Compressive behavior of pultruded composite plates with circular holes

Compressive behavior of E-glass fiber/isophthalic polyester resin matrix pultruded composite sheet material is reported for two thicknesses. The effect of circular holes on compressive strength and failure strain was also investigated. In the first series of tests, compression tests were performed with plate specimens without any hole. These specimens were instrumented with several pairs of back-to-back axial strain gages at different locations on the surface of the specimen to capture global buckling (if any) during compression. In the second series of tests, plate specimens with circular holes were prepared. A wide range of diameter to width ratio of D/W=0.075–0.75 was chosen. The open-hole specimens were also instrumented with several strain gages (combination of single and strip gages) in and around the surface of the hole to determine the strain distribution, strain concentration factor, transverse and through-the-thickness normal strain, etc. A relationship between the compressive strength and hole-diameter was established, and compared with the base line material properties. Finally, an attempt was made to determine the compressive failure initiation mechanisms and failure progression mechanisms in the presence of holes through sectioning and examining under a stereo microscope.