bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Study on the Fire Behavior of Concrete Segments in Tunnel Linings
Authors: Park Kyung Hoon , Kim Heung Youl , Min Byung Youl
Published: August 2011

As soon as the plan to build deep and long tunnels in Korea was announced, guaranteeing fire-resistance of R/C tunnel linings became an important issue. As a matter of fact, the R/C segments used in bored tunnels are structural members which are requested to resist both the transverse pressure of the soil and the longitudinal thrust of the TBM. Because of the temperature sensitivity of the high-performance concrete (compressive strength>40 MPa) that will be used, proper measures should be taken against possible fire-induced damage, like surface spalling and deterioration of the reinforcement. In the past, concrete linings were built in Korea with scanty attention to their fire safety, as demonstrated by the lack of studies on fire resistance of both materials and structures. Therefore, in this study the objective is how to improve the safety of R/C tunnel linings in case of fire, by comparing the damage observed in some full-scale tests recently performance in Korea with the damage observed in the tests performed by EFNARC (European Federation of Producer and Applicators of Specialist Products for Structures) and by investigating the fire behavior of a concrete lining as a whole.
SMA in Mitigation of Extreme Loads in Civil Engineering: Damping Actions in Stayed Cables
Authors: Torra Vicenç , Isalgue Antonio , Auguet Carlota , Carreras Guillem , Lovey Francisco C. , Terriault Patrick , Dieng Lamine
Published: August 2011

Reliable use of Shape Memory Alloys (SMA) in mitigation of extreme load effects requires a deep study of the SMA behavior according to the necessities of the application. Damping the oscillations induced by one storm of three or four days with a strong wind and/or rain usually requires more than one million of working cycles. A SMA damper is checked in to two realistic cables of ELSA and of IFSTTAR. The measurements establish that the SMA damping device reduces drastically the oscillation amplitude. Technical suggestions for the preparation of the dampers built by several SMA wires of NiTi with 2.46 mm of diameter are included. The choice of appropriate length and the choice of the number of required SMA wires are suggested. Moreover, a suitable simulation by proprietary SMA routine inside ANSYS is included.
Strengthening of a Multistory R/C Building under Lateral Loading by Utilizing Ties
Authors: Markogiannaki Olga , Tegos Ioannis
Published: August 2011

The scope of the study is to examine of the possibility of applying steel ties, which can consist of common steel wires, as means to restrain the seismic displacements of buildings structural systems. The method seems to be competitive to the conventional ones, since fewer disturbances are created during the retrofitting works, i.e. the installation of ties as compared to the conventional strengthening methods. The method also proved to be more economic than the conventional method of constructing and infilling concrete walls in the vulnerable structural system. Initially, the efficiency of the ties was studied in multistory building models, such as frame, combined frame-wall and combined frame-wall without beams. Based on the results of the analytical study, the method was applied on a 5 storey existing and seismically deficient building. More specifically, the long side of the building was chosen for the method’s application. The last choice was deemed more preferable due to the fact that it has no openings which allowed the easy application of straight ties. The one end of the ties is anchored in the concrete slab of the upper stories, while the other end on the basement’s upper concrete slab. Although the seismic demand was higher for the implemented solution of the steel wires due to multiple loading, caused by the low value of the seismic performance coefficient equal to 1.5, an adequate level of earthquake resistance was achieved. The results of the case study confirmed the applicability of the proposed method. It should be underlined that the ties method looks promising in the field of structures retrofitting and could be studied analytically in campaigns, either independently or in combination with the conventional in concrete shear wall method.
Experimental Study on Shock Absorption Effect of Mechanical Device Utilizing Wedge and Rubber
Authors: Ishibashi Kazuyoshi , Katsuki Satoshi , Hirose Akinori , Tanaka Kenji
Published: August 2011

This paper presents an experimental study on the impact absorption effect of the device which utilizes both shear deformation ductility of rubbers and a wedge mechanical system. Two types of experiments, i.e., static and impact loading, are carried out. Rate effect on resistance of the device is checked by comparison between static loading test results. The impact absorption effect is discussed by comparisons of the impact loading test between the impact load and the transmitting load. The other some impact absorption effects are discussed on the impact loading test.
The Influence of Concrete Surface Preparation when Fiber Reinforced Polymers with Different Anchoring Devices are Being Applied for Strengthening R/C Structural Members
Authors: Manos G.C. , Katakalos Konstantinos , Kourtides V.
Published: August 2011

The aim of this study is to investigate the influence of concrete surface preparation when either steel or carbon fiber reinforced polymers (FRP) are applied for strengthening applications of R/C members. The present study also investigates the anchorage or not of the applied FRP strips on the volume of concrete. For this purpose special concrete specimens were fabricated and were used to attach CFRP or SRP strips with or without anchoring and with or without contact surface treatment. The experimental results indicate that the concrete surface preparation is important and results in an increase of the load bearing capacity when the FRP strip is not anchored. When an anchoring device is employed, the concrete surface preparation is of no significance. With a properly designed anchoring device, a significant increase in the bearing capacity was observed and the failure was that of the fracture of the FRP strips for all such specimens. The highest FRP material exploitation was achieved in the specimen that utilises the patented anchoring device together with two layers of SRP strips. Debonding of the FRP strips, or failure of the anchoring device, results as was to be expected, in relatively unsatisfactory FRP material exploitation.
Experimental Investigation of High Strain-Rate Behaviour of Glass
Authors: Peroni Marco , Solomos George , Pizzinato Valerio , Larcher Martin
Published: August 2011

