bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual Interaction in Acoustic-Structural Analysis of Automobiles
Authors: Gaddipati Vijoy , Vance Judy M. , DeVries Richard
Published: March 2021

This paper describes a graphical technique used for investigating the effects of structural design changes on the sound pressure levels generated in an automobile compartment. Low frequency noise in the passenger compartment (in approximately the 20–85 Hz frequency range) is of primary interest, and particularly that noise which is generated by the structural vibrations of the wall panels and various other smaller parts of the compartment. A designer faced with reducing the noise levels at various frequencies typically has several hundred design variables as candidates for change. This paper describes a computer interface that facilitates understanding of the effect various design changes have on the noise levels. This interface allows the designer to investigate the design space to determine which variables hold the most promise for achieving the objectives of noise reduction and allows the designer to set targets or constraints, to a desired confidence level, using the sensitivity information of these design variables. The design targets set in this manner are then input to an optimization algorithm which solves for the optimized sound pressure level.
A Robotic Software Developed Using Object-Oriented Design
Authors: Nesnas Issa A. D. , Stanisic Michael M.
Published: March 2021

Due to its inter-disciplinary nature, robotic design often involves the integration of various complex system constituents. As a result, a means to manage this complexity becomes highly desirable, if not essential. The use of object-oriented design and programming is one such means, whereby the system is decomposed into layers of object model hierarchies. The work presented here is part of a project that involved the design of a vision based robot system for planar path tracking. The object-oriented design and decomposition of the robot system software will be presented. The hierarchies of the system’s data abstractions will be analyzed and some of the advantages of using object-oriented techniques will be illustrated through simplified versions of the system’s abstractions. Examples on the concepts of encapsulation, inheritance, polymorphism, and single typing will also be discussed. The use of object-oriented programming not only provides extendable and reusable software, it also provides a better and more efficient means for software development.
MDL: A Methodology Description Language in a CAE Integration Environment
Authors: Wang Nanxin , Cheng Jie
Published: March 2021

A methodology description language (MDL) has been designed for the rapid integration of CAE programs in order to automate complex engineering methodologies. Based on this language, an integration environment has been developed, which includes a representation scheme for methodology process flow and data flow, and a control scheme for methodology process scheduling, monitoring, and potentially, diagnosis. The blackboard technique has been adopted in the implementation of the control scheme. This approach has now been tested in several projects to prototype engineering methodologies involving multiple CAE analysis programs. It is anticipated that full implementation and deployment of this approach inside Ford Motor Company will enable the rapid prototyping of complex engineering methodologies for exploration, as well as optimization, of product designs and vehicle control strategies. Widespread use of these results within the Ford product development process will be a key enabler to improving product quality through including more up-front CAE analysis of vehicle components and systems while still achieving Fast Cycle Time goals.
Rod Design: A Concept to Production Connecting Rod Design System
Authors: Chau Eric L.
Published: March 2021

A Concept to Production Parametric Design Environment for connecting rod design is described. The system utilizes state of the art knowledge based engineering, constraint based reasoning, computer aided engineering (CAE), design (CAD), and manufacturing (CAM) technology to achieve 80% lead time reduction on prototype parts with similar lead time reductions possible on production parts.
Optimization-Based Design of a Leg Mechanism via Combined Kinematic and Structural Analysis
Authors: Shieh W. B. , Azarm S. , Tsai L. W. , Tits A. L.
Published: March 2021

We study a recently proposed compound two degrees of freedom planar leg mechanism consisting of a four-bar linkage and a pantograph. In this mechanism, one degree of freedom is used for normal walking to provide an ovoid path which emulates that of humans while the other is used only when necessary to walk over obstacles. Potential advantages of such a compound mechanism are fast locomotion, minimal energy loss, simplicity in controller design, and slenderness of the leg. To exploit these to the fullest, a multiobjective optimization-based design problem formulation is proposed with the following four design objectives: (i) minimum leg height, (ii) minimum of the maximum joint forces, (iii) minimum leg mass, and (iv) minimum energy loss for a walking cycle. In addition, this problem formulation takes into account a combination of mechanism requirements and structural requirements. Several tradeoff solutions are obtained using the Consol-Optcad interactive optimization-based design package.
Statistical Verification of Conformance to Geometric Tolerance
Authors: Kurfess Thomas R. , Banks David L.
Published: March 2021

Modern coordinate measurement machines have provided industry with new tools for inspecting complex parts. This paper develops statistical procedures that complement these inspection methods, and it ties the conformance problem into the hypothesis testing formalism of conventional statistics. Also, the paper suggests strategies for efficient sampling of the part surface, and an implementation of the usual decision-theoretic formulation of the tradeoff between false acceptance and false rejection of part geometries. These ideas are illustrated through the analysis of real and simulated data for perfect and imperfect cylinders.
An Effective Method for Modelling Flexible Surfaces of Cloth Objects
Authors: Zhao Y. F. , Tan S. T. , Wong T. N.
Published: March 2021

