bluuebunny/crossref_metadata_2025 huggingface dataset:
Elasto-Plastic Impact: Non-Linear FEA vs. Experimental Results
Authors: Werner Todd C. , Suchora Daniel H.
Published: February 2021

This paper analyzes the problem of a weight with a specified initial velocity impacting the end of an aluminum cantilever beam. The impact is severe enough to cause significant plastic bending strains in the beam. The impact is modeled using the Algor Event Simulation Non-linear Finite Element Analysis software using 21 node brick elements and a Von-Mises material model with isotropic hardening. Raleigh damping is included in the simulation.

The computer generated strain vs. time results are compared to traces obtained from a strain gage instrumented beam subjected to the impact modeled by the software. The comparison of the non-linear FEA computer results and the experimental data shows good correlation.
Parameter Identification of Inelastic Structures
Authors: Zhang H. , Yang Y. , Foliente G. C. , Ma F.
Published: February 2021

Structures often exhibit nonlinear and inelastic behavior in the form of hysteresis loop under severe loads associated with earthquake, austere winds and waves. Hysteresis is particularly important in depicting the nonlinear response of wood buildings, braced steel frames, reinforced concrete, and structures with a high proportion of composite materials. A practical model of hysteresis that would match experimental observations on real structures is needed for the successful design of structures against earthquakes and strong winds. Two different time-domain system identification algorithms will be presented in this report to estimate the parameters of an extended Bouc-Wen hysteretic model. This version of the differential model of hysteresis can curve-fit practically any hysteresis trace with a suitable choice of the model parameters. Thirteen control parameters are included in the model. The parameter identification algorithms presented in this report include the constrained simplex and generalized reduced gradient methods. Noise filtering techniques and constraints will also be used in this study to assist in parameter identification. The effectiveness of the proposed algorithms will be demonstrated through simulations of nonlinear systems with pinching and degradation characteristics. Due to very modest computing requirements, the proposed identification algorithms can be acceptable as a basic tool for estimating hysteretic parameters in engineering design.
Automated Determination of Spur Gear Form Factors
Authors: Overman Thomas M. , Shoup Terry E.
Published: February 2021

This paper presents a method for determining the form factor (J) and other form factors, which eliminates the need for manual table lookups to AGMA 908-B89 when designing spur gears. It provides an implementation of the algorithms presented in that earlier paper, in an easy-to-use spreadsheet module in Microsoft Excel 97. The implementation also allows form factor calculation for gear teeth combinations not given in the tables of 908-B89, thus eliminating the work of interpolating or extrapolating the tables in that earlier paper.
Generalized Algorithms for Interactive Warping Analysis of Porous Cross Sections
Authors: Pao Y. C. , Ritman Erik L.
Published: February 2021

Algorithms have been developed for warping analysis and calculation of the shearing stresses in a general porous cross section of a long rod when it is subjected to twisting torques at its ends. The shape and dimensions of the cross section full of holes are defined from the binary segmented image data with by a micro-CT scanning technique. Finite difference approximation of the Laplace equation governing the cross-sectional warping leading to the matrix solution by a Gauss-Seidel process is discussed. Method of pointer matrix which keeps the locations of the nonzero elements of the coefficient matrix, is employed to expedite the iterative solution. Computer programs are coded in QuickBASIC language to facilitate plotting of the computed distributions of warping and shearing stresses. The classical torsional problem of square and thin-walled cross sections are used to reexamine the accuracy of the developed algorithms and results are found to be in very good agreement.
Enabling Distributed Data Processing for Internet Analysis With GenX
Authors: Scholand Andrew J. , Peak Russell S. , Fulton Robert E.
Published: February 2021

This paper describes how an XML mapping of a product neutral standard, GenCAMsm, has been used in combination with a JavaScript XML parser to enable product-data driven analysis from a web interface. This client side processing of detailed design data results in greater accuracy of analysis inputs, lower Internet bandwidth requirements, and greater intellectual property security. The web interface lowers the barriers to use of sophisticated CAE analysis software, enabling tool use by product and process experts throughout the supply chain. An example illustration based on a Plated Through Hole thermomechanical analysis is presented. Application to an Internet-based Engineering Service Bureau is discussed.
Design Rules and Technology Guides for Web-Based Manufacturing
Authors: Inouye Ryan , Wright Paul K.
Published: February 2021

The paper establishes a set of machining rules for web-based manufacturing and discusses the guidelines for their classification and implementation. Rule checking is split into three levels, the Design Interface. Process Planning, and Machine Tool levels. Rules are placed in these different levels according the resources available and the inherent constraints of each level while maintaining their principle functionality. The implementation of rule checking on the CyberCut 3-D interface, a web-based manufacturing tool for machining, is discussed. The current implementation checks for the four most common conflicts between mechanical designers and manufacturing engineers.
Implementation of a Design Tool for Conceptual Design of Integrally Fastened Assemblies
Authors: Lee Paul G. , Lee Daeyong , Gabriele Gary A.
Published: February 2021

