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Found 402 results

  1. Hi, The airbag injectors are defined by a function of mass/time so it takes some trial and error to converge on the pressure required. Is there a more direct way to determine the pressure at the end of inflation?
  2. Hi Support I am running crash can crushed by a wall with RADIOSS using Implicit option, but the run stopped simply at cycle 0. I suspect it might have to do with my engine file. could you take a look at the engine file and out file? p/s: I will send the starter file if required, but I can't post it here due to confidentiality Thanks try_Run_0000.out try_Run_0001.out try_Run_0001.rad
  3. Hello, I use Radioss for a dynamic impact problem, but also for the moment to validate my model through a quasi-static analysis. A first component compresses a second component with an imposed velocity. The interface between them is of type 7. In dynamic explicit simulation the interface works fine but in the implicit simulation, I get a warning in interface : "NODE ... DE-ACTIVATED FROM INTERFACE". If I make an "initial penetration" (initial gap < gapmin entered into type 7 interface) I do not get this problem (however I get initial constraints I want to avoid). Would anyone know what the problem might be ? Hereunder a part of my engine.out file: -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- CYCLE TIME TIME-STEP ELEMENT ERROR I-ENERGY K-ENERGY T K-ENERGY R EXT-WORK MAS.ERR 0 0.000 0.2000E+05 SOLID 39426 0.0% 0.000 0.000 0.000 0.000 0.000 ANIMATION FILE: pression_statique_07A001 WRITTEN ***** WARNING : ELEMENT FORMULATION ISOLID= 0 IS NOT AVAILABLE FOR STIFFNESS MATRIX BUILDING, USING GENERIC ONE INSTEAD POSSIBLE CONVERGING ISSUE. ***** *--------- STIFFNESS MATRIX SETUP ---------* SYMBOLIC DIM : ND = 155532 NZ = 2897175 NB_MAX = 26 FINAL DIM : ND = 47480 NZ = 761383 NB_MAX = 26 --STIFFNESS MATRIX WILL BE REFORMED AFTER EACH 3 ITERATIONS-- * CONVERGED WITH 0 ITERATIONS, |du|/|u|,|r|/|r0|,|dE|/|E|= 0.1000E+01 0.0000E+00 0.1000E+01 WARNING INTERFACE 701 NODE 13703 DE-ACTIVATED FROM INTERFACE WARNING INTERFACE 701 NODE 13548 DE-ACTIVATED FROM INTERFACE WARNING INTERFACE 701 NODE 13693 DE-ACTIVATED FROM INTERFACE ANIMATION FILE: pression_statique_07A002 WRITTEN * IMPLICIT COMPUTATION TERMINATED WITH TOTAL NONLINEAR ITERATIONS: 0 * TOTAL NUM.OF MATRIX FACTORIZATION AND PCG ITERATION: 0 0 RESTART FILES: pression_statique_07_0001_[0001-0001].rst WRITTEN ------------- ** CPU USER TIME ** #PROC [K]SETUP [M]SETUP IMPL.SOLV IMPL.TOTAL 1 .4862E+02 .0000E+00 .0000E+00 .4930E+02 #PROC CONT.SORT CONT. F ELEMENT KIN.COND. INTEGR. I/O TASK0 ASSEMB. RESOL 1 .5591E-01 .6813E-02 .2678E+00 .2133E-01 .4654E-03 .5012E+00 .9117E-03 .1199E-01 .5030E+02 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Thank you a lot, Kinds regards, Alice
  4. Dear All, if I only have yield strength, ultimate tensile strength, poisson's ratio, and density data, can I get value for a, b & n for Johnson-cook material? Thank you for your help
  5. Hi I'm now working on BirdStrike Analysis using RADIOSS140. Like many paper on birdstrike analysis reports, I've done a reproduction of birdstrike experiment carried out by Wilbeck in 1977 [1]. The resultant pressure PH(*1) and PS(*2) meets with theoretical value very well. Except that,if you look at the pressure curve, there is a "ZERO Pressure" period just after the first contact. Taking closer look into the animation, the SPH bounce back just after the contact. Such blank period doesn't appear in the experiment result,or analysis results of other researchers report. [Question] : Is there a way to correct this ? Model setting is follows. -bird is using SPH. Material law is MLAW6 (Equation of State). -Using contact TYPE7. Istf = 1 StFac = 550 … recommended value by Altair Support Igap = 0 gapmin = h/2 (h = SPH radius) … recommended value by Altair Support I've varied the value of these parameters which didn't make any difference on "ZERO Pressure" period. ******************* *1 … PH: the peek pressure just after the contact(Hugoniot Pressure) *2 … PS: the constant pressure when bird deformation can be seen as constant flow.(Stagnation Point Pressure) [1]:J. Wilbeck,AFML-TR-77-134 1977 161121_Bird Strike experiment reproduction by RADIOSS.pdf
  6. Hi I am trying to simulate a impact condition . Simulation is running but steel sphere is not penetrating the sandwich panel . I am attaching the file here can any one suggest me how to proceed in this . I have used johnson cook plasticity model for aluminium . Cantilever_Impact_NAL_17_16_0000.rad
  7. Hello, I'm trying to convert an I beam composite model after a freesize optimization to radioss to evaluate some failure criterions that doesn't have on optistruct like puck or hashin I'm having the error on the image. Some suggestions ? Thanks !!
