Hello,
I am trying to solve a simple beam problem and getting some strange results. Stresses seem to be very high in comparison to Ansys. I am sure I am missing something here so I will appreciate if someone could check the SIF file for me. I am using nodal forces and units are US custom units. Since this is an elasticity problem only material properties needed are youngs modulus and poisson ratio. I used carbon steel and modified only these two.
Thanks a lot for your help...
semo
SIF file
Header
CHECK KEYWORDS Warn
Mesh DB "." "."
Include Path ""
Results Directory ""
End
Simulation
Max Output Level = 4
Coordinate System = Cartesian
Coordinate Mapping(3) = 1 2 3
Simulation Type = Steady state
Steady State Max Iterations = 1
Output Intervals = 1
Timestepping Method = BDF
BDF Order = 1
Solver Input File = case.sif
Post File = case.ep
End
Constants
Gravity(4) = 0 -1 0 9.82
Stefan Boltzmann = 5.67e-08
Permittivity of Vacuum = 8.8542e-12
Boltzmann Constant = 1.3807e-23
Unit Charge = 1.602e-19
End
Body 1
Target Bodies(1) = 158
Name = "Body 1"
Equation = 1
Material = 1
End
Solver 1
Equation = Linear elasticity
Procedure = "StressSolve" "StressSolver"
Variable = -dofs 3 Displacement
Exec Solver = Always
Stabilize = True
Bubbles = False
Lumped Mass Matrix = False
Optimize Bandwidth = True
Steady State Convergence Tolerance = 1.0e-5
Nonlinear System Convergence Tolerance = 1.0e-8
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-8
Linear System Preconditioning = ILU0
Linear System ILUT Tolerance = 1.0e-3
Linear System Abort Not Converged = False
Linear System Residual Output = 1
Linear System Precondition Recompute = 1
End
Equation 1
Name = "elasticity"
Flow Solution Name = String Flow Solution
Convection = Computed
Plane Stress = True
Calculate Stresses = True
Active Solvers(1) = 1
End
Material 1
Name = "Steel (carbon - generic)"
Heat Conductivity = 44.8
Youngs modulus = 29.0e6
Mesh Poisson ratio = 0.285
Heat Capacity = 1265.0
Density = 7850.0
Poisson ratio = 0.285
Heat Conductivity = 44.8
Sound speed = 5100.0
Heat expansion Coefficient = 13.8e-6
End
Boundary Condition 1
Target Nodes(1) =Integer 28
Force 2 = 12000
End
Boundary Condition 2
Target Nodes(1) =Integer 31
Force 2 = 12000
End
Boundary Condition 3
Target Nodes(1) =Integer 3
Displacement 2 = 0
Displacement 1 = 0
End
Boundary Condition 4
Target Nodes(1) =Integer 23
Displacement 2 = 0
Displacement 1 = 0
End
Boundary Condition 5
Target Nodes(1) =Integer 197
Displacement 2 = 0
Displacement 1 = 0
End
Nodal Forces - Elasticity
Re: Nodal Forces - Elasticity
Hi Semo,
could you attach your mesh, and some description of the expected result?
RGDS, Juha
PS. this is probably not supposed to work at all with the current code, but i don't really see why not;
thus i'll have look.
could you attach your mesh, and some description of the expected result?
RGDS, Juha
PS. this is probably not supposed to work at all with the current code, but i don't really see why not;
thus i'll have look.
Re: Nodal Forces - Elasticity
Hi,
... OTOH with the current code your case should work out , if you replace "Force 2" with
"Displacement 2 Load" (?), if your primary variable name is 'Displacement'...
Regards, Juha
... OTOH with the current code your case should work out , if you replace "Force 2" with
"Displacement 2 Load" (?), if your primary variable name is 'Displacement'...
Regards, Juha
Re: Nodal Forces - Elasticity
Hello,
Thanks for the responses, sorry for late thank you response. I finally got it to match with Ansys results. I used a very simple geometry, a 2D model, simply supported 2" by 36" beam with a 24000lbf force acting in the middle. Now I have a more fundamental question rather than a Elmer question. Why the maximum bending stress I got does not match with Mc/I ?
With a simple calculation (assuming the beam is 1" wide) I got 162ksi from Mc/I whereas Elmer/Ansys show around 328ksi for the maximum stresses. FEA assumes plane stress which translates into very wide beam assumption. Does it make any sense to compare these two?
Thanks again for all the input and help...
Thanks for the responses, sorry for late thank you response. I finally got it to match with Ansys results. I used a very simple geometry, a 2D model, simply supported 2" by 36" beam with a 24000lbf force acting in the middle. Now I have a more fundamental question rather than a Elmer question. Why the maximum bending stress I got does not match with Mc/I ?
With a simple calculation (assuming the beam is 1" wide) I got 162ksi from Mc/I whereas Elmer/Ansys show around 328ksi for the maximum stresses. FEA assumes plane stress which translates into very wide beam assumption. Does it make any sense to compare these two?
Thanks again for all the input and help...