bluuebunny/crossref_metadata_2025 huggingface dataset:
Super-Finishing Tool Path Generation for Digitized Models Supported by Super-Finishing Form Feature Recognition
Authors: Saglio Emilio , Mandorli Ferruccio , Cugini Umberto
Published: March 2021

The realization of sculptured shapes using CAD systems is still today a very complex and time consuming operation. For these reasons, design by physical modeling is still in use and remains in force in many industries (automotive, ski boots, sport articles).

For the manufacturing of complex free-form surfaces, in situations in which it is more desirable to proceed from a physical model to a numerical definition rather than use mathematics to derive the physical part, copy milling techniques are widely used.

This paper gives a brief overview about copy milling techniques for 3 axis copy milling machines, and proposes a feature based method to support an automatic tool path generation for the super-finishing phase. The proposed method is divided in two parts: super-finishing features recognition and tool path generation.

Using copy milling techniques, the model of the object to be milled is obtained by digitizing. Therefore a global mathematical surface description of the model does not exist.

In such a situation a model interpretation phase is required to recognize the super-finishing features and thus proceed to the tool path generation.

A two step algorithm for super-finishing feature recognition on a digitized model is proposed: features arc recognized on the basis of the digitized point density and the normal vectors of the triangles generated by the surface reconstruction (based on Delaunay triangulation method).

The tool path is then generated using a method based on the calculation of the Voronoi diagram on the area identified as super-finishing feature.

The super-finishing feature recognition and tool path generation modules have been integrated as part of a more general CAM system for copy milling called HICAM. The architecture of such a system will be presented together with examples of solutions obtained by means of the use of the implemented prototype modules.
Fuzzy Part Coding for Group Technology
Authors: Ben-Arieh D. , Lee S. E. , Chang Ping Teng
Published: March 2021

Contemporary Group Technology (GT) methods apply coding schemes as a popular method for capturing the design and manufacturing information pertinent to the parts to be grouped. Coding schemes are very popular and many different coding systems are commercially available. The main disadvantage of current coding systems, however, is their generality and lack of informative representation of the parts.

This paper presents a new methodology for coding parts using fuzzy codes. The methodology is general and applies to attributes that have a crisp value (e.g. “length”, “ratio of length to diameter”), an interval value (e.g. “tolerance”, “surface roughness”) or a fuzzy value (e g. “primary shape”).

The methodology considers the range of attributes relevant for the grouping, and therefore is tuned and adjusted to the specific collection of parts of interest This method creates a more informative coding scheme which leads to improved variant process planning methods, scheduling and inventory control as well as other manufacturing functions that utilize GT.
A Database Tool for Managing Customer and Design Information During Product Definition
Authors: Khadilkar Dileep V. , Gershenson John A. , Stauffer Larry A.
Published: March 2021

We developed a new database tool to manage information during the product definition process. This tool is a result of an ongoing research program to coordinate marketing and design engineering efforts in new product developments, and consider the related life cycle issues early in the design process. The database tool facilitates a methodology that integrates customer and design information, and allows reuse of this information during redesign problems. This paper presents the development, implementation, and an example use of the database tool.
A Design Expert System for Full Journal Bearings
Authors: Badar M. Affan , Guntur Rao R.
Published: March 2021

Various architectures used in design expert systems are reviewed. An architecture consisting of several stages of grouped rules is employed and its features are discussed. The architecture uses a rule based production system. Different methodologies for designing hydrodynamic journal bearings are reviewed and an integrated and dependable design methodology is developed In this Turbo Prolog program, initially, the user is asked to enter the required prescriptive and functional specifications and the decision-criterion. Knowledge bases pertaining to this design problem are represented appropriately. The design solutions of successive states are examined for any violations of the design constraints. The expert system ‘Fbear’ makes an exhaustive search for all the solutions. Utility value of each of the final solutions is calculated and the design solutions having utility values above a certain limit are printed in an output file. The results of ‘Fbear’ are compared with those of the previous workers to illustrate its usefulness.
Design of Products for an Agile Manufacturing Environment
Authors: Kusiak Andrew , Feng Chang-Xue
Published: March 2021

Many manufacturing companies have been striving to reduce setup times in order to produce smaller lot sizes and to obtain quicker responses to frequently changing market demands. This paper focuses on the reduction of setup time by design improvements of products. Based on the basic principles of setups and concepts from concurrent engineering, rules for design of products at the feature level are presented. Examples and computational results illustrate that the inter-lot setups and in-lot setups can be reduced by the feature-based design rules. The proposed approach for setup reduction appears to be more cost effective than optimizing the processes and operations where the product designs have been fixed. This research intends to bridge the gap between engineering design and manufacturing.
A Hybrid Approach to Computer-Aided Process Planning for Prismatic Parts
Authors: Zhang Y. F. , Nee A. Y. C. , Fuh J. Y. H.
Published: March 2021

