The Mechanicals

Hydraulic & Fluid Mechanics

2020-04-02T13:17:00.002+05:30

Hydraulic & Fluid Mechanics

Density/Mass density: mass/unit volume at standard temp and pressure.

rho =M/V

unit: kg /me

Weight density/specific weight: weight /unit volume at standard temperature and pressure.

w=rho x g

unit : N/me

Specific volume: volume/unit mass of liquid

v=V/m

unit : m3/ kg

Specific gravity: it is defined as specific weight of liquid to specific weight of pure water at 4 degree C

it has no unit

Viscosity: it offers resistance to movement of one layer of liquid to another layer

Compressibility: properly change in volume to change in pressure.

it is reciprocal of bulk modulus of elasticity.

Surface tension: property of liquid which enables to resist tensile stress denoted by sigmaunit : N/m

Capalary: phenomena of rise /fall of surface in small tube held in liquid relatives.

Pressure of liquid: When liquid contained in vessel it exerts at all points on side & bottom of vessel

force per unit volume area called intensity by pressure

unit: N/m2

Pascal law : intensity of pressure at any point in liquid at rest is same in all directions

Hydraulic & Fluid Mechanics

Measurement of pressure:

simple pizometer &u tube nanometer
differential nanometer

Menometer used to measure

High pressure of liquid
vacume pressure
pressure in pipe

Archimedes principles: when body is immersed wholly or partially in liquid it is lifted up by force equal to weight of liquid displace by body

Hydraulic & Fluid Mechanics

Tendancy of liquid to uplift an immersed body beacause of upward thrust of liquid is known as buoyancy.

Point where buoyancy force supposed that is known as centre of buoyancy.

bouyancy of force is more= float

bouyancy of force is less =sink down

Meta centre : is a point about which a floating body start oscillating when given smaller angular displacement .

Meta centric height : distance between centre gravity of floating body and metacentre

Uniform flow: all section same velocity

Non uniform flow: different sections have different velocity

stream line : each point have define path and these path does not cross each other.

Bernaulli 's Equation
Z1+(v1/2g)+(p1/W) = Z2+(v2/2g)+(p2/W)

Assumption

fluid is non viscous
fluid is homogeneous and incomressible
the flow is continuous steady and along streamline
velocity flow is uniform over section

Pitot tube measures velocity of flow

very small dia. is ven contracta

spill way ofe wear is used

1poise = 0.1 N-s/m2

1stroke = 1 cm2/s

Hydraulic & Fluid Mechanics

law of viscosity

fluid with no viscosity is ideal fluid
fluid with viscosity is real fluid
viscosity does not change rate of deformation is newtonian fluid
viscosity change with deformation is non newtonian fluid

raynold 's No. less than 2000 is laminar flow

raynold 's No. is greater than 2800 is turbulent flow

Important point of Strength of material

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Important point of Strength of material

Stress : P/A =N/mm2
Strain : Change in length / original length = No unit
Hook's law = good for elastic limit
Modulus of elasticity = linear stress/linear strain

Poison ratio : lateral strain / linear strain (Max. = 0.5)
E = 210 kN/mm2
Strain roseter = used to measure liner strain.
Max. stress at smaller end in tapper bar
bolt pass through pipe both are tightly fitted with nut and washer so bolt in tension tube in compression
bar cooled at -5 degree c it develop tensile stress.
Energy stored in body = strain energy
Total strain energy stored in body = Resilience
Max. strain energy stored in body = Proof resilience
Proof resilience / Unit volume = Modulus of resilience
Strain energy suddenly loaded = 4 x Gradually loaded
Contraflex point = bending moment change sign (overhanging beam)(simply supported beam)
Shear force = 0, Bending moment = max
Bending moment at fix end = max
In pure bending = bending is constant, shear is o

Important point of Strength of material

Elastic strength

if depth double =elastic strength four times
if width double = elastic limit double
if length double = elastic strength 1/4th

Natural axis shear force = 0
Flinched beam is used to equal strength and compression.
Torsional rigidity - " Torque required to produce twist one redian /unit length"

T/theta

Torsional -" closely coil helical spring is subjected to axial "
stiffness of spring = cd4/8D3n
Spring index = Mean dia/ wire dia
Closely coil spring

Wire dia is double = stiffness is 1/6th
No. of turrns is double = stiffness is 1/2
Spring cut in to haft = stiffness is double

Rivets

Rivets are made from ductile material.
Size of hole is grater , 25mm hole = 23 mm rivet
Used for permanent fastener
Generally specified by shank diameter
Shank dia. is minor dia of thread
Center of rivet to nearest edge is margin
Caulking is made for riveted make leak proof.