In this paper a method for modelling the deformation of flexible objects such as cloth is presented in which the physical analysis can be imported into the geometric simulation. The geometric representations as well as the physical properties of flexible objects are considered. A so-called basic configuration and a constraint finite element method are given to improve previous methods for modelling flexible objects. The basic configuration is a primitive 3-D surface of a flexible object, and the constraint finite element method is a special finite element method with respect to the constraint conditions of the deformed flexible objects. The basic configuration of a deformed flexible surface can be directly obtained from its initial 2-D shape by using some control points and curves. Subsequently, according to the geometric constraint conditions of deformation, the basic configuration is adjusted to a satisfactory flexible surface by the constraint finite element method.
Generating and Flattening of Developable Surfaces
Authors: Gan M. C. , Tan S. T. , Chan K. W.
Published: March 2021

In this paper, methods for generating and flattening developable surfaces by means of two given directrix curves have been investigated. By finding the two end points of every generatrix, a developable surface may be formed. Such a developable surface may be flattened by rotating part of the surface about a generatrix. A new approach based on the principle of geodesic curve length preservation for flattening developable surfaces is also introduced. In this technique, an algorithm for evaluating the geodesic curvature of a point of a curve that lies on a surface is utilized.
Geometric Decompostion and Structural Shape Modification for Turbomachinery Blades
Authors: Hines Brian D. , Oliver James H.
Published: March 2021

An efficient and precise method is presented for the generation of turbomachinery blade models in nominal configuration, i.e., the “cold-shape” given the blade geometry at operating conditions, i.e., the “hot-shape.” The shape correction technique has two main components: a preprocessor that generates a plate finite element model of the hot-shape geometry, and postprocessor that performs the blade shape correction. The preprocessor decomposes the hot-shape blade surface model into a mean camber surface and an associated set of thickness functions. A plate finite element mesh is generated on the resulting mean camber surface. The finite element model is used as input for specialized analysis software for cold-shape correction which provides displacements due to unloading the blade. The postprocessor constructs the nominal cold-shape blade model in two steps. First, the nodal deflections are applied to the hot-shape finite element model to generate a cold-shape mean camber surface. Then the original hot-shape thickness functions are applied to the cold-shape mean camber surface to generate characteristic blade section curves which are lofted to define the cold-shape blade model. Several examples of turbomachinery blades in their hot-shape and resulting geometry are presented to demonstrate the capabilities of the technique.
Feature Recognition by Volume Decomposition Using Half-Space Partitioning
Authors: Shen Yan , Shah Jami J.
Published: March 2021

A volume decomposition method called minimum convex decomposition by half space partitioning has been developed to recognize machining features from the boundary representation of the solid model. First, the total volume to be removed by machining is obtained by subtracting the part from the stock. This volume is decomposed into minimum convex cells by half space partitioning at every concave edge. A method called maximum convex cell composition is developed to generate all alternative volume decompositions. The composing sub volumes are classified based on degree of freedom analysis. This paper focuses on the first part of our system, i.e., the volume decomposition. The other part of the work will be submitted for publication at a leter date.
An Efficient Strategy for the Robust Optimization of Large Scale Nonlinear Design Problems
Authors: Ramakrishnan Balaji , Rao S. S.
Published: March 2021

The application of the concept of robust design, based on Taguchi’s design philosophy, in formulating and solving large, computationally intensive, nonlinear optimization problems whose analysis is based on a linear system of equations is investigated. The design problem is formulated using a robust optimization procedure that utilizes the expected value of Taguchi’s loss function as the objective. An efficient solution scheme that uses approximate expressions for the gradients and employs a fast reanalysis technique for their evaluation is introduced. This approach is validated by solving a simple minimum cost welded beam design problem; where the dimensions of the weldment and the beam are found without exceeding the limitations stated on the shear stress in the weld, normal stress in the beam, buckling load on the beam and tip deflection of the beam. The method is then used to obtain the optimal shape of an engine connecting rod, that minimizes its weight when subject to geometric constraints on the shape variables, and behavioral constraints such as stress and buckling loads. The results obtained by solving the conventional and robust formulations of this problem, and the considerable savings in time that result by virtue of using the fast reanalysis technique are presented. The methodology presented in this work is expected to be useful in reducing the computational effort in obtaining insensitive designs of large structures and machines.
Structural Optimization for Rubberlike Materials Using Analytical Sensitivity Analysis
Authors: Barthold F.-J. , Falk A. , Stein E.
Published: March 2021

We present a differential geometry based formulation of structural optimization which links continuum mechanics and computer aided design closely together to obtain very naturally fundamental sensitivity data for the optimization procedure. The subsequent discretization process end up with an elegant matrix representation of sensitivity analysis.

