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ulrichliebminger

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About ulrichliebminger

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  1. Thanks! Tried it but got the same error occuring...
  2. The starter and engine out files are below. I also attached the model itself so that you can take a look at my damping function yourself. Apart from that I attached also two pictures of my spring property I tried to compare with. (one where K and C got defined in its assigned box and one where I defined the two parameters via a function and as I have already mentioned above, the spring comparison worked out fine, but the damping function has some failure in it...) By studying your advised literature I came up with some ideas, even tough there is unfortunately no description of how to input or set up a damping function...But my ideas failed every time, unfortunately... May you come up with some further ideas when taking a look at my files solver1_0000.out solver1_0001.out spring.hm
  3. okay thank you for the answer. I tried to implement your suggestions in a simple, single spring element and compared the function based spring to a linear spring (putting K and C in). The input of the spring stiffness via the Force Displacement function worked fine and I got the same result as with a constant factor K! Then when trying the same thing with the damping function, the solver tells me after 4 iterations that the maximum energy error is reached and the runs has been killed. I don't know what I am doing wrong 'cause I am assuming for C= 4 Ns/mm and my function's abscissa goes from 0mm/s to 500mm/s and the ordinate goes from 0 N to 2000N which results in a slope of 4 Ns/mm and should be equal to the constant C... Where is my mistake there? And another question to the spring: How can I implement different Force-Displacement curves for loading and unloading the spring?
  4. Hey guys, I'm looking for some help! I'd like to set up a shock absorber model for a dynamic calculation with RADIOSS as a 1D element. How can I do this? The shock absorber I would like to simulate consists of two parts; a spring and a damper element. Of those two parts I have also characteristic curves available, but how can I input them? (The two curves are attached below) The red line is the curve for the damper itself whereas the green line is just for the spring. Really appreciate your help!
  5. Okay, ahm I would need to apply a line load (lift) on the wing beam element using an equation for the elliptical distribution of the load. In Optistruct solver this would not be a problem but in Radioss I don't find any command for doing this... The load is dependent of the angle of attack, which is simplified the angle between the wings beam and an horizontal line, which you can also see in the picture below. This angle is changing permanently during touchdown, which makes it essential that this angle gets measured out of the model after each calculation step and put again in the equation for the lift distribution, so that angle and lift get "updated " after each step of calculation... I hope that I made it a bit clearer now
  6. Hey, I have got quite a tricky task to fulfill with Hypermesh and I don't know if this will work generally... So I am simulating an aircrafts landing shock. The aircraft consists of Beam Elements for the structure and Shell Elements for the tires. The Beams are lines with an added line mesh. I want now to apply aerodynamic loads onto the wings with a specific elliptical lift distribution. For this purpose I have a position dependent (wing span) equation but how can I apply line loads in the Radioss environment as a load collector? (I checked out the Cload but there I can only put time dependent curves in...) If this works somehow, the created lift is dependent of the angle of attack, which is the angle between the wing and an horizontal line. To achieve this, this angle should be measured out of the model after each calculation step and then put again into the lift equation to achieve a new lift value which is then used for the next calculation step... Is this somehow possible? Would be so happy if you could help me! (With the attached files you can have an overlook of the simplified aircraft structure...)
  7. thanks I thought that there is an air resistance but, as it seems logic, there is none, so they have to accelerate the same...little mischief by me... nevertheless thank you
  8. Hi, I wanted to check out how to work with Beam3N Elements. So the simulation is working, with two different, but simple, beam elements. The question I have is following: I have applied a mass with the Admas Manager to one of the beams, but when simulating a drop of a specific height the two beams accelerate uniformly. But the beam with the added mass should be accelerating way faster than the one with out a mass... And the other beam has, when looking to the mass calculation zero total mass, but is still falling down to ground... (By the way which unit does the added mass have? I assumed kg...) How can I fix this? Thank you for helping (Attached the file below) beam1.hm
  9. hey again, I don't really want to get on your nerves but I still don't get it working right... Always this descending pressure curves are annoying me, I really don't know what I'm making wrong... Maybe you could show me step by step how to set up a realistic tire simulation with an appropriate pressure curve at the end? I have tried everything and you are kind of my last chance to get it right... Thank you in advance!
  10. Okay, yeah your pressure plot is perfect, but when I'm running your attached files I get the same pressure curve as I got before The pressure never gets constant as shown in your plot above... May you could attach the solver files one more time? Thanks for checking some other information about this topic !
  11. Thank you for the quick response! The pressure is, I'm afraid, still decreasing permanently after impact... Maybe you have some other advise for me?
  12. Hey guys, I'm trying to simulate a tire bouncing off a rigid wall. I defined a monitored volume with air properties and an external surface, which is the tire. The external pressure is 0.1 MPas and the external is 0.2 MPas. The solver runs fine but the funny thing is that the pressure of the monitored volume is decreasing permanently (also below 0.2 MPas, like there would be a leak somewhere...). In the attached picture you see the peak where it hits the ground but then, instead of normalizing the pressure to 0.2 MPas, it's getting less and less. The volume of the monitored volume gets bigger, therefore the product of p*V to the power of gamma stays constant. Why is this happening? How can I change this? Is there a more realistic way of modeling/simulating a tire? (Also the Hypermesh file is attached) Appreciate all of your answers, thanks (; tire_new.hm
  13. Hey Guys, I want to simulate 2 pipes connected with a joint (spring with property P45KJoint2 connected with Rbody 1D elements at each end) under gravity force and a initial velocity falling on a rigid wall (ground). Whenever starting Radioss the solver says following: ERROR ID : 274 ** ERROR IN RIGID BODY DEFINITION (INERTIA) The model checker says that under error all points are checked, just at the warning section it says :"Rbody ID is different from Masters ID" with a cross...How can I get that checked too? I also attached the file, so that you can have a better look at the issue. Please be so kind to help me pipes.hm
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