Moses Ship Launch Simulation

Hi,

I am currently working on Ship Launch Simulation, I had created Ship Geometry model and Ship Launch model and Prepared .dat file from MOSES Modeller. 

I find most of the manuals and tutorials are referring to Jacket Launch. 

I am trying to connect the two bodies using Assembly lleg command but it seems that It shows the model cannot be displayed.

The two bodies do not connect each other i.e Ship and Launch way. 

1. Does moses can able to launch bodies that is modeled using the Modeller?

2. The Launchway body modelled is actually representing the Launch jetty rather than barge what could be the steps involved. Do I need to change the change the operation design as Barge where I need to change the angle as 4 degree.

3. The Launching is occuring with the force of gravity so no winches will be involved.

4. Do I need to include the structural property of the ship like girders and web girders for all the frames inside the hull. Is structural class is required to create for this analysis?Two Bodies (One Ship hull & LAUNCHWAY)

5. The Tpin command is used to define the parameters at the end of the launching barge. In this scenario, we have launchway that is inclined at 4 degrees as shown in the picture above. Kindly suggest me what would be the best possible location of -tpin. The inclination starts at the first 5 m. Total length of the launchway is 100 m, Total length of the ship is 100 m.

I am stuck with this tried tutorials and manual files, example. 

awaiting for reply,

Thanks

PV

Parents
  • Hi PV,

    It is difficult to provide a response without looking at your files, but I will try my best to answer your queries.

    1.) Yes, you can model the body either in MOSES modeler or via the PGEN command, and both can be used in MOSES analysis.

    2.) In this case, you can try modeling the "launch jetty" as body fixed in space. The simplest way to achieve this is by using the -ignore x y z rx ry rz option in the &describe body command. Now, when you define the launchway points on the "launch jetty" along the skidway, it will have a tilt of 4 degrees as per your geometry.

    3.) This should be fine. You don't need to use the -winch option in the LAUNCH command.

    4.) That will depend on the purpose of your analysis. If structural results are important, then you can model them. Otherwise, if you are only looking at the barge flotation/stability, then you don't need to model structural attributes.

    5.) What you are trying to simulate is not a traditional launch assembly but instead launching a barge from an inclined jetty. This means there is no "rocker arm" for which the -tpin option is used to define the "rocker arm". In this case, you can define the -tpin at the corner point of the jetty. Basically, the Xp, Yp, and Zp points will be at the top left corner of the jetty. The "TPRIDEP" and "DIST" can be set to a very small number, let's say 0.1. The max angle can be set to 90 degrees. Basically, you are moving the -tpin to the corner of the jetty.

    Please let me know if the above is clear. In case you still have questions, please upload your files here or you can send them to me at rahul.kanotra@inventocean.com for me to have a look and assist you better.

    Thanks,

    Rahul 

  • Hi Rahul,

    Thank you very much, Yes I will send my files to you.Your answer did help understand the scenarios.

    1. I have modelled both my ship and Jetty in modeller and exported as standard input file for moses. 

    2.Thanks, yes I have used -ignore when I am describing the body as per manual. This is the point where I struggle. My Hull is not able to get seated or fixed on the Launchway in tilted position when I implement "Assembly lleg" code. I tried &instate command with -move command, Since both my hull and launchway are bodies, it does not working as defined.

    3. Thanks, I will remove my -winch option

    4. My sole purpose of analysis is only flotation and stability, It is to check the position and trajectory of the hull from launch till the hull attains equilibrium.

    5. In this scenario you are suggesting the rocking to be located at the beginning of the jetty i,e exactly at the position where the inclination begins. Lets say my inclination starts when x =5 m and end of the jetty is at x =100. then my -tpin command will be -tpin 0.1 5 2.8 2. 

    I will send my files for better clarity.

    Thanks again for your reply. 

    Thanks,

    PV 

  • Hi PK,

    2.) When you define the points on the launchway, I hope you have defined them along the slope. This means that the elevation of the first point (starting of the slope) will be higher than the elevation of the last point (end of the slope). At the beginning of the simulation, the line joining the launch_way points on the vessel and the line joining the jetty points should coincide.

    5.) No, what I meant is that you will define the -tpin point at the end, specifically at x=100. There is no rocker arm in this case, and by defining it at the end with a negligible arm, we are disregarding its use here.

    Sure, please send me the files, and I can take a better look at them to assist you.

    Thanks,

    Rahul

  • Hi Rahul,

    Thanks for the reply, I have sent the files across,

    I have tried the code as per the suggestions.

    2. I have defined the points in launchway along the slope. The length of the vessel is 100 m and length of the launchway jetty is 113 m. I have created the points exactly similar to the starboard and port side of the vessel. Are you suggesting that I should create 100 points each on ship and 100 points on Launchway jetty.

    5. If i remove the -tpin comment I find the vessel not aligned with the Launchway jetty. I have sent a file to you for better view.

    The vessel is not exactly aligned in angle orientation as per the code. 

    Can we try any flexible connector class between the hull and launchway other than Assembly lleg.

    Awaiting for your valuable suggestions and guidance.

    Thanks,

    PV

  • Dear PK,

    Please check your email. I have reviewed your files and sent a response to you.

    Thank you,

    Rahul

  • Hi Rahul,

    Thanks again. Sure I will work on the comments and update.

    Thanks,

    PV

Reply Children
No Data