CN103528844A

CN103528844A - Structural damage early warning method based on empirical mode decomposition

Info

Publication number: CN103528844A
Application number: CN201310502632.3A
Authority: CN
Inventors: 刁延松; 任红; 陈家宝; 曹亚东; 孙玉婷; 华盼盼; 徐东锋
Original assignee: Qingdao University of Technology
Current assignee: Qingdao University of Technology
Priority date: 2013-10-23
Filing date: 2013-10-23
Publication date: 2014-01-22
Anticipated expiration: 2033-10-23
Also published as: CN103528844B

Abstract

The present invention relates to the field of structural damage identification, in particular to a structural damage early warning method based on empirical mode decomposition, which utilizes the structural response to construct a vibration transmissibility function, uses the amplitude of the vibration transmissibility function as an analysis signal, and uses empirical mode decomposition technology Obtain the intrinsic mode function, calculate the waveform index of the intrinsic mode function by referring to the definition of the waveform index in the signal waveform processing technology, compare the waveform index before and after the structural damage to judge whether the structure is damaged, and carry out the method of early warning of structural damage. The invention has strong operability, improves processing precision and improves early warning accuracy.

Description

Structural Damage Early Warning Method Based on Empirical Mode Decomposition

技术领域 technical field

本发明涉及结构损伤识别领域，特别涉及一种基于经验模态分解的结构损伤预警方法。 The invention relates to the field of structural damage identification, in particular to a structural damage early warning method based on empirical mode decomposition. the

背景技术 Background technique

由于荷载的作用以及环境的影响，土木工程结构在服役期间会出现不同程度的损伤，若不及时发现并采取措施，将带来灾难性的后果，因此有必要进行结构的损伤预警研究。目前，人们研究并提出了许多结构损伤预警方法，其中，基于振动响应分析的结构损伤预警方法由于无需测量激励，仅利用结构响应对结构健康状况进行评估，更接近实际情况，因此，被认为是一种具有广泛应用前景的方法。 Due to the effect of load and the influence of the environment, civil engineering structures will be damaged to varying degrees during service. If they are not detected and taken measures in time, it will bring catastrophic consequences. Therefore, it is necessary to carry out research on early warning of structural damage. At present, many structural damage early warning methods have been researched and proposed. Among them, the structural damage early warning method based on vibration response analysis is closer to the actual situation because it does not need to measure the excitation and only uses the structural response to evaluate the health status of the structure. A method with broad application prospects. the

目前，利用结构响应构造振动传递率函数，采用经验模分解技术分解结构损伤前后的振动传递率函数，得到振动传递率函数的各阶固有模式函数，通过比较结构损伤前后各阶固有模式函数图形的突变来判断结构损伤与否，从而发出损伤预警。但是，实际操作时噪声不可避免，而噪声也会引起固有模式函数图形的突变，由于没有具体的量化指标，使结构损伤状态的判断带有一定主观性，特别是结构损伤程度较小时，结果可靠性不高。 At present, the structural response is used to construct the vibration transmissibility function, and the empirical mode decomposition technology is used to decompose the vibration transmissibility function before and after the structural damage, and the intrinsic mode functions of each order of the vibration transmissibility function are obtained. By comparing the graphs of the intrinsic mode functions of each order before and after the structural damage Mutations are used to judge whether the structure is damaged or not, so as to issue an early warning of damage. However, noise is unavoidable in actual operation, and noise will also cause sudden changes in the graph of the intrinsic mode function. Since there is no specific quantitative index, the judgment of the structural damage state is somewhat subjective, especially when the degree of structural damage is small, the result is reliable. Sex is not high. the

发明内容 Contents of the invention

本发明针对现在技术中的不足，提供一种利用结构响应构造振动传递率函数，将振动传递率函数的幅值作为分析信号，通过经验模态分解技术获得固有模式函数，参照信号波形处理技术中的波形指数的定义计算固有模式函数的波形指数，通过对比结构损伤前后的波形指数的变化量构造损伤预警指标，进行结构损伤预警研究，结果更为准确直观。 The present invention aims at the deficiencies in the current technology, and provides a structure response to construct a vibration transmissibility function, using the amplitude of the vibration transmissibility function as an analysis signal, and obtaining the intrinsic mode function through the empirical mode decomposition technology, referring to the signal waveform processing technology The definition of the waveform index calculates the waveform index of the intrinsic mode function, and constructs the damage early warning index by comparing the change of the waveform index before and after the structural damage, and carries out the research on the structural damage early warning, and the result is more accurate and intuitive. the

