Reijo Kouhia

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Most materials exhibit rate-dependent inelastic behaviour. Increasing strain-rate usually increases the yield stress thus enlarging the elastic range. However, the ductility is gradually lost, and for some materials there exist a rather sharp transition strain-rate after which the material behaviour is completely brittle. In this paper, a simple(More)
The solution of linear systems arising in the ®nite element analysis of shells and solids by the preconditioned conjugate gradient method is considered. Stabilized and block versions of the AINV factorized approximate inverse preconditioner are presented and tested on a variety of dicult problems. Comparisons with other preconditioning methods are also(More)
Over 90% of hip fractures are caused by falls. Due to a fall-induced impact on the greater trochanter, the posterior part of the thin superolateral cortex of the femoral neck is known to experience the highest stress, making it a fracture-prone region. Cortical geometry of the proximal femur, in turn, reflects a mechanically appropriate form with respect to(More)
This paper presents a coupled magnetoelastic model for isotropic ferromagnetic materials used in electrical machines. As proposed by Dorfmann et al. for general nonlinear magnetoelastic solids, the constitutive equations of the model are written on the basis of the Helmholtz free energy for which the strain tensor and the magnetic induction vector are(More)
A new low order membrane nite element is presented. The element formulation is based on the variational principle of Hughes and Brezzi employing an independent rotation eld. In the present work nonconforming interpolation is used for the drill rotation eld. Both triangular and quadrilateral elements are considered. Combined with the Reissner-Mindlin plate(More)
Non-linear eigenproblems can be encountered in a wide range of physical systems, stability analysis being an important source of such problems. The current technique used in commercial finite element codes to solve non-linear eigenproblems consists in linearizing the criticality equation with respect to the bifurcation parameter evaluated at the origin.(More)