hi, I am following your videos, in this particular example(tutorial:7) I got an error " The following features has encountered a problem: - Features: Stationary solver (sol/s1) constraint found for variables in different segregated groups. try to merge the groups. how to resolve it... (I have followed the video pin to pin).
Great set of videos! In this one, at about 9:53, you state that conduction between materials requires definition of contact points. But in Tutorial 6, you modeled the capacitance of a porous material. If you had instead modeled resistance in Tutorial 6, would you have needed a whole bunch of contact points (because there would have been conduction between materials)? Or would that not have mattered simply because the pores were full of air (which is non-conductive)? Or is something else going on? Also, in Tutorial 5, you modeled the resistance of a composite material. Why did you not have to define contact points there? Was definition of contact points required here because the contact points were literally points?
From the Solid Mechanics Physics modeling in the software, defining Contact Pairs are necessary between two boundaries which are being in contact under loading. Otherwise it does not solve the problem. That is why we need to define it in here unlike tutorial 5 where no Solid Mechanics and contact mechanic physics are involved and the geometries are stationary so no need to define contact pair and we only use form union when creating the geometries so the boundaries are shared between two different domains. From the electrical point of view, when two conductors are separated by a non-conductor (e.g., air), the resistance between them is infinite like an open circuit. When the contact is created, the junctions are formed so that charges (electrons) are allowed to flow which creates a non-infinite resistance between top and bottom surfaces in the system based on the definition of Ohmic loss, and the more contact area, the more conductance of charges thus lower resistance. In tutorial 6 we used a different interface with no conductivity involved as we deal with dielectric properties in capacitance modeling. In that case if we use the Electric Current interface, again the problem in tutorial 7 it is different from tutorial 6 problem where an existing solid domain appears between the top and bottom electrode which creates the pathways for electrons (again no contact mechanics involved). Please note that the resistance (and conductance) are both material and geometrical dependent unlike the resistivity (and conductivity) which are materials properties only.
Another question: I don't understand why the deformation and resistance are coupled. In your final solution, at full force, the triangles are bent but they are still touching the top layer at only one point. I was expecting to see them squished. With the result shown, I don't see how the resistance changes at all. And in any case, I don't see how changes in resistance would affect the deformation. The material with the triangles doesn't seem to have any properties that would stiffen (unstiffen) it due to current flowing through it.
Ideally the contact area in the small scale would not remain as a point with larger forces and deformations, maybe not clearly shown here but when making much finer meshes it might be better to notice that. Apart from that, by deforming the solid domain, the geometry of the formed resistance is essentially changing (even small) resulting in the small variation of the resistance.
hello thanks for you effort and your way. when i apply an error appeared which is " Segregated Step 1 Division by zero. - Function: / Failed to evaluate variable. - Variable: comp1.solid.D12 - Defined as: (comp1.solid.E*comp1.solid.nu)/((1+comp1.solid.nu)*(1-(2*comp1.solid.nu))) Failed to evaluate variable. - Variable: comp1.solid.Sl22 - Defined as: (comp1.solid.Fiil22^2)*(comp1.solid.Ji*(((comp1.solid.eel11*comp1.solid.D12)+(comp1.solid.eel22*comp1.solid.D22))+(comp1.solid.eel33*comp1.solid.D23))) Failed to evaluate expression. - Expression: d(((-comp1.solid.Sl11*test(comp1.solid.el11)-2*comp1.solid.Sl12*test(comp1.solid.el12)-2*comp1.solid.Sl13*test(comp1.solid.el13)-comp1.solid.Sl22*test(comp1.solid.el22)-2*comp1.solid.Sl23*test(comp1.solid.el23)-comp1.solid.Sl33*test(comp1.solid.el33))*comp1.solid.d)*(dvol),{test@3}) Failed to evaluate Jacobian of expression. - Expression: ((-comp1.solid.Sl11*test(comp1.solid.el11)-2*comp1.solid.Sl12*test(comp1.solid.el12)-2*comp1.solid.Sl13*test(comp1.solid.el13)-comp1.solid.Sl22*test(comp1.solid.el22)-2*comp1.solid.Sl23*test(comp1.solid.el23)-comp1.solid.Sl33*test(comp1.solid.el33))*comp1.solid.d)*(dvol) " An error occurred when evaluating a variable. The domains in which COMSOL Multiphysics tried to evaluate the variable are indicated. Also, the error message shows the expression that COMSOL Multiphysics was unable to evaluate. Make sure that the variable is available in that part of the model and if so, that you have defined the variable correctly in the indicated domains. i am try to do it again and follow the steps carefully but it don't gets, so what should i do ?
hi, I am following your videos,
in this particular example(tutorial:7) I got an error " The following features has encountered a problem:
- Features: Stationary solver (sol/s1)
constraint found for variables in different segregated groups. try to merge the groups.
how to resolve it... (I have followed the video pin to pin).
Same result here. Version 6.1
@@FM-go5rx same here, have you managed to solve it?
