
Announcements

Please click here for a short but important announcement 03/26/17
Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding.

Leaderboard
Popular Content
Showing most liked content since 09/23/17 in all areas

2 likes

2 likes
Memory allocation
Bhaumik and one other liked a post in a topic by Q.NguyenDai
I think when you "allocate" 1500MB memory, Optistruct solvers understands that's the MAX limit of memory. So if your model is not so big the real used memory will be smaller that allocated value. 
2 likes
Add mass easily
Bhaumik and one other liked a post in a topic by George P Johnson
Hi, You can also try adding non structural mass in NSM option of PSHELL card, which assigns nonstrictural mass per unit area. Please go through the Help on the same. 
2 likesHi, Did you extract face elements of the elements which are part of hole on blue component? Also check the alignment as @tinh suggested. Another workaround (You don't have to create face elements) is to use Connectors>> Spot>> Spring. Select the nodes and components and create CELAS1 elements. Goto connectors browser and delete connectors (not connectors and FE) Now go to springs panel>> update>> change element type to CBUSH>> select all CLEAS1 elements>> update element type.

1 likeThnx tinh.I will try to finish the remaining

1 likeHi, The ideal shape for a tetrahedron element is an equilateral tetrahedron. Various quality parameters check how far a given element deviates from the ideal shape. And a similar quality parameter is tetcollapse. Tetcollapse is defined as the distance of a node from the opposite face divided by the area of the face multiplied by 1.24. Ideal Value of tetcollapse for a tetra element is 1.0 , and value greater that 0.1 is acceptable.

1 likeHi, Please find the image below which shows Analysis page and Radioss option to run the simulation.

1 likeHi @JamesMech Here are few suggestions from one of our experts: 1) Refine the mesh and make sure you apply the force on entire top face of the gear 2) Atleast 45 layers of elements along the thickness of the tooth to capture proper stress 3) If the displacements are huge, try with NLSTAT

1 likeHi Pohan, While opening HyperCrash select the user profile RADIOSS V14 and export the file. The file will be exported in 14 version. The other option is editing manually. Export the file from HyperCrash 2017 version. Open the *_0000.rad file in Textpad or Notepad and manually change 2017 to 140.

1 like

1 like

1 likeHi, In static or quasistatic analysis the load is applied slowly so that the structure deforms very slowly and the inertia force is very small, thus negligible. Opposite to this,if the force or load applied have a high rate of change of velocity during the process then it comes under dynamic analysis. Dynamic loads are always applied as a function of time or frequency. Since we are applying the loads with the high rate of change over a time the structural response will be also similar which results in high stress values. Please go through our ebook on Practical Aspects of Finite Element Simulation (A Study Guide) where the theoretical aspects of static and dynamic analysis are well covered with examples.

1 like
connections
dragon liked a post in a topic by dhananjay1308
I try to connect 3D mesh element and 2D element by 1D weld connector. just want to transform load and displacement from one part to another part. The weld property are not available. which type of connector should prefer.(rbe2 and rbe3) 
1 like

1 likeI thinh there is it in force panel. Dont you see it?

1 like

1 likeHi Abhay, Always use different directories for multiple runs. anyway now you have different inp files use below command acuTrans pb [inp file name without extension] out extout to ensight for more help on acuTrans command type.... acuTrans h in the command prompt if the same inp file is used for multiple times for run then log file will be with extension of run ids. in that case use below command acuTrans pb [inp file name without extension] out extout to ensight run [Run Number] Regards Ravi Harti

1 likeThank you! It worked.

1 likeHi @luisousa.92 You can start trimming with small portions and make the solid mappable. If the model is symmetric, you can slice into two half and use one half form trimming and meshing and reflect the elements at the end.

