Impact-induced delamination propagation on both tufted and untufted carbon fibre-reinforced plastics composite laminates was investigated. High-velocity impacts were performed on a ballistic gas gun. Initial and residual velocities were monitored with optical sensors especially developed for this study. Energy-absorption abilities were compared for different tufting parameters. The perforated specimens were inspected with an original technique allowing the observation of interlaminar delamination area for each interface. The existence of preferential propagation direction is highlighted. It is concluded that tufting helps to contain delamination and provides improved energy absorption depending on the tufting pitch.
This paper presents a comprehensive mechanical study of UHMWPE (Ultra High Molecular Weight Polyethylene) composite material under dynamic loadings. The aim of the study is to provide reliable experimental data for building and validate the composite material model under impact. Four types of characterization tests have been conducted: dynamic in-plane tension, out-of-plane compression, shear tests and plate impact tests. Then, several impacts of spherical projectiles have been performed. Regarding the numerical simulation, an intermediate scale multi-layered model (between meso and macro scale levels) is proposed. The material response is modelled with a 3d elastic orthotropic law coupled with fibre damage model. The modelling choice is governed by a balance between reliability and computing cost. Material dynamic response is unconventional [1, 2]: it shows large deformation before failure, very low shear modulus and peeling strength. Numerical simulation has been used both in the design and the analysis of tests. Many mechanical properties have been measured: elastic moduli, failure strength and EOS of the material. The numerical model is able to reproduce the main behaviours observed in the experiment. The study has highlighted the influence of temperature and fibre slipping in the impact response of the material.
This paper details the methodology developed to fit a material strength/failure model with mesh sensitivity, strain rate influence and triaxiality effect on plastic failure for a blast/ballistic configuration for a HSS plate. Data collection in different loading conditions in quasi-static and dynamic regimes has been done, following a given tests matrix based on the customer phenomenological analysis. A complete set of parameters has been find by numerically reproduce the tests and find the best compromise to fit all the tests performed with a unique set. Tests on large square clamped plates have been performed with three nose shapes (flat, hemispheric and conical) to validate the set of parameters. One case with perforation and another at failure initiation have been done for each geometry. Numerical works using the final set of parameters have shown very good agreement in the various impact conditions.
The perpetual evolution of soldiers light weight armors include now high technology ceramic, composite and polymeric in ballistic vest that are optimized by simulations. Knowledge of individual material response in the strain, strain rate regime closed to the threat stays mandatory and thus collecting parameters to fit material models guarantees reliable numerical investigations. Since 2015, THIOT INGENIERIE Shock Physics Laboratory has been selected by the French Defence procurement agency DGA-Land Systems to perform materials characterization in three main families of ballistic materials [1-2]. A coupled approach between laboratory experiments and numerical simulations has shown its relevance with ceramic and an Ultra High Molecular Weight PolyEthylene composite (UHMWPE). This paper presents succinctly the last part of those experimental investigations on a polymeric foam that is implemented on the soldier’s chest [3]. The material behavior under dynamic loading has been first evaluated using Split Hokinson Pressure Bars (SHPB) up to 5000s-1. Ballistic tests have been performed in a second time using Digital Image Correlation (DIC) with ultrahigh speed cameras at the back of the target plate to evaluate the damping behavior. Numerical simulations are under progress and the first results are promising.
Understanding concrete response facing warheads threats is important for both the design of strategic infrastructure protection and the prediction of warhead performances. This ongoing study aims at building a robust approach for the characterisation of concrete behaviour under ballistic impact of Kinetic Energy Penetrator (KEP). A set of tests has been developed and performed to fit the main parameters of the Holmquist Johnson Cook Concrete material model. Highly instrumented tests are conducted to improve the model prediction capability and to identify its limits. After a brief description of the test configuration, the paper focuses on the analysis of an impact test and presents preliminary simulation results.
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