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Various factors, such as process bottlenecks, un-optimized production schedules and imbalance employees' working time, can complicate production processes and operations. These factors, however, have rarely been considered in previous discrete event simulation studies, which typically analyses the impact of available resource capacities on system throughput. By considering the factors, this paper models and analyses the production processes of a soy sauce manufacturing company. The flow of the processes and their processing time were first observed and collected from the real system. The flow logic and behavior were simulated using Arena software. The model was run, verified and validated to measure the current performance of the system, especially on the utilization of available resources. Various 'what-if' scenarios were then analyzed to propose strategies to improve the processes. The analyses show that bottlenecks occur at the moromi and koji processes, imposing the company to extend their operation hours to satisfy the demand of the product. The model helps the company identify the pain point in the production flow and analyze potential actions and its impact on production throughput. [ABSTRACT FROM AUTHOR]

The paper deals with the issues of increasing the efficiency of functioning of synergetic robotic systems by searching for waysto improve the simulationmodels underlying them (increasing the degree of completeness and adequacy). The architecture of a hybrid simulation model is proposed on the example of a basic complex modeа of functioningания of a collaborative process. The model is built according to the modular principle and combines discrete-event modules and real-time modules (dynamic modeling, etc.). The platform solution gives the model maximum flexibility when it is specialized for a specific technological process. The functionality of the model is aimed not only at modeling regular situations, but also allows you to forecast the impact of disturbing factors on the development of the situation and the quality of the joint production process of the operator and robot. The interface of the model allows you to include the operator in the planning process of tactical decisions, due to the possibility of organizing control actions on it by means of the effector system. [ABSTRACT FROM AUTHOR]

Biogas produced through anaerobic digestion (AD) of organic materials attracts the interest of researchers and developers throughout the world as one of the most sustainable ways. Despite its complexity, numerous mathematical models have been developed to represent the biological transformation of these organic waste. Thus, most researchers favor combining these models with simulation software to facilitate building the AD without actual experimental setup as it eases the evaluation and analysis process. This paper presents a wide-ranging review of different types of simulation software used in AD. It can be categorized into two types: equational oriented and sequential modular. These methods provide different benefits to the developers of biogas production in accordance with the objectives of the study conducted. It includes establishing process design criteria that help in equipment sizing, hence easing the estimation of capital and operating costs. This review discusses how different simulations are used on different case studies with different conditions and parameters based on past research achievements. [ABSTRACT FROM AUTHOR]

In this paper, a fully adaptive 3D numerical methodology based on a tetrahedral element was proposed in order to improve the finite element simulation of any metal forming process. This automatic methodology was implemented in a computational platform which integrates a finite element solver, 3D mesh generation and a field transfer algorithm. The proposed remeshing method was developed in order to solve problems associated with the severe distortion of elements subject to large deformations, to concentrate the elements where the error is large and to coarsen the mesh where the error is small. This leads to a significant reduction in the computation times while maintaining simulation accuracy. In addition, in order to enhance the contact conditions, this method has been coupled with a specific operator to maintain the initial contact between the workpiece nodes and the rigid tool after each remeshing step. In this paper special attention is paid to the data transfer methods and the necessary adaptive remeshing steps are given. Finally, a numerical example is detailed to demonstrate the efficiency of the approach and to compare the results for the different field transfer strategies. [ABSTRACT FROM AUTHOR]

Proposed in this paper is a framework of virtual plant model for verification of PLC program by conducting the virtual plant modeling and simulation. The proposed virtual plant model consists of three types of objects: the virtual device model (object model), the intermediary transfer model (functional model) and PLC program (dynamic model). For the implementation of the proposed virtual plant model, this paper employs the I/O model which is based on Automata and Discrete Event System Specifications (DEVS) formalism. By applying an example of the automotive assembly line, nine errors in the PLC code are found and have been revised. With the proposed approach, it will be helpful to reduce the ramp up or down time of the automated manufacturing system. [ABSTRACT FROM AUTHOR]

The article is devoted to methods of expert evaluation. The technology of expert evaluation is presented from the standpoint of precedent structures. In this paper, an aspect of the mathematical basis for constructing a component of decision analysis is considered. In fact, this approach leaves out any identification of their knowledge and skills of simulating organizational and manufacturing situations and taking efficient managerial decisions; it doesn't enable any identification and assessment of their knowledge on the basis of multi-informational and least loss-making methods and information technologies. Hence the problem is to research and develop a methodology for systemic identification of professional problem-focused knowledge acquired by employees operating adaptive automated systems of training management (AASTM operators), which shall also further the theory and practice of the intelligence-related aspects thereof. [ABSTRACT FROM AUTHOR]

