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The current paper attempts to develop a mathematical model to predict springback of thick sandwich panel made of steel/polyurethane (PUR)/steel in air bending process. Firstly, the behavior laws of sandwich panel components were experimentally obtained. Secondly, numerical simulations of the sandwich panel were conducted in bending process followed by springback for various process parameters. We found that the predicted springback agrees with experiment. Thirdly, three factors with three levels were considered in order to obtain a mathematical model to predict springback by using response surface method (RSM). Punch radius, die opening, and foam thickness are chosen as the main input parameters. The springback is considered as the output response. A relationship between the different factors and the response was obtained, and regression analysis has been done. The obtained results were analyzed with analysis of variance (ANOVA) in order to identify the factors' importance on the response. [ABSTRACT FROM AUTHOR]

The electrical discharge machining (EDM) process is a popular non-traditional machining process, but, although it is widely used in industry, there is still a lack of scientific knowledge about its fundamentals. This paper discusses some aspects of the discharge process at the sight of the results obtained with a previously developed thermal model, which is capable of simulating the superposition of successive discharges which leads to the formation of the 'EDMed' surface. Some process characteristics such as the percentage of discharge energy transferred to the workpiece, plasma channel growth, material removal mechanism, and the influence of convective cooling are discussed in this paper, based on the information provided by the adjustments of two different EDM regimes (corresponding to roughing and finishing operations). Predictions of the extension of the recast layer and the heat-affected layer for both regimes are also addressed, and their comparison with experimental measurements shows a good agreement, which confirms the validity of the modeling tool. [ABSTRACT FROM AUTHOR]

Having first defined the helical angle as the angle between the cutting edge and the axis of rotation of the cutter, this paper then presents design models for producing the cutting edge and groove of a ball-end cutter with concave-arc generator. The relative feed speeds of the grinding wheel in the radial and axial directions during NC machining of the cutter are derived based upon a given speed of rotation. The feed speed of the grinding wheel in the radial direction is modified according to the cross section of the groove that passes through the center of the cutter sphere. The paper presents a method for manufacturing a concave-arc ball-end (CABE) cutter using a 2-axis NC machine. The models that are used to calculate the actual obtained groove and the computer simulation method are also included. To further enhance the accuracy of the mathematical models, a compensatory machining process that eliminates residual profile on the revolving surface is presented. This paper provides a valuable reference for the design and machining of this cutter type. [ABSTRACT FROM AUTHOR]

This paper deals with a discrete simulation optimization method for designing a complex probabilistic discrete event system. The proposed algorithm in this paper searches the effective and reliable alternatives satisfying the target values of the system to be designed through a single run in a relatively short time period. It tries to estimate an auto-regressive model, and construct mean and confidence interval for evaluating correctly the objective function obtained by a small amount of output data. The experimental results using the proposed method are also shown. [ABSTRACT FROM AUTHOR]

Discrete event simulation (DES) has been widely applied to modelling and simulation of computer and engineering systems and is an active field of research that has now evolved from 2D to 3D discrete event simulation. This paper attempts to address several key issues in a successful implementation of DES models based on our own and the previous experiences of others. It describes the common basis, which forms the core for the application of modelling and simulation methodologies that are available to support manufacturing systems analysis, design and performance evaluation. Through a comprehensive literature survey, this paper summarises and compares the most widely used optimisation techniques for simulation of manufacturing systems; an overview of the recent and popular simulation languages and packages available for the modelling and simulation community and the classification of their utility for modelling and simulation of manufacturing systems is also given. Finally, this paper summarises and reports the latest development in the most exciting world wide web (www)-based simulation techniques that represent a future that may completely change the nature and future exploitation of modelling and simulation technology in industry. [ABSTRACT FROM AUTHOR]

The designing of twist drill flutes (as well as that of end mills and of some combined tools) cannot be separated from the way they are manufactured. The aim of this paper is to present an intuitive direct method for modelling, simulation and manufacturing of the drill flutes with different shapes using conical grinding wheels with standardized shapes. The mathematical approach is described, which enables us to determine the flute profile in a section perpendicular to its axis as well as the manufacturing parameters. The grinding wheel has an initial position with respect to the cylindrical work piece, which is described using four parameters (Denavit Hartenberg parameters). We have presented algorithms in pseudocode that produce the flute shape and that compute the optimum parameters of the wheel position in the manufacturing process. Subsequently, a software application based on the aforementioned model is able to create visualizations of the flute shape. The analysis of the flute shape has enabled us to understand the influence of the geometrical parameters and the position of the grinding wheel on the resulting product in the grinding process. The order in which these parameters are to be set is also specified. We have built atlases of maps presenting the influence of the geometrical parameters and the position of the grinding wheel in the grinding process upon the shape of the flute. The validity of the method is proven by the agreement of the computed values with the input and output data produced by experiment. The proposed method allows helical flutes to be generated solely by using cylindrical and conical grinding wheels of standard shapes. [ABSTRACT FROM AUTHOR]

