Slow-brittle-fracture transition in polymethylmethacrylate

Theocaris, PS

dc.contributor.author	Theocaris, PS	en
dc.date.accessioned	2014-03-01T01:06:12Z
dc.date.available	2014-03-01T01:06:12Z
dc.date.issued	1983	en
dc.identifier.issn	0303-402X	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/9225
dc.subject	Caustics	en
dc.subject	Polymers	en
dc.subject	Slow-brittle-fracture	en
dc.subject	Toughness	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.classification	Polymer Science	en
dc.subject.other	MATERIALS TESTING	en
dc.subject.other	MATERIALS TESTING APPARATUS - Computer Applications	en
dc.subject.other	MATHEMATICAL TECHNIQUES	en
dc.subject.other	STRAIN	en
dc.subject.other	STRESSES	en
dc.subject.other	POLYMETHYL METHACRYLATE	en
dc.title	Slow-brittle-fracture transition in polymethylmethacrylate	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/BF01421436	en
heal.identifier.secondary	http://dx.doi.org/10.1007/BF01421436	en
heal.language	English	en
heal.publicationDate	1983	en
heal.abstract	A slow crack growth was achieved in initially edge-cracked specimens made of a high-molecular weight PMMA by regulating the cross-head speed of loading by a computer-driven testing machine. The strain rate {Mathematical expression} used during the tests varied between {Mathematical expression} =1× l0-6 s-1 and 1×10-4 s-1. It was shown that, in this zone of slow quasi-static loading of brittle polymethylmethacrylate specimens under conditions of plane stress, the crack initiated for a critical value of loading, at some characteristic zone of strain-rate variation at the crack tip. It was established that for strain rate between {Mathematical expression}=0.18×10-5 s-1 and {Mathematical expression}=0.45×10-4 s-1 brittle cracks were propagating always slowly with velocities in the range of c=3 to 5×10-2 m/s. For values of vs outside this transition zone fracture was typically brittle with high crack-propagation velocities. As the strain rate was varying beyond the stable low-velocity region, a two-step crack velocity pattern was operative, where the one step took always low values, and the other step corresponded to crack-propagation velocities significantly higher than these limits, tending to typical brittle-fracture velocities of the material. Oscillations of the velocity c at the transition zones, or, in many cases all over the zone of slow propagation of the crack, indicated the unstable character of crack propagation, influenced by different stress raisers and especially by the opposite longitudinal boundary of the specimen. Stress intensity factor values during crack propagation, evaluated from the front (cuspoid) and the rear (external) caustic, which remained always kg-dominant, were following similar trends as the variation of the crack propagation velocity. © 1983 Steinkopff.	en
heal.publisher	Steinkopff-Verlag	en
heal.journalName	Colloid & Polymer Science	en
dc.identifier.doi	10.1007/BF01421436	en
dc.identifier.isi	ISI:A1983RQ95300006	en
dc.identifier.volume	261	en
dc.identifier.issue	10	en
dc.identifier.spage	825	en
dc.identifier.epage	833	en