(i) State the steps involved in selection of a proper ball bearing from a manufacturer’s catalogue.
Steps Involved in selection of a proper ball bearing from Manufacture’s Cataloge
Theory
Design a helical compression spring with ground ends. The spring index is 12. Maximum load on the spring is 100N and deflection under maximum load is 15 mm. Allowable shear stress of the material is 100 MPa and modulus of rigidity is 4 MPa. Find wire and
A power screw on a machine has single start square thread with a non rotating bronze nut. Axial force on the screw is 15 kN. Allowable stresses for screw material in compression and shear are 85 MPa and 37 MPa respectively. Allowable bearing pressure for
Draw S-N curve. Explain the concept of endurance limit and its need in design of machine elements
Endurance Limit: It is defined as maximum value of the completely reversed bending stress which a polished standard specimen can withstand without failure, for infinite number of cycles (usually 107 cycles).It is known as endurance or fatigue limit (ϭe). Need of Endurance Limit in Machine Design: Endurance limit is used to describe a property of materials: the amplitude (or range) of cyclic stress that can be applied to the material without causing fatigue failure.
Explain the design procedure of shaft on the basis of torsional rigidity. State the equation with SI units. State two applications of this approach.
State four disadvantages of screwed joints.
Four Disadvantages of screwed joints: 1) Screwed joints are weaker than welded joint 2) Screwed joints weakens( due to holes) the parts that are to be joined. 3) Stress concentration in the threaded portion of screw makes them weak. 4) Locking arrangement is required in case of vibrations
State four important modes of gear failure.
Modes of Gear Failure: ANY 4 modes 1. Bending failure. Every gear tooth acts as a cantilever. If the total repetitive dynamic load acting on the gear tooth is greater than the beam strength of the gear tooth, then the gear tooth will fail in bending, 2. Pitting. It is the surface fatigue failure which occurs due to many repetition of Hertz contactstresses. 3. Scoring. The excessive heat is generated when there is an excessive surface pressure, high speed or supply of lubricant fails. 4. Abrasive wear.
Write the equation with Wahl’s factor, used for design of helical coil spring. State the SI unit of each term in the equation
State four examples of ergonomic considerations in the design of a lathe machine.
Ergonomics consideration in the design of Lathe machine Any 4 1) The controls on lathe should be easily accessible and properly positioned. 2) the control operation should involve minimum motions. 3) Height of lathe should be match with worker for operation 4)Lathe machine should make less noise during operation. 5) force& power capacity required in turning the wheel as per operation or human being can apply normally. 6) should get required accuracy in operation.
Write the design procedure of knuckle joint.
Design of Knuckle joint Failure of rod in tension
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