6 lect6 truss students

background image

Computational Methods

1D Examples

Małgorzata Stojek

Cracow University of Technology

March 2013

MS

(L-53 CUT)

Beam & Truss

03/2013

1 / 44

Truss Example

3

2

5

1

4

EA

EA

y

x

1

1

1

2EA

2EA

EA

1

2

3

4

P

MS

(L-53 CUT)

Beam & Truss

03/2013

20 / 44

background image

Truss Discretization

3

2

5

1

4

EA

EA

1

1

1

2 EA

2 EA

EA

x

y

1

2

4

3

u

u

u

u

u

u

u

u

1

2

3

4

5

6

7

8

no elem.

nodes

global DOFs

length

α

c

=

cos α

s

=

sin α

1

1, 3

1, 2, 5, 6

2

π

/

4

2/2

2/2

2

1, 2

1, 2, 3, 4

1

0

1

0

3

3, 2

5, 6, 3, 4

1

π

2

0

1

4

2, 4

3, 4, 7, 8

2

π

/

4

2/2

2/2

5

3, 4

5, 6, 7, 8

1

0

1

0

MS

(L-53 CUT)

Beam & Truss

03/2013

21 / 44

Truss Element Library

Prismatic Bar

Stiffness Matrix

:

K

e

=

EA

L

c

2

cs

c

2

cs

cs

s

2

cs

s

2

c

2

cs

c

2

cs

cs

s

2

cs

s

2

=

EA

L

c

2

cs

c

2

cs

s

2

cs

s

2

c

2

cs

symm

s

2

Load Vector due to q

(

x

)

:

constant

distributed load

q

(

x

) =

q

F

e

q

=

qL

2

c

s

c

s

MS

(L-53 CUT)

Beam & Truss

03/2013

22 / 44

background image

Element Stiffness Matrix

K

e

1

4

×

4

=

K

e

4

4

×

4

=

EA

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

K

e

2

4

×

4

=

K

e

5

4

×

4

=

EA

1

0

1 0

0

0

0

0

1 0

1

0

0

0

0

0

K

e

3

4

×

4

=

EA

0

0

0

0

0

1

0

1

0

0

0

0

0

1 0

1

MS

(L-53 CUT)

Beam & Truss

03/2013

23 / 44

Assembly

Global Stiffness Matrix

K

=

0

8

×

8

(+)

K

e

1

4

×

4

(+)

K

e

2

4

×

4

(+)

K

e

3

4

×

4

(+)

K

e

4

4

×

4

(+)

K

e

5

4

×

4

F

q

=

0

8

×

1

(no distributed loads)

Before assembly

K

=

0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0

MS

(L-53 CUT)

Beam & Truss

03/2013

24 / 44

background image

no elem.

global DOFs

1

1, 2, 5, 6

K

e

1

4

×

4

=

EA

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

K

=

EA

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

0

0

0 0

0

0

0 0

0

0

0 0

0

0

0 0

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

0

0

0 0

0

0

0 0

0

0

0 0

0

0

0 0

MS

(L-53 CUT)

Beam & Truss

03/2013

25 / 44

no elem.

global DOFs

2

1, 2, 3, 4

K

e

2

4

×

4

=

EA

1

0

1 0

0

0

0

0

1 0

1

0

0

0

0

0

K

=

EA

2

2

+

1

2

2

+

0

1 0

2

2

2

2

0 0

2

2

+

0

2

2

+

0

0 0

2

2

2

2

0 0

1

0

1 0

0

0 0 0

0

0

0 0

0

0 0 0

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

2

2

2

2

0 0

0

0

0 0

0

0 0 0

0

0

0 0

0

0 0 0

MS

(L-53 CUT)

Beam & Truss

03/2013

26 / 44

background image

no elem.

global DOFs

3

5, 6, 3, 4

K

e

3

4

×

4

=

EA

0

0

0

0

0

1

0

1

0

0

0

0

0

1 0

1

K

=

EA

2

2

+

1

2

2

1

0

2

2

2

2

0 0

2

2

2

2

0

0

2

2

2

2

0 0

1

0 1

+

0

0

0

0

0 0

0

0

0

1

0

1

0 0

2

2

2

2

0

0

2

2

+

0

2

2

+

0

0 0

2

2

2

2

0

1

2

2

+

0

2

2

+

1

0 0

0

0

0

0

0

0 0 0

0

0

0

0

0

0 0 0

MS

(L-53 CUT)

Beam & Truss

03/2013

27 / 44

no elem.

