General Mechanical

General Mechanical

A problem in “tabular loading” of the imported body force density.

    • HiwaGhaffari
      Subscriber

      Hi.
      I am doing a transient analysis. I want to apply an impulse force obtained from a Maxwell 2D transient analysis to the object. Figure-1 shows the diagram of force changes in terms of time (black curve). Since I have not found a way to apply this force, I have approximated it as a red curve. That is, the extremum points are connected linearly.
      Importing force to the mechanical environment is done through Maxwell's direct link. 4-time steps are defined so that in each of them, the value of one of the force extremums is applied, then by ramping them, the said linear curve is obtained.
      But, I could not apply a ramp with a negative slope to the force, and ramping is done only in an upward direction. Figure-2 shows the final state of the force curve, which is different from the desired one. 
      Can someone please guide me to fix this problem?

    • Aniket
      Ansys Employee
      1. Are you applying this as an imported load?
      2. If yes, I am not sure if datapoints on graph above matches with the one in the tabular data below

      -Aniket

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    • HuiLiu
      Ansys Employee

      Could you clarify more about the workflow? If the force is mapped directly from Maxwell to Mechanical you shouldn't need to change any setting to alter the imported load value. Does the force plot look like what you show in the first figure in Maxwell?

    • HiwaGhaffari
      Subscriber

      Hi Aniket.

      1. Yes, I have imported the surface force density into the Transient Structural analysis and applied it to the target surface body (Electromagnetic and mechanical analysis both are in 2D mode.  
      2. This problem exists. When the body force density is imported into the mechanical, the maximum and minimum force values are located at times that are slightly different from the extremum points of the diagram. In this problem, the maximum body force density is obtained in time 80 us, while the graph shows the first maximum point at about 90 us. I have defined the time steps as equal to the corresponding times of the maximum and minimum of the imported body force density values. 
      3. Maybe it would be better to ask my question like this: why when the amount of force at 80 microseconds is linearly connected to its value at 205 microseconds, the slope of the line is upward, while the amount of force at 205 microseconds is lower? The slope of the line should be downward.

       

    • HiwaGhaffari
      Subscriber

       

      Hi HuiLiu.

      As far as I know, when force density is imported from a transient analysis in Maxwell into Mechanical, it is necessary to specify a specific time to import the force value at that time. That is, it is not possible to import force changes (in terms of time) in the entire analysis time, as the curve shows.

      So, the only way I had was to approximate the graph linearly. In this way, the times related to the extremum points can be determined for importing the force density at them. Next, if the ramp can be correctly determined to load the table values in time steps, the linearized graph will be obtained.

       

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