bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflections on a Clinical Approach to Engineering Design
Authors: Phillips J. R. , Gilkeson M. M.
Published: April 2021

A report on the operation and management of the 25-year old Engineering Clinic, a university-centered design program which incorporates sponsored industrial R & D into its engineering program. In the three-course design sequence, third and fourth year students practice engineering in team-organized projects under counsel by a professor and his counterpart industrial liaison. Twenty-five to thirty projects are conducted each year.
Formal Solution of N-Type Taguchi Parameter Design Problems With Stochastic Noise Factors
Authors: Michelena Nestor F. , Agogino Alice M.
Published: April 2021

The Taguchi method of product design is a statistical experimental technique aimed at reducing the variance of a product performance characteristic due to uncontrollable factors. The goal of this paper is to provide a monotonicity analysis based methodology to facilitate the solution of N-type parameter design problems. The obtained design is robust, i.e., the least sensitive to variations on uncontrollable factors (noise). The performance characteristic is unbiased in the sense that its expected value equals a target or specification. The proposed loss function is based on the absolute deviation of the characteristic with respect to the target, instead of the common square error approach. Conditions, like those imposed by monotonicity analysis, on the monotonic characteristics of the performance function are proven, despite the objective function is not monotonic and contains stochastic parameters. These conditions allow the qualitative analysis of the problem to identify the activity of some constraints. Identification of active sets of constraints allows a problem reduction strategy to be employed, where the solution to the original problem is obtained by solving a set of problems with fewer degrees of freedom. Results for the case of one uncontrollable factor are independent of the probability measure on the factor. However, conclusions for the multi-parametric case must take into account the characteristics of the probability space on which the random parameters are defined.
Tuning Parameters in Engineering Design
Authors: Otto Kevin N. , Antonsson Erik K.
Published: April 2021

In the design and manufacture of mechanical devices, there are parameters whose values are determined by the manufacturing process in response to errors introduced in the device’s manufacture or operating environment. Such parameters are termed tuning parameters, and are distinct from design parameters which the designer selects values for as a part of the design process. This paper introduces tuning parameters into the design methods of: optimization, Taguchi’s method, and the method of imprecision [8]. The details of the mathematical formulation, along with a design example, are presented and discussed. Including tuning parameters in the design process can result in designs that are more tolerant of variational noise.
CAD Systems and Cognitive Complexity: Beyond the Drafting Board Metaphor
Authors: Robertson David , Ulrich Karl T. , Filerman Marc
Published: April 2021

Computer-Aided Design (CAD) systems can and should support and enhance the product development process. Unfortunately, the benefits delivered by current systems have not met users’ expectations. We believe that CAD systems should be designed to minimize the cognitive complexity facing the engineer; CAD systems should be easy to use and should help the engineer manage design-related complexity. A series of propositions are developed which refine these ideas. To evaluate the central propositions, we constructed a prototype CAD system for the design of blanked and bent sheet metal parts. The user of the system is provided with a hand-held input device which interprets actions of the user’s hands as production operations on a CAD representation of the part. The user creates sheet metal parts by bending, stretching, pushing, and moving the input device. The system was demonstrated to engineers, engineering managers, and researchers, who provided ideas for future enhancements. Reactions to the demonstrations of the system have helped evaluate the concepts behind the system. Although we have used sheet metal as an example domain, we believe these ideas can be applied in other design contexts.
Computer-Automated Design of Aesthetic Injection Molded Products
Authors: Wallace David R. , Jakiela Mark J.
Published: April 2021

A model of the industrial design process for mass produced consumer products is proposed and described. The model can be used to design products subject to ergonomic, manufacturing, and aesthetic constraints. Injection molding is assumed as the primary manufacturing process for the artifacts designed. The four stages of the model, component organization, surface styling, product detailing, and graphical design are discussed. A computer-based implementation of the model is presented. As input to the system, users provide a selection of product components (e.g. speakers, displays, etc.) and choices for product attributes, including an aesthetic style. The system outputs a complete design of all visible surfaces of the product in the chosen style. An important result of the work is a verification of a basic method for capturing and imposing aesthetic styles on product designs.
Geometry-Based Index for Predicting Sink Mark in Plastic Parts
Authors: Beiter Kurt , Ishii Kosuke , Hornberger Lee
Published: April 2021

This paper describes the development of geometry-based indices that predict sink mark depth in injection molded parts. Plastic part designers need such indices to incorporate manufacturability concerns at the conceptual stage of design. These indices apply to several form features so engineers do not have to check different design rules for each geometry element. First, we propose a geometry-based sink index that can be used to predict sink mark depth as a function of process conditions such as packing pressure. Next, we explain how this relationship is identified through experiments. We also describe HyperDesign/Plastics, a Macintosh-based design aid that incorporates the sink index.
Design for Environmentability
Authors: Navinchandra D.
Published: April 2021

