Some Aspects of the Application of the Hole Drilling Method on Plastic Materials

Abstract

Residual stresses are always present in nearly every component as a consequence of the manufacturing process. If the material exhibits a crystalline structure, diffraction methods are undoubtedly a method of choice for residual stress analysis. However such a method is not always applicable on plastics. As they undergo complex manufacturing processes, they also have to be evaluated in terms of introduced residual stresses. Here, mechanical methods like the incremental hole drilling method might be more suitable. However, for a reliable residual stress analysis in plastic materials, the hole drilling method usually applied for isotropic metallic materials has to be adapted. A critical point comes from the required strain gauge rosette technique. It involves a stiffening effect due to its assembly and its bonding. Further issues are the stressless introduction of a geometrically defined hole, temperature effects and the viscoelastic behavior of plastic materials. Those critical points were investigated numerically and experimentally on different types of plastic materials in order to improve the hole drilling method and to provide an opportunity to estimate more precisely residual stresses.