Design of Braided Composites for Energy Absorption

ABSTRACT: This paper describes a model for simulating the crushing behavior and pre-dicting the energy absorption characteristics of triaxially braided composite tubes. The crushing model uses the finite element code ABAQUS along with a material module that describes the constitutive behavior of the braid material. The constitutive behavior includes the effects of damage accumulation, and scissoring and jamming of the braider tows. To fa-cilitate the model development, extensive material tests and tube crushing experiments were performed. Crushing tests were conducted on braided carbon fiber/epoxy-vinyl ester composite cir-cular tubes, which were supplied by USCAR’s Automotive Composites Consortium. All tests were conducted quasi-statically, and plug-type initiators were used to trigger the pro-gressive crushing. Experimental results show that the profile of the load-displacement curve and the overall energy absorption can be significantly affected by the fiber architec-ture and the fillet radius of the plug-type initiator being used. In order to verify the proposed model, simulation results for tubes with various braid an-gles, being crushed with different initiator plugs, are compared with the experimental data. Predictions from the proposed model correlate well with the test results, and provide useful information about the deformation of the tube and the failure mechanisms occurring as the tube is being crushed