Perforation of composite plates and sandwich panels under quasi-static punch and projectile loading

Analytical solutions for indentation, penetration and perforation of composite plates and sandwich panels subjected to quasi-static punch indentation and projectile impact were derived. The total deformation under the indenter or projectile was assumed to be the sum of local indentation and global panel deformation. The local indentation of a laminate was obtained by modeling the composite panel as a transversely isotropic half space, while the global deformation was obtained from plate theory. In the case of sandwich panels, local indentation is due to deformation of the incident facesheet and core crushing.; Discrete spring-mass models were used to calculate the impact response of the composite panels. Equivalent load resistance functions were obtained from the quasi-static analysis and adjusted for high strain rate. A generalized solution methodology for projectile impact of composite plates and sandwich panels was could then be proposed based on three key factors: (i) the contact load duration, (ii) the through-thickness transit time, and (iii) the lateral transit time. For load duration less than the through-thickness transit time, three-dimensional wave propagation governs the impact response. For load duration greater than the through-thickness transit time but less than the lateral transit time, the impact response consists primarily of two-dimensional propagating waves. Finally, the impact response can be predicted by a quasi-static model if the load duration is much greater than the lateral transit time.; The analytical models were used to determine the response and failure of E-glass/polyester plates, GLARE fiber-metal laminates and E-glass/epoxy-aluminum honeycomb sandwich panels under quasi-static indentation and projectile impact. Analytical solutions for the quasi-static force-deflection response were found to be within 12% of FEA results on E-glass/polyester panels and 10% of test data on an E-glass/epoxy-aluminum honeycomb sandwich panel. The two-dimensional wave propagation model was used to determine the ballistic limits of E-glass/polyester panels and GLARE fiber-metal laminates and predicted values were found to be within 20% and 13% of the experimental results, respectively. The quasi-static impact model was used to predict the ballistic limit for E-glass/epoxy-aluminum honeycomb sandwich impacted by hemispherical nose projectile and the predicted value was within 11% of test results.