1 likeHi Mohamed, Thanks for the model. There are a few things that could explain why you're not seeing the characteristic modes in the attached model: The model doesn't contain any geometry. There is only an infinite ground plane and a cable instance, both of which are approximations that can be used instead of complex geometry. For characteristic modes, a model that will be solved using the Method of Moments (MoM) is needed. In other words, there typically needs to be CAD that can be meshed into triangles and wire segments. The ports for the model are both Finite Element Method (FEM) line ports. FEM is a separate solver from MoM and doesn't support characteristic mode analyses. Neither port is excited or connected to anything. I recreated what I think the model is trying to do (see stright wire modified.cfx) using MoM. Note that you need to add the requests that you are interested in; at the moment only the characteristic mode eigenvalue data is being calculated. Are you trying to reproduce results from an article/measurements/calculations? Do you have any reference data? Without further information, this is as far as I can go. I would urge you to go through the Examples Guide and some overview documents on the feko.info website: http://feko.info/productdetail/productivity_features/characteristicmodeanalysis/characteristicmodeanalysis_6_3 http://feko.info/applications/whitepapers/intelligentdesign/CMA

1 likePlease equivalence nodes with tolerance of .0001.This will merge all nodes.

1 likeHi, Yes, even if it is connected by an element it will show connectivity. You can try with Check Connectivity option in HyperCrash.

1 likeThank you, its a simple and elegant solution and it works perfectly !

1 likeHi, I don't think it's possible to display the units.

1 like

1 likeHi, For adjusting the normals, please go to the Normals Panel (Shift+F10) and adjust. We cannot change the normals from the _0000.rad file. In Type 14 property we don't have an option for normals. If you want to check normals for solid elements create a skin element layer (Tools>Faces, create face for the solid component) and check the normals.

1 likeHi, you have to convert components to local system like this: set X [hm_getentityvalue loads $loadid baselocationx 0] set Y [hm_getentityvalue loads $loadid baselocationy 0] set Z [hm_getentityvalue loads $loadid baselocationz 0] set C1 [hm_getentityvalue loads $loadid comp1 0] set C2 [hm_getentityvalue loads $loadid comp2 0] set C3 [hm_getentityvalue loads $loadid comp3 0] set Sid [hm_getentityvalue loads $loadid inputsystemid 0] set localC1 [hm_xpointvectorlocal $Sid $X $Y $Z $C1 $C2 $C3] set localC2 [hm_ypointvectorlocal $Sid $X $Y $Z $C1 $C2 $C3] set localC3 [hm_zpointvectorlocal $Sid $X $Y $Z $C1 $C2 $C3]

1 likeHi, assumption:  you have a cylindrical mesh (not have surf)  mesh is quad only, equally then, the proc below will select a circumference nodes base on a preselected node not lay on ends of cylinder you can modify it to select nodes at 2 ends of cylinder (it's easy) proc ::p_SelectCircumferentialNodes {{PreselectedNodeId {}}} { if {![hm_entityinfo exist nodes $PreselectedNodeId]} { *createmarkpanel nodes 1 "Pick a node on cylinder:" if {[hm_marklength nodes 1]!=1} return set PreselectedNodeId [hm_getmark nodes 1] } #we will find 4 quads attached to the node: *createmark elems 1 "by node" $PreselectedNodeId if {[hm_marklength elems 1]!=4} {*clearmarkall 1; return code error "not valid cylinder"} if {![string equal 104 [lsort unique [hm_getmarkvalue elems 1 config 0]]]} {*clearmarkall 1; return code error "not valid cylinder"} lassign [hm_getmark elems 1] Elem1 Elem2 Elem3 Elem4 set nx1 [hm_getentityvalue elems $Elem1 normalx 0] set ny1 [hm_getentityvalue elems $Elem1 normaly 0] set nz1 [hm_getentityvalue elems $Elem1 normalz 0] set NodeList [hm_nodelist $Elem1] set nx 0; set ny 0; set nz 0 set TripleCosMin 1 foreach ElemId [list $Elem2 $Elem3 $Elem4] { if {[llength [lsort unique [eval linsert [list $NodeList] end [hm_nodelist $ElemId]]]]==6} { set nx2 [hm_getentityvalue elems $ElemId normalx 0] set ny2 [hm_getentityvalue elems $ElemId normaly 0] set nz2 [hm_getentityvalue elems $ElemId normalz 0] set TripleCos [expr abs([hm_triplecos $nx1 $ny1 $nz1 $nx2 $ny2 $nz2])] if {$TripleCos<$TripleCosMin} { set TripleCosMin $TripleCos set nx $nx2 set ny $ny2 set nz $nz2 } } } if {!$nx&&!$ny&&!$nz} {*clearmarkall 1; return code error "not valid cylinder"} set vx [expr $ny1*$nz$nz1*$ny] set vy [expr $nx1*$nz$nz1*$nx] set vz [expr $nx1*$ny$ny1*$nx] list $vx $vy $vz *appendmark elems 1 "by attached" *findmark elems 1 1 1 nodes 0 2 lassign [join [hm_nodevalue $PreselectedNodeId]] x y z *createmark nodes 1 "on plane" $x $y $z $vx $vy $vz 0.1 1 1 *markintersection nodes 1 nodes 2 hm_highlightmark nodes 1 h *clearmark nodes 2; *clearmark elems 1 }

