Structural Mechanics 145

Advances in ANSYS R14.5 Structural Mechanics Solutions

Mai DOAN

Jiaping ZHANG

• Large and Complex Models – Tree Filtering / Tagging Tree Objects / Connections Worksheet /

Object Generator / Sub modeling / Performance enhancement

• Customization – Acoustics ACT

• Linear Dynamics

• Material models

• Cyclic & Linear Periodic symmetry

• Fracture Mechanics

• Modeling Composite

• Additional Control for Contact Modeling

• Improved External Data Mapping

• Miscellaneous features in ANSYS Mechanical

Agenda

ANSYS Release 14.5 Structural Mechanics Highlights: Part 1

Mai Doan ANSYS Senior Application Engineer, Austin

Mai.Doan@ansys.com

Analysis of Large and Complex Models

Motivation

Many users deal with always larger models. Increased performance and usability is required at each step of an analysis in order to reduce the time from geometry to results. Various tools and techniques for efficiently managing large models.

• Tree Filtering • Tagging Tree Objects • Connections Worksheet • Object Generator • Submodeling • Performance enhancement

Tree Filtering

The Tree Filter:

• To streamline the management of tree objects, especially for large models, a tree filter can be used to find objects or to reduce the length of the tree that is displayed.

• Filter by: Name, Tag (discussed later), Type or State.

• Examples:

Filter by state = underdefined to find only those objects in the

Filter by type = results to only display result items.

Tagging

Tags are designations that can be assigned to any branch in the tree and used with the previously discussed filtering capability.

• Activate the tags icon from the “View” menu

With the tags view active, a new “tags” window is

displayed below the details window

Connections Worksheet The “Worksheet” for the connections branches (e.g. “Connections”, “Contacts”, “Joints”, etc.), now adds a preferences section to allow users to configure the worksheet display.

Connections Worksheet

New at v 14.5 is the Connection

Matrix

Object Generator The Object Generator uses an existing object in the tree as a template for replication.

Example: mesh size control on 1 of the holes.

• Highlight the tree object to be replicated (the Face Sizing)

and activate the Object Generator icon

• The object generator window opens and indicates objects will be

generated from the “Current Selection” (graphical selection)

Object Generator

After generating, the new objects are displayed graphically and they appear in the tree. The object names reflect that of the parent object along with the prefix chosen (if any).

In this example the object to be generated (the mesh size control) required only a single geometry selection, a face. Object generator can be used to apply BC where multiple scoping selections are required (e.g. contacts, bolt pretensions, beam connections, etc.).

Global Model Sub Model

Submodeling is a technique where a coarsely meshed model can be solved followed by a subsequent solution using only a portion of the coarse model with a more refined mesh. Submodeling is available for structural and thermal analysis types with solid geometry.

• Data can be transferred from a 2D coarse model [Full Model] to a 3D submodel.

Submodeling for local refinement

Performance enhancements. HPC and GPU

•Linux workstation : Two Intel Xeon X5677 processors (3.47 GHz, 8 cores total), 48 GB RAM, 2 NVIDIA Tesla C2075, Red Hat EL 6.1

2.1M DOF, Nonlinear Static Analysis

The sparse solver can take advantage of multiple GPUs to reduce solution time

Result file size reduction

Sample model: 778,400 10-node tet, 16,800 contact elements, 1,429,000 nodes (4,3 MDOF)

To reduce storage needs,

R14.5 stores single

precision element results.

This leads to result files up to 50% smaller

Faster post-processing

To save time when creating animations, the post-processing of models containing large number of bodies and elements has been improved to be up to 40% faster

Customization for Structural Mechanics ACT

Motivation

Companies want to include best practices in their simulation environment so as to provide the ability to use and re-use expert knowledge, beyond standard capabilities

Adding loads and boundary conditions

New loads and boundary conditions can be added to ANSYS Mechanical – for example acoustics boundary conditions

Add custom results

Create your own custom results such as a maximum admissible criteria based on a ratio of stresses vs a given material property (Rm…)

Encapsulate APDL scripts

! APDL_script_for_convection.inp ! Input parameters: esel,s,type,,10 cm,component,ELEM thickness = 0.005 film_coefficient = 200. temperature = 226.85 ! Treatment: /prep7 et,100,152 keyop,100,8,2. et,1001,131 keyo,1001,3,2 sectype,1001,shell secdata,thickness,10 secoff,mid cmsel,s,component emodif,all,type,1001 emodif,all,secnum,1001 type,100 esurf fini alls /solu esel,s,type,,100 nsle sf,all,conv,film_coefficient,temperature alls

Embed 3rd party solutions

External solvers or tools can be plugged into the Mechanical Interface

XML/Python based interfaces

XML File to create buttons and dialogs

Python scripts takes data from the tree and sends appropriate information to the solver

Now available!

