bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Aided Local Modifications for the Transition From Part Design to Die Design
Authors: Lu Shao-Chiung , Miller R. Allen , Kinzel Gary L.
Published: March 2021

For a consistent die casting product design database, the die geometry should be generated from and be associated with the original part design. However, the original part design must be modified to include several process specific features, e.g. parting line, drafts, and rounds/fillets, before the creation of the die cavity. This paper deals with the incorporation of automatic/semi-automatic geometric modifications with drafts and rounds/fillets in a CAD system to smooth the transition from part design to die design. The underlying physical concerns behind these local geometric modifications are studied. The significant geometric characteristics in determining the appropriate size of drafts and rounds/fillets are then identified and extracted with geometric reasoning methods. This paper also presents the problems should be noted in applying these modifications to a die casting design.
Effective Properties of 3D Laminated Composites for Finite Element Applications
Authors: Alexander Amos , Tzeng Jerome T. , Drysdale William H. , Burns Bruce P.
Published: March 2021

A model has been developed to compute the effective properties for an arbitrarily shaped element with multiple anisotropic material regions. The analysis utilizes a finite element technique to resolve the complexity of three-dimensional layer geometry, anisotropy, ply orientations, and multi-material regions within an element. Accordingly, the model accounts for complex geometries requiring changes in mesh density and/or arbitrarily shaped elements that cannot be readily aligned with the layers of the laminate. Discontinuity due to ply drop-off or layer terminations within an element is also considered. The computed elastic constants are accurate, especially for the transverse shear properties. The analysis is particularly suitable for finite element applications of near-net shaped thick-section structures. A pre-processor was developed incorporating the effective property model to allow for generation of finite element representations for computer codes such as DYNA3D and ABAQUS.
An Efficient Numerical Method for Dynamic Interaction Analysis of High-Speed Shinkansen Vehicles, Rail, and Bridge
Authors: Tanabe Makoto , Wakui Hajime , Matsumoto Nobuyuki
Published: March 2021

This paper describes a finite element formulation to solve for the combined dynamic behavior of Shinkansen (bullet train) vehicles, irregular rails, and bridges. A mechanical model for interactions between a wheel and an irregular rail is discussed. The bridge is modeled by use of various finite elements. An efficient numerical method, based on modal analysis and exact time integration, is described for solving the nonlinear equations of motion of the Shinkansen vehicle and bridge. The convergence of the exact time integration scheme is discussed and compared with a previous numerical time integration scheme.

A finite element computer program has been developed to analyze the dynamic response of Shinkansen vehicles operating at high speed over irregular rails and a bridge. Numerical examples are presented to demonstrate the effectiveness and validity of the present approach.
A General Finite Element Approach for Porous and Non-Porous Metal-Forming Processes
Authors: Sudhakar B. , Jackson John E. , Rule William K. , Haque Imtiaz
Published: March 2021

A rigid-viscoplastic finite element flow formulation based on the Doraivelu et al. constitutive equation for a porous material is presented. The plasticity equations developed were incorporated into a two-dimensional Eulerian-based finite element code, CFORM. The code predicts the principal variables involved in powder metal forging. Numerical tests performed with the simulation of porous and non-porous materials using this formulation showed good agreement with results from other researchers. Results of this study demonstrate the flexibility of this flow formulation approach in simulating forging for both porous and non-porous materials.
3-D Finite Element Modeling and Analysis of an Armored Vehicle Hull With Multiple Access Openings
Authors: Gupta Aaron D. , Santiago Joseph M. , Meyer Christopher
Published: March 2021

A 3-D finite element model of a bare aluminum vehicle hull with multiple access openings for the driver’s hatch, the commander’s cupola, engine access opening, exhaust grills, cargo hatch, as well as rear door cutout, representing the basic hull of the Armored Personnel Carrier (APC) M113A2 was generated using PATRAN 3 pre/post-processor program. Frequencies and modeshapes obtained using the ADINA finite element code were compared with available experimental modal analysis data for the metallic hull.
A Surface Interpolation Scheme Based on the Theory of Conjugate Surfaces
Authors: Chen Chih-Hsin
Published: March 2021

A surface interpolation scheme is described for interpolating an array of knot points and normals. The scheme is based on the generation of interpolation surface patches by envelopment of a moving base plane which is fixed in the end effector of a robot of two revolute pairs and one prismatic pair. The initial values, the control values, and the interpolation functions of the robot motion are discussed. The equations for determining the geometrical values of an interpolation point are derived with the aid of the theory of conjugate surfaces, and are arranged in order of the corresponding algorithm. The continuity between neighboring interpolation surface patches is proved to be C1.5. The feasibility of improving the continuity by adjusting the control values of the robot motion is investigated.
On the Finite Element Solution of Fractional Contact Problems Using Variational Inequalities
Authors: Refaat M. H. , Meguid S. A.
Published: March 2021

