bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards the Design of Compliant Continuum Topologies With Geometric Nonlinearity
Authors: Saxena A. , Ananthasuresh G. K.
Published: February 2021

Optimal design methods that use continuum mechanics model for the deformation of the elastic body, are capable of generating suitable topology, shape, and dimensions of compliant mechanisms for desired specifications. Elastic analysis with linear finite element models employed in the synthesis procedures to date is not quantitatively accurate for large displacement situations. Also, the design specifications involving nonlinear force-deflection characteristics and generation of a curved path for the output port are difficult to realize with linear models. In this paper, the synthesis of compliant mechanisms is performed using geometrically nonlinear finite element models that appropriately account for large displacements. Frame elements are chosen for developing the synthesis procedure because of ease of implementation of the general approach and their ability to capture bending deformations. A computationally efficient method for computing the nonlinear design sensitivities is described. Examples are included to illustrate the usefulness of the synthesis method.
Constraint Handling and Iterative Attribute Model Building in Decision-Based Engineering Design
Authors: Iyer Harikumar , Tang Xiao , Krishnamurty Sundar
Published: February 2021

This paper deals with two major issues that are central to the development and implementation of decision-based approaches to engineering design, namely, the treatment of constraints and accurate preference representation. In this paper, a decision analysis based constraint handling technique is introduced that will be particularly useful in constrained engineering problems with multiple attributes. Recognizing the iterative nature of engineering design where design alternatives may not always be known a priori (unlike in traditional engineering design), this paper introduces the concept of knowledge-influenced attribute model building as a means to update preference representation for the purposes of accurately reflecting designer’s intent and purposes throughout. the evolving design process. These two concepts are then used to extend the TRED (Trade-off based Robust Engineering Design) framework that has been developed as a formal design strategy through the integration of utility theory, based multiattribute models into a Taguchi philosophy based design of experiments setup. Here, to find robust optimal solutions to constrained engineering design problems, this paper presents the development of a second order design space reduction technique based on Response Surface Methodology (RSM). Its application to engineering problems is illustrated through a simple case study and the results are discussed.
Modeling Three Dimensional Tolerance Zones Using Screw Parameters
Authors: Desrochers Alain
Published: February 2021

This paper presents a mathematical representation of the three dimensional tolerance zones defined in the ANSI Y14.5 M standard. The tolerance zone models are based on the small displacement screw which is a screw parameter expressing first order approximation of traditional homogeneous transformation matrix. Modeling of datum system and complex surface association is also taken into account as well as modeling of multiple tolerance specifications and material modifiers. Application of the representation model is presented on a simple tolerance transfer case where emphasis is put on the translation components of the tolerance zones. The screw parameter representation is also compatible with the Technologically and Topologically Related Surfaces (TTRS) representation model.
A Comprehensive Robust Design Approach for Decision Trade-Offs in Complex Systems Design
Authors: Kalsi Monu , Hacker Kurt , Lewis Kemper
Published: February 2021

In this paper we introduce a technique to reduce the effects of uncertainty and incorporate flexibility in the design of complex engineering systems involving multiple decision-makers. We focus on the uncertainty that is created when a disciplinary designer or design team must try to predict or model the behavior of other disciplinary subsystems. The design of a complex system is performed by many different designers and design teams, each of which may only have control over a portion of the total set of system design variables. Modeling the interaction among these decision-makers and reducing the effect caused by lack of global control by any one designer is the focus of this paper. We use concepts from robust design to reduce the effects of decisions made during the design of one subsystem on the performance of the rest of the system. Thus, in a situation where the cost of uncertainty is high, these tools can be used to increase the robustness, or independence, of the subsystems, enabling designers to make more effective decisions. This approach includes uncertainty caused by control factor variation (Type II robust design) and uncertainty caused by unknown nonlocal design information (Type I robust design). To demonstrate the usefulness of this approach, we consider a case study involving the design of a passenger aircraft.
A Lean-Server Approach to Enabling Collaboration Using Advanced Design Methods
Authors: Hale Mark A. , Craig James I. , Mavris Dimitri N.
Published: February 2021

