Tensile machine to perform in the method of rule of non-proportional extension strength Rp projects often use Rp0.2 exposed. Usually Rp0.2 reference can be used for the determination of Rp0.01, Rp0.05, and Rp0.1, so we take the example of Rp0.2 paper.
Determination of Rp0.2 using the graphic method, accurate drawing force extension curve ( or stress stretching rate curve ). Our students build the tensile machine automation level is high, can accurately draw the graphic method the critical curve. International rules: linear elastic metal materials with the conventional push E parallel lines, curves of elastic straight for the local reference line; does not have apparently elastic straight segments of metal material for no apparent elastic straight line segment, is recommended to use the hysteresis loop, also outline by using gradual approach method, through pulling machine test reference size : GB/T 228-2002.
The implementation of hysteresis loop to draw the hysteresis loop, emphasized the new scale beyond the expected rule of non-proportional extension strength after descending force, but the practice operation selected expected value to and practice of Rp0.2 on, often resulting in two environmental position coherence.
Unloading point below 1 Rp0.2 and practice ahead of unloading, Rally machine software on the hysteresis loop endpoint connection in parallel lines at the left, with plenty of estimated values of stress, elongation, tensile machine not feasible in. .
2 remove points beyond the practice of Rp0.2, connect in parallel lines is enough, hysteresis loop endpoint connection of parallel lines and unloading force force extension curve in front. This can be used to perform unloading point for arbitration, but too late. So, in a tensile tester must ensure that the connection is located parallel to the line of adequacy, i.e. to control unloading point control header. For more tensile machine to perform diffusion our way please.
