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ME 450 Group Adrian Conrad Chris Cook Thomas Hylton Nathan Wagers High Pressure Water Fixture Conceptual Design Analysis December 10, 2007
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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.
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Introduction High Pressure Water Fixture designed to flow water through interior of an airfoil to clean out any extra debris.
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Introduction 4,000 psi water flowing into fixture. Stainless Steel fixture material. Arbor adjustability Fixture Dimensions: - Height: 4.5” - Length: 12” - Width: 5”
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Element Types 186 and 187 type elements Used for Curved Surfaces More nodes allows surface conformability 4 Node Tetrahedral Element 10 Node Tetrahedral Element
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Utilized Theory Maximum Displacement – For u, v, & w components Von Mises Stress
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Utilized Theory Contd… Strain Where: And:
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Model Details Pro/E Model – Assembly of 34 Components IGES File Creation – Solid Type
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FEA Tool: ANSYS Workbench Why? – Efficient Meshing Automatic Mesh – Ease of Use for Refinement Large Contact Edges Arbor Bottom Edges
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IGES File Import
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Large Contact Long Rods IGES File Import (2) Arbor Base Side Large Contacts Socket Bolt Swivel Base Top Long Rods Arbor Cap Swivel Case
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Model Details: Material Stainless Steel AISI 304 Mechanical Properties T (°C) Density (×1000 kg/m 3 ) 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
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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
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Connections: Large Contact to 1 st Rod
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Connections: Large Contact to 2 nd Rod
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Connections: Arbor to Socket Bolt
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Connections: Large Contact to 1 st Swivel
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Connections: Large Contact to 2 nd Swivel
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Fixed Support
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Defined Loads Worst Case Scenario – Maximum Pressure Uniformly Distributed Force – (4000 psi = 27.579 MPa) – Perpendicular to Large Contact Faces
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Defined Loads (2) Ramp Loading of Pressure Forces Approximation of Quick Turn-On of Pressure Washer
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Defined Loads (3)
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Defined Loads (4)
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Mesh Two Different Sizes Used – Relevance Center Coarse Fine Why? – To compare accuracy of displacements and stresses
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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
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Coarse Mesh
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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
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Coarse Mesh: Holes and Edges (2) = Hole Refinement = Edge Refinement
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Coarse Mesh: Number of Divisions
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Coarse Mesh: Number of Divisions (2)
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Fine Mesh Relevance Center: Fine Refinement of Mesh – Number of Divisions 30 Elements per Hole
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Fine Mesh (2)
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Coarse vs. Fine Mesh
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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
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Total Deformation Coarse Mesh Fine Mesh
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Equivalent Stress and Problem Areas Coarse Mesh Fine Mesh Problem Areas
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Threaded Holes Through Large Contacts Closer Inspection – Brick Mesh – Tetrahedral Mesh – Equivalent Stress Yield Strength of 205MPa Tensile Strength of 515MPa
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Tetrahedral Meshed Large Contact Equivalent Stress Coarse Mesh Max Stress = 3,500 MPa Fine Mesh Max Stress = 3,500 MPa
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Brick Meshed Large Contact Equivalent Stress Coarse Mesh Max Stress = 1,700 MPa Fine Mesh Max Stress = 2,000 MPa
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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
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Design Suggestions Thicken the two connecting rods Thread size increase Large Contact thickness increase Add additional connecting rod
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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.
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Questions?
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References Moaveni, Saeed. Finite Element Analysis: Theory and Applications with ANSYS, 3 rd 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/stainles s_steels/ 11/26/07 http://www.efunda.com/materials/alloys/stainles s_steels/
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