Strength specimen size

Lateral Expansion Requirements. Other carbon and low alloy steels having specified minimum tensile strengths equal to or greater than 656 MPa (95 ksi), all bolting materials, and all high alloy steels (P-Nos. 6, 7, and 8) shall have a lateral expansion opposite the notch of not less than 0.38 mm (0.015 in.) for all specimen sizes. The lateral expansion is the increase in width of the broken impact specimen over that of the unbroken specimen measured on the compression side, parallel to the line constituting the bottom of the V-notch (see ASTM A 370). 

Figure 4. Variation in compressive strength with specimen size for raw sulfur and a sulfur pyrrhotite concrete mean and standard deviation of...

Malhotra, V. M., Effect of Specimen Size on Compressive Strength of... 

We can predict the impact behavior, namely impact strength and fracture mode, over a wide range of temperatures independent of specimen size by using standard specimens. 

A further and very important consequence of the Weibull distribution is the size effect, i.e. the mean strength decreases with increasing specimen size. This is the most important consequence of fracture statistics for designing with ceramics. 

Soutis C, Lee J. Measuring the notched compressive strength of composite laminates specimen size effects. Compos Sci Technol 2008 68(12) 2359—66. 

These include the magnitude of the residual stress, the particle size and the size (and shape) of defects within the residually stressed regions. Similar to transformation toughening, a toughening limit is expected if the microcrack zone size approaches the specimen size and a yield-limit to the strength will occur. 

Figure 9.1 Effect of various factors on strength distribution a) specimen size b) loading geometry and c) multiax-ial loading.

This has been demonstrated for a commercial glass ceramic [38], and for alumina [39]. It has been suggested that the microstructure and the defect populations themselves may vary throughout the volume of a component, causing variations in strength unpredictable by Weibull analysis [40,41]. An attempt to verify the minimal specimen size required for strength determination was carried out lately [42]. 

All elastic moduli were determined using deflection measurements in 3-point bending tests at Societe Fran9aise de Ceramique in Paris (specimen size 110x10x8 mm), whereas some of the strength measurements were performed at C.R.E.E. (Saint Gobain Ceramiques Industrielles research centre) in Cavaillon (specimen size 150x25x25 mm). Tables III and IV summarise the obtained results. 

G.K. Bansal and W.H. Duckworth, Effects of Specimen Size on Ceramic Strength, in Fracture Mechanics of Ceramics (1978), 3, p. 189 edited by R.C. Bradt, D.P.H. Hasselman and FT. Lange, Plenum Press, New York. 

Cui WC, Wisnom MR, Jones M, Effect of specimen size on interlaminar shear strength of unidirectional carbon fiber-epoxy. Composites Eng, 4(3), 299-307, 1994. 

Wisnom MR, The effect of specimen size on the bending strength of unidirectional carbon fiber-epoxy, Composite Structures, 18(1), A1-G3, 1991. 

Figure 20.14 Effect of specimen size on fiexurai strength. Source Reprinted with permission from Wisnom MR, The flexural strength of unidirectional carbon fibre epoxy, 5th European Conference on Composite Materials, Elsevier, Bordeaux, 165-170, 1992. Copyright 1992, Sage Publications.

A number of workers have published results on cfrp using the losipescu test [55], 4- point shear test [56], effect of specimen size [57], effect of strain rate [58], in-plane shear test [59], shear strength of pultruded product [60], rail shear test [61] and torsion test [62,63],... 

For compressive strength determination, ASTM D695 and D649 use a molded or machined specimen for a specified slenderness ratio. The specimen is compressed in a suitable test machine at a specified loading rate, generally 0.05 in./min until failure occurs. A wide range of specimen sizes is permitted for this test... 

Specimen size, in general, has an effect on mechanical tests, and ceramics or glasses are no exception. The shapes of ceramic and glass test specimens are often a matter of convenience, but, in most cases, the specimen s form dictates the test conditions. Various other techniques have also been suggested to improve the reliability of the strength result. One such technique, used for the tensile testing of ceramic fibers, is video extensometry [25]. Figure 1.8 illustrates a schematic video set up for the evaluation of the results of SiC monofilaments. 

Fig. 5.63 Strength-grain size relationship (a) and subcritical growth of radial indentation cracks (b) of sintered batches selected from Fig. 5.62. Straight lines are least squares fits. Strength ranking numbers associate specimens in (b) to batches in graph (a), numbers 1-3 are consistent with Table 5.2 and Fig. 5.62 [20]. With kind permission of Elsevier...

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