bluuebunny/crossref_metadata_2025 huggingface dataset:
Strengthening Proposals for the Trigonio Tower at the City Walls of Thessaloniki
Authors: Delizisi Vasiliki , Axiotidou Matina , Doudoumis Ioannis N. , Ignatakis Christos
Published: October 2010

The Trigonio tower, constructed in the 15th century for fortification reasons, is part of the city walls of the old town of Thessaloniki. The tower is a cylindrical masonry building and has been considered as part of the cultural heritage of humanity by the UNESCO World Heritage Committee. Today it presents some major damage to its load bearing system, including intense cracking, moisture damage and disintegration of mortar, bricks and stones. An extensive research study for the evaluation of the tower’s bearing capacity, as well as for the suggestion of efficient strengthening interventions was held, in order to effectively prolong its expected lifetime. To this purpose, refined analytical models of 3D finite elements have been formed and used for the estimation of the elastic and inelastic tower’s response to gravity and seismic loads. Results’ evaluation of several static and dynamic analyses showed that the tower’s stability is not at risk under the action of gravity loads in general, but it’s bearing capacity under strong seismic excitations is questionable, thus becoming obvious the necessity of strengthening interventions. An invertible intervention of strengthening the tower with proper sets of external pre-stressed steel rings was also examined. Linear (elastic) analyses showed that they cannot sufficiently evaluate the effectiveness of this strengthening process. Inelastic analyses, using material laws of Drucker-Prager’s type, showed that the use of prestressed steel rings can significantly reduce the plastic strains’ appearance and therefore the cracking in the masonry walls of the monument.
The Research on the Rust of Reinforced Bar and the Strengthening Measures to the Existed R.C. Frame nearby the Sea
Authors: Miao Ji Jun , Qi Bo , Liu Yan Chun
Published: October 2010

The netlike cracks along the rebars at the bottom of concrete slabs as well as the circular cracks around the columns and beams were found in an underground park, which is a cast-in-site concrete frame. The building was about 300 m away from the sea.
The influencial factors which can cause rust of the rebars, such as concrete carbonization, chloride ion (Cl-1) content, and design & construction measures, were analyzed respectively. The in-site inspections and X-spectrum analysis of concrete specimens drilled from the R.C. members were conducted. The concrete carbonization depth and the concrete protection layer were also collected.
In order to find out the main influence factor, steps were carried out as following: at first, according to comparison with the data of calculation and inspection results, the formula for the partial carbonization depth was modified to be used at high humidity environment. Then, the weight ratio of Cl-1 in the drilled R.C. members was 0.02%~0.07% and was lower than the required index 0.1% set by department of construction of Shandong province (DBJ14-S6-2005). The thickness of the concrete protection layer was measured and found to be thinner than the standard set by DBJ14-S6-2005, so as the main reason was identified at last.
To ensure the safety and durability of the building, strengthening measures were brought forward with consideration of the results from both the theoretical calculation and the inspections. The rusted concrete protectionion layer was removed and the anti-rust reagent was brushed when the rusted rebar was cleansed by special machine which can meet the durability requirements. The carbonic fibres reinforcement polymers were stuck on the new concrete protection layer which can provided the bearing capacity. The measures can be a good reference for the same project.
Stabilization and Strengthening the Foundation of the Two Entrance Gates of the Holy Shrine of Imam Reza (PBUH)
Authors: Homami Peyman , Golabchi Mahmood
Published: October 2010

This paper presents the structural analysis and constructional method for the stabilization and strengthening of the foundation of the two entrance gates in Holy Shrine of Imam Reza (PBUH). The holy shrine of Imam Reza (PBUH) is a great complex in the city of Mashhad in Iran. It was founded nearly 1000 years ago and has developed and become extensive through the times. There are several entrances and wide courts around the oldest section in the centre of the complex. Recently, the extension scopes of this complex, required excavation and construction in the basements near the two main gates, called Saat and Naghareh Khaneh Edifice. These activities, near the 400 years old edifices, needed special mobilization, like, monitoring the historical buildings and strengthening their foundations. A deep study was performed, which pursued two purposes. The first purpose was to strengthen the foundation of the buildings and the second was to make a tunnel through the foundation of the buildings because of some operational benefits for the client. At the first glance these two purposes, seemed contradictory, but finally, a new structural system for the foundation were designed and built, which was able to carry the superstructure loads to the ground while a wide tunnel was constructed as well. Special scheduled sequences of construction were prepared, which was flexible and sufficiently reliable so as to overcome any undesirable circumstances and obstacles. Monitoring the buildings behaviour during the constructional phase was conducted to assist the execution directions. This project was carried out successfully and it is in use.
Blasting near Old Foundations and Strengthening of Foundation Walls for the Headquarters of the Ministry for Foreign Affairs of Finland
Authors: Avellan Kari
Published: October 2010

