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ANSYS Explicit DynamicsUpdate
+1 512‐687‐9523
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• Introduction • Solve Problems that were Difficult or Impossible in the Past
– Structural Dynamics and Explicit Dynamics– Complex Interactions (Contact)
• Enhanced Productivity with Release 14– Speed Improvements – 2D Problems in Workbench– Easier Meshing – New TET element– Better Insight Into Results– Automation– New Physics
ANSYS Explicit Dynamics Update ‐ Outline
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Damage to products from impact
Consumer or commercial product drop
Manufacturing process with large plastic deformation
High speed fragment or object impact
High speed collision of large objects
Cracking of brittle materials in products
Explosion near structures
Problems Addressed by Explicit Dynamics
Complex reality made easy through simulation
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• Short duration localized phenomena• Transient dynamic wave propagation
o Gases, Liquids, Solids and their Interaction (FSI)• Nonlinear
o Material behavioro Contact/Interaction
• Large deformationso Large strains & strain rates
• Material failure
Nature of Explicit Dynamics Problems
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Explicit Dynamics, (like Structural Dynamics) models the response of structures: from quasi static to severe loadings
Applications in: Manufacturing, Consumer Products, Aerospace, Defense, Heavy Equipment, Oil and Gas, Turbo‐machinery, …
ANSYS Edge: User Productivity, Ease of Use, Seamless CAD to Solution Environment (ANSYS Workbench)
Used by small and large organization world wide, over 800 ANSYS Explicit Dynamics customers.
Used to design products, protect products, improve processes
What is ANSYS Explicit Dynamics
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Explicit Solution (Explicit Dynamics)• Time is an independent variable that is "explicitly" advanced according to a stability criteria limited by the speed of shock waves in the smallest element– Local Response
• From shock waves created by impact or other loadings• Resulting in deformation and material failure
Implicit Solution (Structural Dynamics, aka Mechanical)• Time is not an independent variable and is "implicitly" advanced according to convergence criteria– State variables being computed are not time dependent
• Collection of equations represent the relationship of all elements in the problem
• Equations solved “implicitly” with advanced matrix solutions– Global Response
• From loads applied mostly uniformly to the whole system.
Solution Methods Compared
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For Implicit Solutions
• model size (number of DOF)
• size respectively grade of nonlinearity
• number of time steps to simulate
For Explicit Solution
• size of the critical time step
‐ characteristic element length
‐ sound of speed in materials (Young’s moduli & density)
• model size (number of elements)
• Length of the physical time to be simulated
Factors Influencing Calculation Times
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• No convergence problems in highly nonlinear problems
• No equilibrium iteration needed
• Material failure and erosion easy to model
• High frequencies are naturally resolved because of small time steps
• Implicit‐explicit switching capability for efficiency
• Suited to a wide range of complex nonlinear problems
New Uses of Explicit Solver
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Explicit GUI is the Same as Structural
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• Drop test simulations – (short time dynamic range, high frequencies)
• Problems including complex contact situations – (large geometrical nonlinearities)
• Problems including sophisticated material damage and failure – (large nonlinearities, element erosion)
• Load limit analyses – (large deformations, large nonlinearities)
• Manufacturing simulations – (large deformations, large nonlinearities)
• High‐speed Dynamic analyses– (failure, fragmentation, blast wave‐structure interaction)
Extend the Range of Structural Problems
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Complex Contact Example – Crimping
Equivalent Stress
Effective Plastic StrainCrimping process of seven wires. Changing contact surfacesSelf contactSevere deformation
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Complex Contact – Failing Window Crank
Equivalent Stress
Effective Plastic Strain
Window Crank Mechanism
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Non‐linear Material Response
Hyper‐elastic CV Boot
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Material Failure and Complex Contact
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• Painless problem setup– Complex geometries easier to mesh with TET elements
• New NBS TET avoids shear locking
• Fast solutions using 2‐D• Insight into part interactions
– Reaction force trackers implemented
