# Random Vibration Fatigue Life Analysis of Airborne Electrical Control Box
###### Abstract  
To study the influence of random vibration on the fatigue life of airborne equipment, an aircraft electrical control box was selected as the research object. First, finite element software was used to model the dynamics of the airborne electrical control box to investigate its mode frequencies. The accuracy of finite element simulations was verified by performing mode experiments. Second, the mode superposition method was used to analyze the flight direction (X axis), side direction (Y axis), and altitude direction (Z axis) random vibration responses of the electrical control box. The analysis results were combined with the Miner linear cumulative damage criterion and the Gaussian-distribution Steinberg method to estimate the fatigue life of the electrical control box in the three directions. Finally, the calculation results were verified by performing the random vibration durability test on the electrical control box. The finite element mode analysis results show good agreement with the vibration experiment results, and the maximum error is 13.4%, indicating that the finite element model established in this paper is acceptable. The fatigue life of the electrical control box in the three axes meets the user requirements, and random vibration along the side direction (Y axis) has the greatest impact on the fatigue life, which is consistent with the results of the actual experimental data. The research method can be extended to predict the fatigue life of other airborne equipment and thus has practical significance for structural design and reliability analysis of airborne equipment. electrical control box; random vibration; fatigue analysis; Steinberg method; test validation 2022220219  
developed. [PERSON] et al. [4] proposed a spectrum estimation method for estimating the fatigue life considering the high-cycle fatigue state. By using the model proposed by [PERSON] and [PERSON] [5] as an example, two types of multi-axial fatigue failure criteria were established, and the two groups of test data were compared with the calculation data. Under multi-axial random loading, when the appropriate failure criterion is selected, the calculated fatigue life exhibits a good correlation with the test results. [PERSON] et al. [6] presents a new algorithm to implement the Carpinteri-Spagnoli-Vantadori (CSV) multiaxial fatigue criterion for random loading. By calculating the exact expressions of stress spectral moments in every rotated plane, the maximum variance and expected maximum peak of normal/shear stress can be calculated directly, thus shortening the calculation time. [PERSON] et al. [7] proposed an approximate fatigue damage model based on the Gaussian broad-band model by using data processing, time analysis, regression analysis, and other methods. This method summarizes four probability density functions and introduces correction factors. The experimental results showed that the results obtained using this method are very close to those obtained using the rain flow method. [PERSON] et al. [8] established an accurate parametric finite element model and obtained mode frequencies and shapes by solving dynamics equations of aviation airborne equipment. [PERSON] et al. [9] proposed an algorithm that integrates Karhunen-Loeve expansion (KLE) and finite element method (FEM) to perform the random vibration analysis of complex dynamic systems excited by stationary or non-stationary random processes. [PERSON] et al. [10] proposed a method combining random vibration spectrum analysis, dynamic strength reliability theory, and sensitivity analysis. The dynamic strength reliability and parameter sensitivity of the aircraft fuel pipeline system are analyzed using this method. This method can also be used for the dynamic strength reliability evaluation of engineering structures. In this study, the fatigue life of an electrical control box on an aircraft under random excitation was investigated. First, the finite element method was used to analyze the random vibration response of the electrical control box.