A random dynamic load identification method based on perturbed stochastic finite element

Abstract

The invention provides a stochastic-dynamic-load identification method based on perturbation stochastic finite elements. Multiple modal tests under the same condition are carried out on a structure with an uncertain parameter, and uncertainty stiffness, mass and a damping matrix thereof are calculated; the uncertainty stiffness, the mass and the damping matrix are expanded; a Green's-function matrix is calculated; an uncertainty dynamics model based on the perturbation stochastic finite elements is established; stochastic displacement response samples of the structure which is under the actionof stochastic dynamic loads and has the uncertain parameter are measured; a random displacement response sample mean-value is used to identify a mean value of the stochastic dynamic loads on the structure; an approximation value of stochastic displacement response covariance caused only by the randomness of the dynamic load is calculated; and statistical features of the stochastic dynamic loads are identified and acquired. By using the method of the invention, dynamic response, a structural system and uncertainty of the dynamic loads can be simultaneously considered, the actually measured dynamic response samples can be used to identify and acquire the statistical features of the structural dynamic loads, rich dynamic-load information can be provided for the engineering structure, and safety evaluation and optimization design of the engineering structure are further facilitated.

Description

technical field [0001] The invention relates to an indirect identification method for dynamic loads, in particular to an identification method for random dynamic loads. Background technique [0002] Dynamic loads on engineering structures are crucial to the design and safety assessment of structures. In many cases, the external loads on some engineering structures are difficult to obtain through direct measurement methods, such as the aerodynamic loads on the aircraft during flight, the wind and wave loads on the offshore platform, and the contact loads between the wheels on the vehicle and the ground, etc. Therefore, using Obtaining dynamic load information indirectly by measuring the dynamic response of the structure has become a widely used technology, also known as the dynamic load indirect identification technology. [0003] Most of the current indirect identification methods for dynamic loads do not consider the uncertainty of structural system parameters. Using deter...

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Problems solved by technology

However, the dynamic loads on the actual engineering structures, such as wind loads, seismic loads, aerodynamic loads, and noise loads, often present random characteristics. Statistical characteristics of the actual dynamic load, it is easy to "over-design" or "under-design" due to incomplete understanding of the dynamic load information in the structural design process; on the other hand, the engineering structure itself due to manufacturing and measurement errors and the material The discrete nature of the structure makes the system parameters of the structure sometimes not suitable to be described by a definite value, and the uncertainty of the system parameters will be distorted or even wrong if the uncertainty of the system parameters is not considered.

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