Chapter13, Książki, MES, !! ansys bardzo fajne, Finite Element Simulations with ANSYS Workbench 13, ebook, pdf

[ Pobierz całość w formacie PDF ]
Chapter 13 Nonlinear Simulations
1
Chapter 13
Nonlinear Simulations
13.1 Basics of Nonlinear Simulations
13.2 Step-by-Step: Translational Joint
13.3 Step-by-Step: Microgripper
13.4 More Exercise: Snap Lock
13.5 Review
Chapter 13 Nonlinear Simulations
Section 13.1 Basics of Nonlinear Simulations
2
Section 13.1
Basics of Nonlinear Simulations
Key Concepts
•
Contact Types
•
Contact versus Target
•
Nonlinearities
•
Contact Formulations
•
Causes of Structural Nonlinearities
•
Additional Contact Settings
•
•
Steps, Substeps, and Iterations
Pinball Region
•
Newton-Raphson Method
•
Interface Treatment
•
Force/Displacement Convergence
•
Time Step Controls
•
Solution Information
•
Update Stiffness
•
Line Search
Chapter 13 Nonlinear Simulations
Section 13.1 Basics of Nonlinear Simulations
3
Nonlinearities
e
}
•
[1] In a linear
simulation, [
K
]
(slope of the line)
is constant.
In a nonlinear simulation, the
relation between nodal force {
F
} and
nodal displacement {
D
} is nonlinear.
•
we may write
Displacement {D}
⎦
{ }
=
{ }
K
(
D
)
⎣
•
Challenges of nonlinear simulations
come from the difﬁculties of solving
the above equation.
e
}
[2] In a nonlinear
simulation, [
K
] (slope
of the curve) is
changing with {
D
}.
Displacement {D}
Chapter 13 Nonlinear Simulations
Section 13.1 Basics of Nonlinear Simulations
4
Causes of Structural Nonlinearities
•
Geometry Nonlinearity
•
Due to Large Deﬂection
•
Topology Nonlinearity
•
Contact Nonlinearity
•
Etc.
•
Material Nonlinearity
•
Due to Nonlinear Stress-Strain
Relations
To include geometry
nonlinearity, simply
turn on <Large
Deﬂection>.
Chapter 13 Nonlinear Simulations
Section 13.1 Basics of Nonlinear Simulations
5
Steps, Substeps, and Iterations
[1] Number of
steps can be
speciﬁed here.
•
Steps (Load Steps)
•
Each step can have its own analysis settings.
•
Substeps (Time Steps)
•
In dynamic simulations, time step is used
for integration over time domain.
[2] To switch
between steps,
type a step number
here.
•
In static simulation, dividing into substeps is
to achieve or enhance convergence.
•
Iterations (Equilibrium Iterations)
•
Each iteration involves solving a linearized
equilibrium equation.
[3] Each step
can have its
own analysis
settings.
[ Pobierz całość w formacie PDF ]

Podobne