S.Mohanty¹, A. Chattopadhyay², J. Wei³, P. Peralta⁴

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 227-250, 2009, DOI:10.3970/sdhm.2009.005.227

Abstract This paper proposes unsupervised system identification based methods to estimate time-series fatigue damage states in real-time. Ultrasound broadband input is used for active damage interrogation. Novel damage index estimation techniques based on dual sensor signals are proposed. The dual sensor configuration is used to remove electrical noise, as well as to improve spatial resolution in damage state estimation. The scalar damage index at any particular damage condition is evaluated using nonparametric system identification techniques, which includes an empirical transfer function estimation approach and a correlation analysis approach. In addition, the effectiveness of two sensor configurations (configuration 1: sensors placed near… More >

S.Mohanty¹, A. Chattopadhyay², J. Wei³, P. Peralta⁴

Structural Durability & Health Monitoring, Vol.5, No.1, pp. 33-56, 2009, DOI:10.3970/sdhm.2009.005.033

Abstract The current state of the art in the area of real time structural health monitoring techniques offers adaptive damage state prediction and residual useful life assessment. The present paper discusses the use of an integrated prognosis model, which combines an on-line state estimation model with an off-line predictive model to adaptively estimate the residual useful life of an Al-6061 cruciform specimen under biaxial loading. The overall fatigue process is assumed to be a slow time scale process compared to the time scale at which, the sensor signals were acquired for on-line state estimation. The on-line state estimation model was based… More >

Chen Zhang¹, Jieren Cheng^1,2,3,*, Xiangyan Tang¹, Victor S. Sheng⁴, Zhe Dong¹, Junqi Li¹

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 657-675, 2019, DOI:10.32604/cmc.2019.06207

Abstract Distributed denial of service (DDoS) attacks launch more and more frequently and are more destructive. Feature representation as an important part of DDoS defense technology directly affects the efficiency of defense. Most DDoS feature extraction methods cannot fully utilize the information of the original data, resulting in the extracted features losing useful features. In this paper, a DDoS feature representation method based on deep belief network (DBN) is proposed. We quantify the original data by the size of the network flows, the distribution of IP addresses and ports, and the diversity of packet sizes of different protocols and train the… More >

Zhongbin Zhou, Pengwan Chen, Fenglei Huang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 125-126, 2011, DOI:10.3970/icces.2011.017.125

Abstract The macroscopic deformation and fracture behavior of a polymer bonded explosive (PBX) simulation material were studied by using Digital Image Correlation (DIC) method. The Brazilian test, semi-circular bending test, punch loading and uniaxial loading experiments were chosen for the study. The whole displacement and strain fields were obtained by using DIC method at macro-scale. New sights into fracture processes and failure mechanisms of simulant samples under different quasi-static loading conditions have been obtained. Macro studies show that the experimental results are in agreement with the theoretical analysis. The experimental methods combined with DIC technique have broad applicability to deformation and… More >

Zhao Zilong, Ma Shaopeng, Wang Xian

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 113-114, 2011, DOI:10.3970/icces.2011.017.113

Abstract As one of the most important photomechanics experimental methods, digital image correlation (DIC) has been widely used in various areas for displacement and deformation field measurement. The main idea of DIC is to resolve the displacement of speckle patterns by independently matching the corresponding patterns on reference and deformed speckle images. In order to add the continuity between the matching of the adjacent patterns, the mesh based DIC (abbreviated mesh-DIC hereafter), in which the whole image are matched, is proposed by Sun, et al. In mesh-DIC, the whole displacement field is characterized by a mesh which is constructed by 4-node… More >

Zeng Xiangfu, Ma Shaopeng, Ma Qinwei, Chen Pengwan

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 111-112, 2011, DOI:10.3970/icces.2011.017.111

Abstract In order to measure the attitude parameters of the projectile, a high-speed 3-dimensional digital image correlation (H3D-DIC) system is designed and constructed. In the H3D-DIC system, two high-speed cameras are used to capture the images of the projectile from two different directions and the 3-dimensional coordinates of the markers painted on projectile are obtained by processing the images using stereovision techniques. Because of the difference on the resolution of the two cameras, the images captured are with different magnification. Therefore, a new correlation program, in which the parameter of pixel size is also included in the correlation schedule, is designed… More >

Xue Feng^*, Xiang Wang, Guobing Zhang, Huimin Xie, Helong Yu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.4, pp. 115-116, 2011, DOI:10.3970/icces.2011.020.115

Abstract Most ceramic materials, because of their inherent brittleness, are susceptible to catastrophic failure under conditions of thermal shock. A novel method for measuring the dynamical deformation is proposed by using of high speed digital image correlation in high temperature environment. The nature texture of ceramic materials can be used as speckle while filters and monochrome produced by LED are applied to suppress black-body radiation and enhance the luminous intensity.

The light from the heated material can alter the Grayscale of material surface and the recognition for material surface will become more and more difficult with the temperature increase. In… More >

Zhenxing Hu, Huimin Xie, Jian Lu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.2, pp. 57-59, 2011, DOI:10.3970/icces.2011.020.057

Abstract Residual stress plays an important role in structural and material manufacturing. Measurement techniques of residual stress can be neatly divided into destructive and non-destructive ones. The destructive techniques are dependent on inferring the original stress from the displacement incurred by completely or partially relieving the stress by removing material. The hole drilling method for residual stress measurement is a destructive method and was first introduced in the 1930s by Mathar. In recent years, the hole drilling method for evaluating residual deformation has been implemented with optical method such as holographic interferometry, electronic speckle pattern interferometry, digital image correlation (DIC), and… More >

L. J. Qin¹, X.F. Li¹, X.G. Yang², Z.W. Zhang², Z. H. Feng², H. Miao¹, Y. Wang¹, L.H. He¹, X.L. Gong^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.1, pp. 3-4, 2011, DOI:10.3970/icces.2011.018.003

Abstract Three-dimensional (3D) woven carbon/carbon (C/C) composites have attracted considerable attention in recent years. In comparison to the laminated composites, the carbon composites show better merit due to their strong through-the-thickness properties, high damage tolerance, and dimensional stability. However, the deformation of these materials is usually non-uniform. The strain field distribution is highly dependent on the heterogeneity of 3D woven structure. Therefore, the traditional techniques such as strain gauge are not suitable for measuring the deformation.

In this presentation, a full-field digital image correlation (DIC) technique was developed. The Iosipescu shear test (v-notched beam test) was employed to load the… More >

Youshi Hong, Chengqi Sun, Aiguo Zhao

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.016.091

Abstract The researches on the behavior of very-high-cycle fatigue (VHCF) for high strength steels have become a new branch in the field of metal fatigue since 1980s. The characteristics of crack initiation and propagation for high strength steels in VHCF regime differ from those in low cycle and high cycle fatigue regimes. One of the most distinct phenomena for VHCF regime is the interior or subsurface crack initiation at inclusions or at other inhomogeneities. In fact, the period of crack initiation and early growth dominates the fatigue life, which is extremely evident for the fatigue process containing VHCF regime. This paper… More >