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Photoelasto-plastic analysis of notched-bar configuration subjected to bending

The purpose of this work was to determine the 3-D elasto-plastic stress distribution along the line of symmetry for a notched-bar configuration subjected to bending

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Abstract

Knowledge of the three-dimensional stress distribution near a notch for a strain-hardening material in an elasto-plastic state is limited, to say the least. This experimental investigation is concerned with obtaining some insight concerning the three0dimensional elastoplastic stress distributions and the associated plastic-zone sizes. A notched-bar configuration (scaled-up Charpy specimen) subjected to flexure was selected for this purpose. The three-dimensional elasto-plastic stress distributions were determined along the plane of symmetry adjacent to the notch for two levels of applied bending moment.

The experimental-stress-analysis method utilizes the creep and frozen-stress characteristics of an epoxy resin when subjected to a thermal cycle whose maximum temperature is significantly less than the critical temperature of the model material. The resulting frozenstress-strain behavior is characterized by the generation of a nonlinear effective stress-strain curve. This effective stress-strain curve was generated by subjecting uniaxial tensile specimens to constant stress and the appropriate thermal cycle. Also, an effective birefringence-stress curve was obtained from these tensile specimens (calibration). Then the notched-bar configuration was subjected to the thermal cycle and an applied bending moment which would develop a plastic zone (determined by using a distortion-energy-yield criteria). The stress distributions were determined from photomechanical analysis of the slices removed from the model.

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Authors and Affiliations

  1. charge of Photomechanics Group at Lockheed Research Laboratories, Palo Alto, Calif

    Alvin R. Hunter (Research Specialist)

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  1. Alvin R. Hunter
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Hunter, A.R. Photoelasto-plastic analysis of notched-bar configuration subjected to bending. Experimental Mechanics 10, 281–287 (1970). https://doi.org/10.1007/BF02320679

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