ORALS

Tsai et al [1] employed a plate impact test configuration to study shock wave propagation in a S-2 glass fiber reinforced – polyester matrix composite (GRP). Hugoniot Elastic Limit (HEL), Hugoniot and Precursor Decays were determined from plate impact data using thin (~6.8 mm) and thick (~13.6 mm) GRP targets. The HEL like points in the VISAR (“free surface velocity profiles”) data were significantly influenced by the impact velocity or shock stress levels. The interpretations of experimentally observed HEL and nonlinearity in the data for two different GRP thicknesses at a range of impact velocities remained speculative and inconclusive. To provide some insight into the effect of deformation and matrix microcracking on the VISAR profiles (or particle velocity history), computer simulations of both thin and thick plate impact experiments were performed using the ABAQUS finite element code [2]. Fraser [3] implemented a constitutive model [4] that is based on a Helmholtz Free Energy function and continuum damage mechanics. Fraser performed computational modeling of the thin (6.8 mm) plate impact tests and determined the parameters for strain-based damage initiation and propagation models. The damage modes were: matrix shear cracking, volume expansion under compressive loading, delamination, and fiber breaking in tension and shear. The respective model constants were calibrated through comparisons between the VISAR data and computed free surface velocity profiles. Based on the simulation results, it is suggested that the HEL point is due to elastic-elastic cracking (EEC) of the matrix materials under compressive loading. In simulations, the damage (microcracking of the matrix) emanates from the impact plane and progressively damage the GRP target plate in the plate impact experiments. Recently, Rahim [5] has performed ABAQUS simulations of shock wave propagation in thick (~ 13.6 mm) GRP using the calibrated model constants for the thin targets in order to verify and validate the generality of the constants in predicting damage evolution as the wave travels further away from the impact plane.

References:
[1] Liren Tsai, Fuping Yuan, Vikas Prakash, and Dattatraya P. Dandekar, “Shock compression behavior of a S2-glass fiber reinforced polymer composite,” Journal of Applied Physics, 105 (2009) 093526. [2] Abaqus/Explicit, a special-purpose Finite-Element analyzer that employs explicit integration scheme to solve highly nonlinear systems with many complex contacts under transient loads. https://www.3ds.com/products-services/simulia/products/abaqus/ [3] James Fraser, “ABAQUS implementation of a hyperelastic damage model for glass-reinforced polymers under shock and impact loading,” A Thesis presented in partial fulfillment of requirements for the degree of Master of Science in the Department of Mechanical Engineering, The University of Mississippi, May 2022. [4] M. I. Barham, M. King, J. , G. Mseis, and D. R. Faux, “Hyperelastic Fiber-Reinforced Composite Model With Damage, Technical report LLNL-MI-644243,” (2013). [5] Othman Hama Rahim, Unpublished results, University of Mississippi, Oxford, MS, USA.