This article is devoted to the development and implementation of a variational inequalities approach to treat the general frictional contact problem. Unlike earlier studies which adopt penalty methods, the current investigation uses Quadratic Programming and Lagrange’s multipliers to solve the frictional contact problem and to identify the candidate contact surface. The proposed method avoids the use of user defined penalty parameters, which ultimately govern the convergence and accuracy of the solution. To establish the validity of the method, a number of test cases are examined and compared with existing solutions where penalty methods are employed.
Influence of PVC on the Product Composition of Solid Waste During Thermal Destruction
Authors: Gupta A. K. , Ilanchezhian E. , Keating E. L.
Published: March 2021

Equilibrium thermochemical calculations of a mixture of non-plastic and plastic surrogate solid waste are presented here under conditions of pyrolysis and combustion. The non-plastic waste is assumed to be cellulose while the plastic waste constituents contained the following different kinds of materials: polyethylene, polyvinyl chloride, polystyrene, polypropylene, polyethylene tetraphthalic, nylon, latex in the form of rubber, polyurethane, acetate and cellophane. The cellulose represents organic portion of the waste such as paper and cardboard. The mole fractions of different stable and unstable compounds formed during pyrolysis are significantly affected by the chemical properties of the waste. In general the amount of CO and H2O was found to remain very high at temperatures up to 2000K. while the CO2, H2O and CH4 decreased with the increase in temperature. The general trend with combustion at different mole fractions of oxygen was to achieve an increase of CO2, H2O, NO and NO2 while the concentrations of CH4, H2, CO and HCl showed a systematic decrease. The concentration and amount to different compounds formed were significantly affected with the amount of air and the chemical nature of the waste. The adiabatic flame temperature is significantly affected by the chemical composition of the plastic under conditions of combustion in air. Plastics yield significantly higher temperatures than the mixture of plastic and non-plastic waste. Experimental results showed good trend with the calculated results. Pyrolysis of waste at higher temperatures followed by combustion of resulting gases yield higher flame temperature and provides excess enthalpy of flames. The results show significant effect of controlled combustion on the amount and nature of chemical species formed as well as the subsequent flame temperature. This information can assist in developing strategies in the design and operation of facilities being used for the permanent disposal of wastes containing varying amounts of plastics.
Storage of Spatial Data in Semantic Databases
Authors: Rishe Naphtali , Li Qiang
Published: March 2021

This paper describes how the semantic binary database model [Rishe-92-DDS] and its implementation [Rishe-91-FS] are extended to represent spatial data: functions over multi-dimensional space, e.g. the ocean temperature as a function of the four-dimensional space-time. The implementation, utilizing extended linear quad-trees, is compact in storage and allows efficient resolution of queries.
The Control of Multi-Bending: A Flexible Method to Fabricate Complex Structural Parts
Authors: Luo Jack X. , Stelson Kim A.
Published: March 2021

The CNC multi-axis bending process can achieve high productivity and flexibility over conventional forming processes for fabricating long slender structural components of arbitrary shape. However, generating a CNC program to produce an accurate part shape is currently a laborious procedure involving trial-and-error by the machine operator. A systematic method has been developed to replace the manual control method and increase the dimensional accuracy. The concept of an intrinsic representation from differential geometry is applied as a basis to represent the part shape and develop the process model. The feedback control is derived from two transfer functions that represent the bending and twisting processes. By applying shape errors to the inverse transfer functions, incremental control commands can be determined and used to improve the control performance. Experimental results have demonstrated that shape errors decrease on subsequent iterations.
Orientation and Trajectory Determination for a Robot With a Laser Distance-Meter As End Effector
Authors: Chiang Luciano E. , Stamm Eugenio
Published: March 2021

This paper describes the design and implementation of a robot system with a laser distance-meter as end-effector. Used to determine wear in large mining equipment by measuring the distance to selected target points, this particular configuration poses a special inverse kinematics problem which is solved using a parametric line formulation. The non-linear resulting system of equations is solved by a Newton-Raphson algorithm and thus the correct joint coordinates for any given target point are obtained.
Restructuring Applied Thermodynamics: Exploratory Thermodynamics
Authors: Morse John S.
Published: March 2021

A graphical method is proposed for removing the “drudge work” of looking up property values and solving the conservation equations and second law in an Applied Thermodynamics course. The vehicle used is VisSim simulation software. The method requires the student to perform the thermodynamic analysis and set up the equations, but the computer finds the property values and solves the equations. This concept allows the student to explore various aspects of the topics covered in such a course, including power and refrigeration cycles, mixtures and psychrometrics, and combustion and equilibrium. Substantial design type problems can be solved easily, as can complicated analyses that are too difficult and time consuming for traditional solution methods.
Quantifying the House of Quality for Optimal Product Design
Authors: Locascio Angela , Thurston Deborah L.
Published: March 2021

