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ACME

ACME

NPT( NATIONAL PIPE THREADS)

NPT( National Pipe Threads)

Endurance limit or FATIGUE limit is the maximum stress that a member can with STAND for an infinite number of load applications without failure when SUBJECTED to COMPLETELY reversed loading.

Endurance limit or fatigue limit is the maximum stress that a member can with stand for an infinite number of load applications without failure when subjected to completely reversed loading.

To VARY the TORQUE at the ROAD VEHICLES.

To vary the torque at the road vehicles.

RANKINE’s THEORY of FAILURE is APPLICABLE for brittle materials. GUEST’s theory of failure is applicable for ductile materials.

Rankine’s theory of failure is applicable for brittle materials. Guest’s theory of failure is applicable for ductile materials.

An INCREASE in the SPEED of the OUTER WHEEL.

An increase in the speed of the outer wheel.

By PITCH CIRCLE DIAMETER.

By pitch circle diameter.

N = 0.2d + 3

n = 0.2d + 3

MASS and STIFFNESS.

Mass and stiffness.

UNIFORM wear condition is assumed because it LEADS to safer design.

Uniform wear condition is assumed because it leads to safer design.

MAXIMUM SHEAR STRESS THEORY.

Maximum shear stress theory.

1.25

1.25

To PREVENT RELATIVE axial MOVEMENT between the SHAFT and the bearing.

To prevent relative axial movement between the shaft and the bearing.

 NUMBER of STRANDS X number of WIRES in each STRAND.

 Number of strands x number of wires in each strand.

Allowance in LIMITS and fits refers to MAXIMUM CLEARANCE between SHAFT and HOLE.

Allowance in limits and fits refers to maximum clearance between shaft and hole.

When length of the MEMBER is INCREASED, the member may fail due to buckling even though the member is SYMMETRICAL in all RESPECTS and the load is concentric.

When length of the member is increased, the member may fail due to buckling even though the member is symmetrical in all respects and the load is concentric.

In HAZOP (Hazards and operatibility) study each and every conceivable process deviation from normal OPERATING condition of a SYSTEM having identical design intention, is thoroughly analysed for causes and consequence and required action plan to mitigate hazard/operability problems are SUGGESTED on the basis of available protective system.

In Hazop (Hazards and operatibility) study each and every conceivable process deviation from normal operating condition of a system having identical design intention, is thoroughly analysed for causes and consequence and required action plan to mitigate hazard/operability problems are suggested on the basis of available protective system.

COMPUTER is ABLE to store lot of INFORMATION and same can be retrieved fast.

It performs CALCULATIONS very fast. The design can be visualized on screen and any alterations made and its effects clearly seen. Thus OPTIMUM designs can be achieved much faster and these are thoroughly tested from all angles.

Computer is able to store lot of information and same can be retrieved fast.

It performs calculations very fast. The design can be visualized on screen and any alterations made and its effects clearly seen. Thus optimum designs can be achieved much faster and these are thoroughly tested from all angles.

Pipe threads are USED for pressure TIGHT joints and square threads for POWER TRANSMISSION.

Pipe threads are used for pressure tight joints and square threads for power transmission.

The PROFILES used for splines in machine ELEMENTS are STRAIGHT SIDED splines, triangular splines and in volute splines.

The profiles used for splines in machine elements are straight sided splines, triangular splines and in volute splines.

