The ALE-method with triangular elements: direct convection of integration point values

The arbitrary Lagrangian-Eulerian (ALE) finite element method is applied to the simulation of forming processes where material is highly deformed. Here, the split formulation is used: a Lagrangian step is done with an implicit finite element formulation, followed by an explicit (purely convective) Eulerian step. The purpose of this study is to investigate the Eulerian step for quadratic triangular elements. To solve the convection equation for integration point values, a new method inspired by Van Leer is constructed. The new method is based on direct convection of integration point values without intervention of nodal point values.\ud The Molenkamp test and a so-called block test were executed to check the performance and stability of the convection scheme. From these tests it is concluded that the new convection scheme shows accurate results. The scheme is extended to an ALE-algorithm. An extrusion process was simulated to test the applicability of the scheme to engineering problems. It is concluded that direct convection of integration point values with the presented algorithm leads to accurate results and that it can be applied to ALE-simulation

Modelling of aluminium sheet material at elevated temperatures

The formability of Al–Mg sheet can be improved considerably, by increasing the temperature.\ud At elevated temperatures, the mechanical response of the material becomes strain rate dependent. To accurately\ud simulate warm forming of aluminium sheet, a material model is required that incorporates the temperature\ud and strain-rate dependency. In this paper hardening is described succesfully with a physically based material\ud model for temperatures up to 200 ◦C. At higher temperatures and very low strain rates, the flow curve deviates\ud significantly from the model. Strain rate jumps still pose a serious problem to the model

Illness perceptions of leprosy-cured individuals in Surinam with residual disfigurements – “I am cured, but still I am ill”

Objective Leprosy has rarely been the subject of health psychology research despite its substantial impact. Our aim was to explore illness perceptions in patients and their health care providers in Surinam. The Common Sense Model (CSM) was the guiding theoretical model. Design Patients with biomedically cured leprosy and their health care providers completed the B-IPQ and took part in semi-structured interviews. The literature on illness perceptions in patients with leprosy was reviewed. Main outcome measures Patients’ B-IPQ scores were compared with samples of patients with other (chronic) illnesses, and with health care providers completing the questionnaire as if they were visibly disfigured patients. Quotations from the semi-structured interviews were used to contextualise the illness perceptions. Results Patients’ B-IPQ scores reflected the chronic nature of leprosy and were comparable with those with other chronic illnesses. Health care providers perceived leprosy to have a greater negative impact than did the patients. Perceived understanding of causes differed considerably between patients and health care providers. Conclusion Leprosy continues to be experienced as an illness with major psychological and social consequences such as stigmatisation, even after biomedical cure. Interventions that target patients, health care providers, and society at large may help reduce perceived shame and stigma. The CSM is a helpful theoretical model in studying this population. </jats:sec