A Method for Estimating Vibro-acoustic Fatigue Life of Metal Structures with Uncertainties

Abstract

The invention discloses an estimation method for a sound vibration fatigue life containing an uncertain metal structure.According to the method, firstly, a finite element analytical model of a metal structure is established, the uncertain effect of material and structure characteristic parameters under finite sample conditions is considered, and a systematic transfer function is obtained based on the frequency response analytical theory; secondly, according to the characteristics of random noise loads, a mean square root response and stress power spectral density function (PSD) of displacement and stress of all key nodes is obtained through an SRSS method for typical broadband steady ergodic random noise loads; thirdly, in combination with a Dirlik model, an interval uncertain propagation second-order Taylor series expansion method and an analytical method for vibration fatigue within a frequency domain, the relation between a rain flow amplitude probability density function and the power spectral density function is set up; finally, the Miner linear accumulative damage theory is used for obtaining an interval range of the sound vibration fatigue life containing the uncertain metal structure.Dispersity of the structure and material parameters is taken into full consideration during calculation of the structural life excited by typical random noise, and therefore the obtained fatigue life is more reasonable.

Description

technical field [0001] The invention relates to the technical field of metal structure noise vibration fatigue, in particular to a method for estimating the dynamic response of structures to random noise loads and the acoustic fatigue life under the consideration of uncertainty. It is suitable for the efficient prediction of acoustic fatigue life of various structural types under typical complex noise loads, and provides assistance for the design of engineering anti-acoustic fatigue structures. Background technique [0002] The essence of the effect of noise load on structures is a spatially distributed dynamic random pressure load with certain frequency distribution characteristics. When the sound pressure level exceeds 140dB, it can produce a certain distributed stress response on the structure, especially when the frequency distribution characteristics of the noise are coupled with the dynamic characteristics of the structure it acts on, the structure will produce a signi...

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Problems solved by technology

There are many limitations in the traditional acoustic fatigue life estimation. For example, when considering the dynamic stress effect, only the low-order frequency is considered, and some only consider the first-order natural frequency. There is a certain error in the effect caused by the load with a wide frequency distribution and high energy. ; In the preliminary design, the designer needs to know whether the material and structure type used by the object are the same as the existing curve. If they are the same, the life can be obtained by citing the acoustic fatigue test curve of the specific structure type and material after obtaining the root mean square value stress. , but it is not the same, it is necessary to re-design the structural parameters, and use the existing curves to perform equivalent conversion and empirical correction of the results. This is a large workload and low precision; the RMS life curve of specific structures and materials is very scarce. , the number of existing ones is small, and a large amount of experimental data support is needed

[0004] In addition, the initial defects and damage caused by the manufacturing process and material heterogeneity are inevitable, and will continue to develop, spread, and spread inside the structure during the long-term service in the future, seriously affecting the mechanical behavior and safety of the structure.

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