bluuebunny/crossref_metadata_2025 huggingface dataset:
Further Studies of General Shells by Hybrid Strain Based Triangular Elements
Authors: Liu Meilan L. , To Cho W. S.
Published: February 2021

This paper presents a further study of various lower-order flat triangular shell elements that were based on the Hellinger-Reissner hybrid strain formulation and were developed previously by the authors. The present investigation is to examine the effects of including membrane-bending coupling feature in the shell element formulation on the performance of the lower-order shell elements. Several features are considered. These are, for example, the membrane-bending coupling, tue linear distribution of the assumed strain field of the membrane strain, and the hybrid strain formulation with linear assumed membrane strains and membrane-bending coupling. A study on mesh topology is also included. This relatively detailed study leads one to the conclusion that the hybrid strain based flat triangular shell elements previously developed by the authors are attractive and promising for economical analysis of general shells. It is also found that the inclusion of features such as membrane-bending coupling is unnecessary. Numerical results presented here seem to strongly substantiate the theoretical developments that flat triangular shell elements do converge to the correct solution of deep shell theory. Finally it is observed that for deep shell problems appropriate mesh topology becomes the key to an accurate finite element solution.
On Simultaneous Triangularization of the Coefficients of Linear Systems
Authors: Lee W. C. , Ma F.
Published: February 2021

The coefficients of a linear nonconservative system are arbitrary matrices lacking the usual properties of symmetry and definiteness. An efficient way for the analysis of a nonconservative system is to reduce its coefficient matrices simultaneously to upper triangular forms. The purpose of this paper is to present some criteria for simultaneous triangularization and, when applicable, to expound a constructive procedure for triangularization.
A Combined Analytical and Numerical Approach for the Solution of an Edge Loaded Semi-Infinite Elastic Sheet
Authors: Sun Xin , Karr Dale G. , Han Chunhui
Published: February 2021

Edge loading of an semi-infinite elastic sheet is of interest to many engineering applications. In this paper the penetration problem involving a rigid indentor and an elastic semi-infinite sheet of uniform thickness is addressed using a combined analytical and numerical approach. The tenth-order approximate theory of stretching of an isotropic sheet is applied to formulate the governing differential equations. Solutions are then obtained using Fourier transforms for various loading conditions and numerical schemes are employed to calculate the three dimensional state of stress throughout the sheet. The influence of the aspect ratio on the resulting stress state is studied. Limit solutions for thin sheet and thick sheet are presented. Finite element analyses of the same loading conditions are also performed. Results are compared with those of the tenth-order theory and the stress distribution assumptions of the tenth-order theory are examined.
Modal Sensitivity Analysis of Coupled Acoustic-Structural Systems
Authors: Luo Jian Hui , Gea Hae Chang
Published: February 2021

Modal analysis of coupled acoustic-structural systems leads to unsymmetric eigenproblem of special form which introduce different left and right eigenvectors. In this paper, the relation between left and right eigenvectors is first established by symmetrization of the unsymmetric eigensystem, and then Nelson’s method is extended to coupled acoustic-structural systems for calculating the sensitivities of the eigenvalues and eigenvectors. The method only needs to calculate the sensitivities of the right eigenvectors and can treat Helmholtz resonance mode naturally. The procedure is verified to be accurate and effective by applying to an acoustic-box model.
Free External Tube Inversion Simulation Using FEM
Authors: Çolakoğlu Ali , Yıldırım R. O. , Kaftanoğlu B.
Published: February 2021

In this work the finite element method is employed to investigate the free external tube inversion. At the same time, quasi-static tests on cold drawn seamless mild steel tubes (BS 3602-CFS 360) with 50.8 mm (2 in) outside diameter, 1.6 mm (0.064 in) wall thickness and 203.2 mm (8 in) length are performed. The energy absorption capacities and steady-state inversion loads are observed. The finite element predictions are compared with a typical experimental result.
Midsurface Abstraction From 3D Solid Models for Engineering Analysis
Authors: Rezayat Mohsen
Published: February 2021

An integral part of implementing parallel product and process designs is simulation through numerical analysis. This simulation-driven design requires discretization of the 3D part in an appropriate manner. If the part is thin or has thin sections (e.g., plastic parts), then an analysis model with reduced dimensionality may be more accurate and economical than a standard 3D model. In addition, substantial simplification of some details in the design geometry may be beneficial and desirable in the analysis model. Unfortunately, the majority of CAD systems do not provide the means for abstraction of appropriate analysis models. In this paper we present a new approach, based on midsurface abstraction, which holds significant promise in simplifying simulation-driven design. The method is user-friendly because very little interaction is required to guide the software in its automatic creation of the desired analysis model. It is also robust because it handles typical parts with complex and interacting features. Application of the method for feature recognition and abstraction is also briefly discussed.
Knowledge-Based Integrated Manufacturing Flexible Simulation System
Authors: Dong Ming , Cha Jianzhong , E Mingcheng
Published: February 2021