  8. Hello, I wanted to know whether the internal energy curve from T file is strain energy or strain energy density? Also, how do I get the contour plot for strain rate experienced by each element?
  9. Is it possible to define the contact ( surface to surface , single surface contact) between components in vibration analysis ( Modal , FRF) in optistruct?
  10. Hello, I am studying the compression of a soft material (hyperelastic) with RADIOSS. But it seems like a hourglass effect happens during the compression (as you can see on the attached screenshots). - I used [Ismstr] =2 and [Isolid] =1 - with /DT/BRICK/CST 0.67 0.0001 - material=LAW42 (Ogden) nu=0.495 (incompressible) I can send you the .RAD files if possible. I am trying full integration [Isolid] =12, but the computation time is really (really) increased even if the result seems better (for the begining of the compression). I also got a poblem as the script in the other screenshot. I do not really know where it comes from... If you can help me please? Thanks, Corentin
  11. Guest

    Hyper-Velocity impact

    Dear George I want to know is it possible in radioss to do hyper velocity Impact , i,e projectile traveling with velocity of 1 t0 10 KM/s (kilometer/second). If you have any literature/case studies or anything kindly share with me . I would also like to know from you whether for high velocity impact Hypercrash is good or radioss
  12. Hi, I am working with radioss solver for adhesive modelling. Material model MAT/LAW83: Alpha: -100 Beta: 1 SN connect Failure model: Fct_0N:4 , Fct_0S:7, Fct_FN:90, Fct_FS:16 Alpha_0 : 50, Alpha_F : 50, Beta_0_F:2 The force vs. displacement graphs when working with KSII-90° and KSII-peel simulation models is showing a significant variation in output. Please find the graph attached, BC -000111 artificially applied to cohesive element nodes. The observed graph with BCs are similar to my experimentation results, does that mean I need to always apply BC 000111 to cohesive elements? Any explanation on why this is happening, could be of great help. Regards, Chaitanya Master's student
  13. Hello, I am doing a crash simulation using RADIOSS. I would like to get the Kinetic Energy of the entire component as a graph vs time. How do I get this?
  14. Is it possible to calculate the Stiffness (N/m or N/mm) of the structure from any analysis??
  15. Thank you George for the reply. So for any analysis until we use the control card for Implicit, will it always run an explicit analysis?? Also I have one more question, what is the error and mass error here ? CYCLE TIME TIME-STEP ELEMENT ERROR I-ENERGY K-ENERGY T K-ENERGY R EXT-WORK MAS.ERR 3500 0.3713E-02 0.1048E-05 SHELL 106239 0.1% 0.1060E+07 0.7229E+08 0.1347E+05 -0.2986E+06 0.000 Is it the error, the error of the external force to the internal force?
  16. How to give a concentrated(point) load on a moving body in radioss. The load is given perpendicular to moving direction of the body.
  17. Hi, I am simulating in Radioss a fabric hinge (similar to a living hinge with flexible woven material). Using M19_FABRI material card in combination with P9_SH_ORTH property card I can simulate the out-of-plane bending of the fabric hinge. But simulating the in-plane shear is challenging. In the attached image, the gravity is acting in negative Z direction and the sample is fixed encastre on the left side. The expected behaviour is collapse of the fabric hinge in the middle (between two wood panels). However the sample is behaving like it is made out of uniform elastic material and is only deforming slightly (defromation is 1000x scaled). Does anyone have an explanation? I would also like to use the same material in Optistruct, but I could not find equivalent material law for flexible fabric. any suggestion would be appreciated
  18. When running my file on RADIOSS I am getting the following error and am not sure as to why since I can't see anything wrong with the function syntax. ERROR ID : 54 ** ERROR IN INPUT FORMAT DESCRIPTION : IN BLOCK : /FUNCT/30 ERROR ID : 54 ** ERROR IN INPUT FORMAT DESCRIPTION : IN BLOCK : /FUNCT/30 ERROR ID : 54 ** ERROR IN INPUT FORMAT DESCRIPTION : IN BLOCK : /FUNCT/30 FUNCT/30 is located in an include file named Database_v13a.inc and this is the function Thanks, Rob
  19. Hi, I'm new to radioss. I'm carrying out roll over analysis on box as shown in attached image. i've assigned initial velocity along axis and got the box rotating, the problem i'm facing here is the box is being thrown upward and its not falling on the base.do i need to assign gravity? if so how? for the same i tried giving initial velocity to the platform holding the box, the analysis showed platform pushing the box upward same as in first case. how to achieve a tilting scenario in this case?
