Mechanical part sine frequency sweep vibration fatigue damage estimation method

Abstract

A mechanical part sine frequency sweep vibration fatigue damage estimation method comprises the following steps: firstly, establishing a dynamic analysis model of a mechanical part system by using a finite element method to obtain mass, damping and stiffness matrixes of the system, then converting the dynamic analysis model of the system into a modal model, and performing modal analysis to obtain a modal stress matrix; representing the system by using a state space under the modal coordinate system, and obtaining a state space matrix of the system under the modal coordinate system; and sequentially calculating to obtain a frequency response function of the system under the modal coordinate system, a system frequency domain response spectrum under the modal coordinate system during sine frequency sweep vibration and a stress frequency domain response spectrum of the system; and then calculating the alternating stress amplitude and the cycle index in a small time interval, obtaining the fatigue damage cycle index from the S-N curve of the material according to the alternating stress amplitude, and finally estimating the fatigue damage of the mechanical part according to the Palmgren-Miner theory. The method is high in calculation efficiency, the accuracy is equivalent to that of a classical time domain method, and the fatigue damage of the mechanical part can be estimated more accurately.

Description

technical field [0001] The invention relates to the technical field of mechanical design, in particular to a method for estimating fatigue damage of mechanical parts by sinusoidal frequency sweep vibration. Background technique [0002] Fatigue is the main cause of failure of mechanical components. The basis for analyzing the failure of mechanical components is to correctly estimate the fatigue damage of mechanical components. The existing fatigue damage estimation methods are mainly time domain method and frequency domain method. Using the time-domain method to estimate the fatigue damage of mechanical parts is computationally intensive and time-consuming, and the efficiency is low. Using the frequency domain method to estimate mechanical fatigue damage requires less calculation and takes less time, especially when the research object is a complex finite element model. Using the power spectral density method can quickly obtain the frequency response of mechanical components...

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Problems solved by technology

[0004] In order to overcome the deficiencies in the above-mentioned prior art, the object of the present invention is to provide a method for estimating fatigue damage of mechanical parts by sinusoidal frequency sweep vibration, which is used to estimate the sinusoidal Frequency-sweeping vibration fatigue damage overcomes the time-domain method’s large amount of calculation and serious time-consuming defects, and greatly improves calculation efficiency; enriches the fatigue damage estimation method of mechanical components based on the frequency-domain method, with high calculation efficiency and accuracy comparable to classical time The domain method is comparable, and can estimate the fatigue damage of mechanical parts more accurately, and then use it for vibration fatigue failure analysis of mechanical parts

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