Manufacturers seek to improve the quality of their products while reducing costs and decreasing production time. In this paper, we describe a ‘design for X’ methodology that addresses multiple issues that contribute to overall product quality. This methodology builds on the popular House of Quality symbolic construct by using customer preferences and a transformation of the customer -engineering relationship matrix to form constraints on the feasible design space. Multiattribute Utility Theory, a decision analysis tool, provides the mathematical basis to model competing design goals simultaneously and to make rational decisions to affect overall design improvement. When coupled with the constraints, this construct completes a mathematical programming model of the concurrent design problem. With an example, we demonstrate how to extract qualitative information from the House of Quality, formulate the model, and solve it to determine the best design — defined as the optimum combination of multiple quality attributes. This methodology provides a formal framework for decision making in design, allowing manufacturers to Design for Quality.
Abstractions, Design Views and Focusing
Authors: Hoover Stephen P. , Rinderle James R.
Published: March 2021

Abstractions serve to reduce the complexity of the design process by providing a simple yet still useful representation of the design. Abstractions change one or all of the focus, resolution and accuracy of the design representation. Focusing abstractions direct the designer’s attention to fundamental relationships amongst design variables and requirements. The process of forming focusing abstractions incorporates the design relations and variables that are of concern to the designer, while mitigating the complexity of the resulting design view for the designer. The complexity is minimized by reducing the number of variables and relations considered simultaneously. This is done in a manner which allows the designer to determine the need for further refinements in configuration, to make parametric decisions, and to identify critical design relationships. The appropriate use of focusing abstractions can improve both the design process and the final design. Several basic approaches to creating focusing abstractions are described and one method, based upon Gröbner Bases, is developed in detail. This method is appropriate for a design object representation consisting of parametric constraints represented as sets of polynomial equations. This approach is demonstrated within the context of a sample electro-mechanical design problem, a cordless screwdriver.
Issues Critical to the Development of Design History, Design Rationale and Design Intent Systems
Authors: Ullman David G.
Published: March 2021

Design is the evolution of information. This evolution usually begins with an ill-defined need for a product and ends with exact specifications for production, use and retirement or recycling. A number of researchers have hypothesized that capture and reuse of this evolving information has potential for improving the design process and the reuse of design information. Published work has used the terms design history, design rationale, design intent and corporate memory to describe the systems that manage the capture, storage and query of the evolving information. The development of these systems depends on attention to 13 outstanding issues identified in this paper.
Performance Representation in Case-Based Design
Authors: Michelena Nestor , Sycara Katia
Published: March 2021

Reuse of prior design experience allows an engineer to save design time, by leveraging off previous work-out solutions, and to avoid repeating past mistakes, by accessing information on manufacturing or field failures. Indexing and retrieving of design cases is efficiently done based on qualitative descriptions of the behavior specification of a device. Qualitative influences has been used for behavior representation and reasoning since they allow behavior decomposition and synthesis of design parts taken from different contexts. Thus, innovative new designs are generated. However, a drawback of this kind of high-level abstractions is that important performance information contained in design specifications is not taken into account. In this article, performance information such as ranges of operation and types of response are added to the qualitative behavior representation. Higher-order behavior representations are also studied. Reasoning mechanisms are accordingly extended for index generation and retrieval of previous designs. As a result of considering performance information, the number of synthesized designs not performing according to specification can be reduced. Analysis and simulation time spent in design verification is, thereby, also reduced.
Creating an Advanced Collaborative Open Resource Network
Authors: Coyne Robert , Finger Susan , Konda Suresh , Monarch Ira , Prinz Friedrich B. , Siewiorek Daniel P. , Subrahmanian Eswaran , Tenenbaum J. Marty , Weber Jay , Cutkosky Mark , Leifer Larry J. , Bajcsy Ruzena , Koivunen Visa , Birmingham William
Published: March 2021

Carnegie Mellon, in collaboration with several other universities and companies, is beginning to develop ACORN, an Advanced Collaborative Open Resource Network. ACORN will provide the infrastructure to create an electronic community which will be able to design and sell engineered products in competitive markets as well as conduct research and development by collaborating through a network. Creating such a community is a task of national proportions and cannot be accomplished by our group alone since the target community encompasses the entire country. We have an unprecedented opportunity to create and experiment with an electronic community which can serve as the model for a larger national community. In this paper, we outline the architecture for an information infrastructure to create and sustain such a community.

