Damage in Armor Ceramics Subjected to High-Strain-Rate Dynamic Loadings: The Edge-On Impact Test
Résumé
The objective of this chapter devoted to "Damage in armor ceramics subjected to high-strain-rate dynamic loadings" is dedicated to the Edge-On-Impact testing technique. This experimental method is commonly used to investigate the high strain-rate tensile damage induced in armor ceramics when subjected to impact loading. The principle of EOI test is the following: a metallic cylindrical projectile hits the edge of a rectangular tile which thickness is generally smaller than the projectile diameter. The compressive strength of ceramics being much higher than their tensile strength, tensile damage occurs without inducing any compressive damage near the impact point. This anisotropic damage, called multiplefragmentation process, is composed of a large number of oriented cracks. Two testing configurations are generally considered. In the so-called open configuration an ultra-high-speed camera is used to visualize the fragmentation process as function of time. In the sarcophagus configuration, a metallic or polymeric casing is used to keep the fragments in place so the damage pattern can be analyzed further by microscopy or X-ray micro-tomography analysis. Next the damage pattern can be compared to numerical predictions. In this chapter, a short review of experimental works proposed in the literature based on the use of EOI tests is presented. A numerical study is introduced to assess the loading history and loading-rate involved in such test. Next, experimental results conducted with 4 silicon carbide ceramics are presented. Finally, these experiments are numerically simulated in a FE code with the DFH (Denoual-Forquin-Hild) anisotropic damage model and the final damage patterns are compared to post-mortem observation in terms of cracking density. Last, the strengths, weaknesses and drawbacks of EOI tests are discussed.
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