Evaluation of self-activating temperature influence on cracks initiation in GRP laminates

The paper deals with problems of fatigue processes of GRP laminates under the influence of cyclic loads. An important aspect which takes place in laminate fatigue with polymer matrix is self-activating temperature generated by friction. As it has been shown in previous authors' research, the phenomenon has significant influence on laminate behavior, also, when self-activating temperature comes to glass-transition temperature, which begins transition from elastic to viscoelastic material model. After passing over of this temperature the stiffness decreasing is supervised, that can lead to more quick propagation of faults (especially delaminations) and decreasing of life cycle of composite laminate element. The aim of the presented paper is simulation research of fatigue processes with taking into consideration self-activating temperature and rheology of material. In the research four cases are analyzed, in which layers rotation, self-activating temperature increasing and changes of rheological model were taken into consideration. As the research shows, the self-activating temperature has significant influence on fatigue processes, because it can cause transition of the rheological model of the material. In the future research an experimental verification of the model is planned. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)