Solution_tutorial_6_2011_bolts

Solution_tutorial_6_2011_bolts - MECH2100 2011 Solution...

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MECH2100 – 2011 Solution Tutorial 6 – bolts and screw threads 1. L/( π d) = 2/(30 ) = 0.02122 This is more than the coefficient of friction of 0.03. Hence the thread will lock. 2. The proof stress from Table 10.5 is 225 MPa. The 2.5 mm pitch indicates a coarse thread, so the stress area is 192 mm 2 from Table 10.2. Hence the proof load is 43200 N. The share of the applied load taken by a bolt is found from k c = 3000, k b = 1000, giving λ = k b /( k b + k c ) = 0.25. Sharing the applied load equally between bolts (OK if the joint is stiff enough), each bolt load changes by 0.25 * 50/3 = 4.1667 kN. This adds to the preload, giving 39.1667kN in each bolt. This is 91% of the proof load. 3. Tightening torque = 0.2*35000*0.018 (Juvinall, equation 10.12) = 126 Nm 4. The fine thread used here has a larger stress area of 272 mm 2 . Grade 8.8 has a proof stress of 600 MPa. Hence the proof load is 163.2 kN. 75% of this is 122.4 kN. Let the
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This note was uploaded on 11/26/2011 for the course MECH 2100 taught by Professor Billdaniel during the Three '11 term at Queensland.

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Solution_tutorial_6_2011_bolts - MECH2100 2011 Solution...

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