There is a growing interest in making products environmentally more compatible. While there is a need to make products and processes less toxic, to increase recyclability, and to reduce waste; we have to try to achieve environmental friendliness without compromising product quality. This approach to design has come to be called Green Engineering Design. The aim is to identify, develop, and exploit new technologies that can bolster productivity without costing the environment. The idea is to inject concerns about environmental friendliness into the design process; where, the assessment of environmental friendliness is based on a life-cycle view of the product. This includes the product’s manufacturing process, distribution, use, and final disposal. Our approach to green engineering design has two pans: (1) the development of special green indicators — measures of environmental compatibility, and (2) tools that use the green indicators to help designers assess, compare, and make design decisions.
Use of Functional Variants in Product Development
Authors: Hundal M. S.
Published: April 2021

The systematic design method calls for the preparation of a requirements list for the design problem, followed by development of a function structure. The functional description of a product is a description at an abstract level, in solution-neutral terms. At the functional stage different design possibilities can be explored by developing functional variants. Two major avenues for this are (a) subdividing functions (divergence), and (b) combining and eliminating functions (convergence). The latter can lead to simpler and cheaper designs through function integration and reduction, respectively. It is discussed with the help of industrial design examples.
Towards a Cooperative Design Methodology: Analysis of Sequential Decision Strategies
Authors: Krishnan Viswanathan , Eppinger Steven D. , Whitney Daniel E.
Published: April 2021

We envision a new class of methods, constituting what we call a cooperative design methodology, to support group decision making in design practice. As a first step, we model the cooperative design process as a multicriteria, multilevel decision problem and focus on understanding the relationships between design structure and decision strategies. In this paper, we present methods to characterize sequential decision strategies. We first introduce the notion of Quality Loss to quantify the loss of design freedom in the downstream stages of a sequential scheme. Towards identifying the sequence with the lowest quality loss (the “optimal sequence”), which is of practical significance in the design of time-critical products, we partition design variables into exclusive groups based on their connectivities. Next, the sensitivities and connectivities are combined to characterize invariant design decisions. Sufficient conditions, relating exclusive group structure to invariant decisions, are presented to reduce the complexity of identifying the optimal sequence. These ideas are illustrated using a dc motor design example.
Optimization of Design Utility
Authors: Thurston Deborah L. , Carnahan James V. , Liu Tiefu
Published: April 2021

Design optimization is often carried out with respect to a single objective, for example, weight or manufacturing cost. Weight, cost, quality and robustness are each important considerations in design evaluation. However, when the design process is completed, a design is evaluated with respect to its performance in all of these areas, and possibly others, in addition to mechanical design considerations.

The process of design should be driven from the very beginning by consideration of how the design artifact will ultimately be evaluated. We present a method for design analysis whose basic premise is that design analysis should be based on a rigorously determined multiple attribute design evaluation function. The evaluation function provides insight necessary to formulate a non-linear programming problem. A clear distinction is made between design attributes and design constraints. The objective function is maximization of utility. Explicit representations of relationships between decisions which designers make and resulting design performance in each of several attributes serve as constraints.

An illustrative example of automotive bumper beam design optimization is presented. By coupling the physical relationships between the design decision variable beam gauge and the attributes weight, deflection and cost, maximization of the worth of the design in terms of the best combination of these attributes is possible. The solution can be expressed in terms of elements of a design vector over which the designer has direct control.
An Intelligent Real Time Design Methodology for Catalog Selection
Authors: Bradley S. R. , Agogino Alice M.
Published: April 2021

An Intelligent Real Time Problem Solving (IRTPS) methodology is presented for catalog selection applications. A decision analytic approach is developed with the goal of assisting designers in making decisions during catalog selection that balance the cost of the limited resources consumed during the design process, such as the designer’s time, against the benefit to be derived from the utilization of those resources in terms of expectations of an improved design. This decision analytic approach is shown to complement other formal methods for design based on interval arithmetic and qualitative optimization, and a general methodology is proposed for performing catalog selection utilizing a combination of these methods. An example application to the selection of rolling element bearings is presented to clarify the methodology.
A Manufacturability Evaluation and Improvement System
Authors: Yannoulakis Nicholas J. , Joshi Sanjay B. , Wysk Richard A.
Published: April 2021

The increasing application of CAE has lead to the evolution of Concurrent Engineering — a philosophy that prescribes simultaneous consideration of the life-cycle design issues of a product. The Concurrent Engineering (CE) systems that have been developed so far have relied on knowledge bases and qualitative evaluations of a part’s manufacturability for feedback to the design engineer. This paper describes a method for developing quantitative indicators of manufacturability. Feature-based design and estimation of machining parameters are used for ascertaining a part’s manufacturing requirements. These requirements are then combined into indices which lead the designer to features that must be redesigned for improved manufacturability. This method is illustrated on a system for rotational machined parts: the Manufacturability Evaluation and Improvement System (MEIS).
Accelerating the Iterative Process in Design: An Experimental Evaluation of a Computer Based Expert Advisor
Authors: Starr Patrick J. , Stevenson Sylvia
Published: April 2021