The design framework research community utilizes the internet as a facilitator for collaborative activities. The internet provides a platform independent interface and geographic distribution. Information can be easily represented to the end-user using the HyperText Markup Language and can be coded in a reasonable timeframe. A shortcoming of exploiting this technology further is the reliance on existing Web servers to interface with analysis tools and design services. In this case, interactive components require auxiliary processes (called CGI scripts) to be started by the server that are used in an inefficient manner. This model does not provide the user-oriented capability required by standalone applications. Java offers improvements in client-side processing but a server bottleneck still exists. A novel approach using lean-servers is introduced as an alternative method for providing an efficient server-side computing model. In this case, internet requests are brokered directly by the design application by providing a gateway to the application’s programming interface using a HyperText Transfer Protocol compliant layer. This allows requests to be managed directly by the application rather than requiring auxiliary services. Step-by-step directions for implementing this approach using a case study of an existing design framework are given in this paper. A prototype system, called the Systems Programming Architecture for Collaborative Engineering, is described as one scenario for implementing the lean-server technology. Usability of the approach is demonstrated through a Design of Experiments example that is representative of modern design methods. This example also demonstrates collaboration because it executes asynchronously with multi-user intervention at any time during the process. In hindsight, the lean-server approach is an enabling technology for collaborative design and focuses future research direction on the establishment of collaborative design practices.
Low-Degree B-Spline Approximation of Procedurally Defined Curves
Authors: Qu Jun , Sarma Radha
Published: February 2021

This paper outlines an algorithm for approximating procedurally defined curves with low-degree, integral b-spline curves. The algorithm is based on minimizing a least square error metric between the ideal and approximated curves. Expressions for optimality criteria using the least square error metric are derived from a combination of exact b-spline integration and numerical integration techniques, thereby eliminating the need for sampling the ideal curve. A high-level iterative procedure that doubles knots at each step is proposed to ensure that the deviations between the ideal and approximated curves are within user specified limits. Issues of computational complexity are addressed and several examples are presented that illustrate the effectiveness of the algorithm.
Optimal Design and Control of an Electric DC Motor
Authors: Reyer Julie A. , Papalambros Panos Y.
Published: February 2021

In the design and optimization of artifacts requiring both mechanical and control design, the process is typically divided and performed in separate steps. The physical structure is designed first, a control strategy is selected, and the actual controller is then designed. This paper examines how this separation could affect the overall system design and how the combination of the separate problems into a single decision model could improve the overall design, using an electric DC motor as a case study. The combination is challenging since the two problems often have different design criteria and objectives and mathematical model properties. A Pareto analysis is suggested as a rigorous way to compare a variety of design scenaria.
Encapsulated Transmission of Part Specifications for Distributed Solid Freeform Fabrication
Authors: Storti Duane , Redl Chad , Ganter Mark , Turkiyyah George , Woo Tony
Published: February 2021

This paper describes an approach to the transmission of part specifications for distributed solid freeform fabrication. We consider an approach motivated by recent advances in software development associated with object oriented programming style and data encapsulation. Rather than insisting on translation of part specifications to a standard format, we specify a set of public methods necessary for solid freeform fabrication (SFF) or layered manufacturing (LM). By specifying public members and methods that provide fabrication systems with all the information needed to build parts, SFF systems can build parts based on models constructed in any modeling environment for which the methods are available.

As an example, we consider a candidate set of methods required by a simple layered fabrication system, and we discuss an implementation of those methods for a modeling format, implicit solid modeling, that has not previously been directly supported by SFF systems. Since for any modeling system, SFF relies on the construction of the layers or slices through the part, we pay particular attention to describing a slicing implementation for implicit solids.
On the Exact Representation of the Boundary Surfaces of the Swept Volume of a Cylinder Undergoing Rational Bézier and B-Spline Motions
Authors: Xia J. , Ge Q. J.
Published: February 2021

This paper develops methods for the exact analysis and representation of the swept volume of a circular cylinder undergoing rational Bézier and B-spline motions. Instead of following the traditional approach of analyzing the point trajectory of an object motion for swept volume analysis, this paper seeks to develop a new approach to swept volume analysis by studying the plane trajectory of a rational motion. It seeks to bring together recent work in swept volume analysis, plane representation of developable surfaces, as well as computer aided synthesis of freeform rational motions. The results have applications in design and approximation of freeforms surfaces as well as tool path planning for 5-axis machining of freeform surfaces.
Magnetic Bearing Design Using Genetic Algorithms
Authors: Teng Yong , Carlson-Skalak Susan , Maslen Eric
Published: February 2021

A magnetic bearing system is a coupled, nonlinear, high-dimensional system. The relationship among the design parameters, design constraints and the optimization goals is not obvious. Solving this type of design problem within a reasonable time frame is a challenge for any optimization method. This research investigated the simultaneous optimization of the magnetic bearing configuration and bearing locations. A multistage genetic algorithm was developed to search through a discrete and non-convex solution space. Because the genetic algorithm can search through a much larger solution space than any engineer can do, innovative designs different from those using traditional methods can be found.
A Decision Support Model for the Life-Cycle Design of a Family of Oil Filters
Authors: Ortega Roberto A. , Kalyan-Seshu Uma-Shankar , Bras Bert
Published: February 2021

