Mechanical System Design MSD Practical / Orals Exam

Mechanical System Design MSD Oral Exam 

Chapter Name 
Design of Machine Tool Gear Boxes
Statistical Considerations in Design
Design of Belt Conveyor System for Material Handling
Design of Cylinder
Design of Pressure Vessels
Design of IC Engine Components

Unit 1

1) Explain the significance of Geometric Progression Ratio.
In order to compromise between loss of economic cutting speed and compactness of the drive 

2) Compare the different laws of regulation of speeds in the multi-speed gearbox
A gearbox that converts a high-speed input into a number of different speed output it is called a multi-speed gear box. Multi speed gear box has more than two gears and shafts. A multi speed gearbox reduces the speed in different stages.

3) What is structural formula?
Structural formula 
Ans. Z=P1(X1)P2(x2)...Pn(Xn)
P is no. Of steps x is no. Of speed steps between two stages

4) Explain max loss of economic cutting speed.

5) Explain the types of gearboxes.
Three different types of gearboxes: concentric, parallel, and right angle.

Unit 2

1) Give the comparison between Normal distribution and StandardNormal distributioncurves.
A normal distribution is determined by two parameters the mean and the variance. A normal distribution with a mean of 0 and a standard deviation of 1 is called a standard normal distribution.

2) Explain design tolerance and natural tolerance?

Tolerance design” refers to the selection of specifications for individual components using formal optimization. Specifications might relate to the acceptable length of a shaft, for example, or the acceptable resistance of a specific resistor in a printed circuit board.

Natural tolerances are expectations regarding deviations, represented by control limits set at three times the standard deviation above and below the mean. When in place, the limits demonstrate a 99.73% chance that any given result will occur between the given control limits.

3) Define the following

ii) Sample 

The random elements picked from the population selected randomly for observation

III) Random Variable.
A random variable is a variable whose value is unknown or a function that assigns values to each of an experiment's outcomes. A random variable can be either discrete (having specific values) or continuous (any value in a continuous range).

4) Explain the concept of reliability based design.
Reliability-based Design Optimization (RBDO) uses the mean values of the random system parameters as design variables, and optimizes the objective function subject to predefined probabilistic constraints (such as failure probability or reliability index).

5) Explain the following terms used in statistical analysis :
The unit of measure for central value or Central tendency

  1. Variance
  2. Standard deviation
  3. Median

6) What do you mean by statistics?
Statistics is the study of the collection, analysis, interpretation, presentation, and organization of data. There are 2 main Statistical methodologies, Descriptive Statistics and Inferential Statistics.

7) What are the different types of causes for variation.
There are two types of Variance: Common Cause Variation and Special Cause Variation.

8) Due to what the variation in an apparently identical components occurs?
Standard deviation
Unit of measure of dispersion
Or square root of variance

9) What are the different methods of representing frequency distribution?
The following methods are commonly used to depict frequency distributions in graphic form
1. Histogram or Column Diagram 
2. Bar Diagram or Bar Graph 
3. Frequency Polygon 
4. Smoothed Frequency Polygon 
5. Pie Diagram.

10) Explain histogram and frequency polygon.
  • A frequency polygon is a line graph, whereas a histogram is a collection of adjacent rectangles. 
  • A frequency polygon is multi-dimensional, whereas a histogram is a two-dimensional figure. 
  • Several frequency distributions can be plotted on the same axis as a frequency polygon.

11) Explain assignable causes and chance causes.

Also known as “special cause”, an assignable cause is an identifiable, specific cause of variation in a given process or measurement. A cause of variation that is not random and does not occur by chance is “assignable”.

12) Explain factor of safety.
The factor of safety is defined as the ratio of ultimate stress of the component material to the working stress. It denotes the additional strength of the component than the required strength.

13) What is margin of safety?
The margin of safety is the reduction in sales that can occur before the breakeven point of a business is reached. This informs management of the risk of loss to which a business is subjected by changes in sales.

Unit 3

4) Explain the concept of containerization?
Containerization is the packaging together of software code with all it's necessary components like libraries, frameworks, and other dependencies so that they are isolated in their own "container."

