The influence of preload and boundary conditions on pre-damaged composite plates subject to soft-body impact

•We investigate the influence of soft-body impacts onto pre-damaged CFRP plates.•Material delamination is simulated using a bilinear cohesive element failure model.•Simulation results are validated with comparison to theory and test data.•Tensile preload and plate compliance reduce the extent of impact damage.

This research investigates the influence of preload and boundary condition compliance on low-velocity impact damaged CFRP T800S/3900-2B plates subject to secondary higher-velocity soft-body impact (50 J, 75 J, 100 J). A bilinear cohesive element based delamination model combined with ply-based composite material failure was developed using LS-DYNA 971. Double Cantilever Beam (DCB), 3-point End-Notched Flexure (ENF), and Fixed Ratio Mixed Mode Bending (FRMMB) simulations validate the accuracy of the delamination model when compared with theory. The low-velocity impact simulations were shown to compare well with the results of drop-tower impact experiments and ultrasonic inspection data in terms of maximum impact force and projected delamination area. An investigation of boundary condition compliance in the direction of impact showed a reduction in peak impact force, interlaminar delamination and intralaminar failure with increasing coupon translation. High-velocity impact simulations based on the model with initial damage showed a reduction in interlaminar delamination damage with tensile preload when compared to compressive preload and unloaded cases for all impact energies.

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