Designed by architect C. L. Engel (1778 – 1840), the Naval Barracks facility was originally built in the 1820´s for the Russian Navy and also served as a shipyard. The building of national heritage is a prime example of neo-classical architecture in Helsinki. Strengthening and underpinning work for this structure was realised from 1985 to 1988. It was a part of the larger renovation project, where the building was made suitable for the Ministry for Foreign Affairs of Finland. The purpose of underpinning was to realise a new basement in its eastern part as well as to lower the basement floor level in other sectors. The ground engineering duties covered geotechnical and structural designs of temporary and permanent structures from the basement up to the ground floor.
Strengthening of Historical Masonry Buildings with Fiber Reinforced Polymers (FRP)
Authors: Kheyroddin A. , Saghafi M.H. , Safakhah S.
Published: October 2010

The historical masonry buildings form widespread spectrum of existing buildings in IRAN. destruction on structures illustrate that historical masonry buildings have maximum damages due earthquake, in addition they don't actuate properly about seismic behavior (the main reason of this is lack of proper ductility). Shear of the masonry walls, is the only structural element of these type buildings, undertake gravity load and lateral load. This is the main reason that leads to researchers think over techniques about improvement and strengthening the walls, and also leads to experiencing real samples and scaled models.
In this essay, at the beginning was introduced a method about modeling finite elements unreinforced masonry (URM) wall by using of software (ANSYS).
In order to verifying the correctness of modeling, it's require to do experimental test on a sample of wall and then that wall should be modeled by illustrated method. Then correctness of modeling method and analyzing method should be verified by comparing the result of numerical modeling with the result of modeling experimental. The experimental model has been examined at Shiraz University. The result of numerical modeling and analyzing illustrate that lateral load-displacement curve is stiffer than experimental curve. And lateral load carrying capacity has precision about 99.28 percent, and lateral displacement has precision about 94.1 percent. also the numerical results agree reasonably well with the experimental results.
In the next stage the masonry walls are strengthened with Carbon Fiber Reinforced Polymer sheets (CFRPs). five different strengthening methods have been used with different thickness. The strengthened walls are affected by vertical loads and in-plane shear. It is found that the critical loads, the critical displacement, the ultimate loads, the ultimate displacements and the ductile coefficients of the masonry walls strengthened with CFRPs improve remarkably.
Study on Effect of FRP Reinforced Manners on Seismic Performance of Concrete Frame Structure
Authors: Peng Ya Ping , Ma Ming , Chen Ming Xiu
Published: October 2010

Many studies showed that FRP bonded to the concrete beams and column surface can effectively enhance the mechanical properties of members, and FRP reasonably bonded to the beam-column joint area can significantly improve the seismic performance, but not enough studies have been carried out on the overall mechanical properties in structure after the framework members are partially covered with FRP. In this Paper, based on the seismic demand analysis of the concrete frame structure, as well as FRP seismic enforcement strategy, a fiber attachment method has been proposed for FRP seismic reinforcement framework. Taking a two-layer dual-span plane framework as an example, nonlinear static analysis has been carried out on FRP-reinforced framework, the capacity spectrum method has been adopted to assess the seismic performance of reinforced framework and the impact of different FRP-reinforced methods on structural seismic performance has been discussed. The results showed that the method of moderate shear-resistance reinforcement in the joint core area, as well as the beam-column plastic hinge area, can effectively improve the seismic performance of the framework, the application of GFRP reinforcement features higher cost-performance ratio, and the FRP bonding at ± 45º in the joint core area can better the reinforcement effect.
Bond between Concrete and Multi-Directional CFRP Laminates
Authors: Sena-Cruz José , Barros Joaquim , Coelho Mário Rui Freitas
Published: October 2010

Recently, laminates of multi-directional carbon fiber reinforced polymers (MDL-CFRP) have been developed for Civil Engineering applications. A MDL-CFRP laminate has fibers in distinct directions that can be arranged in order to optimize stiffness and/or strength requisites. These laminates can be conceived in order to be fixed to structural elements with anchors, resulting high effective strengthening systems. To evaluate the strengthening potentialities of this type of laminates, pullout tests were carried out. The influence of the number of anchors, their geometric location and the applied pre-stress are analyzed. The present work describes the carried-out tests and presents and analyzes the most significant obtained results.
Lightweight Ribs for the Strengthening of Single Leaf Vaults Undergoing Seismic Actions
Authors: Ferrario Luca , Marchina Egidio , Marini Alessandra , Preti Marco , Giuriani Ezio
Published: October 2010

In this paper the behavior and the collapse mechanism of single leaf vaulted structures undergoing seismic loads are discussed, and an innovative technique based on the use of lightweight ribs is proposed. The efficiency of the solution is verified by means of non linear numerical analyses on a strengthened single leaf vaulted structure. The numeric model is validated through comparison with the results of experimental tests performed on lightweight ribs subjected to cyclic, unsymmetrical load conditions.
Analysis of Strengthening Methods for Retained Exterior Walls during a Structural Retrofit
Authors: Ouyang Yu , Hu Ying
Published: October 2010

