QUANTITATIVE RELATIONSHIP BETWEEN YIELD STRESS AND r-VALUE OF Ti SHEET

Based on the experimental data,it was clarified that the plastic strain ratio R-value is notequal to Hill's r-value for Ti sheet.From the non-quadratic orthotropic yield function pro-posed recently by the author,an optimal expression between yield stress and r-value for Tisheet was developed on overall investigation.The suitable value of exponent in the functionseems to be 6—8.Thus,an equation was suggested to estimate strength for the pressure vesselmade of Ti sheet.