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Found 402 results

  1. Hi, I want to know if what I thought is correct. The interface setting of two shells is as follows. Top shell is 1T and bottom shell is 3T. Distance between two shells is 2mm. -> No initial penetration Igap determines how the size of the gap is calculated. Igap = 1 Then, in my model, Variable Gap = 2 And then my question is as follows. In this model, if Gapmin is 1.5 , contact force is applied when distance between two shells is 1.5 below figure?? (when 1.5 < distance between two shells, contact force is not applied??? ) Thanks
  2. Hi, I learned that when initial penetration is too deep, Fpenmax is applied. 'The node stiffness is deactivated if the Penetration ≥ Fpenmax * Gap, whatever the value of Inacti.' In above sentence, 'Penetration' is only initial penetration or any penetration? Thanks.
  3. Hi, In figure, two 1T shells are fixed on one edge. (Gap between 2 shells is 1.1) Interface between top and bottom shells is modeled by using /INTER/TYPE2. To set no relative motion, setting in type2 is default. Concentrated load is excited at node number 7 on top shell. Load curve and scale are as follows. (The load has effect like Impact.) I think that relative displacement between node 7 and 128 is perfectly zero because I use type2 default. However, in x,y,z direction, relative displacement occurs. It looks like almost zero but I want perfectly no relative motion. How can I set that? Another question is Physically the plate is excited by impact, acceleration of plate is decayed I don't use damping, so I think acceleration of some node is decayed to steady state response. But acceleration of node 7 is like this. Response is increased. Why??? Thanks
  4. Hi, I want to know contact force at each slave node or master segment. In /TH/INTER, I can check only the sum of contact force in contact interface. How can I check the contact force at each node? Thanks.
  5. Hi, I use /TH/INTER to obtain the contact force. In Radioss help, variable group is as follows. However, In Radioss, variable group is below. Which variable is absolute value? Thanks.
  6. Hi, In RADIOSS theory manual, Interfaces solve the contact and impact conditions between two parts of a model. In RADIOSS, It seems like that types of interface consider impact. I want to model the interface except impact. (only consider stick, slide) How can I do that? Thanks
  7. Hi, Warning is as follows. I connect the master node of the RBODY to beam element. WARNING ID : 448 ** WARNING IN RIGID BODY DEFINITION DESCRIPTION : MASTER NODE 1795 IS CONNECTED TO AN ELEMENT -- RIGID BODY ID : 1633 -- RIGID BODY TITLE : RIGID BODY ID 1634 PRIMARY NODE 1796 NUMBER OF NODES 8 SURFACE LINKED TO BODY 0 SKEW NUMBER 0 SPHERICAL INERTIA FLAG 0 REMOVE SLAVE NODES FROM RIGID WALL(IF=0) 0 CENTER OF MASS FLAG 1 ADDED MASS 0.000 ADDED INERTIA 0.000 0.000 0.000 0.000 0.000 0.000 SECONDARY NODES 1433 1435 1437 1456 1460 1471 1491 1495 Is it wrong? some nodes must be needed between master node of the RBODY and BEAM3N? Thanks
  8. Hi, CST setting ensures that time step is not less than user-defined value but it does not make time step smaller. Is there another way to reduce the time step except making mesh size small? Thanks
  9. Hi, I heard that Penetration is defined as the overlap of the material thickness of shell elements, while Intersection is defined as elements that actually pass completely through one another. My model is as follows. Thickness of the Solid component 'top' is 1T. When I make 'bottom', I use 'translate -> duplicate-> z-direction -1'. (Thickness of each component is 1T.) So I think there is no overlap between 2 solid components. But Penetration check tool detect penetrations. Why does it happen? It means there is overlap between 2 components? Thanks
  10. Hi, I want to know the reason why penetration occurs. auto1 : Length (x-direction) = 1000, Height = 100(y-direction), mesh size = 50 component1(yellow) : same as auto1. When I make component1, I use 'translate -> duplicate-> y-direction -100'. If I assign Property and Material on the components, Penetrations occurs. (If property and material are not assigned, penetrations does not occurs.) Why does it happen?? Thanks.
  11. Hi , I am working on modal analysis of rotor system in optistruct. I have queries regarding constraints. Pls find the following image which shows rotor assembly with bearing. I need to allow rotation free of rotor and shaft at bearing locations. How to give constraints at bearing locations ? Using RBE2 or any other options are there in Optistruct? Thanks Arul
  12. Hello Is it possible to model a 1D element that fails in either tension or shear? I would like analyze a breakaway feature on a structure that absorbs a portion of the impact energy and breaks off. Fracture can be either in tension (i.e cable) or in shear (i.e shear pin). Thank you
  13. Hi, I want to set the damping in the contact. Error message is as follows. I don't know what is wrong. What should do I set something?? Please advise me. Thanks.
  14. Hi, I am trying to simulate a bird impact on a plate with RADIOSS. So I am creating my model on hypermesh now, i chose to consider the bird as a fluid with a density of 438 kg/m3. I would like to work with SI units and the dimensions of the bird are : 0.1325m long cylinder with two hemisphere ends having a radius of 0.075m. I am now trying to mesh this geometry with the SPH module in hypermesh. So i entered a pitch of 1e-3m and a density of 438kg/m3 as i said before. But when i create the mesh, nothing happen and i only get this message "0 mass elements created". I attached my file with the topic. I don't know what could be my error, more of that I tried to do it using mm instead of m and it worked... But I really want to use SI units. Thank you in advance for your help, Gaspard. BirdStrikeSI.hm
  15. Hi, As shown in the figures, When I export 0000.rad file from .hm file (1st figure) and I import 0000.rad file, Rbody checking is removed and component name is changed(2nd figure). (RBODY -> RigidBody8) Why it happens? If I run this 0000.rad file, is it wrong? Thanks.