This paper is not a standard research paper; it is being published to invite the members of the community to participate in the evolution of the ideas expressed here and to encourage the shared development of the infrastructure necessary to create this network.
KADS: A Knowledge Aided Mechanical Design System
Authors: McVea William Mark , Haghighi Kamyar
Published: March 2021

Design is an inherently iterative process. This paper will present a knowledge based system that reduces this iterative process to a near minimum. To achieve this goal, the Knowledge Aided Design System (KADS) for mechanical components, uses the techniques of heuristically representing design intuition to evaluate conceptual ideas. The implementation of this design methodology represents a fundamentally new approach to assisting a designer. The trend within similar research is to develop each design tool to encompass more functionality. The research presented in this paper develops a morphology of incorporating design heuristics and analysis techniques into a unified working environment.
Propagation of Nonlinearities in the Inertia Matrix of Tracked Vehicles
Authors: Choi J. H. , Shabana A. A. , Wehage Roger A.
Published: March 2021

In this investigation, a procedure is presented for the numerical solution of tracked vehicle dynamics equations of motion. Tracked vehicles can be represented as two kinematically decoupled subsystems. The first is the chassis subsystem which consists of chassis, rollers, idlers, and sprockets. The second is the track subsystem which consists of track links interconnected by revolute joints. While there is dynamic force coupling between these two subsystems, there is no inertia coupling since the kinematic equations of the two subsystems are not coupled. The objective of the procedure developed in this investigation is to take advantage of the fact that in many applications, the shape of the track does not significantly change even though the track links undergo significant configurations changes. In such cases the nonlinearities propagate along the diagonals of a velocity influence coefficient matrix. This matrix is the only source of nonlinearities in the generalized inertia matrix. A permutation matrix is introduced to minimize the number of generalized inertia matrix LU factor evaluations for the track.
Computer-Aided Displacement Analysis of Spatial Mechanisms
Authors: Thompson Sean , Cheng Harry H.
Published: March 2021

Recently, Cheng (1993) introduced the CH programming language. CH is designed to be a superset of ANSI C with all programming features of FORTRAN. Many programming features in CH are specifically designed and implemented for design automation. Handling dual number as a basic built-in data type in the language is one example. Formulas with dual numbers can be translated into CH programming statements as easily as formulas with real and complex numbers. In this paper we will show that both formulation and programming with dual numbers are remarkably simple for analysis of complicated spatial mechanisms within the programming paradigm of CH. With computational capabilities for dual formulas in mind, formulas for analysis of spatial mechanisms are derived differently from those intended for implementation in computer programming languages without dual data type. We will demonstrate some formulation and programming techniques in the programming paradigm of CH through a displacement analysis of the RCRCR five-link spatial mechanism. A CH program that can obtain both numerical and graphical results for complete displacement analysis of the RCRCR mechanism will be presented.
Automatic Bar Stock Selection for Machining
Authors: Leonard John E. , Shah Jami J.
Published: March 2021

Given a feature-based CAD model of a part’s geometry, the problem is to select the shape and size of bar stock from which the part can be made. It is assumed that standard stock shapes and sizes available in the workshop varies, so the task is to select the best suited stock geometry and cut-off length from the available inventory. Automatic workpiece selection involves the interrogation of a part database to determine the part’s shape characteristics, and to match the shape with available geometries. The requirements of a system to perform this task are presented along with several methods of determining the appropriate shape — GT coding, shrinking box, silhouette projection, point network, principal machining directions, and face extension. None of these methods is sufficiently robust by itself, so a combination of methods is required. Based on this hybrid technique, a system to perform automatic workpiece selection was designed and implemented. A coding scheme is used to select the workpiece shape, based on primary features and their relationships. Once the shape is selected, it is matched with available workpiece shapes. The workpiece is then sized using a version of the bounding box method.
Algorithms to Detect Geometric Interactions in a Feature-Based Design System
Authors: Talwar Rajeev , Manoochehri Souran
Published: March 2021

This paper presents efficient and accurate algorithms for the analytical detection of geometric interactions between features in a CAD environment. The developed methodology is meant to be utilized in a knowledge-based design system using feature-based modeling. The algorithms take surface information from the CAD system and use geometric inferencing to evaluate these interactions. Features represented by both convex and concave polyhedra are considered. The methodology developed here is able to deal with concave features effectively and, therefore, eliminates the need for their decomposition into convex sub-features. Sets of conditional statements based on simple and elegant rules have been developed to distinguish different types of interactions. Feature interactions are classified as intersecting or non-intersecting. For the non-intersecting cases, the features can be contained or separate and, for both cases, they can touch each other through an edge, a vertex and/or a surface. For the intersecting cases, intersections through a surface, an edge, a common edge and a common surface are identified. For all the cases the vertices, edges and surfaces involved in the interactions are identified and the relevant distances are evaluated. A computer program has been successfully implemented for polyhedral features and examples have been given to demonstrate its effectiveness.
Behavior of Structures Using Simple Plastic Hinge Theory
Authors: Maruthayappan Ramakrishnan , Lankarani Hamid M.
Published: March 2021