The proper use of integral attachment features in mechanical assemblies has been more of an art than an engineering science. An organized set of design steps for generating conceptual integral attachment designs has recently been developed based on work begun by Bonenberger. These steps outline a formal design methodology for exploring the design space of possible alternative attachment concepts. This paper describes the development of a software tool that attempts to implement the integral attachment design methodology to assist a designer in developing attachment concepts. The tool is implemented using the Java programming language. A graphical interface is used to present the methodology as a series of options that approximate the design situation. This hides many of the details of the methodology in favor of ease of use. The end result is a set of suggestions for integral fasteners that are matched to the design situation. A discussion of how the hundreds of images are handled using Java is provided. A sample case study illustrates the approach of the program. The tool represents one of the few examples of a design tool aimed specifically at generating design concepts.
Integrated Engineering, Geometric, and Customer Modeling: LCD Projector Design Case Study
Authors: Abrahamson Shaun , Wallace David , Senin Nicola , Borland Nick
Published: February 2021

This paper describes an integrated product design study conducted with Polaroid Corporation for a liquid crystal display video projector, applying a research system called DOME. The services of distributed objects — encapsulating CAE simulations, component catalogs, manufacturing cost models, geometric and configuration models, customer preference models, and environmental life-cycle assessment — are mathematically related to form an integrated product system model. Software objects providing optimization and decision support are also included in the model to create a design tradeoff environment. As such, designers can obtain sales predictions based upon configuration changes and make tradeoffs with other requirements. Benchmarking suggests there would be approximately a 30% increase in the time to fully evaluate the first design configuration due to the overhead of creating the integrated system model. However, the time to fully evaluate subsequent alternatives may be reduced from months to minutes.
Towards a Decision-Based Distributed Product Realization Environment for Engineering Systems
Authors: Gerhard Jonathan F. , Duncan Scott J. , Chen Yong , Allen Janet K. , Rosen David , Mistree Farrokh , Dugenske Andrew D.
Published: February 2021

We imagine a future in which geographically distributed engineers collaboratively develop, build, and test solutions to design-manufacture problems encountered in the product realization process. In this context, we want to provide a foundation to support the realization of industrial products for a global marketplace through distributed design and manufacture. Specifically, we want to provide a platform-independent framework to integrate distributed and heterogeneous software resources to support the computationally intensive activities in the product realization process, anchored in the philosophy of decision-based design. In this paper, we present a prototype platform-independent framework based on an experimental version, called P2, of the Sandia Product Realization Environment (PRE). We describe the implementation of this framework to design and prototype gear transmissions using commonly available software assets.
Application of Neural Network in Free Air Ball Forming for Wire Bonder
Authors: Chen Jau-Liang , Lin Yeh-Chao , Liu Chun-Hsien , Kuo Wen-Chang , Lee Tzung-Ching
Published: February 2021

The shape and size of free-air-ball formation deeply affect the quality of wire bonding. It not only affects the bondability of first bond (ball bond), but also affects the possibility of processing low loop height bonding for thin form packages and high I/O fine pitch packages. Several parameters, such as tail length, spark gap, supplied voltage, current and time of electrical flame-off unit etc., will affect the free-air-ball formation. This paper represents a study of using error-back-propagation neural network method to analyze the effect of each parameter and to predict the final result of the ball forming. From the experiment, it is shown that neural network can not only be used to precisely predict the size of ball formation, but also saves sampling time.
Using Genetic Algorithms to Set Target Values for Engineering Characteristics in the House of Quality
Authors: Brackin Patricia , Colton Jonathan
Published: February 2021

As part of a strategy for obtaining preliminary design specifications from the House of Quality, genetic algorithms were used to generate and optimize preliminary design specifications for an automotive case study. This paper describes the House of Quality for the automotive case study. In addition, the genetic algorithm chosen, the genetic coding, the methods used for mutation and reproduction, and the fitness and penalty functions are descrobed. Methods for determining convergence are examined. Finally, test results show that the genetic algorithm produces reasonable preliminary design specifications.
Task Planning for Product Development by Strategic Scheduling of Design Reviews
Authors: Mori Toshiki , Ishii Kosuke , Kondo Koichi , Ohtomi Koichi
Published: February 2021

This paper proposes a method for modeling and planning design processes. The method should apply to the early stages of development of which the design process is not yet concrete. A matrix-based process model that represents task dependencies provides the input for the optimization of the design process leading to a graph-based process model. The proposed approach uses graph theory for modeling and planning design processes as well as strategic scheduling of design reviews. The proposed algorithm is applicable to large-scale development projects involving numerous tasks and complicated task relationships.

