Guidelines for Obtaining Contact Convergence

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Typical Turbomachinery Applications • 2D axisymmetric engine assembly models. – Small Models, many (100+) contact pairs • 3D component assembly models – Large Models, few (1-10) contact pairs © 2008 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary
Newton Raphson Method [K] [U] = [F a ] For contact problems, [K] is a nonlinear function of [U] Nonlinear equations written as: [K it ] [ΔU i ] = [F a ] – [F i nr ] Displacement change between iterations: {U i+1 } = {U i } + {ΔU i } [K it ] = Jacobian matrix (tangent matrix). i = current equilibrium iteration number. [F a ] = Vector of applied loads. [F i nr ] = Vector of restoring loads (opposes the internal nodal loads). [R] = [F a ] – [F i nr ] Residual, or out-of-balance <strong>for</strong>ce vector. [R] < 0.001 [F a ] <strong>Convergence</strong> criteria (Residual must be less than 0.1% of the applied load. © 2008 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary
Page 1 and 2: 2008 International ANSYS Conference
Page 3: Debugging Contact Analyses • Cont
Page 7 and 8: Understanding Solution Output Under
Page 9 and 10: Typical Solution Output (continued)
Page 11 and 12: Interpreting CNCHECK Summary Summar
Page 13 and 14: What can go wrong? Example 1 ALL CU
Page 15 and 16: What can go wrong? Example 2 2D axi
Page 17 and 18: What can go wrong? Example 2 Contac
Page 19 and 20: What can go wrong? Example 3 Gear t
Page 21 and 22: What can go wrong? Example 3 Initia
Page 23 and 24: What can go wrong? Example 3 Better
Page 25 and 26: Contact Tools CNCHECK command: List
Page 27 and 28: Failure to Detect Contact Resulting
Page 29: Contact Trouble Shooting Guide •

Guidelines for Obtaining Contact Convergence

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