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Time History Post Processing Results

Dave McD
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In a time history analysis, can AutoPIPE report the maximum stresses from a user specified time range? For example, between time 2 seconds and 4 seconds of a 6 second analysis? From the TH post processor, we can get the displacements and loads but not stresses

Background: We are doing a time history analysis for a PD pump discharge line where the time history loads are extracted from an AFT Impulse analysis. Since the loading throughout the system is essentially sinusoidal, there are several bend locations where there is a high load at time zero in the TIH file. This is interpreted as an instantaneous load resulting in higher than normal displacements and stresses in the first few seconds of the analysis. We would like to determine the maximum stress when the system settles out after about 2 seconds into the analysis.

AutoPIPE v9.6

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    Dave,

    This seems to be an interesting scenario. Unfortunately, I think it is currently not possible for AutoPIPE to report maximum stress from a user specified time range. Do you think setting the Start time on the Time History Location dialog for each point would get you your desired analysis results? I assume that you do want to take in to account the applied initial loading, however, you are interested in the highest stress discarding certain time sections. Let me know your thoughts.

    I think working around this would be a tiring process i.e. trying to export moment values using TH post processor in each direction and then trying to manually calculate the resultant moment value for a time range to be used in stress calculations.

    If setting the Start time is not your intended solution, can you log a service ticket for an enhancement with your suggestions on how best this could be achieved? Do you believe that this is something which many other users would be interested in?

    Thank you for your time.

    Regards,
    Bilal Shah

    Regards,

    Bilal Shah

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  • 0 Offline
    Dave,

    This seems to be an interesting scenario. Unfortunately, I think it is currently not possible for AutoPIPE to report maximum stress from a user specified time range. Do you think setting the Start time on the Time History Location dialog for each point would get you your desired analysis results? I assume that you do want to take in to account the applied initial loading, however, you are interested in the highest stress discarding certain time sections. Let me know your thoughts.

    I think working around this would be a tiring process i.e. trying to export moment values using TH post processor in each direction and then trying to manually calculate the resultant moment value for a time range to be used in stress calculations.

    If setting the Start time is not your intended solution, can you log a service ticket for an enhancement with your suggestions on how best this could be achieved? Do you believe that this is something which many other users would be interested in?

    Thank you for your time.

    Regards,
    Bilal Shah

    Regards,

    Bilal Shah

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  • 0 Offline in reply to Bilal Shah
    Bilal,
    Thanks for your reply.
    Setting the start time at each point does not work. It's not like water hammer or slug flow where the unbalanced force travels down the pipe and the load starts rising then dropping at different times at points along the pipe run. We have an oscillating load and at any particular time it's likely that a maximum load will be at time 0 or time step 1.

    It looks like until the post processor is improved we can't get what we want directly and I don't think we should export the moments and forces to a CSV file and calculate the code stresses by hand (Excel). That's what AutoPIPE should do. (Unless there is a spreadsheet available from Bentley where we can that?)
    I would think that others would benefit if this feature is available.

    The same is also true for finding the load on a support at a specific time in the analysis. Currently that has to be done manually by exporting the i and j loads at a point to a CSV file and doing the math in Excel.


    Dave
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