36,280 research outputs found
Fatigue analysis-based numerical design of stamping tools made of cast iron
This work concerns stress and fatigue analysis of stamping tools made of cast iron with an essentially pearlitic matrix and containing foundry defects. Our approach consists at first, in coupling the stamping numerical processing simulations and structure analysis in order to improve the tool stiffness geometry for minimizing the stress state and optimizing their fatigue lifetime. The method consists in simulating the stamping process by considering the tool as a perfect rigid body. The estimated contact pressure is then used as boundary condition for FEM structure loading analysis of the tool. The result of this analysis is compared with the critical stress limit depending on the automotive model. The acceptance of this test allows calculating the fatigue lifetime of the critical zone by using the SâN curve of corresponding load ratio. If the prescribed tool life requirements are not satisfied, then the critical region of the tool is redesigned and the whole simulation procedures are reactivated. This method is applied for a cast iron EN-GJS-600-3. The stress-failure (SâN) curves for this material is determined at room temperature under push pull loading with different load ratios R0Ïmin/Ïmax0â2, R0â1 and R00.1. The effects of the foundry defects are determined by SEM observations of crack initiation sites. Their presence in tested specimens is associated with a reduction of fatigue lifetime by a factor of 2. However, the effect of the load ratio is more important
Kajian terhadap ketahanan hentaman ke atas konkrit berbusa yang diperkuat dengan serat kelapa sawit
Konkrit berbusa merupakan sejenis konkrit ringan yang mempunyai kebolehkerjaan yang
baik dan tidak memerlukan pengetaran untuk proses pemadatan. Umum mengenali
konkrit berbusa sebagai bahan binaan yang mempunyai sifat kekuatan yang rendah dan
lemah terutama apabila bahan binaan ini dikenakan tenaga hentaman yang tinggi.
Namun begitu, konkrit berbusa merupakan bahan yang berpotensi untuk dijadikan
sebagai bahan binaan yang berkonsepkan futuristik. Binaan futuristik adalah binaan yang
bercirikan ringan, ekonomi, mudah dari segi kerja pembinaan dan yang paling penting
adalah mesra alam. Dalam kajian ini, konkrit berbusa ditambah serat buangan pokok
kelapa sawit untuk untuk meningkatkan sifat kekuatan atau rapuh. Serat kelapa sawit juga
berfungsi mempertingkatkan ketahanan hentaman terutamanya aspek nilai penyerapan
tenaga hentaman dan nilai tenaga hentaman. Kandungan peratusan serat kelapa sawit
yang digunakan adalah 10%, 20% dan 30% dengan dua ketumpatan konkrit berbusa iaitu
1000kg/m3
dan 1400kg/m3
. Untuk menentukan nilai penyerapan tenaga hentaman dan
nilai tenaga hentaman, ujikaji Indentasi dan ujikaji hentaman dilakukan ke atas sampelïżœsampel yang telah diawet selama 28 hari. Luas bawah graf tegasan-terikan yang
diperolehi daripada ujikaji Indentasi merupakan nilai penyerapan tenaga hentaman bagi
sampel konkrit berbusa. Untuk ujikaji hentaman, keputusan ujikaji dinilai berdasarkan
nilai tenaga hentaman untuk meretakkan sampel yang diperolehi daripada mesin ujikaji
dynatup. Secara keseluruhannya, hasil dapatan utama bagi kedua-dua ujikaji
menunjukkan sampel yang mengandungi peratusan serat kelapa sawit sebanyak 20%
mempunyai nilai penyerapan tenaga hentaman dan nilai tenaga hentaman yang tinggi.
Serapan tenaga maksimum adalah sebanyak 4.517MJ/m3
untuk ketumpatan 1400kg/m3
.