There are published articles dealt with the integration of acceptance sampling and supply chain management using simulation models. This paper focus on developing simulation model for 100 % screening in supply chain management and considers supply chain model with the re-ordering system. Whatever be the good items produced, practically there are the possibilities of imperfect items or they might not satisfy the standards of production process. Therefore, it needs rectification. Hence, the researcher applies sampling plans in-between the stage of purchase and production process. Generally, after purchase, the entire lot is being sent to the production process, whereas, in this proposed model, the purchased lot is being sent to sampling inspection. In this stage, if the sampling inspection results are positive and the lot is accepted then only the lot is send it to production process. If the lot is rejected then it is allowed to the acceptance sampling process only after 100% screening. Under 100% Screening Policy the simulation model considers the cost effectiveness in supply chain also using the simulation software Goldsim 12.0. [ABSTRACT FROM AUTHOR]

Modelling and Simulation (MS) is considered very useful in providing information related to the performance of a system. Through MS, we can imitate and project the real state of a method to get information about the time of manufacture. Our research focuses on modelling and simulation with Discrete Event Simulation (DES) and Agent-Based Simulation (ABS) using AnyLogic Software to provide information related to the pesticide production process at PT DAI. The results of this study provide an overview of the production process in 2D with some information such as processing time, machine idle time, and overall system utilization. Processing percentage values obtained from nine work stations in the range 89.93% - 99.99% and overall system utilization with a value of 0.94. [ABSTRACT FROM AUTHOR]

Advances in the processing power of modern computer hardware and the availability of sophisticated simulation software have fostered the use of virtual prototyping techniques in the automotive industry. However, many engineering problems require simulation and optimization computations so complex that it is imperative to utilize parallel computing to solve these problems in reasonable time. In this paper, FETI-INDEED — a parallelized simulation code for sheet metal forming — as well as algorithms for distributed optimizations are examined. Because it is anticipated that increasingly large problems will need to be solved in the future, particular focus is put on scalability aspects of these components. Experimental results are provided for optimizations which were performed on a 300 CPU Opteron cluster. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper discusses various computational tools developed for the numerical simulation of welding processes. The tools can be broadly classified into two groups: Process related tools that facilitate simulation accuracy; Speed and ease-of-use related tools that facilitate simulation and operational efficiency. Process related tools that are discussed include the weld heat flux specification, the weld path and weld fillers that are created in conjunction with the moving heat source. Some of the issues associated with the weld heat flux computation are: correct choice of weld flux expression depending on the type of welding process; an appropriate scaling of heat input for 2D finite element simulations and an accurate numerical integration of the weld heat flux expression. Some of the issues associated with the weld path computation are: Options necessary for accurate and convenient specification of the weld path and arc orientation and the calculation of the local coordinate system of the moving source. Some of the issues associated with the weld filler element computation are: techniques available for the treatment of weld fillers in an analysis; boundary conditions for filler elements and multi-pass welds. Speed and ease-of-use related tools that are highlighted include parallel welding computations using the domain decomposition technique, local adaptive meshing schemes, 2D to 3D state variable transfer and global — local structural zooming. This paper describes several algorithms that have been recently developed and implemented in the commercial, non-linear finite element software MSC.Marc. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Selective Laser Melting offers new perspectives in terms of part design and simplification of complex assemblies. However, because such a process is based on the fusion of the material, severe thermo-mechanical conditions arise and are responsible for local plastic deformation, residual stresses and distortion of the manufactured component. Mastering distortion is of major interest in the search for a robust and repeatable industrial process. The lack of experimental knowledge and the high cost associated to a trial and error approach makes it difficult to anticipate distortion relying only on empirical rules. Numerical simulation is therefore an interesting answer both for process understanding thanks to high fidelity models and for process estimation thanks to lighter models. Inherent strain method is part of the latter category of models and proves to be interesting for estimating distortion at a macroscopic level. Experimental calibration of inherent strain induced by the process is a way to get rid of uncertainties associated to a complex thermo-elasto-plastic numerical model. Nevertheless, such an approach requires a reverse analysis in order to identify the inherent strain responsible for the measured elastic springback. This paper proposes a method for a fast reverse identification of inherent strain thanks to the offline generation of a numerical abacus. A model reduction technique called Proper Generalized Decomposition is implemented for the construction of this abacus. [ABSTRACT FROM AUTHOR]

