Thickness effect in crack-tip stress analysis
Thickness effect in crack-tip stress analysis
(OP)
Hi
I am analysing crack-tip to study thickness effect in Elastic Plastic fracture mechanics. Here I have taken two TPB specimen geometry with a/w 0.3 and 0.5 with 10mm and 2.5 mm thickness. I have used 'Tool-Midsurface-Assign thickness and offset' option to specify thickness rather than 'using 'Plane stress/strain thickness=' option in section. I have also given thickness 'from geometry' in 'section assignment'. 4 different input files were created. I used CPS8R plane stress element. but in the result, I get the a/w effect in crack-tip stress-strain analysis and not thickness effect (result in both thicknesses are same). I have attached a pdf with the input file of a/w 0.5 with 2.5 thickness for your reference. I suspect, I have committed some error in my abaqus analysis. Kindly help me in this regards.



I am analysing crack-tip to study thickness effect in Elastic Plastic fracture mechanics. Here I have taken two TPB specimen geometry with a/w 0.3 and 0.5 with 10mm and 2.5 mm thickness. I have used 'Tool-Midsurface-Assign thickness and offset' option to specify thickness rather than 'using 'Plane stress/strain thickness=' option in section. I have also given thickness 'from geometry' in 'section assignment'. 4 different input files were created. I used CPS8R plane stress element. but in the result, I get the a/w effect in crack-tip stress-strain analysis and not thickness effect (result in both thicknesses are same). I have attached a pdf with the input file of a/w 0.5 with 2.5 thickness for your reference. I suspect, I have committed some error in my abaqus analysis. Kindly help me in this regards.








RE: Thickness effect in crack-tip stress analysis
RE: Thickness effect in crack-tip stress analysis
I found ,no significant difference in stress when tried with CPE8R with different thicknesses. After your reply, I have changed my analysis to 3D shell planar with S4R elements with different thicknesses, but still I couldn't get the decreasing crack-tip stresses at mid-plane. The section details are given below. Where I am wrong?? whether, my element selection was wrong??? Other parameters are as same before.
*Element, type=S4R
** Section: Section-2
*Shell Section, elset=Set-9, material=Material-1, poisson=0.29
5., 11
RE: Thickness effect in crack-tip stress analysis
RE: Thickness effect in crack-tip stress analysis
As per your advice, I ran my analysis in 2D solid with CPE8R plane strain analysis on 20,10 and 5 mm thick specimens of a/W0.5. Plane stress/strain thickness in section is also assigned. I expect decreasing S22 at the crack tip (at the same CTOD/CMOD) as thickness decreases, but i got same stress at all the thicknesses. inp files for 10 mm thick is attached herewith. need help please.
RE: Thickness effect in crack-tip stress analysis
RE: Thickness effect in crack-tip stress analysis
RE: Thickness effect in crack-tip stress analysis
RE: Thickness effect in crack-tip stress analysis
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