Learning Forum

[MichArcher]

Dear community,

I have been trying this problem from every angle, but no luck.

It is a simple transient thermal-structural problem with a rotating metallic wheel. The thermal coupling was defined using the following command under the geometry:

et, matid, 227, 11

A revolute ground-to-body joint was placed on the inner ring as you can see.

The initial temperature of the tire is 200 C. The rotational velocity is 5 rad/sec (ramped). There is a convection surface on the upper face of the tire. Units are mm, N, C.

The following command was put under the settings:

tref,22

IC,TIRE,TEMP,200  !INITIAL TEMP

SF,CONVRING,CONV,0.000025,22

Allsel

[MichArcher]

                      S O L U T I O N  O P T I O N Sn n  PROBLEM DIMENSIONALITY. . . . . . . . . . . . .3-D                 n  DEGREES OF FREEDOM. . . . . . UX  UY  UZ  ROTX ROTY ROTZ TEMPn  ANALYSIS TYPE . . . . . . . . . . . . . . . . .TRANSIENT           n     SOLUTION METHOD. . . . . . . . . . . . . . .FULL                n  OFFSET TEMPERATURE FROM ABSOLUTE ZERO . . . . . 273.15   n  NONLINEAR GEOMETRIC EFFECTS . . . . . . . . . .ONn  EQUATION SOLVER OPTION. . . . . . . . . . . . .SPARSE            n  NEWTON-RAPHSON OPTION . . . . . . . . . . . . .PROGRAM CHOSEN  n  GLOBALLY ASSEMBLED MATRIX . . . . . . . . . . .UNSYMMETRICn n *** WARNING ***                        CP =      3.922  TIME= 16:51:24n Material number 4 (used by element 36591) should normally have at least n one MP or one TB type command associated with it. Output of energy by n material may not be available.                                         n n *** WARNING ***                        CP =      3.922  TIME= 16:51:24n No constraints have been defined using the D command.                  n n *** NOTE ***                           CP =      4.297  TIME= 16:51:24n The step data was checked and warning messages were found.             n Please review output or errors file (                                 n C:\Downloads\Simulation\_ProjectScratch\ScrE0EE\file0.err ) for these  n warning messages.                                                      n n *** NOTE ***                           CP =      4.297  TIME= 16:51:24n This nonlinear analysis defaults to using the full Newton-Raphson      n solution procedure. This can be modified using the NROPT command.     n n *** NOTE ***                           CP =      4.312  TIME= 16:51:24n Internal nodes from 45834 to 45837 are created.                        n 1 internal nodes are used for handling degrees of freedom on pilot     n nodes of rigid target surfaces.                                        n 3 internal nodes are used for non-contact elements with mixed          n formulation.                                                           n n *** NOTE ***                           CP =      4.328  TIME= 16:51:24n Internal nodes from 45834 to 45837 are created.                        n 1 internal nodes are used for handling degrees of freedom on pilot     n nodes of rigid target surfaces.                                        n 3 internal nodes are used for non-contact elements with mixed          n formulation.                                                           n n *** WARNING ***                        CP =      4.359  TIME= 16:51:24n Contact element 36594 is missing DOF TEMP (and possibly others) of     n underlying base element 1745. Similar mismatches may exist elsewhere, n but checking for this is discontinued.                                 n n *** NOTE ***                           CP =      4.375  TIME= 16:51:24n Rigid-constraint surface identified by real constant set 2 and contact n element type 2 has been set up. The degrees of freedom of the rigid   n surface are driven by the pilot node 45833 which connects to other     n element 36591. Internal MPC will be built.                            n The used degrees of freedom set is UX  UY  UZ  ROTX ROTY ROTZn ****************************************n n n n n *** NOTE ***                           CP =      4.391  TIME= 16:51:24n Internal nodes from 45834 to 45837 are created.                        n 1 internal nodes are used for handling degrees of freedom on pilot     n nodes of rigid target surfaces.                                        n 3 internal nodes are used for non-contact elements with mixed          n formulation.                                                           n n n n

[MichArcher]

