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Search Results: 1 - 10 of 6373 matches for " structural damage "
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Automatic Damage Detection and Monitoring of a Stitch Laminate System Using a Fiber Bragg Grating Strain Sensor  [PDF]
Agus Trilaksono, Naoyuki Watanabe, Atsushi Kondo, Hikaru Hoshi, Yutaka Iwahori
Open Journal of Composite Materials (OJCM) , 2014, DOI: 10.4236/ojcm.2014.41006
Abstract:


There are numerous aspects and questions related to the use of composite materials for primary structures in aircraft where the structural integrity is the most important factor. This is especially true if the main concerns are that the material should have good reliability and durability for the primary structural application. Composite laminates are highly sensitive to out-of-plane failure due to their low inter laminar fracture toughness. An alternate method to increase the damage resistance is through three-dimensional fibrous reinforcement such as through-the-thickness stitching with a single fiber as the thread. Recent studies have shown that the stitching of standard laminates can enhance damage tolerance to levels obtainable with toughened resin systems. However, for next-generation aircraft, material improvement alone is not enough to assure or increase the safety and reliability of the structure. Continuous damage monitoring during operation will become an important issue in aircraft safety. Embed ding fiber Bragg grating (FBG) technology into the composite structure as strain sensors could potentially solve the above problem because

A Study on Health Monitoring of Structural Damages for Two Stories Model by Using Vibration Test  [PDF]
Toshikazu Ikemoto, Reza Amiraslanzadeh, Masakatsu Miyajima
Open Journal of Civil Engineering (OJCE) , 2014, DOI: 10.4236/ojce.2014.44030
Abstract: Many structures in Japan were built after the war at a revival term or rapid economic growth. These structures have been reached a life in recent years and it is economically not affordable to conduct repair and reconstruct these structures only with a possibility of being damaged. This paper presents an approach to detect the structural damages for two degrees of freedom (2DOF) model. In this study, we conducted Microtremor measurement, free vibration test and vibration test. The 2DOF model was demonstrated the feasibility of using the proposed approach to damage detection of structural member.
Structural Damage Localization by Linear Technique of Acoustic Emission  [PDF]
Md. Tawhidul Islam Khan, Nagafuchi Sunichi, Mehedi Hasan
Open Journal of Fluid Dynamics (OJFD) , 2014, DOI: 10.4236/ojfd.2014.45032
Abstract: Linear source location of acoustic emission (AE) technique has been applied in the present paper for finding the source of material damage under fatigue loading. A plate type structure of ductile cast iron has been used to undergo fatigue damage in a servopulsing machine in the experiment. AE sensors were attached to the specimen for getting the time delay of AE signal propagations through the specimen. After receiving the time delay data of AE signals due to the damage initiation in the material for the provided fatigue loads, linear source location algorithm has been applied and the crack positions are identified. Before applying the technique, a series of pencil lead breaks (PLBs) tests have been conducted upon a ductile cast iron plate of same dimension for verifying the applied algorithm. According to the PLBs varification, the failure location of ductile cast iron (pearlite type) due to the fatigue loading has been characterized. In both experiments, the active ability of the proposed technique for source location of structural damage has been identified clearly and successfully.
Analytical Model on Steel Tanks Damaged by Corrosion  [PDF]
Francisco Casanova-del-Angel, Moisés Gaytán-López
World Journal of Mechanics (WJM) , 2015, DOI: 10.4236/wjm.2015.512026
Abstract: The mechanical behavior of steel employed in the hull of a steel tank damaged by corrosion has been analyzed. The tank was used to filter a deep-water well for an 8-year period. Influence of porosity and dissolution of material may be introduced in the main constitutive relation adding a new damage variable C, which describes electrochemical damage. An elastoplastic theoretical model coupled to damage of a member, and other for damage related to thermodynamic energy are developed. This theoretical development has been used to analyze mechanical behavior of steel used in the body of a steel tank damaged by corrosion in water purifier plants, Eastern System, Mexico City, where three of every ten filters show excessive corrosion inside the steel plate filtration tanks. With samples taken from steel of the tank’s hull and reinforcement of false bottom supporting filtering material inside the tank, metallography tests were carried out; localized and generalized types of corrosion were determined, as well as the type of corrosion composites generated due to anticorrosive coating used inside the tank from its manufacturing.
Fragility Curves of Existing RC Buildings Based on Specific Structural Performance Levels  [PDF]
Marco Vona
Open Journal of Civil Engineering (OJCE) , 2014, DOI: 10.4236/ojce.2014.42011
Abstract: In seismic risk mitigation policies, fragility functions of existing buildings play a fundamental role. In this paper, a procedure to develop analytical fragility curves for Moment Resisting Frame Reinforced Concrete buildings is presented. The design of the selected building typologies was performed according to the codes at the time of construction using force-based methods and the state of the practice at the time of construction. A total of 216 building classes were defined, considering different ages, number of storeys, infill panels, plan dimensions, beam stiffness, and concrete strength. The investigated buildings can be considered low-engineered buildings, using no seismic codes or old seismic codes. The seismic capacity of the selected models representing the existing RC buildings has been evaluated through non-linear dynamic simulations. Seismic response has been analyzed, considering various peak and integral intensity measures and various response parameters, such as ductility demands and Interstorey Drift Ratio (IDR). A new relationship among structural performance, damage levels and interstorey drift ratios for each studied type is introduced, which is calibrated using the damage levels described in EMS98. It is important to highlight that in this study, different thresholds of IDR have been associated with different typologies, considering their different ductility member levels after their different structural responses. Fragility Curves (FCs) for the studied structural types are set up, developed and discussed.
