An experimental study of damage accumulation in balanced CFRP laminates due to repeated impact

The behaviour of balanced laminates (symmetric, antisymmetric and asymmetric) under repeated low energy hits of a 12.1 mm hemispheric impactor was evaluated. The resistance to the impulsive force was found to be influenced by the stacking sequence and the crack path through the laminate. The symmetric plate with different ply directions proved to have best resistance to impact. The rate of damage progression in the event was characterised by an equation from the energy profile that correlates the propagation energy and time. This was differentiated to give the rate of damage evolution. A comparison of the bending stiffness obtained from the force-displacement plot of the first impact, revealed that the symmetric composite had the highest stiffness. Noted at perforation were fibre breakage and matrix cracking

Impact characterisation of doubly curved composite structure

Under repeated impact composite domes subjected 6 J energy, changes locally with increasing drop height. The action of the dynamic load generates reactions at the support and bending moments at points on the surface of the composite. The peak loads were noted to increase and stabilise about some mean value; and the 150mm diameter shell was more damage tolerant compared to the 200 mm diameter one

A study of repeated impact loading on a symmetrical carbon fibre laminate

The behaviour of a symmetric laminate under repeated low energy hits of a 12.1mm hemispheric impactor was evaluated. The laminate was able to endure 20 collisions with the striker before perforation. The rate of damage progression was characterised by an equation from the energy profile that correlates the propagation energy and time. The function was represented by a sixth order polynomial. This was differentiated to give the rate of damage evolution. The contact time related to theimpact events with the same degree of polynomial. At perforation fibre breakage and matrix cracking were observed

Energy absorption and bending stiffness in CFRP laminates : the effect of 45º plies

The impact characteristics of cross-ply and angle-ply composite laminates were investigated, with an instrumented impact drop tester by performing gravity assisted drop tests on [0/90]6s and [0/45/90]4s laminates. The impact energy was kept constant at 12 J for all the tests. From the dynamic responses presented here as force history, energy history and force-displacement plots, relevant characteristics such as contact time, delamination load, absorbed energy, bending stiffness, after impact deflection etc were obtained. The plots were non-smooth, disclosing the salient features of the composites. It was important to note that the [0/45/90]4s was more resistant to impact bending, but incurred more damage as exhibited by its higher contact time and absorbed energy. The laminates were sectioned through the impact point and magnified macro and micro photographs were taken to show the failure modes, which include delamination, matrix cracking etc

Damage threshold and the impact characteristics of +/- 45° and +/- 60° CFRP laminates - Poster Presentation

Poster presentation investigating damage thresholds and the impact characteristics of CFRP laminates

An experimental study of the response of composite pipes under impact loading

This paper discusses an experimental study of the response of composite pipes under impact loading. It was presented at the 2007 International offshore and polar engineering conference held in Lisbon