The aim of the work presented in this paper consists of the development of a decision-making support system, based on discrete-event simulation models, of an automobile assembly line which was implemented within an Arena simulation environment and focused at a very specific class of production lines with a four closed-loop network configuration. This layout system reflects one of the most common configurations of automobile assembly and preassembly lines formed by conveyors. The sum of the number of pallets on the intermediate buffers, remains constant, except for the fourth closed-loop, which depends on the four-door car ratio (x) implemented between the door disassembly and assembly stations of the car body. Some governing equations of the four closed-loops are not compatible with the capacities of several intermediate buffers for certain values of variable x. This incompatibility shows how the assembly line cannot operate in practice for x< 0,37 and for x>0,97 in a stationary regime, due to the starvation phenomenon or the failure of supply to the machines on the production line. We have evaluated the impact of the pallet numbers circulating on the first closed-loop on the performance of the production line, translated into the number of cars produced/hour, in order to improve the availability of the entire manufacturing system for any value of x. Until the present date, these facts have not been presented in specialized literature. [ABSTRACT FROM AUTHOR]

This paper deals with the determination of application limits of an already presented method [1] to predict distortion of joined car body assemblies caused by mechanical joining technologies. The investigated method is particularly developed concerning the demands coming from the application in the automotive body production. Parameter studies in simulation and experiment are presented which show the influence of pre-straining and clamping on the joints properties and dimensional accuracy of the assembly. The gained cognitions allow conclusions about the quality of prediction of dimensional accuracy using the proposed simplified model in different joining situations. Finally, the investigated method is applied to a car body assembly. [ABSTRACT FROM AUTHOR]

One important perspective in aeronautics is to produce large, thick or/and complex structural composite parts. The forming stage presents an important role during the whole manufacturing process, especially for LCM processes (Liquid Composites Moulding) or CFRTP (Continuous Fibre Reinforcements and Thermoplastic resin). Numerical simulations corresponding to multi-layered composite forming allow the prediction for a successful process to produce the thick parts, and importantly, the positions of the fibres after forming to be known. This paper details a set of simulation examples carried out by using a semi-discrete shell finite element made up of unit woven cells. The internal virtual work is applied on all woven cells of the element taking into account tensions, in-plane shear and bending effects. As one key problem, the contact behaviours of tool/ply and ply/ply are described in the numerical model. The simulation results not only improve our understanding of the multi-layered composite forming process but also point out the importance of the fibre orientation and inter-ply friction during formability. [ABSTRACT FROM AUTHOR]

With the booming in the manufacturing sector of shoe, garments and toy, etc. in pearl region, training the usage of various facilities and design the facility layout become crucial for the success of industry companies. There is evidence that the use of virtual training may provide benefits in improving the effect of learning and reducing risk in the physical work environment. This paper proposed an advanced web-based training environment that could demonstrate the usage of a CNC machine in terms of working condition and parameters selection. The developed virtual environment could provide training at junior level and advanced level. Junior level training is to explain machining knowledge including safety factors, machine parameters (ex. material, speed, feed rate). Advanced level training enables interactive programming of NG coding and effect simulation. Operation sequence was used to assist the user to choose the appropriate machining condition. Several case studies were also carried out with animation of milling and turning operations. [ABSTRACT FROM AUTHOR]

Since late 1990s, GM Manufacturing Engineering — Die Center has been developing and implementing tube hydroforming simulation technology to GM hydroforming operations. Through successful development and implementation of hydroforming simulation technology, the efficiency and quality of die engineering, tryout, and production have been dramatically improved. This paper presents the critical issues in hydroforming, and the applications of tube hydroforming simulations in the areas of product development, die development, springback and compensation and trouble shooting in tube hydrofoming production. Finally, the latest developments in sheet hydroforming and simulation technology will be discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Permanently increasing complexity of products and their manufacturing processes combined with a shorter “time-to-market” leads to more and more use of simulation and optimization software systems for product design. Finding a “good” design of a product implies the solution of computationally expensive optimization problems based on the results of simulation. Due to the computational load caused by the solution of these problems, the requirements on the Information&Telecommunication (IT) infrastructure of an enterprise or research facility are shifting from stand-alone resources towards the integration of software and hardware resources in a distributed environment for high-performance computing. Resources can either comprise software systems, hardware systems, or communication networks. An appropriate IT-infrastructure must provide the means to integrate all these resources and enable their use even across a network to cope with requirements from geographically distributed scenarios, e.g. in computational engineering and/or collaborative engineering. Integrating expert’s knowledge into the optimization process is inevitable in order to reduce the complexity caused by the number of design variables and the high dimensionality of the design space. Hence, utilization of knowledge-based systems must be supported by providing data management facilities as a basis for knowledge extraction from product data. In this paper, the focus is put on a distributed problem solving environment (PSE) capable of providing access to a variety of necessary resources and services. A distributed approach integrating simulation and optimization on a network of workstations and cluster systems is presented. For geometry generation the CAD-system CATIA is used which is coupled with the FEM-simulation system INDEED for simulation of sheet-metal forming processes and the problem solving environment OpTiX for distributed optimization. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The paper deals with problems related to full/macro scale simulations of industrial forming processes. Large-scale numerical simulations and virtual modeling are replacing prototypes in order to reduce costs and time. This requires accurate and reliable predictions. To satisfy these requirements, sophisticated material models including micro-structural phenomena as phase transitions, aging, and recrystallization have to be considered on macro scale level simulation. Solution strategies are discussed and some examples are given of complex thermo- mechanically coupled forming simulations. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Annual performance simulations provide a valuable tool for analysing the viability and overall impact of different concentrating solar power (CSP) component and system designs. However, existing tools work best with conventional systems and are difficult or impossible to adapt when novel components, configurations and operating strategies are of interest. SolarTherm is a new open source simulation tool that fulfils this need for the solar community. It includes a simulation framework and a library of flexible CSP components and control strategies that can be adapted or replaced with new designs to meet the special needs of end users. This paper provides an introduction to SolarTherm and a comparison of models for an energy-based trough system and a physical tower system to those in the well-established and widely-used simulator SAM. Differences were found in some components where the inner workings of SAM are undocumented or not well understood, while the other parts show strong agreement. These results help to validate the fundamentals of SolarTherm and demonstrate that, while at an early stage of development, it is already a useful tool for performing annual simulations. [ABSTRACT FROM AUTHOR]

