Rishabh Bhupathi
Independent Researcher
India
Abstract
This manuscript presents a detailed finite-element analysis of thermal stresses induced in bimetallic strips subjected to transient and steady‐state temperature gradients using ANSYS Workbench 14.5 (2015). Bimetallic strips, widely used in thermostatic devices and mechanical relays, consist of two metals with differing coefficients of thermal expansion (CTE) bonded together. Under temperature change, differential expansion generates internal stresses that influence strip curvature, fatigue life, and operational reliability. The study develops 2D and 3D numerical models, validates them against analytical solutions for simple geometries, and applies realistic boundary conditions representative of industrial applications. Key parameters such as strip thickness ratio, material pairing (brass–steel and copper–steel), and heating rates are varied to quantify stress distributions and deformation characteristics. Results demonstrate that maximum von Mises stresses occur at the bimaterial interface and depend strongly on thickness ratio and imposed temperature ramp. Two industrial case studies—an HVAC thermostat sensor and a circuit‐breaker trip mechanism—illustrate practical implications. Recommendations for design optimization, including material selection and dimensional tuning, are provided to minimize stress concentrations. This work contributes to improved reliability and life‐cycle performance of bimetallic components in engineering systems.
Keywords bimetallic strip, thermal stress, ANSYS, finite‐element analysis, coefficient of thermal expansion
References
ASM International. (1990). ASM Handbook, Volume 1: Properties and Selection: Irons, Steels, and High‐Performance Alloys. ASM International.
Beer, F. P., Johnston, E. R., DeWolf, J. T., & Mazurek, D. F. (2009). Mechanics of Materials (6th ed.). McGraw‐Hill.
Callister, W. D., & Rethwisch, D. G. (2013). Materials Science and Engineering: An Introduction (9th ed.). Wiley.
Cook, R. D., Malkus, D. S., Plesha, M. E., & Witt, R. J. (2007). Concepts and Applications of Finite Element Analysis (4th ed.). Wiley.
Dowling, N. E. (2013). Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue (4th ed.). Pearson.
Timoshenko, S. (1925). Analysis of Bi‐metal Thermostats. Journal of the Optical Society of America, 11(3), 233–255.
Zhang, J., & Li, Q. (2012). Thermal‐Mechanical Behavior of Bimetallic Strips in Thermostatic Devices. International Journal of Mechanical Sciences, 65, 149–158.
Singh, R. P., & Kumar, A. (2014). Finite Element Analysis of Thermal Stresses in Bimetallic Elements. Journal of Engineering Materials and Technology, 136(2), 021014.
Patel, S., & Sharma, V. (2010). Design Optimization of Bimetallic Strips for Improved Sensitivity. Materials and Design, 31(6), 2872–2879.
Wang, X., & Chen, M. (2015). Fatigue Analysis of Bimetallic Thermostatic Elements Under Cyclic Thermal Loading. Journal of Thermal Stresses, 38(4), 481–497.