The purpose of this work is to assess the dynamic mechanical behaviour of a commercial glass similar to that of the laminated glass structures used for protection and security applications in buildings. In particular, the study has been focussed on the influence of the strain-rate on the compressive (standard compression test) and tensile (splitting tensile test) strength of this glass. Tests at different strain-rates have been performed in the range between 10-3 to 103 s-1 using standard test equipment for quasi-static tests and a SHPB equipped with a high-speed camera for the dynamic ones. Test data for compression tend to show that there is no substantial sensitivity to the strain-rate concerning ultimate strength and Young modulus. An appreciable increase in the ultimate tensile strength is revealed at higher strain-rate.
Development of Negative Stiffness Dampers for Seismic Protection
Authors: Iemura Hirokazu , Toyooka Akihiro , Higuchi Masaki , Kouchiyama Osamu
Published: August 2011

In the first part of this study, theoretical and numerical evaluation of negative stiffness appearing in the skyhook control is conducted. The skyhook control is widely known for the vibration control method in the mechanical engineering field. The skyhook control can also achieve absolute response reduction. In order to realize a negative stiffness, however, the control force that accelerates the deformation should be generated. At present, such a performance is achieved only by using loading actuators or semi-active devices with sophisticated controllers and sensors. In the second part of this research, a new damper realizing a negative stiffness and stable energy dissipation in a passive manner is proposed, and its dynamic performance is investigated through large-scale shaking table tests. It is confirmed that the innovative negative stiffness passive damper reduces both the absolute acceleration and the relative displacement of a bridge model.
Clearing of Blast Waves on Finite-Sized Targets – an Overlooked Approach
Authors: Tyas Andrew , Bennett Terry , Warren James A. , Fay Stephen D. , Rigby Sam E.
Published: August 2011

The total impulse imparted to a target by an impinging blast wave is a key loading parameter for the design of blast-resistant structures and façades. Simple, semi-empirical approaches for the prediction of blast impulse on a structure are well established and are accurate in cases where the lateral dimensions of the structure are sufficiently large. However, if the lateral dimensions of the target are relatively small in comparison to the length of the incoming blast wave, air flow around the edges of the structure will lead to the propagation of rarefaction or clearing waves across the face of the target, resulting in a premature reduction of load and hence, a reduction in the total impulse imparted to the structure. This effect is well-known; semi-empirical models for the prediction of clearing exist, but several recent numerical and experimental studies have cast doubt on their accuracy and physical basis. In fact, this issue was addressed over half a century ago in a little known technical report at the Sandia Laboratory, USA. This paper presents the basis of this overlooked method along with predictions of the clearing effect. These predictions, which are very simple to incorporate in predictions of blast loading, have been carefully validated by the current authors, by experimental testing and numerical modelling. The paper presents a discussion of the limits of the method, concluding that it is accurate for relatively long stand-off blast loading events, and giving some indication of improvements that are necessary if the method is to be applicable to shorter stand-off cases.
Blast Testing and Analysis of Composite Cable Shields
Authors: Smith Zachery I. , Fyfe Edward R. , Wisotzkey Sean P.
Published: August 2011

Suspension and cable-stayed bridge cables are currently vulnerable to multiple scenarios that can jeopardize the integrity of the bridge. These can include accidental truck fires and more recently, terrorist attacks. The inherent nature of suspension and cable-stay bridges leaves little redundancy to their structural loads paths. For this reason they are more susceptible to terrorist attacks than possibly any other structure. This paper looks at a composite cable shield composed of various materials each tailored to protect against unique threats. Several test specimens were manufactured by Fyfe Co. LLC and proof tested by the U.S. Army Corps of Engineers. Multiple threat scenarios were simulated by plastic explosives, extreme heat differentials, and various cutting mechanisms. The distinctive prefabricated connections provide for fast installation and a very robust design to prevent cable shield separation under extreme loads. Through the use of several advanced composite materials the cable shields provide a widespread umbrella of protection for potential threats.
Research of Elastomeric Protective Layers Subjected to Blast Wave
Authors: Malachowski Jerzy , Niezgoda Tadeusz
Published: August 2011

