bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Aircraft Engine Flight Mission Severity Caused by Erosion
Authors: Brandes Tim , Koch Christian , Staudacher Stephan
Published: April 2021

More and more attention is being devoted to assessing severity of the engine operation for a high number of flights in a minimum of time. Compressor erosion is one of the physical phenomena contributing to this severity. Hence, an effective method is developed which allows a general judgment of the severity of engine operation with regard to compressor erosion. The shortening of the camber line at blade leading edge is selected as the parameter describing the degree of severity. The particle impingement conditions experienced by compressor blades throughout a flight mission are computed using a flight mission simulation and a non-dimensional engine model. Local flow conditions of all compressor blade rows are derived from mean line computations. A dimensional analysis of a straight through swirling annulus flow led to a simplified model of particle separation within the compressor blade rows. It turns out that bypass ratio, bleed setting, and degree of particle separation changing from operating point to operating point are significant drivers of erosion. Fan root and booster suffer less from compressor erosion than the high pressure compressor. The flight segments taxi, take-off, take-off climb, climb, and cruise are significantly impacting the severity of a flight mission with regard to compressor erosion.
Film Cooling Superposition Theory for Multiple Rows of Cooling Holes With Multiple Coolant Temperatures
Authors: Fuqua Matthew N. , Rutledge James L.
Published: April 2021

The classical method of superposition has been used for several decades to provide an estimate of the adiabatic effectiveness for multiple sets of already well-characterized film cooling hole rows. In this way, design work is aided by classical superposition theory prior to higher fidelity experiments or simulations that would account for fluid dynamic interaction for which superposition cannot account. In the present work, we consider the additive effects of multiple rows of coolant holes, but now also with coolant issuing at different temperatures. There are a number of ways that coolant may issue from different cooling hole rows at different temperatures, one of which is simply the necessarily different internal channels through which the coolant must pass. The film cooling effectiveness is investigated for double rows of cooling holes wherein the two rows have different coolant temperatures. A double row consisting of an upstream slot and a downstream row of 7–7–7 cooling holes were first evaluated with a single coolant temperature to demonstrate that classical superposition theory applies well to the present configuration. Superposition theory is then extended to the context of multiple coolant temperatures and a new nondimensional parameter is identified, which governs cooling performance. The theory is experimentally evaluated by independently varying the coolant temperatures of the two rows. Circumstances are identified in which the second row of cooling holes may be detrimental to cooling performance.
Data-Driven Analysis of Locomotion for a Class of Articulated Mobile Robots
Authors: Carbonari Luca , Botta Andrea , Cavallone Paride , Tagliavini Luigi , Quaglia Giuseppe
Published: April 2021

In the recent past, the use of autonomous vehicles is becoming of relevant interest in several fields of application. In many cases, the use of articulated structures is preferred to single chassis robots for their peculiar modularity. Such vehicles are often built as an active front module and a rear one that is pulled passively or that can contribute to the vehicle traction when required. Understanding whether this contribution is convenient or not is the main matter of this paper. Two different mobile robots of different scales and purposes are taken into consideration. A dynamic model is presented and analyzed. An experimental validation of the model parameters is also presented in order to make it exploitable as a reliable analysis tool. At last, a simple yet effective actuation law is tested for both the considered robots to evaluate whether the contribution of the back module is beneficial or not to the whole machine maneuverability.
Experimentally Identified Models of McKibben Soft Actuators as Primary Movers and Passive Structures
Authors: Olson Gina , Manjarrez Holly , Adams Julie A. , Mengüç Yiğit
Published: April 2021

Soft robots join body and actuation, forming their structure from the same elements that induce motion. Soft actuators are commonly modeled or characterized as primary movers, but their second role as support structure introduces strain–pressure combinations outside of normal actuation. This article examines a more complete set of possible strain–pressure combinations for McKibben actuators, including passive or unpressurized, deformation, pressurized extension and compression of a pressurized actuator beyond the maximum actuation strain. Each region is investigated experimentally, and empirical force–displacement–pressure relationships are identified. Particular focus is placed on ensuring that empirical relationships are consistent at boundaries between an actuator’s strain–pressure regions. The presented methodology is applied to seven McKibben actuator designs, which span variations in wall thickness, enclosure material, and actuator diameter. Empirical results demonstrate a trade-off between maximum contraction strain and force required to passively extend. The results also show that stiffer elastomers require an extreme increase in pressure to contract without a compensatory increase in maximum achieved force. Empirical force–displacement–pressure models were developed for each variant across all the studied strain–pressure regions, enabling future design variation studies for soft robots that use actuators as structures.
A Systematic Optimization Design Method for Thermal Management of Passenger Vehicles
Authors: Zhang Jie , Wang Qi-Dong , Zhang Han , Zhang Min , Lin Jian-Wei
Published: April 2021