A three-story old building made up of masonry and wood will be retrofitted to be a new 14-story building, retaining two exterior walls and removing all internal members. To prevent the retained walls form deforming severely or collapse during the retrofit is necessary. The finite element analysis software, ANSYS, is used to calculate the responses of the retaining walls under possible loading conditions. The original retrofit proposal for the old building is refined based on the calculation results.
Retrofitting and Strengthening Design for the Former Yihe Spinner Factory in Shanghai
Authors: Ouyang Yu , Yi Yu
Published: October 2010

The building of the formerly Yihe Spinner Factory in Shanghai is a protected. To ensure its serviceability, appropriate retrofitting is necessary. Structural analysis based on the inspection result was performed. It is shown that the bearing capacity or the ductility of some members in the original structure as well as the retrofit proposal are inadequate. Strengthening design was then performed. The effect of the subsequent retrofitting process on the strengthened structure was analyzed. The historical building is then properly protected and the new manufacturing requirements are meet through the retrofitting and strengthening design. The proposed methods can serve as references for relative research or engineering practices.
The Use of High-Strength Composites in the Reinforcement of Timber
Authors: Kasal Bohumil , Heiduschke Andreas
Published: October 2010

The use of high-strength composites in the reinforcement of structural timber has been documented to enhance the strength and stiffness of wood structural members. Global reinforcement is applied over the entire surface of the reinforced member. Local reinforcement is a targeted strengthening of highly-stressed zones susceptible to failure. Both types of reinforcement enhance the capacity of the reinforced members and mitigate brittle failure modes. This paper presents an overview of the application of fiber-based composites in the reinforcement of beams, columns and connections of timber structures and discusses the state-of-the-art technologies in reinforcement. The applications are illustrated on the reinforcement of beams, arches, frames and beam-to-column connections.
Design of the Seismic Upgrading of the Tambour of the S. Nicolò’s Church in Catania with the DIS-CAM System
Authors: Di Croce M. , Ponzo Felice C. , Dolce Mauro
Published: October 2010

The high seismic vulnerability of several monumental masonry buildings can be ascribed to the low strength of the materials employed, to the presence of wide openings and slender panels and to the high stress due to both vertical and horizontal seismic forces. A new upgrading system, named DIS-CAM (DISsipative Active Confinement of Masonry) was proposed to design the seismic upgrading of the tambour of the dome of the S. Nicolò’s church in Catania (Italy). The technique, that can be considered reversible and a not invasive, is based on a rocking-damper system, in which the rocking and the re-centring capacity are provided by the behaviour of masonry panels, while the dissipation capacity is mainly relied upon hysteretic elements stressed in flexure beyond their elastic limit. In this paper, the design of the scaled model’s seismic upgrading is presented and the main outcomes of preliminary numerical analyses carried out on the tambour, without any reinforcement and retrofitted with the DIS-CAM system, are discussed.
The S. Marco Church in L’Aquila: Provisional Interventions after the 2009 Abruzzo Earthquake
Authors: Carraro Mariano , Ghedina Tiziano , De Sabbata Alessandro , Modena Claudio , Casarin F. , Benetta Dalla M.
Published: October 2010

The 6th of April 2009 a strong earthquake (rated 5.8 on the Richter scale) struck the Abruzzo region in central Italy, causing hundreds of casualties and devastating the historical city of L’Aquila and several small towns in the area. The toll in terms of structural damage was enormous, also considered that a vast amount of buildings was made of poorly arranged masonry composed by round pebbles and mortar of scarce mechanical characteristics. In particular, the buildings belonging to cultural heritage (e.g. churches and monumental buildings) were between the structures that suffered more from seismic damage, considered their dimensions, mass and general lack of adequate connections. Few weeks after the seismic event, a church in the historical city centre of L’Aquila, the S. Marco church, was “adopted” by the Italian Veneto Region, which paid and provided the necessary technical support for the first necessary provisional structural interventions. The paper describes the steps undertaken in order to provide the building with the minimum safety conditions necessary to face the aftershocks, and to survive without further collapses to be subsequently retrofitted. A static and dynamic structural monitoring system was also installed in the church since the beginning of the works, in order to control the safety conditions of the area during the execution of the interventions and to assess the damage progression or stationariness.
Behaviors of Historic Masonry Walls Retrofitted with GFRP under Axial Load
Authors: Raongjant Werasak , Jing Meng , Kerdmongkon Ratchaneewan
Published: October 2010

The purpose of this research is to determine the mechanical properties of historic masonry walls retrofitted with Glass Fiber Reinforced Polymer (GFRP) under axial load through experimental method. Four ancient masonry wall specimens were tested under axial load acted at the top surface. Two wall specimens were served as reference without retrofitting. The third wall was retrofitted with GFRP on full surface before loading. The forth wall was strengthened with three GFRP strips before loading. The behaviors of historic masonry walls in Thailand were particular because of their special bond manner and dimension. The tested results demonstrated that the bearing capacity of historic masonry walls was distinctly improved after GFRP strengthening.
Compressive Strengthening of Damaged Historic Masonry Walls Repaired with GFRP
Authors: Jing Meng , Raongjant Werasak , Kerdmongkon Ratchaneewan
Published: October 2010