One of the most difficult tasks in automated process planning is the determination of operation sequencing. This paper describes a hybrid approach for identifying the optimal operation sequence of machining prismatic parts on a three-axis milling machining centre. In the proposed methodology, the operation sequencing is carried out in two levels of planning: set-up planning and operation planning. Various constraints on the precedence relationships between features are identified and rules and heuristics are created. Based on the precedence relationships between features, an optimization method is developed to find the optimal plan(s) with minimum number of set-ups in which the conflict between the feature precedence relationships and set-up sequence is avoided. For each set-up, an optimal feature machining sequence with minimum number of tool changes is also determined using a developed algorithm. The proposed system is still under development and the hybrid approach is partially implemented. An example is provided to demonstrate this approach.
The Best Least-Squares Line Fit
Authors: Alciatore David G. , Miranda Henry P.
Published: March 2021

This paper presents a method for determining the least-squares best-fit line through a set of two-dimensional data. The algorithm is orientation independent and does not rely on knowledge of ordinate and abscissa accuracy. To simplify the analysis, the best-fit line is described by two parameters: q, the angle from the horizontal axis, and r, the perpendicular distance from the origin. This parameterization results in general robust solution resulting in no degenerate cases or indeterminacies. The final results are presented in the standard form, Ax + By = C.
CAD Based Inspection Analysis and Error Display
Authors: Cardew-Hall Michael J. , Dench Phillip
Published: March 2021

Modem inspection devices generate large quantites for error data for analysis. This paper describes a CAD based inspection analysis system that utilizes this data. Such a system is requires 1) the definition of error types, 2) the incorporation of tolerances into CAD definitions, 3) generation of errors between actual and nominal CAD geometry, 4) datuming of the geometries, 5) analysis of the errors and 6) display of those errors. The first 4 points are reviewed and a system for analysing and displaying the errors described. Such a system for aerofoil type geometry has been implemented within the CADDS4X CAD system and is described.
An Off-Line Graphical Environment for Programming Robots Using Commercial CAD Systems
Authors: Abdel-Malek Karim A.
Published: March 2021

Because current robot teaching methods are inadequate to fully control a high accuracy manipulator, the concept of a graphical interface which combines both teaching and programming methods is presented here.

The complexity of user interfaces has become significant as manipulators and other programmable automation are applied to more industrial applications. Three dimensional visualization is an increasingly important aspect of the problem facing robotics programmer. Often the effector coordinates passed to the manipulator are not easily visualized in space. The introduction of a graphical environment the reduces the task of visualizing points, orientations, and trajectories. The environment developed here (the “TR-Environment”) provides the user with an off-line programming method where logic, repetitive tasks, and sensory control can be simplified. The environment consists of the integration of commercial CAD packages with computer languages. The program utilizes the so called “NODES” which define the six generalized coordinates and the state of the end-effector at a point in space. Trajectories in space can be planned by connecting nodes via “entities”. A new language (“Criptic”) associated with nodes where program branching, sensory control, digital communication, and adaptive control occurs, has been developed.
Nonlinear Shell Deflections With Thickness Updating
Authors: To C. W. S. , Liu M. L.
Published: March 2021

In the present investigation the incremental Hellinger-Reissner variational principle, a hybrid-strain based formulation and an updated Lagrangian formulation are adopted to derive explicit expressions for element stiffness matrices of various flat triangular shell finite elements. These elements are developed for application to the analysis of thin and thick shell structures undergoing large geometrically nonlinear deformation at finite strain. Correct representations of finite rotations and the specifically chosen strain field maintain appropriate rigid body motions and prevent shear locking phenomena. Consideration of thickness updating and a finite strain formulation relaxes any plane stress assumptions and enables the analyst to deal with three-dimensional constitutive models. Two numerical examples are presented to demonstrate the performance of the elements.
Use of Finite-Element Stress Analysis in the Design of a Tank-Cannon-Launched Training Projectile
Authors: Hollis Michael S. L.
Published: March 2021

The U.S. Army Armament Research. Development, and Engineering Center (ARDEC) recently expressed a need for a tank-cannon-launched training projectile with reduced penetration capability. The expressed primary design goals for this projectile were to minimize the probability of personnel injury and materiel loss in the event of an accidental impact during a training exercise. In order to meet these design goals, the solid-steel flight body of a current kinetic energy (KE) training projectile, the M865IP, was replaced with a hollow aluminum configuration. Because of the incorporation of aluminum, the structural integrity of the entire projectile during launch was put in question. Thus, a thorough stress analysis of the new design was conducted to alleviate concerns about its structural integrity.

