generate the concepts the 6-3-5-method was used and resulted in five different concepts which was analyzed further and filtered through an elimination matrix where the best concept was selected. The concept that was chosen and was designed in Autodesk Inventor was a support arm lift which locks in the sides of the L-support and has beams which run along the sides of the support and in underneath the lower edge of the support with plates. The tool is designed to lift in front of the center of gravity of the support which means that when the support is lifted the whole thing will rotate by itself which means that the steps from casting to transport will be done in one step instead of three. To ensure the strength of the construction it is calculated against safety factor of three as well as it is controlled with a FEM-analyze in Creo parametric 5 and inventor 2019 on details with are too complicated to calculate by hand. The tool which was designed meets all the requirement that was set but to achieve a tool which is sellable and is CE-marked more risks must be analyzed according to SS-EN ISO 12100:2010 and its life span has to be calculated via fatigue calculations as well as it must be manufactured and tested.

This report is an examination conducted by Per Jonsson, a student at the University of Karlstad. The examination includes 22.5 credits and it’s a compulsory part in the Bachelor of Science in mechanical Engineering topic.

The company Trollspeed, manufactures high-performance racing engines used by racing teams at the elite level. Big turbochargers and related equipment are assembled together with custom built exhaust manifolds to achieve maximum power output. Together, these parts contribute to a high mass and have to be braced up.     Today’s bracing solotion lead to inevitable tension effects within the manifold that makes cracking occur. This work is about developing a new bracing solution that can handle higher tensions.   The project is divided into two parts. The first part covers the development of a measurement tool for analyzing motion and force effects within the manifold. The development of the gauge resulted in a measurement scale with pointers for the visualization of movements and mounted load cells for analyzing the impact force. This gauge is the basis for the project's second part that covers finding a solution for a new bracing of the manifold.      The selection of strut is based on the measurement results that shows analyzes of motion and force effects. The brace resulted in a M6 turnbuckle.     The installation of this strut is an important element to improve the quality of the manifold. The engine has to be warmed up at least five times before mounting the strut and the manifold weight must be pretensioned using a turnbuckle with ¾ turns turning at that.

Fracture toughness and mechanisms of crack growth are characterized for transparent wood polymer biocomposites and compared to native wood, with the crack normal to the fiber direction (LT fracture plane). Side-grooved specimen geometries generated pure mode I crack growth, whereas previous investigations commonly report 90° crack path deflection. Crack growth micromechanisms were analyzed by experimental fracture tests and in-situ microscopy observations. Large damage zones around the crack tip with fiber bundle bridging and pull-out were observed in the crack wake, justifying more advanced cohesive zone modeling suitable for composite materials design. The polymer matrix resulted in much higher fracture energy of the biocomposites compared to native wood due to increased local cohesive strength. This strength increased from the polymer contribution and more homogeneous stress distribution in the wood fibers. 

Cracks oriented in the toughest direction across the grain of wood (0°) tend to deflect at 90° to the precrack rather than extending in 0° direction. Fracture toughness data across the grain are therefore difficult to interpret. Crack growth mechanisms and effects from replacing wood pore space with a polymer are investigated. Crack growth is analyzed in four-point bending fracture mechanics specimens of birch and two different polymer-filled birch composites using strain-field measurements and finite element analysis (FEA). Calibrated cohesive zone models in both precrack and 90°-directions describe fracture process zone properties in orthotropic FEA-models. Conditions for 0° crack penetration versus 90° crack deflection are analyzed based on cohesive zone properties. Stable, subcritical crack deflection takes place at low load, reduces crack tip stress concentration, and contributes to high structural toughness, provided the 90° toughness is not too low. Polymer-filled neat birch composites have the best structural toughness properties in the present investigation, since 90° toughness is not compromised by any chemical treatment. 

Top hammer drilling is a common method to drill holes in rock formations in mining and civil engineering applications. Failure of drilling machine components has a significant impact on the cost and period of the operation. Internal components of percussive hammers experience extreme loading conditions during their service life. The focus of the present case study is to characterize failure mechanisms of two cylindrical impact pistons subjected to impact loading. The investi-gated components were manufactured from two different steel grades, a surface hardened low alloyed high strength steel and a through hardened cold work tool steel.Failure of both pistons started with degradation of the impact surfaces in term of cavitation erosion and localized surface fatigue phenomena. Subsequently, chipping and removal of material from impact surfaces resulted in formation of semi-spherical holes and craters on both surfaces.Radial and hoop cracks started to develop from cavities on the impact surface. The radial cracks then propagated parallel to the impacting surface in the longitudinal direction of the piston. Once the cracks formed at the impact surface, the damage was controlled by impact fa-tigue. Fatigue beach marks were identified on the fracture surface of failed component.

