appendix dsgn04i04 part 2 2011

8/3/2019 Appendix DSGN04I04 Part 2 2011

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Appendix (Machine Design: DSGN04I04)

1

Design of Pressure VesselsInternally Pressurized Cylinders:Stresses in Thin-Walled Cylinders:

,

,

Stresses in thick-walled cylinder:

Externally Pressurized Cylinders:Stresses in thick-walled cylinder:

22

2

2 2

,max

22

2

2 2

2 2

,max 2 2

1

1

oi i

r

o i

r i

oi i

o i

i i o

o i

rp r

r

r r

p

rp rr

r r

p r r

r r

2 2

2 2 2

,max

2 2

2 2 2

2

,max 2 2

1

1

2

o o i

r

o i

r o

o o i

o i

o o

o i

p r r

r r r

p

p r r

r r r

p r

r r


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2

Rotating Cylinders:

Cylinder with Central Hole:

: mass denisty, kg/: rotational speed (rad/s)

Solid Shaft:

Recommended tolerances in millimeters for classes of fit:

Maximum and Minimum Shaft and Hub Diameters:


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3

Interference Fit:

Force and Torque:

Interference of press fit of hollow shaft to hub


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4

Fasteners and Power Screws

Power Screws: Pitch p: the distance from a point on one thread to the same point to

the adjacent thread.

: The thread angle.

Number of threads per inch n= 1/p

l= m*p, m: number of starts, l: lead

Helix angle ; l : lead The Tensile stress area:

The pitch diameter of an ACME power thread is: (in) (mm)


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5

Forces and Torque

Raising the Load:

Lowering the Load:

The power, in horse power:

The power, in watts:

Effieciency:

Self Locking Screws


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6

Strength of Steel Bolts:Proof strength: =0.8 * Yield strength


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7

UN Coarse and Fine Threads:

M Coarse and Fine Threads


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8

Design of Spur gearsSpur Gear Geometry:

Center distance: Circular pitch: Gear Ratio:

Diameteral pitch:

Module (m): Formulas for addendum, dedendum, and clearance (pressure angle, 20; full-

depth involute):

Loads on Gear Tooth

Bending Stresses in Gears

Modified Lewis Equation:


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9

AGMA Bending Stress Equation:

Application Factor

Size Factor


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10

Load Distribution Factor

Pinion Proportion Factor


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11

Pinion Proportion Modifier

Mesh Alignment Factor

Dynamic Factor


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12

Contact Stresses in Gears:

Gear Materials:


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13

Allowable Contact Stress:

Allowable Bending and Contact Stress:

Stress Modification Factors:


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14

AGMA recommends modifying the allowable bending stresses as follows:

AGMA recommends modifying the allowable contact stresses as follows:

Stress Cycle Factors, and :


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15

Reliability Factor:

Hardness Ratio Factor, :


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16

Power transmission and pinion speed relationship:


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17

Design of Helical GearNormal Circular Pitch:

Axial Pitch:

Equivalent Number of Teeth and Pressure Angle:

Helical Tooth Proportions:

Loads in Helical Gear:

AGMA Equations for Helical Gears:Bending Stress:

Pitting Resistance:


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18

Geometry Factors for Helical Gears:

Geometry factors Y and I for helical gears loaded at tooth tip.


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19

Design of Riveted and Welded Joints:Design of Riveted Joints:

Failure Modes for Fasteners in Shear:

Bending of Members:

Shear of Rivets (Single or Double):

Tensile Failure of Members:

Compressive Bearing Failure of Members:

Design of Welded Joints:

Fillet Weld:


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20

Shear Loading:

Bending Loading:

Electrode Properties:


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21


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22


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23

Design of Springs

Strength of Spring Materials

Deflection of Helical Compression Springs

Lengths and Forces in Helical Springs

Cyclic Loading

max 3 3

d w

Spring Index (meaure of coil curvature)

8 0.5 81

Transverse shear factor

K is replaced with curvature correction factor, K

4 1 0.615

4 4

d

d

w

DC

d

PD PDKd C d

K

CK

C C


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24

Design of Keys

310 for unpeened springs

465 for peened springs

se

se

S MPa

S MPa

1. Failure due to shear:

2. Failure due to compressive or bearing stress

design

The shear force acting on the Key

2

/ 2

The area for a key is . The design shear stress is

2

s

sy

s s

T TP

d d

A wl

SP T

A dwl n

design

The compression or bearing area of the key is

2

2

The compressive or bearing pressure is:

0.94

c

y

c s

lh TA

d

SP T

A dlh n


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25

Brakes and ClutchesThrust Disk Clutch

Uniform Pressure Model

Uniform Wear

Properties of Common Friction Materials

2 2o o iP p r r

2 3 32

23

o

i

r

oo o i

r

pT p r dr r r

3 3

2 2

2

3

o i

o i

r rPT

r r

2

o i

PT r r

2 a i o iP p r r r

2 2a i o iT p r r r


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26

Short-Shoe Brake

Band Brakes


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27


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28

Design of Keys

1. Failure due to shear:

2. Failure due to compressive or bearing stress

design

The shear force acting on the Key

2

/ 2

The area for a key is . The design shear stress is

2

s

sy

s s

T TP d d

A wl

SP T

A dwl n

design

The compression or bearing area of the key is

2

2

The compressive or bearing pressure is:

0.94

c

y

c s

lh TA

d

SP T

A dlh n

h

h

h

d: shaft diameter

l: key length


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Failure Prediction for Multiaxial Stresses

I. Ductile Materials

Maximum Shear Stress Theory (MSST):Also known as Tresca Yield Theory

1 3 1 2 3,y

s

S

n

Distortion-Energy Theory (DET):Also known as von Mises Yield criterion

appendix dsgn04i04 part 2 2011

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