In this paper, we present a knowledge-based flexible simulation system for integrated manufacturing. The simulation model knowledge base of a CIMS is constituted of five parts: FBS models of the CIM-OSA system architecture, entity classes library, procedural knowledge base, database and inference engines. The knowledge-based simulation models are represented by the object-oriented frame language and their behaviours are generated by inference engines reasoning about the sets of procedural rules. Because of the use of various classes libraries which make this system flexible, we call it a knowledge-based integrated manufacturing flexible simulation system.
An Efficient Parallel Algorithm for Rectangular Packing Based on Bintree Expression
Authors: Wang Aihu , Cha Jianzhong , Wang Jinmin
Published: February 2021

In this paper, a method using bintree structure to express the states of the packing space of rectangular packing is proposed. Through the sequential decomposition of the packing space, the optimal packing scheme of various sized rectangular packing can be obtained by every time putting the optimal piece that satisfies specular conditions toward the current packing space and by locating it at the up-left corner of the current packing space. Different optimal packing schemes that satisfy different demands can be obtained by adjusting the values of the ordering factors KA and KB. A parallel algorithm based on SIMD-CREW shared-memory computer is designed through the analysis of the parallelism of the bintree expression. The whole packing process is clearly expressed by the bintree. The computational complexity of the algorithm is shown to be O(n2logn). Both the experimental results and the comparison with other sequential packing algorithms have proved that the parallel packing algorithm is efficient. What is more, it nearly doubles the problem solving speed.
A Primal-Dual Interior-Point QP Method and its Extension for Engineering Optimization
Authors: Zhang Xiong , Zhou Ji , Yu Jun , Cao Ju
Published: February 2021

Presented in this paper is a primal-dual infeasible-interior-point quadratic programming (QP) algorithm and its extension for nonlinear programming that is suited for engineering design and structural optimization, where the number of variables are very large and function evaluations are computationally expensive. The computational experience in solving both test problems and optimal structural design problems using the algorithm demonstrated that the algorithm finds an approximate optimal solution in fewer iterations and function evaluations, the obtained solution usually is an interior feasible solution, and so the resulting method is very efficient and effective.
Experimental Study of a Variable Pressure Damper on Automotive Valve Motion
Authors: Liou Jin-Jang , Huang Grodrue , Hsu Wensyang
Published: February 2021

A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined.

Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.
Flexible Optimization of Machine Products Considering the Working Environment
Authors: Yoshimura Masataka , Nishikawa Takatoshi
Published: February 2021

In order to obtain product designs which enhance the flexibility for change in the working environment of the product, a flexible design optimization method is proposed in which any change is clearly evaluated at the design stage. Here, a criterion of maximization of the flexibility for the product working environment is added to the conventional criteria such as the product performance and the manufacturing cost and a multiobjective optimization problem is formulated. The influence that enhancing flexibility has on the other characteristics is integratedly evaluated by the tradeoff analysis of the Pareto optimum solution set. Then, the preference structure of the decision maker is formulated by the preference function for each evaluative characteristic. The preference functions are interactively modified based on the tradeoff analysis between the evaluative characteristics. The solution most sufficiently reflecting the preference structure of the decision maker is finally determined as the design solution.
A Cubic Spline Algorithm on the Rotation Group Using Cayley Parameters
Authors: Park F. C. , Kang I. G.
Published: February 2021

This article presents a cubic spline algorithm for interpolation on the rotation group SO(3). Given an ordered set of rotation matrices and knot times, the algorithm generates a twice-differentiable curve on SO(3) that interpolates the given rotation matrices at their specified times. In our approach SO(3) is locally parametrized by the Cayley parameters, and the generated curve is cubic in the sense that the Cayley parameter representation is a cubic polynomial. The resulting algorithm is a computationally efficient way of generating bi-invariant (i.e., invariant with respect to choice of both inertial and body-fixed frames) trajectories on the rotation group that does not require the evaluation of transcendental functions, and can also be viewed as an approximation to a minimum angular acceleration trajectory. Because the Cayley parameters provide a one-to-one correspondence between R3 and a dense set of SO(3), the resulting trajectories do not have the “multiple winding” effect that occurs in several existing methods.
Development of CAD System for the Fabrication of LCD/VFD Mask From 2D CAD Data
Authors: Jung Seungwook , Lee Kunwoo , Kim Hoisub
Published: February 2021

