STP844

    Requirements for Flexure Testing of Brittle Materials

    Published: Jan 1984


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    Abstract

    Requirements for accurate bend testing at room temperature of four-point and three-point beams of rectangular cross section are outlined. The so-called simple beam theory assumptions are examined to yield beam geometry ratios that will result in minimum error when utilizing elasticity theory. These errors are referred to as internal error sources, whereas those errors that result from wedging stress, contact stress, load mislocation, beam twisting, friction at beam contact points, contact point tangency shift, and neglect of corner radii or chamfer geometry in stress determination are termed external error sources. Also included are estimates of errors in the determination of the Weibull parameters as a function of sample size. Error tables and formulas, based on the previously mentioned factors, are presented.

    Such analyses and results provide guidance for the accurate determination of flexure strength of brittle materials within the linear elastic regimen.

    Keywords:

    test methods, flexure strength, mechanical properties, brittle materials, mechanics, structural reliability


    Author Information:

    Baratta, FI
    Mechanical engineer, Army Materials and Mechanics Research Center, Watertown, Mass.


    Paper ID: STP35245S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP35245S


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