In the present work, molecular dynamics simulations were used to investigate the impact of the tool microstructure on the wear behavior of ferrite workpiece during nanoscratching. The tool microstructure was modified by varying the carbide (cementite) contents. The simulation results show that dislocations are the primary mechanism for plastic deformation of the workpiece material. It is found that total dislocation length varies significantly depending on the carbide content in the tool. Furthermore, other tribological phenomena were also observed to depend on the carbide contents. For example, the average value of frictional forces decreased while the normal force increases with increasing carbide contents, and hence the friction coefficient was decreased. Additionally, the shape and size of lateral and frontal pileups are lowered. The structural analysis of the pileup region reveals the loss of long range order and start of amorphisation. The temperature distribution of the pileup regions showed an increase of the pileup temperature when carbide is added into tool. The wear volume is considerably reduced when the carbide content increases. The average scratch hardness was found to decrease and the result was analyzed with the theoretical Taylor hardening model.
- In sheet metal forming operations, adhesive wear is the main causeof tool damage as sheet material is transferred to the tool surface during the forming operation. Means of reducing adhesive wear are of high interest for the metal forming industry.In the present work, molecular dynamics simulations were used to investigate influence of alloying iron with vanadium on adhesive properties in contact with iron. The results showed that adhesion, quantified by the work of adhesion, decreased as the vanadium content increased. Highest reduction was obtained for 10 at.% vanadium which corresponded to a decrease in adhesive work of approximately 10%.
Molecular dynamics simulations are applied to investigate the wear/friction behavior of a ferrite/austenite iron bi-crystal, as a model system for duplex stainless steels. The plasticity of the ferrite phase is dominated by dislocations while both dislocations and stacking faults are the primary cause of plastic deformation of the austenite phase. Interestingly, the responses of tribological parameters vary depending on the scratch direction. For instance, the scratch hardness is increased by about 46% whereas the friction coefficient is reduced by about 22% when scratch starts from austenite to ferrite. At the interface, a local softening/hardening occurs because of dislocation-interface interaction. The present results demonstrate that martensitic phase transformation is responsible for experimentally observed high amount of ferrite of the pile-up.
Genomförbarheten av Project Support (PS), ett individuellt föräldrastöd för våldsutsatta mammor utvecklat i USA, utvärderas inom ramen för svensk socialtjänst i denna studie. Sammanlagt trettio behandlare har utbildats i metoden, som anpassats till svenska förhållanden i samarbete med upphovsmännen. Tjugonio familjer hade inkluderats i behandling vid sttudiens avslut. Såväl behandlare som mammor uppskattade metoden och bedömde att den var en lämplig insats som förbättrade föräldrarnas samspel med sina barn. Mammornas självskattade föräldraförmåga förbättrades signifikant, och barnens symtomnivåer sänktes. Vissa svårigheter för implementering identifierades, dels metodspecifika, dels relaterade till omständigheter i socialtjänsten.
Intimate partner violence (IPV) constitutes a hidden health risk for exposed mothers and children. In Sweden, screening for IPV in healthcare has only been routine during pregnancy, despite an increase in IPV following childbirth. The arguments against routine questions postpartum have concerned a lack of evidence of beneficial effects as well as fear of stigmatizing women or placing abused women at further risk. Increased understanding of women’s attitudes to routine questions may allay these fears. In this study, 198 mothers in 12 child healthcare centres (CHCs) filled in a short questionnaire about their exposure and received information on IPV at a regular baby check-up visit. The mothers’ lifetime prevalence of exposure to IPV was 16%. One hundred and twenty-eight mothers participated in a telephone interview, giving their opinion on the screening experience. The intervention was well-received by most of the mothers who reported that questions and information on IPV are essential for parents, considering the health risks for children, and that the CHC is a natural arena for this. Necessary prerequisites were that questioning be routine to avoid stigmatizing and be offered in privacy without the partner being present.