ME 450 GroupAdrian ConradChris Cook Thomas HyltonNathan Wagers

High Pressure Water FixtureConceptual Design Analysis

December 10, 2007

Design Objectives

• Demonstrate understanding of FEA through ANSYS Workbench.

• Analysis had to prove that the current design was safe to operate under applied pressures.

• Maximum stress would be below yield strength, therefore preventing plastic deformation.

• Final analysis would allow for proper modifications to the fixture’s overall design.

Introduction

• High Pressure Water Fixture designed to flow water through interior of an airfoil to clean out any extra debris.

Introduction

• 4,000 psi water flowing into fixture.• Stainless Steel fixture material.• Arbor adjustability• Fixture Dimensions: - Height: 4.5” - Length: 12”

- Width: 5”

Element Types

•186 and 187 type elements•Used for Curved Surfaces•More nodes allows surface conformability

4 Node Tetrahedral Element 10 Node Tetrahedral Element

Utilized Theory

• Maximum Displacement– For u, v, & w components

• Von Mises Stress

Utilized Theory Contd…

• Strain

Where:

And:

Model Details

• Pro/E Model– Assembly of 34

Components

• IGES File Creation– Solid Type

FEA Tool: ANSYS Workbench

• Why?– Efficient Meshing• Automatic Mesh

– Ease of Use for Refinement• Large Contact Edges• Arbor Bottom Edges

IGES File Import

Large Contact

Long Rods

IGES File Import (2)

Arbor

Base Side

Large Contact

s

Socket Bolt

Swivel

Base Top

Long Rods

Arbor Cap

Swivel Case

Model Details: Material

Stainless Steel AISI 304

Mechanical Properties

 

T (°C)

Density (×1000 kg/m3) 8 25

Poisson's Ratio 0.27-0.30 25

Elastic Modulus (GPa) 193 25

Tensile Strength (MPa) 515 25 

Yield Strength (MPa) 205 

Hardness (HRB) 88  25 

Thermal Property 

T (°C)

Thermal Expansion (10-6/ºC) 17.2  0-100

Geometry Connections

• Default Contact Regions• Need for Fixed Constraints– Large Contact to Threads of 2 Long Rods– Base of Arbor to Socket Bolt– Large Contacts to 2 Swivels– Fixed Support

Connections: Large Contact to 1st Rod

Connections: Large Contact to 2nd Rod

Connections: Arbor to Socket Bolt

Connections: Large Contact to 1st Swivel

Connections: Large Contact to 2nd Swivel

Fixed Support

Defined Loads

• Worst Case Scenario– Maximum Pressure

• Uniformly Distributed Force– (4000 psi = 27.579 MPa)– Perpendicular to Large

Contact Faces

Defined Loads (2)

• Ramp Loading of Pressure Forces• Approximation of Quick Turn-On of Pressure

Washer

Defined Loads (3)

Defined Loads (4)

Mesh

• Two Different Sizes Used– Relevance Center• Coarse• Fine

• Why?– To compare accuracy of

displacements and stresses

Mesh (2)

• Types of Elements– SOLID 186• High Order 20-node Brick Elements

– SOLID 187• 10-node Quadratic Tetrahedral (H) Elements

– CONTACT 170/174• Part to Part Interaction for Assemblies• High End Surface to Surface Contact Elements

Coarse Mesh

Coarse Mesh: Holes and Edges

• Projected Higher Stresses– Large Contact Holes– Arbor Base Edges

• Refinement of Mesh– Number of Divisions• 15 Elements per Hole

– Size of Elements• 0.001 m for Edges

Coarse Mesh: Holes and Edges (2)

= Hole Refinement

= Edge Refinement

Coarse Mesh: Number of Divisions

Coarse Mesh: Number of Divisions (2)

Fine Mesh

• Relevance Center: Fine• Refinement of Mesh– Number of Divisions• 30 Elements per Hole

Fine Mesh (2)

Fine Mesh (2)

Coarse vs. Fine Mesh

Analyzing the Results

• Analysis to look at– Total Deformation– Equivalent (von Mises) Stresses• Locate Problem Areas

• Comparison of Problem Areas– Coarse and Fine Mesh– Brick and Tetrahedral Meshes of Large Contacts

Total Deformation

Coarse Mesh

Fine Mesh

Equivalent Stress and Problem Areas

Coarse Mesh

Fine Mesh

Problem Areas

Problem Areas

• Threaded Holes Through Large Contacts• Closer Inspection– Brick Mesh– Tetrahedral Mesh– Equivalent Stress• Yield Strength of 205MPa• Tensile Strength of 515MPa

Tetrahedral Meshed Large ContactEquivalent Stress

Coarse MeshMax Stress = 3,500 MPa

Fine MeshMax Stress = 3,500 MPa

Brick Meshed Large ContactEquivalent Stress

Coarse MeshMax Stress = 1,700 MPa

Fine MeshMax Stress = 2,000 MPa

Summary of Results

• Total Deformation Seemed Acceptable• Equivalent Stresses Highlighted Problems• Problem Areas– Tetrahedral Meshed Large Contact• Coarse and Fine Mesh – Over yield

– Brick Meshed Large Contact• Coarse and Fine Mesh – Over yield

• Design Not Acceptable

Design Suggestions

• Thicken the two connecting rods• Thread size increase• Large Contact thickness increase• Add additional connecting rod

Impact Statement

• High Pressure Water Flow - Successfully clean interior of airfoil - Possibility of injury• Current Design - Inner Rod diameters too small - Further development/analysis on overall fixture• Safety of overall design/operation still a major

concern.

Questions?

References

• Moaveni, Saeed. Finite Element Analysis: Theory and Applications with ANSYS, 3rd Ed., Pearson Prentice Hall, Upper Saddle River, NJ, 2007, 30 Oct 2007.

• Nema, K., Akay, H.U., Ch 13 Three Dimensional Elements, Department of Mechanical Engineering, IUPUI, Indianapolis, IN, 3 March, 2004, 23 Oct 2007.

• http://www.efunda.com/materials/alloys/stainless_steels/ 11/26/07