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. 2025 May 26;15(1):18441.
doi: 10.1038/s41598-025-03353-5.

Estimation of natural frequency for nonlinear mechanical retention of printed circuit board

Anurag Arjunan  1 , Arun Babu  2
Affiliations

Estimation of natural frequency for nonlinear mechanical retention of printed circuit board

Anurag Arjunan et al. Sci Rep. .

Abstract

Vibrational performance for a structure, in majority of the cases, is estimated/ predicted using frequency domain solvers. Linearity and Time-invariance are imposed onto the structure for solving in frequency domain. In this research, vibrational performance of two mechanical mounting methods for a hot-swappable electronic PCB have been analyzed and experimented upon, in the range of 7 to 300 Hz. Natural frequencies were first estimated using Linear Modal Analysis and the response up to 500 Hz was obtained through Harmonic analysis. The resonance was predicted at 440.8 Hz for both the mounting methods. Experiments were conducted on both the setups to determine the natural frequencies through a sinusoidal sweep. Resonance was observed at 110 Hz and 193 Hz for Setup-I & II, respectively. These large deviations led to investigation on factors which played a major role in shifting the frequencies, arising out of both mounting methods. Limitations of linear modal analysis were highlighted. A method (computational + FFT) is devised for estimating the natural frequencies in which time domain response was coupled with Fast Fourier Transform (FFT). Validation against the testing showed that the suggested method predicted the non-linear natural frequencies with a significantly improved accuracy (Nominal deviation < 2%) for both the setups.

Keywords: Clearance effects; FFT; Natural frequency estimation; Non-linearity; Spring finger retainer; Transient response.

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Conflict of interest statement

Declaration. Competing interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
(a) Construction details of PCB mounting (Ansys spaceclaim); (b) MicroTCA connector (Solidworks 2022).
Fig. 2
Fig. 2
(a) Setup-I: PCB mounted in clearance slots; (b) Setup-II: PCB mounted in card retainers (Solidworks 2022).
Fig. 3
Fig. 3
(a) Base excitation applied to the setup; (b) Meshed model of the setup (Ansys mechanical 2024 R1).
Fig. 4
Fig. 4
(a) Mode shape for setup-I (443.9 Hz); (b) Mode shape for setup-II (439.57 Hz).
Fig. 5
Fig. 5
(a) Location of response measurement (Ansys mechanical 2024 R1); (b) Frequency response of setup-I & II.
Fig. 6
Fig. 6
(a) Construction of the experimental setup; (b) Shaker table.
Fig. 7
Fig. 7
(a) Slotted card guide (setup-I); (b) Card retainers attached to card guide (setup-II).
Fig. 8
Fig. 8
Resonance search by sinusoidal sweep for (a) Setup-I; (b) Setup-II.
Fig. 9
Fig. 9
Computational modelling of (a) connector pins (cross-sectional view plane X–Y); (b) Clearance between PCB and slot in Setup-I (cross-sectional view plane Y–Z); (c) Fingers of retainer. (Fig. 9. (a), (b), (c) from Ansys spaceclaim 2024 R1).
Fig. 10
Fig. 10
(a) Impact defined at base nodes; (b) Nodal selection for setup base (Ansys mechanical 2024 R1).
Fig. 11
Fig. 11
Transient response of PCB upon base impact for (a) Setup-I; (b) Setup-II.
Fig. 12
Fig. 12
FFT data from transient response for (a) Setup-I; (b) Setup-II.
Fig. 13
Fig. 13
Frequency response function of the impact load.
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References

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