This paper applies a fatigue damage model recently developed for injection-molded long-fiber thermoplastics (LFTs) to predict the modulus reduction and fatigue lifetime of glass/polyamide 6,6 (PA6,6) specimens. The fatigue model uses a multiscale mechanistic approach to describe fatigue damage accumulation in these materials subjected to cyclic loading. Micromechanical modeling using a modified Eshelby-Mori-Tanaka approach combined with averaging techniques for fiber length and orientation distributions is performed to establish the stiffness reduction relation for the composite as a function of the microcrack volume fraction. Next, continuum damage mechanics and a thermodynamic formulation are used to derive the constitutive relations and the damage evolution law. The fatigue damage model has been implemented in the ABAQUS finite element code and has been applied to analyze fatigue of the studied glass/PA6,6 specimens. The predictions agree well with the experimental results.
Revised: April 13, 2011 |
Published: October 30, 2009
Citation
Nguyen B.N., V. Kunc, and S.K. Bapanapalli. 2009.Modeling Fatigue Damage in Long-Fiber Thermoplastics. In Proceedings of the American Society for Composites - Twenty-Fourth Technical Conference, with the Canadian Association for Composite Structures and Materials (Joint Canadian-American International Conference), September 10-13, 2009, Wilmington, DE, edited by JW Gillespie, Jr. and SV Hoa. Lancaster, Pennsylvania:DEStech Publications.PNNL-SA-66695.