The behavior of structures under the impact or crash situations demands an efficient modeling of the system for its behavior to be predicted close to practical situations. The various formulations that are possible to model such systems are spring mass models, finite element models and plastic hinge models. Of these three techniques, the plastic hinge theory offers a more accurate model compared to the spring mass formulation and is much simpler than the finite element models. Therefore, it is desired to model the structure using plastic hinges and to use a computational program to predict the behavior of structures. In this paper, the behavior of some simple structures, ranging from an elementary cantilever beam to a torque box are predicted. It is also shown that the plastic hinge theory is a reliable method by comparing the results obtained from a plastic hinge model of an aviation seat structure with that obtained from a finite element model.
Feature-Based Design for Mill-Turn and 3-Axis Machining
Authors: Henderson D. L. , Anderson D. C.
Published: March 2021

A feature-based design environment for machined parts exploiting the capabilities of mill-turn machining centers is described. Part models for prismatic, turned and mill-turn parts, as well as hybrid parts such as turned parts with prismatic features, are created with parametrically defined features. Two-dimensional (2-D) profile features are used for creating surfaces of revolution for turned parts. Mill-turn features can be added to cylindrical base features, and traditional prismatic features, such as slots and holes, can be used with prismatic or cylindrical parts. Features are hierarchically positioned and oriented in a unified scheme that includes position and form tolerances. The vector-based tolerance representation facilitates interactive three-dimensional (3-D) design and provides information needed by downstream applications, such as automatic process planning and inspection.
Geometric Influence of a Molded Part on the Draw Direction Ranges and Parting Line Locations
Authors: Weinstein Marc , Manoochehri Souran
Published: March 2021

This paper presents a methodology based on the geometry of the injection molded part to identify the draw direction range and parting line locations. These parameters are shown to be a function of the interaction of the outward normals of the surfaces which have been divided into concave and convex regions of the part. This approach can also be applied incrementally to determine these mold parameters for a part as design features are added. The designer can then select from the choices provided to find the optimum parting line location and draw direction using heuristic rules. An absence of an allowable draw direction indicates the presence of an undercut which complicates the mold by requiring a side action so that the mold cost increases. The designer can either redesign the part or accept the undercut by specifying a side core or cavity. Design examples are provided which illustrate the effectiveness of the developed approach.
A Knowledge-Based Approach to Design Partial Journal Bearings
Authors: Badar M. Affan , Guntur Rao R.
Published: March 2021

Various methods for designing hydrodynamic partial journal bearings are reviewed and an integrated and dependable design procedure is (developed. Knowledge and rule bases pertaining to the design of journal bearings having arcs of 180°, 120°. and 60° are either gathered or derived and represented properly. An expert system is developed using the databases and rulebases. The bearing design is based on one of the following decision criteria: the maximum load, the minimum friction, or the optimal clearance The expert system makes an exhaustive search for all the design solutions. Utility value of each of the final solutions is calculated and the design solutions having utility values above a certain limit are stored The results are presented to demonstrate the usefulness of the knowledge-based approach.
Configuration Design of Structures Using Discrete Optimization Approach
Authors: Shim Patrick Y. , Manoochehri Souran
Published: March 2021

This paper presents a methodology for the generation of fully stressed shape configuration design of structures. An important aspect of this approach is the ability to modify the topology as well as the boundary shape of the object represented by a finite element model Therefore, features such as holes or slots can be added even though they have not been part of the initial model. This work is based on altering the finite element structure by removing or restoring elements to generate fully stressed designs subject to constraints on maximum stress value and maintenance of connectivity between the elements. The algorithm uses binary value integer programming for the discrete optimization process with the normalized elastic modulus of each design element selected as design variable. The optimization results consist of a zero or one integer solution which indicates the states or the elements in the model The integer zero indicates that the modulus of the design element is zero and therefore the element is a candidate for deletion from the model The integer one represents no change in modulus value compared to the original model and thus these design elements stay in the model. The developed approach can modify the inner and the outer shape of the structure without the need for a remeshing after each iteration and this reduces the computational time significantly. Design examples are provided to demonstrate the effectiveness of the proposed optimal design methodology and to illustrate the steps involved in this process.
Multiple Objective Design Optimization by Estimating Local Utility Functions
Authors: Yang Jian-Bo , Sen Pratyush
Published: March 2021