The paper further discusses the application of the planning method to the design of a major device in a satellite as well as the validity of the approach. The example reduced the number of feedback loops and design reviews compared to the solution obtained by conventional planning methods using the design structure matrix.
Activeprocess: A Process-Driven and Agent-Based Approach to Supporting Collaborative Engineering
Authors: Jin Yan , Zhao Li , Raghunath Arun
Published: February 2021

Collaborative engineering involves multiple engineers and managers working together to develop engineering products. As engineering problems become more and more complex, such as the development of a modern automobile, new technologies are demanded to maintain both effectiveness and efficiency of collaborative engineering. While process models and technologies have been developed to support engineering team work, most of the support remains at project management level. Our research proposes a process-driven and agent-based framework, called ActivePROCESS, to support collaborative engineering. ActivePROCESS is composed of a process model APM that captures both high level and low level activity dependencies, and an agent network that monitors process execution and facilitates coordination among engineers. One important feature of this framework is that the agents can capture emergent dependencies between activities dynamically and provides guidance for coordination by managing and applying the dependencies. In this paper, we first present our process-driven approach to collaborative engineering, and then describe the process model APM and the ActivePROCESS prototype system being developed. We will also describe a case example and discuss several issues experienced from the case study.
A Constraint Network Based System for Integrated Product Development
Authors: Li Yuan , Liou Shuh-Yuan
Published: February 2021

Integrated product development is the future of product development. Integrated product development is a process where both upstream (e.g., functional requirements, styling and cosmetic features, and packaging) and downstream (e.g., manufacturing considerations, testing, dunnage, and disposal) requirements of a product are handled concurrently with its geometry construction. In this research, the so-called ECHO (Engineering Constraint Handling and Optimization) system for integrated product development has been developed. A unique feature of this system is that it can explicitly represent and process both the upstream and downstream requirements. These requirements are represented in the form of constraint networks, rule networks, and assessment matrices. By solving for all of the feasible solutions, the ECHO system instructs the geometry construction, and thus ensures that both upstream and downstream requirements are reflected in the design. A case study for automotive piston development has been implemented to illustrate the capability and use of the ECHO system.
From NURBS to C-NURBS: I — C-NURBS Curves and Their Properties
Authors: Wen Manhong , Ting Kwun-Lon
Published: February 2021

This paper develops a new free-form model, called c-NURBS, which is a general model of NURBS. A c-NURBS curve or surface is the projection of a 6D B-spline curve from a 6D homogeneous space H6 into a 3D space R3. The construction procedure of a c-NURBS curve or surface is that using cubic curves or bicubic patches repeatedly and piecewisely interpolates the given control points. The distinct properties of c-NURBS include independent weight modification, super-convexity, strong c-convex hull, and hidden degrees and control points. These properties greatly enhance the shape control and modification capability. All techniques developed for NURBS, such as the de Boor-Cox algorithm, knot insertion, and degree elevation and reduction, can be applied to c-NURBS. The implementation of c-NURBS requires little improvement on the CAD/CAM systems based on NURBS.
From NURBS to C-NURBS: II — C-NURBS Surfaces and C-Bezier Triangles
Authors: Wen Manhong , Ting Kwun-Lon
Published: February 2021

This paper develops c-NURBS surfaces and c-Bezier triangles. The projection from 6D homogenous space to 3D vector space developed in previous papers [12, 13] is applied to surfaces. As a result, a c-NURBS surface can be constructed using bicubic patches to interpolate the given control points with the de Boor-Cox algorithm. Based on this, c-NURBS surfaces have the properties of independent weight modification, super-convexity, strong c-convex hull, and hidden degrees and control points. A c-Bezier triangle can be constructed using cubic patches to interpolate the given control points with the de Casteljau algorithm. Based on this, the c-Bezier triangle has the properties of independent weight modification, super-convexity, and hidden degrees and control points. These properties provide great convenience for shape control and modification operations.
Development of a Voronoi Tree for Cavities by Hodograph-Hodograph Intersection
Authors: Vinnakota Ravi , Butler Alley , LeClair Steven
Published: February 2021

This paper reports on research efforts to efficiently find a Voronoi tree for cavities described by Non-Uniform Non-Rational B-Spline Curves. It examines the motivation for solving this problem, and it reviews the literature on splines and their hodographs (or offset curves). This paper then offers a technique for finding a Voronoi tree for cavities by intersecting hodograph curves. The possibilities for an analytical determination of intersection are considered, and a numerical methodology is presented. This numerical method is demonstrated on two different types of problems: a symmetric cavity problem and an asymmetric cavity problem. Finally, conclusions are drawn about this work.
Systematic Derivation of a Standard Set of Declarative Constraints for Shape Definition in CAD
Authors: Bettig Bernie , Shah Jami
Published: February 2021

