Use of Frequency Response for Damage Detection: An Optimization Approach

2016 ◽  
Author(s):  
Hussain Altammar ◽  
Sudhir Kaul ◽  
Anoop Dhingra
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Random Noise ◽  
Crack Size ◽  
Detection Algorithm ◽  
Optimization Approach ◽  
Crack Location ◽  
Linear Elastic ◽  
The Status ◽  
High Level

This paper presents results from a study that investigates the use of frequency response for damage detection. A two-stage optimization approach is proposed to identify the presence of damage in a structure, and to find the location and severity of damage. The proposed approach requires the measured frequency response to statistically quantify the presence and severity of damage. Multiple simulations are presented to demonstrate the capability of the proposed approach. For the simulations, damage is characterized as a local flexibility through the use of a model that is based on Linear Elastic Fracture Mechanics (LEFM). A simply supported beam is used to evaluate the effectiveness of the proposed damage detection algorithm by using the frequency response from the simulation model and incorporating different levels of noise. The optimization approach is found to be successful in determining the status of the beam, and in predicting the crack size and the crack location even in the presence of a high level of noise and with relative coarse sampling of the frequency response. It is also observed that the crack size predicted by the damage detection algorithm is relatively more sensitive to the random noise added to the frequency response as compared to the location of the crack.

scholarly journals Adaptive Probabilistic Optimization Approach for Vibration-Based Structural Health Monitoring

Signals ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 475-489
Author(s):  
Hussain Altammar ◽  
Sudhir Kaul
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Crack Depth ◽  
Optimization Approach ◽  
Probabilistic Algorithm ◽  
False Negatives ◽  
Detection Techniques ◽  
Crack Location ◽  
Damage Location ◽  
Open Edge

This paper presents a novel adaptive probabilistic algorithm to identify damage characteristics by integrating the use of the frequency response function with an optimization approach. The proposed algorithm evaluates the probability of damage existence and determines salient details such as damage location and damage severity in a probabilistic manner. A multistage sequence is used to determine the probability of damage parameters including crack depth and crack location while minimizing uncertainties. A simply supported beam with an open edge crack was used to demonstrate the application of the algorithm for damage detection. The robustness of the algorithm was tested by incorporating varying levels of noise into the frequency response. All simulation results show successful detection of damage with a relatively high probability even in the presence of noise. Results indicate that the probabilistic algorithm could have significant advantages over conventional deterministic methods since it has the ability to avoid yielding false negatives that are quite common among deterministic damage detection techniques.

Numerical and Experimental Study on the Application of Mode Shape Curvature for Damage Detection in Plate-Like Structures

2015 ◽  
Vol 220-221 ◽  
pp. 264-270 ◽  
Author(s):  
Sandris Rucevskis ◽  
Pavel Akishin ◽  
Andris Chate
Keyword(s):  
Experimental Study ◽  
Damage Detection ◽  
Mode Shape ◽  
Research Effort ◽  
Random Noise ◽  
Damage Index ◽  
Simulated Data ◽  
Detection Algorithm ◽  
Mode Shapes ◽  
Laser Vibrometer

The paper describes on-going research effort at detecting and localizing damage in plate-like structures using mode shape curvature based damage detection algorithm. The proposed damage index uses data on exclusively mode shape curvature from the damaged structure. This method was originally developed for beam-like structures. The article generalizes the method of plate-like structures characterized by two-dimensional mode shape curvature. To examine limitations of the method, several sets of simulated data are applied and the obtained results of the numerical detection of damage are validated by comparing them with the findings of the case of the experimental test. The simulated test cases include the damage of various levels of severity. In order to ascertain the sensitivity of the proposed method for noisy experimental data, numerical mode shapes are corrupted with different levels of random noise. Modal frequencies and corresponding mode shapes of an aluminium plate containing mill-cut damage are obtained via finite element models for numerical simulations and by using a scanning laser vibrometer (SLV) for the experimental study.