Two-dimensional, axisymmetric, quasi-static stress analyses were performed on two new KE training projectile designs. The first analysis indicated that structural failure was possible in the aft portion of the projectile due to compressive loading by the gun gases. Structural failure in this case would be circumferential yielding of the hollow flight body. The aft portion of the round was redesigned, and subsequent stress analysis showed the possibility of structural failure to be resolved. The finite-element modeling approach, the applied boundary conditions, and the results of the stress analyses conducted, based on use of the von Mises failure criterion, will be discussed in detail.
Finite Element Analysis for a CAD of a Concrete Mixer Drum
Authors: Badawi Hossam S. , Mourad Sherif A. , Metwalli Sayed M.
Published: March 2021

For a Computer Aided Design of a concrete truck mixer, a six cubic meter concrete mixer drum is analyzed using the finite element method. The complex mixer drum structure is subjected to pressure loading resulting from the plain concrete inside the drum, in addition to its own weight. The effect of deceleration of the vehicle and the rotational motion of the drum on the reactions and stresses are also considered. Equivalent static loads are used to represent the dynamic loading effects. Three-dimensional shell elements are used to model the drum, and frame elements are used to represent a ring stiffener around the shell. Membrane forces and bending stresses are obtained for different loading conditions. Results are also compared with approximate analysis. The CAD procedure directly used the available drafting and the results were used effectively in the design of the concrete mixer drum.
Zero Turn Radius Vehicle Incorporating Computer-Controlled “Intelligent Castors”
Authors: Spark I. J. , Besselink B. C.
Published: March 2021

This paper describes how a computer controlled steering system can be used to increase the ability of zero turn radius vehicles to traverse steep slopes. This objective is achieved by replacing free wheeling front castors with “castors” which are positively rotated about a vertical axis to steering angles which are appropriate to the speed difference between the independently driven rear wheels and held at these angles.

This relatively simple “Steer by wire” system foreshadows the development of much more sophisticated steering systems than can be achieved by traditional mechanical linkages.
The Use of Spreadsheets in Compressible Flow Courses
Authors: Young Edward F.
Published: March 2021

The spreadsheet has gained wide acceptance in the engineering community, but may not be as widely used in the teaching of various engineering courses as it could be. This paper addresses a specific set of courses, those in compressible flow, and presents several different uses for a spreadsheet in such courses. In all applications, the student must manipulate the relevant equations that describe the physics of the flow. By using a spreadsheet, all results can be easily plotted, thus providing the student with additional insight. The examples presented lead to using the spreadsheets exclusively, rather than tables and graphs, for obtaining compressible flow parameters. Sample spreadsheets and plots are presented. Following such a concept leads to speedier and more accurate results and permits the student to devote more time to analysis rather than the mechanics of looking up data.
Using Exponential Cubic Splines to Predict Low Temperature Behavior of Elastomeric Materials
Authors: Shoup Terry E. , Fegan George R.
Published: March 2021

Because of their desirable elastic and energy absorbing properties, elastomeric materials have been widely used as shock mounts and pressure seals. The high sensitivity of the elastic modulus of these materials to changes in temperature has been a source of considerable difficulty to the development of robust design methods based on analytical techniques. This paper presents a simple analytical method for predicting the elastic modulus for a group of five different types of elastomers when used at low temperatures. The method is based on the application of exponential cubic spline curves to smooth experimental data. The method is applied to experimental data from the literature to illustrate its usefulness.
Robust Product Design Using Manufacturing Adjustments
Authors: Otto Kevin
Published: March 2021

Tuning variables represent factory floor manufacturing adjustments commonly used to correct variational noise errors in a product. Some examples are voltage supply adjustments, adjustable links and screws, or shims. This paper presents methods to determine the increased performance and robustness when using different possible manufacturing adjustments. All possible potential tuning adjustments that exist in a design are identified. Given this, the tuning variable model can be used to calculate the reduced product variation when using any of the potential tuning adjustments, including none at all. This process can be used to help select which product variables should be adjusted, based on the increased robustness to noise and the increased difficulty in manufacture. Doing so allows for more robust product performance at reduced manufacturing expense, by allowing the potential adjustment on many different possible variables. This is better than always adjusting the source of the manufacturing errors, which can be expensive.
Organizing and Managing Customer Requirements During the Product Definition Phase of Design
Authors: Gershenson John A. , Khadilkar Dileep V. , Stauffer Larry A.
Published: March 2021

