The report intends a thesis work within the machine engineer program at Karlstad University, the employee is Metso Paper Karlstad AB

Metso Paper produces tissue machines for the paper industry and also performs service and development of these products. Tissue is soft paper which includes hygiene paper and table napkins. Focus in the task is to reduce the cost of the reel drum, which is a detailed component in a tissue machine. The reel drum is a drum which is assembled in the end on the paper machine, in the area where the paper is rolled up on spools. The analyzed items have the dimensions; diameter 900mm with the length 2825 mm and diameter1100 mm with the length 5550mm.

Initially, the reel drum’s main functions were analyzed, which can be summarized:

• That with vacuum transport the point (narrow paper chute) from the point swindle groove to the surface between the reel drum and the reel spool

• To support paper during winding on the reel spool

• To create a pressure against the reel spool so that a driven torque arises. The torque is required because the reel spool has no own power supply.

The task was divided in two parts for a simpler procedure,” new structure” and ”improvement and efficiency improvement of existing structure”

New structure treats calculations concerning the thickness of the shell and choices of alternative materials. Improvement and efficiency concerns how the current structure can be simplified and the production process improved. The result demonstrates that today's structure is unnecessary thick, the shell thickness l can be reduced with maintained function properties. To produce the shell in steel instead of cast iron gives lower purchase cost of materials for reel drums in diameter 900mm, buying to shells at the time almost reduces the material cost with 50%

In order to make the existing structure and the production process more effective must certain parts of the casting be carried out with higher precision, criteria such as: thickness, roundness and presence of rest products should be taken into consideration. Higher casting precision makes the following machine work easier.

Finally there exists a big potential to reduce the cost of the reel drum. Important criteria’s that is to be considered are: dimensions, materials and more effective processing.

This report has been written to analyze a newly acquired measurement method within the companyAston Harald Mekaniska Verkstad AB, which is a 3D scanner made by the company Creaform. Thismodel bought has the name Metrascan 3D Black Elite. 3D scanning is an optical measurement methodwhich uses light to create a mesh of a measured object, where it is later compared to a nominal CAD filein the software Polyworks Inspector. To verify this method of measurement, it will be compared to twoother known calibrated and verified methods, which are coordinate measuring machines (CMM) andregular measuring instruments, which includes several kinds of micrometers and general anglemeasuring devices. To analyze and compare these methods an amount of data will be collected, and willbe used to conduct statistical analysis, where the mean/median, normal distribution, standarddeviation, and confidence intervals are included. The report will analyze two different kinds of data,where the first set consists of regular geometries such as linear and circular measurements, as well asseveral kinds of GD&T (Geometric Dimensions and Tolerances). The second set involves more complexgeometries according to the ISO standard ISO 484. The first set of data will be analyzed using amanufactured reference object, made using the aluminum alloy AL-7020 T6. The second set will beanalyzed using a propeller blade borrowed from the company Kongsberg. The results from this reportshow that 3D scanning is not as accurate nor as precise compared to CMM measurement and regularhand measuring instruments and cannot replace these measuring methods entirely. An empiricalformula has been derived from the analyzed data, and tolerance intervals are recommended to beincreased by approximately 0.1 to 1.0 % percent for regular linear and circular measurements dependingon the size of the detail measured. and upwards of 200 percent for GD&T tolerance intervals. However,3D scanning shows a greater promise when it comes to scanning propeller blades, as most measurementpoints were within specification according to the ISO 484 standard, and results can be further improved,such as with a tighter scanning mesh. Quality control and regulation is a topic whose discussion wasdesired, however, due to time constraints and the sensitivity of the scanner equipment, only an FMEAtable of potential error sources has been made for this report. Ergonomically some issues were found,particularly when it comes to static loading of arm muscles and repeated neck movement, both potentialsources for fatigue and injury. Recommended solutions for this include a flexible workstation whereboth the operator and the workpiece can be adjusted for optimal movement with minimal strain onpreviously mentioned body parts. Future improvements include performing a regression analysis ondifferent reference objects with many similar measurement types, for instance 50 holes with differentdiameters, which can lead to direct comparison formulas compared to nominal values. Furthermore,tests can be repeated with eliminating fault sources such as bad lightning.

