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Mixed Mode Fracture Mechanics Behaviour of PMMA
Author(s) -
Lach Ralf,
Grellmann Wolfgang
Publication year - 2017
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201600108
Subject(s) - crazing , materials science , fracture toughness , composite material , fracture mechanics , fracture (geology) , mode (computer interface) , mixed mode , ultimate tensile strength , brittleness , stress (linguistics) , stress intensity factor , polymer , linguistics , philosophy , computer science , operating system
Summary The mixed mode brittle fracture (mode I/mode II) of poly(methyl methacrylate) (PMMA) was investigated using single‐edge notched tensile (SENT) specimens by applying a mixed mode special loading device which allows varying the loading angle from 0° (pure mode I) to 90° (pure mode II). The experimental results dealing with mixed mode fracture toughness and initial angle of crack propagation are in good agreement with predictions based on a modified criterion of maximum tangential stress (MTS criterion) where non‐singular stresses ( T stresses) are considered. These additional T stresses are the reason why distinct fracture by normal stress with crazing is always macroscopically observed in PMMA under the selected loading conditions including pure external mode II loading. Therefore, the length of the craze zone, i.e. the process zone, has been determined to be about 0.5 mm independent of the loading angle. It has to be pointed out that the fracture surface morphology should be kept in mind more often in future for assessing the mixed mode fracture mechanics parameters.