Date post: | 15-Jan-2016 |
Category: |
Documents |
Upload: | elias-cogbill |
View: | 222 times |
Download: | 0 times |
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