The purpose of this research is to determine the mechanical properties of damaged historic masonry walls retrofitted with Glass Fiber Reinforced Polymer (GFRP) under axial load through experimental method. Five masonry wall specimens were tested under axial load acted at the top surface. One wall specimen was served as reference without retrofitting. Two walls were retrofitted with GFRP before damage. Other two walls were repaired using epoxy injection and GFRP sheets after predefined damage. The results show that the bearing capacity of historic masonry walls was completely restored and even exceeded the original capacity.
Archeological Excavations: The "Trauma" and other Consequences on Structural Conservation of Buildings and Sites
Authors: Schaffer Yaacov
Published: October 2010

Previous infill, unearthed and archeological excavations have a major influence on the structural and physical status of buildings and ruins in urban and archeological areas. Archeological excavation is like an "anaphylactic shock” on the excavated structure. Mortar, stone and wood quickly change their performance and bring about a dramatic transformation/alteration in the structure's elements and its whole stability. As in a state of anaphylactic shock if you do not intervene promptly the excavated structure can “die off” explicitly and completely disintegrate.
Archeological excavation also reveals peculiar structural elements that were in use but never viewed or studied from the engineering point of view. These elements of the buildings and sites could be either structural connections in strange angles or unstable structure-stone- frames in current day standards and/or static calculations, that did not collapse in the past earthquakes.
Studying this archeological-engineering issue might result in a better understanding and therefore implementation of the conservation of excavated sites and buildings.
Retrofitting and Moving Protection for Historical Buildings in Jinan City
Authors: Zhang Xin , Li Shi Bin , Liu Tao
Published: October 2010

Retrofitting and moving protection for historical buildings have vital historical and cultural value for they concern both the development of human society material civilization and the continuation of human cultural heritage. Jinan City is ranked among the second group historic and cultural cities of China, where has many valuable historical buildings. The urban construction advances by leaps and bounds in Jinan City since the nineties, which brings tremendous challenge for the protection of historical buildings. The state of the art of protection and retrofitting for the historical buildings in Jinan City is summarized. Three protection schemes, namely in situ retrofitting and minimum distance moving protection as well as long distance moving protection, are adopted in Jinan City. Six finished protective projects are discussed from a structure viewpoint. Retrofitting and monolithic moving techniques are presented for different historical buildings according to the style and features as well as requirements, and also the pivotal techniques for improving aseismatic performance are suggested. Some retrofitting details as to members are also introduced. This will be helpful for the protection of historical buildings.
Mortar Replacement Reinforcement Method for Existing Masonry Structures
Authors: Luo Lie , Zhao Ming , Liu Ying
Published: October 2010

For load-bearing capacity reducing of the walls of multi-storey masonry structure caused by the lower mortar strength and quality defects, the mortar replacement method was used to reinforce the perforated brick load-bearing walls. The strength of mortar used for replacing, the depth of replacement, construction methods and quality control have been studied. The reliability of this method is verified by testing in situ including axial compression test and double brick double-shear test for reinforced brick masonry. This method could be also used in reinforcement for the historical masonry buildings.
On 4R Principle in the Rehabilitation of Concrete Historic Buildings
Authors: Xiao Jian Zhuang , Li Wen Gui , Tawana M.M.
Published: October 2010

vThe 4R principle refers to reduce, reuse, recycle and regeneration, which should be implemented in the process of concrete treatment. In terms of the special micro-structural properties and self-repairing capacity, concrete is one kind of regenerative construction materials. Through proper handlings, self-repairing (crack close-up) of concrete cracks is possible in the concrete hydration damaged region. Due to the effect of heterogeneous nucleation and subsequent crystal growth of calcium hydroxide, a better bonding strength forms interlocking the new and old concrete interfaces. A proposal on the relationship between the self-repairing, regeneration function of concrete and the rehabilitation of historic buildings is suggested, this is based on the formed process of the bonding strength of the interfaces and the function on concrete repairing. Besides the constitution and features of the microstructure of concrete, the relationship between the micro-structure and the macro-mechanical property is also investigated in this paper
Seismic Retrofitting of Historic Masonry Buildings – Case Study
Authors: Santhakumar A.R. , Mathews M.S. , Thirumurugan S. , Uma Rao
Published: October 2010

Masonry heritage building built during early part of 19th century have characteristic colonial architecture using masonry walls and jack arch roofing supported on steel beams. They are highly vulnerable to failure during earthquakes. This paper describes a methodology to quantify their vulnerability and then based on this a scheme of structural retrofitting is suggested. The aim of this presentation, through 4 case studies of buildings located in Delhi, India, is to exemplify various aspects of analysis, design and execution methodology of the retrofitting scheme for such important heritage structures. The assessment of vulnerability is based on its location, codes of practice with respect to materials and loading. The main challenge in choosing the appropriate retrofitting scheme lies in retaining the architecture and aesthetics. Also the retrofitting has to be completed in the least possible time causing minimum disturbance to the occupants. This has been achieved through a combination of Ferro-cement bands and FRP sheets. The execution of retrofitting was considered to make use of available local materials and expertise. The building is analysed in detail and the areas where stress concentration takes place is further strengthened.
Strike a Balance - Repair or Replace?
Authors: Leung Eddy S.T. , Yeung Evita S. , Chan S.W.
Published: October 2010

