Recent Development of Planar Cruciform Experiment on Biaxial Tensile Deformation and Failure of Unidirectional Glass/Epoxy Composite

Abstract

Inadequate experimental characterization of strength and deformation behavior of unidirectional fiber composites under planar biaxial stresses has hindered the development of complete material models. Here the recent development of a cruciform specimen with unidirectional gage section is presented, suitable to test glass/epoxy under combined high transverse and longitudinal tensile loads. The experimental program developed comprises of six different biaxial tensile load ratios. The results show significant influence of longitudinal stress on transverse nonlinearity of a glass/epoxy. Failure loci and failure modes in biaxial tensile strain and stress domains are presented, indicating a reduction of transverse strength by high longitudinal loads.

Understanding the effect of anisotropy in composite materials on the performance of cruciform specimens

“…• Type 2: Geometries with a regular corner radius and a reduced central gauge zone thickness but with slotted arms [25,29,28,27] as a suggestion to promote adjacent arm decoupling as well.…”

“…But there is no consensus on the best shape independent of the layup configuration and the biaxial loading ratio. Moreover, cruciform specimens have also been investigated with slots in the arms [25,27,28,29,22] (as found in metallic cruciform specimens [2,3,4,30,31,6,32,7,8]) and by changing the shape of the corner formed by the adjacent arms [16,13]; all with the goals of directing the entire load applied at the arms towards the gauge zone and to further improve the uniformity of the stress state in the gauge zone.…”