ACT-based Extensions library : Customization forum enabling customers to upload/share their own Extensions ACT-based extensions posted on ANSYS customer portal:

→Acoustics →FE Info →Morphing →Advanced post-processing →Post-processing for beams…

ACT Acoustics extension can be used to create acoustic boundary conditions and defining fluid bodies (elements & material properties):

• Pressure

• Mass Flow

• Impedance

• FSI Interface

• …many more

• Fluid body (FLUID30, 220 or 221

elements according to the mesh)

ACT Acoustics Extension

Acoustic Body:

• Transform SOLID185 in FLUID30, SOLID186 in FLUID220 and SOLID187 in FLUID221 (EMODIF)

• Define Sound Velocity, Density and Dynamic Viscosity… (MP)

– Material properties can be temperature dependent

• Define Perforated material

• Define Reference Pressure (R)

• Define acoustic-structural coupling

• Define PML and PML options

ACT Acoustics Extension

ANSYS Linear Dynamics

Structural and Material-Dependent Damping

• Damping, both structural and material-dependent, includes: Alpha Damping, Beta Damping, and Constant Damping Ratio

Enhancements include: – Damping parameterizations

– Better analysis environment state checks

– Better warning/error messages alerting users whenever appropriate

– Better visibility handling of applicable damping with respect to analysis type and solution type

Harmonic solution time can be improved by using frequency sweep capability of VT

VT is only supported for FULL harmonic analysis, only available when FULL is selected in solution method

Harmonic solutions at different frequencies of VT is calculated based on one FULL harmonic solution

VT Harmonic Analysis

Material Models added in Workbench R14.5

• Enthalpy input in Transient Thermal analysis (Heat Transfer analysis)

February 8, 2013

• Shape Memory Alloy (SMA) Material Model a) This model is always available for Static Structural and Transient Structural analyses. b) Available for Modal, Linear Buckling, Random Vibration and Response Spectrum analyses when performed using linear perturbation. c) Two properties are added here i) Superelasticity ii) Shape Memory Effect

February 8, 2013

Hyperelastic Material Models These new models are available now for Static Structural and Transient Structural analyses.

• Ogden Compressible Foam Hyperelastic Material model i) Ogden Foam 1st Order

ii) Ogden Foam 2nd Order and iii) Ogden Foam 3rd Order are available.

• Extended Tube Hyperelastic Material model • Special Hyperelastic Material Model : Mullins Effect Mullins Effect is an extension to existing nearly and fully incompressible

hyperelastic models to model softening or damage.

February 8, 2013

Damage Model Two properties are supported for Static Structural and Transient Structural analyses. i) Damage Initiation Criteria ii) Damage Evolution Law

Cyclic and Linear Periodic Symmetry

• Through R14, large cyclic symmetry models would either post very slowly due to excessive use of memory and computation cycles during result expansion

• R14.5 enables the user to expand a fraction of the model

Cyclic symmetry

n = Controls the extent of expansion n Є [1, N] n = 0 for Program Controlled.

i = Controls display range (i, i + n – 1) i Є [1, N] i = 0 for Program Controlled

Example Expansions for N=13

4 sectors 7 sectors 13 sectors

You can now display and animate results over a fraction of the total symmetry expansions and incur a corresponding fraction of the memory and computational expense.

New Symmetry type created to simulate linear periodic models with structural translational symmetry in Mechanical using Symmetry Region object. The Low and High Boundaries of that object assumed to be identical, and they will be automatically meshed using Mesh Matched controls. During solution those matched nodes are coupled together using MAPDL CP command.

Linear Periodic Symmetry

The existed Symmetry Region object with new Symmetry type Linear Periodic shown together with old Symmetric and Anti- Symmetric types used before.

Linear Periodic Symmetry

Simple model with translational Symmetry which is described by Symmetry Region object with new Linear Periodic type is defined below.

Total Deformation Solution Results

The Total Deformation results are presented for two cases: first solution was done with new Symmetry object and the second one – without it. Symmetry exists No Symmetry

Post-processing with Symmetry Expansion

ANSYS Release 14.5 Structural Mechanics Highlights: Part 2

Jiaping Zhang ANSYS Structural Technical Support, Houston

Jiaping.Zhang@ansys.com

Outline

o Fracture Mechanics

o Modeling Composite

o Additional Control in Contact Modeling

o Improved External Data Mapping

o Miscellaneous features in ANSYS Mechanical

Outline

o Fracture Mechanics

Motivation Cracks and flaws can occur for several reasons:

• The material may be inherently defective

• Long term operation

• Environmental conditions

Static fracture mechanics calculation could be used to

• Determine maximum allowable flaw size

• Basic for fatigue crack growth

Crack in gas pipeline due to corrosion

Crack in welded joint

A crack inside ANSYS Mechanical is defined using a

• Pre-Meshed Crack object

• Crack object (Does not require geometry editing)

These objects can be inserted under the Fracture folder.

