Dear there,
I am currently working on the FSI simulation in LS-DYNA using ALE method. I need to simulate the structure in wind tunnel inflow conditions. Currently, I use the ELFORM=11, AET=4 in *SECTION command to define the inflow Part of the air volume. The inflow parameters are defined by the *EOS of the inflow Part of the air. There are mainly two parameters in *EOS related to the inflow energy or pressure conditions, E0 and V0. I don’t know how to relate the constant inflow velocity, such as 6m/s, with the setting in the model.
Many thanks for your support and help.
Hello everyone,
I am trying to re-do an implicit analysis I read in a paper. The author recommends "force the contacts" on the initial time step. I am using MORTAR contacts, by the way. Would you happen to know what to do to force the contacts?
Thanks a lot for your time!
Regards,
Nicolas
Hello,
I have a Johnson Cook Model which has the function to transfer the visoplastic work to heat. Currently, I only want to see the temper due to the viscosity effect from Johnson Cook model. Also, I want to set initial temperature for my part. I want to ignore the heat transfer effect and only want to see the current temperature(initial temperature + temperature by viscosity)
1: To initialize the initial temperature, do I only need to use the Initial_temperatue_set keyword by creating a node-set that includes the nodes of the whole part?
2: Would you let me know what i need to change from my database settings for example database_extent_binary? I think I need to give NEIPH as 14. Do I need to add the control solution and thermal solver?
3: How can I check the temperature contour result in LS Prepost?
Thank you so much!
Best,
Teng
Hi,
We have some issues with running the LS-DYNA solver on our new computer (The license works on the old computer that ran the LS-DYNA solver before, but it is not working on our new computer).
The problem is that the license was successfully imported into our new computer and the server status is 'running', see the following pictures.
However, when I ran the solver, there was an error that said 'License Problem: Local License: / Error Bad License Keys'. Do you know what the problem is and how do I solve the problem?
Thank you,
Jackie
Hello all!
I am currently developing a wrist model. Following other authors modeling techniques I plan to perform a static simulation. I am new with LS Dyna so I would appreciate some suggestions and general guidance on how to do this.
I previously worked with Abaqus (standard which uses an implicit solver) in which I had the option to enforce a static case by using a keyword and then define a "dummy time" for the load to be applied. I guess the time wasn't really important there because it was a static case.
Within LS Dyna, however, I am not entirely sure what I should do. I am aware that LS Dyna uses an explicit solver by default. I noticed that the results change considerably depending on the time I choose to simulate in *CONTROL_TERMINATION and the curve load defined in *DEFINE_CURVE (a ramp curve together with *LOAD_NODE_SET). I am not sure if this is right so I started exploring the implicit solver since I saw that I can use a static option. So my questions are:
Thanks,
Andres
Hello,
I have a 5 layered model with different materials. All layers should be bonded. I read, that when using shell elements, there should be a sufficient gap between shell and solid to consider the shell thickness (but I could not find how close "sufficient" is). In my model, all Shells have a thickness of 1 mm. I also read, that the algorithm searches for connecting nodes 1/2 of the Shell thickness in normal direction appart from the midsurface line. So I left a gap of 0.5 mm to the respective tied surface. I also set SAST and SBST to -1 mm in order to control the thickness (-0.5 mm did not work). But when running the simulation, I get an error as well as in the message file it reads: "Warning 40538 (SOL+538) Slave node is not constrained no segment was found in bucket sort." In the picture you can see on the left side the mesh on top (no overlapping elements) and the LS Dyna view at the bottom and right the solution after calculation -> the nodes are not TIED together
However, when leaving no gap between Shell elements and the corresponding tied surface, there is no warning message and no error occurs:
This is the contact definition for the first case (gap between Shell and Error/Warning messages):
How should the contact be defined correctly? Is case B (no gap) correct or how can I define the shell thickness for case A in order to tie the nodes together?
Thank you for your support and best wishes
I am trying to model uniaxial compression test of cylindrical specimen using SPG method in LS-Dyna R13.1 in Workbench. I use MAT_024 to define yield stress and MAT_ADD_GISSMO with very small strain to failure (LCSDG) to model "brittle" fracture. IN SECTION_SOLID_SPG I set IDAM = "Programm Controlled" and Self-Contact Indicator (ISC) equal to YES (1). So I hoped that destroyed particles will interact with each other even after specimen crushed.
But when the specimen was crushed the two halves started to move towards each other and I see the penetration of the material (see figures). Therefore the particles don't interact with each other.