The derived sensitivity analysis and the overall optimization procedure was applied to solve structural optimization as well as parameter identification problems for nonlinear elastic materials modelling rubber.
An Octree-Based Heuristic Algorithm for 3-D Packing
Authors: Dai Zuo , Cha Jainzhong , Yuan Junliang
Published: March 2021

Based on the Object-Oriented Simulation System for 3-D Packing developed by Dai & Cha (1993a), this paper presents an effective heuristic algorithm using the Octree Data Structure for the three-dimensional packing problems of irregular components.

It also describes in detail the Tri-Ring Method which is designed for the topology identification of the octree’s construction. For those problems where the total volume of packed items is smaller than that of container, the results of the theoretical analysis and numerical experiments show that the heuristic is excellent both in packing quality and calculation cost. For those problems where the total volume of packed items is larger than that of container, a variant of this method is expected to be also quite effective.

The packing of arbitrarily shaped objects is achieved by packing their octrees generated from their EXTENTS or BOUNDING BOXES.
Design Optimization Considering Flexibility for Working Environment Based on Information of Pareto Optimum Solution Curvatures
Authors: Yoshimura Masataka , Nishikawa Takatoshi
Published: March 2021

This paper presents design decision making methods considering flexibility for change in the working environment. In order to make a clear evaluation of the changes in the optimum levels of the product cost and product performance due to changes in the working environment, three objective design optimization problems are constructed having the three objectives of minimization of the product cost, maximization of the product performance and maximization of flexibility for the working environment. The Pareto optimum solution set forming a curvature is obtained for the evaluation. Then, a method for determining the preferable design solution using information from the Pareto optimum solution curvature is presented. Finally, the proposed methods are applied to design examples for demonstrating effectiveness.
On the Optimal Design of Bodies With Material Symmetries
Authors: Landriani Giannantonio Sacchi , Taliercio Alberto
Published: March 2021

These notes are concerned with the optimal design of two dimensional, in-plane loaded structural elements and three dimensional bodies, made of aleotropic materials, with regard to both the elastic and the ultimate behaviour.

Sec. 2 is devoted to finding the local orientations of the material symmetry axes in 3D orthotropic solids, corresponding to extreme values of the global elastic stiffness. These orientations are shown to be such that collinearity of principal stress and principal strains is achieved throughout the body. In the particular case of transversely isotropic or cubic materials, optimal orientations are shown to depend both on a material parameter and the strain field. A certain orientation of the material symmetry axes may correspond either to a minimum or to a maximum in the elastic stiffness, depending on whether the material has ‘high’ or ‘low shear modulus’. These results are then specialized to plane orthotropic bodies, in which case the theoretical findings obtained by other authors are recovered. In the plane case, also simultaneous optimization of fiber orientation and density is dealt with.

Sec. 3 concerns optimal limit design of plastic 2D in-plane loaded orthotropic structures. Fiber orientation and density are assumed as design variables. Here again, necessary optimality conditions are analytically found and their mechanical interpretation is studied. Analogies with both the numerical results of other authors and the elastic case are observed and discussed as well.
Variable-Topology Shape Optimization With a Control on Perimeter
Authors: Haber Robert B. , Jog Chandrashekhar S. , Bendsøe Martin P.
Published: March 2021

This paper describes a new method for variable-topology shape optimization. The method addresses certain problems that arise in relaxed formulations (i.e., homogenization design methods). For example, a complete relaxation generates optimal designs containing material with perforated microstructures that may be difficult or expensive to manufacture. Formulations that penalize perforated material, either explicitly or through a partial relaxation, can generate manufacturable designs. However, the same illposedness that motivates relaxed formulations reappears as the penalty against perforated material is strengthened. The practical consequence is that numerical implementations of the penalized formulations fail to converge with grid refinement.

The new approach uses a control on the design perimeter to effectively exclude chattering designs (which have an infinite perimeter) from the feasible solution space. This achieves a well-posed shape design problem without the introduction of microstructure. Numerical examples demonstrate that manufacturable designs can be obtained in a single, automatic operation. Grid refinement improves geometric resolution without altering the design topology. The new method also provides a means to control the number and the length scale of holes in the optimal design.
A Unified Multidisciplinary Optimum Design Method Using Genetic Algorithms
Authors: Yamakawa Hiroshi
Published: March 2021