The torsional equation is, T/J = q/R = GӨ/L

Where,

T – Torsional moment (T is in N-mm)
J - POLAR moment of INERTIA (J is in mm⁴)
q – Shear stress in the element (q is in N/mm²)
r - Distance of element from centre of SHAFT (r is in mm)
G- Modulus of Rigidity (G is in N/mm²)
Ө – Angle of twist (Ө is in radians)
L – LENGTH of the shaft (L is in mm)

The torsional equation is, T/J = q/r = GӨ/L

Where,

T – Torsional moment (T is in N-mm)
J - Polar moment of inertia (J is in mm⁴)
q – Shear stress in the element (q is in N/mm²)
r - Distance of element from centre of shaft (r is in mm)
G- Modulus of Rigidity (G is in N/mm²)
Ө – Angle of twist (Ө is in radians)
L – Length of the shaft (L is in mm)

The bending MOMENT equation is, M/I = f/y= E/R,

Where,

M – Bending moment (M is in N-mm)
I - Moment of INERTIA about centroidal AXIS (I is in mm⁴)
f – Bending Stress (f is in N/mm²)
y - Distance from NEUTRAL axis (y is in mm)
E - YOUNG’s modulus (E is in N/mm²)
R - Radius of curvature (R is in mm)

The bending moment equation is, M/I = f/y= E/R,

Where,

M – Bending moment (M is in N-mm)
I - Moment of inertia about centroidal axis (I is in mm⁴)
f – Bending Stress (f is in N/mm²)
y - Distance from neutral axis (y is in mm)
E - Young’s modulus (E is in N/mm²)
R - Radius of curvature (R is in mm)

A PLANE which has no SHEAR STRESS is called PRINCIPLE plane the corresponding stress is called principle stress.

A plane which has no shear stress is called principle plane the corresponding stress is called principle stress.

C FRAME, CRANE HOOK.

C frame, crane hook.

In CURVED BEAM the NEUTRAL AXIS does not COINCIDE with the centroidal axis.

In curved beam the neutral axis does not coincide with the centroidal axis.

N curve has fatigue stress on ‘Y’ axis and number of loading CYCLES in ‘X’ axis. It is used to find the fatigue stress VALUE corresponding to a GIVEN number of cycles.

N curve has fatigue stress on ‘Y’ axis and number of loading cycles in ‘X’ axis. It is used to find the fatigue stress value corresponding to a given number of cycles.

It is the property of the material, which refers to a RELATIVE ease with which a material can be cut. It is measured in a number of ways such as COMPARING the TOOL life for CUTTING DIFFERENT material.

It is the property of the material, which refers to a relative ease with which a material can be cut. It is measured in a number of ways such as comparing the tool life for cutting different material.

They are USED to SOLVE the PROBLEMS of VARIABLE STRESSES.

They are used to solve the problems of variable stresses.

The FACTORS effecting notch SENSITIVITY are:

1. MATERIAL
2. Notch radius
3. Size of component
4. TYPE of loading
5. Grain Structure

The factors effecting notch sensitivity are:

NOTCH sensitivity (q) is the degree to which the theoretical effect of STRESS concentration is actually reached.

The RELATION is, Kf = 1 + q (Kt-1)

Notch sensitivity (q) is the degree to which the theoretical effect of stress concentration is actually reached.

The relation is, Kf = 1 + q (Kt-1)

Some of the methods are:

1. Avoiding sharp corners.
2. PROVIDING fillets.
3. Use of multiple holes INSTEAD of single hole
4. Undercutting the SHOULDER parts.

Some of the methods are:

The factors INVOLVED in arriving at factor of safety are:

1. Material PROPERTIES
2. Nature of loads
3. PRESENCE of localized STRESSES
4. Mode of failures

The factors involved in arriving at factor of safety are:

The FAILURE theories are:

1. MAXIMUM principal stress theory.
2. Maximum SHEAR stress theory.
3. Maximum principal STRAIN theory.

The failure theories are:

While SELECTING a material for a machine element, the following factors are to be considered

1. Required material PROPERTIES
2. Manufacturing ease
3. Material availability
4. COST

While selecting a material for a machine element, the following factors are to be considered

The different the MODES of fractures are:

1. Mode I (Opening mode) – DISPLACEMENT is NORMAL to crack surface.
2. Mode II (SLIDING mode) – Displacement is in the PLANE of the plate.
3. Mode III (Tearing mode) – Out of plane shear.

