The objective of this work was to experimentally verify the tearing instability theory based on COD-R curve using three point bend specimen geometry of SCM-4 steel. In this investigation the variation of COD-R curve and overall rotational factor for different initial crack ratio was studied also.
COD-R curve was obtained by using double clip gauge arrangement and formula for applied tearing modulus was derived under the assumption of limit load condition.
It was found that specimens with shorter values of initial crack length present higher resistance and overall rotational factor was independent of initial crack length and crack increment.
It was concluded that the tearing theory based on COD-R curve could be applied to predict instability.