In the industry of manufacturing photo mask of Liquid Crystal Display (LCD) or Vacuum Florescent Display (VFD), there have been strong needs for a CAD system of fabricating a pattern mask directly from the CAD data of 2D mask design. This paper presents brief introductions to several algorithms and implementations used in the development of a CAD system for LCD/VFD mask fabrication. For the laser writer, it is simply required to provide the loop information of the pattern shapes. The ray casting algorithm is applied to derive this loop information from the CAD data composed of random vector list. For the photo plotter, the selection of the proper apertures and their plotting paths are derived to expose exact pattern shapes in the shortest time. The idea of Voronoi diagram is used to efficiently obtain an exact aperture path in this study. This paper also features some ideas for automatically detecting and fixing errors of designer’s drawing.
Using Design Capability Indices to Satisfy Ranged Sets of Design Requirements
Authors: Chen Wei , Simpson Timothy W. , Allen Janet K. , Mistree Farrokh
Published: February 2021

For robust design it is desirable to allow the design requirements to vary within a certain range rather than setting point targets. This is particularly important during the early stages of design when little is known about the system and its requirements. Toward this end, design capability indices are developed in this paper to assess the capability of a family of designs, represented by a range of top-level design specifications, to satisfy a ranged set of design requirements. Design capability indices are based on process capability indices from statistical process control and provide a single objective, alternate approach to the use of Taguchi’s signal-to-noise ratio which is often used for robust design. Successful implementation of design capability indices ensures that a family of designs conforms to a given ranged set of design requirements. To demonstrate an application and the usefulness of design capability indices, the design of a solar powered irrigation system is presented. Our focus in this paper is on the development and implementation of design capability indices as an alternate approach to the use of the signal-to-noise ratio and not on the results of the example problem, per se.
Dynamic Simulation for the Structural Integrity of Fluid Filled Thin Walled Tanks Subjected to Impact Loading
Authors: Park S. U. , Gilmore B. J. , Singer R. R.
Published: February 2021

The transport of hazardous materials in truck cargo tanks can cause severe environmental damage as a result of the tank’s failure during a collision. Impact due to collision involves the transient dynamic response of the tank, fluid and their interaction. This paper develops a computational approach to predict the dynamic transient response of the tank shell structure subjected to impact loads during crash accidents. In order to compute the fluid and structure interaction, the finite element formulations for the added mass to the structure are developed and integrated with DYNA3D, the nonlinear dynamic structural finite element code. Thus, the computer based approach provides an efficient design tool for fluid filled thin walled structures in general and cargo tanks subjected to an impact situation. This paper presents the lumping process required by the added mass approach for cargo tanks under impact conditions. The structural integrity performance of cargo tank shell construction is investigated.
Two-Dimensional Packing Problems Using Genetic Algorithms
Authors: Jain Sakait , Gea Hae Chang
Published: February 2021

This paper presents a technique for applying genetic algorithms for the two dimensional packing problem. The approach is applicable to not only convex shaped objects, but, can also accommodate any type of concave and complex shaped objects including objects with holes. In this approach, a new concept of a two dimensional genetic chromosome is introduced. The total layout space is divided into a finite number of cells for mapping it into this 2-D genetic algorithm chromosome. The mutation and crossover operators have been modified and are applied in conjunction with connectivity analysis for the objects to reduce the creation of faulty generations. A new feature has been added to the genetic algorithm(GA) in the form of a new operator called compaction. Several examples of GA based layout are presented.
Design of Multi-Component Structural Systems for Optimal Layout Topology and Joint Locations
Authors: Chickermane Hemant , Gea Hae Chang
Published: February 2021

Structural optimization techniques presently consider the design of only single structural components. However, most real life engineering design problems involve multiple components or structures. It is therefore necessary to have a methodology that can address the design of multi-component systems and generate designs for the optimal layouts of individual structures and locations for interconnections. The interconnections include supports provided by the ground, joints and rigid connections like rivets, bolts, weld between components. While topology optimization of structures has been extensively researched, relatively little work has been done on optimizing the locations of the interconnections. In this research, a method to model and define design domains for the interconnections has been developed. The optimization process redistributes material in the component design domains and locates the connections optimally using an energy criterion. Some practical design examples are used to illustrate the capability of this method.
Dynamic Analysis of Trochoidal-Type Machine
Authors: Li Shuangqing , Shung John B.
Published: February 2021

