Characterization and Modeling of TPO Polymer Systems for Interior Energy Management Applications

摘要

The increasing use of TPO materials in automotive energy management applications calls for better understanding of how to represent those materials in computational environments. Tools such as finite element analysis can provide good insight into deformation modes and areas of maximum stress and strain in an impact event, but cannot robustly predict actual force or deflection magnitudes or material failure for TPO's. Any material model used in a finite element analysis should first be correlated to a physical impact test which isolates the contribution of the material model only. This allows the engineer to then determine the level of confidence which is associated with use of that material model. Initial temperature has the single biggest effect on performance of TPO materials, followed by plastic strain rate Both factors are critical in predicting the performance of TPO materials, however, currently available constitutive models do not fully represent all key material responses in a single model Development of a viscoelastic-viscoplastic material model tailored for TPO's is required to better represent this class of materials. There are several choices of test method for generation of material data inputs. The most common is tensile testing due to ease of the test, established international standards for low-rate testing, and reducing the data into characteristic values. Compression testing provides the ability to complete a truly constant strain rate test, but requires additional complexities when testing, particularly at high strain rates. Automotive interior applications are well represented by data sets that cover plastic strain rate ranges up to 300/s While some specific applications or designs may contain higher strain rates, the general population of interior energy management applications will be covered by this range.