As a cracked plate with a central crack is loaded, the crack length begins to increase...

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As a cracked plate with a central crack is loaded, the crack length begins to increase when the load of 92,500 N is reached, and the crack continues to lengthen under a constant load. When the crack starts to run, the displacement equals 3.2 mm. The final displacement reached in the test is 3.7 mm. The crack area during the test increases by 120 mm. The plate is made of a material with the Young's modulus of 60.4 GPa and oy 410 MPa. (a) Calculate the external work done during the crack propagation. (b) Calculate material toughness R. (c) Estimate by calculation the initial crack length if the plate thickness is equal to 1 mm and the plate width (in the direction normal to the load direction) is 180 mm. (d) Estimate by calculation if plane stress or plane strain conditions at crack tips were produced in the test. As a cracked plate with a central crack is loaded, the crack length begins to increase when the load of 92,500 N is reached, and the crack continues to lengthen under a constant load. When the crack starts to run, the displacement equals 3.2 mm. The final displacement reached in the test is 3.7 mm. The crack area during the test increases by 120 mm. The plate is made of a material with the Young's modulus of 60.4 GPa and oy 410 MPa. (a) Calculate the external work done during the crack propagation. (b) Calculate material toughness R. (c) Estimate by calculation the initial crack length if the plate thickness is equal to 1 mm and the plate width (in the direction normal to the load direction) is 180 mm. (d) Estimate by calculation if plane stress or plane strain conditions at crack tips were produced in the test.