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Thermoelastic Stress Analysis and Modelling for Mechanical Property Assessment of Composite Materials



Thermoelastic Stress Analysis (TSA) is a full-field stress measurement technique that has proven effective for experimentation with metallic alloys. In addition, its recently improved portability has facilitated application to built-up aircraft structure as well. This has led to an interest in applying the method to composite airframes. Since the thermoelastic response is more complex in layered orthotropic materials, it is not possible to relate measured temperature to stress without a model to facilitate the conversion. The current study comprised experimentation and thermomechanical (multi-physics) analysis of tension loaded open-hole notch specimens using aluminium and composite laminates typical of use on fifth generation fighter aircraft. The results confirmed the accuracy of TSA for measuring stress in isotropic metallic materials. The results for the composite materials show that the thermoelastic response is sensitive to a range of conditions, including natural volume fraction variation across the surface ply. The predictions, however, compared reasonably well with the experimental results. The work provides a new tool for realizing the goal of using TSA for in-situ measurement of stress on composite airframes. It also provides a basis for understanding current limitations as pertaining to its use on composites and areas where development needs to be focused.


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