Thankyou sir, I am modelling screw connection in back to back built up column with connector function, what type of connector should i be using ,i have to give non linear stiffness. Can you tell me what all should i be doing to correctly model it .😊
@@adhil.a3619 you should use Translator connector and define a stiffness curve in the local X direction. I teach how to do it in the following video: ua-cam.com/video/mWoyzkKFsdI/v-deo.htmlsi=iN8GR4t8oWWKgN61 The link above goes to a series of 2 videos. It is in the second video that I teach about translator connector for bolt pre tension. The problem is that I guess you want to model the bolt itself with the translator, right? If that is the case, the strategy is a little different. I will soon create a video about it.
Thank you for this incredible guide. I have a complex situation where i need to activate the elasticity after the distance is under a certain point. For example the distance is 100 at first step, and i need to simulate a rope-like behavior when the distance becomes 50 in step-2 to prevent anymore tension above 50. I wrote 0 F for 0 displacement and 999999 F for 50 displacement. But how do i stabilize the system until that point in first step? Can i decrease the F above the 50 displacement back to 0?
@@mangalustas015 looks nice a cool application. I need to understand a little more about your model. Maybe you could use a stopper, which is one technique I didn’t talk about in this tutorial. Another way is to do it the way you already did, that is, to put a high stiffness to simulate a stopper. Anyways, I need more info about your model to be able yo guide you. Can you send me an email? It’d be helpful if you send me the .inp file as well. My email: renato.carvalho@learnfea.com
Hi Renato, thank you very much for the clear explanation! I wanted to ask, is there a way to only activate the spring on Step 2? Say for instance that you apply a load history in Step 1 (let us assume the necessary modifications to this point problem to make sense) and then replace it for this pre-strained spring. Is this possible, or when I do a connector I need to carry it along across all the simulation? Thanks again for the video!
@@matheusdelorenzo3633 Ty Matheus. I didn’t really understand your application, but there is one simple way to have a connector only working later on your analysis. If you know how much variation in length this connector is going to be subjected in the first step, you can define 0 stiffness for this variation. Then, after that you can define it with stiffness. You should input a nonlinear curve. Example: if you want it to have 10 mm of compressive and tractive displacement without force, and then after that you want to have a stiffness of 10 N/mm, the the first point of the curve should be like -20 mm versus -10 N, then -10 mm 0 N, then 0 mm and 0 N, then 10 mm and 0 N, then 20 mm and 10 N. Maybe it’s a little confusing explaining like that. The other solution is to use *MODEL CHANGE keyword. Research about. Use ChatGPT to help you. Send an email to me with more details if you couldn’t solve it yet. My email: renato.carvalho@learnfea.com
@eng.renatocarvalho Hi Renato, thank you very much for the quick response! Unfortunatelly, to my particular case, I don't know a priori the variation in length to my connector, so I cannot conveniently set up stiffness. I need it to have 0 stiffness everytime it reaches a certain step (Step-2) in my sims, which can have any arbitrary lenght. Thanks for the second tip! I tried *MODEL CHANGE and although it worked for contact-like interactions, it did not work (when I tried, at least) for connectors in particular. I am still not sure why. After a lot of trial and error, what really worked for me was using UAMP (or VUAMP) subroutine, getting the position of that arbitrary point of interest from a sensor and then setting it up to zero by subtracting it by a state variable (which is nothing more than the arbitrary position itself) when we begin Step-2 (thus setting stiffness to 0 regarless of variation in length). Then we can write any function with respect with this relative displacement we would like, which solves the problem (for now!)
Great question! You can use for example *CONNECTOR FAILURE command. Want to know how to use? Search on Google "Abaqus Keyword". Click on the first link. Search for *CONNECTOR FAILURE in this manual. There, you'll have instruction on how to define it. You can always ask ChatGPT to help you. Train ChatGPT with this part of Abaqus User's Guide and ask him to write you whole command as you need. Let me know if it worked!