This work explores whether the assistance provided by an Expert Advisor System actually allows a knowledgeable designer to obtain results faster when engaged in a complex trial and error search process. The process is the adjustment of parameters of a discrete event simulation of a manufacturing system in order to achieve certain design specifications. Designed experimentation is employed with human subjects performing tasks with and without the Expert Advisor.
End Point Non-Uniqueness in Labeled Interval Calculus Operations
Authors: Bains Navjoat S. , Boettner Daisie D. , Ward Allen C.
Published: April 2021

Designers must often reason quantitatively about sets of artifacts under sets of operating conditions. The labeled interval calculus (LIC) is a formal reasoning mechanism for such inferences. This paper discusses its fundamental operations in greater detail than previous publications. In particular, it provides proofs for a new and more efficient computation mechanism of these operations. Further, it details the effect of interval end point non-uniqueness not dealt with earlier, identifying the need for, and defining new operations.
In Pursuit of a Design Mathematics: Generalizing the Labeled Interval Calculus
Authors: Habib Walid , Ward Allen C.
Published: April 2021

The Labeled Interval Calculus (LIC) is a formalism for reasoning about sets of design possibilities. Examples include toleranced objects, abstract descriptions involving many possible instantiations, and varying operating conditions. It has been successful in a “mechanical design compiler”, which accepts schematics and specifications and returns catalog numbers for optimal implementations. The LIC at present operates on monotonic algebraic equations and intervals of real values, but it now appears possible to generalize it to address arbitrary types of mathematical sets and relationships. The resulting family of formalisms is expected to be useful in design by feature and other design programs.
The Design Process As Managing an Open System of Information
Authors: Starr Patrick J.
Published: April 2021

Design and planning take place in an environment of growing information. This work will explore the concept that conducting a design project can be viewed as managing an open system which exchanges information with an environment. Analogies are drawn with physical and biological systems which exchange matter and energy with their surroundings. Through the use of graphical representation, we will illustrate how these areas contribute to a framework for perceiving and managing the evolutionary process of design and planning.
Design Methodologies for Computer Architecture Specifications
Authors: Carothers Jo Dale
Published: April 2021

The importance of the study of design theory and methodologies has become apparent in all disciplines of engineering. In particular, if the computer industry is to advance at the rate of improvements in semiconductor technology, then better methods must be developed for designing and verifying computer architectures. The field of computer-aided design (CAD) has provided tools and analysis techniques for use in this area. However, the vast majority of CAD systems require a formal, complete specification of the computer’s design as input. Creating such a complex specification is itself a very difficult, time-consuming task. In reality this is truly the “design” phase and is usually assumed already complete by CAD systems. The design, including performance/cost trade-offs and verification, of architecture specifications is the subject of this research.
Subdivision of Triangular Bézier Patches Into Rectangular Bézier Patches
Authors: Iino Kenji , Wilde Douglass J.
Published: April 2021

We propose an algorithm to decompose a triangular Bézier patch (integral or rational) into three non-degenerate rational rectangular Bézier patches of the same degree. This allows the treatment of a triangular patch as a collection of three rational rectangular patches.
Synthesis of Curved Surfaces Using the Parametric B-Spline Tensor Product
Authors: Tsay D. M. , Chen C. M.
Published: April 2021

A general, computational geometry design procedure for the synthesis of curved surfaces is presented. The method applies the parametric B-spline (basis spline) tensor product to interpolate prescribed geometrical constraints, even when the set of constraints is sizable. Using the well-developed mathematical tool, B-spline functions, the method is very dependable, versatile, and numerically stable for the design of mechanical parts with complex shapes. Since a curved surface can be represented by a formula of B-spline tensor product, the approach enables the coordinates required for analysis or manufacturing to be easily generated. Typical examples for the synthesis of curved surfaces are given to illustrate the application of the approach.
Computer Aided Geometric Design of Motion Interpolants
Authors: Ge Q. J. , Ravani B.
Published: April 2021

This paper studies continuous computational geometry of motions and develops a method for Computer Aided Geometric Design (CAGD) of motion interpolants. The approach uses a mapping of spatial kinematics to convert the problem of interpolating displacements to point interpolation in the space of the mapping. To facilitate the point interpolation, the previously non-oriented mapping space is made orientable. Methods are then developed for designing spline curves in the mapping space with tangent, curvature and torsion continuities. The results have application in computer animation of three dimensional objects used in computer graphics, computer vision and simulation of mechanical systems.
Rational Polynomial Surface Intersections
Authors: Kriezis G. A. , Patrikalakis N. M.
Published: April 2021