本发明所采取的技术方案是： The technical scheme that the present invention takes is:

一种基于经验模态分解的结构损伤预警方法，包括如下步骤： A structural damage early warning method based on empirical mode decomposition, comprising the following steps:

步骤1：获取结构损伤前后部分测点的加速度响应信号，通过傅里叶变换计算振动传递率函数： Step 1: Obtain the acceleration response signals of some measuring points before and after the structural damage, and calculate the vibration transmissibility function through Fourier transform:

${T T}_{ij ij ((ω ω))} = = \frac{{A A}_{i i ((ω ω))}}{{A A}_{j j ((ω ω))}} - - - - - - ((11))$

式中，A_i(ω)，A_j（ω）为响应信号的傅里叶变换； In the formula, A _i(ω) and A _j(ω) are the Fourier transform of the response signal;

步骤2：将公式（1）所得的振动传递率函数的幅值作为分析信号，通过经验模态分解技术得： Step 2: Use the amplitude of the vibration transmissibility function obtained by formula (1) as the analysis signal, and use the empirical mode decomposition technique to obtain:

$| | {T T}_{ij ij} | | = = {Σ Σ}_{k k = = 11}^{n no} {a a}_{k k} + + {r r}_{n no} ((t t)),, - - - - - - ((22))$

式中，a_k为振动传递率函数幅值的固有模式函数，r_n(t)为余量； where a _k is the intrinsic mode function of the amplitude of the vibration transmissibility function, and r _n (t) is the margin;

由公式（2）可见，经验模态分解将原始信号按一定规律分解为固有模式函数的和，可以认为原始信号的能量被分配到了固有模式函数上。当结构发生损伤时，信号中的能量成分会发生变化，通过经验模态分解后，信号中的能量成分的变化就会在某几阶固有模式函数中显现出来，即某些固有模式函数就会发生明显的变化。 It can be seen from formula (2) that the empirical mode decomposition decomposes the original signal into the sum of intrinsic mode functions according to certain rules, and it can be considered that the energy of the original signal is allocated to the intrinsic mode functions. When the structure is damaged, the energy component in the signal will change. After the empirical mode decomposition, the change of the energy component in the signal will appear in some order intrinsic mode functions, that is, some intrinsic mode functions will be Visible changes occur. the

步骤3：参照信号波形处理技术中的波形指数的定义，定义固有模式函数a_k的波形指数F_k为： Step 3: Referring to the definition of waveform index in signal waveform processing technology, define the waveform index F _k of intrinsic mode function a _k as:

${F f}_{k k} = = \sqrt{\frac{11}{N N} {Σ Σ}_{l l = = 11}^{N N} {(({a a}_{k k (({ω ω}_{l l}))}))}^{22}} / / \frac{11}{N N} {Σ Σ}_{l l = = 11}^{N N} | | {a a}_{k k (({ω ω}_{l l}))} | | - - - - - - ((33))$

式中，N为固有模式函数的点数； In the formula, N is the number of points of the inherent mode function;

从公式(3)可以看出，波形指数F_k与信号幅值的大小无关，波形指数F_k的特点是稳定性较好，因此可以作为表征结构时域响应信号特征信息的参量，进行结构损伤预警； It can be seen from formula (3) that the waveform index F _k has nothing to do with the magnitude of the signal amplitude, and the waveform index F _k is characterized by good stability, so it can be used as a parameter to characterize the characteristic information of the structural time-domain response signal to carry out structural damage analysis. early warning;

步骤4：计算结构损伤前后固有模式函数a_k的波形指数F_k的变化量⊿F_k，考虑到不同的损伤可能引起固有模式函数a_k的波形指数F_k发生不同程度的变化，定义损伤预警指标如下： Step 4: Calculate the amount of change ⊿F _k of the waveform index F _k of the intrinsic mode function a _k before and after structural damage. Considering that different damages may cause different degrees of changes in the waveform index F _k of the intrinsic mode function a _k , define the damage warning The indicators are as follows:

