Hi, can you share where you got the values for the initial yield stress, saturation flow stress, and saturation exponent that you used in this vid? thank you
Unfortunately I don't have the original source from which I extracted the information. But you can look up yield and tensile strength of specific aluminium alloys. if you get an estimate of the linear plastic modulus then you can use a best-fit curve to estimate the saturation exponent.
If you have experimental data for the stress-strain curve you could find a best fit relation. So the values of the saturation exponent and stress would minimise the error from the best-fit curve.
From the physics, insert 'Nonlinear elastic material'. Then choose uniaxial data from the material model, select user defined function and use your interpolation function. solid.eax is the input strain variable.
@@JafScienceFirst of all, thank you. After setting the name of the interpolation function (int2), how do I write an expression in the uniaxial data field? ex) int2[MPa]?
Hi Please I have some questions as: 1- What are the advantages of COMSOL compared to Ansys or Abaqus? 2- Have COMSOL powerful built-in concrete models? 3- Can comsol model and do nonlinear analysis of reinforced concrete walls under cyclic reversible loading? 4- Can comsol capture the PINCHING effect of concrete during cyclic loading of the above case? 5- Can comsol capture the shear reduction strength of concrete during cyclic loading of the above case? 6-Can comsol define the bond slippage between steel bars and concrete automatically by built-in interface? Thanks
Comsol has a simpler interface and a more efficient solver (takes less time to solve using the same resources as ansys). It's especially good with multiphysics applications since you can connect any number of different physics using the same interface (ansys is poor in this aspect). As for concrete models, I've never used them so I don't know but they have a broad library so I'd imagine the stuff you're looking for are included somewhere within the structural analysis module.
If you have experimental data for the stress-strain curve, you can import it into an interpolation function. Under physics, insert "Nonlinear Elastic Material", then select "Uniaxial data" under Material model. Under stress function you need to use your interpolation function and the input will be the strain variable solid.eax
@@JafScience Thank you for your answer, Concerning my case, I have a problem of Four Point Bending of beam. I add the stress-strain curve with the interpolation. I also add Uniaxial compressivre strength for concrete material. I want to know in my case how I can add the load ?.and how solved this problem in the Comsol. I shared with you these images that I applied. if you want, I can send you my model by email. pasteboard.co/K01mMhW.png , pasteboard.co/K01n9t9.png , pasteboard.co/K01oUNR.png
You can add the load as a boundary condition as you have done in those images. I'm not sure which material you are working with. There's only one beam but two materials. If it's concrete then you need to add two curves since concrete is much stronger in compression and does not behave isotropically. The tensile curve would be applicable to one half of the beam (which is under tension) and the compression curve would be applicable for the other half (which is under compression).
My problem is the same with the Concrete_beam model from the Comsol library, except in my case I use the four-point bending. for the second material it is Steel structure which linked to the 5 bars added in the concrete. Regarding the Stress-strain component that i addedas an interpolation, hw can i apply it in the calculations?, I don't yet understand how to use it
In solid mechanics, add a "nonlinear elastic domain", choose "uniaxial" model, and your stress function will be int1(solid.eax). int1 is your interpolation function.
in my case, instead of a predefined hardening model, if I want to incorporate a user-defined hardening equation. is it possible? if yes what is the proces?
Thank you for the tutorial. If I need to apply prescribed displacement of 20mm/min instead of force how can I do it. The material is polypropylene with Young's modulus of 709 MPa and yield stress of 31 MPa and Poissons ratio 0.4. can I model it using Ramberg-osgood material model
You can define 'prescribed velocity' on a boundary. The default units are m/s so you should convert your velocity accordingly. Alternatively, you could define a ramp function with slope equal to 20mm/min and then use it in ''prescribed displacement' boundary condition. The first option is easier. The Ramberg-Osgood model is suitable for metals and materials that show smooth transition from elastic to plastic zones. Polypropylene is different so you need to choose a model that resembles its stress-strain curve. If you have experimental data then you could define that.
same model replicated * found error .* - Feature: Time-Dependent Solver 1 (sol1/t1) Failed to compute elastoplastic strain variables. Time-dependent solver interrupted. Not all time steps returned.
