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Computer aided planning for orthognatic surgery  [PDF]
Matthieu Chabanas,Christophe Marecaux,Yohan Payan,Franck Boutault
Physics , 2006,
Abstract: A computer aided maxillofacial sequence is presented, applied to orthognatic surgery. It consists of 5 main stages: data acquisition and integration, surgical planning, surgical simulation, and per operative assistance. The planning and simulation steps are then addressed in a way that is clinically relevant. First concepts toward a 3D cephalometry are presented for a morphological analysis, surgical planning, and bone and soft tissue simulation. The aesthetic surgical outcomes of bone repositioning are studied with a biomechanical Finite Element soft tissue model.
Achievements of the Family Planning Program in Iran
M Simbar
Journal of School of Public Health and Institute of Public Health Research , 2010,
Abstract: Background and Aim: Rapid growth of Iran's population attracted attention of the authorities after the 1986 national census. This led to population control and family planning programs to be considered as a priority. Appropriate strategies of the family planning program led to a very fast decrease in population growth and fertility indices:; and use of contraceptive techniquies rate increased from 49% in 1989 to 73.8% in 2007. This study aimed at reviewing family planning program in Iran (FPPI) during the last four decades and discussing the reasons for its success, as it can be a guide for future efforts aimed at improving other aspects of reproductive health. Materials and Methods: The method used was systematic reviewing of articles indexed in Medline and University Jihad Scientific Database, reports of the Demographic and Health Project, the Iranian Statistical Center National Censuses, and the Ministry of Health and Medical Education reports on knowledge, attitude and practice. Results: FPPI initiated officially in 1966 faced with limited success. Following the 1986 national census, population control was announced as a public policy, supported by the leaders. A supportive environment was created by mass media. Establishment of the Departments of Population and FP in the Ministry of Health made possible reorganizing family planning services: expanding coverage of PHC services, including FP services; training skilled personnel; providing free contraceptives; and vasectomy and tubectomy services. Involvement of volunteers and NGOs helped in strengthening community actions. In order to develop personal skills, in addition to face-to-face FP counseling in the health centers, FP education in schools, colleges, workplaces, army and pre-marriage classes was also imparted. Promotion of men's participation in FPPI, by providing male methods of contraception, such as vasectomy or condom use, was also considered. There was also cooperation and support on the part of nongovernmental and international organizations. Conclusion: Based on the findings, it may be concluded that the principles of health promotion can explain the FPP achievements in Iran. This model can be used in expanding other reproductive health programs in Iran.
General overview of sheet incremental forming
M. Tisza
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: The aim of this research paper is to give a general overview on sheet incremental forming as an emerging field in small and batch production.Design/methodology/approach: First the historical and literature background of sheet incremental forming will be given, and then some theoretical and practical issues of the incremental forming processes will be described including the research work done by the author at the University of Miskolc. This research is part of an international EUREKA project with the main focus on formability and accuracy in incremental sheet forming.Findings: In this research paper some important findings on the critical wall angle which is a characteristic formability feature in incremental sheet forming will be discussed. New specimen geometry was elaborated to reduce the great amount of experimental work to determine the formability limits. The main conclusions are that in incremental forming the formability is significantly higher compared to conventional sheet forming. The process is very flexible and economic due to the low tool costs.Research limitations/implications: One of the main target areas of further research work is the determination of technological window for sheet incremental forming of various materials and to introduce this novel process into industrial practice.Practical implications: In practical applications besides the economy of the process due to its very low tool expenses, the flexibility should be mentioned which is very important in small batch production and particularly in rapid prototyping.Originality/value: The results achieved within this research work are equally important both from the point of view of theoretical and practical aspects of sheet incremental forming.
Incremental sheet forming process modelling - limitation analysis  [PDF]
M. Pohlak,J. Majak,R. Küttner
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: of this paper is incremental sheet forming (ISF) process modelling. Main attention is paid to limitation analysis. Two kinds of risks are considered: material failure and tool failure. Aim of the current study is to minimize both risks i.e. provide limits for safe manufacturing.Design/methodology/approach: Experimental, numerical and theoretical investigation is performed. The test procedures are designed for determining FLD and forming force components in ISF process. The ISF process is modeled using FEM software LS-DYNA (fully integrated shell elements). In numerical analysis the plastic anisotropy is considered (Hill’s second and Barlat’s higher order yield criteria).Findings: The influence of plastic anisotropy on two formability characteristics - FLD and forming load components is studied. In both cases the effect of plastic anisotropy is found to be significant. It is shown that variation of the Lankford coefficient(s) in range 0.5-3.0 may cause changes on the formability characteristics over ten percent.Research limitations/implications: Limitations on forming angle, complications with considering elastic spring-back.Practical implications: The estimates on forming load components can be used for tooling selection in order to avoid tool failure. The FLD can be used in order to separate safe and unsafe forming areas in ISF process.Originality/value: An approximate theoretical model is proposed (based on Iseki’s model). Incremental sheet forming strategies for determining forming limit diagram (FLD) are pointed out.