This paper presents a new algorithm for the computation of the intersection of two rational B-spline surface patches. This algorithm is based on the computation of significant points of the intersection in the parameter space of one of the patches using direct numerical techniques; partitioning of the intersection domain at these points; tracing of the resulting intersection segments using subdivision and Newton or marching techniques; and verification of computation of all intersection branches using convexity properties of the two surfaces and their partial derivatives.
Synthesis and Analysis of Geometric Design Models Using Tree-Structured Relations
Authors: Tsai P. L. , Chieng Wei-Hua , Hoeltzel David A.
Published: April 2021

A methodology for the synthesis and analysis of a relational geometric design model, based on a mapping between geometric nodes (points) on the object which are stored in a tree structure and physical dimensions, is presented in this paper. For this methodology, the relations between geometric nodes are restricted to both translation and rotation. An algorithm has been implemented based on this methodology that allows a designer to freely synthesize and analyze geometric relations among key physical dimensions of the object, while the management of the underlying parameterized relational geometric data occurs automatically.
A Fast Wireframe Display Algorithm for Hidden Surface Removal in Constructive Solid Geometry
Authors: Jeng Shyr-Long , Chieng Wei-Hua , Hoeltzel David A.
Published: April 2021

A fast algorithm for rendering three dimensional geometry as wireframes is developed. The algorithm employs a constructive solid geometry (CSG) model as its underlying geometric representation scheme, set membership classification for the removal of non-boundary lines, and a finite-point backward ray tracing method for hidden line removal. By eliminating conventional polygon surface approximation and its associated surface topology representation, requiring high information overhead, the algorithm demonstrates speed and simplicity. The primary purpose of the algorithm is for expeditious real-time graphical simulation, particularly for interactive design. The algorithm demonstrates overall time complexity of O(n2 h*2), where n denotes the total number of geometric primitives, and h* denotes the total number of boundary edge segments. Desirable side effects associated with the use of set membership classification include the ability to generate NC machine instructions and the detection of object interference for collision avoidance during the simulation of manufacturing processes. Examples demonstrating the visualization of 3-D mechanical components are included.
The Shortest Path for a Point Passing Through Obstacles Represented by Quadratic Curves
Authors: Blechschmidt James L. , Wu J. L.
Published: April 2021

In this paper we present an algorithm for the search of the shortest path through a set of obstacles approximated by circles and ellipses. A set of heuristics is developed to eliminate obstacles that do not affect the search for the shortest path. The A algorithm is used during the path generation phase to direct work toward the estimated shortest path. Algebraic techniques are used for computing a set of pseudo vertices since no natural vertices exist with the algebraic representation of the obstacles. Examples are given to demonstrate the techniques developed.
Synthesis and Steady State Analysis of High-Speed Elastic Cam-Follower Linkages With Concentrated Masses: Part I — Theory
Authors: Liu Hsin-Ting J. , Flugrad Donald R.
Published: April 2021

A cam driving a lumped inertia through a massless, elastic, slider-crank follower linkage with two concent rated masses located at the pin joints is considered. An iterative procedure taking the elasticity, damping, and changing geometry of the linkage into account is developed for synthesizing the cam profile to produce a desired output motion at a given design speed. The steady state solutions for the inhomogeneous, periodic, linear, ordinary differential equations are solved numerically by Hsu’s method.
Synthesis and Steady State Analysis of High-Speed Elastic Cam-Follower Linkages With Concentrated Masses: Part II — Steady State Analysis
Authors: Liu Hsin-Ting J. , Flugrad Donald R.
Published: April 2021

The responses for different design and simulation conditions, including various speed and damping ratios, are investigated for an elastic cam-follower system discussed in Part I. The location of a single dominant pair of characteristic multipliers of the inhomogeneous periodic linear system is found to have significant influence on the steady state response.
The Incorporation of Arc Boundaries and Stick/Slip Friction in a Rule-Based Simulation Algorithm for Dynamic Mechanical Systems With Changing Topologies
Authors: Han Inhwan , Gilmore Brian J. , Ogot Mandara M.
Published: April 2021