The preservation and conservation of deteriorated historical structures is always a difficult but challenging task. Theoretically, all significant historic structures should be conserved and saved from being removed or discarded. Practically, this ideal may not always be achievable for all decayed components of the historic structures. Sometimes their conditions are too bad to be reasonably repaired to a safe state. On the other hand, replacement is not the only resort for all the damaged relics. There are situations that these relics should better be preserved, though more resources will have to be invested and greater challenge might be encountered in the course of work. This paper attempts to illustrate the deliberation with a case study - the preservation of wooden structures of Chik Kwai Study Hall in Hong Kong, and addresses the considerations in making decision between repair and replacement. Scientific or structural analysis has played a key role in directing our way to the final decision. Methodology used for guiding the whole conservation process will also be discussed.
Development in Laser Polishing of Polycrystalline Diamond Tools
Authors: Wu Qi , Wang Jun
Published: October 2010

Laser polishing is a surface finishing technology for polycrystalline diamond (PCD) tools by removing uneven diamond particles from the diamond film through graphitization, melting and sublimation. While various types of lasers are used for the polishing of PCD tools, pulsed excimer and Nd: YAG lasers are among the most commonly used ones. The current development in laser polishing of PCD tools is reviewed. The reported experimental and modelling studies to improve the process performance are discussed. It reveals that there is a severe dearth of understanding of the process and the associated models for the efficient and effective use of the technology. The direction of future research in laser polishing is finally discussed.
The Research of the Logarithmic Spiral Axis and NC Machining
Authors: Luo Ning , Zheng You Yi , Han Guo Tai , Jiang Ke
Published: October 2010

The characteristics of surface connection include high fatigue strength, high centering ability, easy dismantling and long life. According to these characteristics and based on the analysis of logarithmic spiral equation, the article explores a new technique of the matched logarithmic spiral profile connection to facilitate efficiently by formulating the machining process and analysing the part technology to determine the geometric modeling, tool path and simulation of NC machining graph and to inspect the process of Logarithmic spiral axes CNC Machining Center and CMM.
Mechanism Research on Cylinder Liner Groove of the Ultrasonic Plateau-Honing
Authors: Cheng Quan , Zhu X.J. , Wang Jian Qing , Lu Zhi Meng
Published: October 2010

Surface-supporting length ratio tp is one of the most important parameters to judge the cylinder liner’s surface quality, which has the obvious influence of on engine oil consumption, blow-by and wearing in. Effective peaks-cutted force has been studied, which is the force component of the supersonic platform honing surging force. It explained that the supersonic platform honing can combine the micro-honing and the platform honing, enhance the value of tp, which has the direct sense to the industrial practice.
Improving the Precision of Gear Honing with External Honing Ring Using Diamond Dressing Gear
Authors: Yu Tao , Qian Yu Xia , Dong Ke , Wang Su Yu
Published: October 2010

The gear honing process is a widely used process for gear finishing after heat-treated, and may be divided into the variants “internal-tooth honing” and “external-tooth honing”. External- tooth honing is seldom used in gear finishing due to lower overlapping ratio and relatively low precision. But its process cost is much lower than internal-tooth honing and gear grinding. The paper puts forward a new method to improve the precision of external-tooth honing, i.e. honing ring is profiled by diamond dressing gears, which have the profile of the workpiece to be machined. Meshing and Tooth contact analysis of honing ring profiling has been considered. Meshing equation of profiling process and equation of honing ring tooth flank after profiling are obtained. Experiment testified that it is an applied method and has many advantages.
Post Processing Algorithm of Ultrasonic-Magnetorheological Combined Finishing for Aspheric Surfaces
Authors: Zhang Fei Hu , Yu Xing Bin , Zhang Yong
Published: October 2010

Ultrasonic-magnetorheological combined (UMC) finishing is a new technique for the ultra precision machining of aspheric surfaces, especially for high quality workpieces with small-radius concave surfaces or freeform surfaces. The characteristic of UMC finishing is discussed, and an experimental equipment for UMC finishing with 5 axes is developed. According to requirements of deterministic removal in UMC finishing and the experimental equipment, post processing algorithm for aspheric surfaces is researched. The derivation process and computer simulation result of the algorithm is presented. The error analysis is conducted and the error control method is also proposed. A series of experiments have been conducted, and experimental results show that high quality surfaces can be achieved by the post processing algorithm.
Investigation into the Process of Selective Laser Melting Rapid Prototyping Manufacturing for Space-Curve-Meshing-Wheel
Authors: Chen Yang Zhi , Sun Lei Hou , Wang Di , Yang Yong Qiang , Ding Jiang
Published: October 2010