  20. Dear All, I want to ask about RBE2 application, please see my picture below. I have a simple plate, and I want to give constraint on 2 holes on top, and forces (160kN on both hole or 80kN each hole) on 2 holes on bottom Why my simulation result (stress & deformation) totally different?, because in my opinion, case on the problem 1 and problem 2 are same.... Am I miss something? Best regards, Iron_Man
  21. Hi, Is it possible to do Modal analysis for rotor with shaft ( using 3D elements) using following example in optistruct?. or it is applicable for only 1D elements problem?? I have tried . But it is not working for 3D problems OS-1372: Rotor Dynamics of a Hollow Cylindrical Rotor
  22. Dear All, I need the model on this link http://www.altairuniversity.com/analysis/structural/nonlinear/beam-thermal-loading-unloading-nlstat/, because the link to download is broken. Thank you, Best regards, Iron_Man
  23. Hello everyone, I've just tried to use HyperMesh 12.0 but I have some problem. I didn't find the Bulk Data in Radioss on User Profiles panel. There are Block120 , 110 100 ,90 ,51, 44 ,42 and Fix41 but no ''Bulk Data'' so I can't run my work. Thank you in advance.
  24. Hi! Could ssomeone help with the following problems please? I defined two surfaces with shell elements and an imposed displacement in the middle of the circle(-2,044mm in Y axis) I don't know how to define correctly the contact between these two meshes. I tried it with TYPE7 and TYPE11 as well. I got the same result. Which type should i use and how to properly define them? There is also a gap between meshes and the two pionts(the top point of the rectangle has another displacement as the bottom point of the circle with IMP DISP ). How is that possible? Why is there a gap between meshes? I defined shells with thickness 15. Thanks in advance!
  25. 接触条件や結合条件等の拘束条件を表すための方法としては、いくつかの手法があります。例えば、節点1と節点2の変位が等しい、 u1=u2 という条件を表すためには: マスター・スレーブ型運動条件 これは、どちらかの変位(例えばu1)を独立変数とし、もう片方を従属条件、とします。運動方程式を解く際には、u1だけで解き、その後得られたu1をu2に代入すれば、この拘束の条件が、満たされます。つまり、独立節点(マスター節点)だけで先に運動方程式を解き、従属節点(スレーブ節点)は得られたマスター節点の値から拘束条件を満たすように強制的に動かす、と言う方法です。 かなり乱暴な方法ではありますが、一般に陽解法では時間ステップが非常に小さいため、このような方法でも可能になっています。 ペナルティ法による拘束 変位の拘束条件: u1-u2=0 に対して、以下の式 p(u1-u2)^2 / 2 を考え、これを有限要素法のエネルギー方程式に付帯条件として付加するのがペナルティ法です。pがペナルティパラメータと呼ばれ、これに対して大きな値を与える事で、近似的に変位の拘束条件を満足させます。構造問題の変位の拘束に対して用いられた場合、ペナルティパラメータはばね定数に相当し、変位の拘束条件を満足させる為に、硬いばねで結合した事に相当します。ペナルティ法は近似的な拘束条件ですが、その扱いが簡単なことから陰解法、陽解法を問わず、広く用いられています。 ラグランジュ法による拘束 変位の拘束条件に対してラグランジュ定数λを導入し、 λ(u1-u2) を有限要素法のエネルギー方程式に付帯条件として付加した上、λでも変分を取るのがラグランジュ定数法です。これは、運動方程式に、拘束の方程式を連立させて解くことに相当します。拘束条件の表し方としては、最も厳密な手法ですが、計算の手間も大きくなることから、主として陰解法で用いられる手法です。但し、Radiossの接触、運動条件にも一部導入されています。 タイドインターフェース(Type2)は、元々節点位置が一致しない異なるメッシュ同士の結合方法として考案されました。ベースになる考え方はマスター・スレーブ型で、マスターセグメントの節点を独立節点(マスター節点)とし、セグメント上のスレーブ節点に掛かった力、モーメントはこのマスター節点に分配した後に、マスター自由度のみで運動方程式を解き、その変形が得られた後、スレーブ節点はマスターセグメント上でのアイソパラメトリック座標が変わらないように強制的に移動されます。 このように、元々は異なるソリッド等のメッシュの結合として生まれたType2インターフェースですが、スポット溶接を模擬するbeam_typeスプリングをメッシュに結合するためにもType2インターフェースが用いられるようになっています。元々のスレーブ節点への力、モーメントのマスター節点への分配が単純分配(spotflag=0)であったのに対して、こちらの手法では、ビームタイプスプリングへの力、モーメントがマスター節点の力と釣り合うように分配されます(spotflag=1)。但し、どちらもマスター・スレーブ型の運動条件ですので、スレーブ節点は従属自由度で、その節点に新たに別の拘束条件が加わると矛盾(運動条件の非適合)が生じます。そこで、この非適合の問題を避けるためType2インターフェースに対してもペナルティ法に基いた拘束(spotflag=0、1に対応してそれぞれ27と28)が導入されています。
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