Unwin formula = 6 x root "t"
Slenderness ratio = Length of column/ Least radius of gyration

Slenderness ratio <80 , Short column
Slenderness ratio <=100 , Long column strength of material

Dam created with cement Concentrate is meson dam.
Hook 's law = good for elastic limit

Important point of Strength of material

Strength of Material

2020-03-30T19:31:00.001+05:30

Strength of Material

Mechanical Properties

Hardness ;Resist the penetration (impact load)
Strength : Ability of material withstand of material without failure.
Elasticity : It regain the original shape after removing load
Plasticity : Permanent deformation after removing load.
Mali ability : Converts to thin sheet without rupture
Ductility : Draw in to thin wire.
Brittleness : No deformation takes place & rupture (lake of ductility ) (cast iron)
Toughness : absorb energy & plastic deformation without rupture.
Fatigue: by repeatedly applied load program me and localized structure damage that occur.
Creep : tendency of solid material to move slowly deform permanently under mechanical stress.

Stress : Load applied on particular area.

it is tensor quantity
unit : N/mm2

Strain : Change in length to original length when force applied on body.

it has no unit.

Strength of Material

Tensile : when body is subjected to equal and opposite pull.
Compressive : when body is subjected to equal and opposite push.
Thermal stress : stress due to change in temperature.
Linear strain : deformation of bar per unit length in direction of force.
Lateral strain : Direct stress dis accomplished strain in its own direction & opposite kind of strain in every direction at right angle is known.
Poison 's ration = Lateral strain / Linear strain

it has no unit
max poison ratio = 0.5 (rubber)

Bulk modulus: Body subjected to 3 mutually perpendicular stress of equal intensity
E = 9KC /(3K+C)

Principle stress & strain:

3 planes are mutually perpendicular to each other
Carries direct stress only
No shear stress
3 direct stress (Max, min, intermediate)

Mohr circle: Graphical method to find Normal tangential resultant stress.

Resilience: Strain energy stored in body due to external loading with in the elastic limit.

Bending Assumption :

Material is homogeneous.
obey hook's law.
Transverse section plane before and after bending.
Each layer is free to explained.
Value of young s modulus is same in tension and compression.

Strength of Material

Bending equation:
(M/I)=(SIGMA /Y)=(E/R),
M= Bending Moment
I = Moment of inertia
Y = Distance from center
E = Young 's modulus
R = radius of curvature

Shear stress in shaft
(Tou/R) = (T/J) = (C x thita )/l
Tou = Shear stress
R = Radius of shaft
T = torque
J = polar moment
C = Rigidity
thita = angle of twist
l = length of shaft

Stiffness of spring : load required to produce unit deflection in spring is called stiffness of spring.
vipul baria

Important points of Engineering Mechanics

2020-03-29T18:06:00.001+05:30

Important points of Engineering Mechanics

Force = Newton
1 kgf = 9.8 N
Process of finding force = Co position
Vector method = Polygon law force
Resultant force = sq.root (2P)
sigma H = Equilibrium
Sigma R = Not Equilibrium
Mass Moment of Inertia = kg-m2
Movement of inertia = m4

Important points of Engineering Mechanics

Moment of inertia rectangle to width = (1/12)bd3
Moment of inertia rectangle to depth = (1/12)db3
Moment of inertia sphere = (a4)/12
Moment of inertia of circle about diameter = (pi/64)d4
Moment of inertia of circle about axis = (pi/32)d4
Moment of inertia triangle about base = (bh3)/36
Moment of inertia triangle about axis = (bh3)/12
Moment of inertia solid sphere = (2mr2)/5
Ideal machine efficiency = 100%
Non reversible machine = self locking
Reversible machine <50%
Non reversible machine >50%
Screw jack is non reversible machine
Low power machine (P) = mW + c , P=effort , W= Load
Maximum advantage lifting machine = (1/m)
Max. efficiency of lifting machine = (1/m) X V.R.(Velocity Ratio)
Velocity ratio of 1st system pulley = 2^n
velocity ratio of 2nd system pulley = n
Velocity ratio of 1st system pulley = [(2^n)-1]
Velocity ratio screw jack = [(2 x pi x l)/P]
Redundant frame = imperfect
Time of flight of projectile = [2usin(alpha)]/g
Angle of banking = slope on rod surface provided on curve
Super elevation = When railway (roadway) path outer edge is always made higher than the inner edge to keep the vehicle equilibrium while in motion this raise is known as super elevation.
Work =(N-m = Joule) Force act on body and body tends to move in direction of force .
Power [(N-m)/s][watts] = rate of doing work.

Important points of Engineering Mechanics

Energy = Capacity of doing work.
Slope provide on road = angle of bank
D-Alembert principle = the resultant force acting on body together with effective reversal force are in equilibrium
Newton's First law = Everybody is continuous in state of rest or uniform motion in straight line unless it is acted by some of force
Newton;s second law = rate of change of moment is directly pro personal to impressed force takes place in the same direction in the direction of force.
Newton's third law = every action has equal and opposite reaction'
Mass = mater contains in body.
Weight = Force by which is attracted to words the center of earth.
momentum = mass X velocity

Law of static friction

it acts opposite direction of body
Force is exactly equal to force tends to move
constant ration to limiting friction
depends upon the roughness of surface
independent of area of contact

Law of Kinetic friction

Always acts opposite direction.
bear constant ration to normal reaction between two surface.