This paper presents three projects of Faurecia in the domain of composite part forming and an evaluation of current forming simulation approaches regarding an application in the automotive industry. Via the latter the most performant group of currently available simulation approaches is identified. Their main drawback is however a high computational effort and further research should be done in order to accelerate them. Hereafter recommendations for an ideal forming simulation approach are identified by presenting three projects of Faurecia in the domain of composite part forming. [ABSTRACT FROM AUTHOR]

The concept of Probability of Detection (POD) is generally used to quantitatively assess performances and reliability of NDT operations for in-service operations related to damage tolerant designs. Application of the POD approach as a metric for manufacturing NDT assessment would also be relevant but the very expensive cost of such campaigns generally prevents us from doing so. However the increase in NDT simulation capability and maturity opens the field for POD demonstrations for manufacturing NDT with the help of simulation. This paper presents the example of an automated phased array ultrasonic testing procedure of Electron Beam Welding on rotative parts, as part of the PICASSO European project. POD is calculated by using the uncertainty propagation approach in CIVA. The peculiarity of uncertainties in automated NDT compared to in-service manual operations is discussed and raises questions on appropriate statistics to be used for this kind of data. Alternative estimation techniques like Box-Cox transform or quantile regression are proposed and evaluated. [ABSTRACT FROM AUTHOR]

In this paper the applications, detailed in previous works, of ultrasonic transducers with the addition of axicon lenses are extended. Axicon lenses were manufactured to generate an angular refracted beam in order to study defectology in welds and other components. To achieve greater depth of focus while maintaining a relationship between focus depth and near field (F/N) less than 0.4, larger diameter transducers were used. Furthermore, its effect on the focus diameter (dF) was also analyzed. For different combinations of lens-transducer, diagrams of axial and transverse sound pressure distribution were obtained. At last, several practical applications are shown where it is possible to exploit the advantages that these transducers offer; for example: sizing of shallow cracks, high resolution corrosion mapping simulation, etc. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology for the evaluation of the performance of multistage multiproduct production lines, based on discrete-event simulation models, and developed in an Arena simulation environment. Its purpose is that of analysing blockage and starvation phenomena on a complex production line so as to assist in the decision-making process, since it allows for a greater understanding of the functioning of the production line. This is undertaken through the variation of different parameters, thus contributing to a better specification, characterization and definition of the most efficient planning and control system to be implemented in multistage multiproduct manufacturing processes. The methodology was validated by performing different simulation experiments and will be applied to a multistage multiproduct production line, based on a real case, with a closed-loop network configuration of machines and intermediate buffers consisting of conveyors, which is very common in the automobile sector. There are, in fact, very few studies undertaken which use simulation as a support tool in the decision-making process in the context of networks of closed-loop production lines. [ABSTRACT FROM AUTHOR]