• Fracture Tool

o Stress Intensity Factors (K1, K2 and K3)

o J-Integral (JINT)

o Energy Release Rate (G1, G2 and G3) (VCCT)

Fracture Mechanics in ANSYS mechanical

Pre-Meshed Crack object

A Pre-Meshed Crack is based on a previously-generated mesh (Mesh object in the tree outline). • 2D analyses(could still used for 3D) • Meshes imported with FE Modeler Crack front is defined using a nodal named selection. Coordinate system is required : • Y axis of the coordinate system defines the crack

surface normal • origin of the coordinate system represents the open

side of the crack

Solution Contours: Number of contours for which you want to compute the fracture result parameters.

Crack Object Defines the semi-elliptical shape of the crack in three dimensional static analyses.

Base Mesh (Tetrahedrons quadratic elements) will then be modified to create a crack mesh.

The crack mesh generation is performed after the creation of the base mesh.

…Crack Object

•Coordinate system •Crack definition

•Major and Minor radius •Largest contour radius •Circumferential divisions •Mesh Contours •Crack front divisions •Solution contours

•Buffer Zone

…Crack object

Buffer Zone: It represents the zone in which the elements will be removed to insert the crack template. The transition between the crack and the base mesh will be filled with elements.

Small “buffer zone”

Rapid mesh transition

Larger “buffer zone”

Smooth mesh transition

Post Processing for crack

Path Plot and Graphic visualization of:

o Stress Intensity Factors (K1, K2 and K3) o J-Integral (JINT) o Energy Release Rate (G1, G2 and G3)

Outline

o Modeling Composite

Motivation

• Light weight • Corrosion resist • Fire protection • Impact resistant

Carbon fiber umbilical (Courtesy from Aker Solutions)

Phenolic gratings used on a tension leg platform (Courtesy from Strongwell)

Multi-Layer composite pipe (Courtesy from MLC Pipes)

Excellent attributes for composites:

High pressure gas accumulator bottles used in Riser tension assembly (Courtesy of Lincoln composites)

Composite Integration in Workbench

Preprocessing Simulation Postprocessing

Evaluate the Composite Design • Evaluate Stresses in the Layer • Evaluate Failure Criteria

Build up the Composite Design • Define the Composite Layup • Define Fiber Directions

Extrude Shell to Solid inside ACP

Launch Mechanical

•Material, Mesh from ACP is consumed in system B •Geometry is synthesized in B •Solid composite section from ACP is imported into B

In the case of thick composites, the layered shell theory can cause significant errors in the obtained results.

Extruded Solid in ACP

Maintain topology between shell & solid model

Extruded Solid in Mechanical now has same face topology as shell

Post Processing in ACP-Post

• ACP Post will share the material, geometry and Model with ACP Pre (System A) • Solution from Static Structural (System B) will be used by ACP Post for post processing

Post processing in ACP-Post

Composite

Composite Non-composite inside Mechanical Assembling composite and other materials together in Mechanical

Progressive Damage Analysis in Workbench

Result Support in Mechanical Material Support in Engineering Data

Parameterization in ACP Pre-Post

Define parameters in ACP Pre and Post

Outline

o Additional Control in Contact Modeling

Motivation

Structural engineers need to go deeper and further in the detailed analysis of a given assembly, especially to better investigate connections

“Trim Contact” automatically reduces the number of contact elements generated within each pair, thereby speeding up processer time.

“Program Controlled” will typically turn Trim Contact ON. However, no trimming is done for manually created pairs and/or when Large Deflection is turned ON.

WB Mechanical – Trim Contact

…WB Mechanical – Penetration Tolerance

Penetration Tolerance: • Contact compatibility is satisfied in normal

direction if normal penetration is within allowable tolerance (TOLN )

• Can be defined as a Factor (of underlying element depth )or as a Value.

• Default =0.1*element depth (surf-surf) • Only exposed for Aug Lagrange

Formulation.

npenetrationormalnormal xkFAugmented Lagrange:

…WB Mechanical – Elastic Slip Tolerance

Ftangential

ELSIkF tangentialtangential

Elastic Slip Tolerance: • Contact compatibility is satisfied in

tangential direction if Elastic Slip (ELSI) is within allowable tolerance (SLTO) • Defined as a Factor of average

underlying element length or as a value

• Applies to bonded, rough and frictional contact behaviors to enforce compatibility in tangential direction.

