Poros Edit

5/26/2018 Poros Edit

1/31Hamrock, Jacobson and Schmid1998 M cGraw-Hill

Shafting and Associated Parts

When a man has a vision, he cannot get the power from the vision until he has

performed it on the Earth for the people to see.

Black Elk, Oglala Sioux visionary, as told to John Niedhart.

Image: A crankshaft from an automotive diesel engine.



Shaft Assembly

Figure 11.1 Shaft Assembly.

(a) Shaft with two bearings at

A and B and two gears with

resulting forcesP1andP2;

(b) free-body diagram of

torque and forces resulting

from assembly drawing; (c)

moment diagram in x-z and

x-y planes; (d) torque

diagram.

Text Reference: Figure 11.1, page 425



Example 11.1

Figure 11.2 Illustration used in Example11.1. (a) Chain drive assembly; (b) free-

body diagram of forces; (c) bending

moment diagram.




Example 11.2

Figure 11.3 Figures used in Example 11.2. (a) Assembly drawing; (b)

free-body diagram.




Example 11.2 (cont.)

Figure 11.3 Figures used in

Example 11.2. (c) moment

diagram in x-y plane; (d)

moment diagram in x-z

plane; (e) torque diagram.




Fluctuating Stresses on

Shaft

Figure 11.4 Fluctuating normal and

shear stresses acting on shaft. (a)

Stresses acting on rectangular

element; (b) stresses acting on

oblique plane at angle .



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Hamrock, Jacobson and Schmid1998 M cGraw-Hill

Soderberg Line for Shear Stress

Figure 11.5 Soderberg line for shear stress.



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Illustration of Eq. (11.29)

Figure 11.6 Illustration of relationship given in Eq. (11.29).



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Example 11.4

Figure 11.7 Section of shaft used in Example 11.4.



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Single Spring-Mass System

Figure 11.8



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Example 11.5

Figure 11.9 Simply supported shaft arrangement used in

Example 11.5.



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Flat Key Assembly

Figure 11.10 Flat key assembly. (a) Cross-

sectional view of assembly of shaft, hub,

and key; (b) three-dimensional view of flatkey.



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Flywheel on Shaft

Figure 11.11 Flywheel with driving (mean) torque Tmand load

torque Tl.



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Coefficient of Fluctuation

Type of equipment Cf

Crushing machineryElectrical machineryElectrical machinery, direct drivenEngines with belt transmissionFlour milling machineryGear wheel transmission

Hammering machineryMachine toolsPaper-making machineryPumping machineryShearing machinerySpinning machineryTextile machinery

0.2000.0030.0020.0300.0200.020

0.2000.0300.025

0.030-0.0500.030-0.0500.010-0.020

0.025

Table 11.1 Coefficient of fluctuation for various types of equipment [Adapted from

Kents Mechanical Engineers Handbook (1969).]

Text Reference: Table 11.1, page 450


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Example 11.7

Figure 11.12 Load or output torque cariation for one cycle used

in Example 11.7.



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Materials for Flywheels

Material

Performanceindex, Mf,

kJ/kg Co mment

Ceramics 200-2000(compression only)

Brittle and weak in tension.Eliminate.

Composites: CFRPa

GFRPb

200-500

100-400

The best performance. A goodchoiceAlmost as good as CFRP andcheaper . Excellent choice.

Beryllium 300 Good but expensive, difficultto work, and toxic.

High strength steelHigh strength aluminumHigh strength magnesium alloysTitanium alloys

100-200100-200100-200100-200

All about equal inperformance. Steal and AL-alloys cheaper than Mg and Tialloys.

Lead alloysCast Iron

38-10

High density makes these agood (and traditional) selectionwhen performance is velocitylimites, not strength limited.

aCeramic-fiber reinforced polymer

Graphite-fiber reinforced polymer

Table 11.2 Materials for flywheels. [Adapted from Ashby (1992).]

Text Reference: Table 11.2, page 455


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Punch Press

Figure 11.13 Punch Press



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Torque Requirements of Press

Figure 11.14 Torque requirements of mechanical power press. (TDC=top

dead center, BDC=bottom dead center.)



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JENIS POROS

POROS BEBAN :

Beban Tetap dan Beban Berputar

Jenis Pembebanan : lenturan dan geseran


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POROS TRANSMISI


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Perhitungan Kekuatan poros :

Perhitungan kekuatan terhadap lenturan

Perhitungan kekuatan terhadap tekanan

bidang antara tap dan bantalan

Perhitungan kekuatan terhadap penyaluran

panas


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Perhitungan terhadap lenturan :

MOMEN INERTIA (I) d


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MOMEN INERTIA (I) dan

MOMEN TAHANAN BENDING (Wb)


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MOMEN TAHANAN POLAR


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Hamrock Jacobson and Schmid1998 M cGraw-Hill

Poros Edit

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