Download DBATU B.Tech 2019 Oct-Nov Mech 1st Sem Machine Design I Question Paper

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Subject Name: MACHINE DESIGN-I

Max Marks: 20

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DR. BABASAHEB AMBEDKAR TECHNOLOGICAL UNIVERSITY, LONERE

Mid Semester Examination – Sept./Oct. 2019

Course: B. Tech in MECHANICAL ENGINEERING

Sem: I

Subject Code: BTMEC 503

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Date:-26.9.19 Duration:- 1 Hr.

Instructions to the Students:

1. Assume the suitable data where ever necessary
2. Draw appropriate figures where ever necessary

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1. Standards are obligatory norms (CO1) (1)
2. Ergonomics design is relation between man and machine (CO1) (1)
3. Brittle material shows negligible deformation before fracture (CO1) (1)
4. Factor of safety indicates strength of the material (CO1) (1)
5. Endurance limit is criteria of failure for components subjected to external fluctuating load. (CO1) (1)

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6. Maximum principal stress theory is the most suitable theory for ductile materials (CO4) (1)

Q.2 Solve Any Two of the following.

1. In a Knuckle joint, force acting is 25kN. Material for the pin and the rod is 45C8, Syt=380N/mm². FOS is 2.5. The yield strength in shear 57.7% of Syt. Calculate diameter of rod and Pin. Neglect bending of pin. (CO2 and CO3)
2. An axial pull of 12kN and a transverse shear force 6kN acts on a bolt. The bolt is made of 45C8, Sut=310N/mm². Fos=2.5.Determine diameter of the bolt by using maximum shear stress theory. (CO4)
3. Discuss aesthetic factors in design. (CO1)

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Q.3 Solve Any One of the following.

1. The work cycle of a mechanical components subjected to a completely reversed bending stresses consists of the following three elements, +350N/mm2 for 85% of time, ±500N/mm2 for 3% of life and ±400 for remaining part of the life. The component is made of 50C4 (Sut=660N/mm²), If the endurance limit of the component is 280N/mm². Determine its life (CO5)
2. A plate made up of 40C8, (Sut=580N/mm²) as shown is subjected to completely reversed axial force of 40 kN. The theoretical stress concentration factor at the change in the cross section is 2.27 and notch sensitivity is 0.8. The surface finish factor and the size factor are 0.75 and 0.85 respectively. The load factor is 0.923. The expected reliability is 90%, for which reliability factor if 0.897. If the required factor of safety is 2, determine the plate thickness for infinite life. (CO5)

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