A novel approach to estimation of residual strength of laminated polymer composites under compression after impact

Abstract

This work is dedicated to the experimental study of the influence of preliminary dynamic loading on the residual strength of the laminated polymer composite under compression. A series of low-velocity transverse drop-weight impact tests in a wide range of energies was carried out, followed by quasi-static compression of composite specimens with two reinforcement schemes [0/90]n and [±45]n. Nonlinearity of the obtained dependences of residual static strength on the energy of preliminary dynamic loading has been discovered. It has been noted that there are three characteristic stages on the diagram of fiberglass laminate’s impact sensitivity: area of impact insensitivity; area of reduced bearing capacity; area of achieving the minimum bearing capacity. The identified patterns are consistent with the data on the response of specimens during impact, as well as with specimens’ surface damage after dynamic loading. An anisotropy of the composite's impact sensitivity has been discovered. A novel approach to estimation of residual strength of laminated polymer composites under compression after impact and determination of impact sensitivity thresholds based on the use of mathematical models has been proposed. A new model of residual strength has been developed and tested, its applicability for description of the mechanical behavior of composites with various reinforcement schemes has been demonstrated