Many dynamic mechanical systems, such as parts-feeders and percussive power tools, are described by equations of motion which are discontinuous. The discontinuities result from kinematic constraint changes which are difficult to foresee, especially in presence of impact and friction. A simulation algorithm for these types of systems must be able to algorithmically predict and detect the kinematic constraint changes without any prior knowledge of the system’s motion. This paper presents a rule-based approach to the prediction and detection of kinematic constraint changes between bodies with arc and line boundaries. A new type of constraint change, constraint exchange, is characterized. When arc contact exist, stick/slip friction is the difference between pure rolling and rolling with slip. Therefore, stick/slip friction is included in the algorithm. A force constraint is applied to the equations of motion when additional kinematic constraints due to friction would render the coefficient matrix singular. The efficacy of the rule-based simulation algorithm as a design tool is demonstrated through the design and experimental validation of a parts-feeder. The parts-feeder design is validated through two means; 1). a frame-by frame comparison of simulation results with the part motion recorded by high speed video and 2). actual testing.
The Formulation of Kinematic Constraints in Design-Oriented Machine Dynamics
Authors: Saha Subir Kumar , Angeles Jorge
Published: April 2021

In the realm of the dynamic analysis of machinery for design purposes, the determination of non-working constraint forces, which do not appear in simulation studies, is of the utmost importance. The said forces can be readily computed if suitable kinematic constraints are available. In this paper, a formulation of kinematic constraints is adopted, that pertains to the natural orthogonal complement method, introduced elsewhere, for the dynamic modeling of mechanical systems. This formulation is illustrated with several examples.
Synthesis and Steady State Analysis of High-Speed Elastic Cam Follower Linkages by a Finite Element Method
Authors: Liu Hsin-Ting J. , Flugrad Donald R.
Published: April 2021

A cam driving a lumped inertia through an elastic slider-crank follower linkage with a curved beam coupler is considered. An iterative procedure utilizing the finite element method developed by Midha et al. (1978) is used to synthesize the cam profile to produce a desired output motion at a given design speed and damping coefficient. Nonlinear terms are neglected producing inhomogeneous. periodic, linear, ordinary differential equations. Response of the synthesized linkages are simulated and found to be satisfactory at the design conditions.
Computational Geometry for Optimal Workpiece Orientation
Authors: Haghpassand Khorssand , Oliver James
Published: April 2021

Workpiece orientation is formulated as an optimal design problem based on a discrete approximation of design surface geometry and the kinematic capabilities of the process machine tool. The primary process application addressed is three- and four-axis numerically controlled (NC) milling, although the techniques presented may be applied to machines with more general articulation. Recent developments in applied spherical geometry are employed to formulate a nonlinear optimization problem. For three-axis milling applications, by assigning a weight to each surface normal of the discrete model corresponding to the actual area it represents, the orientation is optimized such that the angle between the normals and the milling tool axis is minimized. This formulation is augmented, for four-axis milling, to incorporate limitations of the rotational degree of freedom into the optimization formulation.
Pseudoedge: A Hierarchical Skeletal Modeler for the Design of Structural Components
Authors: Bonner David L. , Jakiela Mark J. , Watanabe Masaki
Published: April 2021

A new design model for the creation of mechanical components has been developed. In this model, the shape is expressed by its areas of prominence or maximum curvature, for which we use the term pseudoedges. In terms of traditional design, these represent both fillet, chamfer and intersection lines, and more general shape features. The pseudoedges of the model combine with a skeletal shape that is used as a starting form, thereby creating a hierarchy of geometric dependencies that affords both global and local control. The surface is represented by a quilt of parametric Bezier patches, with tangent plane continuity everywhere and only certain isolated singularities. Considerable degrees of deformation are possible, with predictable control and at small computational expense; there is no need for computation of intersections or parameter space trimming of patches.
Motion Planning in Plant CAD Systems
Authors: Kondo Koichi , Ohtomi Koichi
Published: April 2021

This paper discusses a general and efficient method for solving the motion planning problem defined as checking the existence of a collision-free path among known stationary obstacles, and also presents its application to a plant CAD system. The basic approach taken in this method is to restrict the free space referred to in path searching and to avoid executing unnecessary collision detections. The configuration space is equally quantized into cells by placing a regular grid, and two new search strategies which enumerate restricted cells are introduced for realizing this method. One is a local strategy which enumerates free space cells only along the boundary of the free space in the configuration space. Another is a global strategy which finds the outer boundary of the free space. This method has been actually implemented and has been applied to an example in a nuclear power plant.
Automated Linearization of Nonlinear Coupled Differential and Algebraic Equations
Authors: Vanderploeg Martin J. , Trom Jeff D.
Published: April 2021

This paper presents a new approach for linearization of large multi-body dynamic systems. The approach uses an analytical differentiation of terms evaluated in a numerical equation formulation. This technique is more efficient than finite difference and eliminates the need to determine finite difference pertubation values. Because the method is based on a relative coordinate formalism, linearizations can be obtained for equilibrium configurations with non-zero Cartesian accelerations. Examples illustrate the accuracy and efficiency of the algorithm, and its ability to compute linearizations for large-scale systems that were previously impossible.
Generating the Swept Area of a Body Undergoing Planar Motion
Authors: Ling Zhi-Kui , Chase Thomas R.
Published: April 2021

The swept area of a two dimensional object undergoing motion in its plane of definition is the union of the area occupied by the object at all positions during the motion. A methodology for determining a close approximation to an exact swept area for a known arbitrary motion is developed here. The methodology has use for preventing interference between links of a planar mechanism during synthesis.

