Experimental Studies on Axial Bolted Joint between E Glass Epoxy Flat Laminate and Steel Flat Plates Subjected to Uni-Axial Tensile Repeated Loading for 15 Cycle

Abstract

Axial bolted joint between EN-31 steel flat plates and E-Glass Epoxy thick, flat laminate consisting of helical winding layers with ±30° helical angle of winding and fabric prepreg layers, was realised with 3 number of M10, 12.9 property class steel fasteners on each side and assembly was tested under uni-axial tensile repeated loading and unloading up to 8.1 ton proof load and to 0 respectively, for 15 cycle. Aim of the experiment was to study the damage induced if any and further increased, in E-Glass epoxy laminate near joint regions, under tensile repeated loading and unloading for 15 cycle. Total length, width and thickness of metal composite axial bolted joint test assembly were 700 mm, 150 mm, and 22 mm, respectively. Longitudinal and transverse strain was monitored at 31 strain gauge locations in composite laminate near joint regions, in all the 15 cycle. For first cycle, longitudinal strain was plotted during loading up to proof load of 8.1 ton and unloading to 0, to check the linearity of strain variation with increase and decrease in load, respectively. It was observed that strain at all strain gauge locations was varying linearly. Maximum strain measured was 4035 micro strain in 1st cycle. Residual strain at all strain gauge locations was observed very less. No defects were induced in composite laminate after 15 cycle.