Attracting cracks for arrestment in bone-like composites

Osteonal bones are crack-tolerant due to their repair activity and special tissue structures formed by interstitial material and osteons. Crack-resistant engineering structures may be developed by mimicking bones. In this paper, bone-like composite materials were modeled by using circular inclusions as osteons and their cement lines. A two-inclusion model was investigated to see how crack location and inclusion size and property variations affect the propagation of an initial crack between the inclusions. A four-inclusion model was studied to determine conditions for attracting cracks to inclusions for arrestment. The four-inclusion model was optimized in order to arrest any crack initiated within the interstitial material between the inclusions. The optimized model was verified with the FRANC2D software. The results showed that inclusions with effective elastic moduli smaller than that of the interstitial material always tend to attract cracks. On the contrary, an inclusion with effective modulus greater than that of the interstitial material has a tendency to repel cracks. A crack's propagation direction can be changed by varying inclusions' sizes and elastic properties. At optimal point, any crack initiated within the interstitial material between the four inclusions can be attracted to two inclusions for arrestment. (C) 2004 Elsevier Ltd. All rights reserved.