Abstract

Damage diagnosis has become a valuable tool for asset management, enhanced by advances in sensor technologies that allows for system monitoring and providing massive amount of data for use in health state diagnosis. However, when dealing with massive data, manual feature extraction is not always a suitable approach as it is labor intensive requiring the intervention of domain experts with knowledge about the relevant variables that govern the system and their impact on its degradation process. To address these challenges, convolutional neural networks (CNNs) have been recently proposed to automatically extract features that best represent a system’s degradation behavior and are a promising and powerful technique for supervised learning with recent studies having shown their advantages for feature identification, extraction, and damage quantification in machine health assessment. Here, we propose a novel deep CNN-based approach for structural damage location and quantification, which operates on images generated from the structure’s transmissibility functions to exploit the CNNs’ image processing capabilities and to automatically extract and select relevant features to the structure’s degradation process. These feature maps are fed into a multilayer perceptron to achieve damage localization and quantification. The approach is validated and exemplified by means of two case studies involving a mass-spring system and a structural beam where training data are generated from finite element models that have been calibrated on experimental data. For each case study, the models are also validated using experimental data, where results indicate that the proposed approach delivers satisfactory performance and thus being an appropriate tool for damage diagnosis.

Highlights

  • Recent advances in sensors’ technology and costs reduction have made them a valuable asset for engineers to monitor structures and equipment

  • When analyzing the experimental scenarios with model 3, we can see in Figures 21(c) and 22(c) how similar the results are when compared with models 1 and 2 for experimental beams with one saw cut, which is another indication of the proposed convolutional neural networks (CNNs)-based approach’s robustness at detecting one damaged element

  • Both the MLP and CNN models fail to detect the three damaged elements when trained to detect only one element (i.e., CNN and MLP models 1), the MLP predicts most of the damage level under 30% which, as it was discussed in Section 8.1, is not a reliable diagnosis performance based on the damage missing error (DME) and false alarm error (FAE) values shown in Table 8 and Figure 27

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Summary

Introduction

Recent advances in sensors’ technology and costs reduction have made them a valuable asset for engineers to monitor structures and equipment. Meruane [18] trained an online sequential extreme learning machine (OS-ELM) algorithm to detect, locate, and quantify structural damage using antiresonant frequencies extracted from transmissibility measurements. E input data is a matrix containing the raw time response measured at different locations, and the output is a global classification of the structure in different damage levels (no damage, minor, moderate, and extensive). Erefore, it requires a deep investigation of each application case Another approach is to extract features such as the antiresonant frequencies and use them to detect, locate, and quantify damage. We propose a novel deep CNN-based approach for the detection, localization, and quantification of structural damage that operates on raw transmissibility functions. Erefore, the input to the proposed algorithm are the full transmissibility functions, and it is not necessary to select spectral lines or to extract antiresonant frequencies. A comparison of the CNN-based approach performance with a shallow multilayer perceptron model is discussed in Section 9, and Section 10 presents some concluding remarks

Deep Learning and Convolutional Neural Networks’ Background
Transmissibility Functions
Datasets and Training
Performance Metrics
Case Study 1
Case Study 2
Comparison with Other Models
10. Concluding Remarks
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