Solid mechanics

Experiments and modelling for analysis of 3-D forming of paperboard

Deep-drawing and hydroforming are two methods under consideration for forming of complex shaped paperboard structures for packaging applications.  The objective of this project is to study deformation and damage mechanisms and to develop analysis tools for such 3-D forming techniques.  The Solid Mechanics laboratory within the Odqvist Laboratory has a unique hydroforming device which allows for the manufacturing of 3-D formed paperboard structures and the deep-drawing studies are carried out in cooperation with Dresden University of Technology. In the research work forming experiments using different types of commercial and laboratory materials are combined with finite element modelling of the manufacturing processes.  Recent advances in this thesis work have led to better understanding of the combined effects of moisture and temperature on the elastic-plastic behaviour of paper materials. Understanding of the effects of moisture and temperature is important for 3-D forming processes, because the application of temperature and/or moisture is typically necessary for 3-D forming success.  

Mechanical behaviour and short crack growth of a bearing material: Cooperation between SKF ERC and Solid Mechanics at KTH

The project objective is to determine a unified theory for the material degradation of a high strength bainitic roller bearing steel. In the present work the behaviour of the virgin material was investigated. The idea was to quantify the relevant continuum effects through experiments: monotonic tension and compression, push-pull, cyclic torsion and low temperature creep. Fatigue crack growth experiments were performed on both long and short cracks in order to quantify crack length effects on the growth rate. The material model was implemented in a material subroutine (UMAT in Abaqus) for studying the material model influence on short crack growth predictions. The material model included the strength differential effect, cyclic kinematic and isotropic hardening.