• Default SLTO=1% of average element length

…WB Mechanical – Shell Thickness Effect

Shell Thickness Effect

• Applies only to surface bodies

Shell Thickness Effect = NO Shell Thickness Effect = Yes

…WB Mechanical - Connection Matrix

New Connection Matrix in the Connections Worksheet

Fluid Pressure Penetration Visualization

New contact result for fluid pressure penetration in the contact tool

Command snippets are still required to apply the loading to create this result

No Fluid zone

Fluid zone

WB RBD – Joint Technology Enhancements Nonlinear Springs:

(RBD stands for Rigid Body Dynamics)

Efficient modeling of small clearance between shaft and bearings are available for spherical, general and bushing joint and do not require full contact modeling

WB RBD – Joint Technology Enhancements

Contact properties can be defined using User Programmable Functions or by tabular input for real constants (FKN, CNOF, TCC etc.) as function of time, temperature, pressure, gap/penetration etc.

MAPDL- Contact Tabular Real Constants

• Example: User defined FKN vs Contact Pressure

… MAPDL- Contact Tabular Real Constants

*DIM,CNFKN_top,TABLE,6,1,1,PRESSURE CNFKN_top(1)=0.1,0.08,0.07,0.07,0.05,0.04 !FKN CNFKN_top(1,0)=1,5,10,50,100,150 !Contact Pressure RMODIF,cid,3,%CNFKN_top%

MAPDL – User Routine Enhancements Enhancements to User-Defined Friction (USERFRIC):

• Supports structural and non-structural degrees of freedom

• The frictional stresses can be defined as a function of the slip increments and the contact/target temperatures.

New USERINTER Routine:

• Define complex interactions between contacting surfaces when the existing interaction models are not adequate. Supports Normal/Tangential Directions and Coupled multi-physics applications.

New USERCNPROP Routine :

• Program your own real constants for all current-technology contact elements (CONTA17x).

- Perform any nonlinear contact pressure/penetration operation instead of a linear operation (that is, use a varied contact stiffness instead of a constant stiffness). The contact stiffness can vary with pressure, penetration, temperature, and your own defined state variables.

Outline

o Improved External Data Mapping

Motivation

Exchange files are frequently used to transfer quantities from one simulation to another.

Efficient mapping of point cloud data is required to account for misalignment, non matching units or scaling issues.

Users can import displacement and force data from external files into Mechanical using the External Data system

Support for Displacement and Force Transfer

Worksheet view to specify the components and scale results

Unavailable data can be ignored

Users can import pressure data and apply in a downstream harmonic analysis

Ability to prescribe real and imaginary components (normal to and defined by components)

Import Pressure in a Harmonic Analysis

Choice of coordinate system for vector data alignment

Default is “Source CS”

UY in Source CS

Any Local CS including Cylindrical

UY in Local Cylindrical CS

2D-3D Mapping • Imported vector data are transformed for 2D-3D mapping.

• Unavailable data can be ignored in the definition.

Z Component ignored because imported data only available for X and Y components

Further options to validate the mapping

Additional visual tools have been implemented to control how well the data has been mapped onto the target structure.

Isolines comparizon

Components display

Contours display

Improved mapping performance

Kriging weighting calculations now use multiple cores to faster results. For larger meshes utilizing 8 cores, a 6 to 7 time’s speedup can be obtained.

# Source nodes # Target Nodes R14 (1 Core) R14.5 (8 cores) Speedup

207602 79152 41.46 8.27 5.01

387419 437816 366.94 48.18 7.62

2570789 526082 3510.19 462.53 7.59

240178 700911 336.25 50.11 6.71

378779 4457975 3289.4 424.96 7.74

• The only file with the coordinate information is regarded as the master file. • The rest of them will have data to be mapped against the Node IDs. • This removes the requirement of storing coordinates in each file.

Mapping multiple data sets: Concept of a master file

Outline

o Miscellaneous features in ANSYS Mechanical

The user can now use the Named Selection worksheet to find nodes and geometry items using a “Distance” criteria. The distance is calculated from the origin of the selected coordinate system.

Note: The distance when searching for bodies, faces, edges, and vertices is calculated from the centroid of that item.

Distance Criteria For Named Selections

Hide/Show options on Named Selections

2D Pretension Bolt Loads Pretension Bolt loads can now be applied in 2D Analysis

Surface Force(Moment) Reaction Probe

Display annotation improvement Maximum annotation=50, with different colors

From Left to right: 1. Create a View 2. Delete View(s) 3. Apply a View 4. Rename 5. Replace saved view based on current

graphics 6. Import Views from a formatted xml in disk 7. Export Views as a formatted xml to disk

Added Manage View

Show Errors Button New Button in the toolbar to populate message window with explanation for under-defined objects. In prior release, a solution had to be invoked to populate the window.

Check ANSYS 14.5 release notes

Thank you!

Structural Mechanics 145

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