Abstract A method of controlling the thermal expansion of lightweight metals through the insightful incorporation of unidirectional carbon fiber reinforced polymer (CFRP) is demonstrated. The local and directional coefficients of linear thermal expansion (CLTE) of a carbon fiber composite reinforced aluminum (CFRP/Al) specimen can be controlled by tailoring the CFRP volume fraction and CFRP layup orientation, with a 36% reduction in CLTE achieved as compared to the baseline 7075 aluminum at a CFRP volume fraction of 0.26. When a unidirectional CFRP reinforcement is considered, the CLTE as predicted by the modulus modified rule of mixtures is within 1.3% of experimentally obtained values for CFRP volume fractions of 0.10, 0.16, and 0.26. Thermal digital image correlation (T‐DIC) was performed to obtain local and directional CLTE values for the anisotropic CFRP/Al specimens which indicated CLTE is heterogeneous across the specimen length and width, which is otherwise undetected using standard quartz rod dilatometry to measure the CLTE of the macroscopic sample. Evidence for a minimum critical CFRP reinforcement length is also considered based upon the local thermal strain data collected by T‐DIC. Using the mixed material approach presented here, it is possible to minimize or eliminate the thermal expansion mismatch effects that occur in mixed material structures, such as an automotive body structure (i.e., body in white).
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