The Selective Laser Melting (SLM) technique was investigated for manufacturing of Space-Curve-Meshing-Wheel (SCMW) samples by using of self-made SLM equipment. Experimental results show that, the driving and the driven wheels have considerable shape accuracy and size accuracy to commit continuous and stable transmission.
The Relationship between the Distribution Characteristics of Cutting Speed at the Contact-Point and the Surface Quality of Gear Teeth
Authors: Liang Guo Xing , Lv Ming , Gao Xiao Xu
Published: October 2010

In the paper, the vector expression of cutting speed on the contact-points has been obtained by the coordinate transformation. The cutting speed is the contact-point position function which is correlated with contact-line in the process of honing gear. It is diverse along the direction of the tooth depth, so the surface texture of workpiece gear has a visible difference from the top to the root of the tooth. It is showed in the results that the surface roughness value of same tooth has further increscent differences with the increasing honing speed, and the surface of tooth is in the same quality.
An Experimental Study on the Kerf Characteristics of Silicon Cut with Micro Abrasive Air Jet
Authors: Li Quan Lai , Huang Chuan Zhen , Wang Jun , Zhu Hong Tao , Liu Zeng Wen
Published: October 2010

Micro abrasive air jet (MAAJ) cutting technology is being increasingly used in the precision machining of hard and brittle materials, due to its distinct advantages of negligible heat effect zone and small cutting force. In this paper, an experimental study on the kerf characteristics, especially for the effect of cutting parameters on the top edge definition, is presented. It shows that the top kerf edge is straight but not sharp. The top edge definition of the kerf improves with a decrease in the air pressure, while the effect of abrasive flow rate and nozzle traverse speed are hardly discernible. The optimum jet incidence angle for highest top edge definition of the kerf is 60°. The results of this paper may be useful for the cutting parameters optimization in the precision three-dimensional micro-structural machining.
Fabrication of Micro Aspheric Mould Integrated Ultra-Precision Grinding and Magnetorheological Finishing
Authors: Yin Shao Hui , Tang Heng Ning , Yu Jian Wu , Tang Kun , Chen Feng Jun , Xu Zhi Qiang , He Jian Bo
Published: October 2010

This paper deals with one-point parallel grinding and magnetorheological finishing (MRF) polishing of micro glass lens mould. Firstly,the analysis and experiment of one-point parallel grinding are conducted on micro-aspheric mould with 10mm in diameter , after grinding ,the results show that the form accuracy of the micro aspheric mould are 2.538 μm in PVand 0.645 μm in RMS, also the subsurface damages and residual grinding marks are left ;And then , the magnetorheological finishing experiment is counducted, the form accuracy achieves 0.892 μm in PV and 0.287 μm in RMS ,after finishing, the surface quality was improved.
Study on Contact Friction between Polishing Disk and Workpiece during Face Polishing with ANSYS
Authors: Xu Xiao Cun , He Yan Gang , Xin Xiang Kai , Lin Bing
Published: October 2010

Since almost large die surfaces are free-form surfaces, currently, these are almost manually implemented. In order to overcome this barrier, floating polishing is a feasible polishing technology. The contact friction between polishing disk and workpiece is a key problem of floating polishing technology. This paper tries to study the contact friction between polishing disk and workpiece with ANSYS analysis software. At first, the paper focuses on the contact friction between polishing disk and plane workpiece by ANSYS analysis software, then focuses on the contact friction between polishing disk and cylinder and sphere workpiece with the software. The analysis results show the hypothesis of full friction condition is feasible. The research results will be used for developing the floating polishing.
Study on the Friction Behavior of HFCVD Diamond Films on Silicon Nitride Substrates
Authors: Shen Bin , Sun Fang Hong , Yang Guo Dong
Published: October 2010

The friction behaviors of CVD diamond films on silicon nitride substrates are investigated comparing with the uncoated silicon nitride samples. Two types of CVD diamond films, namely MCD and NCD films, are deposited on the silicon nitride substrates using HFCVD method, and then SEM, while light interferometer, XRD and Raman spectra are employed to characterize as-deposited diamond films. The friction tests are carried out in a ball-on-plate reciprocating friction tester, with ball-bearing steel, copper, tungsten carbide and tungsten carbide as the counterpart materials. The results show that the diamond film deposited on silicon nitride substrate has significant effect on reducing the friction coefficient and enhancing the wear resistance. The friction coefficients of MCD and NCD films are around ~0.35 in dry sliding against ball-bearing steel and copper, while for sliding with the tungsten carbide and silicon nitride, the friction coefficients of NCD films even decrease as low as ~0.12 and ~0.08 respectively. The special wear rate of the silicon nitride and NCD film can be estimated as 6.2167×10-5 mm3 N-1 m-1 and 4.03×10-7 mm3 N-1 m-1 with the counterface of silicon nitride. Comparatively, no measurable wear occurs on the worn surface of the MCD film.
Experimental Study of Two-Phase Compulsive Circulation Flows Finishing
Authors: Li Wen Hui , Yang Sheng Qiang , Li Xiu Hong
Published: October 2010

