Fluid-structure interaction of metallic and composite plates subjected to dynamic loading

An important consideration when designing structures from composite materials is theirsusceptibility to impact damage. Even under relatively low velocity impact, compositesare vulnerable to internal damage caused by transverse loads, but unlike metallicstructures, material damage can be hidden within the material and show no form ofexternal damage. In some cases, barely visible impact damage (BVID) may occur, whicheven if detected by visual inspection would give no true indication to the severity of theinternal material degradation. Since many composites are being utilised in highperformance applications, it is important that the response of composites under impactloading is fully understood.This research examines the transient dynamic response of metallic and composite platessubjected to low velocity impact loading for conditions in both air and underwater byconducting a series of experiments and non-linear numerical analysis using the finiteelement technique. To verify the accuracy of this method for investigating impactproblems, several numerical validation studies have been conducted using publishedresults.An instrumented low velocity impact rig was used to acquire experimental data forimpacts in air and underwater for both aluminium and composite plates. Experimental results were compared with numerical and theoretical solutions and found to be in goodagreement.For underwater impact, the numerical modelling incorporated the use of ArbitraryLagrange Euler (ALE) methodology, therefore, analysing the problem with coupled fluidstructureinteraction. The effect of the water surrounding the target plates was found toreduce the peak accelerations and also reduce the overall impact duration. X-Rayimagery of the composite plates also showed visibly reduced damage for the submergedtest specimens.This research provides data on the impact response of metallic and composite materials,and validates numerical methodologies for use in future work on fluid-structureinteractions which show strong potential for relevant industrial applications