Novel method for measurement of pipeline materials fracture resistance-examination on selective laser sintered cylindrical specimens

Abstract

This paper presents a part of development of a non-standard method for testing of cylindrical test specimens for measurement of fracture properties of pipeline materials. This method for testing of cylindrical structures working under pressure is based on determining of fracture mechanics parameters on SENT (Single Edge Notched Tension) specimens and new PRNT (Pipe Ring Notched Tension) specimens. In this work, both types of specimens required for this testing were manufactured from polyamide PA12 by using SLS (selective laser sintering) additive manufacturing method. Testing of the specimens is performed on the universal device for testing of mechanical properties of materials Shimadzu, AGS-X 100 kN. The tensile testing is accompanied by GOM Aramis 2M system, used for digital image correlation. By using these two systems, test results are obtained for ring-shaped and SENT specimens, including forces, displacements and fracture mechanics parameters CMOD (Crack Mouth Opening Displacement) and CTOD-?5 (Crack Tip Opening Displacement obtained by ?5 technique), as well as crack growth. Repeatability of this process, along with valid result consistency, represent the basis for further development of the new method, including the determining of energy-based fracture mechanics parameters: J integral and stress intensity factor.