O.B. Oleynikov1, I.N. Dubovik2

1,2 PJSC «Radiofizika» (Moscow, Russia)

1,2 Moscow Aviation Institute (National Research University) (Moscow, Russia)

1 captain_oleg@mail.ru; 2 dubovig@mail.ru

At the stage of development and design antenna devices often have requirements for vibration strength and vibration resistance when exposed to random vibrations that may occur during transportation or directly during operation. The main problem is how to calculate antenna structures for random vibration loads without resorting to the economic cost of mechanical testing which can significantly slow down prototype production.

In the proposed method of analysis random vibration is represented as a function of stationary white noise where the spectral components of the input influencing parameter (acceleration) are uniformly distributed over the entire frequency range which can be relatively easily obtained experimentally using modern spectra analyzer using the fast Fourier transform algorithm.

In the specialized software Simcenter Femap, a computational mathematical model of the considered antenna device is developed which includes the structure and a vibration source that transfers the load through the attachment points. This source can be, for example, an armored vehicle experiencing pulsations of the air flow during the movement. An armored vehicle can be represented as a «large mass», 104 to 106 times than the mass of the antenna device itself.

The spectrum of resonant frequencies and vibration modes is determined, the transfer functions H(v) are calculated, which are the largest expected harmonic responses at resonance frequencies v with a unit amplitude.

The acceleration spectral density function ASDIN is specified as a random load P(t) which is applied to the “large mass” of the armored vehicle in the direction of the movement, and is transmitted using rigid links directly to the antenna structure supports. Using the data on the expected harmonic responses of the model elements at resonant frequencies, it is possible to construct the output function of the spectral density of accelerations ASDOUT and conduct a statistical sense of the RMS values of the output parameters of the stress-strain state of the antenna device which cover 99,73% of all possible values.

A method of analyzing antenna devices under the influence of random vibration loads which are presented as random frequency characteristics of vibrations, easily described using white noise functions where the spectral components are uniformly distributed over a wide frequency range. A mathematical model of the antenna device was developed in the program Simcenter Femap with random load P(t) applied to it using the data of the acceleration spectral density input function ASDIN. The system transfer functions H(v) were determined using data of which the acceleration spectral density output function ASDOUT was calculated and performed a statistical sense of root-mean-square RMS output values of stress-strain state of the antenna device.

Oleynikov O.B., Dubovik I.N. Features of setting random vibration parameters in design engineering programs when assessing the strength and stiffness of antenna devices. Radiotekhnika. 2022. V. 86. № 4. P. 12−21. DOI: https://doi.org/10.18127/j00338486-202204-02 (In Russian)

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