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About GH_yoshida

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  1. Hi Johnson, sorry for late reply. As you advised, I moved masternode of 1 of the 2 RBODYs slightly and defined another constraint. The ERROR 442 disappered completely! thanks alot.
  2. I'm building RADIOSS model of a square plate under impulse loading to calculate the reaction force. The boundary condition is follows, -<A> full constraint on the 4 edges (RED in picture) and -<B> only translation in out-of- plane direction is constrained on some area of the plate(Blue in picture) In order to create this B.C.s, I used 2 RBODYs which share the same master node. The master node is fully constrained by SPC and output of REACX on that node is defined to output reaction force. Running RADIOSS returns ERROR 442, ** ERROR IN RIGID BODY DEFINITION DESCRIPTION : -- RIGID BODY ID : 47869 -- RIGID BODY TITLE : AT LEAST TWO RIGID BODIES USE THE SAME MASTER NODE ID=87278 I know switching either of RDOBYs to SPC will fix this problem but I can't get correct reaction force. Is there any way to go through this problem?
  3. Dear Johnson Thanks for the quick reply. Initial velocity is 200m/sec,as the experiment is done in 100 to 300m/sec range. Unuits used is [ton/mm/sec] ,so the same as your model. I've attached my .hm file. If you find any suspicious or incorrect settings,Please Let me know. I've varied some parameters before (including gapmin) but it didn't resulted in major differences. But I'll re-check in wider range of value. Other difference I noticed in your model is follows. ■1.Initial Velocity Large difference(3m/s VS 200m/s) in InVel might affect the result. I'm running your model with 200m/sec InVel to see if "bounce" be observed. ■2.ANIM_DT In order to draw a very smooth curve in HyperView, I set ANIM_DT as short as 5e-008 sec. If the animation is corse, you might be missing the phase of bouncing. ■3.DTIX The same reason as 2. ,I'm using "/DTIX" card to limit timestep smaller than 5e-009. Anyway, I'll change Invel,ANIM_DT,DTIX in your model and see what happens. Thanks. ImpactTest_B10-200.hm
  4. 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
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