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Resin transfer molding (RTM) process is a major molding process in the manufacture of resin-based composites, and the simulation of this process can play a key role in the process of optimization for the design of RTM parts. This paper independently developed a three-dimensional non-isothermal RTM simulation model based on the control volume/ finite element method (CV/FEM) on the basis of two-dimensional isothermal RTM program. Based on the Darcy equation, the continuity equation, the energy conservation equation, the curing reaction equation and multiple rheological curing models, the simulation model adopts semi-discrete method and three convergence criteria to effectively solve the problems of mold preheating and resin non-isothermal in the non-isothermal RTM simulation process. For the simulation problems such as viscosity changing and curing heat release during the filling process, the simulation function has reached the level of similar international products. After the application verifications of the flat plate test piece and casing simulation, this simulation model can simulate filling time, velocity and pressure of RTM process that is the same as the products in the world. This simulation model basically has the ability of simulation for the actual complex structure parts. [ABSTRACT FROM AUTHOR]

In spite of the development of automated tolerance inspection systems for manufactured parts over the years, there are still processes that inevitably require manual intervention making full automation impossible in most cases; in particular when dealing with deformable parts. In most current industrial inspection systems, a deformable part under inspection must first be mechanically constrained on a rigid support or jig so as to be able to compare it with its nominal shape. This paper presents a new system to perform real-time surface inspection of deformable parts that does not require fixturing. Instead, the proposed system applies virtual forces to the part's CAD model as if the part was installed in the fixturing device. Normally, a precise finite element method (FEM) simulation should be used to approximate the deformation that appends when the part is installed in the device. Even with a fast parallel computer, FEM is far from being real-time and cannot be used for on-line inspection. In the proposed system, a radial basis function approximation of the FEM simulation is trained off-line and used to speed-up the simulation by an order of magnitude. Experimental evaluation of the proposed system is presented for three plastic parts. Using the proposed scheme, an approximation of 0.25 mm compared with the real deformation was obtained. In this paper, statistical results are presented such as the average deviation, standard deviation, and processing time between the approximations obtained with the proposed method and with the finite element method applied to the full CAD model. [ABSTRACT FROM AUTHOR]

The manufacturing of components requires several manufacturing process steps that are performed in a sequence, during which the raw material is progressively converted into finished parts. The aim with simulation of manufacturing sequences is to replicate the aggregate effects of the process steps on key features of the finished product and manufacturing features. With the support of a successful simulation methodology, it will thereby be possible for process planners to evaluate virtually and select process steps to be included in the manufacturing sequence and to optimize process parameters. The motivation to implement sequential simulation in industry is therefore strong and will reduce time and cost in process planning. The modelling and simulation of complete manufacturing sequences is, however, a challenge which may lead to unrealistic and time-consuming modelling efforts and extensive computational requirements. This is due to the often complex material transformations through several consecutive process steps. In order to adapt sequential simulation into an industrial environment, simplifications are therefore necessary. This paper proposes a method for simplified metamodelling of manufacturing sequences, using upstream selection of process steps and definition of interconnected models. The method is presented as an algorithm and will improve the efficiency in the modelling of manufacturing sequences. The usability of the algorithm is demonstrated with two industrial cases: a bevel gear pinion and a steering arm. [ABSTRACT FROM AUTHOR]

The aim of our study was to verify if rule-based reasoning systems could be successfully applied for integration of different models and tools which are used for solving complex decision problems in technological design. Engineering problems are unique and differ from typical problems in the domain of management. To solve those problems, an iterative search of the most suitable solutions must be carried out. This puts a pressure on researchers to utilize optimization techniques in connection with simulation methods. Our research is focused on the usage of rule-based reasoning systems for solving simple decision problems, and their integration with highly-specialized tools. This research has been conducted at one of metal foundries, within the scope of supporting technological decisions. A dedicated platform was used in the research, which is tailored for such applications, i.e., Business and Technological Rules Management System REBIT. REBIT system has been developed at the Faculty of Management at the AGH University of Science and Technology in Cracow. In this paper, we prove that the rule-based approach could provide means to integrate all stages of technological design. This kind of approach has been successfully applied in the Business Rules Management Systems. [ABSTRACT FROM AUTHOR]

