DYNAMIC RESPONSE OF STRUCTURAL MATERIALS TO SHOCK LOADING

Abstract

An analytical and experimental study has been conducted to investigate the blast resistance and mitigation behaviors of structural materials. Understanding the failure mechanisms in these materials will lead to an optimal design of light weight structures capable of withstanding blast loadings. This improved blast mitigation property is extremely important in protecting many commercial, naval, aerospace and defense structures. A controlled study has been performed to understand fracture and damage in glass panels subjected to air blast. A shock tube apparatus has been utilized to obtain the controlled blast loading. Five different panels, namely plain glass, sandwiched glass, wired glass, tempered glass and sandwiched glass with film on both the faces are used in the experiments. Fully clamped boundary conditions are applied to replicate the actual loading conditions in windows. Real-time measurements of the pressure pulses affecting the panels are recorded. A post-mortem study of the specimens was also performed to evaluate the effectiveness of the materials to withstand these shock loads. The real time full-field in-plane strain and out-of-plane deformation data on the back face of the glass panel is obtained using 3D Digital Image Correlation (DIC) technique. The experimental results show that the sandwich glass with two layers of glass joined with a Polyvinyl butyral (PVB) interlayer and protective film on both the front and back face maintains structural integrity and out performs the .other four types of glass tested. Experimental and numerical studies were conducted to understand the effect of plate curvature on blast response of aluminum panels. A shock tube apparatus was utilized to impart controlled shock loading to aluminum 2024-T3 panels having three different radii of curvatures: infinity (panel A), 304.8 mm (panel B), and 111.76 mm (panel C). Panels with dimensions of 203.2 mm x 203.2 mm x 2 mm were held with , mixed boundary conditions before applying the shock loading. A 3D Digital Image Correlation (DIC) technique coupled with high speed photography was used to obtain out-of-plane deflection and velocity, as well as in-plane strain on the back face of the panels. Macroscopic postmortem analysis was performed to compare the yielding and plastic deformation in the three panels. The results showed that panel C had the least plastic deformation and yielding as compared to the other panels. A dynamic computational simulation that incorporates the fluid-structure interaction was also conducted to evaluate the panel response. The computational study utilized the Dynamic System Mechanics Analysis