Machine Component and Design (ME-602) - Important Questions

Explain fluctuating stresses and Goodman and Modified Goodman diagrams with neat sketches

Discuss design considerations for fatigue loading in machine elements.

Discuss Soderberg and Gerber fatigue failure criteria with neat diagrams.

A component machined from a plate made of steel 45C8 ($S_1 = 630\ \mathrm{N/mm^2}$) is shown in Fig. It is subjected to a completely reversed axial force of 50 kN. The expected reliability is 90% and the factor of safety is 2. The size factor is 0.85. Determine the plate thickness $t$ for infinite life, if the notch sensitivity factor is 0.8.

Determine minimum ultimate strength for fluctuating flexural stress using Modified Goodman and Soderberg relations.

Determine diameter of ductile circular rod under fluctuating axial load with stress concentration using fatigue design with factor of safety.

Describe the stress concentration phenomenon in tension, and provide examples.

Explain the S-N Curve and its importance in predicting material fatigue behaviour.

What are the primary causes of stress concentration in materials?

Write short notes on Soderberg equation and applications, shaft couplings, square vs V-threads, and self-locking screw efficiency.

What is meant by stress concentration and how is it considered for a component under dynamic loading?

Determine required diameter of circular rod under combined fluctuating bending moment and fluctuating axial load using fatigue failure criterion with factor of safety.

Explain the design procedure for shafts subjected to combined bending and torsion, including equivalent bending moment and equivalent twisting moment and when they are used.

Determine the required diameter of a solid shaft transmitting given power at given speed with a given bending moment using maximum shear stress theory.

Explain the design of shafts subjected to axial load and dynamic loading.

Find the required length of a parallel key for a shaft transmitting maximum permissible torque using maximum shear stress theory and factor of safety.

Classify keys used for shaft-hub connections.

Discuss the forces acting on a key.

State the difference between rigid and flexible couplings.

Why a hollow shaft has greater strength and stiffness than a solid shaft of equal weight?

Explain fatigue loading in springs and discuss spring failure.

For a close-coiled helical spring with given wire diameter, mean coil diameter, active coils and axial load, determine maximum shear stress and deflection.

Compare helical, leaf, and torsion springs with suitable examples.

For given load, spring rate and maximum deflection, calculate required number of active coils, solid length and wire diameter.

Explain why extension springs are in considerably less use than compression springs.

Design a helical compression spring for given load, deflection, and material limits to find wire diameter, mean coil diameter, number of coils, free length and pitch.

Explain overhauling of screws and the self-locking property of threads and where it is necessary.

Distinguish between close-coiled and open-coiled helical springs.

Explain the friction materials used in brakes and clutches and their properties.

Explain the design/construction of single plate and multi-plate clutches.

Determine the tight-side and slack-side tensions in a simple band brake given drum size, speed, power, friction coefficient and angle of contact.

Numerical calculation of total force on a clutch disc under given pressure distribution using uniform pressure theory.

Explain how the coefficient of friction affects the performance of a rope, band, or block brake system.

Compare and contrast the advantages and disadvantages of rope, band, and block brakes.

Design a plate clutch using uniform wear theory to determine outer and inner diameters of friction surface and required axial/spring thrust for given power/torque, speed, friction coefficient and pressure limit.

Explain uniform wear theory and uniform pressure theory for clutches and give the expression for mean radius in both cases.

Define a self-energizing brake and state the condition for self-locking.

Determine the effort required at the brake lever in a band-and-block brake given number and angle of blocks, lever dimensions, braking torque, drum diameter and friction coefficient.

Explain the design procedure of journal bearings.

Compare journal bearings and rolling contact bearings with suitable examples.

Determine the required dynamic load capacity for a bearing under combined radial and axial load for given speed, life and 90% reliability.

A deep groove ball bearing of basic design no. SKF 6312 has a dynamic load capacity of 81900 N. If this bearing is expected to carry a pure radial load of 37800 N, find the loading ratio and estimate the nominal life of the bearing in millions of revolutions. If the rotational speed of the bearing is 500 rpm, find the bearing life in number of operating hours. Find the reduction in service life when the radial load is increased by 10000 N.

Write a short note explaining the dynamic load capacity of a rolling bearing.

List the important physical characteristics of a good bearing material. And also explain what is bearing characteristic number?

A footstep bearing supports a shaft of $150\, \text{mm}$ diameter which is counter bored at the end with a hole diameter of $50\, \text{mm}$. If the bearing pressure is limited to $0.8\, \text{N/mm}^2$ and the speed is $100\, \text{r.p.m.}$ Find:

What are rolling contact bearings, their advantages over sliding contact bearings, and factors affecting bearing life?

Calculate the catalogue (90% reliability) dynamic load capacity for a bearing required to give a specified life at a higher reliability.

How are bearings classified?

What is a journal bearing? List applications of journal bearings.

Write short notes on any two:

List some factors that influence machine design.

What is 'Adaptive design and Optimum design'?

What is interchangeable manufacturing?

What are unilateral and bilateral tolerances?

Differentiate between Hardness and Toughness of materials.

Determine the force required to punch a hole of 20 mm diameter in a 5 mm thick plate with ultimate shear strength of 250 MPa.