global DOFs

4

3, 4, 7, 8

K

e

4

4

×

4

=

EA

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

K

=

EA

2

2

+

1

2

2

1

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

1

0 1

+

2

2

2

2

0

0

2

2

2

2

0

0

2

2

1

+

2

2

0

1

2

2

2

2

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

1

2

2

2

2

+

1

0

0

0

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

MS

(L-53 CUT)

Beam & Truss

03/2013

28 / 44

background image

no elem.

global DOFs

5

5, 6, 7, 8

K

e

5

4

×

4

=

EA

1

0

1 0

0

0

0

0

1 0

1

0

0

0

0

0

K

=

EA

2

2

+

1

2

2

1

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

1

0 1

+

2

2

2

2

0

0

2

2

2

2

0

0

2

2

1

+

2

2

0

1

2

2

2

2

2

2

2

2

0

0

2

2

+

1

2

2

+

0

1

0

2

2

2

2

0

1

2

2

+

0

2

2

+

1

+

0

0

0

0

0

2

2

2

2

1

0

2

2

+

1

2

2

+

0

0

0

2

2

2

2

0

0

2

2

+

0

2

2

+

0

MS

(L-53 CUT)

Beam & Truss

03/2013

29 / 44

Assembly

Generic System of Linear Equations

Kd

=

F

q

=

0

K

=

EA

2

2

+

1

2

2

1

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

1

0 1

+

2

2

2

2

0

0

2

2

2

2

0

0

2

2

1

+

2

2

0

1

2

2

2

2

2

2

2

2

0

0

2

2

+

1

2

2

1

0

2

2

2

2

0

1

2

2

2

2

+

1

0

0

0

0

2

2

2

2

1

0

2

2

+

1

2

2

0

0

2

2

2

2

0

0

2

2

2

2

det K

=

0,

rank

(

K

) =

5

MS

(L-53 CUT)

Beam & Truss

03/2013

30 / 44

background image

Boundary Conditions

kinematic constraints

external nodal forces

(essential "BCs")

(natural "BCs")

u

1

=

0,

u

2

=

0,

u

4

=

0

at node no 4,

P

=

10

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0
0

u

3

0

u

5

u

6

u

7

u

8

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0

P

MS

(L-53 CUT)

Beam & Truss

03/2013

31 / 44

Solution I

EA

2

2

+

1

2

2

1

0

2

2

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

1

0

1

+

2

2

2

2

0

0

2

2

2

2

0

0

2

2

1

+

2

2

0

1

2

2

2

2

2

2

2

2

0

0

2

2

+

1

2

2

1

0

2

2

2

2

0

1

2

2

2

2

+

1

0

0

0

0

2

2

2

2

1

0

2

2

+

1

2

2

0

0

2

2

2

2

0

0

2

2

2

2

0

0

u

3

0

u

5

u

6

u

7

u

8

=

0

0

0

0

0

0

0

P

MS

(L-53 CUT)

Beam & Truss

03/2013

32 / 44

background image

Solution II

EA

1

+

2

2

0

0

2

2

2

2

0

2

2

+

1

2

2

1

0

0

2

2

2

2

+

1

0

0

2

2

1

0

2

2

+

1

2

2

2

2

0

0

2

2

2

2

u

3

u

5

u

6

u

7

u

8

=

0

0

0

0

P

+

EA

1

0

2

2

2

2

2

2

0

2

2

2

2

1

0

0

2

2

0

0

2

2

0
0
0

MS

(L-53 CUT)

Beam & Truss

03/2013

33 / 44

Solution III

Solution is:

u

3

u

5

u

6

u

7

u

8

=

1

EA

P

P

2

+

1

P

P

2

+

2

P

2

2

+

3

d

=

0

0

u

3

0

u

5

u

6

u

7

u

8

=

1

EA

0

0

P

0

P

2

+

1

P

P

2

+

2

P

2

2

+

3

MS

(L-53 CUT)

Beam & Truss

03/2013

34 / 44

background image

Reactions at Supports

W

=

Kd

F

q

=

K

1

EA

0

0

P

0

P

2

+

1

P

P

2

+

2

P

2

2

+

3

0

=

0

P

0

2P

0

0

0

P

MS

(L-53 CUT)

Beam & Truss

03/2013

35 / 44

Equations of Equilibrium

2

3

4

P

1

1

1

x

y

1

0

P

2P

i

P

i

y

?

=

0

P

+

2P

P

=

0

i

M

i

1

?

=

0

2P

·

1

P

·

2

=

0

i

M

i

4

?

