Precracked cantilever beam specimens

The components of a precracked beam test are shown in Fig. 9.14 [9]. The precracked cantilever beam specimen is used to estimate stress susceptibility in the presence of stressraising defects in the precrack sample. Plane strain stress intensity factor K is calculated using Eq. (9.15) ... 

Fig. 9.15 (a) Calculation of K, for a precracked cantilever beam specimen. M, represents bending moment, (b) K scc illustration of a time to failure plot in the determination of Kissc P]. NACE International 1990. 

J. Sedtiks, Making and using precracked cantilever beam specimens, in Stress Corrosion Cracking Test Methods, National Association of Corrosion Engineers (NACE), Houston, TX, 1990, pp. 37 5. 

The effect of test duration is demonstrated fqr a method used fy the Navy to compare materials for aircraft parts. A single-edge notched (and precracked) cantilever beam specimen is deadweight loaded and exposed to 3 1/2 % NaCl. The time-to-fad at various stress intensities is plotted in Fig. 8. The stress intensity after 1000 h exposure has been used as a measure of resistance, although lower values have been obtained if the specimens are allowed to continue for 10 000 h. 

RG. 8—see results for single-edge notched and precracked cantilever beam specimens of UNS K92580 (52 HRe) in 3.5 % Naei at room temperature. 

FIG. 28-18 Specimens for stress-corrosion tests, (a) Bent beam, (h) C ring, (c) U Lend, (d) Tensile, (e) Tensile, (f) Tensile, (g) Notched C ring, (h) Notched tensile. ( ) Precracked, wedge open-loading type. (/) Precracked, cantilever beam. [Chem. Eng., 78, 159 (Sept. 20 1971).]... 

Category 2 tests are fracture mechanics tests that use notched and precracked specimens that are statically or dynamically loaded, such as cantilever beam, compact tension, and double cantilever beam specimens, and are conducted per ASTM E 399, Test Method for Plane-Strain Fracture Toughness of Metallic Materials. 

D.O. Sprowls and J.D. Walsh, Evaluating Stress-Corrosion Crack Propagation Rates in High Strength Aluminum Alloys with Bolt Loaded Precracked Double Cantilever Beam Specimens, Stress-Corrosion—New Approaches, STP 610, H.R Craig, Jr., Ed ASTM, 1976, p 143-156... 

The equipment required for slow strain-rate testing is simply a device that permits a selection of deflection rates whilst being powerful enough to cope with the loads generated. Plain or precracked specimens in tension may be used but if the cross-section of these needs to be large or the loads high for any reason, cantilever bend specimens with the beam deflected at appropriate rates may be used. It is important to appreciate that the same deflection rate does not produce the same response in all systems and that the rate has to be chosen in relation to the particular system studied (see Section 8.1). 

This test method can be used to measure the relative susceptibility of materials by "Determining the Threshold Stress Intensity Factor for Environment-Assisted Cracking EAC of Metallic Materials. Constant load specimens, both the fatigue precracked single edge beam SE(B) and precracked compact specimens are tested in bending. The SE(B) was originally referred to as the Cantilever Beam Test. 

The double-cantilever-beam (DCB) test uses fracture mechanics techniques to evaluate the SSC resistance of tuhular steels [7]. It employs a 9.5 by 25 by 100 mm (0.375 by 1.0 by 4.0 in.) specimen with side grooves and loaded with a double taper wedge. In some cases, the specimen is precracked. Typical test duration is 14 days. 

Category 2 notched and precracked specimens such as cantilever beams, compact tension specimens, and double-cantilever beams (ASTM E 399)... 

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