Multidisciplinary optimum designs have been of strong interest lately in many fields. A unified multidisciplinary optimum design method by utilizing the genetic algorithms is presented in this study. The design process is modeled there by a distributed hierarchical system to simulate ordinary design processes. Each level is optimized by genetic algorithms somewhat independently but some information is transmitted to the upper or the lower level. Engineering analysis can also be involved in a certain level. The proposed method is then applied to simple examples of preliminary designs of cars and numerical results show the effectiveness of the method.
Decision Decomposition for the Lifecycle of the Design Process
Authors: Fallin T. Wade , Thurston Deborah L.
Published: March 2021

Expanding design analysis to include lifecycle considerations makes design decision making more complex. This paper presents a methodology for structuring the lifecycle of the design decision making process itself in order to efficiently utilize designers’ time. The first step involves organizing performance objectives and decision variables into a hierarchical matrix structure defining the design space. Then, vertex partitioning is performed on a graph representation of the design space to delineate distinct stages where only a subset of decision variables are analyzed. An example of the parametric design of an artificial hip illustrates the methodology.
“Chaos” by Design in Mobile Robots
Authors: Shanmugasundram Arulkumar P. , Desa S.
Published: March 2021

A large class of tasks for mobile robots require the robot to cover an enclosed space that might contain several objects (obstacles). The usual approach to this problem is to design a sensor-intensive, computer-controlled robot that usually has a relatively simple kinematic form (type). The control of such a robot is difficult, expensive, and frequently unreliable. This paper demonstrates how the complexity in sensing and control can be circumvented by synthesizing a “chaotic” kinematic motion that, when appropriately embodied by a kinematic form, covers the space and easily deals with obstacles. The evolution of the “chaotic”, sensorless, mechanical mobile robot from concept, through analysis, numerical simulation and form embodiment, to realization is described. The testing of the prototype clearly demonstrates how, for the present task, complex “chaotic” motions do considerably simplify the control of the robot. A computer controlled prototype capable of mimicking the behavior of its mechanical counterpart is also described.
Numerical Algorithms for Mapping Boundaries of Manipulator Workspaces
Authors: Haug Edward J. , Luh Chi-Mei , Adkins Frederick A. , Wang Jia-Yi
Published: March 2021

Broadly applicable numerical algorithms for mapping boundaries of manipulator accessible output sets are developed and illustrated. Accessible output sets for planar and spatial manipulators are defined and analytical criteria determining their boundaries are stated, for both manipulators having the same number of input and output coordinates and redundantly controlled manipulators with a larger number of inputs than outputs. A method is presented for finding an initial point on the boundary of the accessible output set. From this point, a continuation method is used to map a family of one dimensional solution curves on the boundary. A method for finding tangents to solution curves at bifurcation points of continuation equations is presented and a computational implementation in the form of an experimental computer program is outlined. A planar redundantly controlled serial manipulator, a planar Stewart platform, and a spatial Stewart platform are analyzed, determining both the exterior boundary of the accessible output set and interior curves that represent local impediments to motion or controllability.
Dynamics of a Flexible-Link Planar Parallel Manipulator in Cartesian Space
Authors: Fattah Abbas , Misra Arun K. , Angeles Jorge
Published: March 2021

The subject of this paper is the modeling and simulation of a flexible-link planar parallel manipulator in Cartesian space. Given a desired end-effector motion, the inverse kinematics and inverse dynamics of a rigid-link model of the parallel manipulator is used to obtain actuated joint torques. The actual end-effector motion and vibration of the flexible links are obtained using simulation (direct dynamics) for the flexible-link manipulator. Finite elements are used to model the flexible links, while the Euler-Lagrange formulation is used to derive the equations of motion of the uncoupled links. The equations of motion of all the links are assembled to obtain the governing equations for the entire system. The methodology of the natural orthogonal complement, which has been previously applied to flexible-link systems with open-chain structures, is used here to eliminate the constraint forces. Finally, geometric nonlinearities in elastic deformations, which are very important in high-speed operations, are also considered.
Kinematic Passive Correction of Errors in Active Surfaces
Authors: Smith David R.
Published: March 2021

The advancing requirements of instrumentation in astronomy has led to the development of telescopes with segmented active surfaces. In such telescopes, movable segments are controlled together to maintain the correct figure of the reflecting surface. This paper investigates telescope active surfaces by representing each movable segment as a 3-degree of freedom (DoF) parallel manipulator of the type described by Lee and Shah (1988a, 1988b). The workspace of this manipulator is examined for two types of actuator mounting geometries. In the first case, pin joint connections are placed at the base and ball joints at the end-effector. In the second case, the joints are reversed. Following a general investigation, the results are specialized to reflect the behavior of small motions, as active surfaces require only small adjustments. Finally, the effects of the kinematics on the performance of an example surface are determined. The analysis reveals that placing the ball joint connections at the base provides a passive correction of uncontrolled states in the surface.
Automatic Generation of the Input-Output Equations of Planar Mechanisms
Authors: Kanberoglu Kunter A. , Soylu Resit
Published: March 2021