Use of Wavelets for Mixed-Mode Damage Diagnostics in Warren Truss Structures

2014 ◽  
Author(s):  
Hussain Altammar ◽  
Anoop Dhingra ◽  
Sudhir Kaul
Keyword(s):  
Damage Detection ◽  
Mixed Mode ◽  
Element Model ◽  
Detection Algorithm ◽  
Truss Structures ◽  
Macroscopic Model ◽  
Crack Location ◽  
Multiple Parameters ◽  
Natural Modes ◽  
Damage Diagnostics

The use of the wavelet transform has been gaining widespread acceptance over the last decade as a valuable tool for damage detection. This paper investigates the use of wavelets for detecting mixed-mode, also known as combined mode, cracks in truss structures. The propagation of an open, mixed-mode crack is simulated by using a macroscopic model of damage that is combined with a finite element model of the Warren truss. The natural modes of the truss with varying levels of damage are then used to determine crack location on a specific member of the truss. A damage detection algorithm is developed and the influence of multiple parameters such as truss geometry, crack geometry, number of truss members, etc. is investigated. A direct correlation between damage severity and the magnitude of wavelet coefficients is found for a predefined damage location. It is observed that the proposed damage detection algorithm can be used to successfully detect mixed-mode cracks even in the presence of noise, and even when a relatively coarse sampling of natural modes is used. Multiple simulations are presented and some shortcomings of the proposed algorithm are also discussed in detail.

Study of plate vibrating in fluids having part-through crack at random angles and locations

2021 ◽  
pp. 095440622110127
Author(s):  
Ruqia Ikram ◽  
Asif Israr
Keyword(s):  
Frequency Response ◽  
Multiple Scales ◽  
Peak Amplitude ◽  
Nonlinear Frequency ◽  
Response Curves ◽  
Crack Location ◽  
Cracked Plate ◽  
Nonlinear Frequency Response ◽  
Angle Crack ◽  
Crack Angle

This study presents the vibration characteristics of plate with part-through crack at random angles and locations in fluid. An experimental setup was designed and a series of tests were performed for plates submerged in fluid having cracks at selected angles and locations. However, it was not possible to study these characteristics for all possible crack angles and crack locations throughout the plate dimensions at any fluid level. Therefore, an analytical study is also carried out for plate having horizontal cracks submerged in fluid by adding the influence of crack angle and crack location. The effect of crack angle is incorporated into plate equation by adding bending and twisting moments, and in-plane forces that are applied due to antisymmetric loading, while the influence of crack location is also added in terms of compliance coefficients. Galerkin’s method is applied to get time dependent modal coordinate system. The method of multiple scales is used to find the frequency response and peak amplitude of submerged cracked plate. The analytical model is validated from literature for the horizontally cracked plate submerged in fluid as according to the best of the authors’ knowledge, literature lacks in results for plate with crack at random angle and location in the presence of fluid following validation with experimental results. The combined effect of crack angle, crack location and fluid on the natural frequencies and peak amplitude are investigated in detail. Phenomenon of bending hardening or softening is also observed for different boundary conditions using nonlinear frequency response curves.

Deep AI Enabled Ubiquitous Wireless Sensing

2021 ◽  
Vol 54 (2) ◽  
pp. 1-35
Author(s):  
Chenning Li ◽  
Zhichao Cao ◽  
Yunhao Liu
Keyword(s):  
Great Success ◽  
Wireless Sensing ◽  
Ubiquitous Sensing ◽  
Sensing Systems ◽  
The Status ◽  
Sensing Model ◽  
High Level ◽  
Traditional Approaches ◽  
The Internet Of Things ◽  
High Level Feature