The paper is based on non–linear finite element analysis of the blast wave effects on structures, caused by the detonation of explosive materials. Dynamic response of a structure with and without elastomeric layers subjected to the shock wave produced by the detonation of high explosive materials is presented in this paper. Coupled Euler and Lagrange formulation are used in the finite element analysis of such problems to accurately represent the detonation phenomenon. Research related to blast wave propagation is not only aimed at its effect on structures but also on developing new concepts of protective panels. The research carried out on various structures (such as multi–layer panels) has been performed to find out the most efficient protection against a detonation wave. Tests of multi-layer protective panels ability to absorb the explosion energy were also conducted under field conditions and confirmed in numerical studies. The application of structural protective layers made of elastomeric material significantly reduced the blast wave thanks to dissipation capabilities. Additionally, the shape effect of structural steel elements (streamlined profile) during the interaction process with a shock wave has been also confirmed.
Progressive Collapse Mitigation in Multistory Tilt-up Structural Systems
Authors: Quiel Spencer , Marjanishvili Shalva
Published: August 2011

Low-rise office buildings constitute a large portion of the building inventory that is governed by criteria published by the US government. In recent efforts to save costs, building owners and others in this construction sector have explored the use tilt-up construction for these facilities, which eliminates the perimeter steel framing and integrates the concrete façade into the load bearing structure. According to the criteria, many of these buildings meet the height and occupancy thresholds for which progressive collapse resistant design is required. Two major US government agencies, DoD and GSA, provide methodologies for progressive collapse analysis of common structural systems. However these guidelines include limited guidance for the design of tilt-up construction. This paper outlines a methodology for progressive collapse resistant design of tilt-up structures and discusses the increases in reinforcement needed for a prototype building.
Numerical Simulations of Rockfall Protection Retaining Wall Joined to Steel-Pile Foundation
Authors: Yamaguchi Satoru , Nishi Hiroaki , Kon-No Hisashi , Omote Shin Ya , Kishi Norimitsu , Ushiwatari Yuji
Published: August 2011

In Japan, many rockfall protection walls have been constructed along the nationalhighways in mountainous areas. Up till now, usually these were gravity-type walls. However, ifthere is not much space between the wall and the edge of the cliﬀ, it may not be easy to constructa normal type of wall. To rationally install the wall in these areas, a retaining wall connectedto a steel pile foundation attached to a two-layer absorbing system was recently developed.Here, in order to establish a rational design for this type of retaining wall, an impact responseanalysis was performed by means of three-dimensional elasto-plastic FE analysis. The two-layerabsorbing system used here is composed of a 15 cm thick reinforced concrete slab together with a50 cm thick expanded polystyrene (EPS) block. The retaining wall is connected to the steel pilesby inserting H-section steel members embedded in the wall. The applicability of the proposedFE analysis method was veriﬁed by comparing with the prototype impact test results.
Real Scale Experiments on Rockfall Protection Barriers
Authors: Trad Ayman , Limam Ali , Robit Philippe
Published: August 2011

In the rockfall protection barriers, the role of the net is to diffuse the efforts to the braking devices which absorb the energy and slow down the velocity of the block. An innovative braking device working by the buckling of metallic tubes is developed by quasi-static and dynamic tests. Real scale experiments on the entire structure are done and presented here. These tests are performed as the recommendations of the new Guideline for European Technical Approval concerning the falling rock protection kits, named ETAG 27.
Mitigation of Ground Shock Effects on Buried Structures–Advantages of Unsaturated Ground
Authors: Leong Eng Choon , Anand Sarma , Lim Chee Hiong
Published: August 2011

Going underground has been proven an effective defense strategy. However, defense structures below the ground need to be designed for ground shock loading. In Singapore, two thirds of the land area is covered by residual soils which are mostly unsaturated. But soil moisture condition in a tropical country like Singapore can alternate between dry and wet conditions. This paper summarizes the findings of a series of small-scale field tests to investigate the effects of degree of saturation on ground shock. A new perspective is presented which will help in developing technologies to mitigate ground shock effects on underground structures in future.
Fire Safety Engineering for Open and Closed Car Parks: C.A.S.E. Project for L’Aquila
Authors: Nigro Emidio , Cefarelli Giuseppe , Ferraro Anna , Manfredi Gaetano , Cosenza Edoardo
Published: August 2011

The Fire Safety Engineering (FSE) is a multi-discipline aimed to define the fire safety strategy for buildings under fire conditions, in which structural stability and control of fire spread are achieved by providing active and/or passive fire protection. In this paper, the aspects of FSE for the structural safety checks in case of fire are shown with reference to Italian and European standards. FSE requires the choice of a performance level, the definition of design fire scenarios, the choice of heat flows models and several numerical thermo-mechanical analyses. The information provided by a significant research, performed in Europe for open and closed car parks, are used to apply the FSE to the car parks of the new buildings of the C.A.S.E. Project for L’Aquila, characterized by steel columns supporting the seismically isolated superstructure. The results of the application of the FSE approach are reported and discussed in the second part of the paper.
Robustness Based Structural Design: An Integrated Approach for Multi-Hazard Risk Mitigation
Authors: Dubina Dan , Dinu Florea
Published: August 2011