This paper describes the derivation of a consistent and comprehensive set of geometrical constraints for shape definition in Computer-Aided Design. These are needed to enable compatibility in parametric data exchange and to promote both standard capabilities and predictable solutions from constraint solving software kernels. The paper look at the mathematical basis for constraints present in the literature and elaborates about all types of constraints that can be described by the same mathematical basis. The approach considers all combinations of distance and angle constraints, on one point or all points of curves and surfaces, as well as transformations and mappings that are required in mechanical design.
Solving Branching Problems for Surface Reconstruction From Free-Form Contours
Authors: Jeong Jaehun , Kim Kwangsoo , Park Hyungjun
Published: February 2021

The 3D shape reconstruction of an object from its 2D cross-sections is important for reproducing it by NC machining or rapid prototyping. Although several different reconstruction methods have been proposed, most of them have allowed only simple branching, or have had difficulty in handling complex branching structures. In this paper, we present a new method for solving branching problems for reconstructing surfaces from a set of free-form contours in planar cross-sections. In this method, we decompose each multiple branching region into a set of single branching regions by providing a set of intermediary contours using modified distance maps. Then, each pair of contours in the single branching regions is linked with triangular facets. An experimental result is given to show that our method gives reasonably good solutions for the representation of complex-shaped objects from planar contours.
Shape Optimization for Fluid Flow Problems Using Bézier Curves and Designed Numerical Experiments
Authors: Cholaseuk Dulyachot , Srinivasan Vijay , Modi Vijay
Published: February 2021

Some problems in constrained shape optimization are considered. The goal in our optimization process is to maximize a measure of device performance computed using CAE, with a CAD compatible representation and specified geometric constraints. This approach illustrates several issues in integration of CAD and CAE systems. We test our ideas on idealized internal flow devices where the underlying device physics is governed by either the Laplace or the Navier-Stokes equations. The geometric shape of the device is represented by Bézier curves. Analysis tools such as the grid generator and the fluid flow solver are treated as a black box. The search pattern during the optimization process is suggested by the design of experiment methodology. The proposed framework is tested with one potential flow problem and two laminar flow diffuser problems.
Plastic Mold Base CAD System With Pre-Paired Feature Library
Authors: Yamaguchi Yasushi , Hasegawa Tamotsu
Published: February 2021

A mold base is a set of fixturing components for mounting the mold onto an injection machine. Since the components have been highly standardized, mold base designers usually select components from a catalog and integrate them into complete mold bases. One of our goals is to support this way of a mold base design process. A system can help a designer by generating product data of a mold base from relative positions of components and by rearranging the whole specification of the mold base according to designer’s modification. The system should be so flexible that it can provide operations corresponding to many kinds of components. This is the other goal of our study. The paper proposes a scheme of a mold base CAD system which allows a user to design a mold base in a natural way and has flexibility to handle various kinds of components.

A mold base consists of plates and other kinds of components, e.g., cavity/core inserts, bolts, pins, etc., which are all embedded into the plates with some assembly and machining information. Therefore, a feature of an embedded component such as a bolt screw should have a mate feature in the corresponding component such as a threaded hole in a plate. A pre-paired feature, a key concept proposed in this paper, consists of two features; an intrinsic feature of a component to be embedded and a mate feature to be machined in a corresponding component. A component defined with a set of pre-paired features may have its own shape as well as assembly and machining information. The system based on object-oriented scheme can generate and maintain the product data of a mold base with this kinds of components. We examined mold base components for categorizing their features and made some experiments with a prototype system.
Maintenance and Parts Fabrication by Reverse Engineering
Authors: Metwalli Sayed M. , Radwan M. Alaa E. , Abdel-Wehab Osama , Shalaby Owaise , Moussa Youssria A. , Hosni Yasser A.
Published: February 2021

With the collapse of the Eastern block, once Egypt’s major industry supplier for machinery and spare parts, and the lack of skilled manpower, the Egyptian industry is finding it difficult to maintain its machinery and industrial base and to compete with the much more sophisticated and coordinated industries abroad. The cutoff of supply of maintenance parts from the Eastern Block, prompt the use of modern reverse engineering (RE) methods in the capturing the geometrical configuration and fabrication of rare maintenance parts, in support of the Egyptian Industry. This paper demonstrates, as a proof of concept, the use of the technology of RE in the fabrication of parts. The success of the experiment initiated a much wider application to the technology, that of patterns making in support of the casting industry. This will provide an accurate and expeditious means to properly maintain industrial plants and produce compatible spare pails urgently needed.
Sampling for Free Form Surfaces Inspection Planning
Authors: ElKott Diaa F. , ElMaraghy Hoda A. , Nassef Ashraf O.
Published: February 2021

