4. The resistance curve The resistance curve of a brittle material fits the expression: where K, and ß are material parameters. Consider the effects of small cracks in a body designed to carry a fixed stress level o. Assume that the stress intensity factor is given by: (a) Obtain the critical crack size ac for initiation. (b) Determine the relationship between Ko and B to ensure that this critical crack is stable. (c) Discuss the implication of increasing Ko. (d) Discuss the implication of increasing B. (e) Discuss the implication of increasing the design stress

Fig: 1