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SKRIPTA RIJEÅ ENIH ZADATAKA IZ OTPORNOSTI MATERIJALA

SKRIPTA RIJEÅ ENIH ZADATAKA IZ OTPORNOSTI MATERIJALA

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t<br />

29. Zadatak<br />

Odrediti potreban broj zakovica promjera 20 mm, ako je<br />

F<br />

F<br />

A<br />

F/2<br />

F/2<br />

F = 300kN<br />

1<br />

= 8mm<br />

t = 12mm<br />

τ<br />

σ<br />

dop<br />

dop<br />

τ =<br />

= 100MPa<br />

= 280MPa<br />

s<br />

F<br />

A<br />

F<br />

nmA<br />

F<br />

ndt<br />

F<br />

F<br />

= ≤ τ 2<br />

d π<br />

nm<br />

4<br />

F/2<br />

F/2<br />

d<br />

n – broj zakovica<br />

m – reznost zakovica<br />

n ≥ 5 → n = 6 → 2n<br />

= 12 → 2reda<br />

σ =<br />

p<br />

=<br />

=<br />

1<br />

dop<br />

3<br />

300 ⋅10<br />

=<br />

−3<br />

6 ⋅ 20 ⋅10<br />

⋅12<br />

⋅10<br />

F<br />

→ n ≥ 2<br />

d π<br />

m τ<br />

4<br />

−3<br />

dop<br />

= 208MPa<br />

≤ σ<br />

=<br />

dop<br />

t 1<br />

t<br />

t 2<br />

2<br />

−3<br />

( 20 ⋅10<br />

)<br />

4<br />

F<br />

300 ⋅10<br />

2<br />

= 280MPa<br />

3<br />

F<br />

π<br />

100 ⋅10<br />

6<br />

33

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