We developed a methodology for organizing design requirements at the beginning of the design process which helps Marketing, Engineering Design, and all other stakeholders communicate from the outset. The methodology uses an expanded definition of a product’s customer which includes not only the end user, but anyone associated with the product at any point from concept through retirement. The methodology has a taxonomic structure to delineate customer requirements in four main areas: end user requirements, corporate requirements, regulatory requirements, and technical requirements. This methodology has the same objective as Quality Function Deployment yet is more robust.
Integrating the Results of a Laboratory Study Into the Development of a System for the Support of Simultaneous Engineering
Authors: Lam Azriel , Rückert Carsten , Tegel Oliver
Published: March 2021

At our institute, a system for the support of Simultaneous Engineering is being developed. The results of a laboratory study on strain and stress of CAD design work have an influence on this development. Integrating the requirements for CAD-systems that could be figured out in this study, the software will be of more use for practice, and will satisfy the customer’s expectations.
Geometric Modeling and Simulation of Mechanical Assemblies With Elastic Components
Authors: Fang Yong , Liou F. W.
Published: March 2021

In this paper, the implementation of a modeling system for the simulation of three dimensional mechanical assemblies with elastic components is presented. A mechanical assembly is modeled as a multi-body system with changing topologies. The elastic behavior can be automatically modeled using finite element method. With this simulation tool, a designer can interactively create an assembly of mechanical components ready for dynamic and elastic analysis. This paper presents a prototype of the modeling system.
A Computer Aided Visual Reasoning Tool for Missing View Problems
Authors: Zhao Hong , Kim Yong Se
Published: March 2021

The ability of an engineer to visualize and reason about geometric aspects of physical objects and processes is crucial in the success of engineering activities. The paper presents the development of a prototype visual reasoning system which aims at increasing engineering students’ visual reasoning capabilities. Specifically we take the missing view problem which requires students to construct any valid solid and a corresponding missing orthographic view when they are given two orthographic views. Sweeping operations, which are the reverse procedure of orthographic projection, are used to solve missing view problems by forming the boundary faces of a solid from the loops of orthographic views. This geometric operation forms a primary user interface of the system in visually reasoning about the construction of 3-D solid given the constraints by two orthographic views.
Automatic Development Generation for Thin-Walled Objects
Authors: Lin Yu-Long , Yang D. C. H.
Published: March 2021

This paper presents an analytical study on automatic development generation of thin-walled objects. Formulas based on mechanism theory are derived to determine the required number of seam lines for developing thin-walled objects. Subsequently, the seam line locations are determined via the identification of the minimum required seam line number at each vertex. An algorithm based on spanning tree technique has been developed to automatically generate all possible developments. Configurations with geometrical violations can be automatically detected and deleted. In addition, a new unfolding technique based on individual surface transformation has been presented. This technique requires less computational time in the unfolding process than the traditional sequential transformation method.
Computer-Aided Design Synthesis Using Syntactic Solid Modeling
Authors: Theodoracatos Vassilios E. , Guan Xiaogang
Published: March 2021

This paper presents a new Computer-Aided Design (CAD) synthesis model which uses Plex Grammar as structural relationship descriptors and NURBS surface representation for constructing standard and non-standard solid entities. Here, the designer uses a syntactic design methodology for early topological and geometrical definition of the structure of concept alternatives resulting from the design process. This syntactic scheme provides the capability of describing a large set of complex structures by using a small set of simple entities. The recursive nature of the grammar and the hierarchical representation of the structure makes the description of complex structures simple and under the direct control of the designer. An object structure constructive tree is generated and subsequently translated into Plex Grammar production rules in order to form an Interconnection Matrix (ICM) expressing. The resulting Plex structure defined in the ICM expresses the topological information among entities which form the specific types of objects. By modifying the Plex grammar rules, various objects with different geometry and topology can easily be reconstructed. Compared to conventional solid modeling techniques, this approach provides more systematic object generation, easy manipulation and modification, control over congruity and the ability to represent sculptured shapes. Several examples of syntactic solid modeling applied in design synthesis will be presented for further usage in downstream applications.
Design for Injection Molding: Using Dimensional Analysis to Assess Fillability
Authors: Mehl Douglas C. , Beiter Kurt A. , Ishii Kos
Published: March 2021

This paper addresses the determination of wall thicknesses and gating schemes in the preliminary design of injection-molded plastic parts. Today, most of the existing design guidelines come in the form of experience-based qualitative rules. If the designers already have a detailed geometry of the part, the numerical process simulation program provides another form of design aid. There exists a huge gap between these two types of design aids; the experience-based guidelines are often too vague, while the process simulation programs come too late to impact preliminary part design. To fill this gap, this paper develops physics-based guidelines that utilize dimensional analysis techniques. Experiments and simulation studies can deduce non-dimensional relationships between flow length, thickness, material, and process parameters. The guidelines will aid plastic component designers in determining wall-thickness, gating schemes, and in selecting the material in the preliminary stages of part design. This paper describes the formulation of the non-dimensional charts for fillability assessment, and explains the use of these charts in part design. We further outline an ongoing experimental program to validate and refine our formulation.
Detection and Evaluation of Planes of Partial Symmetry in CAD Models
Authors: Sturges Robert H. , Hunt David O.
Published: March 2021

