6. a. Using a machine element , describe fatigue in engineering materials . Why is fatigue loading more dangerous than normal loading. As a design engineer, how can you prevent failure by fatigue.
d. A building collapsed in a city last month. List all possible reasons that could have caused the failure and how these could have been prevented.

c. What is the effect of extreme temperatures (too low or too high) on the property of material ( yield strength, ductility, toughness, brittleness , fatique strength)

Q : It is desired to maintain the temperature of hospital room at 24 degree centigrade at all the time . The size of the room is 12x12 having 2 ton Air conditioner and 1200 watt heater.

A) discuss proper mechanism so that the temperature should not exceed 24 degree centigrade at any condition ( Hot or cold weather ).

B) suggest and draw a block diagram for temperature control system for hospital room

5 a. A hollow circular cylinder is made of cast iron and has an outside diameter of 120mm and inside diameter of 95mm. The length is 960mm. It is subjected to an axial tensile load of 160kN. Determine the normal stress and extension of the cylinder if the Modulus of elasticity is 230GPa.

b. A hollow bar of rectangular cross section has an external cross section of 30cm by 55cm with a thickness of 10cm. It is subjected to and internal pressure of 2.3MPa, bending force of 8kN acting over a distance of 3m and a torsional load of 35kNm. Determine the maximum tensile and shear stresses. Using a factor of safety of 6, whatis the maximum allowable combined stress in the bar.

The theory of viscoelasticity is used to describe the behaviour of materials in liquid phase.
a. Describe an industrial application where viscoelasticity occurs.
b. Describe any two models of viscoelasticity
c. For each of the models, identify a real life engineering problem where it is applied and describe this.
d. How can the knowledge be used in design applications for the problem you identified
above.
e. What are the challenges in the use of the knowledge for solving practical problems.

A wing designer comes up with two wing designs with different efficiency factors for a highaltitude
reconnaissance aircraft. The aircraft flies in steady, level flight at low subsonic cruise
speeds so that it can obtain better images of the ground underneath. If the weight, engine
thrust, aircraft speed and altitude are fixed, and induced drag is always the same fraction of
the total drag, derive a relationship between wing span and efficiency factor.

A high carbon steel shaft is used in an engine and subjected to different loads. In order to analyse the stress in the shaft, consider a rectangular element within the material. This element is subjected to compressive stress of 135 MPa and shear stress of 166MPa in the vertical direction. The compressive stress in the horizontal direction is 176MPa with a shear stress of 115MPa.

d. What will be the difference in the analysis above if there is an additional torsional load (T) and bending moment (M).
e. Show how you can use any theory of failure to design this shaft.
f. What are the challenges of applying the theories of failure in actual engineering practice and as a design engineer, how would you deal with these challenges.

a. Sketch the state of stress on this element.
b. Determine the maximum and minimum normal and shear stresses and their plane of orientation.
c. If the yield strength of the material is 350MPa, Poison’s ratio is 0.32, and factor of safety is 5, determine the diameter of the shaft to avoid failure.

A machine is out of order for major work. Define controls
exercised in Maintenance Department required for its Maintenance.

A high carbon steel shaft is used in an engine and subjected to different loads. In order to analyse the stress in the shaft, consider a rectangular element within the material. This element is subjected to compressive stress of 135 MPa and shear stress of 166MPa in the vertical direction. The compressive stress in the horizontal direction is 166MPa with a shear stress of 115MPa.
a. Sketch the state of stress on this element.
b. Determine the maximum and minimum normal and shear stresses and their plane of orientation.
c. If the yield strength of the material is 350MPa, Poison’s ratio is 0.32, and factor of safety is 5, determine the diameter of the shaft to avoid failure.

System of external forces acting on a planar rigid body will cause its motion in a certain
manner. Explain in general how Newton’s laws of motion are used to describe this
relationship between external forces and the resulting motion. Draw free-body and inertia-
force diagrams clearly to illustrate this relationship
(5 mark)

For the two-dimensional, incompressible, irrotational flow, examine the uniform flow and the double flow superposition (flow over the roller).

a) Flow function and velocity potential.

b) Velocity field.

c) Stopping points.

d) Roller surface.

e) Surface pressure distribution.

f) Tensile force on the circular cylinder.

g) Lifting force on the circular cylinder.

why self heating is a problem in RTD's and not in thermisters?

A walk –in cooler 3 m by 5 m by 3m High equipped with twelve 0.6 m by 0.6 m triple-glass doors is used for general purpose storage in a drive-in market (heavy usage). The walls are insulated with 50 mm of expanded cut cell polystyrene, and the cooler is to be maintained at 2°C. Compute the cooling load in kilowatts based on a 16-h operating time if the ambient temperature is 25°C.

Describe the major categories of ferrous alloys.

Please find the correct option.(A-B-C-D)

A gas turbine power plant operates on a simple Brayton cycle with a pressure ratio of 8. Air enters the compressor with 37 degrees Celsius and 100 kPa pressure. The highest temperature of the cycle is 900K. The compressor and turbine are isentropic and their efficiency is 90% and 80% respectively. The properties of air will be assumed to be constant as Cv = 0.718 kj/kgK, Cp = 1.005 kj/kgK and R = 0.287 kj/kg, k = 1.4. Since the flow rate of the air entering the cycle is 1000kg / h, what is the net power of the cycle?

A-) 8
B-) 83
C-) 140
D-) 43

Thermodynamics