Sandwich-structured composite

About: Sandwich-structured composite is a research topic. Over the lifetime, 5853 publications have been published within this topic receiving 101126 citations.

Ballistic Resistance of 2D and 3D Woven Sandwich Composites

Abstract: In the present study, ballistic resistance of sandwich composite structures for vehicle armor panel applications was investigated. The core material of the sandwich structure was a layer of Alumina ceramic and a layer of composite backing, sandwiched between 2D plain weave composite skins. The ballistic performance of sandwich materials with 3D backing was compared to the baseline 2D plain weave backed composites. An IMACON 200 high-speed camera was used to obtain high-speed photographs of the ballistic events of penetration and damage. These images were analyzed to study real time damage mechanism of the strike face surface of several targets and subsequently to obtain average resistive force of target points during impact. Velocities of projectile (armor piercing bullets) were recorded in all the experiments and were found to be in the range of 915 – 975 m/s. Post mortem analyses, which included sectioning of panel, were performed. Results showed that armor panels with 3D woven backing had a higher ballistic efficiency than the 2D baseline panels, strike face damage mechanics were predominantly axi-symmetric about the impact point and panels with 3D backing had controlled delamination and fewer complete penetrations.

Impact response of aluminum foam core sandwich structures

Abstract: Sandwich panels, comprised of metallic foam core and face sheets, are widely used to withstand impact and blast loadings. Based on the actual application requirements, the performance can be optimized with the proper combination of face sheets design. In this paper the impact responses of aluminum foams with various tailored face sheets, whose behavior represents elastic, elastic-ideally plastic and elastic–plastic strain work hardening, were investigated experimentally. The experiment was carried out using hemispherical indenters on blocks of aluminum foam with and without the face sheet. Competing failure modes for the initiation of failure are discussed based on comparison of energy absorption capacity. Results show that increase in thickness of foam and the use of face sheet enhances the impact energy absorption capacity. The type of face sheet not only affects the energy absorption capacity but also the failure mode for the foam blocks. Aluminum foam blocks with stainless steel sheet are strong enough to withstand the pre-designated impact loading without penetration damage. At the same time, this study also provides a comparison of the impact performance, in terms of impact energy and failure mode, among blocks with different face sheets under the low velocity impact.

A multi-scale approach for the simultaneous shape and material optimisation of sandwich panels with cellular core

Abstract: This work deals with the problem of the optimum design of a sandwich panel made of carbon-epoxy skins and a metallic cellular core. The proposed design strategy is a multi-scale numerical optimisation procedure that does not make use of any simplifying hypothesis to obtain a true global optimum configuration of the system. To face the design of the sandwich structure at both meso and macro scales, a two-level optimisation strategy is employed: at the first level the goal is the determination of the optimum shape of the unit cell of the core (meso-scale) together with the material and geometric parameters of the laminated skins (macro-scale), while at the second level the objective is the design of the skins stacking sequence (skin meso-scale) meeting the geometrical and material parameters provided by the first-level problem. The two-level strategy is founded on the polar formalism for the description of the anisotropic behaviour of the laminates, on the NURBS basis functions for representing the shape of the unit cell and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, the multi-scale strategy is applied to the least-weight design of a sandwich plate subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell, on the global buckling load of the panel and geometrical as well as manufacturability constraints related to the fabrication process of the cellular core.