Thursday, April 20, 2017

Mechanical Engineering - Interview Questions






GATE 2017 Mechanical Engineering Syallbus




Section 2: Applied Mechanics and Design

Engineering Mechanics: Free-body diagrams and equilibrium; trusses and frames;
virtual work; kinematics and dynamics of particles and of rigid bodies in plane
motion; impulse and momentum (linear and angular) and energy formulations,
collisions.

Mechanics of Materials: Stress and strain, elastic constants, Poisson's ratio; Mohr’s
circle for plane stress and plane strain; thin cylinders; shear force and bending
moment diagrams; bending and shear stresses; deflection of beams; torsion of
circular shafts; Euler’s theory of columns; energy methods; thermal stresses; strain
gauges and rosettes; testing of materials with universal testing machine; testing of
hardness and impact strength.

Theory of Machines: Displacement, velocity and acceleration analysis of plane
mechanisms; dynamic analysis of linkages; cams; gears and gear trains; flywheels
and governors; balancing of reciprocating and rotating masses; gyroscope.

Vibrations: Free and forced vibration of single degree of freedom systems, effect of
damping; vibration isolation; resonance; critical speeds of shafts.

Machine Design: Design for static and dynamic loading; failure theories; fatigue
strength and the S-N diagram; principles of the design of machine elements such as
bolted, riveted and welded joints; shafts, gears, rolling and sliding contact bearings,
brakes and clutches, springs.

Section 3: Fluid Mechanics and Thermal Sciences

Fluid Mechanics: Fluid properties; fluid statics, manometry, buoyancy, forces on
submerged bodies, stability of floating bodies; control-volume analysis of mass,
momentum and energy; fluid acceleration; differential equations of continuity and
momentum; Bernoulli’s equation; dimensional analysis; viscous flow of
incompressible fluids, boundary layer, elementary turbulent flow, flow through pipes,
head losses in pipes, bends and fittings.

Heat-Transfer: Modes of heat transfer; one dimensional heat conduction, resistance
concept and electrical analogy, heat transfer through fins; unsteady heat
conduction, lumped parameter system, Heisler's charts; thermal boundary layer,
dimensionless parameters in free and forced convective heat transfer, heat transfer
correlations for flow over flat plates and through pipes, effect of turbulence; heat
exchanger performance, LMTD and NTU methods; radiative heat transfer, StefanBoltzmann law, Wien's displacement law, black and grey surfaces, view factors,
radiation network analysis.

Thermodynamics:  Thermodynamic systems and processes; properties of pure
substances, behaviour of ideal and real gases; zeroth and first laws of
thermodynamics, calculation of work and heat in various processes; second law of
thermodynamics; thermodynamic property charts and tables, availability and
irreversibility; thermodynamic relations.

Applications: Power Engineering: Air and gas compressors; vapour and gas power
cycles, concepts of regeneration and reheat. I.C. Engines: Air-standard Otto, Diesel
and dual cycles. Refrigeration and air-conditioning: Vapour and gas refrigeration
and heat pump cycles; properties of moist air, psychrometric chart, basic
psychrometric processes. Turbomachinery: Impulse and reaction principles, velocity
diagrams, Pelton-wheel, Francis and Kaplan turbines.


Section 4: Materials, Manufacturing and Industrial Engineering

Engineering Materials:  Structure and properties of engineering materials, phase
diagrams, heat treatment, stress-strain diagrams for engineering materials.

Casting, Forming and Joining Processes: Different types of castings, design of
patterns, moulds and cores; solidification and cooling; riser and gating design.
Plastic deformation and yield criteria; fundamentals of hot and cold working
processes; load estimation for bulk (forging, rolling, extrusion, drawing) and sheet
(shearing, deep drawing, bending) metal forming processes; principles of powder
metallurgy. Principles of welding, brazing, soldering and adhesive bonding.

Machining and Machine Tool Operations: Mechanics of machining; basic machine
tools; single and multi-point cutting tools, tool geometry and materials, tool life and
wear; economics of machining; principles of non-traditional machining processes;
principles of work holding, design of jigs and fixtures.

Metrology and Inspection: Limits, fits  and tolerances; linear and angular
measurements; comparators; gauge design; interferometry; form and finish
measurement; alignment and testing methods; tolerance analysis in manufacturing
and assembly.

Computer Integrated Manufacturing: Basic concepts of CAD/CAM and their
integration tools.

Production Planning and Control: Forecasting models, aggregate production
planning, scheduling, materials requirement planning.

Inventory Control: Deterministic models; safety stock inventory control systems.

Operations  Research:  Linear programming, simplex method, transportation,
assignment, network flow models, simple queuing models, PERT and CPM.

