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Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
What are the Main parameters that affect the injection molding process?
Following parameters affect injection moulding process.
1) nature of material (type of plastic)
2) rate of injection
3) size of the component being moulded
4) efficiency of machine
5) type of cooling method adopted
6) curing time in the mould
Use of draft tube in reaction turbine?
1. To reduce velocity/ kinetic energy of water making exit thereby converting kinetic energy to pressure head allowing turbine to be installed above tail pool level.
2. To create negative suction head.
3. Provide added head.
How will burning be affected if nitrogen is not in the air to act as a dilute for oxygen?
Burning will be more agressive and faster. Also self-ignition occurs at a lower temperatures when there is more O2 available.
Where would a Full bore gate valve be used?
Generally speaking, gate valves in larger sizes are full bore unless you order a reduced port. You would always use a full bore gate valve for hot tapping purposes. or you would use a full bore gate vale for runinig a pig in pipeline.
How do you calculate the pitch of a spiral spring?
You can tell if a spiral spring pitch is normal by this equation; 0.2*D < p < 0.4*D. However, you can calculate a spiral spring pitch by l = πDn, A = πd2 /4.
What are the most difficult subjects in mechanical engineering?
im doing my first year in mechanical engineering technology, and the hardest course so far are dynamics, statics and stress analysis.
What is the mechanical engineering syllabus for isro exam?
1. ENGINEERING MATHEMATICS
Linear Algebra: Algebra of matrices, system of linear equations, eigenvalues and eigenvectors.
Calculus: Taylor Series, Fourier Series, partial derivatives, total derivatives, definite and improper integrals, multiple integrals.
Vector Calculus: Gradient, divergence and curl, line and surface integrals, Green, Gauss and Stokes' theorems.
Differential Equations: Linear ODE's, first order non-linear ODE's, initial and boundary value problems, Laplace transform, PDE's-Laplace, wave and diffusion equations.
Numerical Methods: Solution of system of linear equations, interpolation, numerical integration, Newton-Raphson method, Runge-Kutta method.
Probability & Statistics: Gaussian, Weibul distribution and their properties, method of least squares, regression analysis, analysis of variance.
2. APPLIED MECHANICS AND DESIGN
Engineering Mechanics: Equivalent force systems, free-body concepts, equations of equilibrium, trusses and frames, virtual work and minimum potential energy. Kinematics and dynamics of particles and rigid bodies, impulse and momentum (linear and angular), energy methods, central force motion.
Strength of Materials: Stress and strain, stress-strain relationship and elastic constants, Mohr's circle for plane stress and plane strain, shear force and bending moment diagrams, bending and shear stresses, deflection of beams torsion of circular shafts, thin and thick cylinders, Euler's theory of columns, strain energy methods, thermal stresses.
Theory of Machines: Displacement, velocity and acceleration, analysis of plane mechanisms, dynamic analysis of slider-crank mechanism, planar cams and followers, gear tooth profiles, kinematics and design of gears, governors and flywheels, balancing of reciprocating and rotating masses.Vibrations: Free and forced vibration of single degree freedom systems, effect of damping, vibration isolation, resonance, critical speed of rotors.
Design of Machine Elements: Design for static and dynamic loading, failure theories, fatigue strength; design of bolted, riveted and welded joints; design of shafts and keys; design of spur gears, rolling and sliding contact bearings; brakes and clutches; belt, ropes and chain drives.
3. FLUID MECHANICS AND THERMAL SCIENCES
Fluid Mechanics: Fluid properties, fluid statics, manometry, buoyancy; Control-volume analysis of mass, momentum and energy, fluid acceleration; Differential equation of continuity and momentum; Bernoulli's equation; Viscous flow of incompressible fluids; Boundary layer, Elementary turbulent flow; Flow through pipes, head losses in pipes, bends etc.
Heat-Transfer: Modes of heat transfer; One dimensional heat conduction, resistance concept, electrical analogy, unsteady heat conduction, fins; Dimensionless parameters in free and forced convective heat transfer, Various correlations for heat transfer in flow over flat plates and through pipes; Thermal boundary layer; effect of turbulence; Radiative heat transfer, black and grey surfaces, shape factors, network analysis; Heat exchanger performance, LMTD and NTU methods.