This paper presents four methodologies for sampling of free form surfaces and discusses their merits and application. These are equi-parametric sampling, patch size based sampling, patch mean Gaussian curvature based sampling, and the combined patch size and patch mean Gaussian curvature based sampling. The locations of points inspected for a NURBS surface are optimized to minimize the maximum deviation between the surface fitted to the data points and the designed surface. During optimization, the inspection process is simulated, a parametric NURBS surface is fitted to the data points and the maximum deviation between the fitted and designed surfaces is minimized. Algorithms for the application of the sampling methodologies were implemented using MATLAB software. Each sampling methodology is explained, and illustrated by an example. The performance of the different sampling methodologies are compared in terms of the maximum deviation obtained and the CPU time needed to accomplish the sampling task.
Design of C-Frames Using Real-Coded Genetic Optimization Algorithms and NURBS
Authors: Nassef Ashraf O. , Hegazi Hesham A. , Metwalli Sayed M.
Published: February 2021

C-frames constitute a large portion of machine tools that are currently used in industry. Examples of these frames include drilling machines, presses, punching and stamping machines, clamps, hooks, etc. The design parameters of these frames include the dimensions of their cross-sections, which should be chosen to withstand the applied loads and minimize the element’s overall weight. Traditionally, the cross-section of C-frame belonged to a set of primitive shapes, which included I, T, trapezoidal and rectangular sections. This paper introduces a new methodology for designing the frame’s cross-section. The cross-sectional shape is represented using non-uniform rational B-Spline (NURBS) in order to give it a form of shape flexibility. A special form of genetic algorithms known as real-coded genetic algorithms is used to conduct the search for the design objectives. Real-coded genetic algorithms are known to outperform the simple binary representation genetic algorithms when dealing with continuous search spaces. The results showed that the optimal shape was a semi I/T-section with the material bulk related to the applied load.
Topology Synthesis of Large-Displacement Compliant Mechanisms
Authors: Pedersen Claus B. W. , Buhl Thomas , Sigmund Ole
Published: February 2021

This paper describes the use of topology optimization as a synthesis tool for the design of large-displacement compliant mechanisms. An objective function for the synthesis of large-displacement mechanisms is proposed together with a formulation for synthesis of path-generating compliant mechanisms. The responses of the compliant mechanisms are modelled using a Total Lagrangian finite element formulation, the sensitivity analysis is performed using the adjoint method and the optimization problem is solved using the Method of Moving Asymptotes. Procedures to circumvent some numerical problems are discussed.
Virtual Prototyping-Based Optimal Design of Multiple Function Panels for a New PEM Fuel Cell Stack
Authors: Wang Gaofeng Gary , Dong Zuomin
Published: February 2021

At present the optimal design of a complex mechanical component, assembly and system is often carried out using overly simplified and less reliable mathematical models. In addition, many costly and time-consuming physical prototypes have to be developed to improve an industrial design through a lengthy trial-and-error process. In this work, a global optimal design method based on the parametric virtual prototypes of a mechanical design is proposed. The optimal design of multiple functional panels of a Proton Exchange Membrane (PEM) fuel cell stack is used to illustrate the approach. An efficient global optimization search technique, the adaptive response surface method, is applied in the design.
A Coordination-Based Approach to Robust Product Design
Authors: Chen Li
Published: February 2021

Robust product design is a two-objective optimization problem in nature. On the one hand, it is wished to minimize variations in product performance (i.e. first goal); on the other hand, it is desired to maximize product functionality (i.e. second goal). As known, these design goals may not arrive at their own optima at the same time; therefore, coordination between the two perfonning goals is needed during the design iterations to help achieve high robustness in product performance in the sense that a best compromise design is reached. In this work, a coordination-based robust design approach is developed to control the computational aspect of robust design process in a coordinated fashion, allowing that high-quality engineered products are produced with designing-in of performance precision and accuracy through robust design. A fuzzy control algorithm in terms of coordination rules prescribed is generated for handling design coordination by tuning an adaptive design parameter β, defined over the domain from 0 to 1.0. Three coordinated design models are discussed along with the study of a design example.
Layout of an Automobile Transmission Using Three-Dimensional Shapeable Components
Authors: Yin Su , Cagan Jonathan , Hodges Peter , Li Xianren
Published: February 2021

An extended pattern search algorithm is presented for the placement of shapeable components within a product layout. The algorithm is applied to an automobile transmission layout taking into account the shapeability of the components. Overlap between components is allowed and penalized during the optimization process. Shapeable octrees are used to evaluate the amount of overlap between pairs of components. The algorithm minimizes the connection cost in addition to optimizing the position and size of the components. A shapeable component has a defined geometry, but its size may vary within limits. The size of clutches in a transmission is determined by the torque capacity requirement, thermal requirement, and gain requirement. Under a given load, the size of a clutch satisfying a set of functional requirements is related to its location in the transmission assembly, making it necessary to design the clutches on the fly while laying out the components.
Local Approximation of the Efficient Frontier in Robust Design
Authors: Zhang Jinhuan , Wiecek Margaret M. , Chen Wei
Published: February 2021

