Akademik Veri Yönetim Sistemi
Plastics, Rubber and Composites Processing and Applications, cilt.25, sa.3, ss.145-151, 1996 (SCI-Expanded)
Thermal residual stresses in injection mouldings result from the non-uniform cooling of the melt in the mould. Normally, compressive stresses develop at the surface and tensile ones within the core of the mouldings. The magnitude of these residual stresses has been examined for polycarbonate (PC) under various injection moulding conditions. Although the occurrence of thermal stresses is inevitable, warpage results only when the residual stresses are out of balance. The imbalance of the residual stresses is caused by non-uniform temperature distribution through the thickness of the mouldings, which may be caused in part by variation in cross-section, i.e. geometry and in part by a temperature difference between the two surfaces. The magnitude of thermal residual stresses of injection moulded PC flat plaques were determined using a layer removal technique. The development of warpage in a three-dimensional component (L shaped bracket) was modelled using the residual stresses obtained for the flat plaques and the predictions were compared with the experimental warpage measurements. © 1996 The Institute of Materials.