D I S T R I B U T E D D O M A I N D E C O M P O S E Rn n ...Number of elements: 5900n ...Number of nodes: 10379n ...Decompose to 4 CPU domainsn ...Element load balance ratio = 1.002n n n L O A D S T E P O P T I O N Sn n LOAD STEP NUMBER. . . . . . . . . . . . . . . . 1n TIME AT END OF THE LOAD STEP. . . . . . . . . . 1.0000 n AUTOMATIC TIME STEPPING . . . . . . . . . . . . ONn STARTING TIME STEP SIZE. . . . . . . . . . . 0.10000E-02n MINIMUM TIME STEP SIZE . . . . . . . . . . . 0.10000E-05n MAXIMUM TIME STEP SIZE . . . . . . . . . . . 0.10000 n MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS. . . . 15n STEP CHANGE BOUNDARY CONDITIONS . . . . . . . . YESn STRESS-STIFFENING . . . . . . . . . . . . . . . ONn TRANSIENT (INERTIA) EFFECTSn STRUCTURAL DOFS. . . . . . . . . . . . . . . ONn THERMAL DOFS . . . . . . . . . . . . . . . . ONn TRANSIENT INTEGRATION PARAMETERSn GAMMA. . . . . . . . . . . . . . . . . . . . 0.10000 n ALPHA. . . . . . . . . . . . . . . . . . . . 0.30250 n DELTA. . . . . . . . . . . . . . . . . . . . 0.60000 n USING HHT TIME INTEGRATIONn ALPHAF . . . . . . . . . . . . . . . . . . . 0.10000 n ALPHAM . . . . . . . . . . . . . . . . . . . 0.0000 n THETA. . . . . . . . . . . . . . . . . . . . 0.50000 n OSCILLATION LIMIT CRITERION. . . . . . . . . 0.50000 n TOLERANCE. . . . . . . . . . . . . . . . . . 0.20000 n TERMINATE ANALYSIS IF NOT CONVERGED . . . . . .YES (EXIT) n CONVERGENCE CONTROLS. . . . . . . . . . . . . .USE DEFAULTSn PRINT OUTPUT CONTROLS . . . . . . . . . . . . .NO PRINTOUTn DATABASE OUTPUT CONTROLSn ITEM FREQUENCY COMPONENTn ALL NONE n NSOL ALL n RSOL ALL n EANG ALL n ETMP ALL n VENG ALL n NLOA ALL n STRS ALL n SRFS ALL n BKST ALL n EPEL ALL n EPPL ALL n CONT ALL n NLDA ALL n V ALL n A ALL n MISC ALL n n n SOLUTION MONITORING INFO IS WRITTEN TO FILE= file.mntr n MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS HAS BEEN MODIFIED n TO BE, NEQIT = 25, BY SOLUTION CONTROL LOGIC. n n n *** WARNING *** CP = 7.719 TIME= 16:51:28n For element 36591 the element connectivity is 0 and 45833. The node n which is identified as a 0 will be a grounded node. n n n *********** PRECISE MASS SUMMARY ***********n n TOTAL RIGID BODY MASS MATRIX ABOUT ORIGINn Translational mass | Coupled translational/rotational massn 0.23675E-03 0.0000 0.0000 | 0.0000 0.46066E-09 -0.94700E-03n 0.0000 0.23675E-03 0.0000 | -0.46066E-09 0.0000 -0.38338E-11n 0.0000 0.0000 0.23675E-03 | 0.94700E-03 0.38338E-11 0.0000 n ------------------------------------------ | ------------------------------------------n | Rotational mass (inertia)n | 0.12343 0.28734E-10 0.25045E-09n | 0.28734E-10 0.23675 -0.20504E-08n | 0.25045E-09 -0.20504E-08 0.12343 n n TOTAL MASS = 0.23675E-03n The mass principal axes coincide with the global Cartesian axesn n CENTER OF MASS (X,Y,Z)= -0.16193E-07 4.0000 0.19458E-05n n TOTAL INERTIA ABOUT CENTER OF MASSn 0.11964 0.13399E-10 0.25045E-09n 0.13399E-10 0.23675 -0.20773E-09n 0.25045E-09 -0.20773E-09 0.11964 n The inertia principal axes coincide with the global Cartesian axesn n n *** MASS SUMMARY BY ELEMENT TYPE ***n n TYPE MASSn 1 0.236750E-03n n Range of element maximum matrix coefficients in global coordinatesn Maximum = 2458977.83 at element 3029. n Minimum = 187491.304 at element 1662. n n *** ELEMENT MATRIX FORMULATION TIMESn TYPE NUMBER ENAME TOTAL CP AVE CPn n 1 5514 SOLID227 7.219 0.001309n 2 384 CONTA174 0.078 0.000203n 3 1 TARGE170 0.000 0.000000n 4 1 MPC184 0.000 0.000000n Time at end of element matrix formulation CP = 8.546875. n n ALL CURRENT ANSYS DATA WRITTEN TO FILE NAME= file.rdbn FOR POSSIBLE RESUME FROM THIS POINTn CONSTRAINT CONDITIONS ARE NOT SATISFIED FOR 1 JOINT ELEMENTS WITH LAG MULT OPTIONn FORCE CONVERGENCE VALUE = 0.7000E-09 CRITERION= 0.5102E-04n HT FLOW CONVERGENCE VALUE= 0.3663 CRITERION= 0.2310E-03n n DISTRIBUTED SPARSE MATRIX DIRECT SOLVER.n Number of equations = 38816, Maximum wavefront = 3052n n Local memory allocated for solver = 108.619 MBn Local memory required for in-core solution = 89.216 MBn Local memory required for out-of-core solution = 39.582 MBn n Total memory allocated for solver = 412.769 MBn Total memory required for in-core solution = 337.197 MBn Total memory required for out-of-core solution = 147.893 MBn n *** NOTE *** CP = 10.641 TIME= 16:51:32n The Distributed Sparse Matrix Solver is currently running in the n in-core memory mode. This memory mode uses the most amount of memory n in order to avoid using the hard drive as much as possible, which most n often results in the fastest solution time. This mode is recommended n if enough physical memory is present to accommodate all of the solver n data. n