In a trochoidal-type machine, when the apex seals are replaced by tight running clearances between the rotor and chamber, the friction and wear can be eliminated and thus high efficiency and reliability can be obtained. There are many factors which contribute to the dynamic running clearances. The control of the vibration of the rotor-shaft system is important for the control of the running clearance. This paper studied the dynamics of the rotor-shaft system of a trochoidal-type machine without apex seal. The shaft is lumped as an equivalent system of a mass and a spring. The stiffness of the spring is determined by static equivalence of the two systems. In other words, when the same load is applied, the two systems should have the same displacement. The lumped mass is determined by the dynamic equivalence of the two systems. In other words, the natural frequency of the continuous system with expected mode is equal to the natural frequency of the lumped system. The bearings are modeled as distributed springs and dampers. The coefficients of the springs and dampers are obtained by solving the Reynolds’ equation. The established model can be used to predict the effect of the dynamics of the rotor-shaft system on the running clearances between the rotor and chamber.
Kinematic Sensitivity Analysis of the Spatial Four-Bar Mechanism
Authors: Zou Hong-Liu , Abdel-Malek Karim , Wang Jia-Yi
Published: February 2021

An analytical formulation for computing kinematic sensitivity of the spatial four-bar mechanism is presented. The experimental code developed is used to compute an assembled configuration for the mechanism due to a design variation. The mechanism is modeled into a graph where a body is defined as a node and a kinematic joint is defined as an edge. The spherical joint is cut to convert the model into a spanning tree structure. Cutting an edge introduces the spherical constraint. The variation of this constraint is computed while maintaining the joint-attachment vectors and orientation matrices as variables. The variation of these variables determine the new kinematic design of the system. A recursive formulation is introduced to obtain the state variation of a body in terms of the state variation of a junction body and of the relative coordinates along the chain. The Jacobian matrix is then transformed from Cartesian coordinate space to joint coordinate space using velocity transformation matrices. Kinematic sensitivity analyses due to changing a joint-attachment vector and an orientation are presented.
Design for Manufacturing: Discrete or Continuous Tolerances
Authors: Feng Chang-Xue Jack , Kusiak Andrew
Published: February 2021

Tolerance design provides a common ground for design and manufacturing engineers. It has significant impacts on the quality, cost, and manufacturing lead time of a product. Most of the literature treats tolerances as continuous, thus continuous analytic models of various types are established based upon the discrete tolerances and manufacturing data with the regression method. It’ll be demonstrated in this research that this method will lead to solutions of both mathematical suboptimum and manufacturing infeasibility. This paper proposes using discrete tolerances with an integer programming approach so that solutions of both mathematical optimum and manufacturing feasibility are ensured at the design stage of the product. Numerical examples illustrate the differences between the discrete and continuous tolerance approaches.
The Skew-Symmetric Property of the Newton-Euler Formulation for Constrained Multibody Systems
Authors: Lin Hong-Chin , Lin Tsung-Chieh , Yae KwangHae H.
Published: February 2021

This paper proposes a special form of the recursive Newton-Euler formulation that satisfies the skew-symmetric property, which is a necessary condition to ensure global convergence in a class of regressor-based identification and adaptive control (Slotine, 1987a & 1987b; Craig, 1987). For general multibody systems, such a special form has been developed in a reduced Euler-Lagrange formulation, but not in the Newton-Euler formulation, which has been very popular in the computational analysis of large scale systems. The paper successfully constructs a pair of inertia and Coriolis-centrifugal matrices for a “skew-symmetric” recursive Newton-Euler formulation, which can be used in both dynamics simulations and control applications.
Representation and Mapping of Geometric Dimensions From Design to Manufacturing
Authors: Shah Jami J. , Yan Yong
Published: February 2021

This paper describes the development of a dimension model for use in both design and process planning. The model also facilitates the converting of dimensions and tolerances (D&T) from design models to machining features extracted automatically by feature recognition systems. The model is based on relative degrees of freedom of geometric entities, such as edges and faces of a part. Dimension graphs are created based on the degrees of freedom. The model allows dimension specification, dimension scheme modification, and dimension scheme validation. A methodology to automatically determine the dimensions of machining volumes obtained by volume decomposition is also described.
Hierarchical Solution of Large-Scale Three-Dimensional Topology Optimization Problems
Authors: DeRose Giuseppe C. A. , Díaz Alejandro R.
Published: February 2021

