Modelling the electrical resistance of multidirectional laminates with off-axis cracks

In this work, an analytical model is developed to calculate the electrical resistance of a conducive symmetric multidirectional laminate with cracks in multiple layers. To this end, initially, an analytical solution is derived for laminates with cracks in a single layer and, subsequently, the case of cracks in multiple layers is treated using a superposition approach. The accuracy of the analytical model is checked by comparison with the results of several numerical analyses. Later on, the electrical model is used in combination with an existing stiffness degradation model, documenting that a well-defined correlation does exist between the electrical resistance and the stiffness loss of a multidirectional damaged laminate. This allowed damage charts to be drawn, that can be used to assess the stiffness degradation of composites based on electrical measurements.