While attempting to solve a linear elasticity problem (including a stress solver) I am running into the following error:
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ERROR:: IterSolve: Numerical Error: System diverged over maximum tolerance.
Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO
STOP 1The full output of the solver is as follows:
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ELMER SOLVER (v 9.0) STARTED AT: 2023/08/29 19:08:23
ParCommInit: Initialize #PEs: 1
MAIN:
MAIN: =============================================================
MAIN: ElmerSolver finite element software, Welcome!
MAIN: This program is free software licensed under (L)GPL
MAIN: Copyright 1st April 1995 - , CSC - IT Center for Science Ltd.
MAIN: Webpage http://www.csc.fi/elmer, Email elmeradm@csc.fi
MAIN: Version: 9.0 (Rev: Release, Compiled: 2023-07-13)
MAIN: Running one task without MPI parallelization.
MAIN: Running with just one thread per task.
MAIN: Lua interpreter linked in.
MAIN: =============================================================
MAIN:
MAIN:
MAIN: -------------------------------------
MAIN: Reading Model: mid_load.sif
LoadInputFile: Scanning input file: mid_load.sif
LoadInputFile: Scanning only size info
LoadInputFile: First time visiting
LoadInputFile: Reading base load of sif file
LoadInputFile: Loading input file: mid_load.sif
LoadInputFile: Reading base load of sif file
CheckKeyword: Unlisted keyword: [force 2 normalize by area] in section: [boundary condition 1]
CheckKeyword: Unlisted keyword: [force 1 normalize by area] in section: [boundary condition 2]
CheckKeyword: Unlisted keyword: [force 2 normalize by area] in section: [boundary condition 3]
CheckKeyword: Unlisted keyword: [force 2 normalize by area] in section: [boundary condition 4]
CheckKeyword: Unlisted keyword: [force 1 normalize by area] in section: [boundary condition 4]
LoadInputFile: Number of BCs: 4
LoadInputFile: Number of Body Forces: 0
LoadInputFile: Number of Initial Conditions: 0
LoadInputFile: Number of Materials: 1
LoadInputFile: Number of Equations: 1
LoadInputFile: Number of Solvers: 2
LoadInputFile: Number of Bodies: 1
ListTagKeywords: Setting weight for keywords!
ListTagKeywords: Adding dist tag to "force 2"
ListTagKeywords: Tagged 1 parameters in list
ListTagKeywords: Adding dist tag to "force 1"
ListTagKeywords: Tagged 1 parameters in list
ListTagKeywords: Adding dist tag to "force 2"
ListTagKeywords: Tagged 1 parameters in list
ListTagKeywords: Adding dist tag to "force 2"
ListTagKeywords: Adding dist tag to "force 1"
ListTagKeywords: Tagged 2 parameters in list
ListTagKeywords: Tagged 5 parameters with suffix: normalize by area
ListTagKeywords: Setting weight for keywords!
ListTagKeywords: No parameters width suffix: normalize by volume
ElmerAsciiMesh: Base mesh name: ./.
ERROR:: ReadBoundaryFile: 0 BOUNDARY PARENT out of range: 697 174
LoadMesh: Elapsed REAL time: 0.0080 (s)
MAIN: -------------------------------------
AddVtuOutputSolverHack: Adding ResultOutputSolver to write VTU output in file: case
StressSolve_init: --------------------------------------------------
StressSolve_init: Solving displacements from linear elasticity model
StressSolve_init: --------------------------------------------------
OptimizeBandwidth: Initial bandwidth for linear elasticity: 48
OptimizeBandwidth: Optimized bandwidth for linear elasticity: 58
OptimizeBandwidth: Bandwidth optimization rejected, using original ordering.
MAIN: Number of timesteps to be saved: 1
MAIN:
MAIN: -------------------------------------
MAIN: Steady state iteration: 1
MAIN: -------------------------------------
MAIN:
BC weight: 1 0.65600000000000036
BC weight: 2 0.32000000000000023
BC weight: 3 6.4000000000000001E-002
BC weight: 4 9.5999999999999974E-002
BF weight: 1 0.0000000000000000
Body weight: 1 0.40396800000003263
Mat weight: 1 0.40396800000003263
StressSolve:
StressSolve: --------------------------------------------------
StressSolve: Solving displacements from linear elasticity model
StressSolve: --------------------------------------------------
StressSolve: Displacement iteration: 1
StressSolve: Starting assembly...