Our employer Camatec Industriteknik AB gave us the assignments to increase theirs range of versions on Camcoil that is their own patent product. Camcoil is a capstan system that is used when steel band fabricated. Exist for example in production lines their steel band should be annealed. Our goal with this work is to come up with a completed production basis on a Camcoil for heavy industry. The basis should contain calculations, 3D-constructions, drawings and cost proposal on manufacturing and detail purchase.

Demands on this project:

1. 15 ton load

2. Strip width up to 1500 mm

3. Head diameter 610 mm

4. Production speed 35 m/min

5. Economy manufacturing

6. Be simple

Several concepts were decided out of the feasibility study. The concepts were compared against each other and finally only one was left. Result of the design concept became one shaft with three capstan heads and a support function.

One conceivable working process was planed with a Gantt-table. A decision was made that the work of the Camcoil should be separated in several details. Earlier work on Camcoil was study to increase our understanding for the work.

Some of the examined parts were shaft dimensions, bearings, head shape, tripod, support function and hydraulic cylinder for the capstan and support.

Some of the calculations have been made in Ansys. Directional deformation, Von Mises stress for the shaft, length of the hydraulic cylinder in the capstan heads and the stress for tripod and support function was calculated.

Analytic calculations were made on some parts. Frequency analysis for the system was made with Dunkerleys method. The reaction forces in the bearings were calculated with a combination of elementary case. Lifecycle of the bearings can with this be appreciated. Hydraulic cylinder strength in capstan heads and support function, locking assemblies, sheet metal thickness and control off beam dimensions in support was also decided with analytic calculations.

3D models were made on several details in the system. Models like lock rings, engines and bearings were taken from the supplier.

After the modeling assemble drawings and detail drawings were made for the whole capstan system. The drawings were sending to manufacturer for a cost proposal.

Precision är avgörande i väpnade konflikter. Strävan att minimera skador på civila och infrastruktur tillmäts större vikt än någonsin tidigare. Idag finns en teknik som avsevärt förbättrar precisionen på konventionella granater avfyrade från artilleri. Tekniken bygger på att man siktar bortanför målet och bromsar in granaten så att den träffar målet. Innan avfyrning programmeras målets GPS koordinater in i granaten. En inbyggd GPS mottagare i granaten får kontakt med 4-7 satelliter 10-15 sekunder efter avfyrning och bestämmer sin position. En beräkningsalgoritm jämför granatens position med målets position och beräknar bästa möjliga tidpunkt för utfällning av luftbromsen. Den här rapporten behandlar utvecklingen av en sådan broms.

Ett tiotal koncept utvecklades som genomgick en utvärderingsprocess som slutligen resulterade i ett koncept. Det slutgiltiga konceptet designades om för att leva upp till en förutbestämd kravspecifikation. I det slutgiltiga konceptet rör sig fyra stödben med plåtar i radiell riktning. Hela rörelsen sker genom utnyttjande av centrifugalkrafter. I utfällt läge fungerar plåten som luftbroms. Hela konstruktionen ryms i det befintliga tändröret.