In this paper, a decision support approach for designing a family of environmentally benign products for a ranged set of customer requirements is presented. More specifically, we incorporate environmental issues in order to minimize the environmental impact of products without sacrificing their performance characteristics and keeping competitive prices in comparison to existing products. The example problem consists of the design of a family of environmentally benign oil filters based on a variety of oil flow rate ranges. Environmental issues are represented by Life Cycle Assessments and comparisons of the existing alternatives based on their environmental impact. Emphasis is placed on highlighting the trade-off analysis for including environmental considerations in the design of a family of products and not on the results of the problem, per se.
Real-Time Finite Element Modelling With Haptic Support
Authors: Berkley Jeffrey , Ganter Mark , Weghorst Suzanne , Gladstone Hayes , Raugi Gregory , Berg Daniel
Published: February 2021

This paper presents the preliminary results of a new real-time finite element system which supports haptic (i.e. force) feedback to the user. The methodology of the system is based on linear finite-element analysis. Further, this system was originally developed as part of a real-time skin surgery simulator with the Human Interface Technology Lab and, the Division of Dermatology at the University of Washington Medical School. We are currently exploring its use and development as a new engineering design tool.
Fitting Functions to Data in High Dimensional Design Space
Authors: Wang Xiaoou , Liu Yingying , Antonsson Erik K.
Published: February 2021

One approach to rapidly exploring large design spaces is to evaluate the performance of a small number of representative points in the space, then based on those points, construct an approximation to the response over a region of interest. Linear, piecewise linear, quadratic and multivariate adaptive regression splines (MARS) models are fit to an example 5-dimensional data set representative of information available in preliminary engineering design. When the number of data points representing a high-dimensional response is small, all of the approximation models appear to perform nearly equally.
Multiple-Points Constraints Based Deformation for Free-Form Surfaces
Authors: Zheng J. M. , Chan K. W. , Gibson I.
Published: February 2021

There is an increasing demand in the conceptual design for more intuitive methods for creating and modifying free-form curves and surfaces in CAD modeling systems. The methods should be based not only on the change of the mathematical parameters but also on the user’s specified constraints and shapes. This paper presents a new surface representation model for free-form surface deformation representation. The model is a combination of two functions: a displacement function and a function for representing an existing NURBS surface called parent surface. Based on the surface model, the authors develop two deformation methods which are named SingleDef (Single-point constraint based deformation method), and MultiDef (Multiple-points constraints based deformation method). The techniques for free-form surface deformation allow conceptual designer to modify a parent surface by directly applying point constraints to the parent surface. The deformation methods are implemented and taken in an experimental CAD system. The results show that the designer can easily and intuitively control the surface shape.
Smart Optimization of Machine Systems Using Hierarchical Genotype Representations
Authors: Yoshimura Masataka , Izui Kazuhiro
Published: February 2021

Design problems for machine products are generally hierarchically expressed. With conventional product optimization methods, it is difficult to concurrently optimize all design variables of portions within the hierarchical structure. This paper proposes a design optimization method using genetic algorithms containing hierarchical genotype representations, so that the hierarchical structures of machine system designs are exactly expressed through genotype coding, and optimization can be concurrently conducted for all of the hierarchical structures. Crossover and mutation operations for manipulating the hierarchical genotype representations are also developed. The proposed method is applied to a machine-tool structural design to demonstrate its effectiveness.
Two-Dimensional Trimmed Surface Development Using a Physics-Based Model
Authors: Wang Charlie C. L. , Chen Shiang-Fong , Fan Jin , Yuen Matthew M. F.
Published: February 2021

This paper presents a general method for parametric trimmed surface development. Parametric trimmed surface development is primarily used for flattening a 3D surface into a corresponding 2D pattern or surface. This method can be applied in computer aided design, texture mapping, ship building, etc. First, the surface is triangulated and mapped onto a plane. This initial planar mapping has the same topology as its original surface. Then, a spring-mass system is applied to deform the plane. The surface elastic deformation energy distribution is indicated by a color graph, which determines a surface cutting line. The method presented here can efficiently solve development problems for complex trimmed surfaces. Accuracy of a developed surface can easily be controlled locally. Thus, compared to earlier methods, this method provides more flexibility for solving CAD and CAM surfacing problems.
Task Distribution and Lumped Parameter Modeling in Multi-Disciplinary Product Development
Authors: Ozawa Masanori , Biswas Gautam , Zhu Liang
Published: February 2021

Present day electromechanical product design requires multi disciplinary design teams who have to perform complex synthesis, analysis, and control tasks to ensure desirable functional and performance characteristics for the products. In each stage of design, specialized tools are utilized to optimize design efficiency and product performance. Such tools tend to be used individually in an ad hoc manner. Moreover, the lack of uniform representations and the non availability of specific design data make it difficult for the different design groups to interact effectively and use the different design tools in an integrated fashion. This hinders the generation of globally optimal designs.

