Experimental Damage Evaluation of Honeycomb Sandwich with Composite Face Sheets under Impact Load

Abstract

Aerospace structures are highly vulnerable to impact loads whose damage tolerance, and its resistance vary over the range of impact velocity. Honeycomb sandwich structures are used in aerospace industries where mass efficient and impact resistant structures are needed. However, the structural integrity of these structures is reduced by impact load due to tool drop, runway debris, hailstones and improper handling of the structure. A thorough investigation of the damage behaviour of honeycomb sandwich under lowvelocity impact and the post-impact residual strength determination is required to design a crashworthy lightweight structure. This paper presents the experimental evaluation of specific energy absorption using Charpy impact, residual compressive strength by compression after impact and damage evaluation of honeycomb sandwich structures having composite face sheets. Parametric studies on composites and honeycombs are carried out by varying the cell size, cell thickness, core height, impact velocity, thickness and orientation of lamina. Densely packed thick honeycombs provide higher fracture energy. Under transverse compressive loading, the honeycomb core undergoes cell wall buckling, crushing and densification. Load-displacement history under in-plane compression and compression after impact for different impact energies is observed. The present study contributes for the understanding how various parameters affect the characteristics of face sheet indentation and plastic buckling of honeycomb sandwich structures with composite face sheets, thereby providing useful guidelines for its potential applications in impact engineering.

Effects of Deceleration on Secondary Collisions between Adult Occupants and the Vehicle in Frontal Crash Accidents

“…In some countries, reduction in fatalities from road traffic crashes has been treated as one of public policy objectives. Many researches have been conducted and many measures have been taken to tackle the problems [1][2][3]. As a kind of protection device widely used in the field of passive safety of vehicles, seat belts are of great importance in securing safety and saving lives in frontal crash accidents by restraining the occupants and preventing secondary collisions between drivers or passengers and the vehicle [4].…”