Blast resistance and energy mitigation behavior of sandwich composite materials
An analytical and experimental study on the blast performance and energy mitigation behavior of sandwich composites has been conducted in this dissertation. The findings from the present study are summarized below. (1) The energy components of a gas have been defined and expressed with the physical parameters of the gas, such as pressure, density, local sound velocity, and particle velocity. An analytical method was developed using the jump conditions of the shock wave front and the Rankine-Hugoniot relations of gases to evaluate these parameters, and consequently evaluate various energies. (2) Based on the energy evaluation, a new one-dimensional fluid/structure interaction model, which considered the compressibility of a gas, was developed and implemented. The one-dimensional gas-dynamic theory (Rankine-Hugoniot relation) was utilized to consider the compressibility of the gas. The comparison between the experimental results and the analytical prediction shows that the proposed model can give a more accurate prediction than the previous models (Taylor, 1941; Xue and Hutchinson, 2004; Fleck and Deshpande, 2004; Deshpande and Fleck, 2005; Kambouchev, et al, 2006, 2007). (3) The deformations in the core of a sandwich composite have been visualized using Digital Image Correlation (DIC) techniques. The fluid/structure interaction behaviors of sandwich composite were evident from the time history of the transverse strain through the thickness and the deflection contour on the back face. Moreover, the transverse strain through the thickness shows a highly non-linear profile. (4) It helps to improve the blast resistance of the sandwich composites using a core with monotonically increased wave impedances and placing the layer with lowest wave impedance face the blast loading. This configuration gives rise to stepwise compression in the core and consequently maintains structural integrity. (5) Two specific fixtures were designed to implement the static uni-axial and bi-axial in-plane compressive loadings on the sandwich composites prior to being subjected to a transverse blast loading. The results show that the in-plane compressive loading causes local buckling in the front face sheet and delamination in the back face sheet of the sandwich composites. These mechanisms highly reduce the blast resistance of the sandwich composites.
Naval engineering|Aerospace engineering|Mechanical engineering
"Blast resistance and energy mitigation behavior of sandwich composite materials"
Dissertations and Master's Theses (Campus Access).