@@JafScience When the external force is removed again after applying the external force, the deformation should remain, but it returns to its original shape like an elastic material. Of course, the uniaxial data includes the plastic region
@@JafScience I am trying to simulate a biomechanical model for a seated human body.. I defin all the fixed joints and rigid domains and parametres.. but when i want to simulate the stress and strain I face some problems in comsol..if you can provide me with your contact to present or send the file to you.. i'll appreciaite that a lot
Sir, is it possible to generate stress strain curve for a model solved in stationary solution? I need help please, I've performed tensile test on a hollow PVC pipe, now my task is to design a comsol project for the practical I performed. Your guidence will be highly appreciated sir
Yes you can use a parametric study to change the applied load but the unloading segment of the stress-strain curve cannot be generated in a stationary study.
Clarification (05:55): the saturation flow stress is the difference between the ultimate tensile stress and the initial yield stress.
One of the best of best video about stress strain modeling.
Thank you sir.
Awesome!!! THX a lot! You helped me with problem that I was struggling for half of the year🤩
Very nice and complete video 👍
Hi, can you share where you got the values for the initial yield stress, saturation flow stress, and saturation exponent that you used in this vid? thank you
Unfortunately I don't have the original source from which I extracted the information. But you can look up yield and tensile strength of specific aluminium alloys. if you get an estimate of the linear plastic modulus then you can use a best-fit curve to estimate the saturation exponent.
Okay, thank you@@JafScience
How do I find the saturation exponent and linear hardening coefficient?
If you have experimental data for the stress-strain curve you could find a best fit relation. So the values of the saturation exponent and stress would minimise the error from the best-fit curve.
How do I apply the stress-strain curve table values after inputting them into the interpolation function?
From the physics, insert 'Nonlinear elastic material'. Then choose uniaxial data from the material model, select user defined function and use your interpolation function. solid.eax is the input strain variable.
@@JafScienceFirst of all, thank you. After setting the name of the interpolation function (int2), how do I write an expression in the uniaxial data field?
ex) int2[MPa]?
int2(solid.eax)
@@JafScience wow! Thank you very much!
@@JafScience If you analyze using the uniaxiald data, you cannot express the plastic deformation. Is there a way to add plastic behavior?
Hi
Please I have some questions as:
1- What are the advantages of COMSOL compared to Ansys or Abaqus?
2- Have COMSOL powerful built-in concrete models?
3- Can comsol model and do nonlinear analysis of reinforced concrete walls under cyclic reversible loading?
4- Can comsol capture the PINCHING effect of concrete during cyclic loading of the above case?
5- Can comsol capture the shear reduction strength of concrete during cyclic loading of the above case?
6-Can comsol define the bond slippage between steel bars and concrete automatically by built-in interface?
Thanks
Comsol has a simpler interface and a more efficient solver (takes less time to solve using the same resources as ansys). It's especially good with multiphysics applications since you can connect any number of different physics using the same interface (ansys is poor in this aspect).
As for concrete models, I've never used them so I don't know but they have a broad library so I'd imagine the stuff you're looking for are included somewhere within the structural analysis module.
Thanks for this tutorial, regarding the case where I have experimental data, how can I add comsol?
If you have experimental data for the stress-strain curve, you can import it into an interpolation function. Under physics, insert "Nonlinear Elastic Material", then select "Uniaxial data" under Material model. Under stress function you need to use your interpolation function and the input will be the strain variable solid.eax
@@JafScience Thank you for your answer, Concerning my case, I have a problem of Four Point Bending of beam.
I add the stress-strain curve with the interpolation. I also add Uniaxial compressivre strength for concrete material. I want to know in my case how I can add the load ?.and how solved this problem in the Comsol.