Important points of Engineering Mechanics

Engineering Mechanics

2020-03-27T21:41:00.001+05:30

Engineering Mechanics

Branch of engineering science which deals with principle of mechanics and application of engineering problems

There 2 types of Mechanics

1. Static mechanics: it Deals with force and there effect which deals at rest.

2. Dynamic mechanics: it Deals with force and there effect which deals at motion.

in dynamic there are 2 types

Kinetics: it Deals with force and there effect which deals at motion due to application of force
Kinematics: it Deals with force and there effect which deals at motion without taking in account force which responsible for motion.

Force : it produce or tends to produce , destroy of tends to destroy the motion of body, which acting on body.

Resultant force: it can be define by 3 system

Parallelogram law of force
Triangle law of force
Polygon law of force

Co planer force: W hoes line of action lies on the same plane.

Concurrent force: The force which meets at one point.

Non-Co planer force: W hoes line of action not lies on the same plane.

Non-Concurrent force: The force which do not meets at one point.

Engineering Mechanics

Lami s theorem:

3 co planer force acting at a point be in equilibrium each force is praposnal to sine of angle between two force

https://www.youtube.com/channel/UCTfk_SXHfvxYGuuPvM5Vb2Q?view_as=subscriber

Limit fit & Tolerance

2020-03-23T09:54:00.000+05:30

Limit fit & Tolerance :

Unilateral tolerance :variation is only one direction

Bilateral tolerance : variation on both side

Fundamental deviation: basic size

Tolerance = upper limit - lower limit :Permissible limit of variation for manufacturing is assigned to parts for manufacturing purpose as boundary of acceptable build.

Basic size: Nominal diameter of shaft or hole it is same for both

Fit: it is clearance between two mating parts, it can be determined by whether the parts move, temporary joint ,permanent joint.

Clearance fit: Hole is larger than shaft.

Transition fit: Hole is fractionally smaller than shaft.

Interference fit: Hole is smaller than shaft.

Functional dimension : have to be machined and fit with other mating parts.

Drilling : unilateral Dimension

BIS (Bureau of International Standard)

Grade of Tolerance :18

Fundamental tolerance : 25

BSI (British standard System)

Grade of Tolerance :16

Fundamental tolerance : 21

IS (International Organisation System)

Grade of Tolerance :18

Fundamental tolerance : 28

ES= Upper limit

EI = lower limit

https://youtu.be/69wgGf5xR5k

ENGINEERING DRAWING

2020-03-17T19:38:00.006+05:30

Engineering Drawing

Engineering Drawing is an Universal Language of Engineers to transfer Ideas.

Here there are lots of Different type of Sketch (projection) you can differentiate.
Prospective Projection :approximate representation view as you see by eye

Auxiliary View : use full in dislocation of portion (X-RAY)

Orthographic projection : visual ray line , parallel to each other

obliq and axonometric views : 3 view drawing

3 Principle plane
Frontal
Horizontal
Profile

Sphere has only ONE VIEW

Europe usually use :First angle view
Protector : 0.5 Degree Smallest Angle
Drafting Scale: Triangle is not available
Light Weight pencil : H
Drawing sheet Ration : 1: root2
Elevation = Top view Elevation on Vertical Plane

SHEET
A5 : 148 X 210
A4 : 210 X 297
A3 : 297 X 420
A2 : 420 X 594
A1 :594 X 841
A0 : 841 X 1189

Letter in Dwg : 7:4
3H,4H Pencil for : Center line
PENCIL IN ORDER : 18 Light Dark
9H,8H,7H,6H,5H,4H,3H,2H,H,F,HB,B,2B,3B,4B,5B,6B,7B
Drawing board Made by Ebony Material

There are Eight Types of Line
1. Continuous
2. Continuous thin
3. Short Dash
4. Long Chain
5. Chain Thick End
6. Short Chain
7. Continuous Wavy
8. Straight zig zag

ENGINEERING CURVE
e= Eccentricity
e=0, Circle
e=1 ,parabola
e<=1 , ellipse
e=>, Hyperbola

Two type of View
1. First Angle
2. Third Angle

in third Angle ( 2nd and 4th Quadrant is not used Because Top view and Front view overlap)
Top view = on Horizontal Plane
Front View = on Vertical Plane

Pictorial Projection
1. Isometric Projection (30 Degree to HP)
2. Oblique Projection (45 Degree to HP)
3. Perspective Projection

https://youtu.be/69wgGf5xR5k

RTO class 3 paper solution Mechanical -GPSC

2020-03-02T22:15:00.001+05:30

RTO class 3 paper solution Mechanical -GPSC

https://www.youtube.com/channel/UCTfk_SXHfvxYGuuPvM5Vb2Q

RTO class 2 Mechanical Paper soution GPSC

2020-03-02T21:52:00.000+05:30

Here is attached RTO class 2 paper solution for mechanical
Circled answer is right one

Add caption

20-26

Add caption

https://www.youtube.com/channel/UCTfk_SXHfvxYGuuPvM5Vb2Q?view_as=subscriber