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SHAFTSLayout and Design for Stress

 José Luis Reséndiz Isassi

Arturo Muñoz Garcia

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SHAFT LA

•  The genera ayout of a shaft to acco!!odate shaft ee!ents s#eci$ed eary in the design #rocess in order to #erfor! a freeanaysis and to o"tain shear%!o!ent diagra!s&

•  The geo!etry of a shaft is generay that of a ste##ed cyinder

t'o ty#es of shafts( the hoo' shafts ) tu"es* and the soid sha

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SHAFT LA

•  The geo!etric con$guration of a shaft to "e designed is often re+ision of e,isting !odes in 'hich a i!ited nu!"er of chang!ade&

•  If there is no e,isting design to use as a starter- then the dete

of the shaft ayout !ay ha+e !any soutions&

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SHAFT D.SIG/ F0R S

• It is not necessary to e+auate the stresses in a shaft at e+ery ##otentiay critica ocations 'i su2ce&

•  3ritica ocations 'i usuay "e on the outer surface-at a,ia o'here the "ending !o!ent is arge- 'here the tor4ue is #rese

'here stress concentrations e,ist&

•  The "ending !o!ents on a shaft can "e deter!ined "y shear "ending !o!ent diagra!s

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SHAFT STRE

• 5ending- torsion- and a,ia stresses !ay "e #resent in "oth !iaternating co!#onents& For anaysis- it is si!#e enough to codi6erent ty#es of stresses into aternating and !idrange +on Mstresses&

•

 The 7uctuating stresses due to "ending and torsion are gi+en

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• Assu!ing a soid shaft 'ith round cross section- a##ro#riate geter!s can "e introduced for c- I, and J resuting in

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SHAFT D.SI/G F0R D8MAT

• It is "ased on resistance- it is controed "y the !9,i!u! sheatheory&

• Fragie !aterias shaft shoud "e designed "ased on the !9,i!stress theory

• Shatfs are su":ected to torsi;n- "ending and a,ia force&

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• For a,ia oads

•   )for soid shafts*

•   )for hoo' shafts*

•  

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• ASM. e4uation for hoo' shafts co!"ine torsion- "ending anoads- a##ying the !9,i!u! shear stress e4uation !odi$ed introducing shoc> factors-fatigue and cou!n&

•  

•   )for soid shafts*

•  

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For stationary shafts K  b K

 Tric>e oad ?&@ ?&

Sudden oad ?& % B&@ ?& %

For rotation shafts K  b K

 Tric>e oad ?& ?&

Sudden oad !inor ?& % B&@ ?&@ %Sudden oad higher B&@ % C&@ ?& %

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• ASM. s#eci$es that co!ercia Stee shaft

• Ss (permissible) E@@@ #si for shafts 'ithout >ey'ay

•  Ss (permissible) @@@ #si for shafts 'ith >ey'ay

• And shafts de$ned s#eci$cations(

Ss is the C@ the eastic i!it 'ithout going o+er the ?E the ast tracfor shafts 'ithout >ey'ay& These +aues !ust reduce B for shafts '

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•   1 L ??

•   1 L K ??

•  

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SHAFT D.SIG/ F0R RATI0

• It is "ased on the !9,i!u! #er!isi"e turn

•   )for hoo' shaft*

•   )for soid shaft*

•  

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 THA/ 08 F0R 08AT./TI0/