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© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

ANSYS Structural Mechanics

Mark Leddin

ANSYS UK

© 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary

The Cost of Failure!


Agenda

• Products on offer

– Implicit

– Explicit

– Add-ons• Composites

• Fatigue

• Technology

– Elements

– Materials

– Contact

– Recent solver enhancements

– ANSYS Dynamics

– Explicit Dynamics

• Workbench

– Process flow and automation


ANSYS Mechanical FEA Suite

• Founded in 1970, ANSYS have been

developing generic Mechanical FEA software

for 40 years

• Originally developed for the nuclear industry,

quality was paramount in its design, now

in accordance with ISO quality controls

• ANSYS FEA has the broadest range of

capabilities in the market-place, with

technologies for:

– Linear & Nonlinear (geometric/material)

analyses

– Static, frequency-domain & time-domain

– 0-D to 3-D elements

– Isotropic, anistropic, layered materials

– ....


ANSYS Mechanical Solutions

ANSYS Mechanical solutions articulates the best in class CAE

products and technology for structural, thermal, acoustics

and coupled physics analysis that offers a unique class of

integrated simulation solution for the entire product

development process …


Product Offering/Target Users

• Built upon robust technology offers a range of products with a clear upgrade path from designers to

analyst.

ANSYS

Professional

PlanDrafting

CAD

Concept

Simulation

Virtual

Prototyping

Advanced

AnalysisEvaluate Production

ANSYS

DesignSpace

ANSYS

Structural

ANSYS

Mechanical

ANSYS

DesignSpace

Mid-RangeFront End High-End

ANSYS

Professional

ANSYS

Structural

ANSYS

Mechanical

ANSYS

Multiphysics

Functi

onality

/Pri

ce


Product/Technology Description

ANSYS

DesignSpace

ANSYS

Structural

ANSYS

Professional NLT

ANSYS

Mechanical

Linear Structural

Steady State Thermal

Linear Structural


Transient Thermal

Linear Dynamics

Linear Structural

Non-Linear Structural

Linear Dynamics

Nonlinear Dynamics

Linear Structural

Non-Linear Structural

Linear Dynamics

Nonlinear Dynamics


Transient Thermal

Acoustics

Direct Coupled

Solver Technology

ANSYS

Professional NLS

Linear Structural


Nonlinear Structural

Linear Dynamics


Explicit Analysis

• ANSYS Explicit Dynamics Products:o ANSYS Explicit STR, ANSYS LS-DYNA, ANSYS AUTODYN

• Short duration localized phenomena• Transient dynamic wave propagation

o Gases, Liquids, Solids and their Interaction (FSI)• Nonlinear

o Material behavioro Structural behavioro Contact/Interaction

• Extreme loadings• Extreme deformations

o Large strains & strain rateso Material failure

Courtesy of Sandia National Laboratory


ANSYS nCode DesignLife

• Premier fatigue analysis tool

• Analyze implications of repeated,

fluctuating, and rapidly applied loads,

which can result in failure or damage• Stress-Life (single, multi-curve, Haigh diagrams)

• Strain-Life (automated multi-axial corrections)

• Multi-axial safety factor (Dang Van)

• Seam welds and spot welds

• High temperature fatigue

• Vibration fatigue (shaker simulation)

• Multiple runs in a single analysis

• Complete duty cycles

• Multi-processor enabled for fast results

• Use Python for proprietary or custom methods


ANSYS Composite Prep/Post

• Composite materials

– Light

– Strong

– Good corrosion resistance

• Complex manufacturing

– Multiple materials

– Multiple directions

Composite examples

Simple geometry's easy to handle



• Take loaded FE model from

ANSYS Mechanical

• Build model as manufactured

– Ply by ply manufacture

– Draping

– Section cuts

• Use proven ANSYS FEA solver

• Post process using composite

criteria



• Composite specific

post processing

– Layer by layer

– User selected failure

mechanisms

– User defined failure

criteria


Geometry is imported in ANSYS Workbench. Loads and

boundary conditions are defined on the geometry.

