Joint Configuration of Composites with Metals for High-Temperature Applications Through Thermal Stress-Free Fastener

In high-temperature applications, dissimilar materials are joined to meet the thermal and structural requirements. The criticality of joint configuration is imposed to eliminate the thermal stresses at the interface due to its differential rates of linear thermal expansion coefficients of materials. One of the novel approaches to designing joints is by incorporating an engineered configuration of the fastener, which reduces or eliminates the stresses generated at those joints. However, considering the wide spectrum of materials in high-temperature composites (C–C, C–SiC, C/C–SiC, SiC–SiC) which are candidate materials, the approach needs further study. The present study employs the thermal stress-free fastener concept by joining INCONEL 617 with 2D C–C composite. The 2D C–C composites are one of the most prominent materials for high-temperature applications in re-entry and hypersonic vehicles. However, the composite material inherits a very low orthotropic thermal expansion coefficient than conventional material, resulting in high thermal stresses. A state-of-the-art thermal stress-free fastening technique is employed to reduce thermal stresses by suitably configuring the fastener. The mathematical formulation for thermal stress-free boundary and typical fastener shapes has been proposed. FEA simulations were employed to capture the aero-thermal environment of typical re-entry and hypersonic vehicle joint configuration.