A new solution strategy for topology optimization in 3D elasticity is discussed. This solution strategy uses principles from hierarchical data structures and image analysis to reduce the computational resources necessary to solve large-scale topology optimization problems. The savings in computational resources result from successive use of increasingly detailed hierarchical models starting from a coarse approximation. These models, stored using octree data structures, are used to determine the finite element discretization at a given hierarchy. Through the use of the hierarchical models, large-scale topology optimization problems in 3D elasticity may be solved on desktop workstations.
Parametric Kinematic Tolerance Analysis of Planar Pairs With Multiple Contacts
Authors: Sacks Elisha , Joskowicz Leo
Published: February 2021

We present an efficient algorithm for worst-case limit kinematic tolerance analysis of planar kinematic pairs with multiple contacts. The algorithm extends computer-aided kinematic tolerance analysis from mechanisms in which parts interact through permanent contacts to mechanisms in which different parts or part features interact at different stages of the work cycle. Given a parametric model of a pair and the range of variation of the parameters, it constructs parametric kinematic models for the contacts, computes the configurations in which each contact occurs, and derives the sensitivity of the kinematic variation to the parameters. The algorithm also derives qualitative variations, such as under-cutting, interference, and jamming. We demonstrate the algorithm on a 26 parameter model of a Geneva mechanism.
Feature Based Problems in Inverse Airfoil Design
Authors: Venkataraman P.
Published: February 2021

A new approach to the design of optimal airfoil shapes is presented in the paper. This requires redefinition of airfoil geometry through Bezier parametric curves whose vertices are the design variables of the problem. A basic panel method incorporating an integral boundary layer development model provides the aerodynamic analysis necessary to solve the optimization problems in airfoil shapes. The optimization technique can be easily adapted to solve the inverse design problem of determining the airfoil geometry for a specified pressure distribution. In this paper it is shown how the inverse problem can be further extended to incorporate additional aerodynamic and geometric features that are important in determining useful airfoil shapes.
Incorporating Dimensional Requirements Into Material Selection and Design of Injection Molded Parts
Authors: Beiter Kurt A. , Ishii Kosuke
Published: February 2021

This paper presents a methodology for incorporating part dimensional tolerancing into material selection for engineering thermoplastics. This work builds on the authors’ previous efforts on integration of mechanical performance and manufacturing cost into candidate design selection. The benefit of this approach is the simultaneous consideration of the implications of material selection and part geometry on estimated manufacturing cost during candidate design selection. The research approach uses the Pressure-Volume-Temperature (PVT) method to estimate shrinkage in thermoplastic parts. The authors then present a method for calculating production costs for meeting part tolerance requirements. Example calculations and a computer program illustrate the proposed methodology.
Rational Bézier and B-Spline Ruled Surface Patches
Authors: Ge Q. J. , Kang Donglai
Published: February 2021

This paper presents a geometric method for constructing bounded rational Bézier and B-spline ruled surfaces directly from line-segments. Oriented line-segments in a Euclidean three-space are represented by vectors with four homogeneous components over the ring of dual numbers. Projective algorithms for rational Bézier and B-spline curves are dualized to yield algorithms for rational Bézier and B-spline ruled surfaces.
Identification of the Optimal Product Configuration and Parameters for Improving Manufacturability
Authors: Xue Deyi
Published: February 2021

A global optimization approach for identifying the optimal product configuration and parameters is proposed to improve manufacturability measures including feasibility, cost, and time of production. Different product configurations, including alternative design candidates and production processes, are represented by an AND/OR graph. Product parameters are described by variables including continuous variables, integer variables, Boolean variables, and discrete variables. Two global optimization methods, genetic algorithm and simulated annealing, are employed for identifying the optimal product configuration and parameters. The introduced approach serves as a key component in an integrated concurrent design system. A case study example is given to show how the proposed method is used for solving the engineering problems.
Robust Design Using Second-Order Shape Design Sensitivity Analysis
Authors: Chen Chin-Jung , Choi Kyung K.
Published: February 2021

The performance of high-quality products should be insensitive to environmental disturbances. Traditional design attempts to create quality in design by tightening manufacturing tolerances, which leads to high manufacturing cost. In spite of the apparent high-quality, when environmental variations appear, performance of products can be degraded. A robust design methodology is presented in this research, to produce a high-quality and low-cost product. By considering manufacturing tolerances and environmental disturbances early in the design stage, a robust design can be obtained. Because robust design requirements that involve first-order sensitivity are formulated as an optimization problem, to accurately evaluate gradients of constraints, a reliable second-order shape design sensitivity analysis (DSA) method is used.
Reconstruction of Cross-Sectional Data Using Implicit Solid Modelling
Authors: Lim Chek T. , Ensz Mark T.
Published: February 2021

