Abstract
The sensitivity of the thermoelastic response to variations in the fibre volume fraction, resin material and manufacturing route is assessed. To quantify any effects a comprehensive materials testing programme has been conducted to obtain coefficients of thermal expansion, specific heat, density and the elastic properties, which is described in detail in the paper. The work is focused on attempting to ascertain if the source of the response is from the isotropic resin rich layer or from the orthotropic substrate. It is also demonstrated that small variations in material properties can have a significant effect on the calculated thermoelastic response.
Highlights
Thermoelastic stress analysis (TSA) [1] is a well established experimental technique based on the measurement of small changes in temperature on the surface of a cyclically loaded component
Where ∆T is the small thermoelastic temperature change, ∆σ1 and ∆σ2 are the stresses in the surface ply principal material directions, T is the absolute surface temperature, ρ is the density, Cp is the specific heat at constant pressure and α is the coefficient of thermal expansion (CTE) in the principal material directions
Since the resins used in composite materials are poor conductors, even a thin surface resin layer can act as a ‘strain witness’ [3, 4]
Summary
Thermoelastic stress analysis (TSA) [1] is a well established experimental technique based on the measurement of small changes in temperature on the surface of a cyclically loaded component. Where Q is the stiffness, J is a geometric transformation relating the principal material directions (1, 2) and global component (L, T) orientations and ∆ε is the change in strain in the laminate principal material directions. Since the resins used in composite materials are poor conductors, even a thin surface resin layer can act as a ‘strain witness’ [3, 4].
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