[MichArcher]

*** WARNING *** CP = 10.641 TIME= 16:51:32n Pivoting has been activated for the Distributed Sparse Matrix Solver . n The memory required may greatly exceed the predicted amount. In that n event, use the DSPOPTION command to change the memory mode and/or n memory size used by the Distributed Sparse Matrix Solver. n n *** NOTE *** CP = 10.641 TIME= 16:51:32n The system matrix is unsymmetric. n curEqn= 9809 totEqn= 9809 Job CP sec= 14.000n Factor Done= 100% Factor Wall sec= 3.625 rate= 843.2 Mflopsn Distributed sparse solver maximum pivot= 3564021.59 at node 6318 UX. n Distributed sparse solver minimum pivot= 219.947471 at node 1608 UY. n Distributed sparse solver minimum pivot in absolute value= 219.947471 n at node 1608 UY. n DISP CONVERGENCE VALUE = 879.9 CRITERION= 44.89 n EQUIL ITER 1 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= 879.9 n n *** ERROR *** CP = 15.000 TIME= 16:51:38n Some of the element based thermal loads may be inappropriate. Check n applied element loads carefully. Ensure that film coefficients and n bulk temperatures are always positive. n n *** ERROR *** CP = 15.000 TIME= 16:51:38n Element 4481 (type = 1, SOLID227) (and maybe other elements) has become n highly distorted. Excessive distortion of elements is usually a n symptom indicating the need for corrective action elsewhere. Try n ramping the load up instead of step applying the load (KBC,1). You n may need to improve your mesh to obtain elements with better aspect n ratios. Also consider the behavior of materials, contact pairs, n and/or constraint equations. Please rule out other root causes of n this failure before attempting rezoning or nonlinear adaptive n solutions. If this message appears in the first iteration of first n substep, be sure to run shape checking of elements. n *** LOAD STEP 1 SUBSTEP 1 NOT COMPLETED. CUM ITER = 2n *** BEGIN BISECTION NUMBER 1 NEW TIME INCREMENT= 0.35000E-03n n n *** WARNING *** CP = 17.484 TIME= 16:51:41n For element 36591 the element connectivity is 0 and 45833. The node n which is identified as a 0 will be a grounded node. n n Range of element maximum matrix coefficients in global coordinatesn Maximum = 2458977.83 at element 3029. n Minimum = 187491.304 at element 1662. n CONSTRAINT CONDITIONS ARE NOT SATISFIED FOR 1 JOINT ELEMENTS WITH LAG MULT OPTIONn FORCE CONVERGENCE VALUE = 0.7000E-09 CRITERION= 0.5102E-04n HT FLOW CONVERGENCE VALUE= 0.3663 CRITERION= 0.2310E-03n n DISTRIBUTED SPARSE MATRIX DIRECT SOLVER.n Number of equations = 38816, Maximum wavefront = 3052n n Local memory allocated for solver = 108.619 MBn Local memory required for in-core solution = 89.216 MBn Local memory required for out-of-core solution = 39.582 MBn n Total memory allocated for solver = 412.769 MBn Total memory required for in-core solution = 337.197 MBn Total memory required for out-of-core solution = 147.893 MBn n *** NOTE *** CP = 21.266 TIME= 16:51:47n The Distributed Sparse Matrix Solver is currently running in the n in-core memory mode. This memory mode uses the most amount of memory n in order to avoid using the hard drive as much as possible, which most n often results in the fastest solution time. This mode is recommended n if enough physical memory is present to accommodate all of the solver n data. n n *** WARNING *** CP = 21.281 TIME= 16:51:47n Pivoting has been activated for the Distributed Sparse Matrix Solver . n The memory required may greatly exceed the predicted amount. In that n event, use the DSPOPTION command to change the memory mode and/or n memory size used by the Distributed Sparse Matrix Solver. n n *** NOTE *** CP = 21.281 TIME= 16:51:47n The system matrix is unsymmetric. n curEqn= 9809 totEqn= 9809 Job CP sec= 23.297n Factor Done= 100% Factor Wall sec= 1.211 rate= 2525.2 Mflopsn Distributed sparse solver maximum pivot= 3564022.13 at node 6318 UX. n Distributed sparse solver minimum pivot= 586.641726 at node 117 TEMP. n Distributed sparse solver minimum pivot in absolute value= 586.641726 n at node 117 TEMP. n

[MichArcher]

@peteroznewman n