NEW FORMULA OF EXPERIMENTAL STRESS INTENSITY FACTOR EVALUATION BY CAUSTICS

摘要

A study of the experimental evaluation of the stress intensity factor K_I was undertaken by the method of caustics. A new formula of experimental calculation stress intensity factor was proposed depended to the area of the caustic. A series of experiments were performed in single edge-cracked specimens made of Lexan (PCBA). It was found that the values of the stress intensity factor K_I, which were based on the diameters of the caustics, were varied with the load, the crack length and the caustic shape because the caustic becomes oval in higher loads or higher crack length. This means that the stress intensity values, which are calculated by the two diameters of the caustics (D_t, D_l), are significantly differed. The accurate stress intensity factor K_I can be experimentally evaluated by the area of the formed caustic, In the present work a new formula for the calculation of the stress intensity factor was established.