För att utvärdera konceptets ur en hållfasthetsmässig synvinkel, göra ett lämpligt materialval samt simulera själva utfällningsförloppet så gjordes flera FEM-analyser i ABAQUS 6.7. Analyserna visade att utfällningsförloppet var möjligt. Som material till plåten valdes ett austenitiskt rostfritt stål vars materialegenskaper är anpassade för att klara utfällningsförloppet och luftlasten i utfällt tillstånd. Slutligen gjordes ett praktiskt prov med lyckat resultat som visade själva utfällningsförloppet

The increasing complexity with the decrease in size of EEE – components (Electronic, electric and electromagnetic) raises the question on how higher energy frequencies will affect the components and their continuous development. The most common vibration testing equipment currently in use within the automotive industry and SCANIA CV AB are the electrodynamic shaker (ED system). This thesis covers the characteristics of different vibration testing equipment while analysing their strengths and weaknesses, not only for the automotive industry but also including equipment more commonly handled within the aero and space industry. The project aims to find a complement for the ED system and study the possibility for its replacement in the automotive industry.In particular, experiments are carried out and documented on a so-called “Repeatable shaker system” (RS system) for the purpose to get a better understanding on the functions of the equipment and its overall differences compared to the electrodynamic system when it comes to random vibration testing.It became clear that complementing or replacing the ED system is difficult and that the RS system work fundamentally different in comparison. Accordingly, the RS system is not a potential replacement for our purpose and it cannot perform at the same level of precision but instead is able to achieve higher energy frequencies overall, making it still ideal for its intended purposes, but not as a replacement of the ED system.

This report contains a degree project made by the mechanical engineering students Lennart Andersson and Daniel Jansson. The project has performed in assignment by SOMAS Valves AB in Säffle. SOMAS are leading in development on control and on/off valves. To maintain this position they always want to improve their products. One way in this development is valves that are more tightened.

The purpose with our project was to investigate another seat design on a HiCo (High Cobalt Alloy) seat to a SKV 150 PN 25 valve and compare this to an original HiCo seat.

By modifying the seat on a ball valve we want to achieve a valve that leaks lesser then a valve whit original seat. At the same time the maneuver torque should be retained or better and the wear should not be worse.

The project begins with a theoretic investigation of valve forces, maneuver torque and seat design. A manufacturing drawing was made in Pro ENGINEER and handed over to SOMAS AB for manufacturing. Four seats are made in the new design and will be compared with four original seats about maneuver torque, tightened and wear. The idea to make a trace in the middle of the seat was that it would tighten earlier.

Water under pressure is pressed against the valve to test its resistance of leaking, the leaking is measured by a measure glass. The modified seats leaks more then the original seats, even though, according to the theory they should have a higher seat force. Even the maneuver torque is higher on the modified seats, but this increase is not a problem. All seats was tested to watch their resistant to wear, to test this, a valve mounted with seats is opened and closed 600 times (about 3hours). Because of the short wear time it’s hard to see and validated wear, but on the after coming pressure test the valve is more tightened.

A reason to leaking is the tolerances between the seats and the ball. The reason why the modified valve seat leaks more is probably that the lathe area functions as a channel for the medium.

The medium which passes the first tightened area can easier find a new way to pass the second tightened area.

The conclusion is that the new seat design is nothing to go further with, but there are proposals for a new seat design.

The project was made in cooperation with Coffee Queen AB, Arvika. The task was to develop and design a new cooler for the milk to Jura Impressa X9, an espresso machine. The good assistance with staff at Coffee Queen and engineers in China and at KPA in Karlstad led to a solution to the problem. It was a long road to get there, many different concepts was developed. When the day came to decide which concept to work with, the choice stood between two different technical solutions. Alt 1: The classic mini-fridge with today’s technique but a new design. Alt 2: Thermos with external cooling and a design which follows the X9. We choice alt 2 because of the fact that part of the production would fit Coffee Queens factory and therefore would it be possible to keep the costs down. The fact that it is a totally new idea in this business made it even more interesting and easier to make a choice. Both design and function is new, which make it interesting to keep working with. In cooperation with engineers in China there will be made a construction so they can make all necessary tests. This will probably happen autumn 2006. The new technique which the group has come up with is that all technique lays external, in a shell made of polypropen, which make it possible to clean the thermos in the dishwasher. Thermos: Vacuum-shaped in stainless steel with bottom of aluminium, covered with a protected surface, that works like a cold plate. Shell made of pp: shape-molding in polypropen and enclose the coolingsystem. This system are Peltiere, where the cooling is generated, spacer block and heat sink, where the heat are led away, and the fan which takes in cold air and blows out warm. The project has become much larger than Coffee Queen expected from the beginning so they will continue this work even after the students have done their share of the project. The new technique is the big question which requires more tests. These tests will carry through as soon as the group has sent all drafts of design and all info that has been gathered during the project. When the factory in China has made a construction of it they will send it to Coffee Queen and the project-group will be contacted to have a chance to take part of these tests.