In this article, a methodology, which yields (in closed-form) the functional relation between “any” two joint variables of a one degree-of-freedom planar mechanism, is developed. For instance, the transmission angle and crank-rotatibility synthesis algorithms (Soylu, 1993; Soylu and Kanberoğlu, 1993) require such a generic input-output equation. The equation is obtained in an optimal manner which minimizes the computational effort associated with it. The tools of theory of elimination and symbolic manipulation are also used in the developed method.
Change-Point Configurations of RSSR and Other Bimodal Linkages
Authors: Ting Kwun-Lon , Dou Xiaohong
Published: March 2021

In this article, an analytical method is developed for finding change-point positions of RSSR and other bimodal linkages. At a change-point position, the input or output discriminant function and its derivative with respect to the input angle are equal to zero. The method is demonstrated in studying the effect of the skew distance between the joint axes to the existence of change-positions and offering the first successful systematic search of general RSSR change-point linkages. Like planar four-bar linkages, the issue of change-point linkages is pivotal to the understanding of the mobility and assemblability of the RSSR linkage and other bimodal linkages.
The Linear Representation of the Screw Triangle: A Unification of Finite and Infinitesimal Kinematics
Authors: Huang Chintien , Chen Chien-Ming
Published: March 2021

This paper presents the linear representation of the screw triangle. The resultant twist of two finite twists is shown to be a linear combination of five screws. The linear representations of all degenerate screw triangles are also derived. The limiting cases of these results of finite displacements confirm the theory of screws in infinitesimal kinematics. The finite kinematic analysis of multi-link serial chains is performed by using the linear representation of the screw triangle to demonstrate a unification of finite and infinitesimal kinematics.
Optimum Design of a Spatial 7R Homokinetic Linkage
Authors: Jiyuan Zhang , Shoufan Shen
Published: March 2021

In this paper, an optimum design method based on orthogonal tables is applied to the design of a spatial 7R homokinetic linkage. An optimum design problem is first formulated; then, an optimum design, with a coefficient of speed fluctuation δ < 2.52%, has been achieved, as reported here.
Numerical Phenomena of a Spatial Mechanism With Clearances
Authors: Jianling Zhang , Zhe Li , Shixian Bai
Published: March 2021

The general mechanical model of C pair with clearances is set up and used to derive the differential equation of motion of a RSCR mechanism with clearance at C pair in this paper. The numerical results are analysed and compared with the dynamic responses of the nominal RSCR mechanism. Chaotic phenomena can be seen in the numerical results, which indicate that the steady state responses may not be achievable for spatial mechanisms with clearance connections.
A Symbolic-Numerical Approach for the Synthesis of Planar Rigid-Body Guidance
Authors: Chen Yong , Fu Jinyuan
Published: March 2021

Based on the pole method and the computer symbolic manipulating technique, a fourth order algebraic equation with single variable has been derived for the closed form solution of planar rigid-body guidance. The newly developed method eliminates the requirement of sloving system of nonlinear equations. All solutions of the problem can be obtained directly and easily without the need of initial values. A numerical example is given demonstrating the efficiency and advantages of the method.
An Efficient Algorithm for Computing the Steady-State Dynamic Response of High-Speed Mechanisms
Authors: Selstad Tyler J. , Farhang Kambiz
Published: March 2021

An efficient method for obtaining the steady-state response of linear systems with periodically time varying coefficients is developed. The steady-state solution is obtained by dividing the fundamental period into a number of intervals and establishing, based on a fourth-order Rung-Kutta formulation, the relation between the response at the start and end of the period. Imposition of periodicity condition upon the response facilitates computation of the initial condition that yields the steady-state values in a single pass; i.e. integration over only one period. Through a practical example, the method is shown to be more accurate and computationally more efficient than other known methods for computing the steady-state response.
Stiffness Model of Coiled Springs Including the Axial Asymmetry due to the Helical Geometry
Authors: Lindkvist Lars
Published: March 2021

The stiffness of a short section of a coiled spring is derived by writing the elastic energy in the spring wire, considering its actual geometric form, and then applying the Castigliano theorem. The resulting linear stiffness model includes the effects of pitch, curvature of the wire and distortion due to normal and transverse forces in the wire. Further, the starting and ending points of the spring wire are taken into consideration.

This stiffness model is used to derive the locally linearized stiffness matrix for a complete coiled spring that is laterally loaded. The stiffness matrix is evaluated by first calculating the non-linear deformation for a given external load and then linearizing the analysis about that equilibrium point. The deformation is calculated by summing the contributions from a number of small spring elements for which the deformations are considered to be linear.

