transient distortion coefficient – A measure of the “time for a thermal distortion to dissipate per unit of temperature gradient” (ref), equal to the coefficient of thermal expansion, α, over the thermal diffusivity, D. It has units of s/(m2∙K).
Material properties and thermal properties in particular tend to vary with temperature. As a derived property of two thermal properties, the transient distortion coefficient is highly variable.
The transient distortion coefficient is a figure of merit used for evaluating materials and is not typically used in calculations. Hence, it is not assigned a symbol.
transient distortion coefficient = coefficient of thermal expansion / thermal diffusivity = α / D