M. Lavella¹, T. Berruti¹

Structural Durability & Health Monitoring, Vol.5, No.4, pp. 337-350, 2009, DOI:10.3970/sdhm.2009.005.337

Abstract Results of residual stress measurements on Inconel 718 turbine components after machining are here presented. The work is focused on the experimental detection of the residual stress state produced after turning (orthogonal cutting and standard) and milling. The aim of the experimental activity was to supply an experimental data base of proved reliability for milling and turning model validation. This activity was performed inside the EU STREP project VERDI. The residual stresses were detected by means of X-ray diffraction technique. The experimental plan of measurements was performed on components worked with different working parameters (cutting More >

Smitha Gopinath¹, J. Rajasankar^1,2, Nagesh R. Iyer¹, T. S. Krishnamoorthy¹, B.H.Bharatkumar¹, N. Lakshmanan¹

Structural Durability & Health Monitoring, Vol.5, No.4, pp. 311-336, 2009, DOI:10.3970/sdhm.2009.005.311

Abstract In this paper, a two-phase strain-based constitutive model is proposed for concrete under tension. First phase deals with modelling uncracked concrete while the behaviour of concrete in cracked condition is modelled in second phase with appropriate theoretical support. A bilinear tension softening curve of concrete defined in crack width-stress space is taken as the basis to propose the model. Smeared representation of reinforcement and cracks along with multi-layered geometry definition of reinforced concrete (RC) structures is used to implement the model. Through this, it is shown that change in the orientation of tensile cracks with… More >

Ramana M. Pidaparti¹, Ashwin Belle², Ju Wang³

Structural Durability & Health Monitoring, Vol.5, No.4, pp. 295-310, 2009, DOI:10.3970/sdhm.2009.005.295

Abstract This paper presents the development of a portable integrated wireless sensor module with video camera and ultrasound capabilities to monitor and investigate corrosion damage "in" structures. There are many studies in the literature on structural health monitoring with various sensors systems. However, very few of them utilize low power devices with reliable wireless communication capability to support data-intensive sensing which is a critical issue for practical applications. In this study, we developed a wireless sensor module with video camera capabilities and integrated it with a damage analysis module to investigate the damage of a structure. More >

I.S. Yoon¹, E.A.B. Koenders²

Structural Durability & Health Monitoring, Vol.5, No.4, pp. 275-294, 2009, DOI:10.3970/sdhm.2009.005.275

Abstract The critical chloride content for corrosion initiation is a crucial parameter in determining the durability and integrity of reinforced concrete structures, however, the value is still ambiguous. Most studies reporting the critical threshold of the chloride content have involved experimental measurements of the average amount of the total chloride content at an arbitrary time. Although carbonation can significantly impact on critical threshold chloride content, the majority of the researches have not dealt with this issue in combination with carbonation of concrete. Furthermore, many studies have tried to define the critical chloride content within the scope… More >

I. Benedetti¹, A. Milazzo¹, M.H. Aliabadi²

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 251-274, 2009, DOI:10.3970/sdhm.2009.005.251

Abstract In this work a three-dimensional BEM model is used for the analysis of structures with cracks and surface bonded piezoelectric PZT patches used as strain sensors. The cracked structure is modelled by the dual boundary element method, which allows for accurate and reliable crack analysis, while the piezoelectric patch is analyzed by a finite element state-space approach, that embodies both the full electro-mechanical coupling and the suitable sensor's boundary conditions. The model is used to investigate the strain-transfer mechanism from an host elastic structure to the piezoelectric layer, taking into account the effect of the More >

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 More >

A. Rama Chandra Murthy¹, G.S. Palani¹, Nagesh R. Iyer¹

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 201-226, 2009, DOI:10.3970/sdhm.2009.005.201

Abstract This paper presents methodologies for residual strength evaluation of metallic structural components under fatigue loading. Structural components include plate panels of different crack configurations with and without stiffeners. For stiffened panels, stress intensity factor (SIF) has been computed by using parametric equations based on numerically integrated modified virtual crack closure integral (NI-MVCCI) technique. As a part of residual strength evaluation, remaining life has also been predicted by using standard crack growth models. Various methodologies for residual strength evaluation, namely, plastic collapse condition, fracture toughness criterion and remaining life approach have been described. From the studies, More >

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 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… 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, More >