1 like
table
mahes liked a post in a topic by Livil Lyle
Hello Mahes, I agree to that, you can do a Find in Files search for "hwtk::table" inside the scripts folder (C:\Program Files\Altair\2017\hm\scripts) using notepad++ or any other code editor to get few more tcl programs using table. 
1 likeHi They are local coords retieved by datanames localx localy localz set X1 [hm_getentityvalue nodes $node_id localx 0]

1 likeHi Marvin, I did not notice the K1 factor and load change. I will check this. You can create a local system and set the local system to elements.

1 likeYes that is because of the I made the CBUSH rigid just to check if this is valid. Without CID solver gave a random displacement and with CID set to zero it is giving expected results. it is recommended that another CID be selected to define the element xaxis.

1 like
CBUSH SPRING
Rahul R liked a post in a topic by marvin1991
But your result is not making sense or? You have the highest displacement at the constrainsts. But the force is in the middle, between the springs. And even inthe middle the displacment is 1,9*10^9 in the girst example. Thats nearly 0 .. 
1 likeHi, If the mesh quality is poor the solver will show the error and you have to remesh / improve the mesh quality. From the automesh panel (F12) select elements from the entity selector and select the existing elements which has the poor mesh and perform remesh of that region. I recommend you to go through Practical Aspects of Finite Element Simulation (A Study Guide) ebook where mesh quality improvement tips are provided (page 242). Material and property assigned to the component will remain in the same. But you may have to update the BCs and loads in the elements remeshed.

1 likeHi, Please find the video attached which shows Airbag Simulation. Also, please go through https://www.youtube.com/watch?v=kCSRFss6GDE&list=PLQ7KUGFuVz4u5y3SvIEIU07427gATaG6&index=5 which is a webinar showing creating monitored volume in RADIOSS. Hope this helps. Airbag_simulation_setup_.mp4

1 likeIn HyperMesh 13.0 version. you can find the same at Analysis > Control cards >Global output request. In Altair Help Home page you can check for release notes which gives information on enhancements in the latest release. Meanwhile I suggest you to upgrade to HyperWorks 2017 version, which is the latest with many capabilities added. Please explore the same. You can download it from https://altairuniversity.com/freehyperworks2017studentedition/

1 likeFor contact condition, you not need to make coincident mesh between two parts.

1 likeHi, From the quick edit (F11) option toggle the 'split' in the fillet and try defeaturing.

1 likeHi Pohan, These are different solid formulations. And i think this is due to the Isolid=17 hasn't the free shearlocking fonctionality like Isolid=14 which can result in different deformation.

1 like

1 like
Solid Map
frzti liked a post in a topic by George P Johnson
Hi, Solid map option works relatively for simple solids; complex objects must first be partitioned into simpler sections so that the sections can be meshed individually. Even if all solids are mappable, they may not all be meshable at once; User has to mesh each mappable solid individually. I'm attaching a tutorial with model file which shows solid map function for a similar model mentioned. HM3220.pdf solid_map.hm 
1 likeHello andries, Thank you for your suggestions. Yes example guide is good way . Finally, I got the plot . Thanks

1 likeTinh, Thanks for suggesting the Transform tool. Exactly what I was looking for!

1 likeDid you try enter menubar Tools>Transformation ?

