6111mech Structural Integrity Question B 2 The Performance And Structural Integrity Of A Thin Rotating Disc With A Centr 1 (113.97 KiB) Viewed 46 times
6111mech Structural Integrity Question B 2 The Performance And Structural Integrity Of A Thin Rotating Disc With A Centr 2 (110.92 KiB) Viewed 46 times
6111MECH Structural Integrity Question B.2 The performance and structural integrity of a thin rotating disc with a central hole is being investigated. The focus of the investigation is the determination of key stress values and limiting speeds for the disc so as to mitigate against yield and plastic collapse. The disc is in development for use in a gas turbine that is to be employed for power generation. The inner and outer radii of the disc are a = 150 mm and b = 300 mm respectively, the disc material having values of Poissons ratio v = 0.3, density p = 7700 kg/m and yield stress o, = 450 MPa. Equations B2a describe the hoop and radial stress distributions generated in a thin disc due to its rotation. For the disc described: a) determine the limiting rotational speed so as to mitigate against yield in the disc using the maximum shear stress failure criteria (Tresca). [14 marks] B on = A +2-(1+30) ρω?v2 8 egns.B2a ρω?γ2 B Or = A- r2 (3 + v) 8 b) without calculation, sketch the hoop and radial stress distributions set up due to rotation. [3 marks] c) If the rotational speed of the disc were to increase beyond the limiting rotational speed for initial yield: i) describe the development of the plastic zone in the disc up to the point of plastic collapse. [2 marks] [3 marks) ii) calculate the collapse speed of the disc using equation B2b. iii) Describe a manufacturing process that can increase the limiting rotational speed of the disc under consideration. [3 marks] Wp = D. 30yb-a р b3 - a3 ... egns.B2b
Question B.2 The performance and structural integrity of a thin rotating disc with a central hole is being investigated. The focus of the investigation is the determination of key stress values and limiting speeds for the disc so as to mitigate against yield and plastic collapse. The disc is in development for use in a gas turbine that is to be employed for power generation. The inner and outer radii of the disc are a = 150 mm and b = 300 mm respectively, the disc material having values of Poissons ratio v = 0.3, density p = 7700 kg/m’and yield stress Oy = 450 MPa. Equations B2a describe the hoop and radial stress distributions generated in a thin disc due to its rotation. For the disc described: a) determine the limiting rotational speed so as to mitigate against yield in the disc using the maximum shear stress failure criteria (Tresca). [14 marks] B on = A +52 - (1+30) pw²72 8 ... eqns.B2a B ρω?v2 Or = A - - (3 + v) r2 8 b) without calculation, sketch the hoop and radial stress distributions set up due to rotation. [3 marks] c) If the rotational speed of the disc were to increase beyond the limiting rotational speed for initial yield: i) describe the development of the plastic zone in the disc up to the point of plastic collapse. [2 marks] [3 marks] ii) calculate the collapse speed of the disc using equation B2b. iii) Describe a manufacturing process that can increase the limiting rotational speed of the disc under consideration. [3 marks] Wp 30y| b-a b3 - a3 ... egns.B2b
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