With the development of the Internet of Things (IoT), many kinds of wireless signals (e.g., Wi-Fi, LoRa, RFID) are filling our living and working spaces nowadays. Beyond communication, wireless signals can sense the status of surrounding objects, known as wireless sensing , with their reflection, scattering, and refraction while propagating in space. In the last decade, many sophisticated wireless sensing techniques and systems were widely studied for various applications (e.g., gesture recognition, localization, and object imaging). Recently, deep Artificial Intelligence (AI), also known as Deep Learning (DL), has shown great success in computer vision. And some works have initially proved that deep AI can benefit wireless sensing as well, leading to a brand-new step toward ubiquitous sensing. In this survey, we focus on the evolution of wireless sensing enhanced by deep AI techniques. We first present a general workflow of Wireless Sensing Systems (WSSs) which consists of signal pre-processing, high-level feature, and sensing model formulation. For each module, existing deep AI-based techniques are summarized, further compared with traditional approaches. Then, we provide a view of issues and challenges induced by combining deep AI and wireless sensing together. Finally, we discuss the future trends of deep AI to enable ubiquitous wireless sensing.

Investigation of Sensor Placement in Lamb Wave-Based SHM Method

2012 ◽  
Vol 518 ◽  
pp. 174-183 ◽  
Author(s):  
Pawel Malinowski ◽  
Tomasz Wandowski ◽  
Wiesław M. Ostachowicz
Keyword(s):  
Wave Propagation ◽  
Damage Detection ◽  
Guided Waves ◽  
Sensor Placement ◽  
Detection Algorithm ◽  
Piezoelectric Sensors ◽  
Optimal Placement ◽  
Laser Vibrometer ◽  
Contact Method ◽  
Monitoring Method

In this paper the investigation of a structural health monitoring method for thin-walled parts of structures is presented. The concept is based on the guided elastic wave propagation phenomena. This type of waves can be used in order to obtain information about structure condition and possibly damaged areas. Guided elastic waves can travel in the medium with relatively low attenuation, therefore they enable monitoring of extensive parts of structures. In this way it is possible to detect small defects in their early stage of growth. It is essential because undetected damage can endanger integrity of a structure. In reported investigation piezoelectric transducer was used to excite guided waves in chosen specimens. Dispersion of guided waves results in changes of velocity with the wave frequency, therefore a narrowband signal was used. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at points belonging to a defined mesh. An artificial discontinuity was introduced to the specimen. The goals of the investigation was to detect it and find optimal sensor placement for this task. Determination of the optimal placement of sensors is a very challenging mission. In conducted investigation laser vibrometer was used to facilitate the task. The chosen mesh of measuring points was the basis for the investigation. The purpose was to consider various configuration of piezoelectric sensors. Instead of using vast amount of piezoelectric sensors the earlier mentioned laser vibrometer was used to gather the necessary data from wave propagation. The signals gather by this non-contact method for the considered network were input to the damage detection algorithm. Damage detection algorithm was based on a procedure that seeks in the signals the damage-reflected waves. Knowing the wave velocity in considered material the damage position can be estimated.

Nondestructive Detection of a Crack in a Triangular Cantilever Beam Based on Frequency Measurement

2007 ◽  
Vol 353-358 ◽  
pp. 2285-2288
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao
Keyword(s):  
Cantilever Beam ◽  
Natural Frequencies ◽  
Frequency Measurement ◽  
Crack Size ◽  
Force Sensors ◽  
Rotational Spring ◽  
Cantilever Deflection ◽  
Crack Location ◽  
Small Force ◽  
Point Of Intersection

Triangular cantilevers are usually used as small force sensors in the transverse direction. Analyzing the effect of a crack on transverse vibration of a triangular cantilever will be of value to users and designers of cantilever deflection force sensors. We present a method for prediction of location and size of a crack in a triangular cantilever beam based on measurement of the natural frequencies in this paper. The crack is modeled as a rotational spring. The beam is treated as two triangular beams connected by a rotational spring at the crack location. Formulae for representing the relation between natural frequencies and the crack details are presented. To detect crack details from experiment results, the plots of the crack stiffness versus its location for any three natural modes can be obtained through the relation equation, and the point of intersection of the three curves gives the crack location. The crack size is then calculated using the relation between its stiffness and size. An example to demonstrate the validity and accuracy of the method is presented.