Hemming is a forming operation used in the automotive industry to join inner and outer components during the assembly of closures. These are typically opening parts of the body-in-white with additional requirements to their visual appearance. A suitable production concept of hemming operation which satisfies quality, capacity and cost requirements is determined during hemming planning activities. A digital tool to facilitate these activities and minimize the amount of trial and error iterations in try-out phase is presented in this paper. This tool can be used to define process plan, active tool surfaces and suitable process parameters for both die hemming and roll hemming operations. In case of early feasibility studies, when the die layout of the drawing operation is still not available, 3D part geometry is used directly to develop the concept of hemming process. Advanced validation studies, aimed at process optimization and controlling defects associated with hemming, can be based on complete simulation of all forming operations. Validation and analysis of developed concepts of hemming operation is done using the standard AutoForm-Incremental solver. Submesh strategy and special algorithm for contact description between inner and outer parts were implemented to ensure that accurate simulation results can be obtained within reasonable calculation time. Performance of the new software tool for hemming planning and accuracy of simulation results are demonstrated using several simple benchmarks and a real industrial part. It is shown that the new software tool can help to secure the efficient production launch by providing adequate support in try-out phase. [ABSTRACT FROM AUTHOR]

This paper presents CIMLIB with its two main characteristics: an Object Oriented Program and a fully parallel code. CIMLIB aims at providing a set of components that can be organized to build numerical simulation of a certain process. We describe two components: one treats the complex task of parallel remeshing, the other puts the focus on the Finite Element modeling. In a second part, we present some parallel performances and an example of a very large simulation (over a mesh of 25 millions nodes) that begins with the mesh generation and ends up writing results files, all done using 88 processors. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

This work focuses on the solution of thermal models usually encountered in composite plates welding processes that involve a certain number of numerical difficulties related to: (i) the very fine mesh required due to the small domain thickness with respect to the other characteristic dimensions as well as to the presence of a heat source moving on the domain surface; (ii) the long simulation times induced by the small thermal conductivity of polymers, the important thermal solicitations as well as to the movement of the heat source; and (iii) the necessity to define a homogenized thermal conductivity which can vary significantly from one point to other in the domain. In this paper we explore the applicability of a novel high resolution strategy abe to solve fast and accurately thermal models involving thousands of millions degrees of freedom. This technique opens new perspectives in computational mechanics, and more specifically in material homogenization. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Drawing process is used in manufacturing thin-walled tubes, while reducing progressively their wall thickness and their inner and outer diameters. In this paper a stainless steel 316LVM and a cobalt alloy L605 are studied with two drawing processes, hollow sinking and plug drawing. This study gets into different issues including elastoplastic behaviour, contacts, friction and numerical convergence. Experimental drawings are realized on a testing bench where forces and dimensional data are recorded. In a first approach, tensile tests lead up to apply an elastoplastic constitutive equation with an isotropic hardening law. In simulations, an axisymetric steady-state model, with numeric stabilization if needed, is used. Numerical results are compared with experimental results. Finally, in spite of some defaults, this study shows that finite element modelling is able to foresee accurately the behaviour of a tube during a drawing process. A better understanding and modelling of the mechanical behaviour of materials will improve the FEM simulation results. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Asymmetric incremental sheet forming (AISF) is a relatively new manufacturing process for the production of low volumes of sheet metal parts. Forming is accomplished by the CNC controlled movements of a simple ball-headed tool that follows a 3D trajectory to gradually shape a sheet metal blank. The local plastic deformation under the tool leads to a number of challenges for the Finite Element Modeling. Previous work indicates that implicit finite element methods are at present not efficient enough to allow for the simulation of AISF for industrially relevant parts, mostly due to the fact that the moving contact requires a very small time step. Explicit Finite Element methods can be speeded up by means of mass or load scaling to enable the simulation of large scale sheet metal forming problems, even for AISF. However, it is well known that the methods used to speed up the FE calculations can entail poor results when dynamic effects start to dominate the solution. Typically, the ratio of kinetic to internal energy is used as an assessment of the influence of dynamical effects. It has already been shown in the past that this global criterion can easily be violated locally for a patch of elements of the finite element mesh. This is particularly important for AISF with its highly localised loading and complex tool kinematics. The present paper details an investigation of dynamical effects in explicit Finite Element analysis of AISF. The interplay of mass or time scaling scheme and the smoothness of the tool trajectory is analysed with respect to the resulting errors. Models for tool path generation will be presented allowing for a generation of tool trajectories with predefined maximum speed and acceleration. Based on this, a strategy for error control is proposed which helps reduce the time for setting up reliable explicit finite element models for AISF. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In the present paper, developments in numerical simulation of the hydroforming process of tubular components, tailor-welded before forming, are shown. Both technologies, tailor-welded joining operations and hydroforming processes, are well known in industry, although being usually used separately. Tailor-welded joining operations are usually encountered in plain sheets, subsequently formed by stamping. Tube hydroforming processing, on the other hand, is frequently associated to parts consisting of uniform thickness, material properties and dimensions. Proposing the study and numerical simulation of the joined manufacture process of hydroforming over tailor-welded tubes, the analysis focus on the influence of process parameters, such as the position of the weld-line and initial thickness values, in the overall process, and accounting for distinct thickness values. Particular attention is posed on the relation of imposed displacement vs. imposed hydraulic pressure into the tube to be formed. Another point of practical interest is the numerical simulation and prediction of the weld-line movement, after forming. The Finite Element Method is employed with innovative solid elements well suited for incompressibility applications, included by the authors into the commercial program ABAQUS as user-elements. The obtained results can lead to a better understanding of the process of hydroforming of tailor-welded tubular parts, with dissimilar thickness. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Numerical simulation has become a powerful tool that enables to save costs and time in the design and manufacturing of forged parts for aircraft engines. A complete simulation “package” based on the software code Forge® is used at Snecma to predict the properties of such parts and optimize the manufacturing processes. In order to have a good prediction of the metallurgical and mechanical properties, the simulation of the whole forging process is needed. Until now ring rolling simulation tools have been developed but they still need to be improved. Moreover we have to evaluate these tools before bringing them into production. The aim of this paper is to present the work being done at Snecma on ring rolling simulation. An overview of the complete simulation “package” will first be given. Some tests performed with the ring rolling simulation module in Forge® will be presented, including the comparison between simulation results and real parts. The application to an Inconel® 718 disk will be discussed more into details. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The need for reduction of weight is an important issue in sheet metal forming industry. The hydroforming process has become an effective manufacturing process, as it can be adapted for the manufacturing of complex structural components with high structural stiffness. The process parameters and material properties are important factors that influence the quality of final product. In this paper, an optimized window of process parameters is obtained for successful sheet hydroforming of Oil tank. The simulation of hydroforming process is performed by using a Finite Element Method based Commercial code. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper briefly describes a rotation-free three-node triangular shell elements enhanced formulation and some industrial processes applications where the robustness and accuracy of the element behaviour have been validated. The enhanced formulation is an extension of the rotation free lamina elements (BST, EBST), used for the analysis of smooth surfaces, to the general study of complex branched surfaces behaviour (profiles). © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Forging is a highly complex non-linear process that is vulnerable to various uncertainties, such as variations in billet geometry, die temperature, material properties, workpiece and forging equipment positional errors and process parameters. A combination of these uncertainties could induce heavy manufacturing losses through premature die failure, final part geometric distortion and production risk. Identifying the sources of uncertainties, quantifying and controlling them will reduce risk in the manufacturing environment, which will minimize the overall cost of production. In this paper, various uncertainties that affect forging tool life and preform design are identified, and their cumulative effect on the forging process is evaluated. Since the forging process simulation is computationally intensive, the response surface approach is used to reduce time by establishing a relationship between the system performance and the critical process design parameters. Variability in system performance due to randomness in the parameters is computed by applying Monte Carlo Simulations (MCS) on generated Response Surface Models (RSM). Finally, a Robust Methodology is developed to optimize forging process parameters and preform shape. The developed method is demonstrated by applying it to an axisymmetric H-cross section disk forging to improve the product quality and robustness. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The production process of cement raw material is a large delay, large inertia link; ordinary controlling means by artificial is difficult to get good control effect. In most complex industrial process, predictive control is a good controlling means. In this paper, the modeling method of subspace model identification is used to handle the data gathered from production field. Finally, we obtain a linear discrete model, and then the model is used to design simulation controller. The simulation results show that the control effect is good and meets the control requirements of the production site. [ABSTRACT FROM AUTHOR]

