Analyze the Results

Review the extracted frequencies and the distortion in the printed circuit board (PCB) after loading. Review the out-of-plane displacement of the components, and the von Mises stress of the PCB near the attachment points of the components.

The effect of external loads is shown by comparing the natural frequencies before and after loading. If the driving frequency is near the natural frequencies of the postloaded PCB, the PCB may resonate and is likely to fail.

In this example, you examine the stress results to determine the quality of the connections securing the parts to the PCB. The heavier parts (the power supply, heat sink, and capacitors) cause more stress and are more likely to displace during loading if the connections securing them fail.

  1. From the Plots panel, under the Step options, select the preloading frequency step.
    Observe the frequencies obtained without loading.
  2. From the Plots panel, under the Step options, select the postloading frequency step.
    Observe the differences in the first 10 frequencies due to preloading, which represents manufacturing defects for the mounting points of the PCB.

    Preloading increases the frequencies as expected.

  3. Save your work.

The figures below show the first mode shapes of the PCB and von Mises stress plots (with and without preloading), corresponding to only the first frequency of each step. The figures show the displacement of the parts on the PCB and the stresses near the connections before and after loading.

Mode Shape of Frequency_step (left) and Frequency_step_postloading (right)

Von Mises Plot of Frequency_step (left) and Frequency_step_postloading (right)

Congratulations, you have successfully completed this example!