As polymer parts are made by injection molding, most defects are usually caused by the shrinkage of material during solidification. These defects are then source of cracks in these parts. Present contribution is dealing with central cracked compression loaded polymer cylinder. In order to describe crack behavior under operational load, parametrical finite element model was developed. As results of this study stress intensity factors for central crack with different crack lengths are determined to describe crack behavior.

The problem of crack propagation from internal defects in thermoplastic cylindrical bearing elements is addressed in this paper. The crack propagation in these elements takes place under mixed-mode conditions—i.e., all three possible loading modes (tensile opening mode I and shear opening modes II and III) of the crack are combined together. Moreover, their mutual relation changes during the rotation of the element. The dependency of the stress intensity factors on the crack length was described by general parametric equations. The model was then modified by adding a void to simulate the presence of a manufacturing defect. It was found that the influence of the void on the stress intensity factor values is quite high, but it fades with crack propagating further from the void. The effect of the friction between the crack faces was find negligible on stress intensity factor values. The results presented in this paper can be directly used for the calculation of bearing elements lifetime without complicated finite element simulations.

This paper aims to investigate the impact of braking with brake blocks on the fatigue lifetime of the train wheel web. Braking generates heat, causing uneven thermal stress and residual stresses as it cools. This can lead to the initiation of fatigue cracks in the wheel web. Therefore, the main issue is the numerical modelling of the railway wheel loaded by mechanical and thermal loads. A complex fatigue investigation is proposed to validate the numerical models and determine critical areas of the wheel web where fatigue cracks can initiate.