8) What are objectives of material handling system?
The main objectives of material handling are as follows: It should be able determine appropriate distance to be covered. Facilitate the reduction in material damage as to improve quality. Reducing overall manufacturing time by designing efficient material movement.

9) Explain classification of material handling equipment.
Material handling equipment usually falls under four main categories: bulk handling material equipment, engineered systems, storage and handling equipment and industrial trucks.

10) What is purpose of hoisting equipment?
A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be manually operated, electrically or pneumatically driven and may use chain, fiber or wire rope as its lifting medium.

11) Tell examples of hoisting equipment.
Hoisting equipment includes jacks, winches, chain hoists, and cranes. Crane is the only single machine which, as a single piece, is capable of providing three- dimensional movement of the weight.

12) What are the different types of conveyors used in material handling purpose.

13) What do you meant by conveyor?
a mechanical apparatus for moving articles or bulk material from place to place (as by an endless moving belt or a chain of receptacles)

14) What are the limitation of conveyors?
Some of the disadvantages are: The normal design of a belt conveyor is opened. If your product needs to be contained, covers and or drip pans can become expensive and cumbersome. If the material is sticky, belt cleaning can be difficult and generally not very successful.

15) Which are the different types of materials handled by conveyors?
The major types of conveyors are:
  • Chute conveyor.
  • Wheel conveyor.
  • Roller conveyor. Gravity roller conveyor. Live (powered) roller conveyor.
  • Chain conveyor.
  • Slat conveyor.
  • Flat belt conveyor.
  • Magnetic belt conveyor.
  • Troughed belt conveyor.

16) Which are the different elements consists in belt conveyor system?

17) What are the requirements for good belt in belt conveyor system?

18) What are the components of conveyor belt?
Following are the three parts of a conveyor: Belt support. Pulley system. Drive unit.

19) Explain carcase in conveyor belt.
Methods of unloading
i.head pulley discharge
ii.both end discharge
iii.tripper discharge
a.fixed tripperl
b.travelling tripper
iv.plow discharge

20) Explain angle of repose and angle of surcharge in connection with belt conveyor.
It is a direct measure of the kinetic friction . The higher the Surcharge Angle, the more material can be stacked on the belt . It is often the maximum incline of the conveyor . The Angle of Surcharge is normally 5° to 15° less than the Angle of Repose .

21) Which factors are affecting on angle of surcharge?
The angle of repose is important for the design of processing, storage, and conveying systems of particulate materials. When the grains are smooth and rounded, the angle of repose is low. For very fine and sticky materials the angle of repose is high.

22) What is the purpose of idlers in belt conveyors?

23) Explain different types of take-up devices.

24) What are the different methods of feeding / loading to flat belt conveyor?

25) What are the different methods of discharge / unloading to flat belt conveyor?

Unit 4
1) Discuss in brief classification of pressure vessels.
Pressure vessels are divided into reaction pressure vessels, heat exchange pressure vessels, separation pressure vessels, and storage pressure vessels according to the principle of action in the production process.

2) What is 'Autofrettage' ?
Autofrettage is a metal fabrication method with a wide range of applications, from the manufacture of gun barrels on battleships and tanks to the manufacture of fuel injection systems for diesel engines. Autofrettage is similar in theory to shot blasting.

3) Discuss importance of 'Autofrettage'.
The Autofrettage is an important procedure for components which are exposed to high and ultra high pressures. Depending on geometry and strength of material, different degrees of wall thickness permanent deformation are calculated.

4) Explain the methods used for prestressing thick cylinders.
A method of prestressing the working surface of pressure chambers or cylinders comprising the steps of first shot peening their working surfaces to form compressive residual stresses, and then applying fluid pressure at a predetermined magnitude to cause tensile stresses in the working surfaces.

5) Discuss the compound cylinders.
The compound cylinder is composed of two layer cylinders: the inner cylinder and the outer autofrettaged cylinder, between which the interlayer pressure fluid

6) Discuss the classification of unfired pressure vessel based on IS 2825 : 1969.