Finite element simulations are being more and more applied when studying the crash-worthiness of vehicles during impact. This paper deals with setting up such a simulation and discusses several ways to simplify and verify a simulated crash. For this purpose, a notch impact-testing machine will be released from a certain angle and crash into a model constructed with three different wall thicknesses. The plastic and elastic deformation is measured in the front of the model and is then used for validation of the simulation. In the end, the simulation was found to be in good agreement with the real crash data. [ABSTRACT FROM AUTHOR]

Material constitutive model is one of the basic scientific fundamentals for simulation accuracy of high-speed cutting (HSC). A high-speed orthogonal cutting method (HS-OCM) based on the shear slip distance, aided by split Hopkinson pressure bar (SHPB) experiments, is proposed in this paper to obtain the shear slip deformation characteristics in the HSC of 6061-T6 aluminum alloy. The Johnson-Cook (JC) model was modified in three ways according to the variation tendencies of the effect curves of strain hardening, strain rate strengthening, and thermal softening, and an improved material constitutive model was obtained. The simulation validations of the obtained material constitutive models were executed. It was found that the modified JC model improves simulation accuracy, i.e., the maximum simulation errors of the cutting force and cutting temperature are 18.5 and 12.2 %, respectively. The HS-OCM avoids the cutting speed limitation (<700 m/min) of the quick-stop test usually used in conventional OCM and the difficulty of predicting tendency inflection points of the inverse identification method employing a finite element simulation model, and allows the experimental measurement of the deformation characteristics of 6061-T6 aluminum alloy in high-speed (2000 m/min) cutting. During HSC of 6061-T6 aluminum alloy, the shear stress, shear strain rate, and deformation temperature in the primary deformation zone increase with increasing cutting speed, whereas the shear strain decreases. [ABSTRACT FROM AUTHOR]

Assembly modeling and simulation are two important activities in product development. The former makes an assembly model by specifying mating constraints between parts. The latter visually simulates the process of forming an assembly model through sequencing and finding paths of parts. In practice applications, the sequence of assembling parts in assembly modeling cannot be directly utilized to facilitate path finding and sequencing in assembly simulation, and specifying mating constraints in assembly modeling and finding/sequencing paths of parts in assembly simulation are usually accomplished manually, which are tedious and error-prone. One responsible reason is that when creating part models, designers know how they will interact with each other, but this information is not stored in part models. To alleviate the problems, this paper introduced the concept of assembly feature pair (AFP) and proposed a framework method to integrate assembly modeling and simulation. An AFP consists of form feature pairs on two parts together with assembly behaviors. Correspondingly, the mating constraints between parts and the information of assembly process can be captured to facilitate assembly modeling and assembly simulation. Based on AFP, the framework method can integrate assembly modeling and simulation from three aspects: (1) AFPs will be embedded into part models at part modeling stage, storing designers' knowledge of how parts will interact with each other, (2) the laborious work of applying mating constraints between parts in assembly modeling will be replaced by instantiating the embedded AFP in part models, and the instantiation sequence of AFPs will be directly used in assembly simulation, and (3) the manual work of planning and sequencing paths of parts in assembly simulation will also be replaced by instantiating the embedded AFP in part models based on the randomized motion planning theory. To demonstrate the theoretical framework, an implementation sample was presented. [ABSTRACT FROM AUTHOR]