Structural damage identification using signal processing method
Mallikarjuna D Reddy and Seetharaman Swarnamani
International Journal of Advanced Structural Engineering , 2013, DOI: 10.1186/2008-6695-5-6
Abstract: The objective of the current work is to show the effectiveness of using wavelet transform for detection and localization of small damages. The spatial data used here are the rotational mode shapes of the damaged and undamaged plate-like structures. The continuous wavelet transform using complex Gaussian wavelet is used to get the spatially distributed wavelet coefficients so as to identify the damage position on a square plate. The rotational mode shape data of the square plate with damage of different sizes are obtained using ANSYS 9.0. Damage identification for different boundary conditions is studied.
Principais normas e recomenda??es existentes para o controle de vibra??es provocadas pelo uso de explosivos em áreas urbanas: parte II
Bacci, Denise de La Corte;Landim, Paulo Milton Barbosa;Eston, Sérgio Médici de;Iramina, Wilson Siguemasa;
Rem: Revista Escola de Minas , 2003, DOI: 10.1590/S0370-44672003000200012
Abstract: blasting requires control measures related to structural damage to buildings and environmental impacts like ground vibrations, noise, flyrock and air blast. the use of explosives is controlled by federal and state regulations, which involve measurement of parameters to evaluate probable damage in buildings and other type of constructions. in urban areas, the peak particle velocity (ppv) associated with ground vibration and expressed in mm/second, is the best parameter to evaluate possible structural damages. worldwide legal limits vary from a low 2 mm/s for historical buildings to a high 150 mm/s for reinforced concrete. most of the regulations consider peak particle velocity and frequency as a double damage parameter. some regulations were elaborated with an experimental database, involving different types of construction and building materials. others were proposed using empirical data. both regulations present conservative values. the brazilian norm does not consider the frequency and the different types of buildings in the damage evaluation. this paper presents a review of american and other regulations for blasting activities as compared to european regulations.
Principais normas e recomenda??es existentes para o controle de vibra??es provocadas pelo uso de explosivos em áreas urbanas: parte I
Bacci, Denise de La Corte;Landim, Paulo Milton Barbosa;Eston, Sérgio Médici de;Iramina, Wilson Siguemasa;
Rem: Revista Escola de Minas , 2003, DOI: 10.1590/S0370-44672003000100010
Abstract: blasting requires control measures related to structural damage to buildings and environmental impacts like ground vibrations, noise, flyrock and air blast. the use of explosives is controlled by federal and state regulations, which involve measurement of parameters to evaluate probable damage in buildings and other type of constructions. in urban areas, the peak particle velocity (ppv) associated with ground vibration and expressed in mm/second, is the best parameter to evaluate possible structural damages. worldwide legal limits vary from a low 2 mm/s for historical buildings to a high 150 mm/s for reinforced concrete. most of the regulations consider peak particle velocity and frequency as a double damage parameter. some regulations were elaborated with an experimental database, involving different types of construction and building materials. others were proposed using empirical data. both regulations present conservative values. this paper presents a review of the most important european regulations for blasting activities, presenting the state of the art in this area. a second part of paper will show american regulations and the norms of other continents.
Sensitivity of PZT Impedance Sensors for Damage Detection of Concrete Structures
Yaowen Yang,Yuhang Hu,Yong Lu
Sensors , 2008, DOI: 10.3390/s8010327
Abstract: Piezoelectric ceramic Lead Zirconate Titanate (PZT) based electro-mechanicalimpedance (EMI) technique for structural health monitoring (SHM) has been successfullyapplied to various engineering systems. However, fundamental research work on thesensitivity of the PZT impedance sensors for damage detection is still in need. In thetraditional EMI method, the PZT electro-mechanical (EM) admittance (inverse of theimpedance) is used as damage indicator, which is difficult to specify the effect of damage onstructural properties. This paper uses the structural mechanical impedance (SMI) extractedfrom the PZT EM admittance signature as the damage indicator. A comparison study on thesensitivity of the EM admittance and the structural mechanical impedance to the damages ina concrete structure is conducted. Results show that the SMI is more sensitive to the damagethan the EM admittance thus a better indicator for damage detection. Furthermore, this paperproposes a dynamic system consisting of a number of single-degree-of-freedom elementswith mass, spring and damper components to model the SMI. A genetic algorithm isemployed to search for the optimal value of the unknown parameters in the dynamic system.An experiment is carried out on a two-storey concrete frame subjected to base vibrations thatsimulate earthquake. A number of PZT sensors are regularly arrayed and bonded to the framestructure to acquire PZT EM admittance signatures. The relationship between the damageindex and the distance of the PZT sensor from the damage is studied. Consequently, thesensitivity of the PZT sensors is discussed and their sensing region in concrete is derived.
Partial epilepsies: a brief overview
Cendes, Fernando;
Journal of Epilepsy and Clinical Neurophysiology , 2006, DOI: 10.1590/S1676-26492006000200002
Abstract: introduction: the epilepsies represent a heterogeneous group of disorders with diverse etiologic, electrographical and behavioral seizure patterns. objectives: to review recent concepts about epileptogenesis and seizure-induced damage in partial epilepsies. methods: critical review and discussion of some of the relevant papers in this topic. results: mechanisms that are responsible for, or influence, the development of an epileptic condition, as well as its progression, are quite complex, and data on literature are sometimes apparently contradictory. conclusion: this brief overview serves as an introductory remark to the review papers in this supplement.
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