Typically design engineers construct Finite Element Methodology models (FEM models) for detailed analysis of phenomena in their individual domains (e.g., mechanical, thermal, etc.). In this paper, we argue the necessity for building more abstract lumped parameter models from distributed FEM models to facilitate model sharing and communication across multiple design teams. We describe a set of techniques for building lumped parameter system models from more detailed distributed models, and demonstrate their application in design problem solving. Finally, we propose the application of design-of-experience (DOE) and the Mahalanobis-Taguchi-System (MTS) with lumped parameter models.
Optimum Design Using Radial Basis Function Network and Adaptive Range Genetic Algorithms
Authors: Arakawa Masao , Nakayama Hirotaka , Ishikawa Hiroshi
Published: February 2021

In this paper, we use the radial basis function networks in order to approximate the fitness function of the genetic algorithms and try to obtain the approximate optimum results within the relatively small number of function call. The radial basis function network (RBF) is a kind of neural network that is composed by the number of radial basis function in Gaussian distribution. Its learning system is composed by additional learning of basis function and a new data and forgetting of basis function and undesirable data. Thus the key issues in RBF are to give new data and to place basis function. So that if we can give these values appropriately, we can carry out approximate optimization even in the case that the optimum solutions are outside the range of the initial settings. Together with the adaptive range genetic algorithms that are proposed to treat mixed variable optimization, we will propose the way to give a new data and basis function. In this study, we have shown the effectiveness of the proposed method through simple numerical examples.
Control Barriers of Positioning Manipulators
Authors: Abdel-Malek K. , Yeh Harn-Jou , Alkam Mohamad
Published: February 2021

Broadly applicable formulations for identifying control difficulties in positioning serial manipulators are developed based on the Implicit Function Theorem and acceleration analyses on singular surfaces. As a result, voids in the workspace are also identified. Rank deficiency conditions are applied to the positioning Jacobian with joint constraints included in the formulation. Geometric entities upon which the manipulator exhibits control difficulties are identified. These difficulties are associated with a admissible motion along a vector normal to the singular geometric entities. Definiteness properties of a quadratic form that is as a result of normal acceleration define control difficulties. Numerical examples are illustrated.
Workspace Analysis of 6-PRRS Parallel Manipulators Based on the Vertex Space Concept
Authors: Bonev Ilian A. , Ryu Jeha
Published: February 2021

This paper presents workspace analysis of 6–PRRS parallel manipulators based on the vertex space concept. A fully geometric algorithm is described for the computation of the constant-orientation workspace, which was implemented in the CAD/CAM system CATIA. The influence of the different design parameters on the workspace as well as on the other properties of the manipulator is discussed. Finally, examples are provided to demonstrate the usefulness of the proposed method.
C
3 Two-Harmonic Rational B-Spline Curves for Trajectory Synthesis
Authors: Ge Q. J. , Xia J. , Rastegar J.
Published: February 2021

This paper extends the recent work on rational Bézier representation of trigonometric polynomial curves to develop piece-wise two-harmonic curves with the third order (or C3) continuity. First, C3 continuity conditions are derived for piecing together two-harmonic rational Bézier curve segments. These conditions are then used to obtain C3 two-harmonic rational B-spline curves that have similarities to C3 quartic B-spline curves. Low-harmonic rational B-spline curves are compatible with the existing NURBS based CAD systems and can be used to synthesize low-harmonic motions of high-speed machinery to avoid vibration and control related problems.
Approximating Polynomial Bézier Curves Using Harmonic Rational Bézier Curves
Authors: Xia J. , Ge Q. J.
Published: February 2021

This paper deals with the problem of approximating polynomial Bézier curves with low-harmonic rational Bézier curves. It is shown that a polynomial Bézier curve is representable as a hybrid curve consisting of a low-harmonic curve with a moving control point. This hybrid representation leads directly to a low-harmonic approximation of a given polynomial curve. The approximation error is also analyzed. The result can be used to fine tune a polynomial trajectory for high-speed machinery to remove high harmonics from the trajectory.
Experimental Evaluation of a Criteria-Based Obstacle Avoidance Scheme
Authors: Harden Troy , Kapoor Chetan , Tesar Delbert
Published: February 2021