Due to the compliance and geometrical defects of composite parts, gaps exist between assembly components after the preassembly. Assembly requirements impose to fill these gaps to eliminate any unexpected internal stresses. Although it is identified as a problematic and expensive nonadded value stage, a gap measurement is still needed. This paper develops a numerical process for gap prediction before the assembly step. After the assembly components are scanned in a specified configuration, finite element meshes are created using the scanned data and the shape variations of each component caused by constraints and forces in different configurations are evaluated by finite element analysis. Assembly gaps are finally assessed by assembling the simulated preassembly shapes of all components. The feasibility of the proposed method is proved by an experiment. [ABSTRACT FROM AUTHOR]

The object of the paper is constituted by the simulation of the operation regimes of an electric transformer, using specialised simulation software, in order to determine the electromagnetic strains to which welding transformers are subjected to in the case of the faulty operation. The monitoring processes of the modern welding equipment impose the reduction of the risk of their breakdown, grace to the collection and processing of detailed information about the condition of the transformers with the help of specialised modelling software with finite element. [ABSTRACT FROM AUTHOR]

Individualized production, which is a major goal of many high-wage countries, describes a production process in which all elements of a production system are designed in such a way that they enable a high level of product variety at mass production costs. This paper demonstrates recent advances in the individualized production with die-based manufacturing processes, namely high-pressure die casting and plastics profile extrusion. Within these application areas, the chosen approach aiming at individualized production is based on the use of numerical die and process design. The design procedure relies on numerical process simulations based on a nonlinear optimization library and a spline-based geometry kernel. All components interact automatically without requiring user interaction; thus, a completely independent optimization cycle can be achieved. The numerical optimization helps to reduce-or even eliminate-the so far very characteristic manual reworking steps of an original die or process design. These reworking steps are a major cost factor when it comes to individual production. Their abolishment through the presented numerical approaches therefore represents a large step towards the concept of individualized production. [ABSTRACT FROM AUTHOR]

Although high strengths up to 1,500 MPa can be obtained by means of hot stamping, the strength and uniformity of components cannot be guaranteed during mass production if the cooling channel is not properly designed. In this paper, we propose a method for designing the cooling channel by means of the energy balance principle and arrangement methods such as the triangular method, tool split, and the connection rule for 2D sections to improve the strength and uniformity of hot stamped components. Two separate approaches for designing the cooling channel are suggested. One is to reduce facility and maintenance costs, and the other is to reduce the cooling cycle time, which critically affects productivity. These approaches were applied to hot stamping tools for manufacturing a roof side that is used as part of the structure of an automobile. Cooling performance and cooling uniformity of the designed cooling channel were verified with finite element simulation. Finally, hot stamping tools for manufacturing a roof side were designed to reduce cooling cycle time and were then manufactured to verify the proposed design methods. A roof side was manufactured by means of the hot stamping tools with the designed cooling channel, and the strength and the uniformity of the component were evaluated by means of a tensile test, observation of the microstructure, and measurement of the micro-Vickers hardness. [ABSTRACT FROM AUTHOR]

Abstract: Manufacturing of advanced components like aeroengine parts is performed in a global network. Different manufacturers deliver individual components to the engine and even different manufacturing steps for a given component may be performed at different companies. Furthermore, quality is of utmost importance in this context. Simulations are increasingly used to assure the latter. The current paper describes the simulation of a chain of manufacturing processes for an aeroengine component. Different partners have performed the simulations of the different steps using a variety of finite element codes. The results are discussed in the paper and particularly the lessons learned regarding the modelling process. [Copyright &y& Elsevier]

Selective Laser Melting (SLM) is actually the most attractive technique in an Additive Manufacturing (AM) technology because of the possibility to build layer by layer up nearly full density metallic components without needing for post-processing. One of the main problems in SLM processes is represented by the thermal distortion of the model during forming; the part tends to be deformed and cracked due to the thermal stress. Therefore, it is important to know the effect of the process parameters on the molten zone and consequently on the density of the consolidated material. Great advantage can be obtained from the prediction of temperature evolution and distribution. The aim of this study is to evaluate the influence of the process parameters on the temperature evolution in a 3D model. The developed code evaluates the distribution and evolution of the temperatures in the SLM process and simulates the powder-liquid-solid change by means of a check of the nodes temperature. (Received in June 2010, accepted in June 2011. This paper was with the authors 1 month for 1 revision.) [ABSTRACT FROM AUTHOR]