The multiple quality aspects of robust design have brought more and more attention in the advancement of robust design methods. Neither the Taguchi’s signal-to-noise ratio nor the weighted-sum method is adequate in addressing designer’s preference in making tradeoffs between the mean and variance attributes. An interactive multiobjective robust design procedure that follows upon the developments on relating utility function optimization to a multiobjective programming method has been proposed by the authors. This paper is an extension of our previous work on this topic. It presents a formal procedure for deriving a quadratic utility function at a candidate solution as an approximation of the efficient frontier to explore alternative robust design solutions. The proposed procedure is investigated at different locations of candidate solutions, with different ranges of interest, and for efficient frontiers with both convex and nonconvex behaviors. This quadratic utility function provides a decision maker with new information regarding how to choose a most preferred Pareto solution. As an integral part of the interactive robust design procedure, the proposed method assists designers in adjusting the preference structure and exploring alternative efficient robust design solutions. It eliminates the needs of solving the original bi-objective optimization problem repeatedly using new preference structures, which is often a computationally expensive task for problems in a complex domain. Though demonstrated for robust design problems, the principle is also applicable to any bi-objective optimization problems.
Automatic Set-up and Fixture Planning for 3-Axis Milling
Authors: Echave Javier , Shah Jami J.
Published: February 2021

This paper presents a pragmatic approach for automating set-up and fixture planning for 3-axis machining on CNC machines. Although the larger project encompasses automation and integration of all aspects of machining feature recognition, tolerance charting, high level (macro) planning, and detailed (micro) planning, this paper focuses only on set-up and fixture planning. Only standard modular fixtures are considered (tooling plates, rest pads, pin locators, strap clamps, and vises). In set-up planning we consider not only similar tool approach directions and processes for feature grouping, but also spatial constraints in machines, tools and fixtures. The approach presented here for fixture planning combines elements of both geometric reasoning and feature-based approaches. Set-ups are automatically planned based on the volumes to be removed in each workpiece orientation and the instantaneous state of the stock is tracked at the different stages of the proposed plan. Also verification techniques use feature information to estimate possible collisions between fixtures and volumes to be removed. The fixture planning algorithm is based on both the 3-2-1 locating principle and Vise clamping methods. The overall system architecture is modular, allowing the possibility of selective use of the modules by other developers of CAPP systems. The process planning system exploits the capabilities of commercial toolkits for geometric modeling (ACIS) and NC toolpath generation (STRATA).
Multiobjective Optimization by Iterative Genetic Algorithm
Authors: Grignon Pierre M. , Fadel Georges M.
Published: February 2021

This paper presents a method to simultaneously produce multiple solutions to unconstrained multi-objective optimization problems. The proposed methodology uses populations of sets instead of populations of individuals and iterative calls to a Genetic Algorithm (IGA) to obtain a set of solutions spread across the Pareto set in the objective space. The superiority of such an approach to single run, conventional population Pareto GAs is shown. The various difficulties of the algorithm and the methods used to overcome them are detailed. Finally, the paper expands upon how this method can be used with or without user inputs, and shows an analysis of its performance by applying it to a succession of increasingly difficult problems, identifying its range of application.
Robustness Evaluation of a Miniaturized Machine Tool
Authors: Mishima Nozomu , Ishii Kousuke
Published: February 2021

This paper applies the method of robust design to machine tool design. The new design focuses on miniaturization that provides significant for energy and space saving. Our approach combines an analytical procedure representing the machining motions of a machine tool (form-shaping theory) with procedures for robust design. The effort identifies the design parameters of a machine tool that significantly influence the machining tolerance and leads to a general design guidelines for robust miniaturization. Further, this research applies the Taguchi method to the form-shaping function of a prototype miniature lathe. The analysis addresses five machine tool dimensions as control factors, while treating local errors in the machine structure as noise factors. The robustness study seeks to identify the importance of each factor in improving performance of the machine tool. The result shows that the thickness of the feed drive unit affects the performance most significantly. Among the local errors, straightness error of the same feed drive unit has a critical importance.
Comparison of Two Multiobjective Optimization Techniques With and Within Genetic Algorithms
Authors: Azar Shapour , Reynolds Brian J. , Narayanan Sanjay
Published: February 2021

