Identify the spatially-correlated random fluctuating pressure on structure from strain data

Abstract

Distributed load information is essential for the design and monitoring of aerospace structures. A frequency domain method for the identification of correlated random fluctuating pressure is proposed in which structural responses acquired from limited strain sensors are used. The spatially-correlated power spectral density function of the random fluctuating pressure on the structure is firstly represented by Legendre polynomials w.r.t. the spatial distance multiplying their corresponding frequency-dependent coefficients. Secondly, the transfer matrix is obtained by the stochastic response analysis using distributed load in the form of Legendre polynomials. Then, the coefficients in the power spectral density function model of the pressure are identified by inversion of the transfer matrix together with a modified regularization technique. Finally, the random fluctuating pressure load is reconstructed by the superposition of the identified coefficients multiplying with Legendre polynomials. Numerical simulations on a simply-supported plate subjected to correlated stochastic distributed loads are conducted to verify the proposed method. Factors that may influence the accuracy of identification results are also discussed. To test the performance of the proposed method on complex structures, the gust-induced pressure load on a 3D wing structure is further identified using the proposed method. Results show that the proposed method is capable of identifying the correlated random fluctuating pressure on aircraft structures.