A Study on Creep Analysis of Automobile Instrumental Panel

The operating temperature of IP (Instrument panel) of passenger vehicles usually ranges from under freezing temperature to over glass transition temperature. The varying temperature induces thermal expansion of IP. Coupled with constraint condition, thermal expansion causes thermal deformation, which sometimes turns into unwanted permanent deformation. In this study, non-linear finite element method has been introduced to study the deformation behavior of IP in thermal cycle test. The time-dependent deformation behavior of IP has been investigated using creep material model. To quantify the creep behavior of polymer material which has been applied to IP, flexural creep test has been performed on various stress, temperature condition. The test result has been fitted into a time-hardening type creep constitutive equation. The coefficient of creep equation has been validated with the comparison of test result and FEM simulation result. In view of short-term thermal loading case, such as thermal cycle test, the effect of creep has been studied by comparison with results of elastic plastic analysis and thermal cycle test result. With this study, the quality degradation of IP with operating time can be predicted