VCS 3D SIMULATIONS
Visual Crash Studio
3D Constructors
Visual Crash Studio-Overview
Macro Elements:
Beams and Joints
Honeycomb barriers:
MDB & ODB
Rigid bodies
New integration
schemes (explicit)
Global scalar and
vector fields
Contact/impact
modeling
SuperJoint Constructor - Modeling concept
Crashing response of joint element
involves interaction of:
• denting
and
• lateral crushing
of thin walled shells “weak response”
and
•beam-like response
of
• joint legs
(“strong response”).
Correctly designed joint should show “strong
response” under assigned crash loading. The NCS
joint module is developed to help engineers design
“strong-response” of joints.
SuperJoint Constructor - The mechanics of SuperJoint Element
Connecting shellConnecting shell
The interaction between “strong” and “weak” response is controlled by parts of the
joint referred to as “connecting shells”
The SuperFolding Elements II are used to model the transition
between joint legs and connecting shells
The SuperFolding Elements II are used to model the transition
between joint legs and connecting shells
SuperJoint Constructor
Constructors of deformable barriers - Overview
VCS implements three deformable barriers according to the following specifications:
MDB FMVSS 214
MDB 96/27/EC
ODB IIHS/EEVC
Visual Crash Studio
Simulation module
Setting up 3D simulation model - Basic procedures
1. Define 3D nodes & fixed b.c. 2. Define SBE 3. Split SBE on longitudinals
4. Add engine mounts (solid cross
section beam)
5. Add rigid bodies: engine and
gearbox
6. Add radiator and barrier nodes
& corresponding b.c.
Setting up 3D simulation model
Basic procedures - rigid bodies options
7. Add radiator and barrier (rigid
boxes)
8. Add nodes of wheel objects. 9. Add wheels (cylinders)
Define global fields contact settings and contact characteristics
Global model fields and general contact
Free fall in gravitation field
Earth gravitation
defined along Z axis
Contact flags of rigid
bodies set to false
Sphere and cylinder
penetrate fixed
parallelepiped
Global model fields and general contact
Intuitive contact definition 1
Contact flags of ALL rigid
bodies set to true
Multiple contacts flag set
to false
Cylinder bounces back
from green box
Sphere penetrates both
rigid bodies
Global model fields and general contact
Intuitive contact definition 2
Contact flags of ALL rigid
bodies set to true
Cylinder bounces back
from green box
Sphere contacts cylinder
and bounces back
Cylinder hits the box
second time
Multiple contacts flag set
to true
Global model fields and general contact
Contact Pairs
Contact pair defines
exclusive contact between
two selected elements
(based on standard law or
user defined characteristic
•2 contact pairs defined:
cylinder-box and sphere-
box. Sphere penetrates
cylinder
•3 contact pairs defined.
Contact detected between
all elements
Setting up 3D simulation model
Contact settings in elementary model of front end
Contact spheres (node window)
and bumper barrier contact
pairs
Contact spheres and wheels
longitudinals contact pairs
Contact spheres (node window)
and bumper barrier contact
pairs
Bumper radiator contact pairs Complete model Results of simulation
Contact/Impact procedures
Contact envelopes
In VCS the default beam contact algorithm
uses the concept of envelopes.
The envelope consists of:
• cylinder and
• sphere
that surrounds one half of the beam element
together with corresponding node. The radius
of the envelope is defined as an average
width of the cross section and can be
modified by the user for specific contact
models.
Setting up 3D simulation model
Contact envelopes for deformable barrier contact
Replace rigid barrier by IIHS (rigid
contact pairs removed automatically)
Set contact envelopes for
deformable barrier contact
Results of central crash test
simulation
Close up on contact area Offset crash scenario Offset crash simulation
Modified explicit integration scheme
Richard Courant and stability condition for linear
p.d.e.
Born: 8 Jan 1888 in Lublinitz, Germany (now Lubliniec, Poland)
Died: 27 Jan 1972 in New Rochelle, New York, USA
LC
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Critical time step:
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Discrete Continuous
oVtV )0(
Modified explicit integration scheme
Stability condition for nonlinear material response and
reversal point analysis.
Perfectly plastic and viscous materials (monotonic loading)
Nonlinear elastic
elastic/plastic material
(monotonic loading,
unloading and reloading)
Perfectly plastic and viscous materials (monotonic loading)
Nonlinear elastic
elastic/plastic material
(monotonic loading,
unloading and reloading)
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point is necessary
Modified explicit integration scheme
Details: kinetic and internal energy of an Element .
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nodes
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Basic assumption of explicit scheme:
Kinetic and internal energy of an Element
z
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z
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Kinematics of representative d.o.f. at iteration step
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Modified explicit integration scheme
Details: energy production and reversal point analysis.
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Classic elastic material and Courant condition
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:
2
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k
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oo
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Discrete version of Courant
stability condition
Note that m is a mass of the
node, u is an incremental
deformation and PI is a
contribution of given d.o.f. to
total potential energy of an
element.
Advanced modeling options
Kinematic constraints and concentrated loadings
Constraints and loadings can be assigned to all d.o.f. in a given group or
to a specific d.o.f. as explained in the table below
• set the same kinematic constraints to all d.o.f.
• set the same kinematic constraints to linear velocities
• set kinematic constraints for y d.o.f.
This procedure is the same for an individual node or a group of nodes.
Constraints and loadings can be assigned to all d.o.f. in a given group or
to a specific d.o.f. as explained in the table below
• set the same kinematic constraints to all d.o.f.
• set the same kinematic constraints to linear velocities
• set kinematic constraints for y d.o.f.
This procedure is the same for an individual node or a group of nodes.
Advanced modeling options - Complex loading histories
0–10 [ms] Bezier function 10–20 [ms] constant velocity 20–30 [ms] linear deceleration0–10 [ms] Bezier function 10–20 [ms] constant velocity 20–30 [ms] linear deceleration