Executive Summary : | The design of robust, lightweight, protective structures against blast loading is a primary area of research focus in defence, aerospace, marine industries, and nuclear power plants. The monolithic metal or ceramic sheets that are generally used for such applications have very low strength-to-weight ratios. Sandwich structures with a high energy-absorbing core offer high strength-to-weight ratios and improve energy absorption capacity for protection against shock loads. The auxetic metamaterials, which possess a counterintuitive behaviour, have a negative Poisson’s ratio and have been proven to have better energy absorption capacity than conventional honeycomb cores. The recent research efforts on developing newer auxetic metastructures using topology optimization and machine learning approaches have paved the way for developing a new class of sandwich structures with tunable material properties. Most of the pertinent investigations on static/dynamic behaviour of sandwich structures with auxetic core have employed the auxetic materials possessing auxeticity in either tension or compression. The influence of dual mechanism cores having tunable thermal expansion coefficients and Poisson’s ratios on the mechanical behaviour of sandwich structures is not yet fully understood. Furthermore, the influence of nonlinear temperature distribution and arbitrary geometrical shapes was also not thoroughly investigated in the studies available in the literature. The recent advancements in computer technology have reduced the computational time for FE simulations. However, the meshing of complicated domains is a time-consuming process, and there is a need to reduce bottlenecks in the process of modelling-to-meshing-to-solution. The isogeometric approach involves the use of non-unform rational B-Splines (NURBS) for the approximation of both geometrical and solution variables, thereby offering a strong integration between modelling and analysis. The present work proposes to employ an isogeometric approach for investigating the influence of core auxeticity on sandwich structures' behaviour against blast loading conditions. A comparative analysis of the performance of sandwich structures with honeycomb cores and different types of auxetic cores will be done to better understand the influence of core configuration on the blast performance of protective structures. The thermomechanical postbuckling behaviour of sandwich plates and shell panels with auxetic cores will also be compared for different types of cores with tunable Poisson’s ratio and thermal expansion coefficients. The proposed work will result in benchmark solutions for the design of protective sandwich structures. The in-house code to be developed for the proposed work will also contribute to developing an indigenous platform for the design of sandwich structures. |