During the spring semester 2013, the project “Mounting solution for bed lift system“ has  been performed in the course Bachelor’s thesis for degree of Bachelor of Science in Innovation and Design Engineering (MSGC12) at Karlstad’s University. The project was performed in cooperation with ComfortSystem Scandinavia AB, a company that develops and markets products in the area of beds for health care. The aim of the project was to find a new mounting solution for a bed lift system. The product is an adjustable lift that can be applied to an ordinary bed by installing mounting brackets.  The purpose of the project was to develop a mounting solution that would be applicable to a wider range of bed types.  In addition, the solution would also allow an improved applicability of the accessories comprising Comfort System’s assortment, that previously only been applied on health care beds. The company ambition of mounting bed lift and accessories to regular beds is to reach a broader segment of customers, thus increasing the sales.

This project follows the methodology recommended for the product development process. The process is iterative and characterizes problem solving and user customization, and includes life cycle perspective of developing a new product.  The starting-point of the project was to identify customers’ requirements. Interviews were made with four different target groups comprising, technicians, ordinators, caregivers and patients (users). The study about the user was supplemented with analysis in ergonomics, semantics and the environmental impact of products.  Creative methods were used to find solutions. Accordingly, the solutions were evaluated through the assessment of systematic matrixes for decisions, and reconciliations with the employer.

The final selection of the concept consist a gadget for attachment, and a frame for accessories.  The concept is a flexible modular solution that can be used with or without the possibility of mounting accessories. Due to the possible variations of height and width, the module is adapted to fit a broader range of beds. The frame for accessories can be added to the product afterward. The solution is customized, thus it allows for the opportunity to secure different facilities to the bed. With the new solution, the assembly has become both easier and more understandable to implement, because the fact that accessories nowadays can be fixed by a new secure mounting method with measured spaced for accessories. In addition, the solution provides the user with more freedom in designing the bed in the way that fits their personal environment. The new solution for mounting have fewer steps for assembly than previous solution, the ergonomic for technicians who install the product has also been improved. 

To reach a final product, an evaluation and testing of the proposed concept required, thus a prototype must be made. When the project has been completed, the progress and results of the project are to be handed over to the employer at Comfort System.

Eigenstrain offers a versatile generic framework for the description of inelastic deformation that acts as the source of residual stresses. Focused ion beam (FIB) milling used for nanoscale machining is accompanied by target material modification by ion beam damage having residual stress consequences that can be described in terms of eigenstrain. Due to the lack of direct means of experimental determination of residual stress or eigenstrain at the nanoscale we adopt a hybrid approach that consists of eigenstrain abstraction from molecular dynamics simulation, its application within a finite element simulation of a flexible silicon cantilever, and satisfactory comparison of the prediction with experimental observation. Directions for further enquiry are briefly discussed. ", keywords = Focused ion beam milling; Molecular dynamics; Eigenstrain; Residual stress, isbn = 0167-577X, doi=https://doi.org/10.1016/j.matlet.2016.08.111

The question for this work was: How to design and control the guidance of sheet metal molding tool in order to achieve precision over time.The work has been based on the method of product development where the product development is methodically done, individual opinions are eliminated to the greatest possible extent.Several different concepts have been developed, which have since been evaluated in a selection process that has been done by using elimination matrice and criterion weight matrice.A knee joint mechanism has emerged from this selection process. The main advantage of the knee joint mechanism is that it is least affected by the dynamic forces that excite in the molding tools. When the magnitude of the dynamic forces could not be determined, a mechanism emerged that largely eliminates this problem.

This report is the result of a project work carried out at Karlstad University in conjunctionwith the local consulting firm Camatec where most of the work has been performed.The work can be classified as a classic engineering work with supportive theories andcalculations which in this context is relevant.The engineering project has focused on developing new standards for a conveyor that is usedin the Värmland paper industry where large rolls of paper are produced. A conveyor can takeits appearance in many different forms but in this thesis it has been an exemplary look and ithas also become modulatable with a central section, a drive end and a turning end.The construction work has been build under CAD programs such as Pro Engineer, drawingshave been created and costings have been analyzed. Strength calculations have been made andcooperation from several different companies have erected to explore different solutions andideas for a modern and sustainable conveyor.

