ANSYS Explicit Dynamics · PDF fileANSYS Explicit Dynamics Introduction ... –Well suited to simulate short dynamic events ... •Composite shell with variable thickness

© 2011 ANSYS, Inc. September 14, 2011

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ANSYS Explicit Dynamics

Peng Yuan, PhD

Senior Mechanical Specialist ANSYS, Inc.


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• Explicit Dynamics Introduction

• Comparison between the Explicit and Implicit Dynamics

• R14 new features

Presentation Outline


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Application range: from low to hyper velocity

Application area: consumer products, aerospace, defense, heavy equipment, oil and gas, automotive, turbo-machinery, …

ANSYS edge: a result of the focus on productivity, ease of use, and one integrated platform.

Many customers: over 800 customers using the ANSYS Explicit Dynamics worldwide

ANSYS Explicit Dynamics Introduction


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Formulation: Implicit vs. Explicit

t t t tM U C U K U R

Implicit

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2 2 2

2 2 2

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t t t t t tM C t K t M M C tU R U U

t t t

Leapfrog method

Explicit Eq. 1 is solved at time t to get U(t+∆t)

Eq. 1 is solved at time t+∆t to get U(t+∆t)

Equation of motion (1)

(2)


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Explicit Solution (Explicit Dynamics)

– Focus on local response and wave propagation

– Well suited to simulate short dynamic events

Implicit Solution (Structural Dynamics, aka Mechanical)

– Focus more on global response

– Suitable for static analysis, slower process or linear dynamics such as modal, harmonic…

Dynamics: Explicit vs. Implicit


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Implicit Solution

• Convergence controls.

- NR Iterations at t

• Solution time is unknown.

Explicit Solution

• Time step size controls.

- The CFL condition

- No iteration at t

• Solution time can be

predicted.

Computational Efficiency

Divergence


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Explicit Application Areas

Rapid loading

Strong coupling between fluid and structure

Shock wave propagation

Explosion / blast

Impact / penetration

Fragmentation / spallation

Spallation due to impact


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Explicit Dynamics Examples


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• Problems including complex contacts

– Difficult converging

• Problems with sophisticated material damage and failure

– Multiphysics

• Load limit analysis

– Highly nonlinear

• Metal forming

– Mesh distortion

• Hyper speed dynamic analyses

– Failure, hydrodynamic

Extending ANSYS Dynamics Capabilities

Crimping analysis


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Consistent GUI with Mechanical


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• New TET element

• 2D capability

• Reaction force trackers

• Composite shell with variable thickness

• Direct access to result database

New Features in New Release R14


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Nodal Based Strain (NBS) formulation with

isotropic elasticity and plasticity including failure

• Overcomes both shear and volume locking

• Particularly valuable in:

- Low velocity applications involving complex geometries

- Bending dominant simulations

*No longer beta in Release 14

New Tetrahedral Element*


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NBS TET Accuracy – Beam Bending

Case Average End Deflection

Error %

ANP TET -0.178 21.1%

NBS TET -0.146 -0.7%

MAPDL -0.147 0.0%


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Plain Strain/Stress or

Axisymmetrical

- About Y-Axis, consistent with ANSYS Mechanical

- 2D results 3D expansion

Solutions Using 2D Models


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• Scoped to boundary conditions

– Supports, velocity, remote displacement

• Scoped to geometry selections

– Contact forces, FSI coupling forces

Force Reaction Tracker

Fluid impact force time-history filtered

at 1.0E4 Hz


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Can import thickness from External Data and Polyflow

Variable Thickness of Composite Shells

Data Integration with ACP

- the ANSYS Composite Pre/Post Processing tool


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Design Assessment

• Customize post-processing of Mechanical systems

• Scriptable means to access results

Linked to Design Assessment

Fragment Volume

Linking DA


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ANSYS Explicit Dynamics:

• Extends the power of structural dynamics for problems that were difficult or impossible to tackle

• R14 provides productivity improvements on

– Solver speed

– Model settings

– Pre/Post processing

Summary


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Questions?

Thank you

ANSYS Explicit Dynamics · PDF fileANSYS Explicit Dynamics Introduction ... –Well suited to simulate short dynamic events ... •Composite shell with variable thickness

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