INVERSE MODELING OF INJECTION-MOLDING THERMAL-STRESSES TO OPTIMIZE TEMPERATURE AND PRESSURE HISTORY

The dimensional stability and mechanical and optical properties of inj ection molded articles are affected to a large extent by the distribut ion of residual stresses. The distribution of residual stresses varies as a result of the temperature and pressure history during the proces s. In this paper, two thermoelastic models were used to study the effe ct of processing conditions on generation of thermal stresses. Then, b ased these models, two inverse models were developed to calculate the unknown pressure history and initial melt temperature from a known res idual stress distribution in the final product. The models were succes sfully tested with stress data simulated by the forward models. The ef fect of experimental errors on the inverse methods was investigated by adding measured stress profiles were used to further test inverse mod els. The results are presented and discussed.