Obstacle avoidance allows manipulators to work in cluttered environments without damaging themselves or their environment. It generally involves collision prevention and configuration optimization to avoid obstacles, with collision prevention being the only choice for non-redundant manipulators. In the case of redundant manipulators, one obstacle avoidance scheme uses null-space options for a given end-effector location, and subsequent ranking of these options to select the ‘best’ one based on input criteria. Under this scheme, four obstacle avoidance criteria have been developed. These four (and other non-obstacle avoidance) criteria along with workspace modeling have been implemented as an extension of the OSCAR C++ software library. This library can be used to develop obstacle avoidance applications involving multiple manipulators operating in complex environments. Experimental evaluation of this scheme is conducted on a 17 degree of freedom dual-arm robotic manipulator, and results are presented.
Model Reference Learning Control for Rigid Robots
Authors: Guruprasad K. R. , Ghosal Ashitava
Published: February 2021

The equations of motion of a rigid robot are often known only approximately, as some of the parameters are not known exactly and there are also unmodelled nonlinearities. Most adaptive control schemes can estimate the parameters if the structure of the equations is known, but are not very useful if structure itself is not known.

In this paper we propose a model reference learning control scheme using Adaptive Network based Fuzzy Inference System (ANFIS) for control of rigid robots whose model may have parametric and structural uncertainties. The approximate model of a robot, which may differ very significantly from the actual robot in parametric values and structure, is used as a reference plant and a nonlinear model based controller is designed based on this model. The ANFIS corrector provides an additional correction to control input as a function of the present and desired states of the plant. The error between states of plant and that of reference plant is used to tune the ANFIS corrector.

The proposed control scheme has been implemented for a two-degree-of-freedom serial rigid robot. The results of the simulation experiments carried out show that the proposed control scheme can learn to control the unmodelled dynamics. The ANFIS controller is shown to give improved performance for parameter as well as structural uncertainties.
A New Approach in Solving Bennett Mechanism
Authors: Khan Mahmood A.
Published: February 2021

This paper explores the geometry of the Bennett linkage. Bennett, in the year 1903, invented a 4-R spatial linkage with two remarkable characteristics i.e. with 4 non-parallel and non-concurrent joint axes, has mobility one. In this paper the relationship among the intensities of the twists, i.e. four skew axes of the Bennett, and the perpendicular distances among the opposite skew axes of the Bennett linkage is established. The geometry of the three revolute joint axes of the Bennett Mechanism, one of the classical screw 3-system (Hunt (1978)), are not only skew but are independent to each other.
An Integrated CAD/CAM System for Design and Manufacturing of High-Curvature Surfaces
Authors: Wang Liping , Nair Subramaniam S.
Published: February 2021

This paper presents an integrated CAD/CAM system developed at the City College of the City University of New York (CCNY) for design, analysis and manufacturing of high-curvature surfaces. Surface modeling technique which is characterized by modeling from curvature or slope information, is discussed and practiced to design high-curvature surfaces such as rear-view mirror covers for automobiles. Plastic molding is chosen to manufacture the designed parts. Molding parameters such as entrance position and mold inserts are analyzed and determined using tools such as mold filling analysis (C-FLOW/EZ). Newly modified curvature matching method, together with methods provided by commercial CAM software, are adopted to generate five-axis NC tool path to manufacture the designed mold components. An example on design and manufacturing of a rear-view mirror cover using the integrated CAD/CAM system for high-curvature surfaces is given to illustrate the effectiveness of this system.
Design of a Parallel Manipulator With an Orthogonal Configuration
Authors: Tsai Lung-Wen
Published: February 2021

In this paper, the design of a 6–6 Stewart–Gough platform with an orthogonal configuration is presented. First, a geometric construction of the manipulator is described. Then, it is shown that translational motion of the moving platform can be achieved by programming the limb lengths such that they form three pairs of spatial parallelograms. The Jacobian and stiffness matrices are derived. Finally, it is shown that, at the orthogonal location, the stiffness matrix of the manipulator reduces to a diagonal form. Hence, translational stiffness of the manipulator is completely decoupled from torsional stiffness.
Contention-Free Control of Over-Constrained Variable Geometry Trusses
Authors: Soper R. Randall , Reinholtz Charles F. , Canfield Stephen L. , Williams Robert L.
Published: February 2021

A unified velocity analysis approach for Variable Geometry Trusses (VGTs) is employed to develop a direct strategy for actuator contention avoidance in over-constrained architectures. Techniques of matrix theory are used to meet all boundary and structural constraints simultaneously. The null-space of a square matrix of dimension equal to the number of actuators forms a basis for contention-free trajectories.