I shared with you these images that I applied. if you want, I can send you my model by email.
pasteboard.co/K01mMhW.png , pasteboard.co/K01n9t9.png , pasteboard.co/K01oUNR.png
You can add the load as a boundary condition as you have done in those images. I'm not sure which material you are working with. There's only one beam but two materials. If it's concrete then you need to add two curves since concrete is much stronger in compression and does not behave isotropically. The tensile curve would be applicable to one half of the beam (which is under tension) and the compression curve would be applicable for the other half (which is under compression).
My problem is the same with the Concrete_beam model from the Comsol library, except in my case I use the four-point bending. for the second material it is Steel structure which linked to the 5 bars added in the concrete. Regarding the Stress-strain component that i addedas an interpolation, hw can i apply it in the calculations?, I don't yet understand how to use it
In solid mechanics, add a "nonlinear elastic domain", choose "uniaxial" model, and your stress function will be int1(solid.eax). int1 is your interpolation function.
Could you please tell me, which COMSOL Modul is needed for this Simulation? The nonlinear structural materials module?
Yes, it's called non-linear structural mechanics but the features are added within several interfaces (solid mechanics, beam, etc).
in my case, instead of a predefined hardening model, if I want to incorporate a user-defined hardening equation. is it possible? if yes what is the proces?
Select hardening function from the hardening model and type your own function which represents the stress in the plastic region.
Thank you for the tutorial. If I need to apply prescribed displacement of 20mm/min instead of force how can I do it. The material is polypropylene with Young's modulus of 709 MPa and yield stress of 31 MPa and Poissons ratio 0.4. can I model it using Ramberg-osgood material model
You can define 'prescribed velocity' on a boundary. The default units are m/s so you should convert your velocity accordingly. Alternatively, you could define a ramp function with slope equal to 20mm/min and then use it in ''prescribed displacement' boundary condition. The first option is easier.
The Ramberg-Osgood model is suitable for metals and materials that show smooth transition from elastic to plastic zones. Polypropylene is different so you need to choose a model that resembles its stress-strain curve. If you have experimental data then you could define that.
@@JafScience Hi, then which model do you recommend to use for polypropylene?
same model replicated * found error .*
- Feature: Time-Dependent Solver 1 (sol1/t1)
Failed to compute elastoplastic strain variables.
Time-dependent solver interrupted.
Not all time steps returned.
If you analyze using the uniaxiald data, you cannot express the plastic deformation. Is there a way to add plastic behavior?
If the plastic region of the stress-strain curve is part of the uniaxial data then you don't need to do something else.
@@JafScience When the external force is removed again after applying the external force, the deformation should remain, but it returns to its original shape like an elastic material. Of course, the uniaxial data includes the plastic region
Hi sir, can i ask you please about somethings, i want to undertand them anw i can pay for them... thank you
What are the questions you want to ask?
@@JafScience I am trying to simulate a biomechanical model for a seated human body.. I defin all the fixed joints and rigid domains and parametres.. but when i want to simulate the stress and strain I face some problems in comsol..if you can provide me with your contact to present or send the file to you.. i'll appreciaite that a lot
Can you send me a message on my twitter account?
@@JafScience yes sir send your account
Why setting 26 as value for saturation exponent?
I got the value from a journal paper.
Is that a value usable in general?
It's for a specific grade of aluminium so it can't be used for any material.
@@JafScience What if this value is not available?
@@fernandoesm5838 You'll need to use another model, or you can estimate it from the closest data available.
Sir ,For modeling a hollow cylinder, is it must to use 3d geometry? Or we can use 2d symmetry,?
You can use 2D axisymmetric model.
Thank you sir
Sir, is it possible to generate stress strain curve for a model solved in stationary solution? I need help please, I've performed tensile test on a hollow PVC pipe, now my task is to design a comsol project for the practical I performed.
Your guidence will be highly appreciated sir
Yes you can use a parametric study to change the applied load but the unloading segment of the stress-strain curve cannot be generated in a stationary study.
Is it possible to model the elasticity of a nylon notched tube using similar logic?
Yes, you need to to have the stress-strain relationship of the material and then use the appropriate model.
thank you.