The natural frequencies of a mechanical system consisting of a rigid body and a laterally loaded spring are calculated and compared with experimental results. These experiments clearly verify the proposed theoretical stiffness matrix for the complete spring and detect the rotational asymmetry of the spring.
An Automated System for Cam Design and Manufacture
Authors: Tsai Wu-Jung , Lee Jyh-Jone
Published: March 2021

In this paper, we developed an automated system for the design and manufacture of three-dimensional cams. This system incorporates the computer-aided design, manufacturing and inspection three sequences into one automated process. First, a computer package employing the theory of gearing is developed for synthesizing and animating cam mechanisms. Then, a module for generating NC programs for a five-axis CNC machine to manufacture spatial cams is established. Finally, a computer-aided inspection system for measuring cam profile is introduced. This automated CAD/CAM/CAI system is illustrated with an example on the design of a roller gear cam.
Computerized Design and Generation of Low-Noise Helical Gears With Modified Surface Topology
Authors: Litvin F. L. , Chen N. X. , Lu J. , Handschuh R. F.
Published: March 2021

An approach for design and generation of low-noise helical gears with localized bearing contact is proposed. The approach is applied to double circular arc helical gears and modified involute helical gears. The reduction of noise and vibration is achieved by application of a predesigned parabolic function of transmission errors that is able to absorb a discontinuous linear function of transmission errors caused by misalignment. The localization of the bearing contact is achieved by the mismatch of pinion-gear tooth surfaces. Computerized simulation of meshing and contact of the designed gears demonstrated that the proposed approach will produce a parabolic transmission errors function when misalignment is present. Numerical examples for illustration of the developed approach are given.
Concurrent Multiaxial Damper Design for Damping Augmentation of a 3-Cable Suspension System
Authors: Yang Li-Farn
Published: March 2021

An approach to the concurrent design of the multiaxial inertial dampers for damping augmentation of the Multi-Body Dynamic (MBD) system is presented. The system considered herein features a 3-cable mechanism that acts as a suspension system equipped with the 3-axial inertial dampers atop a stable platform. Such a damping device has been introduced as an application in eliminating the attendant vibrations of the 3-cable suspension system for use in the preflight validation testing of flexible space structures. The primary objective is aimed at optimally designing three independent dampers in a concurrent procedure, in which an optimization is developed to minimize mean-squared motion in an attempt to augment damping of the 3-cable suspension system against the pendulum vibrations. This leads to the simultaneous tuning of three inertial dampers without any loss of cross-coupled damping effect from the MBD standpoint. Comparison of the simulated-time histories for the cases of damped and undamped vibrations is presented to show the effectiveness of the present approach.
Computer-Aided Sketching of Epicyclic-Type Automatic Transmission Gear Trains
Authors: Chatterjee Goutam , Tsai Lung-Wen
Published: March 2021

The enumeration of epicyclic gear mechanisms in the form of graphs gives rise to the need of a methodology for reverse transformation, that is, for constructing the mechanisms from graphs. This paper addresses the issue by discretizing an epicyclic gear mechanism into Fundamental Geared Entities. Further, these geared entities are shown to be a conglomeration of four primitives; namely, the carrier, sun, ring, and the planet gear. An algorithm is formulated to create the entities from a graph by using these primitives. The entities are then connected together to form a mechanism.
An Efficient Method for Evaluating Steady-State Response of Periodically Time-Varying Linear Systems, With Application to an Elastic Slider-Crank Mechanism
Authors: Farhang Kambiz , Midha Ashok
Published: March 2021

This paper presents the development of an efficient and direct method for evaluating the steady-state response of periodically time-varying linear systems. The method is general, and its efficacy is demonstrated in its application to a high-speed elastic mechanism. The dynamics of a mechanism comprised of elastic members may be described by a system of coupled, inhomogeneous, nonlinear, second-order partial differential equations with periodically time-varying coefficients. More often than not, these governing equations may be linearized and, facilitated by separation of time and space variables, reduced to a system of linear ordinary differential equations with variable coefficients. Closed-form, numerical expressions for response are derived by dividing the fundamental time period of solution into subintervals, and establishing an equal number of continuity constraints at the intermediate time nodes, and a single periodicity constraint at the end time nodes of the period. The symbolic solution of these constraint equations yields the closed-form numerical expression for the response. The method is exemplified by its application to problems involving a slider-crank mechanism with an elastic coupler link.
MinnSketch©: A Graphic Kinematic and Dynamic Analysis Tool for Planar Mechanism Design
Authors: Ho Chengta , Erdman A. G. , Riley Donald R.
Published: March 2021