Criteria for determining individual points falling on the border of the swept area from the body during any instant of the motion are derived from envelope theory. Points on the swept area boundary are determined at the initial position of the sweeping body for computational efficiency. The swept area is constructed from these points plus sections of the border of the moving body at select positions. Overlap of the swept area onto itself is handled by splitting the overall swept area into a small number of individual swept areas free of overlap. An eleven-step swept area algorithm is clarified with an example.
Automatic Surface Generation From Wireframe Data Enhancements
Authors: Parameswaran Ramesh , White Phillip R.
Published: April 2021

This paper presents several enhancements to existing methods of converting wireframe CAD models to surface representations. Existing methods consider only polyhedral objects. In these methods, closed loops of edges in the wireframe, which define the boundaries of planar surfaces, are first detected by a combination of topological and geometric techniques. The regions bounded within these edges are then approximated by a number of planar polygons. Enhancements described in this paper permit the algorithms to be extended to wireframes that describe objects with curved surfaces and surfaces with holes. An approach for tesselating curved surfaces is also described. With these enhancements, conversion methods can then be applied to arbitrary wireframes without imposing restrictions on the edges or surfaces that comprise the wireframes.
Analysis of Axisymmetric Piezoceramic Microactuators and Designs for Fluid Control Applications
Authors: Kosaraju Chenchiah B. , Naganathan Nagi G.
Published: April 2021

A finite element model has been developed to analyze axisymmetric piezoceramic actuators with arbitrary internal poling. The finite element methodology is verified by demonstrating a favorable agreement of the numerical results obtained in this study with results published for an ink-jet printer application. In addition, design of a piezoceramic nozzle is investigated with both single layer and stacked axisymmetric piezoceramic geometries. Such piezoceramic micronozzles can be effectively employed in sensitive low-displacement valve applications such as speed control of jet engines.
Cam Motion Synthesis Using Cubic Splines
Authors: Yoon Kooyoung , Rao S. S.
Published: April 2021

The application of minimum norm principle, similar to the principle of minimum potential energy, is presented for the general synthesis of cam motion. The approach involves the use of piecewise cubic spline functions for representing the follower displacement. The cubic splines are more convenient and simpler to use compared to general spline functions and also result in smaller peak acceleration and jerk due to the application of the minimum norm principle. A general procedure is presented for application to any cam-follower system. The effectiveness of the approach is illustrated by comparing the results given by the present method with those given by other approaches for a disk cam-translating follower.
Numerical Analysis of the Kinematic Dexterity of Mechanisms
Authors: Yang Feng-Cheng , Haug Edward J.
Published: April 2021

A broadly applicable approach for numerical analysis of kinematic working capability of mechanisms is presented. Composite workspaces are introduced to represent position and orientation capabilities of mechanisms, both individually and together. Numerical methods for solving systems of kinematic constraint equations, using a moving-frame algorithm, and equations that characterize the workspace boundary are developed. Two analytic methodologies, comparison and incorporation methods, are presented to determine whether the workspace of a mechanism satisfies design requirements. A computer program for workspace analysis that incorporates a numerical solver and computer graphics for visualization on a high speed graphics workstation is outlined. The feasible positioning space of a Stewart platform that is subject to orientation constraints is computed, to illustrate the use of this approach and the associated computer program.
An Automated Procedure for the Maximization of the Mechanical Advantage of Planar Mechanisms
Authors: Ogot Madara M. , Gilmore Brian J.
Published: April 2021

This paper presents an automated procedure for the maximization of the mechanical advantage (M) of planar mechanisms. First, the classical definition of mechanical advantage is extended to include multiple-input, multiple-output mechanisms, thus allowing the maximization of the mechanical advantage of multiple-input mechanisms, a task which was hitherto not possible. A knowledge-based approach is utilized to perform a sensitivity analysis from which the mechanism parameters are automatically altered. In this manner the human designer is removed from the optimization loop. Several examples are presented which illustrate the versatility and generality of this approach.
Dynamic Modeling of Planar Closed-Loop Kinematic Chains Based on an Instantaneously Unconstrained Energy Equivalence Scheme
Authors: Lai Chieng-Liang , Chieng Wei-Hua , Hoeltzel David A.
Published: April 2021

