Ballistic penetration of GRP composites: Identification of failure mechanisms and modeling

HungCheng Lu, Purdue University

Abstract

The response of woven glass fiber reinforced plastics (GRP) under ballistic penetration was investigated experimentally as well as numerically. The high strain rate ballistic penetration experiments were conducted with a 3-inch light gas gun at impact velocities of 180 m/s and 200 m/s. Four well defined failure modes were observed in the post-impact studies. A total Lagrangian explicit finite element formulation was presented to model the large deformation response of fiber reinforced composite material to impact and penetration. The inelastic response of each ply was described by an anisotropic rate dependent plasticity model. The interface between plies was treated separately through a contact/interface algorithm taking into account delamination, opening and subsequent closing of the interface and large sliding between plies. The parameters of the interface elements were selected in terms of the actual materials properties such as GIC. The parameters of the anisotropic plasticity model were determined experimentally by carrying out off-axis tension tests, off-axis compression tests, compression tests in the matrix direction and Arcan shear tests. The formulation was validated by carrying out analyses for these tests using the model parameters so obtained. The analyses results were found in good agreement with the test data within desired tolerance. A finite element model was used to simulate the ballistic penetration of composite plates at impact velocities of about 200 m/s. The velocity at the back surface of the composite plate, obtained numerically, was compared with the data measured experimentally using interferometry. It was found that the two reasonable agree within the assumptions made. In summary, an attempt was made to model the pre- and post-failure response of woven glass fiber reinforced composite targets under ballistic penetration.

Degree

Ph.D.

Advisors

Espinosa, Purdue University.

Subject Area

Aerospace materials|Plastics|Materials science

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