Crack-Size Measurement of Additive Manufactured Plastics Based on the DCPD Method

Abstract

Abstract Additive manufacturing offers the possibility of producing novel plastic products, which can be unique and complex, especially when the use of load-bearing components leads to a periodic load. Therefore, plastic components must also be examined for a sufficient service life. The aspects of crack initiation and crack propagation are particularly important. In this regard, a significant parameter is the crack propagation curve, for whose determination a continuous crack-size measurement is required. This article addresses how far the Direct Current Potential Drop (DCPD) method can be applied on additive manufactured plastics in order to make a statement about the fracture mechanical behavior of the materials. For this reason, the surfaces of compact tension (CT) specimens were coated with an electrically conductive layer using two different coating methods. Referring to this, experimental investigations were carried out in regard to the applicability of the DCPD method. Overall, two different coating methods were tested with experimental investigations. The experiments showed that the methods of galvanization and specimen coating enabled the application of the DCPD method to additive manufactured plastics. Furthermore, fracture mechanical investigations were carried out. In this context, crack propagation curves were determined by using both methods, and typical fracture mechanics parameters, e.g., threshold value, ΔKI,th, and stress-intensity factor at unstable crack propagation, ΔKIC, were identified.