Stress values are more compared to experimental results and cracks are not formed on concrete for DOUBLE PUNCH TEST simulation in abaqus software

[Shreyas M]

I have modelled Double punch test (Indirect tension test) in abaqus software.
Concrete cylinder-150X150mm
Steel cylinder punches-38.1mm dia and 25.4mm height
Material properties-CDP model for concrete
Steel-mass density,elastic and plastic properties.
Static general step with applying load from 5kn to 110kn monotonically i.e,by defining amplitude
0 0.045
1 1
There are two problems I am facing:-
1.Concrete is a brittle material but after analysis completes cracks are not depicted it shows more plastic character i.e displacement in U2 direction is 30mm.
2.After analysis maximum stress is 60Mpa but concrete grade is 20Mpa.There is a large difference in stress values.

Please tell me how to rectify these two problems??

 

[FEA way]

1.Concrete is a brittle material but after analysis completes cracks are not depicted

Check the documentation chapter Concrete Damaged Plasticity, paragraph Visualization of “Crack Directions”.

2.After analysis maximum stress is 60Mpa but concrete grade is 20Mpa.

What are your CDP model parameters ? Are you checking stresses at the nodes or at the integration points ?

 

[Shreyas M]

Thank you for your reply,

Check the documentation chapter Concrete Damaged Plasticity, paragraph Visualization of “Crack Directions”.


What are your CDP model parameters ? Are you checking stresses at the nodes or at the integration points ?

I was seeing the compression stress in the wrong direction i.e. S22 (direction of apllication of load).But S33 direction the compressive stress value is around 20N/mm2.
But for my project i require TENSILE STRESS values.After job completion the results ( tensile stress ) increase upto a step and then decrease.I am applying monotonic loads of 5kn,10kn till 110kn so the tensile stress values must increase only.I am performing NON-LINEAR STATIC GENERAL analysis.I have attached excel where it consists of M20 grade concrete CDP properties which i have applied in the model,experimendal and numerical results.
1.How to get tensile stress in abaqus?Is there other methods to calculate tensile stress in abaqus?
2.There is a large difference in experimental results and numerical results how to rectify it? The results are attached in the excel file in SHEET 2.