The goal of this thesis is to design an attachment between a duct and a pod. A pod is what could be compared to an outboard engine for larger vessels. The pod is placed on the outside of the ship’s hull and can rotate 360 ̊. A duct is a large steel ring that can be placed around the propeller on the pod to increasethe propulsion force of the ship in lower velocities. The thesis is written for Rolls Royce AB in Kristinehamn.The demanded requirements of the design are: it must be easy to adapt to different sizes and shapes of pod houses, the duct must be able to bemounted and dismounted from the pod.The result from this thesis is that anupper and a lower attachment weredesigned. The upper attachment consists of two parallel steel plates which arebolted together with a screw plate that is welded to the pod house.The lower attachment is basically a wing with a streamlined profile which is bolted to a stay. Both attachments consist of bolted joints, two guide pins and bursting screws.The design is controlled by parameters in CAD, meaning that if you change the size of the duct the attachments automatically adapts themselves to the new dimensions.The total result from this thesis is a design suggestion and not an actual manufactured product.The design is dimensioned by a load analysis and strength calculations. The dimensions of the bolts are determined by basic load calculation and the guide pins aredimensioned to withstand the shear forces that occur.The conclusion of this thesis is that the developed attachment solution is a good way to solve this problem andthe personal recommendation is that it should be developed further.Further design work that needs to be done with the attachment is a more thorough analysis of the strength and especially with fatigue, since no account has been taken considering fatigue.

This degree project is a verification of a hand made calculation made by Semcon CAE inGothenburg, Sweden. The main purpose has been to investigate how loads in a pre-tensionedbolt appear and how material displacement and contact pressures in the nuts affect bolt joints.A FEM-model has been created to imitate the reality as much as possible this to verifySemcon’s calculations. The result of the FEM-model has been compared with the result fromSemcon report 87-082-008, see appendix 2. Thus the Semcon original report has beenverified.The results between the Semcon report 87-082-008and the FEM calculations can be seen inchapter 2 and appendix 1.The basic data of the degree exam is the Semcon report and is the starting point of the wholeproject. All data regarding dimensions, geometry, materials and so on is based on the datafrom the Semcon report.A fatigue analysis based on the FEM-results was not conducted. This was due to thesimilarities in result between the previous Semcon report and this study

Impact fatigue is an area which very little research has been carried out in. Of interest from companies in the rock drilling industry, Karlstads University has resumed research in the field of impact fatigue. During its experiments, Karlstads University wants to preform experiments with both a solid anvil and a damped anvil. As the damped anvil is a new product this work has followed a typical product development process. In order to be able to evaluate the different solutions, an elimination matrix has been used in connection whit some estimated calculations. The final concept uses a hydraulic cylinder in conjunction with a piston accumulator. As the concept is hydropneumatics and the hydraulic cylinder will need to be modified, there is a potential risk of leakage. The dampening properties of the final concept are enough to be able to perform the work that the client demands. 

Rapporten avser ett examensarbete för Högskoleingenjörsprogrammet i innovationsteknik och design på Karlstads universitet och genomförs våren 2017. Uppdragsgivare för projektet är Support Design AB i Sunne.

Arbetet handlar om att ta fram ett konceptförslag för funktionen som reglerar höjden på kontorsstolen Saga. Stolens gasfjäder bestämmer höjden på stolen och regleras idag med hjälp av en vajerinfästning. Vajerinfästningen medför att stolen endast kan demonteras av en kvalificerad montör och ger upphov till en osäker konstruktion. Projektets huvuduppgift är att kvalitetssäkra mekanismen och förenkla avlägsnande av gasfjäder.

Projektet bygger på en designprocess som inleds med en förstudie. För att säkerställa en god grund till att utveckla ett hållbart konceptförslag undersöks befintliga lösningar på andra kontorsstolar. Förstudien behandlar även: undersökning av befintlig mekanism, kontorsstolsstandarder, hur man konstruerar mot en hållbar konstruktion och undersökning om hur en gasfjäder demonteras från en mekanism. Resultaten från förstudien används till en produktspecifikation. Ifrån den skapas olika koncept som leder fram till ett slutligt konceptval. Det slutliga konceptvalet är ett konceptförslag som ersätter stolsmekanismens vajerinfästning.

