Kyousuke Yamaguchi¹, Nao-Aki Noda², Ker-Kong Chen³, Kiyoshi Tajima³, Seiji Harada¹, Xin Lan¹

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 191-200, 2009, DOI:10.3970/sdhm.2009.005.191

Abstract Wedge-shaped defects are frequently observed on the cervical region of the human tooth. Previously, most studies explained that improper tooth-brushing causes such defects. However, recent clinical observation suggested that the repeated stress due to occlusal force may induce the formation of these wedge-shaped defects. In this study, a two-dimensional human tooth model after a wedge-shaped defect is restored with the composite resin is analyzed by using the finite element method. To obtain the intensity of the singular stress accurately, a method of analysis is discussed for calculating generalized stress intensity factors, which control the singular stress around the corner of… More >

V. Srinivas¹, Saptarshi Sasmal¹, K. Ramanjaneyulu²

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 133-160, 2009, DOI:10.3970/sdhm.2009.005.133

Abstract Many advances have taken place in the area of structural damage detection and localization using several approaches. Availability of cost-effective computing memory and speed, improvement in sensor technology including remotely monitored sensors, advancements in the finite element method, adaptation of modal testing and development of non-linear system identification methods bring out immense technical advancements that have contributed to the advancement of modal-based damage detection methods. Advances in modal-based damage detection methods over the last 20-30 years have produced new techniques for examining vibration data for identification of structural damage. In this paper, studies carried out on damage identification methods using… More >

S. Abdullah¹, S. M. Beden, A. K. Ariffin, N. A. Al-Asady

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 109-132, 2009, DOI:10.3970/sdhm.2009.005.109

Abstract This paper presents a study on fatigue crack growth modelling of thin walled tube aluminium alloy with circumferential crack under constant and variable amplitude loadings. Three fatigue crack growth models were investigated for this purpose, i.e. Walker, Forman and NASGRO. The results showed the differences in the fatigue crack growth simulation under both loading types, although, they have the same stress ratio for the maximum value. Subsequently, it was found that, different models gave different fatigue crack growth behaviour. In another case, many factors were identified towards the fatigue crack growth affection in structures. Hence, an initial crack length and… More >

N.H.M. Kamrujjaman Serker¹, Zhishen Wu

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 87-108, 2009, DOI:10.3970/sdhm.2009.005.087

Abstract This paper presents the study on the temperature sensitivity of some vibration-based damage identification techniques. With the help of a simple supported beam with different damage levels, reliability of these techniques for damage identification in a changing environmental temperature condition was investigated. The temperature effect was considered as the change in modulus of elasticity of the material. The techniques evaluated herein are based on measured modal parameters which use only few mode shapes and/or modal frequencies of the structure that can easily be obtained by dynamic tests. The effect of temperature on identification of different level of damages at different… More >

Ivo Černý¹, Václav Linhart²

Structural Durability & Health Monitoring, Vol.5, No.1, pp. 73-86, 2009, DOI:10.3970/sdhm.2009.005.073

Abstract The experimental programme described in the paper was aimed at an evaluation of fatigue crack growth (FCG) rate and threshold conditions in a reactor pressure vessel steel in laboratory air and in simple aqueous environment. Though the main target of the work was to enlarge the data basis for possible future needs of defect and risk assessment, an emphasis was put on an evaluation of crack growth mechanisms. It was shown that despite some recent works infirming crack closure phenomenon itself or methods of its evaluation, crack closure explained near-threshold fatigue crack behaviour in the specific case of the reactor… More >

J. Toribio¹, J.C. Matos², B. González¹, J. Escuadra²

Structural Durability & Health Monitoring, Vol.5, No.1, pp. 57-72, 2009, DOI:10.3970/sdhm.2009.005.057

Abstract In this paper an automatic (analytical-numerical) procedure is proposed to model the front of a transverse surface crack located in the circular section of a lineal structural element (wire, cable, strand, rod, shaft,..., i.e., a cylindrical geometry) by means of a fitting ellipse, obtaining the ellipse parameters from a series of points in therealcrack front and adjusting them to thetheoreticalfitting ellipse by a least square method. For symmetric cracks two modelling procedures are formulated: (i) in the first one, a fitting ellipse is used wit its centre belonging to the periphery of the circular section of the cylinder; (ii) in… 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 >

G. Giridhara¹, S. Gopalakrishnan²

Structural Durability & Health Monitoring, Vol.5, No.1, pp. 1-32, 2009, DOI:10.3970/sdhm.2009.005.001

Abstract In this paper, a new damage measure in the frequency domain (FDI), which uses the definition of strain energy in the frequency domain, is proposed. The proposed damage index is derived using the definition of frequency domain strain energy. The base line responses and the strain energies are computed using Wavelet Spectral Finite elements, while the strain energies for the damaged structure is computed using four high fidelity experimental responses. The sensitivity of the damage measure in locating cracks of different sizes and orientation is demonstrated on a square plate, the rectangular plate and on a compressor blade. More >

A.B. Mahmud Hasan^1,2, M A Wahab¹, S.M. Guo¹

Structural Durability & Health Monitoring, Vol.4, No.4, pp. 231-240, 2008, DOI:10.3970/sdhm.2008.004.231

Abstract This paper presents details analysis of Heat Affected Zone (HAZ) in High Temperature Vacuum Tube Furnace (HTVTF) to predict fracture region in tube wall due to thermal stress from temperature variation across its thickness. A simple mathematical model is used to illustrate stress concentration arising due to thermal stresses in tube wall and HAZs. Finite element model and analysis were carried out utilizing finite element analysis commercial codes. Combination of thermal stress due to temperature difference determine fracture region. Experimental and simulation results of inside temperature of tube are observed and similar relation have been found. Observation of heat affected… More >

A. Rama Ch,ra Murthy¹, G.S. Palani¹, Nagesh R. Iyer¹

Structural Durability & Health Monitoring, Vol.4, No.4, pp. 221-230, 2008, DOI:10.3970/sdhm.2008.004.221

Abstract Empirical formulae based on experimental data to evaluate concrete penetration depth under impact loading are often used due to the complexity of the phenomena. Several design codes employ empirical formulae for the design of protective barriers. This paper presents the details of relative assessment of the use of well known empirical formulae for evaluation of concrete penetration depth under impact loading. The empirical formulae employed in the present studies include Conwep, Army corps, Haldar, Ammann and Whitney, UKAEA, BRL, Modified Petry and modified NDRC. Appropriate expressions and limitations for these empirical formulae have been provided. Performance of these empirical formulae… More >