Effects of Hole-size and Environment on the Mechanical Behaviour of a Quasi-isotropic AS4/3501-6 Laminate in Tension, Compression and Bending; Technical rept

摘要

This report describes the results of open-hole-tension (OHT), open- hole-compression (OHC) and open-hole-four-point-bend (OHB) tests conducted on AS4/3501-6 quasi-isotropic (45/0/- 45/90)2s laminates in the room temperature dry (RTD) and elevated temperature wet (ETW) condition. Specimens were 38.1 mm wide with central through-holes ranging in diameter from 0.00 (unnotched) to 9.55 mm. The strain distribution near the hole in an OHT specimen was measured and found to agree well with that predicted for an infinite orthotropic plate subject to uniform remote stress. A simple modification of this model predicted well the strains near the hole on the tensile face of OHB specimens. OHT and OHC strength fell rapidly as hole size increased for small holes and less so for larger holes. This effect was much less pronounced in OHB specimens. The ETW environment had little effect on OHT properties but produced significant, and similar, reductions in OHC and OHB strength. OHT and OHC strength was predicted very well, and OHB strength moderately well, by the Whitney-Nuismer Average and Point Stress Criteria when using the strain distribution for that specimen type. OHC strength was also predicted very well by the Budiansky- Soutis-Fleck Cohesive Zone Model. However, each of these models requires experimental data in addition to the strength of the unnotched laminate and thus they are limited to applications where this data can be generated.