@@tonywilliams5340 you will have to define a force versus displacement curve in which for positive displacement (traction) there will be a specific stiffness, and for negative displacement (compression) there’s no stiffness. I do this to model the suspension jounce bumper, but in this case it’s the opposite (there’s only stiffness for compression)
@@eng.renatocarvalho Will it give it the rigidity of a taught wire, similar to the rigid axial connector? How do I make it 0, do I just make it really low (like F = -0.01, u = 10)?
@@tonywilliams5340 in the case of zero stiffness for compression, you should create to points in the stiffness curve like this: for displacement equals 0, force equals 0; for displacement equals -100, force equals 0. If you have a deflection greater than -100, then Abaqus will extrapolate using the inclination defined by the last 2 points. Therefore it will keep force equals 0.
Hello sir, I am trying to use the connector axial nonlinear damping, defining force & velocity, to simulate a viscous damper behavior under simple cyclic motion (displacement over time) using sin wave, i have displacement versus force data which have been collected from the lab, i found the velocity for each time increment, my question is, for nonlinear force & velocity data, do i need to define positive and negative forces and velocities, or only positive data are enough to describe the behavior in both directions?, viscous damper should have the same behavior in both directions, and also Nice video, thanks for your efforts, i have been waiting for the nonlinear damping video you talked about 😅.
You should define the negative part of the curve as well because if not, Abaqus will extrapolate linearly or as a constant level of force dependying on the option you choose for extrapolation. Let me know if it worked. You can contact me through email as well if you'd like to (my email: renato.carvalho@learnfea.com)
Hello sir, could you please suggest a literature/ video tutorial regarding Non Absorbing Boundary condition (spring and dashpot type) in Soil Structure Interaction analysis. I am working on Dam-Reservoir-Foundation analysis and trying to disseminate seismic waves traveling in a finite foundation medium...
Thankyou sir,
I am modelling screw connection in back to back built up column with connector function, what type of connector should i be using ,i have to give non linear stiffness.
Can you tell me what all should i be doing to correctly model it .😊
@@adhil.a3619 you should use Translator connector and define a stiffness curve in the local X direction. I teach how to do it in the following video: ua-cam.com/video/mWoyzkKFsdI/v-deo.htmlsi=iN8GR4t8oWWKgN61
The link above goes to a series of 2 videos. It is in the second video that I teach about translator connector for bolt pre tension.
The problem is that I guess you want to model the bolt itself with the translator, right? If that is the case, the strategy is a little different. I will soon create a video about it.
Your guide was very useful for me, thank you.
Thank you for this incredible guide. I have a complex situation where i need to activate the elasticity after the distance is under a certain point. For example the distance is 100 at first step, and i need to simulate a rope-like behavior when the distance becomes 50 in step-2 to prevent anymore tension above 50. I wrote 0 F for 0 displacement and 999999 F for 50 displacement. But how do i stabilize the system until that point in first step? Can i decrease the F above the 50 displacement back to 0?
@@mangalustas015 looks nice a cool application. I need to understand a little more about your model. Maybe you could use a stopper, which is one technique I didn’t talk about in this tutorial. Another way is to do it the way you already did, that is, to put a high stiffness to simulate a stopper. Anyways, I need more info about your model to be able yo guide you. Can you send me an email? It’d be helpful if you send me the .inp file as well. My email: renato.carvalho@learnfea.com
Hi Renato, thank you very much for the clear explanation!
I wanted to ask, is there a way to only activate the spring on Step 2? Say for instance that you apply a load history in Step 1 (let us assume the necessary modifications to this point problem to make sense) and then replace it for this pre-strained spring.
Is this possible, or when I do a connector I need to carry it along across all the simulation?
Thanks again for the video!
@@matheusdelorenzo3633 Ty Matheus. I didn’t really understand your application, but there is one simple way to have a connector only working later on your analysis. If you know how much variation in length this connector is going to be subjected in the first step, you can define 0 stiffness for this variation. Then, after that you can define it with stiffness. You should input a nonlinear curve. Example: if you want it to have 10 mm of compressive and tractive displacement without force, and then after that you want to have a stiffness of 10 N/mm, the the first point of the curve should be like -20 mm versus -10 N, then -10 mm 0 N, then 0 mm and 0 N, then 10 mm and 0 N, then 20 mm and 10 N. Maybe it’s a little confusing explaining like that. The other solution is to use *MODEL CHANGE keyword. Research about. Use ChatGPT to help you. Send an email to me with more details if you couldn’t solve it yet. My email: renato.carvalho@learnfea.com
@eng.renatocarvalho Hi Renato, thank you very much for the quick response!
