Cosmos work designer

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5.86” & Vertical .46”,

both from top left corner

COSMOSWorks Designer Training

COSMOSWorks 2007

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2 © 2007 SolidWorks Corp. Confidential.

About this course

Prerequisites

Course Design Philosophy

Using this book

A note about files

Conventions used in this book

Class Introductions

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COSMOSWorks

Adv. Professional

Professional

Design Validation Products

Designer

Static

Vibration

& Buckling Thermal

Drop Test

Fatigue

Nonlinear

Post-dynamics

COSMOSEMS

Electromagnetic

COSMOSMotion

COSMOSFloWorks

Flow Simulation

Optimization

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What is Finite Element Analysis/ Design Validation ?

Example: Brick road from home to mailbox – measure the distance of a curved path using

yard stick

Curved path is approximated

by straight segments

Measure using a yard stick

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Building the FEA Model

CAD Model Stress Results

Defeaturing: suppressing or removing geometry

features deemed insignificant for analysis

(external fillets, rounds).

Pre-processing: Defining type of analysis,

material properties, loads, supports and restraints

Discretization: Meshing stage or

representing the solid model as finite

elements connected at node locations

FEA Post-Processing: Viewing

the different FEA result plots

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Building the FEA Model - Restraints

Represent how the given model is attached to the rest of the world

– Fixed on a Surface or Edge or Point

– Allow Sliding or Rotation

Restraints used to reduce the size of the problem to a component level or subassembly level

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Building the FEA Model - Loads

Loads applied to exterior surfaces of the model:

– Forces on Surfaces or Edges or Points

– Torque, Moment

– Pressure

Loads acting on entire model:

– Gravity, Centrifugal force

– Thermal loads

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FEA for structural analysis; Beam & Truss Element

Example of a frame structure Split the members of frame into

small straight pieces and

approximate the deformation

on each piece

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FEA for Thin Solid Model; Shell Element

Example of a bracket Split the surfaces of bracket

into small triangular pieces and


on each piece

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FEA for Thick Solid Model; Solid Element

Example of a fitting Split the fitting into small

tetrahedral pieces and


on each piece

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Mesh, Nodes, Elements, …

MESH – Approximate representation of the CAD geometry using Tetrahedra or Triangles

ELEMENTS – Tetrahedra or Triangles in the Mesh

NODES - Points at which different elements are jointed together; nodes are the locations where values of unknowns (usually displacements) are to be approximated

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Using Stress Results to Validate Design

Stresses at a point are defined by 6 quantities – 3 normal stress and 3 shear stresses – depend on orientation of coordinate system

Von Mises Stress =

VON is independent of coordinate system

Factor of Safety =

Principal Stresses – 3 normal stresses specified in a special coordinate system for which shear stresses are zero

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Assumptions in COSMOSWorks Designer

Response is proportional to the applied loads

– If you double the load, deformation also gets doubled

– If you remove the load, model has no deformation

Material is linearly elastic

– The part returns to its original shape if the loads are removed (no permanent deformation)

Loads are static

– Loads are applied slowly and gradually. Rapidly-applied loads cause additional displacements, strains, and stresses

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Check list for COSMOS Analysis

1. Material? – Steel 1040

2. Physical Working Condition? – Pressure or force

– Bolted or Welded

3. Modeling in COSMOS – TRAINING

4. Is my Design OK (Results) – Factor of Safety

– Stress



5.86” & Vertical .46”,


Lesson 1

Static Analysis of a Rectangular Plate with

a Hole

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Lesson 1 Topics

Introduction to the COSMOSWorks interface

Perform linear static analysis – Static study

Geometry

• Material properties

• Loads

• Restraints

Influence of mesh density on displacement and stress results

Post-processing

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Comparison between 2 different mesh

Study Name

Element Size,

in

No. of

element

No. of

nodes

No. of

DOF

Max Von

Mises Stress,

Psi

Max.

Displacement,

in

Mesh 1 - Default 0.225 6,986 12,152 35,901 6.03E+04 1.45E-01

Mesh 2 - Fine 0.1126 54,807 83,906 250,233 6.09E+04 1.45E+01

1. Decrease the element size would increase the number of nodes at the

FEA model. With more nodes, there will be an increase in the

computational time for calculation

2. As for the FEA result, both the max. von mises stress and displacement

value will converge to a finite value with increase in element size.

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Viewing the FEA result plots

Probe: Define the

plot result at node

locations

Iso-Clipping – View

the FEA result plot

within a specific

range of value

Section Clipping –

View the FEA result

at the cross-section

of the model

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Lesson 1 Results

von Mises Stresses in mesh 1 study

Why isn’t the stress plot exactly symmetric?