Ini menunjukkan ketumpatan 1400kg/m3
berupaya menyerap tenaga lebih baik
berbanding ketumpatan 1000kg/m3
. Manakala untuk nilai tenaga hentaman maksimum
adalah sebanyak 27.229J untuk ketumpatan 1400kg/m3
. Hasil dapatan tersebut menunjukkan ketumpatan 1400kg/m3
dengan peratusan serat sebanyak 20% berupaya
mengalas tenaga hentaman yang lebih banyak sebelum sampel retak. Kesimpulannya,
peningkatan ketumpatan konkrit berbusa dan pertambahan serat buangan kelapa sawit ke
dalam konkrit berbusa dapat meningkatkan ciri ketahanan hentaman konkrit berbusa
khususnya aspek nilai penyerapan tenaga hentaman dan nilai tenaga hentaman
Model Checking with Program Slicing Based on Variable Dependence Graphs
In embedded control systems, the potential risks of software defects have
been increasing because of software complexity which leads to, for example,
timing related problems. These defects are rarely found by tests or
simulations. To detect such defects, we propose a modeling method which can
generate software models for model checking with a program slicing technique
based on a variable dependence graph. We have applied the proposed method to
one case in automotive control software and demonstrated the effectiveness of
the method. Furthermore, we developed a software tool to automate model
generation and achieved a 35% decrease in total verification time on model
checking.Comment: In Proceedings FTSCS 2012, arXiv:1212.657
Integrated Process Simulation and Die Design in Sheet Metal Forming
During the recent 10-15 years, Computer Aided Process Planning and Die Design
evolved as one of the most important engineering tools in sheet metal forming, particularly in
the automotive industry. This emerging role is strongly emphasized by the rapid development
of Finite Element Modelling, as well. The purpose of this paper is to give a general overview
about the recent achievements in this very important field of sheet metal forming and to
introduce some special results in this development activity. Therefore, in this paper, an
integrated process simulation and die design system developed at the University of Miskolc,
Department of Mechanical Engineering will be analysed. The proposed integrated solutions
have great practical importance to improve the global competitiveness of sheet metal forming
in the very important segment of industry. The concept described in this paper may have
specific value both for process planning and die design engineers
Winning customer loyalty in an automotive company through Six Sigma: a case study
Six Sigma is a disciplined approach to improving product, process and service quality. Since its inception at Motorola in the mid 1980s Six Sigma has evolved significantly and continues to expand to improve process performance, enhance business profitability and increase customer satisfaction. This paper presents an extensive literature review based on the experiences of both academics and practitioners on Six Sigma, followed by the application of the Define, Measure, Analyse, Improve, Control (DMAIC) problem-solving methodology to identify the parameters causing casting defects and to control these parameters. The results of the study are based on the application of tools and techniques in the DMAIC methodology, i.e. Pareto Analysis, Measurement System Analysis, Regression Analysis and Design of Experiment. The results of the study show that the application of the Six Sigma methodology reduced casting defects and increased the process capability of the process from 0.49 to 1.28. The application of DMAIC has resulted in a significant financial impact (over U.S. $110â000 per annum) on the bottom-line of the company
Towards an Operational Definition of Lean Construction Onsite
Through literature review and drawing from a combined professional experience of over 20 years of lean construction implementation, this paper investigates the key success factor for the automotive industryâs uptake of lean production to see what the construction industry can derive from it. The paper concludes that there exist a variety of definitions of lean, but no existing definition is yet satisfactory to describe lean construction in a rigorously testable method. This is a major obstacle to the successful deployment of lean construction especially when the industry does not have a standard benchmark of âwhat a lean site looks likeâ. It recommends a small-scale replication of the International Motor Vehicle Programme (IMVP) led International Automotive Plant Study (IAPS) in construction. This will be in aid of developing an operational definition of lean construction, in line with Demingâs understanding, in the form of a lean site assessment tool contributing to a Lean Index. A statistical study is also suggested to establish correlation between the degrees of lean application (Lean Index) and project performanc
Recent Achievements in Numerical Simulation in Sheet Metal Forming Processes
Purpose of this paper: During the recent 10-15 years, Computer Aided Process Planning and Die Design evolved as one of the most
important engineering tools in sheet metal forming, particularly in the automotive industry. This emerging role is strongly emphasized by
the rapid development of Finite Element Modelling, as well. The purpose of this paper is to give a general overview about the recent
achievements in this very important field of sheet metal forming and to introduce some special results in this development activity.
Design/methodology/approach: Concerning the CAE activities in sheet metal forming, there are two main approaches: one of them may
be regarded as knowledge based process planning, whilst the other as simulation based process planning. The author attempts to integrate
these two separate developments in knowledge and simulation based approach by linking commercial CAD and FEM systems.
Findings: Applying the above approach a more powerful and efficient process planning and die design solution can be achieved radically
reducing the time and cost of product development cycle and improving product quality.
Research limitations: Due to the different modelling approaches in CAD and FEM systems, the biggest challenge is to enhance the
robustness of data exchange capabilities between various systems to provide an even more streamlined information flow.
Practical implications: The proposed integrated solutions have great practical importance to improve the global competitiveness of sheet
metal forming in the very important segment of industry.
Originality/value: The concept described in this paper may have specific value both for process planning and die design engineers
Validating foundry technologies for extended mission profiles
This paper presents a process qualification and characterization strategy that can extend the foundry process reliability potential to meet specific automotive mission profile requirements. In this case study, data and analyses are provided that lead to sufficient confidence for pushing the allowed mission profile envelope of a process towards more aggressive (automotive) applications.\ud
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