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Solution proposal! - Division of Solid Mechanics - Linköping University

Solution proposal! - Division of Solid Mechanics - Linköping University

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Linköping <strong>University</strong><br />

Examination - TMHL08<br />

<strong>Solid</strong> <strong>Mechanics</strong>/IEI<br />

Finita Elementmetoden; grundkurs<br />

Bo Torstenfelt 2006-06-10<br />

Part II (Problem part)<br />

8. En rak 4L lång elastisk balk är belastad jämnt utbredd last/l.e. med en total<br />

resultant Q. Bestäm den vertikala kraften P på mitten av balken så att den vertikala<br />

förskjutningen under kraften blir lika med noll mha finit elementmetod. Hela<br />

balken skall indelas i fyra lika långa balkelement.<br />

(3p)<br />

Q<br />

E, I, 4L<br />

P<br />

v 2<br />

v 1<br />

θ 1<br />

v 2<br />

θ 2<br />

θ 3<br />

1 2<br />

v 3<br />

Gör följande frihetsgradsindelning.<br />

⎧ ⎫ ⎧ ⎫<br />

⎨ v 2 ⎬ ⎨ v 1 ⎬<br />

a L = θ 2<br />

⎩ ⎭ ; a S = θ 1<br />

⎩ ⎭<br />

v 3 θ 3<br />

pga.symetri<br />

Bilda elementstyvhetsmatriserna<br />

⎡<br />

K e 1 = K e 2 = EI<br />

⎢<br />

L 3 ⎣<br />

12 6L −12 6L<br />

4L 2 −6L 2L 2<br />

12 −6L<br />

4L 2<br />

⎤<br />

⎥<br />

⎦ 17.66<br />

Bilda elementlastvektorerna<br />

⎫ ⎧⎪ 6<br />

f e 1 = f e 2 = qL ⎨ ⎪⎬<br />

12 = L<br />

⎪ 6 ⎩ ⎪⎭<br />

−L<br />

17.71<br />

q = − Q 4L

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