A series of crack growth tests on an aluminium alloy under cyclic stresses gave the following...

 

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A series of crack growth tests on an aluminium alloy under cyclic stresses gave the following empirical relationship: da = 4x10-"[AK]54 dN where daldN has the unit of m/cycle and AK has the unit of MPa m". The fracture toughness of the aluminium alloy is 35 MPa m' 1/2 1/2 Discs manufactured from the aluminium alloy are used in the rotor assembly of a gas turbine. During assembly of the system a scratch is made on the surface of the disc. The rotation of the turbine blades cause a maximum stress of 350 MPa, perpendicular to the plane of the scratch causing it to open, and the minimum stress can be assumed as zero. The plastic zone correction can be ignored. (i) If the depth of the scratch is 0.1 mm, calculate the number of cycles that the aluminium alloy disc can withstand before failure. (ii) Determine the depth of the scratch that will allow the aluminium alloy disc to undergo atleast 2000 cycles in service. A series of crack growth tests on an aluminium alloy under cyclic stresses gave the following empirical relationship: da = 4x10-"[AK]54 dN where daldN has the unit of m/cycle and AK has the unit of MPa m". The fracture toughness of the aluminium alloy is 35 MPa m' 1/2 1/2 Discs manufactured from the aluminium alloy are used in the rotor assembly of a gas turbine. During assembly of the system a scratch is made on the surface of the disc. The rotation of the turbine blades cause a maximum stress of 350 MPa, perpendicular to the plane of the scratch causing it to open, and the minimum stress can be assumed as zero. The plastic zone correction can be ignored. (i) If the depth of the scratch is 0.1 mm, calculate the number of cycles that the aluminium alloy disc can withstand before failure. (ii) Determine the depth of the scratch that will allow the aluminium alloy disc to undergo atleast 2000 cycles in service. A series of crack growth tests on an aluminium alloy under cyclic stresses gave the following empirical relationship: da = 4x10-"[AK]54 dN where daldN has the unit of m/cycle and AK has the unit of MPa m". The fracture toughness of the aluminium alloy is 35 MPa m' 1/2 1/2 Discs manufactured from the aluminium alloy are used in the rotor assembly of a gas turbine. During assembly of the system a scratch is made on the surface of the disc. The rotation of the turbine blades cause a maximum stress of 350 MPa, perpendicular to the plane of the scratch causing it to open, and the minimum stress can be assumed as zero. The plastic zone correction can be ignored. (i) If the depth of the scratch is 0.1 mm, calculate the number of cycles that the aluminium alloy disc can withstand before failure. (ii) Determine the depth of the scratch that will allow the aluminium alloy disc to undergo atleast 2000 cycles in service. A series of crack growth tests on an aluminium alloy under cyclic stresses gave the following empirical relationship: da = 4x10-"[AK]54 dN where daldN has the unit of m/cycle and AK has the unit of MPa m". The fracture toughness of the aluminium alloy is 35 MPa m' 1/2 1/2 Discs manufactured from the aluminium alloy are used in the rotor assembly of a gas turbine. During assembly of the system a scratch is made on the surface of the disc. The rotation of the turbine blades cause a maximum stress of 350 MPa, perpendicular to the plane of the scratch causing it to open, and the minimum stress can be assumed as zero. The plastic zone correction can be ignored. (i) If the depth of the scratch is 0.1 mm, calculate the number of cycles that the aluminium alloy disc can withstand before failure. (ii) Determine the depth of the scratch that will allow the aluminium alloy disc to undergo atleast 2000 cycles in service.

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Question 1 The answer is 58 x 108 cycles dadNV 4 x 10AK354 dadNV 4 x 10350 x 106354 dadNV 4 x 101... View the full answer