![]() ![]() ![]() Two displacement transducers, one on each side of the beam, are mounted mid-span to take measurements of beam deflection. A net deflection flex jig surrounds the beam and clamps to the beam at its neutral axis directly over the supports.Loading nose and lower support rollers shall have the ability to rotate on their axes.The span length, or the distance between the two support points, should be three times the specimen depth or 300 mm (12 in), whichever is higher.The 3 rd point loading fixture features two supports underneath the beam.For a 100 by 100 by 350 mm (4 by 4 by 14 in) beam, spacing between the loading noses is 300 mm (12 in).For a 150 by 150 by 500 mm (6 by 6 by 20 in) beam, the spacing between the loading noses is 150 mm (6 in).The load is applied by two loading noses on the top of the beam.Specimen size recommendations per ASTM C1609 are:.Net deflection is the average of two displacement sensors placed on either side of the specimen. The standard also lays out that the test must be conducted in servo control at extremely slow net deflection rates. The objective of ASTM C1609 is to not just find the maximum strength of the concrete but also to determine the remaining strength of the fibers after the initial crack is apparent.įor this reason, the test continues to be conducted beyond the first peak. The sample shall be long enough to account for overhanging on each end of a minimum of 10% of the support span (at least 6.4 mm (1⁄4 in) on each end).Ĭylindrical rollers for ASTM D790 bend testing ASTM C1609 Bend Testing – Fiber Reinforced Concrete BeamsĪSTM C1609 is used to measure the flexural performance of fiber reinforced concrete beams.The loading nose’s maximum radius shall be no greater than four times the specimen depth.For specimens 3.2 mm or higher in depth, the radius of the supports may be up to 1.6 times the specimen depth. If default radii are not used, the minimal radius recommendation radius is 3.2 mm (1⁄8 in).The loading nose and supports’ default radii are 5.0 ± 0.1 mm (0.197 ± 0.004 in).Cylindrical rollers are the recommended loading nose and supports.A ratio bigger than 16:1 may be required for laminated thermosetting materials and materials used for electrical insulation. The recommended support span-to-depth ratio per ASTM D790 is 16 to 1.The rectangular specimen is loaded by a loading nose at the midpoint between the supports (three-point-loading).The standard includes comprehensive specifications on the endorsed bend fixture for this kind of testing, as the following lists: ![]() Note: Dependent upon the industry, terminology may change when using “three-point loading” and “four-point loading.” ASTM D790 Bend Testing – Reinforced and Unreinforced Plastics and Electrical Insulating MaterialsĪSTM D790 is utilized to measure the flexural strength and flexural modulus of reinforced and unreinforced plastics, including materials that are high-modulus composites and electrically insulated. Three-point bend fixtures: A flexural strength testing configuration where a sample is loaded at a location at the midpoint between two support bearingsįour-point bend fixtures: A flexural strength testing configuration where a sample is loaded in a symmetrical way at two areas that are situated one quarter of the overall span, at a distance from the outer two support bearings The two frequent kinds of bend fixtures are three-point and four-point bend fixtures. This article will explore the requisite equipment for typical testing standards as well as available equipment for use in less typical testing applications. Universal testing machines outfitted with bend fixtures are used in calculating flexural strength, flexural modulus, yield point, and more. Whilst it is clear to see why bend testing has to be conducted on inflexible materials like plastics (ASTM D790) and concrete (ASTM C1609), as a matter of fact, bend test applications are often seen in various industries. ![]()
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