Multi-story building structures can suffer local damage or even structural collapse in case of extreme natural or man-made hazards. While all buildings are at a certain risk, some attributes can reduce the risk by reducing the vulnerability. One such attribute is the use of structural systems which can ensure that, in case of abnormal loads or failure of some elements, the collapse is prevented and the risk to occupants is reduced. Mitigation of some specific hazard can also help to reduce the risk, eg. protective barriers against impact or stand-off distance against direct effects of blast. Past experience has shown that structures that are designed according to seismic design philosophy can survive to a multiplicity of hazards. The objective of the paper is the adaptation of seismic design methodology to robust design demands of multistory frame buildings prone to multi-hazard scenarios. The hazard is modeled by removal of critical members. Nonlinear dynamic analyses are carried out in order to evaluate their robustness.
Spatial Geotechnical Information-Based Assessment of Seismic Structural Vulnerability Related to Site Effects at Daegu Metropolitan City
Authors: Sun Chang Guk
Published: August 2011

Site effects inducing the amplification of earthquake ground motion are strongly influenced by the local geologic conditions such as soil thickness and stiffness. Most of major cities in the world are located across wide area where there are various surface topographies and corresponding subsurface geotechnical conditions. To prepare earthquake-induced structural damages and corresponding casualties in an urban area, hence, the spatial prediction of geotechnical information in the entire region is not only important but fundamental. In this study, to predict reliably spatial geotechnical information based on restricted number of boring data, a procedural methodology is introduced and applied into GIS tool. Particularly, an inland metropolitan city, Daegu, in Korea, was selected for implementing an integrated GIS-based geotechnical information system. Based on the various data combined over the area of interest, geotechnical layers information was reliably predicted in the entire region of Daegu with three-dimensional feature. For practical application of geotechnical information to assessing the site effects in the target urban area, seismic zoning maps of bedrock depth and site period were created and presented as regional basic information on seismic disasters. Spatial distribution on seismic structural vulnerability potential in the area of interest was intuitively examined from the seismic zoning maps. Furthermore, seismic zonations were also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation of structures in the Daegu area.
Dynamic Monitoring Systems for Structures under Extreme Loads
Authors: Inaudi Daniele , Favez Pascale , Belli Riccardo , Posenato Daniele
Published: August 2011

The dynamic monitoring of civil structures such as buildings and bridges is traditionally approached using acceleration and velocity sensors. When a monitoring program is designed to address concerns related to the level of strain in certain members, fatigue or displacements due to extreme loads, it is sometimes advantageous to measure those parameters directly, instead of deriving them from acceleration or velocity data. Inhomogeneous construction materials such as concrete, stone or masonry require the use of long-gauge sensors to measure strain, since local sensors can provide erroneous data due to local material changes. On the other hand, acceleration and tilt sensors are very useful to capture the global deformations and displacements. The development of long-gauge-length fiber optic sensors can be considered as a useful addition to the toolkit of those interested in the structural dynamics. The system can monitor structures over long periods of time at acquisition frequencies up to 10 kHz and with sub-microstrain resolution. The possibility of obtaining static and dynamic measurements from the same sensor is another advantage of this technology. For acceleration and tilt monitoring, MEMS sensors are now recognized as a powerful and low-cost alternative to more traditional sensor types. Fully-integrated sensors with 3-axis accelerometers and two-axis tiltmeters are now available in a compact packaging that also contain all data acquisition electronics and can be easily deployed in new or existing structures, connecting them directly to an Ethernet network. This contribution briefly introduces fiber optic and MEMS sensing technologies and will than illustrate their application to structural health monitoring through several examples, including the new I35W bridge in Minneapolis USA, the Ile d’Orléans suspension Bridge in Québec Canada and the shaking-table test of a full-scale masonry building reinforced with composite materials.
Structural Individuation of Damages Occurred on St. Gemma Church in Goriano Sicoli during the 2009 L’Aquila Earthquake
Authors: Criber Emanuela , Brando Giuseppe , De Matteis Gianfranco
Published: August 2011

The current paper presents the first part of a study in progress devoted to analyse the St. Gemma church in Goriano Sicoli, which has been seriously damaged by the 2009 L’Aquila earthquake. Firstly, the main effects provoked by L’Aquila Earthquake on ancient historical centres, with particular regard to buildings belonging to the cultural heritage, are described. Then, the St. Gemma church is investigated in detail. The main geometry and structural details of the church are shown and damage occurred during to the seismic event of 6.04.09 is critically analysed and discussed. Finally, the main outcomes of dynamic tests carried out on the damaged church, in order to detect its main natural frequencies and mode shapes, are provided.
Dynamic Behaviour of Reinforcing Steel Bars in Tension
Authors: Cadoni Ezio , Dotta Matteo , Forni Daniele , Tesio Nicoletta
Published: August 2011

In this paper the preliminary results of the tensile behavior of reinforced steel in a large range of strain rates are presented. Tensile testing at several strain rates, using different experimental set-ups, was carried out. For the quasi-static tests a universal electromechanical testing machine with the maximum load-bearing capacity of 50 kN was used, while for the intermediate and high-strain rate regimes a hydro-pneumatic apparatus and a JRC-Split Hopkinson Tensile Bar respectively were used. The target strain rates were set at the following five levels: 10-3, 30, 250, 500, and 1000 1/s. The specimens used in this research were round samples having 3mm in diameter and 5mm of gauge length obtained from reinforcing bars. Finally, the material parameters for Cowper-Symonds and Johnson-Cook models were determined.
Analysis of Impact Response of Sand Cushion for Rockfall by Distinct Element Method
Authors: Watanabe Takashi , Masuya Hiroshi , Satoh Akita , Nakamura Sachio
Published: August 2011