Components with subtle asymmetry require more handling time in manual and automatic assembly. Models of assembly processes predict that almost half of the acquisition effort derives from the recognition of feature subtlety and the symmetries of the part. An algorithm is presented which detects and evaluates the axes of symmetry and partial symmetry for a wide variety of asymmetries, features, and aspect ratios. The orientations of the partial symmetry axes are then used to calculate the effect on assembly time. The ability to locate axes in an object that are not orthogonal is demonstrated. Currently the algorithm can only examine 2-D shapes, and an approach to fully automated evaluation of a 3-D object is presented.
Computerized Simulation of Transmission Errors and Shift of Bearing Contact for Hypoid Gear Drive With Conjugate Gear Tooth Surfaces
Authors: Litvin Faydor L. , Chen Jui-Sheng , Sep Thomas M. , Wang Jyh-Chiang
Published: March 2021

Computerized investigation of the influence of alignment errors on the transmission errors and the shift of the bearing contact is proposed. The investigation is performed for an imaginary hypoid gear drive with conjugate tooth surfaces. It is proven that the transmission functions caused by misalignment are periodic discontinues almost linear functions with the frequency of cycle of meshing. The above functions can be totally absorbed by a predesigned parabolic function. The shift of the bearing contact caused by misalignment has been determined as well. The performed investigation is based on computerized simulation of meshing and contact of gear tooth surfaces. The machine-tool settings for the generation of the designed gear drive have been determined. Numerical example that illustrates the developed theory is given. The performed investigation allows to determine the influence of gear misalignment on transmission errors, and design a low-noise hypoid gear drive by a properly predesigned parabolic function of transmission errors.
Geometry Design of Roller Gear Cams With Generalized Meshing Elements
Authors: Yan Hong-Sen , Chen Hsin-Hung
Published: March 2021

This paper derives the generalized expression of surface equation for cylindrical, conical, and hyperbolic meshing elements. Based on the generalized equation of meshing elements, generalized mathematical expressions of surface geometry for roller gear cams with cylindrical, conical, and hyperbolic meshing elements are derived by theory of conjugate surfaces, differential geometry, and coordinate transformation. Design examples are given. The result of this work is of necessary for the computer-aided design and manufacturing roller gear cams for industrial applications.
A Uniform Approach to Handling of Feature-Objects in an Advanced CAD System
Authors: Horváth Imre , Kulcsár Péter , Thernesz Vilmos
Published: March 2021

This paper describes a methodology of generation, representation and manipulation of high level modelling entities, called feature-objects. The aim of the related research and development was to specify and implement feature-objects. The methodology has been implemented in the PRODES system that is intended to be a prototype of an advanced design, analysis and process planning system, integrated on the basis of the feature paradigm. First, the related research activities and theoretical backgrounds are studied, then the concept of feature-objects and the method of their uniform handling are introduced. The paper presents the resultant taxonomy of the application process oriented feature-objects. Their definitions are demonstrated through examples. The feature-object composition, that is the product modelling methodology of the PRODES system, is also presented.
Exact Response Analysis and Dynamic Design of Cam-Follower Systems Using Laplace Transforms
Authors: Bagci Cemil , Kurnool Srihari
Published: March 2021

Article presents Laplace transforms utilizing method to determine the responses of the follower systems to any type of motion machined on cams. The exact response of a follower system at any cycle, at any time, or in any time zone is directly determined without the need for numerical integrations. The method permits the study of response for many cycles to determine beat effect, the critical cam speeds, and possible follower jump conditions. Cam profile is corrected to eliminate static error and oscillate follower about exact position. Disk cams with translating roller followers with one and two degrees of freedom are considered in the article. Numerical illustrations are included, where results by other numerical methods (matrix exponential and phase plane-δ) are compared.
Robust Design by Matching the Design With Manufacturing Variation Patterns
Authors: Yu Jyh-Cheng , Ishii Kosuke
Published: March 2021

This paper deals with robust design problems in which variations on design variables have significant correlation. Manufacturing errors often affect design variables with characteristic patterns, that is, the variations are coupled. Robust optimization seeks designs with optimal and robust performance. Designers should match the design to the Manufacturing Variation Patterns (MVP) in the constrained robust optimization procedure. This study focuses on matching the variation patterns found in typical manufacturing processes. It uses quadrature experimental design to approximate the performance variation within the patterns. We redefine the robust constraint activity for designs using MVP and propose our procedure to search for the robust feasible designs. Theoretical development of manufacturing variation matching leads to our case study of heat treated shaft design with minimum dimensional distortion. The paper also outlines our future application in injection molding gear design and challenge in the identification of nonlinear correlated MVP.
Reduction of Acquisition Time Through New Design for Assembly Heuristics
Authors: Sturges Robert H. , Hunt David O.
Published: March 2021

