The dielectrostriction effect for NDE of polymeric materials
Ho Young Lee, Yuri M. Shkel · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004
A novel approach for NDE of polymeric materials utilizing the dielectrostriction effect is presented. Any dielectric material exhibits dielectrostriction effect which is defined as variation of dielectric properties of the material with deformation. This phenomenon resembles well known photoelastic effect which has been widely used for NDE of transparent materials. The major difference is that dielectrostriction measurements can be conducted using a lower frequency than optical range of electromagnetic field. Thus, the dielectrostriction measurements can be administered to any, even non-transparent, material for in-line monitoring of strains and stresses. In addition, no mechanical contact is required for dielectrostriction measurements. Therefore, there is no problem with interface and attachment of the sensing element to the monitored part. A potential of dielectrostriction phenomenon for NDE is not completely explored at this time and would be the subject of future extensive studies. We will show its feasibility for monitoring undesirable features such as fatigue, cracks and residual stresses in dielectric materials. In this paper, we will present theoretical background and experimental data for dielectrostriction study of polymeric parts manufactured under various processing conditions.