In order to know efficiently the impact behavior of the actual size sand cushion under rock fall, to achieve a lot of impact experiments under various conditions or to analyze those phenomena by use of reliable accurate methods is generally required. However, there is difficulty in many cases to achieve experiments because of financial reason. Therefore, the analysis method to reproduce full-scale impact behavior is indispensable. From this point of view, we have developed Distinct Element Method. The method to model the body to collide like a rock fall by an assembly of many small elements and the method to present a sand cushion as an assembly of many elements which have different size with randomness were shown. The validity of this method was shown by the comparison with experimental results.
Effect of Residual Stresses on Bending Test in Bilayer of SOFC
Authors: Wang Feng Hui , Lou Kang , Wang Yong Jun
Published: August 2011

When to test the failure stress of Solid Oxide Fuel Cell system, bending approach is consider as one of the convenient ways. The failure stresses are calculated by the elasticity multi -layered theory, in which the neutral axis is determined by the mechanical properties of materials and the thickness of the layers. When cooling from the sintered temperature, residual stresses arise in the multi-layered system due to the mismatch of the thermal expansion coefficients, in this case, the thermal elastic theory point out that the neutral axis depends on residual stress. In this paper, the effect of residual stress on the shift of neutral axis and consequently the failure stress of SOFCs presented, the finite element method was also employed to calculate the SOFCs before and after reduction. The results show that the residual stresses has a distribution along the thickness of the layers, the neutral axis also shifts with the residual stress and the external bending moment, when to test and value the bending stress, the shift of neutral axis should be considered.
Formation of ZnO Nanorods via Seeded Growth Hydrothermal Reaction
Authors: Ridhuan Nur Syafinaz , Fong Yeo Pet , Lockman Zainovia , Khairunisak Abdul Razak
Published: August 2011

In this study, ZnO nanorods was formed on a seeded substrates prepared by thermal oxidation of Zn foil followed by hydrothermal reaction. ZnO seed was prepared via thermal oxidation process at 300°C for 10 minutes to form uniform circular nanosize grains that were suitable as a seeded template for the growth of ZnO nanorods via hydrothermal reaction. Several hydrothermal reaction parameters were studied; hydrothermal reaction temperature, ratio of zinc nitrate to hexamethylamine and pH. In hydrothermal reaction, the formation of ZnO nanorods occurs due to thermal degradation of hexamethylamine (HMT) which released hydroxyl ions that react with Zn ions in the precursor solution. Well aligned, ZnO nanorods with length of ~700 nm, base diameter of ~200 nm and top diameter of less than 30 nm needle-like structure were formed on seeded Zn substrate with concentration ratio of zinc nitrate to hexamethylamine 0.1M:0.1M, pH 6-7 at hydrothermal reaction temperature of 80°C
Gait Parameters Determination by 2D Optical Motion Analyzer System
Authors: Mahyuddin Andi Isra , Mihradi Sandro , Dirgantara Tatacipta , Maulido Prisanto N.
Published: August 2011

In the present work, an optical motion-capture system combined with software for 2D clinical gait analysis is utilized to determine spatiotemporal gait parameters such as stride-length, cadence, cycle-time, and speed as well as joint angles. The developed system consists of a video camera with a maximum speed of 90fps, LED markers, PC and technical computing software, which are developed for tracking markers attached to human body during motion and to calculate kinematics and kinetics parameters of human gait. Gait data of 60 subjects within the age group between 18 to 49 years are measured as part of an effort to develop normal walking database of Indonesian people. In the experiments, the subject is instructed to walk in a specially-arranged measurement area, which is calibrated using the Direct Linear Transformation (DLT) method. Before the measurement, the body posture of each subject is evaluated to ensure normalcy. To validate the system, the obtained gait data is compared to the available normal walking database, and the results obtained by the system show good compatibility.
A Quantitative Damage Identification Method for CF/EP Composite Laminates Based on Lamb Waves
Authors: Liu Yu , Li Zheng , Gong Ke Zhuang , Su Xian Yue
Published: August 2011

This paper describes a quantitative damage identification method for CF/EP composite laminates based on Lamb waves excited by distributed PZT wafers. The fundamental symmetric mode S0 is considered to detect defects (hole) in the plate. The Morlet wavelet and the cross-correlation analysis are introduced as signal processing tools for determining the time-of-flight (ToF) of Lamb wave. Considering the difference of Lamb wave velocities in different directions in a composite plate, the relationship of Lamb wave velocity in a unidirectional fibre reinforced laminate is studied and validated experimentally and numerically. In addition, a defect identification approach is revealed based on a regular arrangement of PZT wafers. Then, on the basis of the relationship of the wave velocity and the ToF, the location of a hole is identified by proposed method. Results demonstrate that the method is feasible in quantitative diagnosis of composite structures.
Multi Soliton Generation for Enhance Optical Communication
Authors: Afroozeh Abdolkarim , Amiri Iraj Sadegh , Jalil Muhammad Arif , Kouhnavard Mojgan , Ali Jalil , Yupapin P. Preecha
Published: August 2011

