Predicting winding stresses for wound coils of non-linear orthotropic material

Abstract

In another work, the authors presented an analysis of stresses in wound coils under the assumption that the coil could be modelled as an orthotropic linear material. In this paper the authors extend the theory to the case where the constitutive relations of the coil material are non-linear. The approach adopted for both the linear and non-linear theory differs radically from that usually reported in this field of research. Instead of the traditional ‘forward solution’ of calculating stresses for a given winding policy, an ‘inverse solution’ is obtained in which the winding stresses required to achieve specified stress distributions in a coil are calculated. Stress distributions required to avoid coiling problems can often be specified. This method can therefore offer considerable advantages in industrial applications, since winding stresses required to achieve a specified stress distribution in a coil can be calculated directly. The non-linear solutions are compared to those for the linear case for different winding stresses and coil properties. An example of the effect of modifying the stress distribution in a coil on the winding stress is given to illustrate the advantage of this method.