Interview Questions

Mechanical Engineering Materials


What are common engineering metals?

What are densities of   Iron, Aluminum, Magnesium, Titanium?

What are tensile strengths of Iron, Aluminum, Magnesium, Titanium?



Theory of Machines


What is a kinematic pair?
What is a lower pair? What is a higher pair?
What are various types of kinematic pairs?  Sliding pair, Turning pair, Rolling pair, Spherical pair, Screw or Helical pair

What is a kinematic chain?


When a number of links are connected in space such that the relative motion of any point on a link with respect to any other point on the other link follows a law, the chain is called a kinematic chain.

What is a mechanism?


When any one link in a kinematic chain is fixed, the kinematic chain becomes a mechansim.

What is a machine?


When the kinematic chain is considered as an agent for applying mechanical power, it should be referred to as a machine.

Inversions of Kinematic Chain with Four Lower Pairs (sliding or turning)

The slider crank chain (three turning pairs and one sliding pair)


First inversion: Slider crank
Second inversion: Oscillating cylinder engine, Crank and Slotted Lever mechanism,
Third inversion: Whitworth return motion
Fourth inversion: Hand-pump

The Double slider crank chain (two turning and two sliding pairs)

Pairs of the same kinds are adjacent.

First inversion: Elliptical trammel
Second inversion: Scotch Yoke
Third inversion: Oldham's Coupling

Four Bar Chain or Quadric Cycle Chain - Four turning pairs


1. Oscillatory motion (Crank and Lever Mechanism)
2. Complete rotation of  the crank and the follower - Quick return mechanism
3. Coupled wheels of a locomotive (Double crank)
4. Pantograph (Double lever mechanism)


Design of Machine Elements


Bolts and Screws


Screw pair: The screw thread is a form obtained by cutting a continuous helical groove on the cylindrical surface. The threaded portion engages with a corresponding threaded hole in the nut or machine part, the two elements form what is called a screw pair.

Standard screw thread forms

BSW
B.A.
Metric
Square
Acme
Buttress

Types of threaded fasteners (Bolts and Screws)
1. Through bolts or bolts 2. Tap bolt and cap screws  3. Studs   4. Machine screws

Keys


What is a key? Key joins a shaft to a machine part and the two rotate together. Ex. pulley and a shaft, flywheet and a shaft

What is a cotter?  It is a flat wedge shaped piece of  rectangular cross section  used to connect two shafts.

Shafts


What is a shaft?

Gears


Types: Spur gears, Bevel gears



Springs


What is a spring?
Types of springs: Helical springs, Leaf springs, Spiral springs, Torsion springs, Flat springs, Belleville springs



Strength of Materials


Types of stresses

Tensile, Compressive, Shear

Strain

Tensile, Compressive, Shear, Volumetric

Resiliance


Analysis of Rivet Joint

Lap joint, Butt joint

Design of a Riveted Joint

Diameter of the rivets, Pitch of the rivets, No. of rivets, Thickness of cover plates



Manufacturing Technology


Machining


Types of Machining


Outer surface  - Turning, Milling, Shaping, Planing, Grinding

Inner surface -  Drilling, Boring, Reaming

Screw thread cutting and Gear Cutting

Machine Tools 


Lathe, Milling, Shaping, Planer, Griding Machine, Milling Machine, Boring Machine

Tools - Single point, Multi point   -  Turning, Milling cutters, Shaping tool, Planing tool, Griding wheel, Drills, Reamers, Boring tool, Broach, Tap, Knurling tool

Tools materials:  1. Carbon steels, 2. Medium alloy steels, 3. High speed steels, 4. Cemented carbides 5. Stellites  6. Ceramics  7. Diamond  8. PCBN - Polycrystalline Boron Nitride  9. Abrasives

Coolants  1. Oils  2. Water emulsions  3, Gaseous coolants  4. Dry machining


Operations done on various machine tools


Lathe:  1. Turning,  2. Taper turning, 3. Thread cutting, 4. Chamfering,  5. Knurling  6. Facing  7. Grooving  8. Forming  9. Filing 10. Polishing  11. Reaming  12. Drilling  13. Boring

Milling Machine Operations:  1. Plain milling  2. Side milling, 3. Straddle milling,  4. Gang milling  5. Profile milling,  6.  Form milling,  7. thread milling,  8. Cam milling  9. Helical milling  10. gear cutting  11, Saw milling

Drilling Machine Operations:  1. Drilling  2. Reaming  3. Boring  4. Counter boring  5. Countersinking  6.  Spot facing  7.  Tapping  8.  Grinding  9. Lapping


Updated 23 April 2017,  4 April 2015

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