In the aviation industry the most important factor is safety. GKN are producing the Turbine Exhaust Case (TEC) which is a component in an airplane engine. The welds in an airplane engine are a risk for a breakdown because of fatigue failure due to crack propagation. Since the number of cracks and the size of them are unknown the life expectancy of a TEC is unknown. Instead using deterministic models when calculating the life expectancy one another way is to do the calculations with a probabilistic model. The random variables in the probabilistic model are the number of cracks, size and position of each crack, the variation in materials and the offset between the plates that are welded. By running a Monte-Carlo simulation the probability of failure can be estimated for a specific number of flights. The simulation is validated against a known theoretical case to prove that the method is valid. The aim with the thesis is to have a fast process for as many simulations as possible but the work process is shown to be too slow due to the program that does the crack propagation calculations.

Purpose For anyone digging into the concepts, it becomes obvious that action research and quality management are a really nice match. They share many of their conceptual roots, intentions, core principles/dimensions and processes. Current best practice of quality management can even be understood as doing and strengthening action research processes, in terms of the Plan-do-study-act cycle (PDSA), in organizations. However, the choice, design and application of action research within quality management research is surprisingly seldom discussed or shared. The purpose of this paper is hence to elaborate on how action research and quality management are closely interrelated and how action research can be used more frequently and successfully in quality management research. In addition, the paper hopes to contribute to revitalizing what could be considered the most fundamental practice of quality management: the PDSA cycle.     Method The paper is based on a conceptual discussion combined with illustrative experiences and learnings from several research projects that have applied action research to develop the field of Quality Management. The projects and examples illustrate and share both experiences of dancing at its best and a few uncomfortable falls.   Findings The paper identifies several critical factors to consider when designing and applying action research within quality management research.    Practical Implications As action research is defined by its double aim, developing both scientific knowledge and practice, the ability to successfully design and apply action research in quality management research has large practical implications. One obvious risk if this dance fails is that academic researchers draw back from practice and their ambitions of developing and contributing to practice in their research. The findings of the paper are hoped to increase the number of successful future applications of action research within quality management.   Originality The study provide insights in an area sparsely discussed in previous academic work.

Additive manufacturing (AM) is a quickly rising method of manufacturing due to its ability to increase design freedom. This allows the manufacturing of components not possible by traditional subtractive manufacturing. AM can greatly reduce lead time and material waste, therefore decreasing the cost and environmental impact. The adoption of AM in the aerospace industry requires strict control and predictability of the material deposition to ensure safe flights. 

The method of AM for this thesis is Laser Metal Deposition with wire (LMD-w). Using wire as a feedstock introduces a potential problem, the material transfer from the wire to the substrate. This requires all process parameters to be in balance to produce a stable deposition. The first sign of unbalanced process parameters are the material transfer stabilities; stubbing and dripping. Stubbing occurs when the energy to melt the wire is too low and the wire melts slower than required. Dripping occurs when too much energy is applied and the wire melts earlier than required.  These two reduce the predictability and stability that is required for robust manufacturing. 

Therefore, the use of thermal simulations to predict the material transfer stability for LMD-w using Waspaloy as the deposition material has been studied.  It has been shown that it is possible to predict the material transfer stability using thermal simulations and criterions based on preexisting experimental data.