Accurate prediction of cutting force plays an important role in simulation and application of orthogonal turn-milling operation. However, the existing cutting force models for this operation are limited to the case with flat-end cutters, which is not enough in practice. The objective of this paper is to extend the simulation of cutting forces in orthogonal turn-milling into the case with round insert cutters. To achieve this goal, the basic kinematic relationship between the tool and the part is discussed firstly in detail. Then, the approaches to determine two vital factors, namely undeformed chip thickness and the tool-part engagement region are presented. With the real swept surface of the cutting edge replaced by the geometry envelop of the tool, the analytical formulation of the undeformed chip thickness is derived. The engagement region is determined by judging the positions of discretized cutting edge elements and the in-process workpiece surface, which is described by the mapped grids. Using the cutting coefficients calibrated through experiments, cutting forces are calculated. Validation experiments under different conditions were conducted on a turn-mill machine tool with rotating cutting force dynamometer used. The results prove that the proposed model is capable of predicting cutting forces accurately both in shape and magnitude. [ABSTRACT FROM AUTHOR]

The development of precision machine tools requires an accurate understanding of the thermal behaviour of the tools. Therefore, by developing highly accurate machine tool thermal behaviour simulations, it can accurately forecast the functional performance of a machine tool at the prototype design stage and provide guidance on its design and performance optimization. To improve the accuracy of the thermal simulation of machine tools, it proposed whole-machine temperature field and thermal deformation modeling and a simulation method for vertical machining centers. Based on the studies of thermal-structure coupling finite-element data flow and its critical conditions, it also proposed design and computational methods for obtaining the heat-source power, when various rotational speeds, the forced convection heat transfer coefficient between a rotating surface and the air, the combined heat transfer coefficient between a stationary surface and the air/environment, and key contact surface thermal resistances were considered. Furthermore, this paper performed finite-element simulation analysis based on the constructed whole-machine thermal model, and the temperature characteristics and heat deformation mechanism/state were obtained. After comparing the simulation and experimental results, it verified the effectiveness of the finite-element simulation model and the relevant methods and confirmed that the simulation accuracy for both the temperature characteristics and the thermal deformation had been improved significantly, with a simulation error less than 10 %. [ABSTRACT FROM AUTHOR]

As a widely used engineering material, optical glass is very difficult to process because of its high hardness and brittleness. The material removal mechanism still needs further investigation. In this paper, a mesh-free simulation method—smooth particle hydrodynamics (SPH)—is introduced and an ultra-precision cutting model for K9 glass is provided. Compared with conventional finite element method, the SPH method can effectively avoid mesh distortion when dealing with large deformation problems such as cutting. Several numerical simulations were carried out to further investigate the critical value of transition. Simulation results indicate that when cutting depth is small enough, the K9 glass can be machined in ductile mode and a relatively smooth machined surface without crack can be obtained. The chip is always in irregular and discontinuous way no matter what the cutting mode is. Three cutting tools with different rake angle were used in simulation and the effect of rake angle is analyzed. [ABSTRACT FROM AUTHOR]

Recently, many researchers and practitioners have shown interest on profile monitoring as a relatively new subarea of statistical process control. One main reason for this interest, and perhaps a key factor for the contributions of many researchers to this field, is the various applications of profile monitoring in real life. Although one can easily encounter many univariate applications of profile monitoring in service and manufacturing environments, there exist situations where quality of a product or process needs to be modeled in multivariate terms. In this paper, we investigate monitoring of multivariate simple linear profiles in phase II when independence assumption of observations within profile is violated. A remedial measure based on a transformation method is proposed to remove the autocorrelation structure within multivariate profiles, and numerical simulation is used as a vehicle to evaluate the effect of the proposed solution. Finally, a case study is considered to show the application of the model in practice. [ABSTRACT FROM AUTHOR]

This paper deals with tool wear in milling operation using carbide tools. The main purpose of this work is to define a model-based procedure for forecasting tool-wear progression during cutting operation by using machining simulation. Firstly, a multi-axis machining simulation algorithm is proposed based on DEXEL model and local area update method. NC milling machining process simulation software NCToolWearSim is realized by using Visual C++ and OpenGL. The developed process simulation software is used to simulate the cutting process. Secondly, tool-wear simulation algorithm in the machining process is presented with tool-wear model and machining simulation algorithm and is implemented into the machining simulation software NCToolWearSim in order to evaluate the tool wear and to update the tool geometry. The tool-wear value is estimated according to the established tool-wear model from experienced tool-wear data. Thus, tool-wear progression can be visualized in milling operation by using NCToolWearSim. Finally, experimental tests, performed milling integral wheel with carbide tools, were used to calibrate and validate the correctness of tool-wear simulation process based on the tool-wear model. [ABSTRACT FROM AUTHOR]