In this paper, we present a new technique for constructing mathematical representations of solids from cross-sectional data sets. A collection of 2D cross-sections is generated from the sliced data by merging circular primitives using Implicit Solid Modelling (ISM) techniques which approximate Boolean unions. The spatial locations and radii of the circles for each slice are determined through a nonlinear optimization process. The cost function employed in these optimizations is a measure of discrepancies in the distance from points to the boundary of the reconstructed cross-section. The starting configuration of the optimization, (i.e. initial size and location of the primitives) is determined from a 2D Delaunay triangulation of each slice of the data set. A morphing technique utilizing blending functions is applied to merge the implicit functions describing each slice into a 3D solid. The effectiveness of the algorithm is demonstrated through the reconstruction of several sample data sets, including a femur and a vertebra.
Characteristic Measures for the Representation of Manufactured Surface Quality
Authors: Turner Irem Y. , Srinivasan R. S. , Wood Kristin L.
Published: February 2021

In this paper, we investigate four methods that yield mathematical measures to analyze the precision of surfaces of manufactured parts. These four methods, namely the autocorrelation function, the Fourier spectrum, the Karhunen-Loève expansion, and a fractal-wavelet representation, are applied to surfaces produced from grinding processes. The first two methods are standard methods used in the surface analysis literature for qualitative signal characterization. The Karhunen-Loève expansion method, used in various signal processing applications, has never been applied to the field of surface characterization and representation. The fractal-wavelet representation has been previously proposed by the authors; its suitability to generate characteristic measures is investigated in this paper. The existence of characteristic measures of surface precision should aid designers in choosing process and design parameters and in comparing the precision between competing machining processes. The use of such measures is essential in taking a forward step towards integrating the fields of design and manufacturing.
Process Improvements in Fused Deposition of Ceramics (FDC): Progress Towards Structurally Sound Components
Authors: Jamalabad Vikram R. , Agarwala Mukesh K. , Langrana Noshir A. , Danforth Stephen C.
Published: February 2021

Fused Deposition of Ceramics (FDC) is a Solid Freeform Fabrication (SFF) technique under development at Rutgers University. This technique is based on Fused Deposition Modeling (FDM)2, a commercially available SFF technology. Freeform fabrication of ceramic and metal parts is a means of significantly lowering the cost of currently expensive components. The feasibility of Fused Deposition of Ceramics (FDC) has been demonstrated in the recent past. Crucial to the viable fabrication of ceramic components is the elimination of defects in the parts. Apart from some of the usual traits of SFF techniques, some distinct features of FD Processing lead to defects in fabricated parts. The focus of this work is to study and improve the build procedure of FDM, thereby reducing the defects that are associated with FD processing. Predictable errors in the FDC/FDM components need to be consistently eliminated to increase the yield of fully dense, defect free, green parts. Changes in the manufacturing procedure and operation of FDC are shown to reduce these errors. Fully dense green components are further processed to obtain defect free fully dense sintered ceramic parts.
Application of Convex Hull for Tool Interference Avoidance in 5-Axis CNC Machining
Authors: Lee Yuan-Shin , Chang Tien-Chien
Published: February 2021

In this paper, a methodology of applying convex hull property in solving the tool interference problem is presented for 5-axis NC machining of free-form surfaces. Instead of exhausted point-by-point checking for possible tool interference, a quick checking can be done by using the convex hull constructed from the control polygon of free-form surface modeling. Global tool interference in 5-axis NC machining is detected using the convex hull of the free-form surface. A correction method for removing tool interference has also been developed to generate correct tool path for 5-axis NC machining. The inter-surface tool interference can be avoided by using the developed technique.
A Virtual Design of an Airport Inspection System
Authors: Harper E. , Langrana N. , Burdea G.
Published: February 2021

Virtual simulations are becoming increasingly important in many areas of engineering and design. Increased computing power is enabling more realistic interactions as well as more complex simulations. A virtual luggage inspection system has been developed incorporating a realistic suitcase model. The models are obtained from several different methods, demonstrating flexibility. Contact detection has been implemented allowing object interaction and manipulation. Force feedback has been integrated, and a force response scheme developed, enabling grasped objects to be felt and evaluated. A fairly robust virtual system capable of handling several applications is presented.
The Role of Compliance in the Design of MEMS
Authors: Ananthasuresh G. K. , Kota Sridhar
Published: February 2021

A great majority of the available micro devices and systems use compliant (or flexible) structures and mechanisms. This trend in design takes advantage of micromachining techniques while satisfying the constraints imposed by them. By citing relevant literature, this article briefly notes the influence of compliance on the mechanical design and analysis of Micro-Electro-Mechanical Systems (MEMS).
Data Partitioning for Parallel Intersection of Solids
Authors: Hui K. C. , Kan Y. M.
Published: February 2021