StressSolve: Assembly:
10 0.1503E+00
20 0.7380E-01
30 0.4330E-01
40 0.2514E-01
50 0.2228E-01
60 0.2001E-01
70 0.1609E-01
80 0.1651E-01
90 0.1625E-01
100 0.1638E-01
110 0.1662E-01
120 0.1728E-01
130 0.2651E-01
140 0.2226E-01
150 0.1783E-01
160 0.1971E-01
170 0.1700E-01
180 0.2901E-01
190 0.4050E-01
200 0.2721E-01
210 0.3620E-01
212 NaN
ERROR:: IterSolve: Numerical Error: System diverged over maximum tolerance.
Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO
STOP 1This is the contents of my .sif file:
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Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 5
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Simulation Type = Steady state
Steady State Max Iterations = 1
Output Intervals(1) = 1
Solver Input File = case.sif
Post File = case.vtu
End
Constants
Gravity(4) = 0 -1 0 9.82
Stefan Boltzmann = 5.670374419e-08
Permittivity of Vacuum = 8.85418781e-12
Permeability of Vacuum = 1.25663706e-6
Boltzmann Constant = 1.380649e-23
Unit Charge = 1.6021766e-19
End
Body 1
Target Bodies(1) = 1
Name = "Body 1"
Equation = 1
Material = 1
End
Solver 1
Equation = Linear elasticity
Procedure = "StressSolve" "StressSolver"
Exec Solver = Always
Stabilize = True
Optimize Bandwidth = True
Steady State Convergence Tolerance = 1.0e-5
Nonlinear System Convergence Tolerance = 1.0e-7
Nonlinear System Max Iterations = 20
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e-3
Nonlinear System Relaxation Factor = 1
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStab
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e-10
BiCGstabl polynomial degree = 2
Linear System Preconditioning = ILU0
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = False
Linear System Residual Output = 10
Linear System Precondition Recompute = 1
End
Solver 2
Equation = Result Output VTK
Single Precision = True
Binary Output = True
Procedure = "ResultOutputSolve" "ResultOutputSolver"
Vector Field 1 = Stresses
Output Format = vtk
Scalar Field 1 = Displacement
Output File Name = mid_load_
End
Equation 1
Name = "Linear elasticity"
Calculate Stresses = True
Active Solvers(1) = 1
End
Material 1
Name = "Bone"
Poisson ratio = 0.4
Youngs modulus = 10e9
Density = 1895
End
Boundary Condition 1
Target Boundaries(41) = 18 19 20 21 22 23 24 25 26 37 38 39 40 41 42 43 44 45 46 47 48 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312
Name = "force_muscle"
Force 1 = 0
Force 3 = 0
Force 2 = -68e3
Force 2 Normalize by Area = Logical True
End
Boundary Condition 2
Target Boundaries(20) = 1 2 3 4 5 6 7 8 9 10 11 12 283 284 285 286 287 288 289 290
Name = "constraint_occipital"
Displacement 3 = 0
Displacement 2 = 0
Displacement 1 = 0
Force 1 = 55e3
Force 1 Normalize by Area = Logical True
End
Boundary Condition 3
Target Boundaries(4) = 174 175 176 177
Name = "force_bite"
Force 2 = 35488
Force 2 Normalize by Area = Logical True
End
Boundary Condition 4
Target Boundaries(6) = 249 250 251 252 253 254
Name = "force_joint"
Force 2 = 32513
Force 2 Normalize by Area = Logical True
Force 1 = -55e3
Force 1 Normalize by Area = Logical True
End
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Force 2 Normalize by Area = Logical TrueAlso, an alternative .sif file, with similar external forces but applied at different boundaries, also runs fine on this model (even if normalization by area for the third boundary condition is left active). I have attached this .sif file for your reference.
I will be glad to supply additional information if needed.
Any assistance you can provide would be greatly appreciated.
Cheers,
Max