This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Material Characterization for Predicting Impact Performance of Plastic Parts
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 28, 1999 by SAE International in United States
Annotation ability available
Finite Element Codes are useful tools for predicting the structural performance of plastic components. Through the use of these tools conceptual designs can be assessed and mature designs can be optimized; thereby, shortening the costly build and test cycle. In the past predictions were most useful in predicting the load-displacement response of the component. This could be accurately done by accurately modeling the geometry and boundary conditions and by knowing the modulus of the material. As plastics have increasingly been used in more demanding applications such as load bearing automotive components, other nonlinear deformation processes and failure mechanisms become important. In plastics the yield stress is typically very strain rate sensitive and can also be pressure dependent as well. To accurately predict impact performance it is important to characterize the rate and sometimes the pressure dependence of the material and to incorporate this into the finite element material model. An even more important consideration is the actual failure event. Will the material behave ductiley or brittlely? Under what conditions will it behave ductilely or brittlely? In order to answer these questions, the strain rate, temperature and stress triaxiality of the applications needs to be known as well as the affect of these parameters upon the material performance. Once the expected failure mode is ascertained, the next step is to determine the actual failure criteria of the material. Determining the failure criteria of the material is more involved; however, it is critical for determining whether the part can meet the impact requirements of the application. This paper will outline a material characterization approach for establishing material deformations models, anticipated failure modes, and ductile and brittle failure criteria.
CitationWoods, J. and Trantina, G., "Material Characterization for Predicting Impact Performance of Plastic Parts," SAE Technical Paper 1999-01-3178, 1999, https://doi.org/10.4271/1999-01-3178.
- Stokes V.K. Nied H.F. “Solid Phase Sheet Forming of Thermoplastics - Part I: Mechanical Behavior of Thermoplastics to Yield,” ASME Journal of Engineering Materials and Technology 108 107 1986
- Stokes V.K. Nied H.F. “Solid Phase Sheet Forming of Thermoplastics - Part II: Mechanical Behavior of Thermoplastics After Yield,” ASME Journal of Engineering Materials and Technology 108 113 1986
- Nimmer R. P. Woods J. T. “An Investigation of Brittle Failure in Ductile, Notch-Sensitive Thermoplastics,” Polymer Engineering and Science 32 16 1126 1137 1992
- Woods J. T. deLorenzi H. G. “An Assessment of Crazing Criteria for Polyetherimide in 3-Dimensional Stress Space,” Polymer Engineering and Science 33 21 1431 1437 1993
- deLorenzi H. G. Woods J. T. “Strain Rate and Temperature Effects on the Failure of Notched Polycarbonate and Polyetherimide Beams,” Proceedings of the 1993 Society of Plastics Engineers (SPE) Annual Technical Meeting SPE Brookfield, CT 1411 1417 1993
- Woods J. T. Nimmer R. P. Ryan K. F. “The Development and Validation of Rate Dependent Brittle Failure Criterion for Polycarbonate and Polyetherimide,” Proceedings of the 1994 Society of Plastics Engineers (SPE‚ Annual Technical Meeting SPE Brookfield, CT 1995