Further, the unified velocity analysis procedure, is modified to improve efficiency in the case of open serial chains of truss-type or truss-like manipulators. When applied to over-constrained architectures, an iterative velocity analysis procedure results.
Kinematic Synthesis of Spatial R-R Dyads for Path Following Revisited Using the Rotation Matrix Approach
Authors: Krovi Venkat , Ananthasuresh G. K. , Kumar Vijay
Published: February 2021

We revisit the dimensional synthesis of a spatial two-link, two revolute-jointed serial chain for path following applications, focussing on the systematic development of the design equations and their analytic solution for the three precision point synthesis problem. The kinematic design equations are obtained from the equations of loop-closure for end-effector position in rotation-matrix/vector form at the three precision points. These design equations form a rank-deficient linear system in the link-vector components. The nullspace of the rank deficient linear system is then deduced analytically and interpreted geometrically. Tools from linear algebra are applied to systematically create the auxiliary conditions required for synthesis and to verify consistency. An analytic procedure for obtaining the link-vector components is then developed after a suitable selection of free choices. Optimization over the free choices is possible to permit the matching of additional criteria and explored further. Examples of the design of optimal two-link coupled spatial R-R dyads are presented where the end-effector interpolates three positions exactly and closely approximates an entire desired path.
On the Dynamic Behavior of High Speed Mechanical Systems
Authors: Yuan L. , Rastegar J.
Published: February 2021

This article reports a study of the steady state behavior of mechanical systems with nonlinear dynamics in the presence of dynamic response limitations of the actuation mechanism and in the presence of structural flexibility. In particular, the effects of such dynamic response limitations on the periodicity of the system response are studied and conditions for the existence of periodic solutions are derived. The structural flexibility is shown to increase the number of significant harmonics of the required actuating torques. A number of examples together with computer simulation results verifying the aforementioned results are presented.
Multicriteria Optimization in Product Platform Design
Authors: Nelson Sigurd A. , Parkinson Matthew B. , Papalambros Panos Y.
Published: February 2021

A product platform is a set of common components, modules or parts from which a stream of derivative products can be created. Product platform design requires selection of the shared parts and assessment of the potential sacrifices in individual product performance that result from parts sharing. A multicriteria optimization problem can be formulated to study such decisions in a quantitative manner at the product performance level. Studying the Pareto sets that correspond to various derivative products leads to a systematic methodology for design decision making. A brad-nail gun is used to illustrate the concepts presented.
A Distributed Approach for Accessibility and Maintainability Check With a Manikin
Authors: Chedmail Patrick , Roy Christophe Le
Published: February 2021

The validation of the accessibility, maintainability, mounting/dismantle simulation in a cluttered environment is a key problem during the design process of a mechanical system. On the one hand research in path planning lead to automatic trajectory definition. These systems are really efficient for simple problems. On the other hand direct manipulation is possible thanks to robotic CAD systems. Another direct manipulation is possible with common virtual reality tools that allow the designer immersion in a whole mechanical environment. In such an environment the designer can handle an object in order to check its accessibility. Thanks to the use of a multi-agent architecture we greatly improve the effectiveness of virtual reality tools while coupling algorithmic approaches and direct manipulation. This original method is a solution of a multi-criteria constrained optimisation problem. Theoretical and practical aspects are presented.
Validation of the Tolerance Analysis of Compliant Assemblies
Authors: Sellem Eric , Rivière Alain , De Hillerin Charles André , Clement André
Published: February 2021

Current statistical tolerance analysis of assemblies are generally based on Monte Carlo simulation or Worst Case. The available software tools using this technique model the assembly of rigid parts, by only considering the kinematic laws. Sellem (1998) proposed a linear mechanical model taking both deformation and assembly process into account in the computation of tolerance assemblies of compliant parts. This paper presents the validation of this method by a comparison with measurements performed on an actual assembly of four complex parts. Some improvements in the modeling of the assembly process are also presented and described a sensitivity analysis approach to identify the key characteristics of the assembly.
Position Analysis in Analytical Form of the 3-PSP Mechanism
Authors: Di Gregorio Raffaele , Parenti-Castelli Vincenzo
Published: February 2021

In this paper the direct and the inverse position analysis of a 3-dof fully-parallel mechanism, known as 3-PSP mechanism, is addressed and solved in analytical form. The 3-PSP mechanism consists of two rigid bodies, one movable (platform) and the other fixed (base), connected to each other by means of three equal serial kinematic chains (legs) of type PSP, P and S standing for prismatic and spherical pair respectively. Both the direct and the inverse position analysis of this mechanism lead to non-linear equations that are difficult to solve. In particular, the inverse position analysis comprises different sub-problems which need specific solution techniques. Finally a numerical example is reported.
A Feature Library and an Algorithm for Design of Parts Machinable in Four-Axis CNC Lathes
Authors: Arikan M. A. Sahir , Sander Tolga Ziya
Published: February 2021