7) Difference between thin and thick cylinders.
Thick wall pressure vessels is determined by the ratio between the mean radius of the vessel and the thickness of the wall. If this ratio is greater than 10, the vessel is considered a thin wall pressure vessel. If the ratio is less than 10, the vessel is considered a thick wall pressure vessel.

8) For which material lame’s equation is used?
Ductile Materials

9) For which material clavarino’sequation is used?

10) For closed ends cylinders, which equation is used?

11) For open ends cylinders, which equation is used?

12) Which different theories of failures are used in design of thick cylinders subjected to internal

13) Under what condition Birnie’s equation?
 • Birnie's equation is applicable to open cylinders made of ductile material. 

14) Explain weld joint efficiency in pressure vessels.
Joint Efficiency refers to the strength of a welded joint with respect to the strength of the base metal. A Joint Efficiency of 1.00 indicates that the weld has the same strength of the base metal, and it is assumed as if it is seamless.

15) What do you meant by pressure vessel?
A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially higher or lower than the ambient pressure. Examples include glassware, autoclaves, compressed gas cylinders, compressors (including refrigeration), vacuum chambers and custom designed laboratory vessels.

16) Explain category A, category B, category C and category D of welded joints.
Ans.Types of welded joints 
Category A 
Longitudinal welded joints within main shell communicating chambers or nozzles
Category B
Circumferential welds within main shell
Category C
Connecting flat heads and flanges to main frame
Category D
Connecting communicating chambers within main frame

17) Differentiate class 1, class2 and class 3 pressure vessels as per IS 2825.

18) Which material are used for unfired pressure vessels?

Materials used for unfired pressure vessel
  • i.cast iron
  • ii. Plain carbon steel
  • iii. Alloy steel 
  • iv. Aluminium alloy
  • v. Copper and copper alloys 
  • vi. Nickel and nickel alloys

19) What are the guidelines for providing corrosion allowance in pressure vessels?
Corrosion allowance describes an extra measurement added to the thickness of the wall. This helps estimate the expected metal loss throughout the lifespan of certain equipment

20) Which design parameters are used for unfired pressure vessels?
The design of a pressure vessel is based on parameters such as pressure, temperature, corrosion, material selection, etc., and the study of such parameters helps in designing of the vessel. A variety of materials is available which are to be selected according to the application

21) What are the reasons for corrosion in pressure vessels?
A pressure vessel can be subject to corrosion and erosion from without, arising from environmental conditions, or from within, due to the fluids used, as well as operating temperatures and pressures. Both inner and outer surfaces of a pressure vessel may need treatment to guard against corrosion and erosion.

22) Tell the components used for the design of unfired pressure vessels.
There are three components in a pressure vessel that are considered to be basic – the shell casing, necessary attachments, and a base. The other components are considered to mainly include the nozzle and the head. The Shell contains the pressure and consists of plates that have been welded together with an axis.

23) Different types of end closures in unfired pressure vessels.
There are four basic types of pressure vessels heads or Dish ends is most widely used in fabrication of Pressure Vessels.
Flat Heads.
Ellipsoidal Heads.
Toripherical Heads or Flange and Dished Heads.
Hemipherical Heads.

24) Explain area method of compensation.
The area compensation method is very simple. The load-bearing metal cross-sectional area that is lost due to the opening is identified. It attempts to compensate for this area loss by providing extra thickness (i.e, nozzle reinforcement) in the affected vicinity of the hole.

25) Purpose of nozzle and openings.
The main functions of a pressure vessel nozzle opening can be any of the following: To allow the content to move into the vessel or away from the vessel to help further processing of the fluid. To allow the insertion of instrument items. To allow for inspection or access to internal parts (Manholes).

26) What are the methods of providing reinforcement?
Reinforcement techniques are operant conditioning methods designed to increase the likelihood of a desired response. There are three types of reinforcement techniques: positive, negative, and extinguishing. Each technique represents reward, punishment, and ignorance.

27) Which types of supports are used for a vertical pressure vessel?
Bracket or lug support

28) Which types of supports are used for horizontal pressure vessels?
Horizontal vessels are usually provided with saddle supports

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