Rearranging component positions and orientations inside products can reduce the acquisition times associated with handling distance and component orientation. Modeling the acquisition process with an information-based Design for Assembly methodology identifies and quantifies acquisition difficulty for manual and automatic processes. Heuristics based on evaluations of acquisition difficulty guide the relocation and reorientation of components inside the product to reduce assembly time. Since acquisition time averages one third of the total assembly time, significant improvements are shown to be feasible. A new information flow from downstream assembly issues into product design is demonstrated.
A Network Reliability Approach to Optimal Decomposition of Design Problems
Authors: Michelena Nestor F. , Papalambros Panos Y.
Published: March 2021

This article addresses the problem of identifying the optimal decomposition of a design problem. Methods for solving decomposed mathematical programming problems require that an appropriate structure suitable for decomposition be identified. This first step consists of identifying linking (or coordinating) variables or functions that effect independent subproblems coordinated by a master problem. We present a network reliability-based solution of the optimal decomposition problem that avoids heuristics and subjective criteria for the identification of linking variables and evaluation of partitions. The relationships among design variables, i.e., the constraint functions, are modeled as the processing units of a network. The design variables themselves are modeled as the communication links between these units. The optimal decomposition problem is then reduced to one of finding the links that have the most effect on the overall network connectivity. Two measures of network reliability, all-terminal and pair-connected reliability, are used as measures of network (and design problem) connectivity. The optimal decomposition is attained by minimizing the network reliability while maximizing the number of operating links.
Structural Optimization Using a Generalized Convex Approximation
Authors: Chickermane Hemant , Gea Hae Chang
Published: March 2021

To reduce the computational cost of structural optimization problems, a common procedure is to generate a sequence of convex, approximate subproblems and solve them in an iterative fashion. In this paper, a new local function approximation algorithm is proposed to formulate the subproblems. This new algorithm, called Generalized Convex Approximation (GCA), uses the sensitivity information of the current and previous design points to generate a sequence of convex, separable subproblems. This algorithm gives very good local approximations and leads to faster convergence for structural optimization problems. Several numerical results of structural optimization problems are presented.
Topology Optimization: A New Micro-Structure Based Design Domain Method
Authors: Gea Hae Chang
Published: March 2021

Topology optimization is the most complicated problem in structural optimization. One common approach is to utilize the concept of the design domain, such as the homogenization method and the density function approach. In this paper, a new micro-structure based design domain method is proposed. This new method gives simple closed-form expressions for effective Young’s modulus and effective shear modulus in terms of phase properties and volume fractions. Using these simple relations, topology optimization problems can be formulated and solved using mathematical programming algorithms. Results of some design examples obtained from the new method are presented.
Aspects on Process Planning Issues in Axiomatic Design
Authors: Vallhagen Johan
Published: March 2021

This paper addresses some limitations of the axiomatic design theory (AD) when designing complex products and matching manufacturing systems. The conclusion is that, for complex manufacturing systems, this cannot be done in such a straightforward way as described in literature. The original method is best used for manufacturing of parts only, i.e. to find the appropriate process variables (PVs).

In the case of complex manufacturing systems, a one-to-one mapping between physical domain and process domain is not possible since not all design parameters (DP) are components. Therefore, an additional process requirement domain (PR), proposed earlier, has been used. With it, the components are extracted from the DP hierarchy and mapped to different spaces in the manufacturing world. In these spaces, PRs and PVs are selected when designing the manufacturing system. An example is given to show the deficiencies and how to use the suggested modifications.
The Measurement Subspaces of Parallel Manipulators Under Sensor Redundancy
Authors: Baron Luc , Angeles Jorge
Published: March 2021

Using the concept of measurement subspaces of the leg-end-point position of general parallel manipulators, a linear kinematic model is derived. For a class of 6-dof leg-kinematic architectures of general geometry, the sets of sensed joints that lead to a measurement subspace are classified into 16 different types. For each of these types, a geometric interpretation and the equations for the computation of the measurement subspace from the readouts of a set of sensed joints, are provided. The design rules on the sensing of parallel manipulators in order to obtain the linear kinematic model are also derived.
Automobile Hood/Fender Design Optimization for Improved Pedestrian Head Impact Protection
Authors: Lemmon David R. , Huston Ronald L.
Published: March 2021