The criterion for stubbing checks if the completed simulation result produces a wire that ends below the melt pool. For dripping two criterions shows good results, the dilution ratio is a good predictor if the tool elevation remains constant. If there is a change in tool elevation the dimensionless slenderness number is a better predictor. 

Using these predictive criterions it is possible to qualitatively map the process window and better understand the influence of tool elevation and the cross-section of the deposited material.

The project was conducted partly in order to find concepts for an improvement to the current method of sensitivity testing for percussion caps, but also to find concepts for an entirely new method of conducting the tests. A brief statistical evaluation was also conducted to explore the possibility of reducing the number of percussion caps tested without substantially lowering the certainty of the results.

The main workload of the project saw use of a broad product development process primarily utilizing the double diamond methodology. Division of phases was done in accordance with the five-step method where the first part consists of research and an evaluation of the existing method. With this background a requirements specification was produced. Concepts were generated and sorted, and further development was aided by risk analysis' to highlight problems and corrections for the concepts. The statistical part begins by delving into theory related to sample sizes and probability, to then consult internal expertise within the company regarding the current quantity of tests as well as the statistical formula used to evaluate the production batches.

Four concepts for a new test-method were developed, of which one was recommended for further development. The recommended concept uses a spring to store the energy at which the percussion cap is going to be tested and a magazine that allows loading while the machine is continuously performing the test. Design changes such as using a magnetic holder for the weight, introducing a barrier around the base plate and a tilted plane to guide the rolling weight were some of the improvements suggested in order to make the current method less ergonomically demanding and more efficient without significant adjustments. The statistical evaluation found enough cause to support a further study into the reduction of the number of tests by way of performing more tests at certain important energy settings and fewer tests at other energy settings as to maintain the tests statistical significance.

Abstract

Our commissioner Metso Paper Karlstad AB is world leaders in manufacturing Tissue machines (thin paper machine). Metso Paper gave us the commission to develop a Mechanical slitter. A mechanical slitter are being placed in the ending part of a tissue machine and its assignment is to spilt paperboard in to several peaces depending on how many that are installed. The reason by splitting the board is make it fit in the after handling (conversion machine).

The problem with the Slitter today is that it doesn’t satisfy the security demands concerning the ability to use the area around the slitter when it’s in operation mode. The security distance depends on the blade and the distances that it’s not covered. According to EN 294:1992 the safety distance is 850mm. The assignment is present in a demandspecification:

• The Slitter will be constructed considered the security demands to make It possible be around the slitter when its in use.

• Construct for simplified maintenance.

• Coastefficient the sidemovements

• Coastefficient the measurements in sidemovments

• Minimize the price

These demands ended up in following result:

"Pictures"

The distance between the overlaid papersupport and the linscover has now been reduced; it’s only 19mm and will make it possible to use the area around the slitter. According to EN 294:1992 the safety distance now is 120mm. The ability to steer the linscover render possible by steering the engine linear. On today’s model there is only one fixed cover, and the engine is steered from one fixed point and result in a non linearmotion. Concerning the sidemovment and its measurements we decide to buy it all, because today’s components are manufactured by them selves and are really expensive.

Our new construction ended up 15000kr cheaper then today’s siltter and we think it’s a really good result.

Background: Agile methodologies emphasise iterative development, customer collaboration, and flexibility in software development. However, challenges arise when agile practices are adoptedin larger projects. Process inefficiencies and redundancies, knownas process debt, result from the compounded complexities of expanding agile processes and workflows. However, strategies tounderstand and tackle it remain markedly inadequate.Aims: This study investigates process debt types, causes, andeffects in large-scale agile development and its connection withtechnical debt.Method: In this case study, we conducted fifteen semi-structuredinterviews with a Nordic IT company, primarily focusing on telecomrelated products like 5G secure solutions, testing tools, and basestation software. We performed a thematic analysis to examine thedata qualitatively.Results: The thematic analysis identified five process debt typeswith 28 sub-types: documentation (3), roles & responsibilities (5),synchronization (5), inefficiency & unsuitability (12), and infrastructure debt (3) identified causes and effects of process debt andidentified the correlation of process debt to technical debt based ondescriptions from interview data and researchers’ insights.Conclusions: Process debt, stemming from flawed agile practices in large-scale development, causes inefficiencies, reduces quality, and extends timelines, risking technical debt. Its managementis essential for the success of these projects