A feature library, an algorithm, and an interactive computer program are developed for design of parts machinable in four-axis CNC lathes with milling capabilities. Parts can be checked, visualized, manipulated and modified during or after the design. Previously designed parts can be retrieved and modified for design of new similar parts. The feature library comprises features for turning and related operations; features for planar milling operations to remove material from the cylindrical surface or from the face of the workpiece; features for cylindrical milling operations to remove material from the cylindrical surface of the workpiece; features for boring and related operations; features for single and patterned holes, and hole operations, such as, center drilling, drilling, boring, reaming, groove cutting, tapping, counterboring, countersinking and spotfacing, and features for detail operations such as external and internal threading, external and internal helical groove cutting, knurling and machining of various slots. Parts are designed by using a hybrid algorithm. The main geometry of the part is formed by using the primary operations. For this, parametrically modeled primitives are retrieved from the library, and joined by using union operations. Then, milling, boring and hole operations and details are included again by using parametrically modeled features and subtraction operations as the secondary operations. Blank geometry, which can be a circular, hexagonal, square or rectangular bar; or a part made by forging or casting is defined again by using operations on available primitives. All of the features contain information on process sequencing, cutting tools, tool paths, machining parameters and G-codes. Thus, when the design of the part is completed, information for generation of the CNC program becomes readily available.
Design and Control of Forming Processes Using Optimization Techniques
Authors: Ghouati O. , Lenoir H. , Gelin J. C. , Baida M.
Published: February 2021

The paper deals with the design and control of forming processes. The finite element code used is based on isoparametric shell elements with three or four nodes, the workpiece being considered as a sheet metal. An optimization technique is used in order to achieve the design or the control of the process by determining the optimal process parameters. The criterion used in that purpose can be based on thickness distribution as well as the respect of the final shape desired for the product. Numerical examples are presented as illustration.
Automatic Coordinate Measuring Machine Inspection
Authors: Albuquerque V. A. , Liou F. W. , Agarwal S. , Mitchell O. R.
Published: February 2021

In many industrial applications, such as product prototype development, automation of inspection process can greatly improve product quality and product development cycle, time. This paper discusses a development of a vision aided automatic inspection using Coordinate Measuring Machine (CMM). We seek to integrate the flexibility afforded by computer vision systems with the precision of numerically controlled coordinate measuring machines to achieve a fully automatic and reliable inspection of the industrial parts. The 3-D design information and part specification from computer-aided design file is used for inspection point placement and CMM path planning. The proposed system demonstrates that optimal collision-free inspection paths can be efficiently generated for geometrically complex parts consisting of multiply intersecting features. This is made possible by using iterative subdivision of surfaces for point placement coupled with, efficient 3-D collision avoidance and path planning. The paper discusses different algorithms used, and presents experimental results.
Automated Punch Shape Synthesis for Sheet Metal Bending Operations
Authors: Alva Ujval , Gupta Satyandra K.
Published: February 2021

Sheet metal bending is a process in which bends are formed using a combination of a punch and a die. A very large number of mechanical products such as furniture panels, shelves, cabinets, housing for electro-mechanical devices etc. are created by using the sheet metal bending process. Bending tools need to satisfy the following two criteria: (1) tools should be able to withstand bending forces, and (2) tool shapes should be such that there is no tool-part interference. In this paper, we describe a systematic methodology for automatically synthesizing shapes of bending punches. We create parametric geometric models of punches. These parametric models describe the family of possible punch shapes. Using the part geometry and parametric punch shape models, we automatically generate constraints on tool parameters that eliminate the possibility of part-tool interference. We use mixed integer programming techniques to identify parameters of punch shapes that result in the maximum punch strength. Finally, we perform strength analysis of the designed punch shape to verify that the designed punch shape is capable of withstanding the bending forces.
Manufacturability Analysis for Solid Freeform Fabrication
Authors: Arni R. K. , Gupta S. K.
Published: February 2021

This paper describes a systematic approach to analyzing manufacturability of parts produced using Solid Freeform Fabrication (SFF) processes with flatness, parallelism and perpendicularity tolerance requirements on the planar faces of the part. SFF processes approximate objects using layers, therefore the part being produced exhibits stair-case effect. The extent of this stair-case effect depends on the angle between the build orientation and the face normal. Therefore, different faces whose direction normal is oriented differently with respect to the build direction may exhibit different values of inaccuracies. We use a two step approach to perform the manufacturability analysis. We first analyze each specified tolerance on the part and identify the set of feasible build directions that can be used to satisfy that tolerance. As a second step, we take the intersection of all sets of feasible build directions to identify the set of build directions that can simultaneously satisfy all specified tolerance requirements. If there is at least one build direction that can satisfy all tolerance requirements, then the part is considered manufacturable. Otherwise, the part is considered non-manufacturable. Our research will help SFF designers and process providers in the following ways. By evaluating design tolerances against a given process capability, it will help designers in eliminating manufacturing problems and selecting the right SFF process for the given design. It will help process providers in selecting a build direction that can meet all design tolerance requirements.
PMM: Process Module Methodology for Integrated Design and Assembly Planning
Authors: Bichlmaier Christoph , Grunwald Stefan
Published: February 2021

Competitive products are the key to the success of every company. To resist the pressure of high competition companies must also optimize their processes to an even greater extent.

