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wiki:sns:intactgh:resolution_and_convergence [2023/08/15 15:39] – created - external edit 127.0.0.1wiki:sns:intactgh:resolution_and_convergence [2023/09/05 11:14] (current) – michael
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 Resolution is the maximum number of finite element “cells” used to compute an approximate solution of the given analysis problem. These cells create a “solution grid” where only the cells that intersect the solid are included in the actual resolution count. Each finite element cell is a cube with side length equal to the “cell size”. Due to the cubic scaling of resolution w.r.t cell size it is easy to select a cell size that yields an unexpectedly large resolution.  Resolution is the maximum number of finite element “cells” used to compute an approximate solution of the given analysis problem. These cells create a “solution grid” where only the cells that intersect the solid are included in the actual resolution count. Each finite element cell is a cube with side length equal to the “cell size”. Due to the cubic scaling of resolution w.r.t cell size it is easy to select a cell size that yields an unexpectedly large resolution. 
  
-{{ :wiki:sns:intact.gho:cellsizevsresolution.png?500 }}+{{ :wiki:sns:intactgh:cellsizevsresolution.png?500 }}
  
 So why not just always use the maximum resolution? There are at least two important reasons: So why not just always use the maximum resolution? There are at least two important reasons:
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 **To learn more on how to pick the proper resolution for analysis, read this [[wiki:sns:intactgh:select_resolution|document]].** **To learn more on how to pick the proper resolution for analysis, read this [[wiki:sns:intactgh:select_resolution|document]].**
  
-{{ :wiki:sns:intact.gho:resolutiongridgraphic.png?500 }}+{{ :wiki:sns:intactgh:resolutiongridgraphic.png?500 }}
  
 ===== Convergence ===== ===== Convergence =====
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 To establish that the solution converged, solve the same problem a number of times, gradually increasing the resolution, until displacement values stay approximately in the same range. If displacement does not converge, there is no guarantee that the numerical solution is accurate. To establish that the solution converged, solve the same problem a number of times, gradually increasing the resolution, until displacement values stay approximately in the same range. If displacement does not converge, there is no guarantee that the numerical solution is accurate.
  
-{{ :wiki:sns:intact.gho:displacement_convergence.png?500 }}+{{ :wiki:sns:intactgh:displacement_convergence.png?500 }}
  
 If computed displacement values did converge, one can also study convergence of stresses. But it is important to remember that the linear theory of elasticity (used by every structural analysis software, including the present version of Intact.Simulation for Grasshopper) predicts infinite stresses near “wedges,” re-entrant corners, interfaces between different materials, and other singularities. In physical reality, this cannot happen, because the material simply deforms more “plastically” (as opposed to “elastically”). This means that at some points in a model, stresses may never converge – they will just get bigger and bigger as you increase the resolution. The more complex your model is, the more likely you will have some singularities like that. It does make sense to study convergence of stress values at particular locations in the model that are away from singularities. If computed displacement values did converge, one can also study convergence of stresses. But it is important to remember that the linear theory of elasticity (used by every structural analysis software, including the present version of Intact.Simulation for Grasshopper) predicts infinite stresses near “wedges,” re-entrant corners, interfaces between different materials, and other singularities. In physical reality, this cannot happen, because the material simply deforms more “plastically” (as opposed to “elastically”). This means that at some points in a model, stresses may never converge – they will just get bigger and bigger as you increase the resolution. The more complex your model is, the more likely you will have some singularities like that. It does make sense to study convergence of stress values at particular locations in the model that are away from singularities.
wiki/sns/intactgh/resolution_and_convergence.1692135571.txt.gz · Last modified: 2023/08/15 15:39 by 127.0.0.1