In this paper, temperature results obtained by numerical simulations based on three different methods of defining the heat flux load distribution are compared to directly measured temperatures acquired using infrared camera measurement techniques. The heat flux calculations are based on recorded instantaneous grinding power, average grinding power, and power calculated by multiplying the measured tangential forces and the cutting velocity (referred to as calculated power). The results show that the method applied to characterize the input flux load in the numerical model has a significant effect on the estimated grinding temperatures and that the calculated power data produce the best temperature results. [ABSTRACT FROM AUTHOR]

The effective modelling of configurable products must handle the complex problem of representation of the configurable products, learning new configurable products and analysis of their behaviour. However, currently in advanced CAD systems, there exists no systematic and effective method for designing configurations and integrating behavioural aspects and simulations. This paper proposes and develops a grammar-based design approach to support both the computer-aided design for configuration and computing in CAD systems. Two interrelated questions are taken into account: (1) What are the hypothesis, properties and features for product configuration? (2) How can the product based on configuration features be represented and how can the configuration representation method integrate the numerical computing in design? This approach, under the guide of the proposed formal modelling, is implemented in computers. A design case study illustrates the proposed approach. [ABSTRACT FROM AUTHOR]

Machining along continuous circular tool-path trajectories avoids tool stoppage and even feed rate variation. This helps particularly in high-speed milling by reducing the effect of the machine tool mechanical structure and cutting process dynamics. With the increase in popularity of this machining concept, the need for detailed study of a valid chip formation in circular end milling is becoming necessary for accurate kinematic and dynamic modeling of the cutting process. In this paper, chip formation during circular end milling is studied with a major focus on feed per tooth and undeformed chip thickness along with their analytical derivations and numerical solutions. At first, the difference in the feed per tooth formulation for end milling along linear and circular tool-path trajectories is presented. In the next step, valid formulation of the undeformed chip thickness in circular end milling is derived by considering an epitrochoidal tooth trajectory with a wide range of the tool-path radius. The complex transcendental equations encountered in the derivation are dealt with, by a case-based approach to obtain closed-form analytical solutions. The analytical solutions of undeformed chip thickness are validated with results of numerical simulations of tool and tooth trajectories for circular end milling and also compared to the linear end milling. The close resemblance between analytical and numerical calculations of the undeformed chip thickness in circular end milling suggests validity of the proposed analytical formulations. As a case study, the cutting forces in circular end milling are calculated based on the derived chip thickness formulations and an existing mechanistic model. The calculation results reiterate the need of taking into account adjusted feed per tooth and valid chip thickness formulations in circular end milling, especially for small tool-path radii, for more realistic process modeling. [ABSTRACT FROM AUTHOR]

The existing numerical simulations of hydrodynamic characteristics of abrasive waterjet in a cutting head were mainly based on Eulerian grid or arbitrary Lagrange-Eulerian grid method to establish computational fluid dynamics models. However, using these two methods, the abrasive and water were premixed and given an identical initial velocity, which were different from the mixing and acceleration processes of abrasive in the cutting head. This paper presents a more suitable numerical model that the abrasive particle enters into the mixing chamber in a low velocity and is accelerated in the focus tube by a high-speed waterjet from the orifice. In order to model this mixing-and-acceleration process of abrasive and high-speed waterjet, the smooth particle hydrodynamics (SPH) coupled finite element method (FEM) is adopted, in which SPH particles are used to model the high-speed waterjet to adapt its extremely large deformation and FEM is applied to model the discrete abrasive particle, cutting head, and workpiece. As a result, evolution of abrasive and waterjet velocities along focus tube is analyzed; trajectory of single abrasive particle in focus tube is sighted; the relationships between abrasive particle velocities and different water pressures are described; the rule of outlet velocities of abrasive particle vs. dimensionless ratio of diameter is conducted; depth of penetration caused by single abrasive particle impact is obtained. The current model is validated by the existing theoretical and experimental data. [ABSTRACT FROM AUTHOR]

A grinding process model for an automatic grinding system with grinding force control is developed in this paper. This grinding system utilises an electric hand grinder, driven by a CNC machine centre and a force sensor for force measurement. This model includes compliance of the grinding system and is initially represented by a series of springs. The stiffness of each component is estimated in this study and it is found that the model may be simplified into a single spring-mass system. A corresponding PID controller is designed for the purpose of grinding force control, which calculates the appropriate CNC spindle displacement according to the force measured by the force sensor. Computer simulation results show that the system settling time is less than 0.25 s. [ABSTRACT FROM AUTHOR]