Great set of videos! In this one, at about 9:53, you state that conduction between materials requires definition of contact points. But in Tutorial 6, you modeled the capacitance of a porous material. If you had instead modeled resistance in Tutorial 6, would you have needed a whole bunch of contact points (because there would have been conduction between materials)? Or would that not have mattered simply because the pores were full of air (which is non-conductive)? Or is something else going on? Also, in Tutorial 5, you modeled the resistance of a composite material. Why did you not have to define contact points there? Was definition of contact points required here because the contact points were literally points?
From the Solid Mechanics Physics modeling in the software, defining Contact Pairs are necessary between two boundaries which are being in contact under loading. Otherwise it does not solve the problem. That is why we need to define it in here unlike tutorial 5 where no Solid Mechanics and contact mechanic physics are involved and the geometries are stationary so no need to define contact pair and we only use form union when creating the geometries so the boundaries are shared between two different domains. From the electrical point of view, when two conductors are separated by a non-conductor (e.g., air), the resistance between them is infinite like an open circuit. When the contact is created, the junctions are formed so that charges (electrons) are allowed to flow which creates a non-infinite resistance between top and bottom surfaces in the system based on the definition of Ohmic loss, and the more contact area, the more conductance of charges thus lower resistance. In tutorial 6 we used a different interface with no conductivity involved as we deal with dielectric properties in capacitance modeling. In that case if we use the Electric Current interface, again the problem in tutorial 7 it is different from tutorial 6 problem where an existing solid domain appears between the top and bottom electrode which creates the pathways for electrons (again no contact mechanics involved). Please note that the resistance (and conductance) are both material and geometrical dependent unlike the resistivity (and conductivity) which are materials properties only.
Hi how can i contact you,it would be really helpful as i need an expert to solve my simulation issue
Another question: I don't understand why the deformation and resistance are coupled. In your final solution, at full force, the triangles are bent but they are still touching the top layer at only one point. I was expecting to see them squished. With the result shown, I don't see how the resistance changes at all. And in any case, I don't see how changes in resistance would affect the deformation. The material with the triangles doesn't seem to have any properties that would stiffen (unstiffen) it due to current flowing through it.
Ideally the contact area in the small scale would not remain as a point with larger forces and deformations, maybe not clearly shown here but when making much finer meshes it might be better to notice that. Apart from that, by deforming the solid domain, the geometry of the formed resistance is essentially changing (even small) resulting in the small variation of the resistance.
Can this model be applied for capacitive-based pressure sensor?
hello thanks for you effort and your way. when i apply an error appeared which is " Segregated Step 1
Division by zero.
- Function: /
Failed to evaluate variable.
- Variable: comp1.solid.D12
- Defined as: (comp1.solid.E*comp1.solid.nu)/((1+comp1.solid.nu)*(1-(2*comp1.solid.nu)))
Failed to evaluate variable.
- Variable: comp1.solid.Sl22
- Defined as: (comp1.solid.Fiil22^2)*(comp1.solid.Ji*(((comp1.solid.eel11*comp1.solid.D12)+(comp1.solid.eel22*comp1.solid.D22))+(comp1.solid.eel33*comp1.solid.D23)))
Failed to evaluate expression.
- Expression: d(((-comp1.solid.Sl11*test(comp1.solid.el11)-2*comp1.solid.Sl12*test(comp1.solid.el12)-2*comp1.solid.Sl13*test(comp1.solid.el13)-comp1.solid.Sl22*test(comp1.solid.el22)-2*comp1.solid.Sl23*test(comp1.solid.el23)-comp1.solid.Sl33*test(comp1.solid.el33))*comp1.solid.d)*(dvol),{test@3})
Failed to evaluate Jacobian of expression.
- Expression: ((-comp1.solid.Sl11*test(comp1.solid.el11)-2*comp1.solid.Sl12*test(comp1.solid.el12)-2*comp1.solid.Sl13*test(comp1.solid.el13)-comp1.solid.Sl22*test(comp1.solid.el22)-2*comp1.solid.Sl23*test(comp1.solid.el23)-comp1.solid.Sl33*test(comp1.solid.el33))*comp1.solid.d)*(dvol)
"
An error occurred when evaluating a variable. The domains in which COMSOL Multiphysics tried to evaluate the variable are indicated. Also, the error message shows the expression that COMSOL Multiphysics was unable to evaluate. Make sure that the variable is available in that part of the model and if so, that you have defined the variable correctly in the indicated domains.
i am try to do it again and follow the steps carefully but it don't gets, so what should i do ?
Hi Mohammad, please follow all steps presented in the video very carefully that probably will fix your issue
Could you share more examples?
Thanks for the comment. We will add more example on this topic early November.
@@Teacheetah Thank you so much!Your examples have helped me a lot. Can you add some examples of 3D models?
Thanks for the comment. We are planning to add more videos to our Comsol course. We will consider this topic too.