Denna rapport behandlar hur ett införskaffande av en ny rullformningsmaskin skulle kunna påverka produktionen på ArcelorMittal Construction Sverige AB i Karlstad. Detta är ett examensarbete för högskoleingenjör i maskinteknik vid fakulteten för hälsa, natur- och teknikvetenskap på Karlstads universitet under våren år 2017.

Planerna i dagsläget är att ersätta tre av de nuvarande maskinerna med en ny effektivare maskin som klarar av att tillverka de valda maskinernas olika profiler. Den nya maskinen kan mycket snabbt byta profil från en till en annan. Det tar ca en minut att genomföra ett verktygsbyte med den nya maskinen jämfört med ca 90 minuter i dagsläget för en av de gamla maskinerna.

För att med större säkerhet få reda på nuvarande ställtider genomfördes SMED som är en metod för att reducera ställtider. Arbetet med att reducera ställtiderna visar att med en bättre planering innan stället så kan ställtiden reduceras från 90 minuter till 83 minuter.

Det stora problemet som var gemensamt för alla maskinerna i dagsläget var allt kringarbete som måste utföras, speciellt var det den manuella emballeringen som var den riktiga flaskhalsen i produktionen. Emballeringen utförs av samma operatör som kör maskinen och måste därför med jämna mellanrum avbryta körningen för att få tid att emballera produkten så att de kan placeras i färdigvarulagret för utleverans. Med den nya maskinen är det planerat att ha en helautomatisk emballering för att öka den tid som maskinen är produktiv. 

De nuvarande maskinerna har tillsammans under 2017 producerat plåt med en total verklig hastighet av 10,84 [m/min]. Den nya maskinen måste därför ha en minsta verkliga hastighet på 10,84 [m/min]. Beräkningar av nuvarande genomsnittliga orderstorlekar visar att den nya maskinen klarar minst av att producera med en verklig hastighet på 15,2 [m/min]. Detta medför att den nya maskinen klarar av att ersätta de nuvarande med en god marginal. Den verkliga beräknade hastigheten för den nya maskinen baserat på att coilbyte och profilbyte utförs mellan varje körning, vilket inte är fallet i dagsläget utan flera ordrar med samma form och råmaterial oftast körs efter varandra.

Den nya maskinen medför en förbättring på minst 40 % i verklig hastighet.

ArcelorMittal Construction Sverige AB har i dagsläget ett relativt stort råvarulager för att de snabbt ska kunna leverera den produkt som kunden beställer. Produkter går att få i nästan vilken färg som helst och i flera olika tjocklekar vilket medför att många olika produkter finns i råvarulagret. Fokuset i värdeflödesanalysen har därför varit på en av de mer frekventa råvarorna som passerar genom fabriken. För denna produkt fanns för nuvarande ett lager på 900 ton vilket är en buffert på ca 60 dagar. Då råvaruleveranser kommer dagligen så kan man minska råvarulagret till en buffert på istället 20 dagar och därmed minska det bundna kapitalet som är investerat i dessa råvaror.

Even though vibration measurement is not a new phenomenon, many businesses stillremain sceptical towards the somewhat abstract method. Same scepticism does not existwhen you visit the doctor and he uses his stethoscope to listen after abnormalities inthe sound pattern, even though the similarities are striking. With todays technology it ispossible to diagnose a machine’s different parts in search for damages by analysing theunique vibrationpatterns they provide.

