A multiple particle impact model for prediction of erosion in carbon-fiber reinforced composites

Material loss and degradation due to erosion remains a major concern in engineering applications for composite materials. A finite element based model has been developed to predict the erosion behavior of unidirectional carbon fiber-epoxy (CFRP) composites subjected to solid particle impacts. In this model, the CFRP plate is subjected to multiple particle impacts at a velocity of 45 m/s, with steel balls as the erodent particles. The Influence of impact angle, erodent particle stream orientation (parallel and transverse to the fiber direction) and erodent particle size has been studied by varying the impact angle from 15 degrees-90 degrees and particle sizes considered are of radii 150 mu m, 200 mu m and 250 mu m. The model captures the influence of the erodent particle to particle impacts and the target surface properties by defining two new ratios, kinetic energy ratio, "eta(k)" and substrate surface property ratio, "eta(s)". The cumulative eroded mass predictions are higher for transverse to fiber impact as compared to parallel to fiber impacts. It is also observed that as the erodent size increases the total eroded mass loss increases at all impact angles. The eroded mass predictions obtained from the numerical model compare favorably with the eroded mass results obtained from experimental data reported in the literature

Stress Wave Attenuation in Aluminum Alloy and Mild Steel Specimens Under SHPB Tensile Testing

Investigations on the effect of intensity of incident pressure wave applied through the striker bar on the specimen force histories and stress wave attenuation during split Hopkinson pressure bar (SHPB) tensile testing are presented. Details of the tensile SHPB along with Lagrangian x-t diagram of the setup are included. Studies were carried out on aluminum alloy 7075 T651 and IS 2062 mild steel. While testing specimens using the tensile SHPB setup, it was observed that the force calculated from the transmitter bar strain gauge was smaller than the force obtained from the incident bar strain gauge. This mismatch between the forces in the incident bar and the transmitter bar is explained on the basis of stress wave attenuation in the specimens. A methodology to obtain force histories using the strain gauges on the specimen during SHPB tensile testing is also presented. Further, scanning electron microscope images and photomicrographs are given. Correlation between the microstructure and mechanical properties is explained. Further, uncertainty analysis was conducted to ascertain the accuracy of the results

The Representation of Fiber Misalignment Distributions in Numerical Modeling of Compressive Failure of Fiber Reinforced Polymers

International audienc

The compressive behaviour of composites including fiber kinking: modelling across the scales

International audienc