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Found 7 results

  1. Hello, I want to model a suspension using 1D-Elements. CROD are used to model the rods from the chassis to the wheel carrier. They are connected to the chassis using RBE3 with dof123 constrained to allow for free rotation. The problem is with the connection to and modeling of the wheel carrier. The rods need to be able to rotate freely around the connection points to the wheel carrier as well. I know about BEAM-Elements but as far as I know they only allow for free rotation around 1 axis. ROD- elements shouldnt constrain the rotations either, but they added stiffness to the model compared to the last option, a simple RBE2 with dof 123 from the end points of the rod to the wheel center as a central node. This setup with an RBE2 with dof123 as a wheelcarrier works good in analysis, but in freeesize I randomly get the error " *** ERROR # 153 *** Exactly zero pivoting encountered during Numerical Factorization; the model may have rigid body mode. " - My question are as follows: Why dont rods work as intended? They shouldnt constrain rotation as far as i know - Why does the rbe2 lead to that error? in analysis the flow of force makes sense and no anomalies appear, sometime the freesize even completes without any problem at all. - do you know of any way to model freely rotatable 1D-elements aside from the options above? Below is a picture of the model:
  2. Hello, I would like to simulate a void as a region within my model that should not experience any deformation - to not damage any structure that may be place there e.g. a bearing. This is to be for a topology optimisation simulation, then how (if it is possible) can it be approached so that the optimal topology maintains the shape of the void? To expand, if I have a circular hole where a bearing should be placed and I do not want the deformation of the model to damage this bearing, how can I contrain the hole to maintain its shape during the topology optimisation? I would not like to use RBE2s or a nondesign space as this will effect the way the load paths are transferred. Will RBE3s work? If not, is there an alternative? Thank you in advance.
  3. プルダウンメニューFile⇒Run⇒Tcl/Tk Scriptから、下記のファイルを実行すると「RBE2_DOF-2456」のようにDOFに基づくセットを作成します。 CreateSetOfRBE2_DependsOnDOF.tcl
  4. Hello, I am looking to constrain a hole of a 3D model. I am currently using RBE2s (with all 6 DOFs on) within the hole and applying a constraint to the independent node in all 6 DOFs. Doing this I am able to successfully run the optimisation. However, I want to simulate a bar constraint where the model can rotate about the y axis but no others. I have tried deselecting the 5th DOF on both the RBE2s and constraint but this results in the optimisation failing. How do I go about applying constraints to all DOFs but 5 (moment around the y-axis)? Additionally, I am using RBE2s currently as I can apply a constraint to these. However, ideally I would be using RBE3s as these will better represent my problem. Is this possible to set up with the constraint in limited DOFs in mind? Thank you
  5. Dear Support Team, I use Hypermesh and Optistruct to build flexbody models to use in MSC Adams MBD models. Since my flexbody models are large and have too many unused DOFs, I need to reduce them only to ASET DOFs. In the particular problem I'm trying to solve, I have a machine part with a few ASETs to attach/constrain it and a single location where I get response data from. So, the only DOFs I need are the DOFs of this response location (in addition to the DOFs of other ASETs). I can put an ASET on this location but I don't know how to force Optistruct to output only ASET DOFs to the generated Adams MNF file. In the docs for Optistruct MODEL solver card, Comment #1 states that: "For CMS superelements output in h3d format, only the ASET DOF are output when the MODEL data is not present." I need this same effect but with MNF format and not h3d format, since I work with MSC Adams and not Motion View. I have tried a few ways on my own but have been unable to succeed. Any help would be greatly appreciated. Best regards.
  6. While analysing, we need to input constraints as BC. In constraints, there is checkbox and value for dof1,dof2,...amd so on. Checkbox is for enabling or disabiling dof, Why there is a text box for entering value? What does it siginifies?
  7. Hello, I am doing analysis of universal joint assembly (Yoke1, Spider, Yoke2). Spider is a cross member which has 4 bars extruded. So there are 4 revolute joints between trunnion and yokes. Can anybody tell me how to create a revolute joint using RBE2 elements in Radioss Bulk Data? https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQsTSispqWkYwMj6cy6vS8KmDxC2gM9aMmdf_Ffk06VMnPcRNnX To create a revolute joint between 1 bar and 1 yoke hole, I applied the following procedure: 1) Create a center node of the spider bar: node A 2) Create a center node of the yoke hole: node B 3) Create a RBE2 (Independent Node: node A, Dependent nodes: all the nodes on the portion of the bar which will be inside the yoke hole.) 4)Create a RBE2 (Independent Node: node B, Dependent nodes: all the nodes on the yoke hole.) 5) Create a local coordinate system having 'x' axis from node A to node B 6) Assign the node A and node B to local coordinate system. (set reference and set distance) 7) Create RBE2 (Independent Node: node A, Dependent nodes: node B; All dof constrained except dof4 (rotation in x axis) Is this method correct?
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