Apart from the direct production departments such as manufacturing and assembly, where the optimization of production processes have been standard practice for decades, the indirect areas such as product development and planning of production systems are now moving increasingly to center-stage. Alongside the requirement for innovation, these areas are expected to keep to schedule and cost restrictions. But the high degree of complexity of the process steps involved and the difficulty of accurately defining them prevent effective process management in these areas. Experience from industry shows that companies desire a lot of support in these areas.

The following paper describes an innovative methodology for the flexible planning, monitoring and controlling of highly complex dynamic development processes. This methodology, has already proved successful in pilot projects in different industries such as automobile or electrical tool industry.
Layered Manufacturing With Embedded Components: Process Planning Considerations
Authors: Cham Jorge G. , Pruitt Beth L. , Cutkosky Mark R. , Binnard Mike , Weiss Lee E. , Neplotnik Gennady
Published: February 2021

This paper addresses the design and manufacturing of products with embedded components through layered manufacturing processes such as Shape Deposition Manufacturing (SDM). Embedding components allows the creation of novel designs such as “smart” products and integrated assemblies of sensors, actuators and other mechanical components. We present prototypes to illustrate the possibilities for such devices and we address the issues that constrain their process planning. Next, we present a combination of process planning algorithms and manufacturing methods that we have developed to support the design of layered products with embedded components.
Cost Estimation for Process Selection
Authors: Esawi Amal M. K. , Ashby Michael F.
Published: February 2021

In selecting a process to make a given component, it is first necessary to screen available processes to find those which can make the desired shape from the desired material with the desired precision and finish. Commonly, many processes survive this screening, and it is then desirable to rank them approximately so that the most promising are explored first. The natural criterion for ranking is that of relative cost. This paper describes an approximate relative cost model, applicable to all processes, designed to give this approximate ranking. It is based on summing the costs of material, energy, time, capital and other resources. The values for equipment cost, tooling cost and production rate depend on component size and complexity. Approximate scaling methods are used to include these dependencies. The model has been implemented in a Process Selector (the CPS) and fills its intended function adequately.
Incorporating Process Planning Into Conceptual Design
Authors: Feng Shaw C. , Nederbragt Walter W. , Kaing Serge , Sriram Ram D.
Published: February 2021

This paper describes recent developments in the Design and Process Planning Integration (DPPI) project at the National Institute of Standards and Technology (NIST). The project addresses the need for improved communication between design and process planning in the early product design stage. Since major manufacturing costs are committed during product specification and design, it is critical to successfully assess manufacturability and cost as early as possible in the design process. Documenting the DPPI foundation, this paper reviews industry needs for an integrated design and manufacturing environment for rapid product development. Additionally, this paper describes the project’s approach and the current status. Conceptual design and process planning prototype systems, that have been implemented, are also described. Finally, it describes the future direction for developing mechanisms to enable the integration of design and process planning, including information models and language interface specifications.
A Formative Evaluation of a Feature Extraction and Process Planning Tool
Authors: Gaines Daniel M. , Hayes Caroline C.
Published: February 2021

It is a common problem that many computer tools intended to enhance human performance in design or manufacturing planning do not do so. In many cases they may actually degrade performance. One way to increase the probability that a tool will meet users needs is to include frequent periodic usability assessments in the development process so feedback from users can be incorporated in new iterations of the software design. This paper describes an example of one such assessment applied to a Mediator, a feature extraction and process planning tool for assisting process planners to explore plan options more quickly and thoroughly. There exists a wide variety of usability assessment techniques which can mostly be divided into two broad categories: summative evaluations which provide in-depth assessments in the final stages of software development, and formative evaluations which tend to be smaller in scale and are used to provide guidance for “forming” subsequent software versions during the development cycle. In this work, we describe a formative usability assessment. The study indicated that Mediator was meeting its design goal of broadening the users exploration of manufacturing options, in some cases producing high quality manufacturing options which the expert users had not considered on their own. The study also provided formative redesign information gleaned which will help future versions of Mediator to better meet the actual needs of process planners.