Could someone explain why is that so and how can I fix this?
Maybe I have to define glocal contact in the whole model?
I have a small question (may be stupid😂). I am modeling material MAT_024 with a yield stress equal to 5.5 MPa. I want to simulate material brittle fracture using the SPG method and I tried two methods for the definition of material failure criterion:
Thank you in advance!
Hello! I am trying to use GISSMO model with Smooth Particle Galerkin method in Ansys Workbench 2023R1 and want to clarify some points:
Thank you in advance!
How can one fringe the radiative flux coming from a *BOUNDARY_RADIATION_SET?
How can one fringe the radiative flux coming from a *BOUNDARY_RADIATION_SET?
Is there a way to change *ELEMENT_SOLID to *ELEMENT_TSHELL using LS-PrePost? I'd like to pick all elements in a part and make the change.
Within LS-PrePost, whenever I animate results, the fringe results do not update continuously while the animation is running. Stopping the animation at any time step and reselecting the desired fringe result will display it, but restarting the animation again erases the fringe plot and the animation resumes without any fringe data presented.
Is there a setting within LSPP to display fringe results during animations?
Is this supported? If so, is it limited to a simple, smart, and/or full restarts?
I have 4 layers of TSHELLS. They are bonded using *TIED_SURFACE_TO_SURFACE_OFFSET.
Duing deformation the layers are coming apart. I am not using a tiebreak contact so I expected them to stay bonded for all time.
I also have *ERODING_SINGLE_SURFACE defined on these layers since I want elements to be deleted. Are these two contact defintions conflicting? If so, how can I tie the layers and also have them erode?
I'm using LS-Dyna in Workbench. I want to find the area-weighted average maximum principal logarithmic strain but I can't see the option for any form of strain in the results tab of workbench.
Hello,everybody,
Default CSCM parameters did not account for kinematic hardening, according to its User Manual. That is to say, NH=1 and CH=0. Recently, I read the FHWA-HRT-05-063 Evaluation of LS-DYNA Concrete Material Model 159, and it says that by taking kinematic hardening into consideration, pre-peak nonlinearity of concrete stress-strain can be achieved, as shown in the fig.1 below. But the Evaluation did not provide specific procedure for determining the two parameters NH and CH, it only says that 0.7Keyword file of the single element simulation
Thanks for your attention.
Hello i'm a master student developing user material.
i'm wondering that how can i define user- derfined viscosity in mat_sph_viscous subroutine in package..
1) Is it possible to link my umat41v with subroutine f3dm9sph_userdefin?
I want to define the material that is solid when elastic and fluid when after yielding
2) In subroutine f3dm9sph_userdefin, is the xmu is the variable to define??
i can't understand that there's no example in the package...
I really appreciate your help...
please help me
Does anyone know of any methods to decrease model run time when using an ALE mesh? I am modelling a fluid-structure interaction problem and am facing very high run times for a relatively simple model. The model consists of a rigid wave maker, water composed of ALE NULL material, air composed of ALE VACUUM material, and a steel column modeled with shell elements and a PLASTIC_KINEMATIC material.
If I have the column set as a rigid material, the total model run time is 10 minutes, however as soon as I change it to a plastic_kinematic material the run time increases to 13.5 hours using just 800 shell elements to model the column.
In Explicit Dynamics, when determining the force components through the import option (Figure 1), which kind of forces can be imported as an XML file and applied to the geometry? (I mean variable with time or variable with coordinates). Is it possible to convert an Excel file containing force values in different coordinates (Figure 2) to XML and import it?
Since the SPG option was added to the Section object in the Workbench version of LS-Dyna is it possible somehow to display particles using the ANSYS interface?
I know about the LS-PrePost, but I want to implement whole my simulation using ANSYS Workbench. I made a simulation of a uniaxial stress test using SPG (Section -> SPG) but when I try to look at the results I see only finite elements (basic mesh).
Also, I want to know where the bonds between particles were broken (failure of the material). How can I do this?
Hello,
I'm modeling a tension specimen under displacement control by applying prescribed displacement to the node set, while from the output data, the motion of the node set is not moving as I prescribed. I'm using solid element -1. I wonder if anyone faced this kind of problem before?
Thanks,
Min-Chun
Regarding the user defined material, in the manual *Module can be used now to include the USDMAT is the standard LS-Dyna runs.
Thanks!
Hello forum,
I have seen and read many examples of ALE, but they all are FSI problems... I have two metals impacting at high velocities and want both materials to be ALE since both are deforming heavily i.e., I don't think Lagrange In Solid constraint is appropriate here.