This paper presents procedures for automobile structure design to reduce head injury of pedestrians struck by the vehicle. The fender and hood seam of a 1988 Ford Taurus are modified to absorb the energy of a head impact. Two shape related design parameters are optimized for minimum Head Injury Criterion using finite element simulations. A design is presented which reduces Head Injury Criterion by over 50 percent. All analyses are conducted using the explicit, nonlinear, dynamic finite element code DYNA3D on a Cray YMP/832 supercomputer.
Type Synthesis of Compliant Mechanisms Employing a Simplified Approach to Segment Type
Authors: Murphy Morgan D. , Midha Ashok , Howell Larry L.
Published: March 2021

The formulation of design procedures for rigid-body mechanisms has benefited from the application of type-synthesis techniques. Therefore, with modifications to allow for inclusions of compliance, type synthesis is seen as a useful tool in the design of compliant mechanisms. Previous efforts have developed methods that result in a large number of possible design solutions to a given problem. This paper deals primarily with the development of a simplified compliant-mechanism type-synthesis methodology that limits the number of design solutions considered. The techniques are derived by modifying existing compliant mechanism type-synthesis techniques to yield a simpler model with greater pragmatic value.
Design of the Spatial 4C Mechanism for Rigid Body Guidance
Authors: Larochelle Pierre , McCarthy J. Michael
Published: March 2021

In this paper we present an algebraic formulation for the constraint manifold of the spatial CC dyad in the image space of spatial displacements. We then present a technique, utilizing the constraint manifold, for performing the dimensional synthesis of mechanisms for rigid body guidance through n positions. Finally, we present numerical results for 10 prescribed positions for the coupler of a spatial 4C mechanism.
Analysis and Synthesis of Linear Transmission Mechanisms: Coupled Mechanisms and Mechanisms Wth Prismatic Joints
Authors: Chang Sun-Lai
Published: March 2021

The characteristics of linear transmission mechanisms are studied. Using the characteristics, the kinematic and synthesis of linear transmission mechanisms are expanded. First, the synthesis of mechanisms with prismatic joints in the equivalent open-loop chain is developed. Then the kinematics and synthesis of mechanisms with coupled joint motion are also derived. Two coupled mechanisms are used as examples to demonstrate the application potential in the industry.
Geometrical Algorithms for the Synthesis of Mechanisms
Authors: Jensen Preben W.
Published: March 2021

Geometrical methods are applied to three problems: Proportioning of Four-Bar Linkages with Optimal Transmission Angles, Use of Degenerate Cases of the Burmester Curves, and 6-Point Symmetrical Straight-Line Mechanisms.
General Order Criteria for the Precision Position Synthesis of Single Degree-of-Freedom Planar Linkages
Authors: Mirth John A.
Published: March 2021

The order in which a single degree-of-freedom planar linkage passes through a series of design positions depends on both the relative orientations of a designated input link and the branch characteristics of that same link. The input link must have a continuous rotation as it passes through all design positions that lie on the same branch. The continuous rotation criteria does not apply to design positions on different branches of the linkage. Complete order conditions are presented for linkages with four design positions that lie on one to four separate branches.
“MKCIRCLES”: An Interactive Computer Graphics Design Tool to Solve the Generalized Three-Precision-Position Synthesis Problem
Authors: Cheng Pi-Ming , Rizq Raed N. , Erdman Arthur G.
Published: March 2021

A new interactive computer graphics program (MKCIRCLES) has been developed to solve the following three-precision-position dyad synthesis tasks: (i) motion generation, (ii) path generation with prescribed timing and (iii) a new solution strategy for (a) motion generation for a user-specified range of the prescribed-timing angular displacements, and (b) path generation with prescribed timing for a user-specified range of the rotations of the floating link. The latter two cases address a problem that is encountered in linkage design; namely, the need to specify limits that certain variables may range through as opposed to specifying fixed values that constrain the design unnecessarily, thus increasing the total number of designs from which to choose. As a result of this new approach, two planar regions, representing all permissible dyad ground-pivot locations and all permissible dyad moving-pivot locations, are identified and plotted. The program uses the properties of the circle-point circles (K1-circles) and the center-point circles (M-circles) throughout the synthesis procedure. MKCIRCLES also allows the designer to define a region in which the ground-pivots are constrained to lie and determine the corresponding moving-pivot region (and vice versa). The program is shown to be a useful design tool and provides greater geometric and kinematic insight into the general three-precision-position synthesis problem.
A Direct Rotatability Criterion for Spherical Four-Bar Linkages
Authors: Ma R. , Gupta K. C.
Published: March 2021

The necessary and sufficient conditions for the full input rotatability in a spherical four bar linkage are proved. The direct criterion is: for all twist angles α in the range [0, π], the excess (deficit) of the sum of the frame and input twist angles over (from) π should, in absolute value, be greater than that for the coupler and follower twist angles; the difference between the follower and input twist angles, in absolute value, should be greater than that for the coupler and follower twist angles. Application of the direct criterion to full rotatability of other links are discussed and some variations in the form of the criterion are developed.
Performance Quality, Sensitivity, and Tolerance Specification of Mechanisms
Authors: Ting Kwun-Lon , Long Yufeng
Published: March 2021