=

0

P

·

2

2P

·

1

=

0

MS

(L-53 CUT)

Beam & Truss

03/2013

36 / 44

background image

Postprocessing in Global Coordinate System

Siły przyw ˛ezłowe W

−→

W

e

x

1

,

W

e

y

1

α

−→

W

e

x

2

,

W

e

y

2

W

e

=

W

e

x

1

W

e

y

1

W

e

x

2

W

e

y

2

=

K

e

d

e

F

e

q

=

K

e

d

e

MS

(L-53 CUT)

Beam & Truss

03/2013

37 / 44

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0

0

P

EA

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

no elem.

nodes

global DOFs

1

1

,

3

1, 2

,

5, 6

EA

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

0
0

P

(

2

+

1

)

EA

P

EA

=

P

P

P
P

x

y

1

3

1

P

P

P

P

pr ˛et rozci ˛agany

P

2

MS

(L-53 CUT)

Beam & Truss

03/2013

38 / 44

background image

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0

0

P

EA

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

no elem.

nodes

global DOFs

2

1

,

2

1, 2

,

3, 4

EA

1

0

1 0

0

0

0

0

1 0

1

0

0

0

0

0

0
0

P

EA

0

=

P

0

P

0

2

2

1

P

P

x

y

pr ˛et ´sciskany

P

MS

(L-53 CUT)

Beam & Truss

03/2013

39 / 44

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0

0

P

EA

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

no elem.

nodes

global DOFs

3

3

,

2

5, 6

,

3, 4

EA

0

0

0

0

0

1

0

1

0

0

0

0

0

1 0

1

P

(

2

+

1

)

EA

P

EA

P

EA

0

=

0

P

0

P

3

3

2

P

P

x

y

pr ˛et ´sciskany

P

MS

(L-53 CUT)

Beam & Truss

03/2013

40 / 44

background image

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0

0

P

EA

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

no elem.

nodes

global DOFs

4

2

,

4

3, 4

,

7, 8

EA

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

1
2

2

P

EA

0

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

=

P
P

P

P

x

y

4

4

2

P

P

P

P

pr ˛et ´sciskany

P

2

MS

(L-53 CUT)

Beam & Truss

03/2013

41 / 44

u

1

u

2

u

3

u

4

u

5

u

6

u

7

u

8

0

0

P

EA

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

no elem.

nodes

global DOFs

5

3

,

4

5, 6

,

7, 8

EA

1

0

1 0

0

0

0

0

1 0

1

0

0

0

0

0

P

(

2

+

1

)

EA

P

EA

P

(

2

+

2

)

EA

P

(

2

2

+

3

)

EA

=

P

0

P

0

5

3

4

P

P

x

y

pr ˛et rozci ˛agany

P

MS

(L-53 CUT)

Beam & Truss

03/2013

42 / 44

background image

Sprawdzenie

Siły przyw ˛ezłowe w pr ˛etach.

Reakcje wi ˛ezów, obci ˛a˙zenia w ˛ezłów.

3

3

2

P

P

2

2

1

P

P

4

4

2

P

P

P

P

5

3

4

P

P

1

3

1

P

P

P

P

x

y

x

y

2

3

4

P

1

0

P

2P

Równowaga w ˛ezłów:

P

1

P

1

P

2

1

P

1

P

2

P

3

4

P

2

2P

4

P

P

1

P

1

P

3

P

5

3

P

4

P

4

P

5

4

P

MS

(L-53 CUT)

Beam & Truss

03/2013

43 / 44

Axial Forces

Gl obal i z ati on : Force Tran s form ati on

N o de f o rces tra ns f o rm a s

x

y

i

j

f

xi

f

yi

f

xj

f

yj

f

yi

f

xi

f

xj

f

yj

α

_

_

_

_

T

=

c

s

0

0

s

c

0

0

0

0

c

s

0

0

s

c

f

x

i

f

y

i

f

x

j

f

y

j

=

c

s

0

0

s

c

0

0

0

0

c

s

0

0

s

c

f

x

i

f

y

i

f

x

j

f

y

j

W

e

=

T

W

e

MS

(L-53 CUT)

Beam & Truss

03/2013

44 / 44


Wyszukiwarka

Podobne podstrony:
6 lect6 truss students
5 lect6 beam students
5 lect6 beam students
2010 ZMP studenci
gruźlica dla studentów2
Prezentacja 2 analiza akcji zadania dla studentow
Szkolenie BHP Nowa studenci
Student Geneza
Kosci, kregoslup 28[1][1][1] 10 06 dla studentow
higiena dla studentów 2011 dr I Kosinska
Studenci biegunka przewlekła'
WYKŁAD STUDENCI MIKULICZ
Wyklad FP II dla studenta
Inwolucja połogowa i opieka poporodowa studenci V rok wam 5
Materiały dla studentów ENDOKRYNOLOGIA

więcej podobnych podstron