Measurement of Residual Stresses by the Hole-Drilling Strain Gage Method

Strain-Measurement Instrumentation The residual stress rosettes described previously impose no special instrument requirements. When measurements are to be made in the field, a portable, battery-operated static strain indicator, supplemented by a precision switch-and-balance unit, is ordinarily the most effective and convenient instrumentation. The Vishay Measurements Group Model P-3500 Strain Indicator and SB-10 Switch-and-Balance Unit are ideally suited for this type of application. In the laboratory it may be convenient to use a computerized automatic data system such as the Vishay Measurements Group System 5000 , which will rapidly acquire and record the data in an organized, readily accessible form. A special off-line Windows-based computer program (RESTRESS TM ) is also available to perform and calculate residual stress magnitudes in accordance with ASTM E837. The data base for the program includes values of the coefficients and for blind holes, and covers the full range of recommended hole dimensions applicable to all Micro-Measurements residual stress rosettes.

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