We propose a new optical system that can be used to form the multi-soliton pulses within the micro-ring resonators. The system consists of two micro-ring resonators and an add/drop multiplexer that can be integrated into a single system. The large bandwidth signal is generated by using a soliton pulse propagating in a Kerr-type nonlinear medium. The tuned soliton pulses in either spatial or temporal modes are obtained by using the add/drop multiplexer. Results show the generation of multi-soliton pulses within the micro-ring resonator can be achieved for long distance communication. This results in an increase in the number of channels and spaces with a large free spectrum range (FSR) of 650 pm for dense wavelength division multiplexing (DWDM).
New Biaxial Compression Test Device for Metallic Materials with Reverse-Type Differential Rotary to Linear Conversion Mechanism
Authors: Shimizu Ichiro
Published: August 2011

New rotary to linear conversion mechanism named "reverse-type differential rotary to linear conversion mechanism (RDRLCM)" was invented for simultaneous achievement of large load capacity and precise displacement control, for compression test devices and press forming machines. The new mechanism was developed and incorporated as loading systems into an original biaxial compression test device, and thus, its fundamental performance was investigated. The results revealed that the loading system by the new rotary to linear conversion mechanism were able to generate compression force of about three times larger than that by a conventional feed-screw mechanism for the same input torque. In addition, the generated compressive force was maintained while the compressive motion was interrupted. These facts confirm the advantage to use RDRLCM for compression test devices as well as for press forming machines.
Non-Contact Measurement of Nugget Size of Spot Welding Using Focused Air-Coupled Ultrasound
Authors: Xu Chen Yan , Ihara Ikuo , Kenzaki Kohmei , Takahashi Manabu
Published: August 2011

Spot welding is widely used in the various fields of engineering and industries. Since the size, shape and mechanical properties of a nugget which is a zone melted and re-solidified during welding are closely related to the strength of the welded structure, quantitative evaluations of them are strongly required. In this work, an air-coupled ultrasound technique with focused transducers has been used for non-contact measurements of spot welds of steel plates. One-dimensional scanning in transmission configuration using a pair of focused air-coupled ultrasonic transducers operating with tone burst waves at 0.3 MHz is performed to obtain the amplitude profile of the transmitted ultrasound through the nugget area of a spot weld. A simple method for determining the nugget size from the profile of the transmitted ultrasound is proposed. To verify the validity of the method, calibration samples which imitate spot welds having different sizes of nuggets are prepared and used for demonstrating nugget size determinations. In addition, the proposed method has been applied to evaluate several spot welds fabricated with different electric currents (5 kA – 9 kA).
Inspection on Buckling Mode of Crossed-Rib Reinforced Composite Laminates Panel by Fringe Projection Profilometry
Authors: Lei Zhen Kun , Zhan L. C. , Bai R. X. , Yang F. J.
Published: August 2011

Digital fringe projection profilometry (FPP) is suitable to inspect surface profile of object, with some apparent advantages of non-contact, full-field measurement, simple apparatus, high precision, and real-time profile automation. Four phase-shifted sinusoidal fringe patterns are circularly projected onto the surface of a composite laminates panel reinforced with crossed ribs. Phase shifting method is applied to inspect the surface profile variations during compression. The profile results reveal that different local buckling modes appear at different crossed ribs, where the wave villages locate at the middle and the wave peaks occur at the composite panel ends. From the details of the deflection analysis, it can be seen that the local buckling modes couple with the whole bending of the composite panel. The local buckling modes vary with the applied load and the experimental results are helpful to understand its failure mechanism.
Residual Thermo-Creep Deformation of Copper Interconnects by Phase-Shifting SEM Moiré Method
Authors: Wang Qing Hua , Xie Hui Min , Hu Zhen Xing , Zhang Jing , Sun Jun , Liu Gang
Published: August 2011

The thermo-creep deformation of interconnects related to the residual stress, directly affects their performance and lifetime. In this paper, we proposed an optical method to measure the residual thermo-creep deformation of copper interconnects. This method takes advantages of grating fabrication and the phase-shifting scanning electron microscope (SEM) moiré method. The residual thermo-creep deformation can be acquired through deformation transformation. A one-way grating with frequency of 5000 lines/mm is fabricated on the surface of the copper line in a focused ion-beam (FIB) system. The principal direction of the grating is along the axis of the copper line. The sample is heated in a high temperature furnace under 90 °C for 70 min. The SEM moiré patterns before and after heating are recorded by a field emission SEM in low vacuum. Through the random phase-shifting algorithm, the residual thermo-creep deformation of the copper interconnect line is found to be 500 με. The cause of the tensile strain is analyzed. This work offers an effective technique for measuring the creep deformation of the film lines.
Bending Fatigue Evaluation of Al6061 Alloy by Laser-Generated Surface Wave
Authors: Nam Taehyung , Choi Sung Ho , Lee Tae Hun , Jhang Kyung Young , Kim Chungseok
Published: August 2011