For the precise hole surface, the burr severely affects products’ performance. Considering the specific conditions of the precise hole surface finishing, a new method of two-phase compulsive circulation flows finishing is brought up. Nozzle number, nozzle position, liquid flow, etc. are main factors, which would directly influence finishing effect and efficiency. Affecting rules of main factors are studied by experiments and numerical simulation, which provide basis for thorough research.
Effect of Grinding Process Parameters on Surface Layer Residual Stress
Authors: Xu Ying Qiang , Zhang Tao , Bai Yu Mei
Published: October 2010

Grinding induces tensile residual stresses, which can play an adverse role on the fatigue and wear resistance of the component. In this paper, a calculation model of residual stresses induced by a surface grinding process on a ultrahigh-strength steel workpiece (Aermet100) is presented, which includes the transient heat conduction equation、a thermal elastic-plastic constitutive equation and the Von Mises yield condition. The model giving the energy conducted as heat in the workpiece as a function of the grinding wheel speed, the workpiece speed, and the cutting depth is proposed. It is shown that, for such grinding conditions, the simulation leads to tensile residual stresses which increase with the wheel speed and cutting depths increase. The paper offers an insight into the mechanism understanding of thermal residual stresses induced by surface grinding.
Improving the Sediment Stability of Fluid Magnetic Abrasives Based on Nanometer SiO2
Authors: Sun Huan Wu , Chen Wei Yi
Published: October 2010

The fluid magnetic abrasives (FMA) are a new type of precision finishing abrasives which are developed on the basis of the phase transition phenomenon caused by magnetic field. The sediment stability and agglomerative stability are significant characteristics of FMA, and have a great impact on the finishing capabilities and the final surface roughness value. In order to improve the stability of FMA, a new ingredient based on nanometer SiO2 is proposed, the preparation method and the experimental results are also discussed in this paper.
Researches on Burr Formation in Milling Al-Alloy
Authors: Chen Ming , Rong Bin , Liu Gang
Published: October 2010

Burr formation is a bottleneck of the production line and deteriorates the automation integrity. To this question, investigations were carried out in this paper on the burr formation in milling aluminum alloy (Al-alloy), in order to enhance productivity and workpiece quality by active process control. Milling burr formation were predicted and minimized for the sake of rough machining and finishing operation, using strategies of tool path planning, processing parameter optimization as well as workpiece rigidity strengthening. The conclusions reached in this paper are useful in practice to realize burr-free Al-alloy milling for manufacturing automation.
Research on Thermal Error Modeling of CNC Machine Tool
Authors: Guo Qian Jian , Yang Jian Guo
Published: October 2010

Four key temperature points of a CNC machine tool were obtained in this paper, and a thermal error model based on the four key temperature points was proposed by using based back propagation neural network. A thermal error compensation system was developed based on the proposed model, and which has been applied to the CNC machine tool in daily production. The results show that the thermal error in workpiece diameter has been reduced from 33 to 6 .
The Analysis of Fracture Formation on Exit Edge in Pricision Machining
Authors: Wang Gui Cheng , Shen Qin Xi , Zhu Yun Ming
Published: October 2010

Burrs and fractures are two types of shapes formed on exit edges in pricision machining. They affect the quality of workpiece and the efficiency of prodcution seriously. A finite element model of fracture formation process to simulate the machining process of 2024-T3 Aluminum alloy is proposed. According to simulation results, five stages and variation of shear shain in fracture formation process are analyzed. It is found that shear strain plays an important role in fracture forming process. The method of determination of critical shear strain for fracture forming is proposed from simulation results.
Study on the Optimized Blanking Allowance of Fine-Blanking with Negative Clearance for AISI-1020 and AISI-1045
Authors: Li Jian Hua , Fan Wei Fu , Zhang Zhong Mei
Published: October 2010

The fine-blanking procedure for AISI-1045 and AISI-1020 under the condition of various blanking allowance has been simulated by the DEFORM-2D software, and a large number of fine-blanking experiments have been made. Some key factors, like blanking allowance affecting upon the ejector force, the perfect ratio of fracture and the fracture procedure, are discussed, and the principles for choosing value of blanking allowance are given. In order to reduce ejector force, increase the perfect ratio of fracture and separate scrap from sheet metal easily, a smaller value C of blanking allowance should be adopted whenever possible. The value C of blanking allowance should be chosen according to the mechanism capability. For some types of steels which have good plasticity, a larger value C of blanking allowance should be chosen, so that the work-piece without blanking edge could be obtained. For some types of steels which have poor plasticity, a smaller value C of blanking allowance should be chosen to obtain blanking work-piece with higher quality. Generally speaking, the optimized value of blanking allowance should be from 0.15mm to 0.35mm, and the largest value must be less than 0.5mm.The research result has instructive significance and reference value to improve the quality of work pieces and the perfect ratio of sheared band.
Ultra Smooth Planarization Polishing Technique Based on the Cluster Magnetorheological Effect
Authors: Yan Qiu Sheng , Yan Jie Wen , Lu Jia Bin , Gao Wei Qiang
Published: October 2010