Set-theoretic operation in solid modelling is a basis for various applications in design and manufacturing such as interference detection and NC tool path verification. However, evaluating set-theoretic operation is one of the most time consuming process in solid modelling. Considerable amount of time is required for performing boolean operations on complex objects consisting of large amount of geometric data. It is thus desirable to increase the speed of set-theoretic operations in order to widen the scope of applications of solid modelling systems. This paper presents a method for distributing various entities of two solid models in an array of processors for parallel intersection tests in evaluating set-theoretic operations. A recursive spatial subdivision technique is adopted for partitioning and distributing entities for parallel intersection computation. Parallel algorithms are developed for distributing entities among an array of processors which are mapped to a set of 3-D rectangular regions in the object space. Test results on an experimental system implemented on a DECmpp 12QQQ/Sx/8K distributed memory SIMD computer show that the data partitioning and distribution process requires O(N) time on the average, where N is the number of entities involved.
Modeling and NC Programming for Free-Form Surfaces by Haptic Interfaces
Authors: Kanai Satoshi , Takahashi Hidetomo
Published: February 2021

The haptic interfaces were developed and applied to free-form surface CAD/CAM systems to improve the user interaction with geometric models. Two types of haptic interfaces were designed; a passive force feedback device and an active force feedback device. Two application systems were developed with these devices; the surface modeling system by the passive force feedback device, and the NC programming system by the active force feedback device. In the surface modeling system, the operator can generate the surface geometry by cutting the virtual clay model. In the NC programming system, the operator can directly teach the NC program by tracing the model with active force feedback device. The structure, control method, simulation software and representation of the geometric model in these systems are discussed. The performance and operating efficiency and accuracy of the systems are experimentally examined.
A Technique for Planar Contact Recognition in Automatic Assembly Planning
Authors: Golabi Sa’id , Abhary Kazem , Luong Lee H. S.
Published: February 2021

Recognition of all assembly sequences and selection of the most efficient one have been the main concerns of researchers in assembly planning during the last decade. Few of these researchers attempted to automatically generate assembly sequences using the geometric and solid model data of the product. To solve the problem of contact recognition a broad research was conducted to recognise contact between planar, cylindrical and conical faces during this research. This paper explains one of the techniques developed herein to recognise contact between two planar faces. The necessary geometrical data of a solid model has been extracted from AutoCAD. The method includes new approaches for detecting a point within the solid part of a face, and investigating the intersection of two curved edges.
Experiencing Product Realisation on the World Wide Web
Authors: Radcliffe David F.
Published: February 2021

Experiencing the product realisation process through the creation of an artefact is a vital element in the education of engineering designers. Providing such experiences at University can prove problematic. A new approach is described in which mechanical engineering students achieve such experiences through using the World Wide Web (WWW) as a rapid prototyping and production medium. They work in teams to design, develop, prototype and deliver a simple homepage on the WWW on the subject of concurrent engineering. Concurrent engineering principles and practice provide both the subject matter and a means for developing the product on the Web. The exercise is founded on an experiential model of learning and a coherent framework for describing concurrent engineering. Through provision of structured mechanisms for student reflection on their process, the students can demonstrate learning as illustrated in this paper.
Process Metrics for Asynchronous Concurrent Engineering: Communication in an Internet Newsgroup
Authors: Taylor Dean
Published: February 2021

This paper shows how computer mediated communication in a collaborative design process can be characterized and measured. The example data set is a very large Internet newsgroup captured during a sophomore design course. This paper addresses questions relevant to the management of the design process.

Because the entire transaction has been captured, the messages in a newsgroup provide a wealth of information other than the name of the author. This paper attempts to use the topic and the time/date stamp to draw out deeper more subtle relationships.

The weighted communication matrix is developed and a transformation is used to show that communication patterns can be detected. A dual concept, the Affinity Matrix, is presented to show relationships between topics.

The topic space is developed to represent topic duration and participation. This leads to a formal definition of topic robustness.

