The present paper investigates the impact performance of woven-fabric carbon-fibre composites based upon both thermoplastic-and thermoset-matrix polymers under highvelocity impact loading by conducting gas-gun experiments at impact velocities of up to 100 m.s −1. The carbon-fibre reinforced-polymers (CFRPs) are impacted using soft-(i.e. gelatine) and hard-(i.e. aluminium-alloy) projectiles to simulate either a soft bird-strike or a hard foreign-body impact (e.g. runway debris), respectively, on typical composites employed in civil aircraft. The out-of-plane displacements of the impacted composite specimen are obtained by means of a three-dimensional Digital Image Correlation (DIC) system for the soft-projectile impact on the composites and the extent of damage is assessed both visually and by using portable C-scan equipment. The perforation resistance and energy absorbing capability of the composites are also studied by performing high-velocity impact experiments using the hard-projectile and the resulting extent and type of damage are identified. In addition, a Finite Element (FE) model is also developed to investigate the interaction between the projectile and the composite target.
This research presents a detailed experimental and numerical study on the compressive failure of woven fabric reinforced thermoplastic composites, with an open-hole and with a pinned open-hole. The experimental evaluations are performed on the composite specimens using the Combined Loading Compression (CLC) evaluation method. Experimental results, including load response and damage morphology, are obtained and analysed. A meso-scale damage model is developed, based on Continuum-Damage-Mechanics (CDM), for predicting damage in woven fabric reinforced composites. The developed model, which can capture fibre fracture and matrix cracking, as well as the nonlinear response within the woven composite materials, is employed to conduct virtual Combined Loading Compression (CLC) tests. Numerical simulation results are compared with the extracted experimental results for model validation. Good correlation is achieved between experimental and computational results for both the open-hole and the pinned open-hole, with a twostage failure process being observed for the pinned open-hole.
The interaction of a screw dislocation with a circular inhomogeneity near the free surface is discussed in this paper. By using the complex potential and conformal mapping technique, an explicit series solution is obtained. Then, the solution is cast into a new expression to separate the interaction effects between the dislocation, inhomogeneity, and free surface. The new expression is not only convenient to reveal the coupling interaction effects, but also helpful to improve the convergence of the solution. As an application of the new expression, a simple approximate formula is presented with high accuracy. Finally, the full-field interaction energy and image force are evaluated and studied graphically. It is found that when the screw dislocation, inhomogeneity, and free surface are close to each other, their interaction effects strongly and intricately couple in the near field. In the case of a soft inhomogeneity or a hole, there is an unstable equilibrium point of the screw dislocation between the inhomogeneity and free surface, whereas in the case of a hard or rigid inhomogeneity, there is an unstable equilibrium point on the opposite side of the inhomogeneity.
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