$DI DI = = \frac{11}{M m} {Σ Σ}_{k k = = 11}^{M m} Δ Δ {F f}_{k k} - - - - - - ((44))$

式中，M为选定的固有模式函数的数量； In the formula, M is the number of selected intrinsic mode functions;

通过统计分析定义其门槛值ε，当损伤预警指标DI≤ε时，结构完好，当损伤预警指标DI＞ε时，结构已损伤，发出损伤预警。 The threshold value ε is defined by statistical analysis. When the damage early warning index DI≤ε, the structure is intact. When the damage early warning index DI>ε, the structure is damaged and a damage early warning is issued. the

本发明的有益效果是： The beneficial effects of the present invention are:

本发明的基于经验模态分解的结构损伤预警方法，通过结构损伤前后固有模式函数波形指数的变化量构造损伤预警指标，进行损伤预警，由于使用了具体的量化指标，结果更为准确直观，同时也克服了通过对比结构损伤前后固有模式函数波形的突变进行损伤预警时，遇到的由于噪声的影响，使结构损伤状态的判断带有一定主观性，结果不可靠的问题。可操作性强，提高了处理精度，提高了预警准确度。 The structural damage early warning method based on empirical mode decomposition of the present invention constructs the damage early warning index through the change of the intrinsic mode function waveform index before and after the structural damage, and performs damage early warning. Due to the use of specific quantitative indicators, the result is more accurate and intuitive, and at the same time It also overcomes the problem of subjectivity and unreliable results in the judgment of the structural damage state due to the influence of noise when the damage warning is carried out by comparing the mutation of the intrinsic mode function waveform before and after the structural damage. The operability is strong, the processing precision is improved, and the early warning accuracy is improved. the

附图说明 Description of drawings

图1为本发明所述的结构损伤预警方法的流程图。 Fig. 1 is a flow chart of the structural damage early warning method of the present invention. the

具体实施方式 Detailed ways

本发明的具体实施方式如下： The specific embodiment of the present invention is as follows:

式中，A_i（ω），A_j（ω）分别为a，b点响应信号的傅里叶变换； In the formula, A _{i (ω)} and A _{j (ω)} are the Fourier transform of the response signals at points a and b respectively;

Claims

1. the structural damage method for early warning based on empirical mode decomposition, is characterized in that comprising the steps:

Step 1: obtain the acceleration responsive signal of structural damage front and rear part measuring point, calculate vibration transmissibility function by Fourier transform:

T_{ij (ω)} = \frac{A_{i (ω)}}{A_{j (ω)}} - - - (1)

In formula, A _i(ω), A _j(ω)fourier transform for response signal;

Step 2: using step: the amplitude of the vibration transmissibility function of 1 gained, as analytic signal, obtains by Empirical mode decomposition:

| T_{ij} | = Σ_{k = 1}^{n} a_{k} + r_{n} (t) - - - (2)

In formula, a _kfor the intrinsic mode function of vibration transmissibility function amplitude, r _n(t) be surplus;

Step 3: the definition of the waveform index in contrast signal waveform processing technology, definition intrinsic mode function a _kwaveform index F _kfor:

F_{k} = \sqrt{\frac{1}{N} Σ_{l = 1}^{N} {(a_{k (ω_{l})})}^{2}} / \frac{1}{N} Σ_{l = 1}^{N} | a_{k (ω_{l})} | - - - (3)

In formula, what N was intrinsic mode function counts;

Step 4: intrinsic mode function a before and after computation structure damage _kwaveform index F _kvariation delta F _k, definition damage alarming index is as follows:

DI = \frac{1}{M} Σ_{k = 1}^{M} Δ F_{k} - - - (4)

In formula, M is the quantity of selected intrinsic mode function;

By statistical study, define its threshold value ε, when damage alarming index DI≤ε, structure is intact, and when damage alarming index DI > ε, structure is damaged, sends damage alarming.