Traditional Euler-Lagrange methods for the dynamic analysis of kinematic chains require repetitive calculation of the kinematic constraints. This becomes very inefficient as the number of joints (or kinematic constraints) increases. This paper presents a new approach for the dynamic analysis of constrained dynamic systems. The salient feature of this approach is the separation of the kinematic analysis from the dynamic analysis. Following this separation, the resulting dynamic system becomes instantaneously unconstrained. While the discussion is mainly oriented towards the analysis of planar mechanisms, the model can be readily extended to the analysis of spatial mechanisms. A methodology for computer-aided symbolic derivation of the dynamic equations based on this approach is presented, and a numerical example which demonstrates a significant reduction in computing time for the dynamic analysis of a planar mechanism, as compared with conventional solution approaches, is provided.
Computer Aided Part Design Based on Standard Component Interface Geometry
Authors: Johannesson H. L.
Published: April 2021

In this paper it is suggested how an integrated computer based system for part design can be built. The main issue is how to automatically provide geometry data, determined by selected interacting standard components, to the used CAD-system. This kind of function determined geometry is in the paper called “interface geometry.”

The key component in the integrated computer program system is the standard component data base. This data base contains a parametric model of the standard component and its “interface geometry”. Parameters necessary as input data both to component performance analysis programs and geometry creation programs, are all included in the model.

The integrated program system consists of a data base, managed by a data base management system, application programs for component performance analysis and selection, and a conventional CAD-system. In order to make these different parts communicate, certain interface programs, both CAD-system dependent and independent, have been developed.
Integrated Optimization in Computer-Aided Design and Manufacturing of Machine Products Based on Shape Descriptions of Contact Surfaces
Authors: Yoshimura Masataka , Takeuchi Atsushi
Published: April 2021

This paper proposes a method for integrating CAD and CAM in which both maximization of the product performance and minimization of the product manufacturing cost are sought. In order to obtain effectively and efficiently the optimum decision variables for the integrated product design and process design, a method for describing machine-parts shapes is first developed with main consideration being given to the description of the contact surfaces. Then, a multiphase decision making method using those data is constructed in which the decision making process is divided into three phases. The shapes, materials, and manufacturing methods of machine parts are then determined in steps according to multi-phase processes. Finally, the proposed methods are applied to the design of an industrial robot for demonstrating the effectiveness of the methods.
Sequential vs. Concurrent Formulations for the Synthesis of Engineering Designs
Authors: Karandikar H. M. , Rao J. , Mistree F.
Published: April 2021

Modeling and gaining an understanding of the interaction between information from design and from manufacturing is an important step in developing techniques and methods for concurrent engineering. In this paper, the role of optimization techniques in the product development process in a concurrent engineering framework is examined. Through arguments based in optimization theory, it is demonstrated that a concurrent approach to designing for manufacture problems is superior to a sequential one. By extension, this applies to designing for other life-cycle processes. Results which illustrate the point are presented from a comprehensive, non-textbook case study in design using composite materials and dealing with the integration of analysis, dimensional synthesis, and manufacturing. The case study is tackled by using Decision Support Problems. The focus in the paper is on understanding the ramifications of considering life-cycle processes concurrently.
Analysis and Optimal Synthesis of the RSCR Spatial Mechanism
Authors: Ananthasuresh G. K. , Kramer Steven N.
Published: April 2021

The closed form solution of the analysis of the RSCR (Revolute-Spherical-Cylindrical-Revolute) spatial mechanism is presented in this paper. This work is based on the geometric characteristics of the mechanism involving the following three cases: the cone, the cylinder and the one-sheet hyperboloid. These cases derive their names from the nature of the locus of the slider of the linkage as viewed from the output side. Each case is then treated separately to develop a closed form, geometry based analysis technique. These analysis modules are then used to optimally synthesize the mechanism for function, path and motion generation problems satisfying precision conditions within prescribed accuracy limits. The Selective Precision Synthesis technique is employed to formulate the nonlinear inequality constraints. These constraints along with an objective function and other constraints are solved using the Generalized Reduced Gradient method of optimization. In addition, the use of mobility charts is used to aid the designer in making a judicious choice for the initial design point before invoking the optimization method. The determination of the transmission angle for the RSCR mechanism is also described and numerical examples for function, path and motion generation are also included. This new closed form method of analysis based on geometric characteristics is computationally less intensive than other available techniques for spatial mechanism analysis and helps in the visualization of the physical mechanism; something that is not possible with most vector and matrix methods.
Experimental Study of Cardan Joint Dynamics
Authors: Fischer Ian S. , DeWaal Johannes K.
Published: April 2021

An experiment has been conducted indicating invalidity of the assumption of negligible intermediate-joint axial forces in Cardan joint (universal joint) dynamic analysis. It has been observed that increased driveline torque induces the radially-inward deflection of the yoke arms of a Cardan joint, while increased speed will deflect the yoke arms outward. Some suggestions are given to optimize Cardan joints for high torque or high speed.
A Closed-Form Formalism for Controlled and Hybrid Rigid/Elastic Multibody Systems: Part I — Formulation
Authors: Lieh Junghsen , Haque Imtiaz
Published: April 2021