Can anyone help me setup an ALE simulation that accomplishes this?
Thanks,
Peter Yip
Dear there,
I am currently working on the FSI simulation in LS-DYNA using ALE method. I need to simulate the structure in wind tunnel inflow conditions. Currently, I use the ELFORM=11, AET=4 in *SECTION command to define the inflow Part of the air volume. The inflow parameters are defined by the *EOS of the inflow Part of the air. There are mainly two parameters in *EOS related to the inflow energy or pressure conditions, E0 and V0. I don’t know how to relate the constant inflow velocity, such as 6m/s, with the setting in the model.
Many thanks for your support and help.
Hello everyone,
I am trying to re-do an implicit analysis I read in a paper. The author recommends "force the contacts" on the initial time step. I am using MORTAR contacts, by the way. Would you happen to know what to do to force the contacts?
Thanks a lot for your time!
Regards,
Nicolas
Hello,
I have a Johnson Cook Model which has the function to transfer the visoplastic work to heat. Currently, I only want to see the temper due to the viscosity effect from Johnson Cook model. Also, I want to set initial temperature for my part. I want to ignore the heat transfer effect and only want to see the current temperature(initial temperature + temperature by viscosity)
1: To initialize the initial temperature, do I only need to use the Initial_temperatue_set keyword by creating a node-set that includes the nodes of the whole part?
2: Would you let me know what i need to change from my database settings for example database_extent_binary? I think I need to give NEIPH as 14. Do I need to add the control solution and thermal solver?
3: How can I check the temperature contour result in LS Prepost?
Thank you so much!
Best,
Teng
Hi,
We have some issues with running the LS-DYNA solver on our new computer (The license works on the old computer that ran the LS-DYNA solver before, but it is not working on our new computer).
The problem is that the license was successfully imported into our new computer and the server status is 'running', see the following pictures.
However, when I ran the solver, there was an error that said 'License Problem: Local License: / Error Bad License Keys'. Do you know what the problem is and how do I solve the problem?
Thank you,
Jackie
Hello all!
I am currently developing a wrist model. Following other authors modeling techniques I plan to perform a static simulation. I am new with LS Dyna so I would appreciate some suggestions and general guidance on how to do this.
I previously worked with Abaqus (standard which uses an implicit solver) in which I had the option to enforce a static case by using a keyword and then define a "dummy time" for the load to be applied. I guess the time wasn't really important there because it was a static case.
Within LS Dyna, however, I am not entirely sure what I should do. I am aware that LS Dyna uses an explicit solver by default. I noticed that the results change considerably depending on the time I choose to simulate in *CONTROL_TERMINATION and the curve load defined in *DEFINE_CURVE (a ramp curve together with *LOAD_NODE_SET). I am not sure if this is right so I started exploring the implicit solver since I saw that I can use a static option. So my questions are:
Thanks,
Andres
Hello,
I have a 5 layered model with different materials. All layers should be bonded. I read, that when using shell elements, there should be a sufficient gap between shell and solid to consider the shell thickness (but I could not find how close "sufficient" is). In my model, all Shells have a thickness of 1 mm. I also read, that the algorithm searches for connecting nodes 1/2 of the Shell thickness in normal direction appart from the midsurface line. So I left a gap of 0.5 mm to the respective tied surface. I also set SAST and SBST to -1 mm in order to control the thickness (-0.5 mm did not work). But when running the simulation, I get an error as well as in the message file it reads: "Warning 40538 (SOL+538) Slave node is not constrained no segment was found in bucket sort." In the picture you can see on the left side the mesh on top (no overlapping elements) and the LS Dyna view at the bottom and right the solution after calculation -> the nodes are not TIED together
However, when leaving no gap between Shell elements and the corresponding tied surface, there is no warning message and no error occurs:
This is the contact definition for the first case (gap between Shell and Error/Warning messages):
How should the contact be defined correctly? Is case B (no gap) correct or how can I define the shell thickness for case A in order to tie the nodes together?
Thank you for your support and best wishes
I am trying to model uniaxial compression test of cylindrical specimen using SPG method in LS-Dyna R13.1 in Workbench. I use MAT_024 to define yield stress and MAT_ADD_GISSMO with very small strain to failure (LCSDG) to model "brittle" fracture. IN SECTION_SOLID_SPG I set IDAM = "Programm Controlled" and Self-Contact Indicator (ISC) equal to YES (1). So I hoped that destroyed particles will interact with each other even after specimen crushed.