This paper presents the application of an interactive multiple objective decision making (MODM) procedure to design synthesis. This procedure is composed of an interactive step trade-off method (ISTM) and the estimation of local utility functions. The ISTM method is used as a preference learning process to assist a designer (decision maker or DM) in generating a representative sub-set of efficient designs (solutions). In this learning process, the DM is expected to compare the generated solutions in a pairwise manner to express his preferences. A set of additive local utility functions are then estimated to help the DM search for his best compromise solution. A multiple objective design synthesis problem is examined using the procedure.
A Survey of Electronic Package Manufacturing Analysis Methods Suitable for Integration With Multidisciplinary Optimization
Authors: Korngold Jacob , Gabriele Gary A.
Published: March 2021

The objective this paper is to improve concurrent engineering of electronic packaging design problems by addressing issues of integrating manufacturing as a discipline in multidisciplinary design analysis and optimization (MDA/O) problems. To met this goal, MDA/O and electronic package manufacturing analysis modules are examined. Manufacturing can participate as a discipline in MDA/O problems if analysis capability exists to relate design variables to quantitative manufacturing performance metrics. Analysis modules for sheet metal enclosure and printed circuit board fabrication were found to meet these requirements. In formulating MDA/O problems with manufacturing as a discipline, questions arise about the role of manufacturing analysis, design variables selection, performance metrics, and constraint definitions. Answering these questions is the subject of continuing research.
On Global Design Description for Orientational Strength Optimization
Authors: Pedersen Pauli , Hammer Velaja B.
Published: March 2021

The idea of global design description used frequently in shape optimization, is extended from curve to surface parametrization. The design is given as a linear combination of orthogonal functions. Application to orientational design of laminates for strength optimization is used as an example, but the technique is directly applicable to design also of thickness distribution. The advantages by this design description are many, including control on smoothness, control on slopes, and control on connections at the boundaries. This simplified parametrization of the design makes it possible to work with only a few design variables, say 25 for a whole design domain.
Intrinsic Geometry for Shape Optimal Design With Analysis Model Compatibility
Authors: Widmann James M. , Sheppard Sheri D.
Published: March 2021

This paper presents a comparison of geometric modeling techniques and their applicability to structural shape optimization. A method of shape definition based on intrinsic geometric quantities is then outlined. Explicit knowledge of curvature and arc length allow for a quantitative assessment of the compatibility of analysis model with the design model when using finite elements to determine structural response quantities. The compatibility condition is formalized by controlling finite element idealization error and is incorporated into the shape optimization model as simple bounds on the curvature design variables. Several examples of shape optimization problems are solved using sequential quadratic programming which proves to be an effective tool for maintaining the geometric equality constraints that arise from intrinsically defined curves.
An Approach to the Problem of Vibration: Structural Modification by Optimizing Density Distribution
Authors: Kawabe Yoshiko , Yoshida Shinobu
Published: March 2021

This paper proposes a basic method for designing light and rigid structures that maximize the natural frequency of the structure for a designated mode. A design variable ‘density’ is introduced into the finite element method and is related to the material properties of a 3-dimensional solid element. Thus, a structure is expressed as a density distribution inside its occupiable domain, and the optimal structure is obtained by searching for the most suitable density distribution. The dynamic characteristics of the structure are improved by repeatedly modifying its density distribution.
Application of Genetic Algorithm for the Support Location Optimization of Beams
Authors: Wang Bo Ping , Chen Jahau Lewis
Published: March 2021

Genetic algorithms are adaptive procedures that find solutions to problems by an evolutionary process that mimics natural selection. In this paper, the use of genetic algorithms for the selection of optimal support locations of beams is presented. Both elastic and rigid supports are considered. The approach of adapting the genetic algorithms into the optimal design process is described This approach is used to optimize locations of three supports for beam with three types of boundary conditions.
A New Design of a Bicycle Frame: An Example for an Effective Layout Procedure Based on FE-Simulation of Biological Growth
Authors: Baumgartner A. , Mattheck C.
Published: March 2021

On the basis of the axiom of constant stress two optimization procedures have been developed for the improvement of technical load carriers. Specially the goals of lightweight design and high fatigue resistance are considered.

The SKO method generates lightweight structures for a defined loadcase by simulating the adaptive mineralization of bones. A subsequent shape optimization with the CAO method results in a design with a homogeneous stress distribution on the surface. This prevention of localized high stresses leads to a considerable increase in fatigue life. With the example of a new bicycle frame the efficiency of a combination of both to a complete layout procedure is demonstrated.
Activity-Based Costing in Design for Product Retirement
Authors: Emblemsvåg Jan , Bras Bert
Published: March 2021