Konceptförslaget presenteras med skisser, CAD-konstruktion och komponentlisa. Beräkningar, dimensionering och materialvalsegenskaper presenteras också.

Handling and replacement of cylindrical surface treatment brushes for rolled sheet metal is currently done by hand at the company voestalpine Precision Strip AB in Munkfors. The workis described as time consuming, non-ergonomic and with some risk of personal injuries. The surface treatment brushes that are handled are sensitive to both forces and dirt on their outer jacket area and therefore require caution when handling. To improve the ergonomic circumstances and minimize the risk of personal injury while ensuring the handling of thebrush, the company has requested a lifting tool.

The goal of the project is to develop a travers emounted lifting tool that can lift the brush directly from the delivery pallet and mount in the intended machine without risking the quality of the brush or exposing personnel to risks. The tool is designed to be CE-labeled after manufacturing.

To get a clear picture of today's working methodology and to define problem areas for a brush change, a preliminary study is conducted. The result of this study, together with the wishes of the company, is summarized into a requirement specification that becomes a direct starting point for continued development of the design.

The concepts and ideas that are developed are evaluated and presented to the project organization. Some of the solutions are considered to have potential for further development and are kept for further development. It should be mentioned that the further development of the lifting tool until its final construction is aproduct of partly my own solutions, and partly the viewpoints, ideas and aspects from other members of the project organization.

The final construction of the traverse lifting tool meets the requirements formulated in the specification and is considered safe and easy to handle and with good chances of being CEmarked. The tool can lift the brushes from the delivery pallet, rotate and mount in and out of the machine without grabbing the outer casing area or otherwise risking the brush's functionality. The tool also completely eliminates the non-ergonomic movements that arise as a result of the manual handling of the brushes that occur today.

It is noted that the final lifting tool has potential for improvement, thus it ́s provided suggestions for continued work and further development of the product.

Nowadays all different kind of actuators is used in a widespread range. Their job is to transmit force, bear load, produce linear force, adjust height etc. Hydraulic fluid pressure, pneumatic pressure and electrical current usually change in to some sort of motion in actuators. This report is related to electrical actuators and self-locking problem, which is really common in them. The thesis report has been performed at Reac AB in Åmål, Sweden, a major supplier of wheel chair actuators.

Electrical actuators have vast usage and they are versatile but in some cases they face with different working situation like dynamic forces. Recent generation of electrical actuators which used in wheelchairs (imagine moving wheelchair in bumpy road) have self-locking problem, which it means that they will lose their position after while under compression load. This fact will lead to de-calibration of the control system. Approximately 90% of  AB production is related to the electrical wheelchairs. Challenging point here is dynamic force which can lead to de-calibration of potentiometer and failure of device.

Load capacity of certain actuator (RE25) is 2000 N. In this project different method has been used to simulate and calculate different aspects. Design of new part, material selection and improvement of some parts are most important. During the period lots of static and dynamic tests, CAD design and FEM analysis have been executed.

Shock absorber, lock pin and new material have been run parallel and more or less all those three had a positive effect.

Finally with design and selection of lock pin solution included cogwheel and pin, we overcome to the problem with great results. 

The problem of functionally graded orthotropic half-plane with climb and glide edge dislocations is solved. Dislocations are used as the building blocks of defects to model cracks of modes I and II. Following a dislocation-based approach, the problem is reduced to a system of singular integral equations for dislocation density functions on the surfaces of smooth cracks. These integral equations enforce the crack-face boundary conditions and are solved numerically for the dislocation density. The numerical results include the stress intensity factors for several different cases of crack configurations and arrangements.

