Friction stir blind riveting of carbon fiber-reinforced polymer composite and aluminum alloy sheets

Abstract

A friction stir blind riveting (FSBR) process is used to fabricate joints of carbon fiber-reinforced polymer composite (CFRP) and aluminum alloy AA6111 sheets in a lap shear configuration. Given the 9,000 rpm spindle speed upper limit of conventional computer numerically controlled machines, the maximum feed rate for FSBR joining CFRP to itself is found to be 120 mm min −1 above which quality issues such as cracking of the CFRP sheet predominate. However, the maximum feed rate during dissimilar joining of CFRP to AA6111 can be 420 mm min −1 when the CFRP top sheet is supported by the AA6111 bottom sheet. The maximum lap shear tensile load of the joints shows little dependence on the spindle speed and feed rate during FSBR. The different stack-up sequences of the CFRP and AA6111 lead to different maximum loads, displacements to fracture, and locations of fracture initiation, i.e., in the CFRP vs. in the AA6111.

Unveiling 3D Deformations in Polymer Composites by Coupled Micro X-Ray Computed Tomography and Volumetric Digital Image Correlation

“…Prior studies revealed that CFRP in FSBR joints failed near the rivet hole, suggesting that the stir-affected zone possessed distinct mechanical properties [3]. As the strength and stiffness of fiber-reinforced composites is intimately related to fiber volume, porosity and fiber orientation, we explored these parameters near the rivet hole in the stir-affected zone and compared these values to the bulk material.…”

“…The reconstructed images captured at 0, 22 and 44 MPa compressive loads were correlated using commercial V-DIC software (Vic-Volume v1.09, Correlated Solutions Inc.) to calculate the full-field displacement and strain tensors using subset size of [35 voxels] 3 and subset spacing of 15 voxels (equivalent to [47 μm] 3 and 20 μm, respectively). Fibers, pores and other microstructural features with pseudo-random orientation, size and location provided an intrinsic high-contrast speckle pattern for displacement calculations.…”

“…Dissimilar material joining techniques, including friction stir welding [1], friction stir blind riveting [2,3], adhesive joining [4], and laser welding [5,6], all locally alter microstructure and mechanical properties, introducing complex threedimensional (3D) anisotropic deformation behavior that is not yet well understood at a microstructural level. Conventional in-situ microstructure and deformation studies are usually performed in a 2D fashion by imaging either sample surfaces or cross sections when the sample is subjected to mechanical loading, which alternately fail to capture internal deformation or provide real-time data.…”

Joining of Carbon Fiber Reinforced Plastic to Aluminum Alloy by Reactive Multilayer Films and Low Power Semiconductor Laser Heating

“…A number of joining methods have been used for joining CFRP-aluminum alloys, such as adhesive joining [3], friction stir joining [4], ultrasonic joining [5] and laser joining [6]. Adhesive joining is a conventional process for joining plastics, including CFRP to metals [7].…”

Effect of Atmospheric Pressure Plasma Treatment on the Lap-Shear Strength of Adhesive-Bonded Sheet Molding Compound Joints

“…Sheet molding compounds (SMCs) have gained extensive use in the area of new-energy vehicles to realize the light-weight requirements thereof [1,2]. However, a method whereby to joint the SMC substrates to ensure adequate automotive safety becomes important as the number of joining demands increases [3].…”