Engineering decision making involving multiple competing objectives relies on choosing a design solution from an optimal set of solutions. This optimal set of solutions, referred to as the Pareto set, represents the tradeoffs that exist between the competing objectives for different design solutions. Generation of this Pareto set is the main focus of multiple objective optimization. There are many methods to solve this type of problem. Some of these methods generate solutions that cannot be applied to problems with a combination of discrete and continuous variables. Often such solutions are obtained by an optimization technique that can only guarantee local Pareto solutions or is applied to convex problems. The main focus of this paper is to demonstrate two methods of using genetic algorithms to overcome these problems. The first method uses a genetic algorithm with some external modifications to handle multiple objective optimization, while the second method operates within the genetic algorithm with some significant internal modifications. The fact that the first method operates with the genetic algorithm and the second method within the genetic algorithm is the main difference between these two techniques. Each method has its strengths and weaknesses, and it is the objective of this paper to compare and contrast the two methods quantitatively as well as qualitatively. Two multiobjective design optimization examples are used for the purpose of this comparison.
An Extension of the Orthogonal Packing Problem Through Dimensional Flexibility
Authors: Callaghan Alison R. , Nair Anoop R. , Lewis Kemper E.
Published: February 2021

This paper presents a new approach to solving the orthogonal packing problem (OPP). The OPP is shown to be related to one class of resource allocation problems, namely the land allocation problem. The proposed method differs from traditional methods in that component dimensions are not prescribed, allowing designers greater flexibility and giving them the ability to choose from a number of different solutions. We will show that in removing constraints from dimensions, we allow for the possibility for finding better solutions and this is verified in the case study.
A Numerical Study of Crash Optimization
Authors: Yang R. J. , Tho C. H. , Wu C. C. , Johnson D. , Cheng J.
Published: February 2021

In this paper, numerical crash optimization was performed and studied. Three design optimization approaches: gradient-based, DOE/Penalty/Gradient-based, and DOE/Penalty/Response Surface Method, were employed to solve a front rail crash optimization problem using two single-objective formulations. An in-house explicit code FCRASH was used for solving the nonlinear, transient crash problem. The optimization process was carried out using a commercial software package, iSIGHT from Engineous Software Inc. A front rail crash model was used as the benchmark to demonstrate those approaches. Based on the numerical experiments, a simple, viable, and relatively efficient approach is proposed.
Design of Compliant Mechanisms for Amplification of Induced Strain Actuators
Authors: Canfield Shawn , Frecker Mary I.
Published: February 2021

The focus of this paper is on designing compliant mechanism amplifiers for piezoelectric actuators using a topology optimization approach. Two optimization formulations are developed: one in which the overall stroke amplification or geometric advantage (GA) is maximized, and another where the mechanical efficiency (ME) of the amplifier is maximized. Two solution strategies are used, Sequential Linear Programming (SLP) and an Optimality Criteria method, and results are compared with respect to computation time and mechanism performance. Design examples illustrate the characteristics of both problem formulations, and physical prototypes have been fabricated as proof of concept. An automated detail design procedure has also been developed which allows the topology optimization results obtained in MATLAB to be directly translated into a neutral 3-D solid geometry format for import into other CAE programs.
Robust Design: Goal Formulations and a Comparison of Metamodeling Methods
Authors: Lin Yao , Krishnapur Kiran , Allen Janet K. , Mistree Farrokh
Published: February 2021

In this paper, through theoretical analysis, we point out the limitations of goal formulations in previous methods for approximation-based robust design. Based on different philosophies and mathematical deduction, we propose three new methods to formulate robust design goals. Using a single variable function, we compare and contrast the use of response surface models and kriging models for approximating non-random, deterministic computer analyses in robust design with large variances of design variables in a highly nonlinear design space. Our preliminary conclusions are: 1) kriging models perform better than response surface models in a large design space with a high degree of nonlinearity, and 2) more robust solutions are achievable with kriging models than with response surface models.
The General Optimization of Cylindrical Gears Including Robustness
Authors: Houser Donald R. , Luscher Anthony F. , Regalado Isaias
Published: February 2021

The optimum solution for a gear design depends upon the optimization criteria used; also, the performance of the optimum may be affected due to variations in the operating conditions or the existence of manufacturing errors. In order to minimize the effects of these variations, it is necessary to perform a robustness analysis during the design process. This paper discuss the development of a procedure for the robust optimization of gears considering multiple objectives, as well as a preliminary exploration of the design space and a sensitivity analysis to manufacturing errors for a particular example of spur and helical gears.
Assessing Value for Product Family Design and Selection
Authors: Gonzalez-Zugasti Javier P. , Otto Kevin N. , Baker John D.
Published: February 2021

