On the maximum curvatures of 0/90 plates under thermal stress

The paper focuses on the behaviour of 0/90 plates subjected to thermal stress and free from mechanical loads. Curvatures arising from the temperature differential are regarded as functions of the relative thickness of the 90° ply, e90: it is found that curvatures are maximum for a certain value of e90, the position and the absolute value of such maximum depend on the elastic and thermoelastic properties of the ply and their invariant quantities. More precisely, the position of the maximum is affected by the elastic properties only, the magnitude of the maximum is affected very little by the elastic properties and is driven by the thermoelastic properties, i.e., the coefficients of thermal expansion of the ply. This paper represents a first effort towards the complete identification of laminates which maximise the out-of-plane deflections, i.e., curvatures, under hygro-thermal loads: the problem is posed in a general fashion, foreseeing further developments.