Thermal Residual Stress and Tensile Strength of UACS/Al Laminate with Different Slit Angles

Abstract

This paper focus on the investigation of tensile strength and thermal residual stress in UACS/Al laminates. The UACS (unidirectionally arrayed chopped strands) is made by cutting parallel slits on unidirectional carbon fiber prepreg. Thus all of the carbon fibers in the cut prepreg are 25 mm in length. Six cases of UACS prepregs are prepared with different slit angle θ, which is the angle between slit and fiber direction, including 5.7o, 11.3o, 16.7o, 31o, 45o and 90o. A UACS/Al laminate consists of one UACS layer with four UACS plies and two aluminum layers, such as [Al/UACS4/Al]. Four pieces of UACS prepreg with alternate slit angle [θ/-θ/θ/-θ] are stacked together in the same fiber direction. Then stacked UACS/Al laminate are cured using an autoclave. Tensile tests are performed to investigate the thermal residuals stress using the yielding-point-shift method. Experiment results show that thermal residual stress is reduced in the case of UACS/Al compared with conventional CFRP/Al. Among all the cases, specimen with slit angle of 11.3o is the most impressive one with 37.7% reduction of thermal residual stress.