In order to complement ISFOC's characterization capabilities, a Helios 3198 CPV Solar Simulator was installed in summer 2010. This Solar Simulator, based on a parabolic mirror and a high-intensity, small area Xenon flash lamp was developed by the Instituto de Energía Solar in Madrid [1] and is manufactured and distributed by Soldaduras Avanzadas [2]. This simulator is used not only for R&D purposes, but as a quality control tool for incoming modules that are to be installed in ISFOC's CPV plants. In this paper we will discuss the results of recent measurements of close to 5000 modules, the entire production of modules corresponding to a small CPV power plant (200 kWp). We scrutinize the resultant data for signs of drift in the measurements, and analyze the light quality before and after, to check for changes in spectrum or spatial uniformity. [ABSTRACT FROM AUTHOR]

Human interaction within designed processes is a really important factor in how efficiently any process will operate. How a human will function in relation to a process is not easy to predict. All the ergonomic considerations traditionally have been evaluated outside of the 3D product design. Nowadays technologies of 3D process design and simulation tools give us this opportunity from the earliest stages of the design process. Also they can be used to improve current process in order to increase human comfort, productivity and safety. This work shows a methodology using 3D design and simulation tools to improve industrial and service process. This methodology has as an objective the detection, evaluation, control of work-related musculoskeletal disorders (WMSDs). [ABSTRACT FROM AUTHOR]

