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Anisotropic Material Damage Model of Randomly Oriented Thermoplastic Composites for Crash Simulation
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
In this research, a material model was developed with orthotropic properties for in-plane damage to support finite element strength analysis of components manufactured from a randomly oriented long-fiber thermoplastic composite. This is a composite material with randomly oriented bundles of carbon fibers that are approximately one inch in length. A macroscopic characteristic of the material is isotropic in in-plane terms, but there are differences in the tension and compression damage characteristics.In consideration of these characteristics, a material model was developed in which the damage progression rate is correlated with thermodynamic force and stress triaxiality. In-plane damage was assumed to be isotropic with respect to the elements. In order to validate this material model, the results from simulation and three-point bending tests of closed-hat-section beams were compared and found to correlate closely.However, in the case of axial compression of a hat-section beam, it was found that although the initial peak load corresponded closely, the peak loads after the second one did not match.As a cause for this, it is conceivable that the damage applied in the transverse direction is different from that of the axial compression direction. A test that would identify the relationship between these differing instances of damage was devised, and the damage characteristics were measured. It was found from the results of this test that the in-plane damage progression would need to be given orthotropic properties.The orthotropic damage characteristics were additionally implemented in the material model and the axial compression of the hat-section beam was calculated. It was confirmed that the loads increased from the second load peak and on. This suggests that the conceptual approach of the material model is correct.