Dear all
I am doing triaxial test simulation, but I am facing some problem.
1. First, I applied six servo controlled wall using command to execute a confining pressure on a cube soil specimen, with the following command.
fix twall_servo all mesh/surface/stress/servo file meshes/sample_1/topwall.stl type 2 com 0.025 0.025 1.0 ctrlPV force axis 0.0 0.0 -1.0 target_val 100 vel_max 0.001
fix bwall_servo all mesh/surface/stress/servo file meshes/sample_1/bottomwall.stl type 2 com 0.025 0.025 0.0 ctrlPV force axis 0.0 0.0 1.0 target_val 100 vel_max 0.001
fix wall1_servo all mesh/surface/stress/servo file meshes/sample_1/sidewall1.stl type 2 com 0.05 0.025 0.06 ctrlPV force axis -1.0 0.0 0.0 target_val 200 vel_max 0.001
fix wall2_servo all mesh/surface/stress/servo file meshes/sample_1/sidewall2.stl type 2 com 0.025 0.0 0.06 ctrlPV force axis 0.0 1.0 0.0 target_val 200 vel_max 0.001
fix wall3_servo all mesh/surface/stress/servo file meshes/sample_1/sidewall3.stl type 2 com 0.0 0.025 0.06 ctrlPV force axis 1.0 0.0 0.0 target_val 200 vel_max 0.001
fix wall4_servo all mesh/surface/stress/servo file meshes/sample_1/sidewall4.stl type 2 com 0.025 0.05 0.06 ctrlPV force axis 0.0 -1.0 0.0 target_val 200 vel_max 0.001
2. After applying confining pressure I am modifying the servo command for top and bottom plate to apply additional axial pressure, with the following command
fix_modify twall_servo servo/target_val 250
fix_modify bwall_servo servo/target_val 250
But I am facing the following problem
1. I am not able to achieve constant wall force. The forces on the wall are constantly decreasing.
2. I am unable to obtain constant confining pressure
southeast1012 | Thu, 11/14/2019 - 13:02
Hi Rahul
In my opinion, after consolidation, your bottom wall and topwall need to change to strain_controlled walls. and to get constant confining pressure you can try to decrease the vel_max.
Zhao
Rachel | Wed, 11/20/2019 - 03:54
Hi there,
Hi there,
In my mind, I think you should use the target pressure instead of target force for the consolidation process, because the contact area at each face will keep changing with the loading process. All you need is to keep modifying the target force value by calculating it using Force=pressure*Area. I hope this would help.
Rachel
wangxiukai | Sat, 04/24/2021 - 16:09
Dear Rachel,
Dear Rachel,
I am a newer of liggghts and want to consult some questions.
How to calculating the area? Do you have a scripyt about the servo prolem?
Thank you a lot.
Wang xiukai
ANITA A | Thu, 05/12/2022 - 08:16
Script request
Could you please share your triaxial test scripts with me?
My email is 102204001@smail.iitpkd.ac.in
Syed.hussaine | Sat, 11/25/2023 - 09:05
Compression test Input script
Hello everyone. I am a new user of Liggghts. Can anyone here provide me a input script of compression test.
Hassnain.ah@gmail.com is my email.
Thanks.