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  1. Ionut Cosmin

    How to determine the environmental loads for a CubeSat based on the launcher?

    Hi everyone, I am trying to understand how to properly evaluate the environmental loads (accelerations, lateral and axial frequency limit, sine vibration profile, random vibration profile, shock, etc) that will need to be used in the structural analysis and validation of a CubeSat based on a...
  2. Ionut Cosmin

    How to derive the first natural frequency requirement of a subassembly?

    Hello all, I am trying to determine what should be the first eigen mode frequency for a subassembly if the requirement is known for the assembly. For example, let' say I have a robotic arm which has a requirement that the first natural freq should be higher than 70 Hz. On this arm I have an...
  3. Ionut Cosmin

    Venting analysis on satellite payload/electronic box

    Hello everyone, I have to do a venting analysis on an electronic box that will go into space. My question is if anyone has ever performed such an analysis and can give me some guidelines? I am wondering if there are any formulas that I can use and check the dimensions of the venting holes. I...
  4. Ionut Cosmin

    Strain gauge position based on FEM?

    Hi all, I am trying to determine the best position for strain gauges on a milled aluminum aviation part that will be tested. I am checking the max principal strains in the FE model and I am wondering if there are any rules, guidelines, or best practices when looking over the FEA and determining...
  5. Ionut Cosmin

    Can you specify spring stiffness and damping as a curve instead of a single value ?

    I am wondering if it is possible to specify the stiffness and damping coefficients as curves ? I have a gas damper in real life on which the compression force depends on the velocity of the piston rod, so my values for stiffness and damping are variable. Can I model this with a translational...
  6. Ionut Cosmin

    Optimize spring damper stiffness and damping coefficient

    Hello, I am trying to simulate an impact between a spring damper attached to a body and the ground. I have attached an image to better understand . As you can see, a spring damper is attached with 2 bodies, one with a bigger mass and one with null mass (used only for contact purpose). As you...
  7. Ionut Cosmin

    PARAM, INREL, -2 with RIGID=LAGRAN problem ?

    Hi all, I am trying to run an analysis of a satellite which involves a thermal load (temp on each node). The model contains multiple RBE2 and CONM2 to simulate the connection of equipment mass to the structure. I am using a CTE for each RBE2 and also RIGID=LAGRAN, as stated in the nastran docs...
  8. Ionut Cosmin

    Problem with .dat output with Dytran preference ?

    Hi all, I am having some problems with Patran. I have loaded the Dytran Analysis preference with the load_mscdytran() command, I have created the model and when I want to run an Analysis (with Translate option, not a Full Run), to create the .dat file, I don't get anything. The db closes for a...
  9. Ionut Cosmin

    Structural analysis of a rocket ?

    Hello everyone, I am curious to know if anyone knows what are the steps performed in the structural analysis of a rocket ? What are the most important parts and what type of analysis are performed on them ? If anyone has worked on building rockets for NASA or other space agency, maybe they...
  10. Ionut Cosmin

    Questions about a finite element modeling situation ?

    Hello everyone, I am currently modelling a part with finite elements in Patran, and I have encountered a small problem. Basically I have a part that is made out of several hollow beams and solid plates, and I have modeled everything with shell elements. The problem occurs at 4 beams that run...

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