Using Compliant Interlayers as Crack Arresters in 3-D-Printed Polymeric Structures
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The aim of this study is to show the influence of using compliant interlayers as crack arresters for three-dimensional (3-D)-printed polymeric structures. To investigate the effectiveness of compliant interlayers, specimens consisting of a stiff and brittle matrix and thin compliant interlayers were printed. The results of these polymeric composites were compared to pure matrix material samples. To generate specimens, a commercially available material extrusion-based desktop 3-Dprinter was used. Additively manufactured samples were tested in both impact as well as fracture mechanical tests. The application of a compliant interlayer as crack arrester showed high potential in both types of test. Instrumented Charpy impact tests according to EN ISO 179-2 revealed an increase of notched impact strength from 5.0 ± 0.1 kJm−2 to 25 kJm−2 (energy up to Fmax) and 136 ± 2.6 kJm−2 (total energy during testing), respectively. This indicates an increase of roughly 725% and 2,720%, while the maximum force during testing remained almost unchanged at approximately 200 N. Interestingly, the exact position as well as the number of compliant interlayers did not show a significant influence on the results. Therefore, tests that are more detailed were conducted on specimens including only a single interlayer. Further tests consisted of J-integral testing on specimens with aforementioned single compliant interlayers. Crack resistance (J-R curves) were generated using the multi-specimen approach and evaluation according to the protocol of the European Structural Integrity Society. Although a special data-shifting procedure has to be applied to interpret results more clearly, J-integral values showed a significant increase of 250 % at the interface between materials compared to the pure matrix material.