PRENDOICTTCIHOEND OF FRACTURE STRENGTH FOR LCAOMMINPARTEES SSIUOBNJ ECTED TO LOA DING

摘要

Two previously developed failure criteria (the average stress failure criterion and the point stress failure criterion), which are used to predict the uniaxial compressive strength of a laminated composite containing through-thethickness material discontinuities (notches), are subjected to further experimental scrutinization. This paper contains predictions, using the two failurecriteria, for compressivefracture strength in open hole laminates. This is accomplished by obtaining experimental data on the carbon/epoxy material system, in conjunction with unnotched multidirectional laminates and open hole multidirectional laminates. The composite material used in this paper is a carbon/epoxy unidirectional (UD) tape prepreg (Cycom G40- 800/5276-1) cured at a 350°F (177°C). The operating temperature is -60°F ~ +200°F (- 55°C~+95°C). A total of 84 compression tests were conducted on specimens from 6 distinct laminates that were laid up by standard angle layers (0°, +45°, -45° and 90°). The ASTM-D- 6484D standard was used for the test method. Results are presented for the fracture compressive strengths of several carbon/epoxy laminates containing a circular hole. The point stress failure criterion was more reasonable than the average stress failure criterion to predict the observed strengths in all cases considered.