Optimization of Metal-to-Composite RIVTAC Joints
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Date
2023-05
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Publisher
The Ohio State University
Abstract
Composite materials offer automotive companies an opportunity to save weight on vehicles by replacing metals. However, composites cannot be welded, so mechanical fasteners, adhesives, or a combination of the two must be used to fasten materials together. Mechanical fasteners introduce stress concentrations and damage to composites, so this study seeks to quantify the damage done to composites by RIVTAC fasteners and the effects of repairing this damage with adhesive, define an optimal method for applying adhesive into the joint, and determine if preventing or repairing this damage increases the joint strength.
The first step in this study was creating a finite element model that could validate future experiments. This model connected a woven carbon fiber plate with a 6061-T6 aluminum plate using an abstraction for a RIVTAC fastener in a single lap configuration. The mesh consisted of tetrahedral elements of 1.1 mm on the plates and 1.5 mm on the fastener. Plasticity was modeled with a bilinear isotropic hardening condition. This configuration was then subjected to a fixed displacement of 4 mm on the edge of the aluminum plate with a fixed support on the edge of the carbon fiber plate. The RIVTAC abstraction used bonded constraints on the top and bottom edges of the plates and frictionless contact conditions between the face of the fastener and the faces of the holes in the plates.
The finite element model correctly predicted bearing failure in the composite plate. This suggests that the model can be used to predict experimental results and therefore validate design choices. The model also showed a linear relationship between fastener angle and horizontal displacement, with a maximum rotation of 14.5699°. This suggested that fastener over-rotation is a failure mode that can be designed for in future experiments using this configuration.
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Keywords
Composites, RIVTAC, Finite Element Analysis, Automotive