What exactly does ASTM E399 test?

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Accepted Answer

ASTM E399 defines the test conditions to determine the fracture toughness value KIC under linear elastic conditions. What makes it unique: Standardized specimens are used – usually CT (compact tension) or SEB (single edge bend) specimens – which specifically contain predefined cracks. These are led to fracture under quasi-static loading, whereby the stress intensity at the crack is evaluated. The prerequisites for valid results are: A linear elastic material behaviorA "natural" crack with certain properties (i.e. sharp with a certain crack length and defined preceding stress field)A precisely controlled test procedureA careful evaluation compliant to standard specifications And this is exactly where it becomes clear: ASTM E399 is anything but a simple standard test. The demands on the machine, software and user are high – and the time required for many specimens can be significant.