Conspicuous consumption of luxury experiences: an experimental investigation of status perceptions on social media

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Carolin Siepmann ◽  
Lisa Carola Holthoff ◽  
Pascal Kowalczuk
Keyword(s):  
Social Media ◽  
Personal Characteristics ◽  
Conspicuous Consumption ◽  
Individual Characteristics ◽  
Luxury Goods ◽  
Content Type ◽  
The Status ◽  
Self Actualization ◽  
The Individual ◽  
High Level

Purpose As luxury goods are losing their importance for demonstrating status, wealth or power to others, individuals are searching for alternative status symbols. Recently, individuals have increasingly used conspicuous consumption and displays of experiences on social media to obtain affirmation. This study aims to analyze the effects of luxury and nonluxury experiences, as well as traditional luxury goods on status- and nonstatus-related dimensions. Design/methodology/approach After presenting the theoretical foundation, the authors conduct a study with 599 participants to compare status perceptions elicited by the conspicuous consumption of luxury goods, luxury experiences and nonluxury experiences. The authors investigate whether experiences that are visibly consumed on Instagram are replacing traditional luxury goods as the most important status symbols. Furthermore, the authors examine the effects of the content shown on nonstatus-related dimensions and analyze whether status perceptions differ between female and male social media communicators. Finally, the authors analyze how personal characteristics (self-esteem, self-actualization and materialism) influence the status perceptions of others on social media. Findings The results show that luxury goods are still the most important means of displaying status. However, especially for women, luxury experiences are also associated with a high level of social status. Thus, the results imply important gender differences in the perceptions of status- and nonstatus-related dimensions. Furthermore, the findings indicate that, in particular, the individual characteristics of self-actualization and materialism affect status perceptions depending on the posted content. Originality/value While the research has already considered some alternative forms of conspicuous consumption, little attention has been given to experiences as status symbols. However, with their growing importance as substitutes for luxury goods and the rise of social media, the desire to conspicuously consume experiences is increasing. The authors address this gap in the literature by focusing on the conspicuous display of luxury and nonluxury experiences on social media.

scholarly journals Detection method for auto guide vehicle’s walking deviation based on image thinning and Hough transform

2019 ◽  
Vol 52 (3-4) ◽  
pp. 252-261 ◽  
Author(s):  
Xiaohua Cao ◽  
Daofan Liu ◽  
Xiaoyu Ren
Keyword(s):  
Hough Transform ◽  
Detection Method ◽  
Detection Algorithm ◽  
Visual Navigation ◽  
Guide Line ◽  
Actual Environment ◽  
Lane Line ◽  
Image Thinning ◽  
High Level ◽  
Refinement Algorithm

Auto guide vehicle’s position deviation always appears in its walking process. Current edge approaches applied in the visual navigation field are difficult to meet the high-level requirements of complex environment in factories since they are easy to be affected by noise, which results in low measurement accuracy and unsteadiness. In order to avoid the defects of edge detection algorithm, an improved detection method based on image thinning and Hough transform is proposed to solve the problem of auto guide vehicle’s walking deviation. First, the image of lane line is preprocessed with gray processing, threshold segmentation, and mathematical morphology, and then, the refinement algorithm is employed to obtain the skeleton of the lane line, combined with Hough detection and line fitting, the equation of the guide line is generated, and finally, the value of auto guide vehicle’s walking deviation can be calculated. The experimental results show that the methodology we proposed can deal with non-ideal factors of the actual environment such as bright area, path breaks, and clutters on road, and extract the parameters of the guide line effectively, after which the value of auto guide vehicle’s walking deviation is obtained. This method is proved to be feasible for auto guide vehicle in indoor environment for visual navigation.

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