Comparison of technology of forming the sheet metal by numerical simulations  [PDF]
I. Pahole,M. Puc,B. Vaupoti?,J. Bali?
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The paper is concerned about the problems in forming low-carbon and stainless sheet metal in parallelon the same tools. It describes the properties of stainless sheet metal and the comparison with ordinary sheetmetal of DC04 quality. Differences in physical properties pose a source of problems occurring in forming bothsheet metals of the same geometry.Design/methodology/approach: Numerical simulation methods of deep drawing have been used for planningthe technology of forming low-carbon and stainless sheet metal. For establishing basic properties of material theconventional testing methods have been used.Findings: The target of researches was to find out what changes have to be made in the forming tools, when thesheet metal from stainless steel is formed.Research limitations/implications: : Comparison of formability of sheet metals was limited only to materialssuitable for use in production of household appliances.Practical implications: The research is practically employed in forming sheet metal parts for household appliances.Originality/value: By the use of the method described it is possible to determine in advance, how the formingtool must be made. Our aim was to make a forming tool suitable for forming sheet metal from stainless andlow-carbon steel. The paper presents actual constructions.
KF Zhang,FX Diao,QF Song,W Wu,KB Chen,TXie Harbin Institute of Technology,Harbin,China,
K.F. Zhang
,F.X. Diao,Q.F. Song,W. Wu,K.B. Chen and T.Xie Harbin Institute of Technology,Harbin,China

金属学报(英文版) , 2000,
Abstract: This study is concerned with the problems of contact in the process of numerical simulation of sheet metal forming in rigid visco-plastic shell FEM. In respect of analysis of sheet deep drawing process,for the tool model described by triangular elements, a kind of contact judging algorithm about the correlation between the node of deformed mesh and the triangular element of a tool is presented. In SPF/DB Lagrangian multiplier method is adopted to solve the contact problem between deformed meshes, and a new reliable practical dynamic contact checking algorithm is presented. As computation examples, the simulation results of metal sheet deep drawing and SPF/DB are introduced in this paper.
Hegde’s instability mechanics for the prediction of forming limit in sheet metal forming  [PDF]
G.S. Hegde,J.R. Nataraj,R. Sridhar
Archives of Computational Materials Science and Surface Engineering , 2009,
Abstract: Purpose: The purpose of the paper is to investigate the Hegde’s instability mechanics for the prediction of forming limit in sheet metal forming.Design/methodology/approach: Hegde’s Instability Mechanics (HIM) paves way for explaining the effects of diffuse instability and localization due to necking in sheet metal forming. For different ranges of stress ratios, the ratio of strain differentials has been computed and hence the forming limits are predicted.Findings: Basing the formulation of HIM on the von Misess yield criterion and applying the interface theory (briefed in appendix) the state-of- the-art purpose is deemed to be well served and demonstrated. Interface theory to explain in simple terms, gives the optimal decision variables in an ‘n’ dimensional hyper-space. The concept of HIM is demonstrated on isotropic and anisotropic materials. The anisotropic materials show better stability than isotropic materials in sheet metal forming. However the geometric instability is analyzed with the assumptions that the thickness stresses are negligible and biaxial state of stress persists in sheet metal forming.Practical implications: The observations are based on the theoretical findings for which the experimental validation exists in the reviewed references.Originality/value: To the sincere knowledge of authors, is both different and unique of its kind in sheet forming mechanics needing horizontal exploration by potential researchers.
Development of the computer-aided process planning (CAPP) system for polymer injection molds manufacturing  [PDF]
J. Tepi?,V. Todi?,D. Luki?,M. Milo?evi?
Metalurgija , 2011,
Abstract: Beginning of production and selling of polymer products largely depends on mold manufacturing. The costs of mold manufacturing have significant share in the final price of a product. The best way to improve and rationalize polymer injection molds production process is by doing mold design automation and manufacturing process planning automation. This paper reviews development of a dedicated process planning system for manufacturing of the mold for injection molding, which integrates computer-aided design (CAD), computer-aided process planning (CAPP) and computer-aided manufacturing (CAM) technologies.
Computer aided planning and navigation for orbito-zygomatic reconstruction  [PDF]
Christophe Marecaux,Matthieu Chabanas,Yohan Payan,Franck Boutault
Physics , 2007,
Abstract: This paper suggests a full protocol of Computer Aided Surgery as previously recommended in literature addressing the challenging task of primary or secondary reconstruction of orbito-zygomatic dislocation. First, on a specifically developed planning software, the best zygoma reduction and orbital boundaries reconstruction to achieve skeletal symmetry are determined. This treatment plan is then transferred to the 3D Navigation Systems within the operating room. After patient's anatomy registration to his preoperative CT scan data, the navigation system allows zygomatic guiding to its planned reduced location and bone orbital volume restoration control. The feasibility of this technique was checked in 3 patients with major orbito-zygomatic deformities. Preliminary clinical results are presented.
Isothermal Gas Forming of Mg Alloy AZ31 Sheet
Yung-Hung Chen,Shyong Lee,Jian-Yih Wang,

材料科学技术学报 , 2002,
Abstract: There have been reports on sheet forming of Mg alloy in industry via the punch and die method; this paper is probably the first formal one for studying the sheet formability of AZ31 employing pressurized gas to press the sheet into a female die cavity at various elevated temperatures. The results indicate it is feasible to form a rectangular box via pressurized gas from extruded sheets of 0.5 and 1.7 mm thick. The formed box has 1:2 depth over width ratio, which should be large enough when dealing with realistic industrial sheet forming parts. Presently, forming a sheet of 0.5 mm thick is considered a technical challenge by industry, and it is conquered as demonstrated in this paper. Gas forming technique applied to Mg alloy is unprecedented and shows potential for industrial utilization.
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