Shock loading response of sandwich panels with 3-D woven E-glass composite skins and stitched foam core

In the present study, periodical grids were selected to reinforce soft honeycomb cores of sandwich structures. The grid reinforced honeycomb core can be considered as a combined core with multi-level lattice configuration. In-plane compression tests were carried out to investigate the mechanical properties of carbon fiber sandwich with combined core. Experimental results indicated that the combined core sandwich specimens provided increased stiffness, specific stiffness, energy absorption and critical load, which were higher than the sum of honeycomb core sandwich specimens and grid core sandwich specimens. In addition, a Finite Element Method (FEM) model was proposed to calculate the critical buckling load of the combined core sandwich structures. The effects of core heights, honeycomb-wall thickness and face-sheet thickness on the critical buckling loads of the combined core sandwich structures were examined. The aforementioned experimental and numerical results indicated that the present sandwich structure with grid reinforced honeycomb core could provide improved structural properties for engineering structures.

On compressive properties of composite sandwich structures with grid reinforced honeycomb core

Low-velocity impact behaviour of a shear thickening fluid (STF) and STF-filled sandwich composite panels

Three-dimensional (3-D) spacer fabric composite is a newly developed sandwich structure, the reinforcement of which is integrally woven by advanced textile technique. Two facesheets of 3-D spacer fabric are connected by continuous fibers, named pile in the core, providing excellent properties like outstanding integrity, debonding resistance, light weight, good designability and so on. Usually the 3-D spacer fabric composite without extra reinforcement is a kind of core material. In comparison with the facesheet reinforced spacer fabric composite, here the composite without additional weaves is called mono-spacer fabric composite. In this paper, two kinds of mono-spacer fabric composites with integrated hollow cores have been developed, one with 8-shaped piles and the other with corrugated piles. The mechanical characteristics and the damage modes of these mono-spacer fabric composites under different load conditions have been investigated. Besides, effects of pile height, pile distribution density and pile structure on the composites mechanical performances were analyzed. It is shown that the mechanical performances of mono-spacer fabric composites can be widely adapted to the respective requirements through the choice of the structural factors.

Effect of Structure on the Mechanical Behaviors of Three-Dimensional Spacer Fabric Composites

Z-pinned laminates and sandwich materials are an important class of composites with current applications in aircraft and emerging uses in other light-weight engineered products. This paper reviews research advances in the manufacture, microstructural chacterisation, mechanical properties, environmental durability and other functional properties (e.g. electrical, thermal, damage sensing) of z-pinned composite materials and structures. The review reveals that z-pins can be used in create novel multifunctional laminates that uniquely combine a multitude of important properties including high interlaminar fracture and fatigue resistance, superior impact damage tolerance, increased thermal and electrical conductivities, damage sensing, and high-performance joining. Similarly, z-pins can impart sandwich composites with a novel combination of multifunctional properties that include high structural, damage tolerance, electrical and damage sensing properties. Research gaps in our understanding of z-pinned laminates and sandwich composites are identified. Future research opportunities to create next-generation z-pinned materials with even more versatile multifunctional properties are described.

Review of z-pinned laminates and sandwich composites

New fabrication technologies now allow for hybrid sandwich structures, known as X-core, to be manufactured. The X-core panels consist of a pin reinforced polymer foam core with carbon fiber face sheets. Carbon fiber or metallic (Titanium/Steel) pins are inserted into the foam core in the out-of-plane direction and extend from face sheet to face sheet. The through thickness three-point simply supported bending behavior of these panels is used to evaluate the collapse characteristics of the panels. Explicit experimental observations are used to calibrate analytical energy balance models describing the panel collapse as a function of geometry and properties. The mechanical response of X-core sandwich panels is compared to current sandwich materials for material selection.

M. C. Rice

Papers

Study on the Collapse of Pin-Reinforced Foam Sandwich Panel Cores