By employing Taguchi’s concept to mechanism synthesis, this paper presents the theory and technique to identify a robust design, which is the least sensitive to the tolerances, for mechanisms and to determine the tolerance specification for the best performance and manufacturability. The method is demonstrated in finite and infinitesimal position synthesis. The sensitivity Jacobian is first introduced to relate the performance tolerances and the dimensional tolerances. The Rayleigh quotient of the sensitivity Jacobian, which is equivalent to Taguchi’s signal to noise ratio, is then used to define the performance quality and a sensitivity index is introduced to measure the sensitivity of the performance quality to the dimensional tolerances for the whole system. The ideal tolerance specification is obtained in closed form. It shows how the tolerance specification affects the performance quality and that the performance quality can be significantly improved by tightening a key tolerance while loosening the others. The theory is general and the technique is readily adaptable to almost any form and type of mechanical system, including multiple-loop linkages and mechanical assemblies or even structures.
Long-Dwell, Finite-Dwell Linkages
Authors: Alam Askari Badre , Strait D. A.
Published: March 2021

A new class of long-dwell, finite-dwell linkages has been discovered. This paper presents the design methodology for the new type of mechanisms using a dual stiffness element (buckling column). Fabrication of a first new long dwell mechanism working prototype has been completed. The experimental system is described and results of numerical and experimental models are compared. Simplification of these new mechanisms via introduction of flexible links and joints is discussed.
Effects of Payload on the Vibrational Excitation of Robot Manipulators During Motion
Authors: Tu Q. , Rastegar J.
Published: March 2021

The effects of payload mass, size, and end-effector holding location on the vibrational excitation of manipulators during motion are determined based on a new method, referred to as the trajectory pattern method. This is accomplished by examining the harmonic content of the actuating torques (forces) required for open-loop tracking of a selected trajectory pattern, the relative amplitude of each harmonic, and the energy input to the system by each harmonic. The simplest possible trajectory pattern for point to point motions with zero end point acceleration and jerk is employed as the basis for this study. It is shown that the amplitude of each harmonic is affected differently by the addition of the payload. The amplitudes change depending on the direction of motion and the location of the path of motion within the workspace of the manipulator. The harmonic content of the required actuating torques are not affected. The study provides information for planning paths of motion and synthesizing trajectories that are from the vibration point of view less sensitive to the payload. As an example, the effects of payload on a plane 2R manipulator are studied.
Computerized Design of Low-Noise Face-Milled Spiral Bevel Gears
Authors: Litvin F. L. , Zhang Yi , Handschuh R. F.
Published: March 2021

An advanced design methodology is proposed for the face-milled spiral bevel gears with modified tooth surface geometry that provides a reduced level of noise and has a stabilized bearing contact. The approach is based on the local synthesis of the gear drive that provides the “best” machine-tool settings. The theoretical aspects of the local synthesis approach are based on the application of a predesigned parabolic function for absorption of undesirable transmission errors caused by misalignment and the direct relations between principal curvatures and directions for mating surfaces. The meshing and contact of the gear drive is synthesized and analyzed by a computer program. The generation of gears with the proposed geometry design can be accomplished by application of existing equipment. A numerical example that illustrates the proposed theory is presented.
Analysis and Synthesis of the Dual Roller-Cam Mechanism
Authors: Chang Sun-Lai
Published: March 2021

A mechanism with two roller-cam pairs as its moving joints has been introduced. In such a mechanism, higher efficiency and longer operating life cycles are expected because of the absence of slippage in its moving joints. The kinematic analysis of this class of mechanisms has been performed. An equivalent geared five-bar mechanism has been utilized for the analysis of velocity. Several characteristics pertaining to this class of mechanisms, such as action angle, force equilibrium and singular position, have been discussed. The synthesis of this class of mechanisms with circular cam profiles has also been studied.
A Kinematic Method for Improving Motion Characteristics of Cam-Follower Systems
Authors: Yan Hong-Sen , Tsai M. C. , Hsu M. H. , Fong M. K. , Hsieh W. H.
Published: March 2021

A cam is often assumed to be operated at a constant speed in designing a cam-follower system. And, to improve the motion characteristics is to do a new design by finding an appropriate cam-profile. From the kinematic point of view, this paper presents an alternative approach to improve the motion characteristics by varying the speed of the cam. Design criteria for selecting suitable cam speed trajectories are provided. Examples are given to illustrate the design procedure and also to show the feasibility.