Unfortunatelly, to my particular case, I don't know a priori the variation in length to my connector, so I cannot conveniently set up stiffness. I need it to have 0 stiffness everytime it reaches a certain step (Step-2) in my sims, which can have any arbitrary lenght.
Thanks for the second tip! I tried *MODEL CHANGE and although it worked for contact-like interactions, it did not work (when I tried, at least) for connectors in particular. I am still not sure why.
After a lot of trial and error, what really worked for me was using UAMP (or VUAMP) subroutine, getting the position of that arbitrary point of interest from a sensor and then setting it up to zero by subtracting it by a state variable (which is nothing more than the arbitrary position itself) when we begin Step-2 (thus setting stiffness to 0 regarless of variation in length). Then we can write any function with respect with this relative displacement we would like, which solves the problem (for now!)
@@matheusdelorenzo3633 Interesting solution Matheus. I've never used UAMP subroutine. I'll get to know about it. Thanks!
how to include damage or failure? i able to plot nonlinear elasticity curve but not enough for my study, how to assign plasticity?
Great question! You can use for example *CONNECTOR FAILURE command. Want to know how to use? Search on Google "Abaqus Keyword". Click on the first link. Search for *CONNECTOR FAILURE in this manual. There, you'll have instruction on how to define it. You can always ask ChatGPT to help you. Train ChatGPT with this part of Abaqus User's Guide and ask him to write you whole command as you need. Let me know if it worked!
How would you use this to simulate a cable or rope? Where you get it to only have tension and no compression
@@tonywilliams5340 you will have to define a force versus displacement curve in which for positive displacement (traction) there will be a specific stiffness, and for negative displacement (compression) there’s no stiffness. I do this to model the suspension jounce bumper, but in this case it’s the opposite (there’s only stiffness for compression)
@@eng.renatocarvalho Will it give it the rigidity of a taught wire, similar to the rigid axial connector? How do I make it 0, do I just make it really low (like F = -0.01, u = 10)?
@@tonywilliams5340 in the case of zero stiffness for compression, you should create to points in the stiffness curve like this: for displacement equals 0, force equals 0; for displacement equals -100, force equals 0. If you have a deflection greater than -100, then Abaqus will extrapolate using the inclination defined by the last 2 points. Therefore it will keep force equals 0.
Hello sir, I am trying to use the connector axial nonlinear damping, defining force & velocity, to simulate a viscous damper behavior under simple cyclic motion (displacement over time) using sin wave, i have displacement versus force data which have been collected from the lab, i found the velocity for each time increment, my question is, for nonlinear force & velocity data, do i need to define positive and negative forces and velocities, or only positive data are enough to describe the behavior in both directions?, viscous damper should have the same behavior in both directions, and also Nice video, thanks for your efforts, i have been waiting for the nonlinear damping video you talked about 😅.
You should define the negative part of the curve as well because if not, Abaqus will extrapolate linearly or as a constant level of force dependying on the option you choose for extrapolation. Let me know if it worked. You can contact me through email as well if you'd like to (my email: renato.carvalho@learnfea.com)
@@eng.renatocarvalho Wow, I didn't expect a reply in such short time 😊 Got it, I will try it out and let you know through your email, thanks again 🙏
Hello sir, could you please suggest a literature/ video tutorial regarding Non Absorbing Boundary condition (spring and dashpot type) in Soil Structure Interaction analysis.
I am working on Dam-Reservoir-Foundation analysis and trying to disseminate seismic waves traveling in a finite foundation medium...
Hello Ammarvanank, I don’t have any on top of my head. This is not an area (Soil Structure) that I’ve worked before.