MinnSketch© is a new conceptual design package for the generation of planar mechanisms. This program is implemented in C and runs in an X/Motif graphic environment. MinnSketch allows users to intuitively construct a mechanism from scratch and to rapidly develop the conceptual model to a workable solution. The purpose of developing this program was to create an intuitive design tool, so the user interface was designed to closely model the real-world environment. By directly manipulating the graphic conceptual model intuitively with the aid of the feedback from the simulation and analysis results, users can thoroughly understand their designs and thus can increase their productivity.
The Automatic Sketching of Planar Kinematic Chains
Authors: Zhixing Wang , Wenhui Li , Huamin Li , Ruimin Wu
Published: March 2021

This paper presents a method for the automatic generation of independent loops and peripheral loops of planar kinematic chains. In order to implement this method, three laws are brought out and some new concepts, for instance, same-position-link, similar-loop, loop-link-vector, loop-joint-vector, loop-link matrix and loop-joint matrix, etc., are defined. Finally, planar kinematic chains are sketched automatically according to these loops generated.
Computer Aided Design for High Mechanical Efficiency of Wolfrom Type Speed Reducers
Authors: Orlandea Cosmin , Tataru Ovidiu
Published: March 2021

Wolfrom type planetary speed reducers are complex planetary transmissions, formed of three simple planetary mechanisms that have the same carrier H.

The main characteristic of this kind of reducers is the large transmission reduction ratio (usually by a factor of 100 ... 300), obtained with a relatively small sized reducer.

Generally, high transmission ratio reducers have the capability to output high torque. Considering the fact that their physical size is small, there are high normal loads between the teeth of the component gears and in the bearings, increasing the internal losses of the system.

The object of this paper is to help the designer of this type of speed reducers to find the limits of the transmission ratio corresponding to an acceptable mechanical efficiency and size.

We have expressed all the relations as functions of only three variables (z1, a and δ), that best define the integer type of relations involved in this paper. Based on these relations, we have created a computer program to optimize the value of the total mechanical efficiency of the planetary train.
On the Mobility of Compliant Mechanisms
Authors: Murphy Morgan D. , Midha Ashok , Howell Larry L.
Published: March 2021

The topological synthesis for a compliant mechanism leads to a very large number of design options from which to select a final design. Therefore, an evaluation of a mechanism’s ability to meet selected criteria provides a means of reducing a large number of possible designs to a smaller set of acceptable designs. One criterion deals with a mechanism’s potential mobility. For mechanisms containing flexible members, the response to inputs, in general, is comprised of both rigid-body and elastic deflections of their members. This paper deals primarily with the development of a technique for the determination of mobility characteristics of compliant mechanisms, employing a mathematical model previously developed for compliant mechanisms.
A Linear Scheme for the Displacement Analysis of Micropositioning Stages With Flexure Hinges
Authors: Her I. , Chang J. C.
Published: March 2021

In this paper we present an analytical scheme for the displacement analysis of micropositioning stages with flexure hinges. The proposed scheme is based on linearization of the geometric constraint equations of the stage structure. A design chart for evaluating the stiffness of the flexure hinge is also presented in this paper. This chart provides more accurate estimations than the design formula presently in use. The proposed linear scheme is general, easy to use, yet capable of obtaining results close to those obtained from the finite element analysis.
A Modular, Long-Reach, Truss-Type Manipulator for Waste Storage Tank Remediation
Authors: Salerno Robert J. , Reinholtz Charles F.
Published: March 2021

This paper will introduce a new type of modular manipulator system that is particularly well suited for performing long-reach, high-payload operations such as waste storage tank remediation. These new capabilities are achieved by employing an “all-truss” design in which discrete truss modules are used to construct a reconfigurable manipulator system. Each module of the manipulator is either a static truss “link” or one of several possible Variable Geometry Truss “joints.” This paper presents background information, system requirements, a description of the individual components used to construct the manipulator, and an overview of the kinematic analysis algorithms developed to address the redundant nature of the manipulator.
Identification for Manipulators With Joint Compliances and Link Deflections
Authors: Lin Cheng Y. , Chew Meng-Sang , Everett Louis J. , Juang Jer-Nan
Published: March 2021

An iterative forward transformation algorithm is developed to compute the pose at the end effector of a manipulator when subjected to joint compliances and link deflections. The algorithm is based on the homogeneous transformation matrices and a gravity term associated with each joint. In addition, an identification algorithm has been developed to determine the kinematic and structural parameters of a flexible manipulator used in the forward transformation algorithm. As most of the links of a manipulator are not simple beams, the identification algorithm is particular useful to obtain a set of correct parameters. Results of the simulation tests for a 6-DOF robot are shown to check these algorithms.
3-D Object Recognition Techniques: A Survey
Authors: Telagi Mruthyunjaya S. , Soni Athamaram H.
Published: March 2021

Visual systems for inspection and material handling are becoming popular in manufacturing. In last decade visual systems have made commendable progress, but most of the success in their application has been achieved in controlled working environment. Research work is going now in designing intelligent visual systems which can respond to changing working environment. Following is the discussion of different visual systems. Where ever possible we have discussed their merits and limitations. Even though research in this area looks promising still lot of work has to be done to build real intelligent system to satisfactorily apply in the real world.
Automation of a Hydraulic Hose Assembly Plant
Authors: Tennyson Stephen A. , Mehta Sudhir I. , Lentner Bruce J.
Published: March 2021

At present the manufacturing process throughout the hydraulic-hose assembly industry consists of manual operations. A study was conducted to determine the technical feasibility and costs of automating such a manufacturing plant.