This paper compares finite element model (FEM) simulations with experimental and analytical findings concerning precision radial turning of AISI D2 steel. FEM machining simulation employs a Lagrangian finite element-based machining model applied to predict cutting and thrust forces, cutting temperature and plastic strain distribution. The results show that the difference between the experimental and simulated cutting force is near 20%, irrespectively of the friction coefficient used in the simulation work (approximately 19.8% for a friction of 0.25% and 18.4% for the Coulomb approach). Concerning the thrust force, differences of about 22.4% when using a friction coefficient of μ = 0.25 and about 56.9% when using the Coulomb friction coefficient ( μ = 0.378) were found. The maximum cutting temperature obtained using the analytical model is 494.07°C and the difference between experimentation and simulation methods is 15.2% when using a friction coefficient of 0.25 and when using the Coulomb friction only 3.1%. Regarding the plastic strain, the differences between analytical calculations and FEM simulations (for the presented friction values) suggest that the finite element method is capable of predictions with reasonable precision. [ABSTRACT FROM AUTHOR]

In this paper, the machining process to produce the right surface profile in machining low-rigidity parts is studied by considering moving dynamic cutting forces that statically and dynamically excite the tool and part reducing the validity of these packages’ output and leading to additional surface errors. The proposed approach is based on producing a simulation environment integrating a data model, an analytical force prediction model, a material removal model and an FE analysis commercial software package. This reported result focuses on the development of the simulation environment and the data model. The integrated environment provides a platform by which FE analysis commercial packages, ABAQUS, can exchange data with the proposed data model, force model and material removal model, to deliver new functionality for machining process simulation where there is force-induced part deflection. The data model includes complete mesh and analysis information for predicting part deflection and enables iterative data updating for multi-step simulation. The proposed simulation methodology has been experimentally validated. [ABSTRACT FROM AUTHOR]

The simulation of a manufacturing process chain with the finite element method requires the selection of an appropriate finite element solver, element type and mesh density for each process of the chain. When the simulation results of one step are needed in a subsequent one, they have to be interpolated and transferred to another model. This paper presents an in-core grid index that can be created on a mesh represented by a list of nodes/elements. Finite element data can thus be transferred across different models in a process chain by mapping nodes or elements in indexed meshes. For each nodal or integration point of the target mesh, the index on the source mesh is searched for a specific node or element satisfying certain conditions, based on the mapping method. The underlying space of an indexed mesh is decomposed into a grid of variable-sized cells. The index allows local searches to be performed in a small subset of the cells, instead of linear searches in the entire mesh which are computationally expensive. This work focuses on the implementation and computational efficiency of indexing, searching and mapping. An experimental evaluation on medium-sized meshes suggests that the combination of index creation and mapping using the index is much faster than mapping through sequential searches. [ABSTRACT FROM AUTHOR]

Abstract: A new rotary forming process used to thicken the rim of a disc-like part was proposed. The paper details the results, design and manufacture of the corresponding apparatus. The center point of a ring roller moves around the axis of a stationary work-piece in a plane spiral locus, like a rounding hula hoop. Thereby, the rim of stationary work-piece is rolled and thickened. A design rule for the rotary thickening process of the disc-like part was proposed, and a formula for calculating the feeding force of the roller was deduced. Both the design rule and the formula were verified by the results of experiment and finite element simulation. The forming and flow law during the thickening process were also illustrated. [Copyright &y& Elsevier]

Abstract: A Finite Element Data Exchange System (FEDES) is developed to transfer and map finite element analysis (FEA) data between different FE solvers and meshes. Six commercial FE codes (ABAQUS, ANSYS, DEFORM, MSC.MARC, MORFEO and VULCAN) are incorporated in FEDES. Four mapping techniques are developed and embedded in FEDES which allow the data mapping between meshes with different element types and densities. The algorithms of the mapping techniques are described and compared for 2D and 3D models. The design and capabilities of FEDES are also described. Results from the data transfer and mapping between different FE simulations are presented and discussed. Two manufacturing chains are simulated using FEDES in this paper. The first manufacturing chain is simulated on a parallelepiped geometry including casting, forging and heat treatment processes. The second manufacturing chain is simulated on an aero-engine vane component including metal deposition, welding, heat treatment, machining and shot-peening processes. The development of FEDES demonstrates an integrated simulation platform for modelling manufacturing chains of processes using different FE solvers and meshes. [Copyright &y& Elsevier]