The bending fatigue of Al6061 alloy has been evaluated by the acoustic nonlinearity of laser-generated surface wave. The surface wave is very attractive for field applications since it enables to pulse and receive signals at the same surface of materials, and has strong acoustic nonlinear effects on the surface. A relative acoustic nonlinear parameter was measured successfully on the surface of fatigue-damaged aluminum 6061 alloy. The results show that the acoustic nonlinear parameter increased with fatigue damage accumulation in relation to dislocation evolution. Consequently, this study suggests that the acoustic nonlinearity technique of a laser-generated surface wave can be potentially used to characterize surface damage resulting from bending fatigue.
Effects of Magnetizations on Three Dimensional Magnetic Flux Density of Pre-Cracked Medium Carbon Low Alloy Steel (JIS S45C)
Authors: Kida Katsuyuki , Santos Edson Costa , Honda Takashi , Koike Hitonobu , Rozwadowska Justyna , Uryu Megumi , Houri K. , Tanabe Hirotaka
Published: August 2011

Fatigue failure of steel occurs when cracks form in a component and continue to grow to a size large enough to cause rupture. In order to understand the crack initiation and propagation phenomena, non-destructive evaluation methods that can be correlated to in-situ measurements around the crack tips are necessary. In the present work, we developed a scanning Hall probe microscope (SHPM) equipped in a GaAs film sensor to observe fatigue cracks at room temperature in air while they were growing. Medium carbon low alloy steels specimens (JIS S45C) were used in the experiments. Only the area around the crack tip was magnetized and the changes at the crack tips were observed.
Effect of Grain Size on Vickers Microhardness and Fracture Toughness in Calcium Phosphate Bioceramics
Authors: Tolouei R. , Ramesh Singh , Tan Chou Yong , Amiriyan Mahdi , Teng Wan Dung
Published: August 2011

Grain size dependences of Vickers microhardness and indentation fracture toughness in fully dense hydroxyapatite bioceramics without additives were studied. The nanostructure and highly pure Hydroxyapatite powders produced by wet chemical precipitation method were used as starting material. After uniaxial and cold isostatic pressing, the green HA samples sintered at temperatures ranging from 1000 °C to 1300 °C with one minute holding time. Dense compacts with grain sizes in the nanometer to micrometer range were processed. The average grain size of HA compact sintered at 1000 °C was around 500 nm. Grain size increased to 3 µm when the compacts were sintered at a higher temperature. The average microhardness value of sintered HA decreased with an increased in grain size. Indentation fracture toughness for HA compacts of 700 nm grain size was 1.41±0.4 MPa.m1/2 which is similar to fracture toughness of human cortical bone.
Experimental Micromachining of Silicon with Nd-YAG Laser
Authors: Mon Thet Thet , Muhamad Khairul F. , Ahmad Asnul H , Mohid Zazuli
Published: August 2011

This research centers on experimental laser-micromachining of silicon using solid state pulsed Nd:YAG laser. The laser is equipped with 3-axis controllers with resolution of 1 µm. The main objective is to find out the possibility of using this laser machining system to fabricate a micro feature on silicon. Simple straight lines were generated on silicon surface. The two process parameters – the laser traverse speed and pulse energy- were considered in the experimental design. Two forms of experiments were carried out: (1) processing with air assist gas and (2) processing without the assist gas using the same experimental design. Standard full factorial design of 3kwas used to design the experiments. Repeatability of the machine and nonlinearity were taken into account in the design by adding center points. Sequence of experiments was also randomized. Statistical analysis of experimental results could not show any significant factor. However, the surface plot did provide general information on desirable regions for the response line width, which was consistent with the published results. Micrograph study of the featured lines revealed that the laser processing without the assist gas produced preferable results.
High Frequency Acoustic Signal Analysis for Internal Surface Pipe Roughness Classification
Authors: Hafizi Z. M. , Nizwan Che Ku Eddy , Reza M.F.A. , Johari M.A.A.
Published: August 2011

This research highlights a method of acoustic emission analysis to distinguish the internal surface roughness of pipe. Internal roughness of pipe indicates the level of corrosion occurring, where normally it is difficult to be monitored online. Acoustic Emission (AE) technique can be used as an alternative solution for corrosion monitoring in pipes, especially for complex pipelines that are difficult to achieve by other monitoring devices. This study used a hydraulic bench to provide fluid flow at two different pressures in pipes with different internal surface roughness (rough and smooth). The main source of acoustic emission was from activity in the control valve, coupled with high pressure water flow friction on the surface of the pipe. The signal from these sources was detected by using the AED-2000V instrument and assisted by the Acoustic Emission Detector (AED) software. The time domain parameter; root mean square, RMS amplitude were processed and compared at different pressures for each type of internal pipe roughness at ten different locations. It was observed that a unitless Bangi number, AB, derived from RMS values, can be used for discriminating different level of internal surface roughness. Internal surface pipe can still be considered as smooth if AB value is above 1.0.
Simultaneous Force and Temperature Sensor Using Small-Diameter FBGs
Authors: Liu Rong Mei , Liang Da Kai , Hu Xing Liu
Published: August 2011