This paper describes the two automation concepts that were developed. One employs a robot to transfer hoses between workstations, and the other employs a rotary indexing table. Both concepts employ common linear-positioning fixtures controlled by a programmable logic controller to provide necessary hose manipulations at each workstation. A design for a hose-gripper assembly to contain each hose throughout the manufacturing process was developed, as well as schemes for changing the design of current production machinery to meet automation requirements. Production rate and cost estimates of each automation concept are presented.
A Machine Vision System for Inspecting Hydraulic Hose Assemblies
Authors: Mehta Sudhir I. , Chenoweth Bruce B.
Published: March 2021

This paper describes a machine vision system for inspecting hydraulic hose assemblies. At present the inspection in this industry is done manually and is prone to human error. A specially designed hose gripping mechanism, a mandrel system, and a camera and lighting fixture allows the system to be integrated on a shop floor and is able to inspect various parameters of a fitting. The system allows the inspection to be done more accurately and improves the quality control process.
A Graph Based Heuristic Approach to Automated Assembly Planning
Authors: Yan Xue , Gu P.
Published: March 2021

Automatic generation of product assembly sequence is essential for robotic assembly task planning. In this paper, a graph-based heuristic approach is presented for assembly sequence planning. A product is represented in feature-based product model. A liaison graph is then formed based on assembly relations among components. The liaison graph is split into two or more pieces by removing the cutvertex from the graph. The pieces may also be split again until basic graph(bi-connected graph) are found. The basic graphs are considered as sub-assemblies. The disassembly sequence for each sub-assembly is determined. The disassembly sequences are then merged to generate a complete disassembly sequence for the product. Finally, the assembly sequence is defined by reversing the complete disassembly sequence.
Towards a Formal Model of Version and Configuration Management for Collaborative Engineering
Authors: Krishnamurthy Karthik , Law Kincho H.
Published: March 2021

This paper presents a formal model for the management of data for collaborative design that supports the requirements in each design discipline and provides a framework to integrate the individual designs to describe the overall project. A version model is proposed to manage design data in a given discipline, where a version specifies the state of a particular design in that discipline. The versioning scheme is hierarchical in structure and supports the independent evolution of multiple alternatives. In addition, this model proposes configurations as a mechanism to integrate designs from individual discipline. A configuration is defined as a set of component versions (one from each participating discipline) and an associated set of constraints. Finally, this paper discusses a model of versions to support configurations, and enumerates the preconditions on the operators related to version and configuration management.
Mechanical System Information Management in a Shared Multidisciplinary Environment
Authors: Wu J. K. , Yang X. , Li X. , Kvidera D. A.
Published: March 2021

This paper describes the information model and data management methods developed for the global database of a Concurrent Engineering environment for mechanical system design and evaluation. The environment considered has a CAD system and four CAE applications. The information model supports these engineering disciplines through multiple, unrestricted product composition hierarchies and a shared product definition. The dependency between the shared product definition and application models and between attributes of the parameterized, shared product definition are analyzed. The data management method employs a versioning policy that maintains consistent representations and history of the design as it undergoes design change transactions.
Tools and Methods for Performance Evaluation of RDBMS Applications
Authors: Rumpler Béatrice , Polo Mario , Razafimandimby Benjamin
Published: March 2021

The goal of our research is to predict performance of applications using ORACLE RDBMS and then to propose tools to optimize performance.

The performance we are interesting in, is the performance as perceived by users. We then specially study user’s transactions response time.

Our method is based on measurement, and the first step was to measure performance on existing applications using ORACLE RDBMS. We have developed several software tools:

- user simulator

- application generator

- workload application generator

- measurement tools to measure user transactions response time and system activity during a transaction execution.

The second step consisted in data collection and data analysis of measures. The data analysis, based on statistic methods, has permitted to extract the most influent factors and to understand how they can enhance applications performance (Rumpler and Polo, 1993).

We are now able to present the most part of these results.

The last step will consist in building the rules of an expert system for configuration and tuning assistance of ORACLE RDBMS applications. We also analyse the impact of operating system (UNIX) parameters on performance, and these information will complete our expert system possibilities.

The present paper will describe precisely this research with tools developed, methods used, and results.