1 likeHi Gopal, The following available kinematic conditions are supported in RADIOSS Implicit: •Boundary conditions /BCS •Imposed displacement /IMPDISP (velocity /IMPVEL, and acceleration /IMPACC) •Rigid bodies /RBODY •Interface type 2 /INTER/TYPE2 •Rigid walls /RWALL (not recommended due to performance reasons. Use contact interface, if possible.) •Interpolation constraint element /RBE3 •Rigid element /RBE2

1 likeHi please watch my video, sorry for the long delay

1 like

1 likeThe equation of motion for a static analysis is as below: [K] {X} = {F}  (1) [K] > Global Stiffness Matrix {X} > Unknown Displacement {F} > External Force Applied. For the body to be in static equilibrium, the net force acting at every node must be zero. Therefore, the basic statement of static equilibrium is that the internal forces, I, and the external forces, F, must balance each other: [K] {X} is nothing but internal force 'I' Equation (1) now becomes, ==> I = F or I  F = 0 (2) In Dynamic Analysis, the imbalance between the external and internal forces results in an acceleration: F  I = M a. F > External Forces I > Internal Force M*a > Inertial Forces (mass times acceleration) In linear static analysis the stiffness matrix is constant and shall not change/update throughout the analysis. There are many check need to be performed once you have linear static results for well conditioned problems. The equation (1) is decomposed one time to find the unknown displacement. [K] {X} ={F} After decomposition, a singularity may lead to an incorrect solution. In static analysis to obtain {X} (displacements). Using these displacements, One can calculate a “residual” loading vector as follows: [K] {X} {F} =δ F This residual vector should theoretically be null (equation 2) but may not be null due to numeric roundoff. In Nonlinear static analysis, The stiffness matrix changes in each and every iteration since the stiffness matrix is dependent on the external load. The external load in Nonlinear static analysis is applied in increments and time here has no physical meaning. Time is just a convenient way to apply full load in nonlinear static analysis. In Optistruct the incremental load is controlled by 'NINC' field in the NLPARM card for NLSTAT load steps, this is a fixed load increment method. If you add the PARAM,EXPERTNL,YES to the deck, the time increment method becomes automatic in which case, the increment (load) is increased or cut back based on the convergence rate. NLGEOM loadstep has automatic time step by default. In NLGEOM loadstep the RAMP load curve can be defined using TABLED1 card and then refer this in NLOAD1 card. In nonlinear static analysis, OptiStruct uses the NewtonRaphson method to obtain solutions for nonlinear problems to maintain the residuals close to zero (equation 2) In a nonlinear analysis the solution usually cannot be calculated by solving a single system of equations, as would be done in a linear problem. Instead, the solution is found by applying the specified loads gradually and incrementally working toward the final solution. Therefore, OptiStruct breaks the simulation into a number of load increments (NINC) and finds the approximate equilibrium configuration at the end of each load increment. It is important that you clearly understand the difference between an analysis step (NLSTAT / NLGEOM), a load increment (NINC of NLPARM card), and an iteration (MAXITER of NLPARM card) The load history for a simulation consists of one or more steps. Within a step you will have many no of increments (NINC), within increment there can be many no. of iteration (MAXITER). OptiStruct checks the equilibrium equation ( equation 2) for each and every iteration. If the solution from an iteration is not converged, OptiStruct performs another iteration to try to bring the internal and external forces into balance. An increment is part of a step. An iteration is an attempt at finding an equilibrium solution in an increment when solving with an implicit method. If the model is not in equilibrium at the end of the iteration, OptiStruct tries another iteration. With every iteration the solution OptiStruct obtains should be closer to equilibrium; sometimes OptiStruct may need many iterations to obtain an equilibrium solution. When an equilibrium solution has been obtained, the increment is complete.

1 like
pin joint creation
Ivan liked a post in a topic by Rahul R
RBE2 should be connected to all dependent nodes & with independent node you can connect bar element.See attached video. rigidbar.mp4 
1 likehi Karthi use "cd" command cd "C:/folder" but you already use *jpegfilenamed so it's better to direct path in filename: *jpegfilenamed "C:/folder/$compname"