  16. Hi, I want to use /PRELOAD but I can't find it. I can't find it in load collectors. (I use RADIOSS 2019) Thanks
  17. Hi, I'm beginner of RADIOSS. I want to set the structural damping of steel. But I don't know how. I think there is no setting for structural damping in /DAMP , What should I do? Like OptiStruct(PARAM, G) , is there any card? Thanks
  18. Hello I am using RADIOSS to simulate a crash test which I have previously done. The trajectory of the impactor before impact is complex and requires several linkages and mechanisms to set up. The area of interest is the post-impact behaviour (stress/strain) on the target component, as well as the trajectory of the impactor. When I run the impactor by itself, to see the launch trajectory, I get a reasonable run time of about an hour. When I run the impactor with a simplified initial velocity + the target with all the contact and failure cards defined, I get a reasonable run of about 3 hours. When I run the full model: impactor with the initial trajectory + the target with all the contact and failure cards defined, I get a run around 12 hours to reach the impact, and another 12-24 hours to get results from post impact trajectory. I believe this is partly due the finer mesh required for the target model. I was hoping there is a way I can split the analysis in two, using the results from a the first as an initial condition for the second. Consider the following scenario: Model A: Simple model with only what is required to set off the trajectory of the impactor. The target is not modeled. Run from T=0 to T=T_impact. The run is stopped at the moment where the impact would have occurred. Model B: The target, with finer mesh and contact and fail definition is introduced, and the analysis is "RESTART" picking up from where Model A left off. In other words the target (with finer mesh) only appears just before impact onwards. This should theoretically cut down the majority of the analysis time. Is there a way to set up a RESTART file with introduction of new elements / properties / fail cards, and linking it to a "Stopped" run? I hope the diagrams attached illustrates what I'd like to do. Please let me know if there is a way to do this. Thank you. Best Regards, MN
  19. Hi everybody, could anyone suggest me how I can import stress from moldex 3D in radioss? Or, if it's possible to initialize stress with fields->value from .csv Thanks a lot.
  20. Hi, How to Clear the temporary nodes? Find the following Image. It is not cleared even it I use the option ( Shift +F2) and it is showing in Post processing. Is there any other way to clear?
  21. Hello , I am new to Radioss solver. Actually using it first time. I wanted to run a analysis for imposed displacement. Is there any tutorial available step by step. How to assign material, how to assign BC , loadstep, control card necessary for analysis. I have attached picture of which I am going for analysis.
  22. I'm trying to run a crash simulation and have encountered the element distortion/extrusion shown in the attached image. I don't know the correct terminology for this so it has been difficult to find solutions online. I believe it is caused by the contact interfaces and I have enlarged the gap min and told the nodes of deleted elements to be removed. There is also failure criteria which seems to have been ignored for these elements because they should have failed and been deleted. Any help would be appreciated.
  23. 有限要素法では要素毎の計算がいろいろと必要になります。例えば要素の応力から要素節点の節点力を求める、陰解法であれば要素剛性マトリックスを作成する、といった計算です。この計算では、例えばトラス要素であれば節点力は応力σに断面積AをかけてAσ、要素剛性はといった形で簡単に計算できますが、シェル要素やソリッド要素では要素の面積や体積での積分計算が必要になります。ただ一般の4角形や6面体の複雑な形状で直接計算を行うのは大変なため、一旦、これらの形状を正方形や立方体に写像を行い、定式はその写像された形状に対して行う、といった事が行われます。こうした要素をアイソパラメトリック要素と呼びます。 アイソパラメトリック要素では、4角形要素であれば、一旦-1から1の正方形領域に写像を行います。そうすれば、要素面積での積分は ここに、 という様に-1から1のξ、η平面での積分に置き換える事が出来ます。この面上での積分には通常、次に述べるGaussの数値積分が用いられます。
  24. Hi All, How can I decide the event time for Explicit simulations? since the actual event time will cost computing time By thumb rule 0.3 is the event time for quasi static analysis. Its derived from the natural frequency of the system/part. My doubt is whether I should consider the natural frequency of the entire assembly or the individual part under study? Thankyou N.K
  25. Dear Altair support team, Mr. Rahul R., I am working on optimization the vehicle crash box, I have some question about Hyperstudy / Hypermorph coupling for shape optimization. As first figure below, I created 2 Shapes (yellow and green) by translating the handles in -X,+X direction to increase the taper angle. In HyperStudy, I defined the model type as HyperMesh, while I am importing input variables from HyperMesh, they ask me to identify the lower and upper bound once (as second figure below). In this study, I would like to have the design variables including crash box thickness, shape1 and shape 2. Question 1. I seperated the shape into 2 because I have no idear to handle with them, can there cause any problem further? 2. If I want to keep the handle distance (+10,-10 in x direction) which is defined in the HyperMesh, Should I set up the input variables as following? Variable 1 (dv_1) Lower= 0, Nominal = 0, Upper = 10 Variable 2 (dv_2) Lower= 0, Nominal = 0, Upper = -10 Are there correct? Thank you for your calification. Best regards, Wisawanart
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