Abstract This paper is the sequel of a companion Part I paper devoted to dislocation-based antiplane fracture mechanics within nonlocal and gradient elasticity of bi-Helmholtz type. In the present paper, the inplane analysis is carried out to study cracks of Modes I and II. Generalized continua including nonlocal elasticity of bi-Helmholtz type and gradient elasticity of bi-Helmholtz type (second strain gradient elasticity) offer nonsingular frameworks for the discrete dislocations. Consequently, the dislocation-based fracture mechanics within these frameworks is expected to result in a regularized fracture theory. By distributing the (climb and glide) edge dislocations, (Modes I and II) cracks are modeled. Distinctive features are captured for crack solutions within second-grade theories (nonlocal and gradient elasticity of bi-Helmholtz type) comparing with solutions within first-grade theories (nonlocal and gradient elasticity of Helmholtz type) as well as classical elasticity. Other than the total stress tensor, all of the field quantities are regularized within second-grade theories, while first-grade theories give singular double stress and dislocation density and classical elasticity leads to singularity in the stress field and dislocation density. Similar to gradient elasticity of Helmholtz type (first strain gradient elasticity), crack tip plasticity is captured in gradient elasticity of bi-Helmholtz type without any assumption of the cohesive zone. ", keywords = Crack; Inplane; Dislocation; Nonlocal elasticity of bi-Helmholtz type; Gradient elasticity of bi-Helmholtz type; Nonsingular, isbn = 0020-7683, doi=https://doi.org/10.1016/j.ijsolstr.2016.03.025

Abstract In the present paper, the dislocation-based antiplane fracture mechanics is employed for the analysis of Mode III crack within nonlocal and (strain) gradient elasticity of bi-Helmholtz type. These frameworks are appropriate candidates of generalized continua for regularization of classical singularities of defects such as dislocations. Within nonlocal elasticity of bi-Helmholtz type, nonlocal stress is regularized, while the strain field remain singular. Interestingly, gradient elasticity of bi-Helmholtz type (second strain gradient elasticity) eliminates all physical singularities of discrete dislocation including stress and strain fields and dislocation density while the so-called total stress tensor still contains singularity at the dislocation core. Based on the distribution of dislocations, a fracture theory with nonsingular stress field is formulated in these nonlocal and gradient theories. Strain and displacement fields within nonlocal fracture theory are identical to the classical ones. In contrast, gradient elasticity of bi-Helmholtz type leads to a full nonsingular fracture theory in which stress, strain and dislocation density are regularized. However, the singular total stress of a discrete dislocation results in singular total stress of the plane weakened by a crack. Within classical fracture mechanics, Barenblatt’s cohesive fracture theory assumes that cohesive forces is distributed ahead of the crack tip to model crack tip plasticity and remove the stress singularity. Here, considering the dislocations as the carriers of plasticity, the crack tip plasticity is captured without any assumption. Once the crack is modeled by distributing the dislocations along its surface, due to the gradient theory, the distribution function gives rise to a non-zero plastic distortion ahead of the crack. Consequently, regularized solutions of crack are developed incorporating crack tip plasticity. ", keywords = Crack; Antiplane; Dislocation; Nonlocal elasticity of bi-Helmholtz type; Gradient elasticity of bi-Helmholtz type; Nonsingular, isbn = 0020-7683, doi=https://doi.org/10.1016/j.ijsolstr.2015.10.033

The in-plane classical dislocation-based linear elastic fracture mechanics analysis is extended to the case of strain gradient elasticity. Nonsingular stress and smooth-closure crack profiles are derived. As in the classical treatment, the crack is represented by a distribution of climb edge dislocations (for Mode I) or glide edge dislocations (for mode II). These distributions are determined through the solution of corresponding integral equations based on variationally consistent boundary conditions. An incompatible framework is used and the nonsingular full-field plastic distortion tensor components are calculated. Numerical results and related graphs are provided illustrating the nonsingular behaviour of the stress/strain components and the smooth cusp-like closure of the crack faces at the crack tip. The work provides an alternative approach to celebrated “Barenblatt’s treatment” of cracks, without the introduction of a cohesive zone and related to intermolecular forces ahead of the physical crack tip. It also supplements a recent paper by the authors in which the mode III crack, represented by an array of screw dislocations, was solved within the present gradient elasticity framework.

Stress analysis is carried out in a graded orthotropic layer containing a screw dislocation undergoing time-harmonic deformation. Energy dissipation in the layer is modeled by viscous damping. The stress fields are Cauchy singular at the location of dislocation. The dislocation solution is utilized to derive integral equations for multiple interacting cracks with any location and orientation in the layer. These equations are solved numerically thereby obtaining the dislocation density function on the crack surfaces and stress intensity factors of cracks. The dependencies of stress intensity factors of cracks on the excitation frequency of applied traction and material properties of the layer are investigated. The analysis allows the determination of natural frequencies of a cracked layer. Furthermore, the interactions of two cracks having various configurations are studied.