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Jeugarcon

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  1. Thank you for your reply, Andy. The video is useful and explains the mesh problem in long bars. The ratio of the coarse and fine mesh in my model is 5:1, it's not so big as in the video. I found that the nodes in the coarse and fine mesh interface are not equivalent, so I made them equivalence. Best
  2. Hello, I'm doing Split Hopkinson Bar simulation with Radioss, as depicted below in Fig. 1, I refine the mesh in the middle of the incident bar in order to use them as strain gauge to measure strain signals. But when I conduct the simulation, the strain propagation stops and reflects when it spreads to the refined mesh(Fig.2). And the coarse elements pass through the refined elements(Fig.3). However, the strain can spread to the end of the incident bar when I mesh the bar with the same coarse elements. It's so strange because I only refine a small part of the bar mesh, in order to measure the precise strain signal (I can't refine all the mesh because of the calculation efficiency). Could someone figure out where the problem is? Any help would be appreciated. Best Fig. 1 Fig. 2 Fig. 3
  3. Hello, I'm doing Split Hopkinson Bar simulation with Radioss, as depicted below in Fig. 1, I refine the mesh in the middle of the incident bar in order to use them as strain gauge to measure strain signals. But when I conduct the simulation, the strain propagation stops and reflects when it spreads to the refined mesh(Fig.2). And the coarse elements pass through the refined elements. However, the strain can spread to the end of the incident bar when I mesh the bar with the same coarse elements. It's so strange because I only refine a small part of the bar mesh, in order to measure the precise strain signal (I can't refine all the mesh because of the calculation efficiency). Could someone figure out where the problem is? Any help would be appreciated. Best Fig. 1 Fig. 2 Fig. 3
  4. Thank you Andy, your response is quite useful for me. Another question is: I'm now using Radioss v14, is it necessary to update Radioss version? Or I only need to write and compile the subroutine according to the newer documentation? Best
  5. Thank you for your reply, Andy. Could you tell me some newer features in Extended Material Laws or share some documentations about it? Because in "RADIOSS User's Code Interface 14.0 version", it says the variables in Extended Material Laws are transferred through USERBUF, there's no detailed explanation. Thanks in advance. Best
  6. Dear all, I have a question about the Deformation gradient F and Stretch tensor U in USER material routines. Do F and U already exist in Radioss routines? Because when I write a linear isotropic elastic material subroutine, I don't need to use deformation gradient F. But when I develop hyperelastic materials using USER material routines, I need to use deformation gradient F. Do I only need to declare F like this in engine subroutine, and then I can use them to calculate stress tensor directly because they already exist and are calculated automatically in Radioss? DOUBLE PRECISION .FPSXX(NEL),FPSYY(NEL),FPSZZ(NEL), .FPSXY(NEL),FPSYX(NEL),FPSXZ(NEL), .FPSZX(NEL),FPSYZ(NEL),FPSZY(NEL) Here is a slide from a tutorial of Radioss User Subroutines: Besides, for "Extended User Material Laws", in Chapter 3 of "RADIOSS User's Code Interface", the data structure USERBUF doesn't contain FPSXX, FPSYY, FPSZZ etc. Which confuses me is how to use Deformation gradient F when write Radioss usermat subroutines? More precisely, if F already exists in Radioss routines, I only need to declare them and use them directly? Could someone answer my question? Any help would be appreciated. Best
  7. Hello, In "RADIOSS User's Code Interface", there 2 types of usermat laws, one is "User's Material Laws" and the other is "Extended User Material Laws". 1. What's the differences between the 2 different types? Or the latter "Extended User Material Laws" is only a quantitative extension of the former "User's Material Laws"? (That means someone can use more than 3 user-defined materials at the same time?) 2. If I only write one user-defined material, I can use any of them? It doesn't make any difference? Could someone answer my doubt? Thanks a lot. Best
  8. Thank you Hyperman, the corrected model can simulate. I have some doubts. 1. In the corrected model, a rigid body is used to put 'fix' and 'imposed velocity' boundary conditions, what's the function of load collector 'displacement_spc'? 2. In interface type7 settings, slave is component cylinder, what's master interface? Because the cylinder has 2 interfaces with upper and lower plate. 3. For user comments, what's the differences between Do Not Export and Hide In Menu/Export? 4. If the interface is Type 19, I need to put a physical initial gap when modelling rather than just adjust the interface setting parameters? What confuses me is that whether there needs a physical initial gap or not.
  9. Hello, I created a compression simulation model (a cylinder between a fixed plate and a flexible plate), it has warnings(initial penetration in interface) when calculating and the calculation time increases continuously. I've read some posts and I used the check tool to fix the intersections automatically. Also, I chose interface TYPE19 between contact surfaces of plate and cylinder, I set Igap=1,Inacti=6. I doubt maybe the mesh is not good or there are some problems in contact interface settings(there is no physical gap between plates and cylinder when modelling). The attached files are solver decks. Could someone help me to find out the problems? plate_cylinder_0000.rad plate_cylinder_0001.rad
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