Bend-beam 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.

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

For linear elastic materials, deflection at the load-point of a four-point bending beam is given by two different contributions, accounting for both bending and shear deformation. In the case of notched specimens, a third term accounting for crack length arises. The resulting analytical expression for the specimen compliance C is as follows ... 

Experimental investigations to find the influence of polymer coatings on the strength of concrete and reinforced concrete beams at bend was continued with three series of concrete test specimens (B, Bl, and B3) measuring 3 x 6 x 64 cm, and two series of reinforced concrete beam specimens (BO, BP) measuring 10 x 20 x 160 cm. The polymeric coating compositions were EA-20-100 , PEPA-10 , andesite-100 . 

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. 

Bending strength were measured in the three-point bending test on beam specimens of dimension 40x40x160 mm (distance between supports was 100 mm) and compressive strength were measured in the axial compression test on specimens of dimension 40x40x40 mm. 

These results can be compared to the same set of results obtained from the study on beam specimens (SLCOl and SLC02) in Section 8.2, which were subjected to four-point bending during 60 and 120 min fire exposure from the underside, see Table 8.6. In the former study, six-cell specimens were used in contrast to the four-cell specimens used here. The bending stiffnesses obtained from Section 8.2 were therefore corrected by a factor of 4/6 in order to make them comparable. At the end of fire exposure, the bending stiffness of the still-hot specimens (SLCOl/02) dropped to 46% and 43% of the initial value, which almost matched the values obtained for the column specimens. The post-fire stiffnesses (64% and 60%), however, were slightly lower than those of the column specimens (76% and 70%). 

Four-point bend tests were performed at room temperature and at 1400°C. All bending tests had an upper span of 10 mm and a lower span of 30 mm. An Instron-type universal tester was used for bending tests, with a constant cross head of 0.2 mm/min. Figure 5.36 shows the dimensions and coordinate system of the beam specimen with ground surface in a four-point bend test. 

Three-Point Bending Test of Notched-Beam Specimens... 

The bending beam rheometer (Figure 4.21) is composed of a loading frame with test specimen supports, a controlled low/very low temperature liquid bath that maintains the test specimen at the test temperature and provides a buoyant force to counterbalance the force resulting from the mass of the test specimen and a computer-controlled data acquisition system for the execution of the test and the processing of the results. 

With regard to American practice, fatigue test is performed according to ASTM D 7460 (2010) or AASHTO T 321 (2011). The standard specifies one procedure/test method, the four-point flexural bending test on prismatic (beam) specimens. 

Some beam specimens were fabricated whose flanges and webs were spliced at mid-span in a similar way to Fig. 8.13. The performance in four-point bending was encouraging, although yield in the aluminium alloy was rarely experienced. 

Under three point bend loading of a composite (beam), cracks may be developed due to tensile stresses at the lower stratus of the specimen as well as compression stresses at the upper one, or due to interlaminar shear. The type of failure depends on the ratio of span to depth (L/D). Short beam specimens usually fail in shear and long ones by tensile or compression stresses. For interlaminar shear strength (ILSS) tests, a L/D = 5 was chosen (ASTM-D-2344-76). In case of flexural strength tests, this ratio was fixed to 40 (DIN 29971). 

Three-point bending on an X-aerogel beam specimen allows measurements of flexural modulus and strength. The ASTM standard D790 (Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials) specifies a length/width ratio of 16. The stress [Pg.509]

Three-point bending tests on X-aerogel beam specimens with nominal dimensions of 8.6 X 8.6 X 48 mm were conducted on an Instron material testing system at room temperature (21°C) and at —196°C. Figure 22.4 shows the stress-strain curves obtained through three-point bending tests of X-SiOx and X-VOx at room temperature and cryogenic... 

Smooth specimens can be stressed by a constant load, by constant strain rate, or by constant deflection, which is the usual procedure. Typical specimens are (a) direct tension specimens, (b) C-ring specimens, (c) U-bend sp>ecimens, (d) bent beam specimens, and special techniques for weldments (see ASTM G 49, Practice for Preparation and Use of Direct Tension Stress-Corrosion Test Specimens ASTM G 38, Practices for Making and Using C-Ring Stress-Corrosion Test Specimen ASTM G 30, Practice for Making and Using U-Bend Stress-Corrosion Test Specimens ASTM G 39, Practice for Prep>aration and Use of Bent-Beam Stress-Corrosion Test Specimens and ASTM G 58, Practice for the Preparation of Stress-Corrosion Test Specimens for Weldments, respectively). 

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