Abstract: The downscaling of manufacturing processes leads to a rise in new challenges in process design. Amongst these challenges is a decrease in the limiting drawing ratio observed in micro deep drawing of metal foils. Furthermore, fracture occurs at punch force levels well below those predicted by common equations. In this paper it is proposed that these phenomena can be accounted for by non-uniformities in the flow behavior of the material due the large difference between grain sizes. The localized strains before fracture – as recorded by digital image correlation – of stretch formed aluminum foils are presented and the strain evolution is examined. Evidence to verify the hypothesis is gathered by implementing the observed flow non-uniformities into a finite element simulation and comparing the computed results to the experimental ones. [Copyright &y& Elsevier]

Abstract: The folding of thin shells around localized lines occurs in several situations of engineering interest, such as in buckling induced deformation, as the consequence of crash, in industrial processes like metal forming, in the deployment of folded membranes, in packaging related processes. In this paper an interface element, allowing for displacement and rotation discontinuities, to be placed between two adjacent 4-node Mindlin–Reissner shell finite elements, is developed for a computationally effective simulation of this type of localized deformation. The large displacement and rotation kinematics of the interface element is discussed, arriving at a rigid-rotation free element tangent stiffness matrix. An adaptive dynamic relaxation scheme is proposed for the evolutionary analysis of the quasi-static structural response. To test the element formulation, a simple coupled membrane-bending elastoplastic behavior is assumed. The element is used for the simulation of few examples taken from the literature, where the structural response is characterized by the formation of plastic hinges, exhibiting good accuracy and computational effectiveness. [Copyright &y& Elsevier]

The main aim of this paper is to review some different models, from simple to very complicated, for computing the changes in flow stress depending on the deformation conditions. Some of the models can be applied to cold forming and some to hot and warm forming. A finite element analysis (FEA) of the dieless drawing process was undertaken. The FEA simulation was carried out using Forge3, a FEA software, specifically produced for metal forming simulation. An axisymmetrical 3D geometric model of the tooling and billet was constructed for the analysis. The data obtained from the FE model included temperature, equivalent von Mises stress, equivalent strain and material deformation velocity. [ABSTRACT FROM AUTHOR]

For a lot of production areas but particularly for automotive industry spot welding is one of the mostly used welding procedures. Most of these welding spots are arranged in line but this displacement is not always the best choice regarding traction behaviour. There are situations when no physical space is available to line up the welding spots in which case another arrangement should be found. In this paper are presented simulation and test results for spot welded joints under traction stress but for different spot arrangement. This study is based on tests on spot welded joints in which the spots were disposed in different patterns such as: square, parallelogram and rhombus. Based on tests, square arrangement turned out to be the most convenient solution. A better traction resistance for welded joint means less welded spots and means energy saving. [ABSTRACT FROM AUTHOR]

In Finite Element Analysis of the Roll Forming (RF) process of automotive component, there are two methods for numerical simulation. The first one is general analysis, and the second is a specific analysis. The general approach is a deeper investigation but takes a long time for simulation, while the specific approach uses many assumptions for RF, takes less computer time and can analyze many special processes quickly. This paper investigates many RF processes of automotive components by using both methods, in order to identify differences between them as well as build the foundation for using the combination of different methods in analyzing and designing RF process. A realistic application in analyzing and designing is developed and shows the good efficiency in comparison with the previous procedure. [ABSTRACT FROM AUTHOR]

Abstract: During the last few years it has become more and more customary for major industries to use FEM simulations during the product creation process. Most of these metal-forming process simulations are based on elastic plastic behaviour of material and use non-deformable tools. For a correct use of FEM simulations in product development stages, it is very important to determine the accuracy of the simulations. For multi-stage processes, it can be more effective not to simulate the total process but only a few stages of the process, with the last stages usually being the most important ones. To start simulations half way the total process calls for information on the semi-finished product. This information is generated by means of measured values in order to decrease the total modeling time and to increase the accuracy. This paper shows a method developed for handling these problems. The method based on a fully automatic measuring device, including a LECO hardness tester. The results of these measurements were used to verify models, including models based on the transformation behaviour of strain-induced martensite. The examples presented are based on products made of a stainless steel called Nanoflex . [Copyright &y& Elsevier]

