Abstract
Fatigue damage in engineering structures is universal. The occurrence of fatigue cracks brings unpredictable hidden dangers to a structure in terms of safety and service performance. Traditional damage identification methods, such as power spectrum analysis, are mostly based on linear elasticity theory that cannot reflect the typical nonlinear characteristics of fatigue cracks and cannot meet the higher requirements of the signal analysis method put forward by current mass detection data. To solve this problem, a numerical model of a cantilever beam with a breathing crack is established in this study. A method for diagnosing fatigue damage is studied by combining bispectral analysis and a statistical normal cloud model, which characterize the nonlinear characteristics of the structure. This method can effectively describe the nonlinear characteristics of the structure and reasonably evaluate the degree of fatigue damage in the structure. The bispectrum-normal cloud model method proposed in this study overcomes the limitations of existing linear damage detection methods in nonlinear damage detection, and can improve the efficiency of signal analysis from a statistical point of view. It has good prospects for structural nonlinear damage assessment.
Highlights
Detection of cumulative damage in a structure in long-term service has been a hot issue in many fields and disciplines [1, 2]
Compared with traditional spectrum analysis or power spectrum analysis, bispectral analysis is more sensitive to nonlinear signals and more suitable for nonlinear damage detection of fatigue cracks
Owing to long term practice and other reasons, damage in structures mostly appears as nonlinear fatigue damage
Summary
Detection of cumulative damage in a structure in long-term service has been a hot issue in many fields and disciplines [1, 2]. Different from power spectrum analysis [3], the application of bispectrum in nonlinearity has been gradually discovered. A normal cloud model is introduced that takes into account the fuzziness and randomness of things in essence, making good use of parameters to express them quantitatively. A cantilever beam model with fatigue cracks is established. Damage to a cantilever beam structure is studied from the viewpoint of statistical probability by using the sensitivity of bispectrum to nonlinear damage and the characteristics of fuzzy region classification of a cloud model diagnosis of injury severity. NONLINEAR CRACK ASSESSMENT METHOD IN BEAMS BASED ON BISPECTRUM-NORMAL CLOUD MODEL.
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