ACP & FiberSim


Agenda


– Implicit

– Explicit


• Fatigue

• Technology

– Elements

– Materials

– Contact


– ANSYS Dynamics


• Workbench



Elements Technology

Solid Elements

2D Quad/Tri

3D – Hexa/Tetra/Wedge/Pyramid

Layered Solids

Solid Shell

Beam Elements

Multi material beam analysis

Beam Cross Section Definition

Shell Elements

Lower/Higher Order

Layered Shells

Special Elements

Rebars/Reinforcements

Links/Pipes/Springs

Cohesive Zone

User Elements

Gaskets


Materials Modeling

Material Models

Isotropic/Orthotropic Elasticity

Hyperelasticity

Plasticity

Viscoelasticity

Viscoplasticity

Creep

Other Models

Cast Iron Plasticity

Drucker-Prager

Shape Memory Alloy

USERMAT

Gasket Material

Concrete

Gurson DamageGasket Material

Hyperelastic Material


Material Models

Rate Dependent Chaboche Plasticity Model

• Based on Chaboche nonlinear kinematic

hardening model

• Plastic strain rate-dependent effects

• Captures cyclic hardening & softening

Applications/Benefits

• Applicable for turbine and engine design

• Simulation of ratcheting and shakedown

• Strain rate dependent applications, e.g.

impact simulations -3.E+08

-2.E+08

-1.E+08

0.E+00

1.E+08

2.E+08

3.E+08

-0.015 -0.010 -0.005 0.000 0.005 0.010 0.015

Str

es

sDisplacement


Material Models

• Response Function Model

• Chaboche Kinematic Hardening

• Anand Plasticity Model

• Gasket Material Model

• Temperature Dependency for

– BISO, BKIN,

– All Hyperelastic models

including Gent, Blatz-Ko, Arruda

Boyce

• Enhanced - Anisotropic Elasticity

UI to check for input error

Curve fitting support for

temperature dependent

Gasket


Contact Analysis

• Node-Node; Node-Surface; Surface-Surface; Line-Line; Line-Surface

• Small and Large Sliding

• Lower and Higher order elements

• Pure Penalty; Augmented Lagrange; Pure Lagrange; MPC contact

• Semi-Automatic Contact Stiffness Update

• Multiphysics Contact; Rigid Contact

• Friction Sliding (Small/Large Deformation)

• Shell/Beam Thickness Effects

• Contact Manager Wizard

• Automatic Assembly Contact


Contact Modeling

Fluid Pressure Penetration Support

Model fluid penetrating 2 contact surfaces

2D/3D surface-to-surface contact pair

Small and large sliding contact

Rigid-flexible and flexible-flexible contact

Usage

Pressure applied normal to contact & target

elements

Can be cut off when contact is restored or

contact pressure is larger than the fluid

pressure

Applications

Post-Leakage simulation

Sealing performance evaluation

Fluid pressure is applied

Fluid pressure is Not applied

Seals


Debonding and Contact

• Used with 2D and 3D contact elements

• Supports augmented Lagr., penalty methods

• Debonding can be used to model failure modes

– Mode I (normal) , Mode II (tangential) or Mixed mode

(mode I and mode II)

– Debonding is available for bonded contact

• Specified through TB,CZM


Fracture Mechanics

Enhancements to J-integral Calculations

Thermal strain is automatically included

in the J-Integral calculation

Surface pressure load on element

surfaces or edges is automatically

included in the J-Integral calculation

Benefits/Applications

Provide accurate estimation of J-Integral

when there are thermal strains and

surface pressures on crack faces

Structural integrity assessments

Nuclear reactor safety analysis

Spot Weld

Failure Analysis


Example

Turbine Blade Crack Analysis

PRCINT prints calculated

J-Integral values to

Solution Information

Window

Penny Crack


SNODE Solver for Modal Analysis

• Splits FE matrix in to smaller pieces –

SuperNodes

• Solves reduced eigenvalue problem

• Transforms eigenvectors back to the

original FE domain

Benefits

• Ideal for > 3 mil. DOFs , >500 modes

• Non-iterative – i.e. will not fail to converge

• Does not miss modes

Applications

• Beam, shell or thin geometries

• Automotive, aerospace

• High frequency response analysis, etc.

Advances in Solver Technology

0

20000

40000

60000

80000

100 1000 4000 8000

CP

U T

ime

Number of Modes

Block Lanczos

Supernode

Single Xeon 3.4 GHz processor

►17+ hours reduced to ~1 hour

►7 TB of I/O reduced to <300 GB


Cyclic Symmetry Support

• Static and Modal Analysis

Support

• Thermal-Stress Support

• Smart Boundary Constraints

Manager

• Expansion of the sector

• Travelling Wave animation

• Support Pre-stress Modal

Cyclic Symmetry

• Peak Holds Results


ANSYS Dynamics

Nonlinear Transient

DynamicsModal Harmonic Response

Modal Superposition

Linear Transient

DynamicSpectrum Harmonic Response

Response Spectrum Random Vibration

Rigid DynamicsFlexible Dynamics

(Implicit & Explicit)

ANSYS Dynamics


Common Uses

• Commonly used for

– Airborne electronics

– Acoustic loading of Airframe parts

– Jitter in alignment of optical equipment

– Relative deformation in large mirrors

Random Vibration Analysis


Power Spectral Density

• The Power Spectral Density is the mean

square value of the excitation for a unit

frequency band.