But when the specimen was crushed the two halves started to move towards each other and I see the penetration of the material (see figures). Therefore the particles don't interact with each other.
Could someone explain why is that so and how can I fix this?
Maybe I have to define glocal contact in the whole model?
I have a small question (may be stupid😂). I am modeling material MAT_024 with a yield stress equal to 5.5 MPa. I want to simulate material brittle fracture using the SPG method and I tried two methods for the definition of material failure criterion:
Thank you in advance!
Hello! I am trying to use GISSMO model with Smooth Particle Galerkin method in Ansys Workbench 2023R1 and want to clarify some points:
Thank you in advance!
How can one fringe the radiative flux coming from a *BOUNDARY_RADIATION_SET?
How can one fringe the radiative flux coming from a *BOUNDARY_RADIATION_SET?
Is there a way to change *ELEMENT_SOLID to *ELEMENT_TSHELL using LS-PrePost? I'd like to pick all elements in a part and make the change.
Within LS-PrePost, whenever I animate results, the fringe results do not update continuously while the animation is running. Stopping the animation at any time step and reselecting the desired fringe result will display it, but restarting the animation again erases the fringe plot and the animation resumes without any fringe data presented.
Is there a setting within LSPP to display fringe results during animations?
I have 4 layers of TSHELLS. They are bonded using *TIED_SURFACE_TO_SURFACE_OFFSET.
Duing deformation the layers are coming apart. I am not using a tiebreak contact so I expected them to stay bonded for all time.
I also have *ERODING_SINGLE_SURFACE defined on these layers since I want elements to be deleted. Are these two contact defintions conflicting? If so, how can I tie the layers and also have them erode?
I'm using LS-Dyna in Workbench. I want to find the area-weighted average maximum principal logarithmic strain but I can't see the option for any form of strain in the results tab of workbench.
Hello,everybody,
Default CSCM parameters did not account for kinematic hardening, according to its User Manual. That is to say, NH=1 and CH=0. Recently, I read the FHWA-HRT-05-063 Evaluation of LS-DYNA Concrete Material Model 159, and it says that by taking kinematic hardening into consideration, pre-peak nonlinearity of concrete stress-strain can be achieved, as shown in the fig.1 below. But the Evaluation did not provide specific procedure for determining the two parameters NH and CH, it only says that 0.7Keyword file of the single element simulation
Thanks for your attention.
Hello i'm a master student developing user material.
i'm wondering that how can i define user- derfined viscosity in mat_sph_viscous subroutine in package..
1) Is it possible to link my umat41v with subroutine f3dm9sph_userdefin?
I want to define the material that is solid when elastic and fluid when after yielding
2) In subroutine f3dm9sph_userdefin, is the xmu is the variable to define??
i can't understand that there's no example in the package...
I really appreciate your help...
please help me
Does anyone know of any methods to decrease model run time when using an ALE mesh? I am modelling a fluid-structure interaction problem and am facing very high run times for a relatively simple model. The model consists of a rigid wave maker, water composed of ALE NULL material, air composed of ALE VACUUM material, and a steel column modeled with shell elements and a PLASTIC_KINEMATIC material.
If I have the column set as a rigid material, the total model run time is 10 minutes, however as soon as I change it to a plastic_kinematic material the run time increases to 13.5 hours using just 800 shell elements to model the column.
Hello,
I'm modeling a tension specimen under displacement control by applying prescribed displacement to the node set, while from the output data, the motion of the node set is not moving as I prescribed. I'm using solid element -1. I wonder if anyone faced this kind of problem before?
Thanks,
Min-Chun
Regarding the user defined material, in the manual *Module can be used now to include the USDMAT is the standard LS-Dyna runs.
Thanks!
Hello forum,
I have seen and read many examples of ALE, but they all are FSI problems... I have two metals impacting at high velocities and want both materials to be ALE since both are deforming heavily i.e., I don't think Lagrange In Solid constraint is appropriate here.
Can anyone help me setup an ALE simulation that accomplishes this?
Thanks,
Peter Yip
Is it possible to use a user-defined material model (UMAT) with Smoothed particle Galerkin (SPG) method?
When I wanted to download LS-Dyna I needed an FTP login. I am a student and already have the free student version of LS-Dyna. I found some keyword files that I wanted to run, but I kept getting errors. Where I found those files, they said I need the double-precision version, preferably the MPP version. I couldn’t find anything about what version the student download of LS-Dyna is, so I went to the download page of LSTC. I saw that I needed an FTP login there, but I don’t have any. I hope someone can help me out with this.