The different the modes of fractures are:

A CRACK can propagate if the energy RELEASE rate of crack is GREATER than crack RESISTANCE.

A crack can propagate if the energy release rate of crack is greater than crack resistance.

SIZE factor is used to consider the effect of the size on endurance strength. A large size OBJECT will have more defects compared to a SMALL ONE. So, endurance strength is reduced. If K is the size factor, then

Actual endurance strength = Theoretical endurance limit x K

Size factor is used to consider the effect of the size on endurance strength. A large size object will have more defects compared to a small one. So, endurance strength is reduced. If K is the size factor, then

Actual endurance strength = Theoretical endurance limit x K

Stress concentration is the increase in local STRESSES at POINTS of rapid change in CROSS section or discontinuities.

Stress concentration factor is the ratio of MAXIMUM stress at critical section to the nominal stress.

Stress concentration is the increase in local stresses at points of rapid change in cross section or discontinuities.

Stress concentration factor is the ratio of maximum stress at critical section to the nominal stress.

In brittle fracture, CRACK growth is up to a small depth of the material.

In DUCTILE fracture LARGE amount of plastic deformation is PRESENT to a HIGHER depth.

In brittle fracture, crack growth is up to a small depth of the material.

In ductile fracture large amount of plastic deformation is present to a higher depth.

The TWO TYPES of FRACTURE are

1. DUCTILE fracture
2. BRITTLE fracture

The two types of fracture are

Repeated stress refers to a stress VARYING from zero to a MAXIMUM value of same NATURE.

Reversed stress of cyclic stress varies from ONE value of tension to the same value of compression.

Repeated stress refers to a stress varying from zero to a maximum value of same nature.

Reversed stress of cyclic stress varies from one value of tension to the same value of compression.

TYPES of VARIABLE STRESSES are:

1. COMPLETELY reversed or cyclic stresses
2. Fluctuating stresses
3. Repeated stresses

Types of variable stresses are:

Factors AFFECTING endurance strength are

1. LOAD ii. SURFACE finish
2. Size
3. TEMPERATURE
4. Impact
5. Reliability

Factors affecting endurance strength are

Different loads on MACHINE COMPONENTS are:

1. STEADY load.
2. Variable load.
3. SHOCK load
4. Impact load.

Different loads on machine components are:

The VARIOUS phases of design PROCESS are:

1. Recognition of need.
2. DEFINITION of problem
3. Synthesis
4. Analysis and optimization
5. EVALUATION
6. Presentation

The various phases of design process are:

If the time of load APPLICATION is less than one third of the lowest natural PERIOD of vibration of the PART, it is called an IMPACT load.

If the time of load application is less than one third of the lowest natural period of vibration of the part, it is called an impact load.

ENDURANCE limit is the maximum value of COMPLETELY reversed stress that the standard SPECIMEN can sustain an infinite number (106) of CYCLES without FAILURE.

Endurance limit is the maximum value of completely reversed stress that the standard specimen can sustain an infinite number (106) of cycles without failure.

The RATIO between maximum STRESSES to working STRESS is known as FACTOR of safety.

Factor of safety = Maximum stress /Working stress

The ratio between maximum stresses to working stress is known as factor of safety.

Factor of safety = Maximum stress /Working stress

When a MATERIAL is subjected to REPEATED stress, it fails at stresses below the yield POINT stress; such type of failure of the material is called FATIGUE.

When a material is subjected to repeated stress, it fails at stresses below the yield point stress; such type of failure of the material is called fatigue.

It is the property of the material enabling it to be drawn into WIRE, with the application of tensile force. It must be both strong and PLASTIC. It is usually measured in terms of percentage elongation and reduction in area, (e.g.) NI, Al, and Cu.

It is the property of the material enabling it to be drawn into wire, with the application of tensile force. It must be both strong and plastic. It is usually measured in terms of percentage elongation and reduction in area, (e.g.) Ni, Al, and Cu.