{"id":365427,"date":"2024-05-03T14:01:41","date_gmt":"2024-05-03T14:01:41","guid":{"rendered":"\/forum\/forums\/topic\/connection-stiffness-ansys-aqwa\/"},"modified":"2024-05-03T14:01:41","modified_gmt":"2024-05-03T14:01:41","slug":"connection-stiffness-ansys-aqwa","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/connection-stiffness-ansys-aqwa\/","title":{"rendered":"Connection Stiffness Ansys AQWA"},"content":{"rendered":"

Hi everyone,<\/p>\n

I’m currently working on simulating the response of 4 floating blocks connected to each other with hinged joints subjected to regular waves of amplitude1m, as illustrated in the attached image. My objective is to simulate the heave RAO [m\/m] for all the 4 bodies at 0.7 rad\/s using frequency domain analysis with hydrodynamic diffraction. Ultimately, I need 4 Heave RAO [m\/m] values for the 4 blocks at 0.7rad\/s<\/p>\n

However, I’m encountering difficulties in doing the hydrodynamic diffraction simulation due to the connection stiffness matrix. I understand that the hinge connections are only considered in hydrodynamic response analysis and I need to specify the connection stiffness as a 6×6 matrix for hydrodynamic diffraction analysis.<\/p>\n

For the hinged connection in the hydrodynamic response analysis, I would need to define the rotational stiffness about the y-axis which I obtained using a research article as 6.27e9 Nm\/rad. However, this is just a single value and the connection stiffness is a 6×6 matrix.<\/p>\n

Therefore Here are my questions:<\/p>\n

    \n
  1. What does the connection stiffness signify? What do the notations (X,Y,Z,RX,RY,RZ) signify? I mean I know that they represent the translational and rotational motion of the connection but how do I read and the matrix as there is no sufficient information in the theory manual of aqwa?<\/li>\n
  2. \n

    How can I translate the single rotational stiffness (6.27e9 Nm\/rad) to the connection stiffness as a 6×6 matrix to resemble a hinged joint?<\/p>\n<\/li>\n

  3. \n

    Alternatively, if I opt to deduce the heave RAO using only hydrodynamic response analysis as I can fully define my hinged joint, how can I obtain the heave RAOs for each of the 4 connected bodies at 0.7 rad\/sec? Currently, when I plot the heave RAO, the plot displays values in [m] instead of [m\/m]. Additionally, in a time domain analysis, the heave RAO appears as a function of time, unlike the frequency domain analysis where I get a single RAO value for a particular frequency. So how do I get a single RAO value [m\/m] for each block at 0.7rad\/sec using HR analysis?<\/p>\n<\/li>\n<\/ol>\n

    Any assistance or guidance on these matters would be greatly appreciated.<\/p>\n

    Thank you.<\/p>\n

    <\/p>\n","protected":false},"template":"","class_list":["post-365427","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t