MECHANICAL ENGINEERING (Diploma Level) Paper—I
Forces: Transmissibility, moments and couples. funicular polygon, lami’s theorem, varigon theorem. Friction: Limiting and dynamical tiiction, coefficient of friction. bodies on inclined planes, simple screw jack. Machines: Basic terms-mechanical advantage, velocity ratio, mechanical efficiency. Lifting machines: System of pulleys-weston differential pulleys. Stress and strain: Volumetric and lateral strains hooke`s law, poisson ratio, modulus of rigidity bulk modulus. Application to bars and composite sections. Beams and trusses: Determinate cases, bow’s notation. Types of supports. Graphical methods: Analytical methods ofjoints and sections. Thin cylinders and spherical shells: Hoop stress. longitudinal stress. Changes in dimensions and volumes ofthin shells subjected to internal pressure.
Theory of Machines and Automobile Technology
Slider crank mechanism: Turning moment in single cylinder engine: Fluctuation of speed and energy; crank effort diagrams. flywheel size. Gear drive: Gear trains; simple, compound, epicyclic and reverted. automobile gear box. Automobile differential. Clutches: Function ofclutch in automobiles. Single plate and multiplate clutches. Friction torque for uniform wear and uniform pressure. Cams: Comcept. classification of different cams and followers. Application to automobile engines, simple cam profiles for uniform velocity. SHl\/I and uniform acceleration balancing. Static and dynamic balancing. balancing of masses rotating in same plane. Basic concept of several masses rotating in different planes, Application to automobile engines. Belt drive.
Derivation of limiting ratios of driveing tensions, centrifugal tension V-belts. Ropes and chains. Dynamometers: Classification, functions, construction and working concepts. Governor: Functions, classification: Watt, porter, hartnell, hartung. Elementary numericals about height. maximum and minimum radil, controlling force etc.
Mechanics of Solids
Mechanical properties of materials: Concept of stress and strain, stress-strain curves of mild steel, aluminium, east iron rubber etc., various modulli determination of stresses and strains in bolts, stepped bars, compound bars and columns obligue plane. Principal stresses, mohr circle. Shear force/bending moments/deflection: analysis of cases of concentrated and uniformly distributed load. Shear force and bending moment’s diagrams: Cantilever, simply supported. overchanging beams.
Strain energy: resilience, derivation of fonrnulae of strain energy for uniform bars in tension, shock load, shear stress. Modulus of resilience. Torsion: solid and hollw circular shafts—polar modulus. weights, power transmitted. Springs: close colled helical springs. Laminated springs. Maximum stress and central defiection, (simple numericals, no proof of formulae). Columns and struts: long and short columns, slenderness ratio. End conditions and equivalent lenghts. Euler and rankine formulae (no derivation).
Materials: Ferrous—iron, steel. alloy steels. Nonferrous metals-aluminium. zinc, copper, tin, lead.
Nonmetallic materials—timber, polymers. Basic knowledge of their production. Structure of materials: Crystalline, amorphous, arrangement of atoms. Crystal structure, imperfections. mechanical properties of common metals and alloys. deformation. Heat treatment: lron-carbon equilibrium diagram, TTT curves; recovery rccrystallisation and grain growth, elementary concepts of hardening, tempering, annealing normalizing and case hardening. Alliy elements: effects of alloying Cr.Co,Si,Mn etc., Tool steels, stainless stccls. heat resisting alloys, spring steel. Nonferrous materials: Duralumin, soldcrs, brass, bronze. gnmetal, inconel. Non—metallic materials: Timber- plywood, hard board, seasoning. Polymers. thcrmoplasts and thermosets. Heat insulating materials. Glass wool, thermocol, rubber.
Electric insulation materials: Bakelite. mica refractory materials; composites.
Design and Estimating
General design considerations for machine parts: Steps in machine design. factor of safety.
Mechanical properties of materials. selection of materials. Machine parts subjected to the following loadings:
(i) Direct and shear loads: Theaded connection, cotter and knucle joints
(ii) Bending moment: Design for railway wagon axle and road vehicle axles. Proof load and proof stress. Semi elliptic laminated springs, maximum stress and deflection, (iii) Twisting moment: Solid and hollow shafts. Design of keys and coupling bolts in rigid fianged coupling. Reveted and welded joints: Types of reveted joints, strength, efficiency, safe load and pitch of revets, lap and butt joints. Common types of welded joints, leg length, throat thickness and size of weld. Simple design for vee, butt, transverse fillet and parallel fillet welded joints. Theories of failure: Maximum principal stress theory, maximum shear stress theory, concept of equivalent bending moment and torque; Rolling elements bearing: Equivalent load, dynamic capacity, life of bearings. Estimation of material requirements: Estimation of weight of simplc machine parts. Review ofthe area/volume oftriangle, hexagon, octagon, cylinder, frustum of cone and pyramid etc. Estimation of time for common operations: Turning, facing, theading. drilling, shaping, chamfering. Simple problems pertaining to above. Estimation of cost: Concept of costing-direct materials. indirect materials, direct labour, indirect labour. overhead expenses. Break-even analysis. Cost estimation of welding: Cost of materials, fabrication, preparation. welding. finishing and overhead expenses.
Plant Layout: General plant location factors. selection of plant site. Product layout, process layout.
Standardization: National and international standards, value of standardization. Standardization techniques and problems. Quality Control: Elements of quality control and objectives. Frequency distribution. X-R charts. P-charts, C·charts and acceptance sampling concept of production. Inspection and its objectives. Types of inspections.
Work Study: Flow process chart, fiow diagrams, work measurment, time study. Time and motion study. Products, planning and control: Sales forecasting and its uses. Planning—products, process, parts, materials. Optimum batch quantity for production and inventory. Routing, dispatching and follow-up activities.
Inventory control: Elements of control procedurers, types of controls. Inventory control system of bin and recorder cycle system. Safety stock concepts. Material handling: Factors in material handling problems. Reduction of cost and time through improved material handling.
Material handling equipment: Lifting, lowering, transporting and combination devices. Industrial safety: Need for safety lega|, humanitarian, economic and social considerations. Safety at work place·unsafe conditions and hazards-electrical hazards, lighting, ventilation, heat control, noise and vibrations, fire and explosion, chemical hazards; hygiene. Brief knowledge of relevant acts like factory act, workman compensation act, lndian boiler act, Indian electricity act, explosive act.