A platform is the set of elements and interfaces that are common to a family of products. We have previously presented a method for designing product families based on platforms that quantifies performance and cost metrics. That approach allows a team of engineers to design and evaluate candidate platforms, given perfect understanding of the designs and requirements. In this paper we present a model to account for uncertainty present during the development of those product families. Real options concepts are introduced to model the risks and delayed decision benefits present under uncertainty in technologies, funding, etc. We develop a quantitative measure of the value to the company for different family designs, and apply it to select the most appropriate design from the possible alternatives. An application to the design of platform-based families of spacecraft is shown. Results from the models indicated the platforms that were most valuable to the company under different scenarios, as well as the sensitivity of the value of each design to different uncertainty factors.
Sensitivity Analysis for Non-Linear Structures
Authors: Kong Qiang , Gea Hae Chang
Published: February 2021

In this paper, sensitivity analysis of total strain energy for nonlinear structures is studied. Based upon the law of energy-consistent, effective stress and strain are defined. The total strain energy is transformed in the form of the effective strain and stress. A closed-form approach for sensitivity calculation is derived. This method can also be extended to large displacement, large rotation problems using the 2nd Piola-Kirchhoff stress and Green-Lagrange stress. Numerical results from the proposed method are compared with those from finite differencing method.
A Neural Network-Based Prediction of the Weld Lines in Resin Transfer Molded Parts
Authors: Soltani Faezeh , Manoochehri Souran
Published: February 2021

A model is developed to predict the weld lines in Resin Transfer Molding (RTM) process. In this model, the preforms are assumed to be thin flat with isotropic and orthotropic permeabilities. The position of the weld lines formed by multiple specified inlet ports are predicted using a neural network-based back propagation algorithm. The neural network was trained with data obtained from simulation and actual molding experimentation. Part geometry is decomposed into smaller sections based on the position of the weld lines. The variety of preforms and processing conditions are used to verify the model. Applying the neural networks reduced the amount of computational time by several orders of magnitude compared with simulations. The models developed in this study can be effectively utilized in iterative optimization methods where use of numerical simulation models is cumbersome.
A VR Based 3D Graphics User Interface for CAD Modeling System
Authors: Zheng J. M. , Chan K. W. , Gibson I.
Published: February 2021

With the advancement of computer techniques, a greater emphasis has been placed on intuitive human-computer interactions (HCIs). Virtual Reality systems can offer a novel way for users to interact with the objects in the computer generated environment (the so called Virtual Environment, VE). Through VR technology, we have the ability to replace the traditional input device, such as keyboard and mouse, with other modes such as speech and gesture.

In our research project, we use a CyberGlove, developed by Virtual Technology Inc., as an input device to develop a desktop CAD modeling system for conceptual designers. We elaborate the limitations of the Dataglove and use gestures to support intuitive human-computer interface. To develop this gesture interface, we emphasize that conceptual designers are allowed full-freedom to use different kinds of gestures to conduct various geometric shape operations instead of depending solely on keyboard and 2D mouse. The designers can indicate objects or directions simply by pointing with the hand, and manipulate the position and orientation of an object by grasping and turning. The “virtual tools” can be used for shaping, cutting, and joining objects. We employ the 3D GUIs for enhancing the gesture interface. In the VE, the 3D menu and “virtual hand” float over the objects rather than being part of the scene. Various 3D cursors can be used to select menu or manipulate the object.
Computer Aided Design of Piezoelectric/Elastic Trimorph Ring Actuator
Authors: Chang Shuo-Hung , Lin Jann-Fang
Published: February 2021

The Kirchoff-Love plate theory and electroelasticity theory are combined to formulate the computer aided design model for the trimorph ring actuators. An isotropic elastic ring is laminated between two identical piezoelectric rings to form the trimorph actuator. The inner surface of the actuator is fixed, and the outer surface is free or transversely load. The analytical solutions for the transverse displacement and the force distribution are derived. Numerical simulations for the transverse displacement under free and loaded boundary conditions are conducted. The maximum transverse displacements as functions of the geometry variables such as the thickness ratio and radius ratio are calculated and presented.
A Knowledge Base Approach for Tolerancing in Computer-Aided Process Planning
Authors: Tsai Jhy-Cherng , Tsai Weirong
Published: February 2021

This paper presents a knowledge-base approach that assists a designer to evaluate possible process plans and associated costs based on tolerancing specifications of the designed part. It is an effort to take dimensional tolerances into computer-aided process planning (CAPP) for cylindrical parts through the usage of databases and knowledge bases. Geometric features with tolerancing specifications in a CAD system are first used to determine possible machining operations that can achieve the specified tolerances based on data from the machining feature database, the process precision grade database, and the precision grade database. Process plans are then generated based on rules and knowledge from process sequence knowledge base and the machining feature database. Possible process plans are further organized as a graph. Optimal process plan with least cost is then selected by searching through the graph. This is achieved based on machine set-up and operation costs that are derived from the machine tool resource database, the process parameter database, and the machine set-up and operation cost database. A CAPP software prototype supporting tolerance design on the AutoCAD platform is also demonstrated with examples to illustrate this approach.