In this paper, an approach is presented to estimate the cost incurred by different designs based on Activity-Based Costing (ABC). The suitability of utilizing ABC in design is explored in the context of design for product retirement. A comparison is made with a number of approaches for estimating product life-cycle cost. In comparison to other costing schemes, ABC has the advantages that it can trace both direct and indirect (overhead) costs correctly back to where these costs actually were incurred. This ‘traceability’ facilitates the identification of the most cost inefficient parts of the design, which makes ABC much more suitable for design decision making than other costing schemes. In general, ABC is also more accurate. Although the costs related to any part of a product’s life-cycle can be estimated, an automobile product retirement example is used to illustrate the usage of the approach described. In the example, a decision has to be made whether to pursue a recyclable car or a non-recyclable car. Future work is identified, primarily related to the inclusion of uncertainty in the approach presented.
New Adaptive Tools Dedicated to Surfacic Meshes Integrated Into a C.A.D. Environment
Authors: Noël Frédéric , Léon Jean-Claude , Trompette Philippe
Published: March 2021

The integration of CAD information and Finite Element Analysis is one of the important problems addressed by the design automation requirements. In case of parts involving free-form surfaces, the creation and adaptation of a mesh are still one of the bottlenecks attached to the search for competitive design.

A solution is proposed which inserts a mesh adaptation software into the CAD-FEA chain. Full geometric data of free-form surfaces is used as input together with an initial approximate mesh. Geometric and mesh information on their own, as well as together, use extensively the concept of classification introduced here. Furthermore, topologically and geometrically layered adaptation tools are provided which achieve radaptivity, mesh coarsing, mesh refinement and edge swapping treatments.

The toolkit thus available is demonstrated on examples and its integration requirements are all developed along its description.
Planning Near Time-Optimal Trajectories for Robot Manipulators Along Given Paths
Authors: González-Baños Héctor H. , Gordillo José-Luis
Published: March 2021

This paper extends a previous method aimed to compute discrete time-optimal trajectories of “dot-like” robots to consider the general case of robotic manipulators. The resulting trajectories provide the torque command at each actuator for following a given path in minimum time while respecting the constraints imposed by the manipulator model.

The proposed method makes use of a modified manipulator dynamic model in terms of γ, the arc length parameter which defines the trajectory in the joint space q. The search for a solution is done in the space specified by γ and its derivative ν (the pseudo-speed scalar). In this space we define the features of the solution in order to design an efficient algorithm to compute the time-optimal trajectory. We determine bounds to the model components, such that the optimal solution lies below a curve limiting the area Ω, area in which all possible solutions fit.

The algorithm performs, inside Ω, an ascendent search of the limiting curve; this strategy permits the curve obtained at each intermediate step to be a valid solution.
A Scheme of a Knowledge Based System for Optimal Modelling and Design of Robots
Authors: Lawo Michael
Published: March 2021

Based on a finite element model the deformations and vibrations of a robot structure are calculated for different configurations (layouts). The results of the analysis are verified by measuring the corresponding deformations and velocities. The time history of velocities at different points of the structure in test positions is recorded. Out of the time history by modal analysis the natural frequencies are determined. The structural model is checked by the comparison of corresponding analysed and measured values A nonlinear optimization method with the structural parameters as variables of the model is used for the solution of this identification problem. The result is a verified and sufficient structural model of the real structure. Out of the experiences a knowledge based system for the modelling and simulation of robot structures is conceived. The concept of the system is presented.
Feasibility Study of Crash Optimization
Authors: Yang R. J. , Tseng L. , Nagy L. , Cheng J.
Published: March 2021

A feasibility study of using numerical optimization methods for crash analysis is presented. Software required for numerical optimization includes parametric modeling (Pro/ENGINEER), automatic mesh generation (PDA/PATRAN3), nonlinear finite element analysis (RADIOSS), and optimization methods (CONMIN & DOP). Both single- and multiple-objective formulations are used for numerical optimization and result in better designs. It was found that crash optimization is feasible but costly and that finite element mesh quality is essential for successful crash analysis and optimization. A simplified front horn was used to demonstrate this approach.
Novel Methods in the Displacement Analysis of Spatial Mechanisms
Authors: Fischer Ian S.
Published: March 2021

An aspect of dual-number coordinate-transformation matrices is used to establish iterative methods for determining the rotational and translational displacements in the kinematic analysis of complex spatial mechanisms.
Bézier Curves on Riemannian Manifolds and Lie Groups With Kinematics Applications
Authors: Park Frank C. , Ravani Bahram
Published: March 2021

In this article we generalize the concept of Bézier curves to curved spaces, and illustrate this generalization with an application in kinematics. We show how De Casteljau’s algorithm for constructing Bézier curves can be extended in a natural way to Riemannian manifolds. We then consider a special class of Riemannian manifold, the Lie groups. Because of their algebraic group structure Lie groups admit an elegant, efficient recursive algorithm for constructing Bézier curves. Spatial displacements of a rigid body also form a Lie group, and can therefore be interpolated (in the Bezier sense) using this recursive algorithm. We apply this algorithm to the kinematic problem of trajectory generation or motion interpolation for a moving rigid body.
Five Position Synthesis of Spatial CC Dyads
Authors: Murray Andrew P. , McCarthy J. Michael
Published: March 2021

