| 摘要 |
The method is used for testing materials, such as metals, alloys, ceramics and polymers used for the manufacture of parts, assemblies and units of machines and structures subjected to cyclic loads. It ensure greater precision at reduced number of tests. The method comprises subjecting the materials to cyclic fatigue at preset intervals of strains delta sigma = sigmamax - sigmamin measurement of length a of short or long fatigue cracks across a preset number of cycles of loading N and determination of the speed of growing of cracks da/dN and the interval of the coefficient of the strain intensity deltaK. From 6 to 10 measurements are made of the length of a long fatigue and from 10 to 15 of a short one for the determination of da/dN and deltaK, and linear dependence is constructed "of the speed of growing of the fatigue crack da/dN = a product of this speed and the interval of the intensity strain deltaK, represented as W = (da/dN)deltaK or kW = k(da/dN)deltaK", wherein k is normalizing constant of the kind k = Kmax (af), wherein: Nf is the end number of cycles in destruction, af - the end length of the main crack in destruction, Kmax(af) = Fsigmamax square root of pi a f - coefficient of the strain intensity at af and at maximum strain of the strains interval delta sigma = sigmamax-sigmamin, where the test is made, F is a factor depending on the geometry of the standardized specimen. 2 claims, 8 figures
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