Describe the main applications of Fracture Mechanics and explain how it could be used in each case. An industrial chain drive mechanism has suffered a fractured tooth as shown in Figure Q3(b). The geometry and fractured surface information is as shown. The tooth experiences a bending moment arising from chain tooth forces and this induces a nominal bending stress in the crack location of 100MN/m for each revolution of the chain wheel. Neglecting crack tip plasticity corrections, consider only mode I loading. chain drive tooth profile fractured surface Broding Moment Figure Q3(b) fatigue surface 20 14cm 10mm Based on all the evidence given, is the size of crack when failure occurred as expected? If the source of the cracking is deemed to originate from a 0.3 mm crack- like surface scratch extending across the full breadth of the tooth induced at the time of manufacture, determine whether such a defect would be problematic and estimate the number of cycles to failure. (6) (6) (8)