The focus of the PhD-project is on the investigation of piezo-electric multi-phase composites which consist of piezoelectric particles imbedded into epoxy resin. The particles convert the elasto-mechanic deformation energy into electrical energy. Thus, the composites are suitable to be applied as energy-converting layers in fiber reinforced polymer composites. The electro-mechanic properties of these multi-phase composites shall be modelled for a better understanding of their permittivity properties starting from a micro scale up to a coupon level. Resin additives enhancing the permittivity shall be considered as well.