A new formalism leading to closed-form formulation of equations for controlled elastic multibody systems is presented. The method is derived from the virtual work principle and includes the effects of a moving base and rigid body dynamics. The elastic members are treated as Euler-Bernoulli beams and the assumed-mode method is adopted. The equations of motion are expanded in a closed form with a minimum set of variables using the generalized coordinate partitioning and a Jacobian matrix expansion. The inertia matrix, nonlinear coupling vector, generalized force vector and other terms containing the velocity and acceleration effects of a moving base are formulated separately. The formalism facilitates matrix computations and is very suitable for symbolic processing. The method is very systematic and general and can be applied to a multibody system subject to control and constraint conditions. Derivation of the formalism is presented in part I of the article, and symbolic implementation and application of the formalism to various elastic mechanical systems are presented in part II.
A Closed-Form Formalism for Controlled and Hybrid Rigid/Elastic Multibody Systems: Part II — Symbolic Implementation and Applications
Authors: Lieh Junghsen , Haque Imitiaz
Published: April 2021

A program is developed on a DECstation using the symbolic language MAPLE which generates the equations of motion in a closed form and reduces the system order symbolically. A procedure that can make symbolic simplification and linearization is provided. The integration of shape functions is performed symbolically. Both nonlinear and linearized equations of motion with control are established in FORTRAN format. Several models including an elastic vehicle with active suspensions, an elastic robotic manipulator and an elastic slider-crank mechanism with both joint and structural flexibility are generated. Numerical simulation for the active vehicle model using an optimal control strategy is presented. The effect of active suspensions on vehicle and structural vibrations is briefly discussed. A comparison between the nonlinear and linearized robot models is given. Simulation results of the slider-crank mechanism are also presented.
Modeling of Flexible Bodies for Dynamic Analysis of Multi-Body Dynamic Systems Using Ritz Vectors
Authors: Wu Henry T. , Mani Neel K.
Published: April 2021

Vibration normal modes and static correction modes have been previously used to model flexible bodies for dynamic analysis of mechanical systems. The efficiency and accuracy of using these modes to model a system depends on both the flexibility of each body and the applied loads. This paper develops a generalized method for the generation of a set of Ritz vectors to model flexible bodies for dynamic analysis of multi-body mechanical systems. The Ritz vectors are generated using the distribution of dynamic loading on a flexible body. Therefore they form the most efficient vector basis for the spatial distribution of the loadings. The Ritz vectors can be re-generated when the system undergoes significant changes of its configuration and the regeneration procedure is inexpensive. The combinations of vibration normal modes and the proposed Ritz vectors thus form more efficient and accurate vector bases for the modeling of flexible bodies for dynamic analysis.
A Hybrid Integration Scheme for Simulation of Controlled Multibody Mechanical Systems
Authors: Lin Shih-Tin , Lance George M.
Published: April 2021

Simulation of a controlled multibody mechanical system, with a nonstiff mechanical subsystem and a stiff control subsystem, usually suffers from long run time. In this paper, a hybrid integration scheme is proposed to overcome this difficulty. The hybrid integration scheme consists of two parts: a nonstiff integration algorithm for the mechanical subsystem and a stiff integration algorithm for the control subsystem. A double pendulum driven by two AC motors and a backhoe mechanism driven by three hydraulic actuators are used to demonstrate the computational efficiency of the proposed integration scheme.
The Trajectory Analysis of Bevel Planetary Gear Trains
Authors: Lin Chen-Chou , Tsai Lung-Wen
Published: April 2021

In this paper, the trajectory of bevel planetary gear trains has been studied. The parametric equations of trajectory are derived. It is shown that the trajectory generated by a tracer point on the planet of a bevel planetary gear train is analogous to that of a spur planetary gear train. Two cases, gear ratio equal to one and two, are presented in detail including the geometric description, plane of symmetry, extent of trajectory, number of nodes (cusps) and their locations. The criteria for the existence of cusps are verified algebraically, and interpreted from geometrical point of view.
The Design and Analysis of Cam Profiles Using Algebraic Functions
Authors: Blechschmidt James L. , Lee Chung-Hsing
Published: April 2021

A new method for the design and analysis of cam profiles is developed and demonstrated in this paper using algebraic functions in two variables. A technique for the construction of the cam profile directly without using the lift curve is developed. The basis for this analysis is the use of Boolean operators in algebra using a form of algebraic function called the defining function. Using simple quadratic curves such as circles, ellipses, and slabs, more complicated cam profiles are constructed using the Boolean operators of union, intersection, and difference. The resulting closed algebraic curve is converted to the standard implicit form for follower analysis. We show that cam profiles using constraints on the lift at a specific angular rotation can be developed. Examples of all the operations are demonstrated.