Bent-beam

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).]... 

Fig. 3.33 Bent-beam test results in aerated distilled water. These specimens were exposed to the environment at a stress of 70% of yield (after Setterlund, Materials Protection, 4 No. 12,...

Further evidence of the relative resistance of maraging steel is reproduced in Fig. 3.33 from Reference 24. Maraging steel is shown to be superior to a die steel and low alloy steel (both unidentified) in bent beam tests stressed at 75% of the yield strength in distilled water. Also shown is the beneficial effect in smooth surface tests of cold rolling. Shot peening has a similar beneficial effect . 

Corrosion of metals and alloys stress corrosion testing. Part 2 Bent-beam specimens Corrosion of metals and alloys. Part 3 U-bend specimens... 

Bent beam samples (two-, three-, and four-point loading) in ISO 7539 Part 2, ASTMG538, NACE TM0177 Method B ... 

G39, Standard Practice for Preparation and Use of Bent-Beam Stress-corrosion Test Specimens, ASTM, West Conshohoken, PA, 1999. 

If the energy release rate of the bent beam is greater than a critical intrinsic toughness of the unpinned DCB, G/c, the delamination will propagate. 

The bending energy of a bent beam [Eq. (8.100)] then can be rewritten in terms of the Kuhn length ... 

Fie. 7.86 Relationship between yield strength and mean failure time for high-strength steels exposed as bent-beam tests in distilled wa-... 

FIGURE 2.23 Influence of the strength of longitudinal reinforcement on load-bearing capacity of bent beams in shear zones. (Reprinted from Yu. Potapov, O. Figovsky, Yu. Borisov, A. Polikushkin, and D. Beilin, Influence of Shear Force on the Behavior of Polymer Concrete Beams at Bend, J. Scientific Israel Technological Advantages 4, nos. 3-4 (2002) 25-31. With permission.)... 

Figure C. I Geometry of a bent beam, showing a fibre , a distance y above the neutral surface.

The standard testing for SCC has been reviewed by Sedriks [9] and Turnbull [10]. The following techniques have been used to estimate the SCC surface flawed, cantilever bend, creviced bent-beam tests, double cantilever beam, and compact tension specimens. 

Bend-beam specimens provide a quantitative estimate of the maximum stress in the outer fibers of the bent beam when stressed below the yield stress. Experimental standards for bent beam specimen are given in ASTM G 39-99 [16]. In this test, both the specimen... 

Fig. 9.4 Bend beams specimen used in constant-deformation test [16]. Reprinted, with permission, from ASTM G 39-99 Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens copyright ASTM International, West Conshohocken, PA.

G. Haaijer, A.W. Loginow, Stress analysis of bent-beam stress corrosion specimen. Corrosion 21 (1965) 105-112. 

The stress state in a bent beam is usually more complex than that encountered in pure bending, with non-uniform bending moments and shearing forces. In these cases, the normal stresses produced by the bending moment are still given by Eq. (4.6) but, in addition, shearing stresses t may be present such that... 

Electrothermal or Thermal Actuation Motion is generated by differential thermal expansion in materials such as sDicon or metals, while heat is typically injected into the actuator by means of Joule heat dissipation. Some actuator components expand more than others due to different cross-sections and therefore electrical resistance. Typical microactuator configurations include in-plane bimorph elements (Fig. 2a), out-of-plane bimorph plates, in-plane Chevron, or bent-beam elements (Fig. 2b) [3]. These types of actuators exhibit larger force capabiUties (in mN range), can achieve displacements of 100 pm or less but generally consume a lot of power (hundreds of mW), and have low bandwidth (Hz to KHz). Common methods of fabrication for electrothermal microactuators include surface micromachining... 

The theoretical explanation of these effects can be derived from the energy theory of fracture. Consider a crack as it just penetrates into a stiffer region of material, shown in Fig. 16.8. When the crack is at the interface, it exhibits the shape of a long bent beam under load. However, when the crack tries to penetrate into the stiffer material, there is more elastic resistance to bending deformation... 

ASTM D3929-03 Standard practice for evaluating the stress cracking of plastics by adhesives using the bent beam method. 

The theory of bent beams shows that variable curvature is accommodated by shear stresses, which are a maximum on the central plane. In fibres undergoing flex fatigue the.se shear stresses can cause failure by axial splitting. Fig. lOf.g. 

Evaluating the Stress Cracking of Plastics by Adhesives Using the Bent Beam Method, Practice for (D 3929)... 

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