– The area under a PSD curve is

the variance of the response

(square of the standard

deviation).

– The units used in PSD are

mean square/Hz (e.g. an

acceleration PSD will have

units of G2/Hz).

– The quantity represented by

PSD may be displacement,

velocity, acceleration, force, or

pressure.Random Vibration curve by MIL-STD-202

Random Vibration Analysis


• Rigid Dynamics– Determination of Motion and Forces

• Assume no flexibility to parts• Large rotations and displacements• Full view of mechanism motions• Automated redundancy analysis

– Fast solves• Flexible Dynamics

– Determination of Motion, Forces, Deformations and Stresses• Nonlinear anything allowed (contact,

geometric, material)• Selectively define flexible bodies• High fidelity models

– Longer solves, but more details– CMS available to speed-up solves

• Control System Modeling– Links and co-simulation between

Simplorer and structural dynamics solutions

Rigid vs. Flexible Dynamics


Key Benefits of ANSYS Rigid Body

Dynamics

• Extremely Fast Solution

– Often measured in seconds for even

complex assemblies

• Efficient Model Setup Tools

– Configuration tool for manipulation of

assembly and identifying problems

– Ease of conversion from all-rigid to combined

rigid-flexible model

• Single integrated modeling environment

• Iterative "what if" simulations

– Parameterization allows rapid manual

optimization due to the very low CPU

requirements of an all rigid dynamics solution

• Wide industry applicability (automotive,

aerospace, robotics, biomedical ....)


Features

• Access within ANSYS Workbench

• Familiar user interface

• ANSYS AUTODYN solver

Benefits

• WB Native, data sharing with other

WB applications

• Short learning curve for WB users,

easiest explicit to learn

• Mature element/solver technology

Applications

• Impact events

• Highly nonlinear events

• Very short transients

ANSYS Explicit


Graphical User Interface

- Data Sharing between ANSYS systems

Persistent Data Sharing between ANSYS systems

Operational Load Case (Static)

Ultimate Load Case (Explicit)

Natural Frequencies (Modal)


Connections

- Sliding Contact

Features

• Trajectory contact method

• Nodes and faces are tracked during

computational cycle

• Penalty and Energy Conserving

• Optional Definition of Contact Regions

for Efficiency

• Body Self Contact

• Edge-on-Edge Contact

• Frictionless/Frictional, Static/Dynamic

• Eroding Contact

Benefits

• Simple/Automated definition

• Ease of use Workbench is famous forCourtesy FhG-EMI,

Germany


Features

Face groups/parts to be bonded

Normal/shear stress failure criterion:

Benefits

Connect dissimilar meshes

Model conditional connections

Model connection failures

Applications

Non-congruent meshes

Laminated components

Glue joints

Connections

- Breakable Bonded Contact

1

expexp

s

s

s

n

n

n

SS


Impact and Ballistic Protection

Normal and oblique HVI impact validations

For space vehicle shielding systems

• Example Application

– Hypervelocity Impact


Agenda


– Implicit

– Explicit


• Fatigue

• Technology

– Elements

– Materials

– Contact


– ANSYS Dynamics


• Workbench



ANSYS Workbench

• Being part of the ANSYS Workbench

infrastructure opens up several

enhancements in overall process for the

structural mechanics users

– Geometry

– Meshing

– Post-processing

– Reporting

– Process scripting & chaining

– Automatic Project updates


ANSYS Workbench


ANSYS Structural Mechanics

• ANSYS Structural analysis


DesignXplorer

• Start with a workbench defined process

– Use parameters in:

• CAD

• DesignModeler

• SpaceClaim

• Engineering data

• Preprocessor

• Postprocessor

• Derived parameters

– Define design envelope• Parameter limits

• Descrete/continuous

– Define goal• Near target

• Min/Max

• Trade offs


DesignXplorer

• DOE

– Select DOE type

– Custom + Sampling (OSF)

• Candidate designs

• Response surface

• Six Sigma analysis

– Manufacturing best/worst case


Summary

• 20 years ago

– 1 geometry > meshed by hand > 1 set of material properties >

worst case loading > evaluate stresses > assign safety factor

make design decision

• Today

– Import CAD geometry > auto mesh > ±3 variation in material

properties > ±3 variation in load values > durability assessment

make design decision

ansys structural mechanics uk/staticassets/fea... · ansys structural mechanics mark leddin ansys...

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