Mechanical property of single-bolted composite laminates

WANG Fu-sheng(王富生), WANG Pei-yan(王佩艳), JI Yao-yao(姬尧尧), LIU Zhi-qiang(刘志强), YUE Zhu-feng(岳珠峰)

(Advanced Materials Test Center, Northwestern Polytechnical University, Xi’an 710129, China)

Abstract:In order to investigate the effects of different geometrical parameters and pretightening loads on failure mode and bearing strength, a large number of single-bolted T300/QY8911 composite laminates were tested under static tension load. Box-plot was used to extract the singular testing values of bearing strength and effective statistical values were obtained. T-test method of independent samples was used to study how much pretightening loads influence bearing strength. The results show that the geometrical parameters, such as ratios of width to hole diameter (w/d) and edge distance to hole diameter (e/d), remarkably influence failure mode and bearing strength. Net-section failure will occur when w/d is smaller than 4, and shear-out failure will occur when e/d is smaller than 2. Bearing failure or bearing and shear-out combined failure will occur when w/d is greater than 4 and e/d is greater than 2. There is an optimal combination of geometrical parameters to achieve the highest bearing strength. For most of specimens, pretightening loads do not explicitly influence bearing strength.

Key words:single-bolted composite laminate; geometrical parameter; pretightening load; singular testing values; T-test method of independent samples