This paper presents a new technique for determining the fixed axes of spatial CC dyads for rigid body guidance through five finitely separated positions. A CC dyad is a kinematic chain consisting of a floating link connected by a cylindric joint to a crank which in turn is connected to ground by a second cylindric joint. The lines that can be axes of the fixed joint are shown to be obtained from a “compatibility platform” constructed from selected relative screw axes associated with the five specified displacements. We show that the screw axis of the displacement of this platform is a fixed axis of a CC dyad compatible with the five positions. Roth’s original example is presented to verify the calculations. The specialization of this procedure to planar and spherical five position synthesis is also presented.
Application of Fuzzy Set Theory to Planar and Spatial Mechanism Design
Authors: Krishna Kota Murali , Krishnamurthi Subramanyam , Kramer Steven N.
Published: March 2021

This paper describes how Fuzzy Set Theory and Fuzzy Numbers can be applied to the synthesis of planar and spatial mechanisms. The main advantage of using Fuzzy Set Theory over other methods of mechanism synthesis is that uncertainties in positions, rotations and link lengths can be quantified using the concept of membership functions. A membership function is an explicit representation of the deviation of the value of a parameter from its specified value. Numerical examples include the synthesis of a four-bar path generating mechanism with uncertain prescribed timing as well as uncertain path points and the RSSR spatial function generating mechanism. This work is expected to be a significant contribution to optimal mechanism design.
On the Optimum Design of Planar and Spherical Drag-Link Mechanisms
Authors: Zanganeh Kourosh E. , Angeles Jorge
Published: March 2021

In this paper, two different procedures are proposed for the optimum design of drag-link planar and spherical four-bar linkages. First, we present a new graphical synthesis method based on 3-dimensional parametric plots of three commonly-used performance indices, namely, the design error, the structural error, and the transmission quality. The plots reveal that minimum values of the design and structural errors occur at a common point in a subspace that is defined by mobility constraints. Second, we propose a numerical procedure based on a constrained nonlinear least-square scheme that aims at optimizing the design error and transmission quality of the linkage. As shown by numerical examples, the graphical method provides a general picture of the problem under study and can be used to evaluate the goodness of the synthesized linkages.
Branch, Mobility Criteria, and Classification of RSSR and Other Bimodal Linkages
Authors: Ting Kwun-Lon , Dou Xiaohong
Published: March 2021

The article presents a classification scheme based on the number of branches that a linkage may have and a general Grashof type mobility criterion for a group of over sixty types of four-, five-, six-, and seven-bar linkages, including RSSR, RSSP, RPSC, RSCP, RCSP, RCCC, and Duffy’s Groups 1 and 1* spatial linkages (1980). The criterion is derived from the quartic discriminant of the quadratic equation relating the input and output displacements. It has the simplicity compatible to that of the Grashof criterion and includes the Grashof criterion but without its ambiguity on the branch problem. The derivation and the demonstration are carried out through RSSR and RSSP mechanisms. The simplicity and generality of the proposed criterion surpass any mobility criterion available so far for any spatial linkage.
Detection of Improper General Spatial Kinematic Chains With Different Types of Pairs
Authors: Kong Xian-Wen , Yang Ting-Li
Published: March 2021

Improper general spatial kinematic chains (GSKCs) due to the effect of pair types may be generated during the process of topological synthesis of GSKCs with different types of pairs. Thus, detection of improper GSKCs is necessary in topological synthesis of GSKCs with different types of pairs. Unfortunately, it is still an unsolved problem. In this paper, a method for detecting improper GSKCs is presented. Both a necessary and sufficient condition and a sufficient condition for proper GSKCs with R, P, H, T and C pairs are introduced at first. Based on these two conditions, an algorithm to detect improper GSKCs is then developed which is very efficient and suitable for topological synthesis of GSKCs with R, P, H, T and C pairs. The proposed algorithm has been applied to topological synthesis of 1- and 2-loop, single degree of freedom GSKCs with R, P, H, T and C pairs and the corresponding atlas is obtained.
A Study of the Position Problem for Multi-Circuit Mechanisms
Authors: Waldron Kenneth J. , Sreenivasan S. V.
Published: March 2021

It has been known for a very long time that the commonly used techniques for solution of the position problem of planar mechanisms are not general. Nevertheless, it is remarkable that many textbooks, and even reference books on planar kinematics do not acknowledge this fact. Others mentioned it briefly in passing. Even classic reference works such as Hain (1967) simply state that those problems which cannot be solved by conventional methods should be solved by trial and error.