The aircraft sheet metal part is the important component of aircraft structures and the rubber forming is one of the main forming method for aircraft sheet metal part, the prediction of initial blank sheet shape is a difficult problem for rubber forming. A fast prediction method for initial blank outline of rubber forming based on one-step inverse forming is proposed. Firstly, the designed sheet metal part is treated as the final configuration. Then the quick reverse simulation is carried out to obtain the initial blank outline by the one-step inverse analysis. Finally, the outline from the above method is applied into real rubber forming manufacture. The experimental results are well demonstrated that this method is an effective way to predict the initial blank shape for rubber forming process. [ABSTRACT FROM AUTHOR]

The dynamic behavior of a discrete event dynamic system can be significantly affected for some uncertain changes in its decision parameters. So, parameter sensitivity analysis would be a useful way in studying the effects of these changes on the system performance. In the past, the sensitivity analysis approaches are frequently based on simulation models. In recent years, formal methods based on stochastic process including Markov process are proposed in the literature. In this paper, we are interested in the parameter sensitivity analysis of discrete event dynamic systems by using stochastic Petri nets models as a tool for modelling and performance evaluation. A sensitivity analysis approach based on stochastic Petri nets, called PSA-SPN method, will be proposed with an application to a production line system. [ABSTRACT FROM AUTHOR]

Miniature pulse tube coolers operating at 100Hz have been designed and manufactured. The regenerator is designed by REGEN 3.2, and the inertance tube is simulated by DeltaE. An in-line prototype is manufactured according to the theoretical design parameters initially. On that basis, a coaxial cooler is developed and with double inlet it gains higher cooling performance. [ABSTRACT FROM AUTHOR]

Fixed partial dentures can be fabricated by means of different materials and with different manufacturing processes. In order to establish possible differences among them, their behaviour, as fatigue life or cement shear bond strength, have to be evaluated. This article presents a modular, economic and robust device to evaluate fixed partial dentures and dental crowns. A base to support the fixed partial dentures and a device to simulate masticatory loads have been developed. The device has got a simple design. It is based on a pneumatic piston, with a pressure regulator to control masticatory loads. On a first stage, only vertical forces have been taking into account. However, the device will allow simulating tangential masticatory loads on the other axis, studying the behaviour of the fixed partial dentures submerged in a solution similar to saliva, changing masticatory load application, etc. with little modifications. [ABSTRACT FROM AUTHOR]

Press hardening is a well-established production process in the automotive industry today. The actual trend of this process technology points towards the manufacturing of parts with tailored properties. Since the knowledge of the mechanical properties of a structural part after forming and quenching is essential for the evaluation of for example the crash performance, an accurate as possible virtual assessment of the production process is more than ever necessary. In order to achieve this, the definition of reliable input parameters and boundary conditions for the thermo-mechanically coupled simulation of the process steps is required. One of the most important input parameters, especially regarding the final properties of the quenched material, is the contact heat transfer coefficient (IHTC). The CHTC depends on the effective pressure or the gap distance between part and tool. The CHTC at different contact pressures and gap distances is determined through inverse parameter identification. Furthermore a simulation strategy for the subsequent steps of the press hardening process as well as adequate modeling approaches for part and tools are discussed. For the prediction of the yield curves of the material after press hardening a phenomenological model is presented. This model requires the knowledge of the microstructure within the part. By post processing the nodal temperature history with a CCT diagram the quantitative distribution of the phase fractions martensite, bainite, ferrite and pearlite after press hardening is determined. The model itself is based on a Hockett-Sherby approach with the Hockett-Sherby parameters being defined in function of the phase fractions and a characteristic cooling rate. [ABSTRACT FROM AUTHOR]

Cold formed micro parts with dimensions <1 mm show in some aspects characteristics due to scaling effects that can be positively used in process chains. Whereas aspect ratios in upsetting processes are limited to l0/d0<2 in the macro scale, a laser induced free-forming process generates droplet shaped pre-forms for consecutive calibrating processes, i.e. micro rotary swaging. Scale effects on establishing and shortening of process chains like free-form heading/rotary swaging/heat treatment are discussed. On the other hand a geometric scale-up approach in the macro range is described to overcome the specific handling problems of miniature parts. This is achieved by leaving the parts in a physical linkage during the processing steps. An effective application of linked micro parts requires intensive modeling and simulation work. [ABSTRACT FROM AUTHOR]

