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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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• Rigid Bodies
• Joints
• Forces
• Concentrated Elasticity
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• Static
• Kinematic
• Dynamic
• Computation of Eigenmodes/-frequency
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Integrate the resulting Nonlinear Differential Algebraic Equations to obtain the trajectories
of the rigid bodies
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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- The flexibility of a component can be an important aspect in a multibody
system, e.g.
- to recognize resonances,
- accurately simulate forces acting on the components
- accurately simulate the motion of the components
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
80
20
60
15
ADAMS
ANSYS
LS-DYNA
10
40
20
5
)
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-20
-5
-40
-10
-60
-15
-20
-80
-100
0
0.01
0.02
0.03
0.04
0.05
0.06
Zeit (sec)
0.07
0.08
0.09
0.1
0
0.01
0.02
0.03
0.04
0.05
Zeit (sec)
0.06
0.07
0.08
0.09
0.1
0.07
0.08
0.09
0.1
100
20
15
50
ADAMS
ANSYS
LS-DYNA
10
0
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ADAMS
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-5
-100
-10
-150
-15
-20
0
0.01
0.02
0.03
0.04
0.05
Zeit (sec)
0.06
0.07
0.08
0.09
0.1
-200
0
0.01
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
1
Z
X
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Y
0.02
0.03
0.04
0.05
Zeit (sec)
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•
Spring-Damper Elements: this element attaches between points specified on each
of the two bodies connected by the element. Force is produced that acts on a line
between the two points.
•
Bushing: The Bushing element is a six degree-of-freedom spring-damper force
between two bodies.
•
Beam: The Beam element is a six degree-of-freedom force between two bodies,
based on simple beam theory.
•
Flexible Body: Complete flexible linear subsystem including mass. Number of
DOFs corresponds to number of active modes imported from FE. The flexible
bodies experience linear elastic deformation in addition to nonlinear large
displacement motion
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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•
•
•
•
precise mass distribution and inertia coupling
controllable number of DOFs
possible to compare with Experimental Modal Analysis
controllable damping ratio for each mode
•
Only small deformations of flexible body is considered
• Assumption: 90% of combined Rigid+Flexible simulations are within small
deformations of the flexible component
• Nonlinear geometrice effects with multiple flexible bodies
Contacts between flexible bodies and rest of model not easy to model
Most MBS programs rely on FEM software -> 2 programs to handle
•
•
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
MBS model with
flexible body
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Work done by:
Adrian Vetter and Prof. Heiner Frommer of the Zürcher Hochschule Winterthur
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
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Spalthöhe am Z y linderaustritt H 1
D ruckdif f erenz dp
Spaltquerschnitt am Zy linderaustritt F1
Position ZA
Integral
Pos. Z A
Ventilspaltquerschnitt F2
Position KE
Pos. KE
Substitution d
kin. Viskosität nü
rho
H1
F1
H1
Integral
F1
F2
Integral
d
F2
nü
d
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Variabl en 1
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c
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Substitution c
c
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Vari ablen 2
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rho
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Position KE
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Position ZA
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Position Schl
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Nockendrehzahl
Winkel beschl
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Zyl i nderanfang
Resul tate
Zyl i nderanfang
Resul tate
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
Hngzkdng"Dqfkgu"kp"ODU
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Modell mit Starrkörpern
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Modell mit flexiblen Körpern
-2.00E+05
-2.50E+05
0.011
0.012
0.013
0.014
0.015
0.016
0.017
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
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5.00E+04
0.00E+00
-5.00E+04
-1.00E+05
Simulation
-1.50E+05
Messung
-2.00E+05
-2.50E+05
0.011
0.012
0.013
0.014
0.015
0.016
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CAD-FEM UsersMeeting 2003 / CAD-FEM AG / Marc Brandenberger
0.017
0.018
0.019
0.02
0.021
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