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Lesson 1 Results

Why is this stress plot more symmetric than the stress plots from the previous study?

von Mises Stresses in mesh 2 study

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Exercise 1



5.86” & Vertical .46”,


Lesson 2

Static Analysis of an L-Bracket

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Lesson 2 Topics

Using Configurations from SolidWorks

Use of mesh controls

FEA Convergence issues

no fillet

configuration fillet

configuration

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Lesson 2 Results

No fillet configuration

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Lesson 2 Results

Stress Results – mesh1, mesh2 and mesh3

1- When increasing the number of elements, will the stresses converge?

2- Why?

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Reaction Force

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Lesson 2 Results

Fillet, Mesh Control

No Mesh Control With Automatic Transition

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Exercise 2

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Exercise 3



5.86” & Vertical .46”,


Lesson 3

Contact/Gap Analysis of Pliers

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Lesson 3 Topics

Assembly Analysis Basics

Using Pin Connectors

Global and Local Contact/Gaps conditions

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Contact/Gap Hierarchy

You select a global contact setting that applies to all touching faces unless

otherwise changed by a component or a local face-to-face condition.

Component contact settings apply to all faces of a component that touch faces of other components. Component contact conditions override global contact settings.

Local contact conditions override global and component contact conditions. You can define local contact conditions for touching faces conveniently using the Find

contact sets Property Manager dialog.

mk:@MSITStore:C:/Program Files/COSMOS2006/help/cworks.chm::/Dialog_Box_Help/2006/Find_Contact_Sets.htm

mk:@MSITStore:C:/Program Files/COSMOS2006/help/cworks.chm::/Dialog_Box_Help/2006/Find_Contact_Sets.htm

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Lesson 3 Results

Von Mises stresses - No contact (50 lb force)

(You can plot stresses in exploded configuration)

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Lesson 3 Results

Could we study the stresses on contact surfaces?

Von Mises stresses – With contact (2000 lb force)

Determine the required force for the plier in contact

Using linear proportional

Displacement; in Force; lbs

0.02116 50

0.3 709

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Exercise 4



5.86” & Vertical .46”,


Lesson 4

Shrink Fit Analysis of a Wheel Assembly

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Lesson 4 Topics

Analyze shrink-fit problem

Use of symmetry

Review stress results in local coordinate systems

Solver options to eliminate rigid body modes

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Boundary Conditions

Symmetry restraint

Nodes at the specific face, not displacement

normal to plane

Use Reference Geometry

Define there is no axial displacement of the

components by reference of the defined

vertex.

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Local Contact Conditions

Contact conditions (global & local) – review

Contact conditions (local only) – Shrink fit

1 - Program creates a shrink fit condition between selected faces.

2 - The faces may or may not be cylindrical.

(NOTE: Virtual wall – a sliding support (roller), with friction and wall elasticity capability)

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Lesson 4 Results

Hoop stress (using local cylindrical coordinates)

Why is there a jump in the hoop stress value across the interface?

Would the assembly experience a similar jump in radial stresses?

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Soft Spring

Use soft spring to stabilize model

To fully constrain the rigid body in all direction

The model is surrounded by spring with

negligible stiffness compared to model

stiffness.

Comparison studies between shrink fit and use soft spring

Study Name Boundary Condition

Hub Rim

Shrink Fit Use reference geometry 16,015 16,009

Use soft spring Use soft spring 16,027 16,011

0.07% 0.01%

Contact Stress; psi



5.86” & Vertical .46”,


Lesson 5

Static Analysis of a Differential Assembly

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Lesson 5 Topics

Analyze larger assembly using solid elements

Remote load feature

Define multiple contact conditions

Nontraditional contact and connector use

Analyze mesh quality and question the results of the simulation

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Remote Load

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Pin Connector

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Lesson 5 Results

Draft mesh: mesh parameters and results

Mesh parameters and not good leading to exessive von Mises stress results

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Lesson 5 Results

High mesh: mesh parameters and results

Mesh parameters improved, so did the results of the simulation.

(NOTE: The time required to complete the simulation increased as well.)



5.86” & Vertical .46”,


Lesson 6

Shell Analysis of a Pulley

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Lesson 6 Topics

Shell Elements

Mid-plane and surface shell element meshing

Alignment of shell mesh

Evaluating mesh sizes

Evaluating results for shell elements

Reaction forces

Solid vs Shell meshing

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Shell Element Alignment

Misaligned shell elements

Shell Elements - Alignment

Incorrect stress result representation

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Lesson 6 Results

Top

Shell Elements – Von Mises Stress – Mid Plane

Bottom

Top (gray)

Bottom (orange)

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Lesson 6 Results

Shell Elements (surface) – Von Mises Stress

Top Bottom

Top (gray)

Bottom (orange)

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Lesson 6 Results

56259 DOF

Solid Elements – Von Mises Stress

878652 DOF

(1 element per thickness) (2 element per thickness)

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Lesson 6 Results

Shell vs. Solid Elements

Shell elements can greatly decrease the required computational time.

Modeling with shell elements is more demanding than with solids.