Thermodynamics: Zeroth, First and Second laws of thermodynamics; Thermodynamic system and processes; Irreversibility and availability; Behaviour of ideal and real gases, Properties of pure substances, calculation of work and heat in ideal processes; Analysis of thermodynamic cycles related to energy conversion; Carnot, Rankine, Otto, Diesel, Brayton and Vapour compression cycles.
Power Plant Engineering: Steam generators; Steam power cycles; Steam turbines; impulse and reaction principles, velocity diagrams, pressure and velocity compounding; Reheating and reheat factor; Condensers and feed heaters.I.C. Engines: Requirements and suitability of fuels in IC engines, fuel ratings, fuel-air mixture requirements; Normal combustion in SI and CI engines; Engine performance calculations.
Refrigeration and air-conditioning: Refrigerant compressors, expansion devices, condensers and evaporators; Properties of moist air, psychrometric chart, basic psychometric processes.
Turbomachinery: Components of gas turbines; Compression processes, Centrifugal and Axial flow compressors; Axial flow turbines, elementary theory; Hydraulic turbines; Euler-Turbine equation; Specific speed, Pelton-wheel, Francis and Kaplan turbines; Centrifugal pumps.
4. MANUFACTURING AND INDUSTRIAL ENGINEERING
Engineering Materials: Structure and properties of engineering materials and their applications, heat treatment.
Metal Casting: Casting processes (expendable and non-expendable) -pattern, moulds and cores, Heating and pouring, Solidification and cooling, Gating Design, Design considerations, defects.
Forming Processes: Stress-strain diagrams for ductile and brittle material, Plastic deformation and yield criteria, Fundamentals of hot and cold working processes, Bulk metal forming processes (forging, rolling extrusion, drawing), Sheet metal working processes (punching, blanking, bending, deep drawing, coining, spinning, Load estimation using homogeneous deformation methods, Defects). Processing of Powder metals- Atomization, compaction, sintering, secondary and finishing operations. Forming and shaping of Plastics- Extrusion, Injection Molding.
Joining Processes: Physics of welding, Fusion and non-fusion welding processes, brazing and soldering, Adhesive bonding, Design considerations in welding, Weld quality defects.Machining and Machine Tool
Operations: Mechanics of machining, Single and multi-point cutting tools, Tool geometry and materials, Tool life and wear, cutting fluids, Machinability, Economics of machining, non-traditional machining processes.
Metrology and Inspection: Limits, fits and tolerances, linear and angular measurements, comparators, gauge design, interferometry, Form and finish measurement, measurement of screw threads, Alignment and testing methods.
Tool Engineering: Principles of work holding, Design of jigs and fixtures. Computer Integrated Manufacturing: Basic concepts of CAD, CAM and their integration tools.
Manufacturing Analysis: Part-print analysis, tolerance analysis in manufacturing and assembly, time and cost analysis.
Work-Study: Method study, work measurement time study, work sampling, job evaluation, merit rating.
Production Planning and Control: Forecasting models, aggregate production planning, master scheduling, materials requirements planning.
Inventory Control: Deterministic and probabilistic models, safety stock inventory control systems.
Operations Research: Linear programming, simplex and duplex method, transportation, assignment, network flow models, simple queuing models, PERT and CPM.
SK-5 is the Japanese designation for high carbon steel. It isequivalentto SAE/AISI 1080.
10xx meaning "Non-resulfurized carbon steel" and xx80 meaning 0.8% carbon content.
Which is more accurate-true strain or engineering strain and why?
Short answer:
strain engineering = change in L / original L
true strain = ln(1+strain engineering)
Engineering strain is the change in length divided by the original length, so that a 1 inch part strained 50% or .5 in/in would become 1.5 in or if strained -50% or -.5 in/in would become .5 inches. But these two strains are not the same amount of deformation since as a material is stretched further the change in length is distributed over a longer length for positive values and over a smaller length for larger values. Consider progressing from the now 1.5 in. (50%) strained part and continuing to 100% and the .5 in. (-50%) strained part and continuing to -100%. The next change in length is distributed over 1.5 in. and .5 inches respectively despite this the equation considers this change relative to the same original length of 1 inch. True strain is the change in length divided by the instantaneous length integrated from the original length to the instantaneous length. This resolves to the equation above.
Engineering Stress is more of an approximation. As stress levels increase, the actual cross sectional area of the object will change due to the force (think of a rubber band getting thinner as it gets stretched out).