• Generalized Shell– Discrete element, variable thickness shells– Import Polyflow and other forming simulation results
• Direct Access to results for convenient analysis and processing• Composites
– Layered composites (shells)
Productivity Further Enhanced with R14
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New Tetrahedral Element
Nodal Based Strain (NBS) formulation• Overcomes both volume and shear locking• Particularly valuable in low velocity applications involving complex geometry (consumer drops like mobile phones, nuclear equipment drops)– Low deformations and bending dominates problems– Isotropic elasticity, plasticity including failure– Testing has shown that an Hourglass coefficient (Puso factor) of 0.1 should be used
• No longer Beta in Release 14
Painless problem setup
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NBS TET Accuracy – Beam Bending
Case Average End Deflection
%
ANP Tet ‐0.178 ‐21.1%NBS Tet ‐0.146 0.7%MAPDL ‐0.147 0.0%
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NBS TET Example – Self Piercing Rivet
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NBS TET Example – Drop Test, Tablet PC
Stress Contours Front View
Stress Contours Rear View, Cover Invisible
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2D Plain Strain and Axisymmetric solid analyses supported for Explicit Dynamics
• 2D pre‐ and post‐processing exposed• Plain Strain• Axisymmetric axis of symmetry now in y‐direction to be consistent with other ANSYS analysis types
Fast solutions using 2‐D
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Fast solutions using 2‐D – Bullet Example
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Direct and quick results of reaction forces
• Allows capture of high frequency content in response
• Scoped to Boundary Condition– Fixed, Displacement, Velocity, Remote Displacement
• Scoped to Geometry Selection– Reaction Forces, Contact Forces, Euler/Lagrange Coupling forces
• Results can be filtered
Insight into part interactions
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Example – Boundary Reaction Tracker
Force reaction at each of 4 supports of component subject to impact loading
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Example – FSI Force Tracker
External force time history due to fluid jet impinging on deformable surface (filtered at 10,000Hz)
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Import Shell Thickness from External Data
Example – Import from ANSYS Polyflow• Polyflow is a Finite Element based CFD tool used for simulating the processing of materials such as polymers, glass, metals and concrete
• Processes modeled include extrusion, blow molding, thermoforming, fibre drawing
• Polyflow results (of predicted thickness) can now be exported to Mechanical and Explicit Dynamics
Generalized Shell – Discrete Thickness
Blow Molding with Polyflow• Initial polymer J shape (above)• Final thickness (below)
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Import from Polyflow
Complete Virtual Prototyping and Testing capability in ANSYS Workbench for packaging manufacturing:
• Simulate blow molding or thermal forming process to get final thickness distribution
• Perform stress and deformation analysis with the variable thickness map (top load, crush, drop etc.)
Discrete Thickness Example
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Complete Virtual Prototyping in ANSYS Workbench• Simulate blow molding or thermal forming process to get final thickness distribution with POLYFLOW
• Perform drop test of product filled with water
Discrete Thickness Shell Example
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Design Assessment• Introduced in Workbench to enable customized post‐processing of Mechanical systems
• Programmable/scriptable means to access results• Explicit Dynamics can now be an upstream system for Design Assessment
Direct Access to Results
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Design Assessment – Display Fragments
Fragment Volume
Equivalent plastic strain
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Data Integration with ACP
ACP: Built upon a documented Workbench SDK, EVEN has developed addins to introduce ACP as a component system inside Workbench
Typical Workbench system: file management and standard actions like Update, Duplicate
Consume materials from Engineering Data
Composites
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ACP Workflow Example
Implicit (MAPDL)
Explicit * (Autodyn)
Parameter Support
Allows for inclusion as part of Design Exploration
Insertion into schematic flow
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Composite ExampleCFRP Baseball bat with spiral CRFP reinforcement
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ANSYS Explicit Dynamics • Extends the power of Structural Dynamics for Problems that were Difficult or Impossible in the Past
• Release 14 Provides Further Productivity Enhancements– Speed Improvements – Easier Problem Setup– Better Insight Into Simulated Results– Improved Automated Use– Convenient Composite Modeling
Summary