In order to decrease the influence on mechanical performance of smart composite, small diameter optical fibers are usually preferred as strain sensors. Therefore, fiber Bragg gratings in small diameter were manufactured. In applications, the FBG measures both strain (or force, pressure, displacement) and thermal expansion. In order to overcome this inconvenience and to measure both parameters at the same time and location, a simple temperature insensitive force sensor was proposed. A pair of small-diameter FBG was attached on a uniform strength beam. One of the FBG was affixed on the upper surface of the cantilever, and the other one on the bottom. The central wavelength shifts of the two FBGs are proportional to load value F and –F respectively. Therefore, coefficient matrix is well conditioned. The force and temperature in sensing point could be discriminated. Experiments were carried out to study the force and temperature cross sensitivity. Experimental results match the theoretical ones well. The temperature and force were calculated and the errors were 2% and 7% respectively.
Development of a Gamma-Ray Process Tomography System for Hydrodynamic Characterisation of Multiphase Reactors
Authors: Jaafar Abdullah , Said Mohd Khairi Mohd , Rahman Nur Aira Abdul , Mohd Salzali , Shari Mohamad Rabaie , Yussop Nolida , Soh Syirrazie Che , Saad Norizam , Hassan Hearie , Mustapha Mahadi , Mahmood Airwan Affandi
Published: August 2011

Gamma-ray computed tomography (CT) is a powerful non-invasive imaging technique for viewing an object in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT technique revolutionised the field of medical diagnostic imaging because it provides more detailed and useful information than any previous non-invasive imaging technique. The method is increasingly used in industrial fields. This paper describes the development of a gamma-ray computed tomography system for imaging and visualising of industrial multiphase reactors. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. Penetrating radiation from an isotopic gamma-ray source of Cs-137 and a bank of NaI(Tl) scintillation detectors in combination with a dedicated mechanical gantry set-up were used to construct the CT system. During scanning, the movement of the detector’s bank and rotation table is controlled by a LabView-based software. The software is also designed to control all associated nuclear electronics equipments and finally to acquire gamma-ray transmission data. The image reconstruction is performed by using Expectation-Maximisation (EM) and Alternating-Maximisation (AM) algorithms written in Visual-Fortran programming language. Several physical phantoms to simulate industrial multiphase process columns and reactors were scanned using this CT scanner. Some of the reconstructed images are presented in this paper.
A New Moiré Grating Fabrication Technique Using Hot Embossing Lithography
Authors: Tang Min Jin , Xie Hui Min , Zhu Jian Guo , Chen Peng Wan , Zhang Qing Ming , Li Xiao Jun
Published: August 2011

Moiré grating is a basic optical component, and can be used in various moiré methods. The conventional grating fabrication technology is based on photolithography and holographic interferometry, however, it requires complex optical components and is very difficult to put into practice. In this study, nanoimprint lithography (NIL), or rather, hot embossing lithography (HEL), is proposed for producing high frequency grating. Compared with silicon mold, holographic moiré grating mold costs less and is not easy to break, thus is chosen to be the mold in HEL. Using this mold and the hot embossing system, the grating structure can be transferred to the polymer after HEL process. Through a number of experiments, the process parameters were optimized and gratings were successfully fabricated. The multi-scale morphology of the fabricated gratings was then characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and moiré interferometry. The microscale images observed by AFM and SEM show the regulate dots with equal spacing and the macroscale moiré patterns illuminate the excellent qualities of fabricated grating in a large area. The successful experimental results demonstrate the feasibility of the grating fabricated by HEL for the moiré measurement.
Experimental Study on Displacement and Strain Distributions of Bone Model with Dental Implant
Authors: Morita Yasuyuki , Matsushita Yasuyuki , Todo Mitsugu , Koyano Kiyoshi
Published: August 2011

For normal healthy teeth, the percussive energy generated by mastication is attenuated by the periodontal ligament at the healthy bone/natural tooth interface. However, when a natural tooth must be replaced by an implant because of damage or disease, the ligament is lost and the implant will transmit the percussive forces to the bone directly. Studies have evaluated the deformation distribution of the alveolar bone in the vicinity of implants using finite element analysis and photoelasticity. However, finite element analysis requires clinical verification or a determination of material properties, and photoelastic materials generally have material properties and structure quite different from those of actual bone. Therefore, this study examined the deformation distribution around dental implants in cortical/cancellous bone experimentally using sawbone cortical/cancellous bone models. Dental implants were placed in the bone models and the displacement distribution was measured using the digital image correlation method, and the strain distribution was visualized under a compressive load that simulated the occlusion force.