A new planarization polishing method based on the cluster magnetorheological (MR) effect is presented to polish optical glass in this paper. Some process experiments were conducted to reveal the influence of the content of carbonyl iron and the abrasive materials in the MR fluid on the machining effect, and the machining characteristic of polished surface was studied. The results indicate that the surface roughness of the polished workpiece can be reduced rapidly when the strong magnetic field is applied, and ultra smooth surface with Ra 1.4 nm can be achieved while the CeO2 abrasives are used in the MR fluid. The content of carbonyl iron obviously influences the machining effect of this planarization polishing method based on cluster MR-effect. With the increase of the content of carbonyl iron in the MR fluid, the material removal rate improves and the surface roughness reduces rapidly. However, the difference of abrasive material results in various machining effects. As for the K9 optical glass, the CeO2 abrasive is better polishing abrasive than the SiC abrasive in the planarization polishing technique based on the cluster MR-effect.
Application of Laser Shock Processing to Improving the Fatigue Performance of Compressor Blade
Authors: Li Qi Peng , Li Ying Hong , He Wei Feng , Li Wei , Li Yu Qin
Published: October 2010

The vibration strength under allowable value leads to the failure of compressor blade of certain aeroengine. In order to solve the problem, laser shock processing on blade was studied. First, the processed part of blade as well as the laser shock processing (LSP) parameters was established. Second, the influence of LSP and tumbling to the vibrate fatigue capability of blades were researched according to the application of the project. Third, the strengthening mechanism of LSP on improving the fatigue performance of the blade was studied. The results show that, LSP is consistently dependable and can prolong the vibration fatigue life of the blade efficiently. LSP can be placed after tumbling or directly replace it during the manufacturing of blade. The grain refinement, higher hardness and compressive residual stress are the three main reasons that enhance the fatigue capability of blade.
Process Parameters Optimization for Micro-Arc Oxidation of Hot-Dip Aluminum Coating on Stainless Steel
Authors: Niu Zong Wei , Li Zhi Yong , Wang F.F. , Zhang Jia You , Wang Ai Hong
Published: October 2010

Alumina ceramic coating was gained by micro-arc oxidation of hot-dip aluminum film on stainless steel. The main properties indexes of ceramic coating include the thickness, the hardness and the surface roughness. The main process parameters determine above properties include the electric current density, the duty ratio of the pulse, the frequency of the pulse and the action time. The artificial neural network model was established to forecast the properties and optimize the process parameters for the micro-arc oxidation of aluminum film. Experimental results proved that the optimization model has high veracity and can be applied to the choice of process parameters.
Progress in Theory and Application Research on Microscale Laser Shock Peening
Authors: Wei Deng Hui , Zhou Jian Zhong , Huang Shu , Fan Yu Jie , Wang Min
Published: October 2010

Micro-scale laser shock peening (μLSP) is a novel surface modification technique utilizing mechanical effect of shock wave induced by high intensity pulsed laser with micron spots. μLSP can introduce the beneficial residual compressive stress distribution in surface layers of metal with micron-level spatial resolution, and thus enhance wear resistance and fatigue performances of metallic micro-structures. The characteristics and influence factors of μLSP were briefly introduced, and progress in μLSP research fields was reviewed and presented, including laser induced shock pressure, material constitutive relation, changes of mechanical properties and microstructure evolution of materials. Finally, proposals on further investigations of μLSP were brought forward. The systematical characterization will lay the ground work for better understanding the effect of μLSP in microlength level and developing a more practical simulation method.
Numerical Simulation of Temperature Field for Rack Grind-Hardening
Authors: Zhang Ru Bo , Ge Pei Qi , Zhang Lei , Li Bin , Zhao Chao
Published: October 2010

Grind-hardening is a new integrated machining technology which utilizes grinding heat to quench the non-quenched steel directly. In this paper, the technology is applied in the process of rack form grinding. A comprehensive numerical model is developed to simulate the temperature distributions of the rack under the dry grind-hardening conditions with finite element method(FEM). The temperature dependency of the thermal properties, the triangular heat distribution of the heat flux, latent heat and the air convection are taken into account. The simulated hardness penetration depth(HPD) is deduced from the local temperature distribution, time history of workpiece according to martensitic phase transformation theory. This provides a reliable method for the proper selection of process parameters in order to produce enough heat at the contact zone, enabling the treatment of the rack.
Study on Laser-Clad Al/Cr3C2 Compound Powders on the Titanium Alloy Substrate
Authors: Liu Gui Jie , Wang Xin , Li An Jin , Hu Fang You
Published: October 2010

To improve the comprehensive properties of titanium alloy, an experiment of laser-clad (Ti+Cr3C2+Al) has been carried out, using pulsed YAG laser as the radiated source. By optimizing the process parameters, we get uniform, continuous and flawless cladding layer with the composition changes gradient. It is found that cladding layer and the substrate show excellent metallurgical bonding. The microstructure transforms from coarse columnar grains to fine tree-like grains from substrate to top, and a small amount of TiAl and TiC ceramic hardening particles exists. The hardness of the cladding zone increases obviously, the maximum is 1650HV, 2-3 times of the substrate. A white narrow metallurgical bonding zone is formatted at interface between the cladding layer and the substrate.