This study aims to close this gap with the help off an introduction to the different termsand choices that exist in vibration analysis as a tool in preventive maintenance and finallyto present guidelines for implementation where economy and availability is consideredmost pivotal for future decisions.

This thesis was carried out at Karlstad University and in corporation with Volvo Car Group, a premium car manufacturer from Sweden. The work focuses on a quality problem at the assembly line. A problem occurs on the front seats with the new generation of XC90 and further released car models. It is to Volvo Cars knowledge that an early wear occurs on the leather seats when assemblers ingress and egress the cars during work tasks and the wear then never recovers. To fix this problem and previous work has been carried out at Research & Development in 2015 but was unfortunately required to be held because of other priorities. The previous work resulted in a prototype which purpose was to become a new test method to this issue. However, the prototype needed further investigation to verify if it can replicate the early wear like the seats at the assembly line.

The goal of the research was to evaluate the prototype with a theory based on Engineering Design Process. A pre-study was performed focusing on collecting data from the previous project, current test methods, leather technology, seat design, benchmarking as well as an excursion of Volvo’s lineup of cars at the assembly line and dealerships. After the pre study, a measurement task was performed with the variety of different seat design. This was done to evaluate whether the prototype met the requested requirements or not. By grading the result with a number between 1-5 it was possible to see a difference between the seat design and to replicate the wear problem. Other attritional wear would occur before the desired outcome of wear, especially on comfort seats. It was hard to apply the sports seat to the benefits of the prototype because of the more advanced design.

The last part consisted of an assessment on the prototype and was based on its performance. The results show that the prototype does have a problem to replicate the wear and isn’t applicable on all available seats. One of the main issues was to get the leather in a brittle state based on the movement from the prototype. Furthermore, a short research was carried out on in-depth knowledge of this work to gain an understanding and cognition for continued work. For replicate the requested wear a pressure movement was required at a 45° angle and aimed to the seat side bolster with a soft polyurethane foam. It shows successfully results at every kind of seat design. To solve this issue it’s necessary for Volvo to consider precautions at the assembly line or changes in seat design with a newly developed test method based on the right premises. 

This paper presents the development of the distributed dislocation dipole technique (DDDT) for the analysis of crack surface closure of crack cases involving kinks and branches. Crack cases in which closure occurs are analyzed by reformulating the Bueckner's principle taking the contact stresses at the contacting portions of the crack surfaces into account. Stress intensity factors corresponding to opening and sliding mode of deformation at the crack tips are computed. Three test cases involving kinked and/or branched cracks with at least one of the crack segments undergoing crack surface closure when subjected to remote tensile loading are analyzed. The results obtained from the DDDT are compared to those obtained from the Finite Element Method (FEM) analysis of the same crack cases. This comparison shows that the computation of stress intensity factors for the crack cases involving crack surface closure are less acurate compared to fully open crack cases. However, the stress intensity factors are still computed to an accuracy of within 2 percent if the Jacobi polynomial expansions of at least the sixth order are used to represent the crack surface opening and sliding displacements. Higher order Jacobi polynomials lead to increased accuracy.

En snabbkopplingstyp för högtryckshydraulik (1000 Bar = 100 MPa) förbättrades med avseende på kulavtryck och låsmekanism. Kopplingen tenderade att ställa sig i halvlåst läge och kopplas ur oavsiktligt. Arbetet inkluderade minskning av kulavtryck i snabbkopplingens nippel samt förhindrande av oavsiktlig urkoppling och halvlåst läge. Geometriska förändringar och materialbyte ledde till dessa förbättringar. Snabbkopplingen är nu optimerad för hertzkontakter och sannolikheten för oavsiktlig urkoppling är mycket låg. Kopplingen är nu säkrare att hantera och är bättre lämpad att ta upp höga kultryck som orsakade kulavtrycken.