PIN-LOADED CHARACTERISTICS OF ORTHOGONAL 3-D CARBON-EPOXY COMPOSITE-MATERIALS

Results are presented from an experimental program which measured the pin-loaded strength of orthogonal 3-D composites. Single hole pin-load ed specimens were tested in a variety of weave structures in 3-D carbo n preforms infiltrated with the resin system, CIBA-GEIGY Gy260. For si ngle-hole pin-loaded joints, the various modes of failure have been is olated and the corresponding strengths measured. The influence on the pin-bearing strength of several important parameters such as weave str uctures, yarn spacing, the amount of carbon filaments in the in-plane direction, and in the through-the-thickness direction, the ratio of wi dth to hole diameter and edge distance are discussed in light of the r esults. The effects of in-plane fibers and out-of-plane fibers on pin- loaded strength in orthogonal 3-D composites are also discussed. The b ehavior of a single hole pin-loaded specimen is discussed relative to strength, load-displacement behavior and failure modes. Based on the e xperimental observations, some guidelines are given to help in the sel ection of the optimum weave structure and geometric parameters for pin -loaded orthogonal 3-D composites.