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Exercise 5



5.86” & Vertical .46”,


Lesson 7

Connectors, Special Supports and Contacts

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Lesson 7 Topics

Connectors

•Pins

•Bolts

•Springs

•Spot welds

•Links

Global and local contact conditions

Local contact with friction

Remote load

Anti-symmetric boundary conditions

Use of local coordinate systems

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Connectors - Pins

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Virtual Wall

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Pin Connector

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Lesson 7 Results (Pin Connector, Virtual Wall)

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Bolt Connector

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Lesson 7 results (Bolt Connector)

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Spring Connector

Simplify the model

1. Suppress the original helical spring from the analysis.

2. Introduce “Spring Connector”.

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Lesson 7 Results (Spring Connector)

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Spot Weld Connector

Connector types – Spot Welds

Spot Welds

Spot Welds

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Lesson 7 Results (Spot Welds)

Both solid models yield identical results.

Complete geometry Anti-symmetrical boundary conditions

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Key results

Spot Welds - solid models - stress results

We notice high stresses in the vicinity of welds. Would the subsequent mesh refinement in these regions bring more accurate stress distribution?

Mesh detail

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Key results

Spot Welds - shell model - stress results

Both solid and shell models predict similar behavior. Which one would you choose?

Mesh detail



5.86” & Vertical .46”,


Lesson 8

Mixed Meshing – Analysis of an Impeller

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Lesson 8 Topics

Why Mixed Meshing?

Some design assemblies may contain “bulky” parts suitable for solid mesh, as well as thin parts ideal for shell elements.

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Solid and Shell Elements

Compatibility problems in mixed solid and shell element meshing

Use of mixed mesh in analysis

How many DOF does a solid element have?

How many DOF does a shell element have?

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Mixed Meshing

Solid geometry must be prepared with mixed meshing in mind.

Notice the split lines and surface entities in the model.

Shell and solid surfaces are disconnected after meshing is complete.

Bonding must follow the meshing.

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Lesson 8 Results

Can Von Mises stresses be plotted in an arbitrary coordinate system?

Why are the stresses highest at the base near the support?



5.86” & Vertical .46”,


Lesson 9

Vehicle Suspension Analysis using

Design Scenarios

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Lesson 9 Topics

Design Scenarios – Performing several studies for different input data (model geometry or loads)

Stresses in vehicle suspension when vehicle is:

– Stationary and loaded

– Moving at constant acceleration on a smooth rod

– Moving on a bumpy road

– Moving at a constant speed on a banking

– Different loads in different directions

Review different connectors and restraints

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Design Scenario with loads input

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Lesson 9 Results (Loads input)

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Design Scenario with geometry input

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Lesson 9 Results (Geometry input)

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Exercise 6



5.86” & Vertical .46”,


Lesson 10

Adaptive analysis of a support bracket

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Lesson 10 Topics

Why and What is Adaptivity?

What do FEM results depend on?

1. Mesh

2. Type and order of the elements used (Draft or High quality)

3. Other phenomena (numerical errors, modeling errors etc.)

What is our Goal? Is it just to obtain a solution?

How to achieve it?

Make sure our results are close to some defined accurate solution. (typical parameter is strain energy density)

1. Modify and refine the mesh topology

2. Modify the “order” of elements

h-adaptivity

p-adaptivity

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Adaptive Finite Element Analysis

h-Adaptivity, p-Adaptivity

Refining the mesh (h-Adaptivity)

Changing the “order” of elements (p-Adaptivity)

1st order (Draft Quality)

2nd order (High Quality)

… 5th order

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Lesson 10 Results

h-Adaptivity - results

98% convergence criteria (2% accuracy) was achieved in 4 iterations

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Lesson 10 Results

p-Adaptivity - results

0.05% convergence criteria was/was not achieved in 4 iterations

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Lesson 10 Results

Summary

Max. displacement difference: 1.5%

Max. Von Misses stress difference: 9%

Which method would you use?



5.86” & Vertical .46”,


Lesson 11

Thermal Stress Analysis of a Bimetal Strip

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Lesson 11 Topics

Static analysis with temperature load

Use of various contact conditions

Temperature dependent material properties

Soft spring and Inertia relief options

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Lesson 11 Results



5.86” & Vertical .46”,


Lesson 12

Static Analysis of a Conveyor Frame

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Lesson 12 Topics

Beam Elements for Structural Members (Weldments)

Set up COSMOS study with beams - JOINTS

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Lesson 12 Results



5.86” & Vertical .46”,


Lesson 13

Large Displacement Analysis of a Clamp

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Lesson 13 Topics

Surface contact

Contact analysis with the large displacement option

Evaluate mesh adequacy for modeling bending stresses

Limitations of the linear material model

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Lesson 13 Results

Small displacement contact analysis – Incorrect Displacements

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Lesson 13 Results

Large displacement contact analysis – Correct Displacements



5.86” & Vertical .46”,


CONCLUSION

Cosmos work designer

Education

Transcript of Cosmos work designer