@misc{bucknall_structure_processing_2020, 
author={Bucknall, C., Altstädt, V., Auhl, D., Buckley, P., Dijkstra, D., Galeski, A., Gögelein, C., Handge, U., He, J., Liu, C., Michler, G., Piorkowska, E., Slouf, M., Vittorias, I., Wu, J.},
title={Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 4: sporadic fatigue crack propagation},
year={2020},
howpublished = {journal article},
doi = {https://doi.org/10.1515/pac-2019-0408},
abstract = {Fatigue tests were carried out on compression mouldings supplied by a leading polymer manufacturer. They were made from three batches of ultra-high molecular weight polyethylene (UHMWPE) with weight-average relative molar masses, ¯¯¯¯MW, of about 0.6 × 106, 5 × 106 and 9 × 106. In 10 mm thick compact tension specimens, crack propagation was so erratic that it was impossible to follow standard procedure, where crack-tip stress intensity amplitude, ΔK, is raised incrementally, and the resulting crack propagation rate, da/dN, increases, following the Paris equation, where a is crack length and N is number of cycles. Instead, most of the tests were conducted at fixed high values of ΔK. Typically, da/dN then started at a high level, but decreased irregularly during the test. Micrographs of fracture surfaces showed that crack propagation was sporadic in these specimens. In one test, at ΔK = 2.3 MPa m0.5, there were crack-arrest marks at intervals Δa of about 2 μm, while the number of cycles between individual growth steps increased from 1 to more than 1000 and the fracture surface showed increasing evidence of plastic deformation. It is concluded that sporadic crack propagation was caused by energy-dissipating crazing, which was initiated close to the crack tip under plane strain conditions in mouldings that were not fully consolidated. By contrast, fatigue crack propagation in 4 mm thick specimens followed the Paris equation approximately. The results from all four reports on this project are reviewed, and the possibility of using fatigue testing as a quality assurance procedure for melt-processed UHMWPE is discussed.},
note = {Online available at: \url{https://doi.org/10.1515/pac-2019-0408} (DOI). Bucknall, C.; Altstädt, V.; Auhl, D.; Buckley, P.; Dijkstra, D.; Galeski, A.; Gögelein, C.; Handge, U.; He, J.; Liu, C.; Michler, G.; Piorkowska, E.; Slouf, M.; Vittorias, I.; Wu, J.: Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 4: sporadic fatigue crack propagation. Pure and Applied Chemistry. 2020. vol. 92, no. 9, 1521-1536. DOI: 10.1515/pac-2019-0408}}