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fundamentos para o projeto de componentes de máquinas

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on<strong>de</strong>:<br />

⎧<br />

⎪32.<br />

n<br />

⎡<br />

⎛ T<br />

d = ⎨ . ⎢<br />

⎪ ⎢<br />

⎜<br />

π<br />

⎪ ⎣<br />

⎝ S<br />

⎩<br />

T = Torque (amplitu<strong>de</strong>)<br />

a<br />

T = Torque médio<br />

m<br />

M = Momento (amplitu<strong>de</strong>)<br />

a<br />

M = Momento médio<br />

am<br />

a<br />

e<br />

⎞<br />

⎟<br />

⎠<br />

2<br />

⎛<br />

⎜<br />

M<br />

+<br />

⎜<br />

⎝ S<br />

m<br />

y<br />

⎞<br />

⎟<br />

⎠<br />

2<br />

⎛ M<br />

+<br />

⎜<br />

⎝ S<br />

e<br />

a<br />

⎞<br />

⎟<br />

⎠<br />

2<br />

⎛<br />

⎜<br />

M<br />

+<br />

⎜<br />

⎝ S<br />

am<br />

y<br />

1<br />

3<br />

1<br />

2 ⎫<br />

2<br />

⎞ ⎤ ⎪<br />

⎟ ⎥<br />

⎟ ⎬<br />

⎠ ⎥<br />

⎦ ⎪<br />

⎭<br />

5.7 – EXERCÍCIOS RESOLVIDOS - CRITÉRIO DE FADIGA POR SODERBERG<br />

(32)<br />

1. Um eixo usinado é fabricado <strong>de</strong> um aço com Su = 550 MPa. Calcular n.<br />

Dado: T = 6,0 KN<br />

175.<br />

F 325.<br />

F<br />

R 1 = → R 1 =<br />

500 500<br />

σ = tensão alternada<br />

a<br />

σ max − σ min<br />

σ a =<br />

= σ max<br />

2<br />

Se<br />

n =<br />

σ<br />

σ<br />

a<br />

=<br />

a<br />

M<br />

I<br />

c<br />

= 100Mpa<br />

175.<br />

F<br />

M = R1<br />

. L = . 200 = 420KN.<br />

m<br />

500<br />

4<br />

3<br />

π.<br />

d<br />

I π.<br />

d<br />

I = on<strong>de</strong>: = e<br />

64<br />

c 32<br />

σ<br />

a<br />

e<br />

=<br />

K F<br />

a<br />

.<br />

M<br />

I<br />

c<br />

S K . K . K . K . K . S<br />

= ´<br />

b<br />

S e´<br />

0,<br />

504.<br />

S =<br />

u<br />

c<br />

d<br />

e<br />

e<br />

d<br />

c =<br />

2<br />

139

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