Finite element simulations of structures and structural details require suitable material models. Today there is still a lack of such constitutive material models in timber engineering. Therefore, a perennial research project at the Institute for Mechanics of Materials and Structures at the Vienna University of Technology was performed. In this paper the testing equipment, the experiments, the developed material model and its implementation in finite element software will be explained. One focus of the mentioned project is the acquisition of the mechanical behaviour of biaxially, oblique to fibre direction loaded spruce wood. This enables a better simulation of multiaxial stress states in real timber structures. The applicability of the implemented constitutive model will be demonstrated by means of a nonlinear finite element analysis of a bone-shaped test specimen.

This contribution gives an overview about new procedures for the parameter identification for the material characterisation of rubber blends. They are based on a Newton-Raphson procedure and a genetic algorithm. As basis serves an experimental investigation of the viscous properties of rubber blends by means of a capillaryviscometer. Because of simultaneous consideration of wall slippage, temperature and of the die swell, the proposed material characterisation is represented by a coupled system of nonlinear equations. Describing their solutions requires a numerical integration algorithm. For this purpose a generalized Newton-Raphson scheme has been adopted. The verification of the developed parameter identification was done by means of another approach which is based on a genetic algorithm.