Since stress is force divided by area the stress changes as a product of two variables. If you think of it that way, you are thinking of true stress.
Engineering stress holds the cross sectional area constant at its original value.
So if you look at a stress strain diagram, engineering stress levels off at the ultimate strength but true stress continues to climb because it is being divided by a smaller and smaller number as the object is stretched to the point of failure.
What is HP and LP turbine expansion?
HP Turbine is High Performance Turbine
LP Turbine is Low Performance Turbine
What are the operations carried out on lathe?
The main operations on a lathe are
-turning( reducing diameter)
-facing( reducing length)
-tapering( making a conical shape)
-knurling( making a diamond shaped pattern for easy grip)
-grooving( making a symmetrical indentation)
-parting( removing a section)
-eccentric turning( turning about a point other than axis)
-chamfering( creating a radially symmetrical chamfer)
others include boring, drilling etc.
What is the backplate in nano ic engine?
The backplate is simple turning with only some aspects of work holding posing any problems.
What is the difference between a stress strain curve and a load displacement curve?
a stress strain curve and a load displacement curve is pretty much the same thing, given the data is from the same specimen.
its just the stress (force/area) is divided by a constant area and the strain (change in length/original length) is divided by a constant original length.
therefore your curve would pretty much look the same as dividing by a constant will not change your graph.
hope this explains your question
Is defined as ratio of uniform stress to volume strain?
is defined as ratio of uniform stress to volume strain
Why fracture strength is always greater than yield strength?
The material has to stretch (strain) first before it breaks. For ductile materials, when stretch reaches a certain point it permanently deforms (yield) and continues to carry load until it then breaks as load increases.
For brittle materials like glass which do not permanently deform thay simply break without yield.
What is Young's modulus and poisons ratio of a liquid?
Liquids are not defined by elastic modulus, but rather by bulk modulus, which for water is about 2200 MPa (320,000 psi). It is nearly incompressible, with a Poisson ratio close to, but not quite,0.5
What is the difference between level switch and float valve?
The operation is similar but what they control are two very different things. A level switch, just like the word switch implies, either completes or breaks an electrical circuit when a certain condition is reached. This is similar to the mercury switch in most thermostats. When the ambient temperature reaches a certain point, the bimetal spring of the switch tilts one way and the mercury contained inside the glass tube moves toward one end or the other completing the appropriate electrical circuit to trigger the HVAC system to activate. When another point is reached, the mercury switch tips the other way and breaks the connection because the mercury is not at the opposite end of that tube.
As for a float valve, it functions similarly but rather than making or breaking an electrical connection, it turns on or shuts off a valve that controls the flow of some substance. An example of this is the float valve that controls the filling of the water tank on the back of a toilet. When you hit the switch to flush the toilet, the flapper valve opens and stays open due to the pressure to keep it aloft by the water rushing by it to go out the hole that it usually seals. Once the water has decreased to a certain level at which there is not enough water to keep the flap up, it flops down and seals the breach. At this point, the float inside the tank is at its lowest point, so the water inlet from your plumbing is allowing the water to flow at its maximum rate. As the water level in the take rises, the float also rises which slowly closes the valve until such time the float is at its maximum level and completely shuts off the flow of water.
I hope this helps. If you have any other questions, feel free to drop me a line.
Nozzle clearance how to steam turbine?
Steam turbine nozzle clearance is the total energy content available in steam. This is through a valve.
How do you interpret workpiece reference points and system of tolerancing?
Reference points: Think about how the part will be made, and how it will be inspected. Usually something will make sense. Try to keep common references between drawing views, and if possible try to base everything from points, planes, or edges that appear in multiple views.
Tolerances: Consider how the part will be made- what minimum tolerances can be held on the intended equipment and processes? What is the maximum tolerance on the individual parts that will allow the assembly to fit together and function properly? The right answers lie between those extremes.
The evolution of building techniques:apex
The ultimate strength of annealed SS304 is 80,000 psi (550 MPa). Its yield strength is 30,000 psi, and its shears strength is 80000/(SQRT(3)) = 46000 psi. If it is cold worked, as for bolts, its yield and ultimate and shear strength will increase.
Far more driving surface contact and easier gear selection.
Discrimination is when someone is treated differently