Communication activity is grouped by Myers-Briggs Personality Type of the participants. Based on analysis of cognitive modes, individuals tending to analytical and invention modes made active use of the newsgroup while individuals tending to affiliation and implementation made low use of the newsgroup.
Integrating Product Design With Manufacturing Process Design Using the Robust Concept Exploration Method
Authors: Peplinski Jesse D. , Allen Janet K. , Mistree Farrokh
Published: February 2021

How can the manufacturability of different product design alternatives be evaluated efficiently during the early stages of concept exploration? The benefits of such integrated product and manufacturing process design are widely recognized and include faster time to market, reduced development costs and production costs, and increased product quality. To reap these benefits fully, however, one must examine product/process trade-offs and cost/schedule/performance trade-offs in the early stages of design. Evaluating production cost and lead time requires detailed simulation or other analysis packages which 1) would be computationally expensive to run for every alternative, and 2) require detailed information that may or may not be available in these early design stages. Our approach is to generate response surfaces that serve as approximations to the analyses packages and use these approximations to identify robust regions of the design space for further exploration. In this paper we present a method for robust product and process exploration and illustrate this method using a simplified example of a machining center processing a single component. We close by discussing the implications of this work for manufacturing outsourcing, designing robust supplier chains, and ultimately designing the manufacturing enterprise itself.
HVAC CAD Layout Tools: A Case Study of University/Industry Collaboration
Authors: Cagan Jonathan , Clark Richard , Dastidar Pratip , Szykman Simon , Weisser Paul
Published: February 2021

An effective partnership between industry and the university resulted in the system of design tools for the layout of HVAC systems presented in this paper and illustrated with the design of a heat pump. The system provides tools to assist in the placement of components and routing of tubes between the components. Traditional tubes, tubes that have minimized length and number of bends, and those that are impossible to route in the traditional manner, are generated. The paper provides insight on both the collaborative research interaction and the resulting set of tools.
The Identification and Use of Key Characteristics in the Product Development Process
Authors: Lee Don J. , Thornton Anna C.
Published: February 2021

The method of “Key Characteristics” (KCs) is gaining popularity in many US companies as a way to focus the organization on important product features that have a significant impact on product and customer requirements. (Lee et al., 1995; Lee and Thornton, 1996) Research was undertaken at several major US corporations to understand the current and best-practice use of key characteristics. The methods in use were found to be lacking in formality and ease of application. Our observations and subsequent research has resulted in the enhanced key characteristic definitions, categorization, prioritization, and identification methodology presented in this paper. Two case studies using an automotive and an aircraft product are used to illustrate the key characteristic identification method. A high risk key characteristic (referred to as “StatKCs” in this paper) identification technique was also developed that establishes a quantitative relationship between customer requirements and manufacturing costs. The methods presented in this paper can be used to support efficient and effective strategic and operational decisions during the product realization process.
Metrics for Assessing Design Freedom and Information Certainty in the Early Stages of Design
Authors: Simpson Timothy W. , Rosen David , Allen Janet K. , Mistree Farrokh
Published: February 2021

Our primary focus in this paper is on open engineering systems which are readily adaptable to changing design requirements. Designing an open engineering system allows a family of products to be developed around a common baseline model. This entails increasing design freedom and design knowledge during the early stages of design. Toward this end, developing ranged sets (as opposed to points sets) of top-level design specifications provides a means to improve system flexibility by increasing design knowledge while maintaining design freedom. Consequently, our secondary focus in this paper is on metrics for assessing the design freedom and information certainty associated with a ranged set of top-level design specifications. As a demonstration, these metrics are applied to an example problem, namely, the conceptual design of a family of aircraft. Our emphasis in this paper is on introducing open engineering systems and metrics for design freedom and information certainty, not on our example, per se.
Catalogue Design of Technical Systems Based on a Resource Exchange Paradigm
Authors: Heinrich Michael , Juengst Werner E.
Published: February 2021

In this paper, we illustrate the use of the resource exchange paradigm for mechanical systems and, through multi-level configuration, for complex systems. To make this paper self-contained, a short introduction to resource-based modelling is included.
A Survey of PDM Implementation Projects in Selected Swedish Industries
Authors: Sellgren Ulf , Hakelius Cecilia
Published: February 2021

Technology and engineering might be characterized as becoming more knowledge-intensive. A huge amount of data is used and produced in most product development projects. Increasing competition requires shorter reaction time to customer demands and a higher level of innovation. Concurrent Engineering (CE) is a strategic response to competition. It has proved to be a powerful approach to integrating engineering activities in product development. However, integration and parallel activities, that is the essence of CE, add complexity to the process. Consequently, information management is recognized as a major component in many CE models.

Product Data Management (PDM) systems are a class of computer based systems that address the need to manage product related information that is mainly formal and computer interpretable. PDM systems are sometimes referred to as CE enablers.

Results from a resent survey of PDM implementation projects in six Swedish industrial companies, with products ranging from telecommunications systems to trucks and medical equipment, indicate the importance of also utilizing the Concurrent Engineering (CE) approach in the process of implementing an enterprise-wide PDM solution.