The shear deformation and the evolution of the fibre volume fraction of carbon braided reinforcement are studied during the performing step of the RTM process. The determination of these quantities is necessary for their influence on the permeability component for the simulation of the resin injection step. During the performing the complex preform is studied at several scale with an analytical model based on fishnet approach. Numerical results in terms of shear angle, position of the reinforcement, fibre volume fraction, are compared to quantities extract from tomographies realized on composite piece after the resin injection. The model can optimize specific parameters of the braid reinforcement used for this application. [ABSTRACT FROM AUTHOR]

Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

For effective manufacturing of a doubly curved sheet metal, a novel sheet metal forming process is proposed. The suggested process uses a Line Array Roll Set (LARS) composed of a pair of upper and lower roll assemblies in a symmetric manner. The process offers flexibility as compared with the conventional manufacturing processes, because it does not require any complex-shaped die and loss of material by blank-holding is minimized. LARS allows flexibility of the incremental forming process and adopts the principle of bending deformation, resulting in a slight deformation in thickness. Rolls composed of line array roll sets are divided into a driving roll row and two idle roll rows. The arrayed rolls in the central lines of the upper and lower roll assemblies are motor-driven so that they deform and transfer the sheet metal using friction between the rolls and the sheet metal. The remaining rolls are idle rolls, generating bending deformation with driving rolls. Furthermore, all the rolls are movable in any direction so that they are adaptable to any size or shape of the desired three-dimensional configuration. In the process, the sheet is deformed incrementally as deformation proceeds simultaneously in rolling and transverse directions step by step. Consequently, it can be applied to the fabrication of doubly curved ship hull plates by undergoing several passes. In this work, FEM simulations are carried out for verification of the proposed incremental forming system using the chosen design parameters. Based on the results of the simulation, the relationship between the roll set configuration and the curvature of a sheet metal is determined. The process information such as the forming loads and torques acting on every roll is analyzed as important data for the design and development of the manufacturing system. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The solution of forming processes requires reliable and efficient finite element methods to model the various complex physical phenomena encountered. The objective in this presentation is to focus on the current state of finite element methods with respect to reliability and efficiency in modeling forming processes. The finite element procedures pertain to the simulation of sheet metal forming, bulk forming, extrusion and drawing, rolling, welding, cutting processes, etc. It is emphasized that the appropriate finite element methods for a specific problem should be used, and that indeed procedures are available which are effective in many situations. The presentation briefly considers the state of modeling of solids, shell structures, contact conditions, friction, inelastic material response in large strains, thermo-mechanical coupling and fluid-solid interactions, as encountered in forming process simulations. The solutions of the governing finite element models are obtained using sparse direct or iterative solvers. The oral presentation will include the results of various example simulations. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Compression molding has become a viable manufacturing process for medium to high volume production of aspherical glass lenses. The lack of fundamental understanding of the process and other technical issues ranging from thermal shrinkage to mold coating wear and long molding cycles have made this process unsuitable for industrial applications. In this research, the various stages of the lens molding process have been modeled to understand the effect of different molding parameters to the final lens quality (geometry). 2-D axisymmetric simulations of the glass molding process have been performed using a commercial Finite Element Method (FEM) code. Glass has been modeled as a Newtonian fluid and temperature dependent viscosity and the heat transfer at the glass mold interface have also been taken into consideration. One of the main objectives of this research was to include the effect of viscoelasticity (time dependent response of glass to mechanical load), into the simulation model. A limited number of experiments were also performed and a comparison of the predicted results has been made with the experimental data. Although the predicted results seem to be in qualitative agreement with the experimental data, further research needs to be performed on viscoelasticity, structural relaxation (time dependent response of glass to change in temperature), and non-Newtonian behavior of glass at high stress levels, in order to make FEM a more effective tool for process analysis and optimization. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The hot embossing process has been known as one of major nano replication techniques. This is due to its simple process, low cost, high replication fidelity and relatively high throughput. As the initial step of quantitating the hot embossing process, simple parametric studies for the embossing time have been carried out using high-resolution masters which patterned by DRIE process and laser machining. Under different embossing times, the viscous flow of thin PMMA films into micro cavities under the compression force has been investigated. Also, the viscous flow during the embossing process was simulated by the continuum based FDM analysis considering micro/nano effect, such as surface tension and contact angle. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We performed a program simulation for design and development of highly efficient organic photovoltaic cells. And the cells were manufactured under the optimum conditions obtained from the simulation. From the device structure of ITO/PEDOT:PSS/CuPc/C60/BCP/LiF/Al manufactured under the optimum conditions obtained from the simulation, it was found that the power conversion efficiency was 0.41 %. We have confirmed that the power conversion efficiency was increased by 3.4 times compared to that of reference cell (ITO/CuPc/C60/BCP/Al). [ABSTRACT FROM AUTHOR]