Abstract: Multi-point stretch forming (MPSF) is a flexible manufacturing technique to form large sheet panels of mild curvature. The traditional fixed shape-stretching die is replaced by a matrix of punch elements, and the sheet metal are stretch-formed over the multi-point stretching die (MPSD) generated by the punch element matrix. In this paper, extensive numerical simulations of the processes for stretching parabolic cylinder, toroidal saddle and sphere parts were carried out by dynamic explicit finite element analysis. The forming results using multi-point die were compared with those of using traditional die. The use of an elastic cushion to suppress dimpling of the part caused by the discrete punch elements was investigated along with a discussion of its influence on part shape accuracy. The effect of the size of punch element and the shape of MPSD on the shape accuracy of formed parts were analyzed. The results may provide useful guidance on determining MPSF parameters and optimizing MPSF manufacture processes. [Copyright &y& Elsevier]

We present a generalized Lagrangian formulation for analysis of industrial forming processes involving thermally coupled interactions between deformable continua. The governing equations for the deformable bodies are written in a unified manner that holds both for fluids and solids. The success of the formulation lays on a residual-based expression of the mass conservation equation obtained using the finite calculus method that provides the necessary stability for quasi/fully incompressible situations. The governing equations are discretized with the FEM via a mixed formulation using simplicial elements with equal linear interpolation for the velocities, the pressure and the temperature. The merits of the formulation are demonstrated in the solution of 2D and 3D thermally-coupled forming processes using the particle finite element method. [ABSTRACT FROM AUTHOR]

Manufacturing diamond wheels on various bonds is a relatively high-cost process, requiring high labour and high consumption of expensive diamond grains but yielding relatively low productivity. With better knowledge of the various factors involved in the sintering process, the most efficient combinations can be found, leading to higher productivity. Currently, there are no scientifically based recommendations for the choice of the rational combinations of strength, brand of grain, graininess and concentration with the physical-mechanical properties of bonds. The aim of this research is the development of a technique for the theoretical definition of an optimal combination of strength properties of diamond grains and bond to provide maximum retention of diamond grain integrity during the process of diamond wheel manufacture. This is investigated using 3D simulations of the deflected mode of the sintering area of the wheel's diamond-bearing layer. [ABSTRACT FROM AUTHOR]

Variation analysis of assemblies is a strategic task in many industrial applications. Parts manufactured through plastic deformation processes exhibit appreciable shape deviations from the nominal geometry due mainly to spring-back phenomena. When these parts are assembled, initial shape deviations at part level highly influence the final assembly shape. This work focuses on the modeling and simulation of shape errors in order to perform variation analysis of compliant assemblies. The aim is to simulate variational shape of parts according to a small number of control points chosen on the part geometry through a morphing mesh procedure. These points are typically related to measurement or inspection points of manufactured parts. From the mesh model of parts, mesh nodes are moved by applying the morphing procedure. In particular, in order to assure control points belong to the 'perturbed' shape, a linear-constrained approach is adopted. The so-morphed parts are used to accomplish the variational assembly analysis following the classical place, clamp, fasten, and release cycle. In order to achieve statistical results, Monte Carlo simulation is performed: a set of control points driving the perturbed parts is generated at each iteration; these parts are then assembled and results are stored. Numerical results are compared with ones coming from commercial software that uses a linear approach based on the sensitivity matrix. [ABSTRACT FROM AUTHOR]

Bursting is an irrecoverable failure mode in tube hydroforming, in contrast with buckling and wrinkling. To predict bursting failure in the hydroforming processes, Oyane's ductile fracture criterion is introduced and evaluated from the results of stress and strain productions obtained from finite element analysis. The region of fracture initiation and the bursting pressures are predicted and compared with a series of experimental results. It is shown that the material parameters used in the criterion can be obtained from the forming limit diagram. From the simulation results of tube bulging, the prediction of the bursting failure based on the ductile fracture criterion was demonstrated to be reasonable. This approach can be extended to a wide range of practical tube hydroforming processes. [ABSTRACT FROM AUTHOR]

In order to accurately predict damage and failure evolution in metal forming processes such as stamping, blanking and bending, a finite element model has been developed which is valid for the numerical description of such processes. Numerical simulation of the damage evolution has been modelled by means of a continuum damage approach. The Lemaitre damage model which takes into account the influence of triaxiality has been implemented using the ABAQUS/Standard code. The model enables damage and fracture initiation to be examined under several different loading conditions and geometry configurations. An example of the L-bending process is given to illustrate the potential applicability of the model. [ABSTRACT FROM AUTHOR]