In this study, a systematic optimization method for the thermal management problem of a passenger vehicle was proposed. This article addressed the problem of the drive shaft sheath surface temperature exceeded allowable value. Initially, the causes and initial measures of the thermal problem were studied through computational fluid dynamics (CFD) simulation. The key measures and their parameters were determined through the Taguchi method and significance analysis. A prediction model between the parameters and optimization objective was built by the radial basis function neural network (RBFNN). The prediction model and particle swarm optimization (PSO) algorithm were combined to calculate the optimal solution, and the optimal solution was selected for simulation and experimental verification. Experiment results indicated that this method reduced the drive shaft sheath surface temperature promptly, and the decreasing amplitude was 22%, which was met the experimental requirements.
Thermo-Economic Assessment and Multi-Objective Optimization of an Innovatively Designed District Cooling System in Saudi Arabia
Authors: Alsagri Ali Sulaiman
Published: April 2021

The experience of leading countries in distributed energy systems (e.g., Scandinavian countries) shows that district cooling systems are highly beneficial techno-economic-environmentally by facilitating the use of waste heat resources, solar energy, etc. for cold supply at large scales. This study proposes the optimal development of a novel district cooling design equipped with a large-scale cold storage unit and utilizing the exhaust waste heat of an energy plant in a case study in Saudi Arabia. The optimal configuration of the hybrid system, the sizing of its components, and operating conditions are found using multi-objective optimization techniques based on the genetic algorithm method and a creative performance assessment index. Then, the feasibility of this optimized proposal is investigated through comprehensive thermodynamic and economic analyses. The results show that a district cooling system can surely cope with the harsh climate condition of the case study and provide the required interior comfort conditions. The energy and exergy efficiencies of the system can be as high as 62% and 53% using an absorption chiller utilizing a power plant’s waste heat along with a storage tank for peak shaving. The levelized cost of cooling of the system can be 28 USD/MW h, by which the payback period will be only 8 years.
Compatibility Representation of Knowledge About Design for Net Shape Manufacturing
Authors: Ishii K. , Nekkanti R.
Published: April 2021

This paper proposes a model for representing knowledge about design for net shape manufacturing (NSM) and a means of applying the model to conduct simultaneous engineering. The three major issues that the designers have to balance are: 1) user requirements, 2) process constraints, and 3) candidate designs. We view the goal of design for NSM to be achieving the best possible compatibility among these three issues. Expert designers develop skilled know-how of achieving good compatibility. This paper conceptualizes this knowledge as compatibility-data (c-data) and constructs a knowledge-base CKB. Further, we present two methods that use the CKB to help designers. The first method is the compatibility-based classification system (CCS) which, given the user requirements and the process constraints, searches the CKB for candidate designs. The second is the design assessment system which utilizes the concept of design compatibility analysis (DCA). Given a partial or full description of all the three issues, DCA evaluates the overall compatibility and gives suggestions for improvement, i.e., to modify the design, to respecify the process, or to negotiate the user requirements. Both methods accommodate hardness of constraints, the degree to which the constraints must be satisfied. Using these systems, designers can rapidly generate sound part designs that satisfy requirements and are producible. We illustrate our model by an example: injection molded composite shells for electrical connectors.
Rules of Constructing Primitives for Integration of Design and Manufacture
Authors: Weiying Duan , Ji Zhou , Jun Yu
Published: April 2021

This paper analyzes the difficulties of basic primitives of geometric modeling systems currently in effect, which is met in the application of numerical control manufacture. On the bases of the analysis, the paper proposes the primitive designing rules for the integrated CAD / CAM systems. The paper is divided into four parts. The first part analyzes the defects of often-used primitives. The second part discusses requirements of primitive in the integration of design and manufacture, and proposes the basic rules and unified method of designing primitives. The third part introduces rules and basic principles of constructing primitives offered by the writer. The last part provides an example to show the advantages of the modeling rules.
A Transformational Approach to Mechanical Design Using a Bond Graph Grammar
Authors: Finger S. , Rinderle J. R.
Published: April 2021

During the design process, a designer transforms an abstract functional description for a device into a physical description that satisfies the functional requirements. In this sense, design is a transformation from the functional domain to the physical domain; however, this transformation process is not well characterized nor understood for mechanical systems. The difficulty arises, at least in part, because mechanical designs are often composed of highly-integrated, tightly-coupled components where the interactions among the components are essential to the behavior and economic execution of the design. This assertion runs counter to design methodologies in other engineering fields, such as software design and circuit design, that result in designs in which each component fulfills a single function with minimal interaction. Because of the geometry, weight, and cost of mechanical components, converting a single behavioral requirement into a single component is often both impractical and infeasible. Each component may contribute to several required behaviors, and a single required system behavior may involve many components. In fact, most mechanical components perform not only the desired behavior, but also many additional, unintended behaviors. In good mechanical designs, these additional behaviors often are exploited.

The long term goal of our research is to create a transformational strategy in which the design specifications for a mechanical system can be transformed into a description of a collection of mechanical components. To realize this goal requires formal representations for the behavioral and the physical specifications of mechanical systems as well as formal representations for the behaviors and the physical characteristics of mechanical components. Because the interactions of components are important in our synthesis strategy, the representation of the behaviors of mechanical components must be linked to the representation of their physical characteristics; that is, we are concerned with modeling the relationship between form and function of components. Finally, we need a strategy that enables us to transform an abstract description of the desired behavior of a device into a description that corresponds to a collection of available physical components.

In this paper, we present a graph-based language to describe both the behavioral specifications of a design as well as the behavior of the available physical components. We also briefly discuss a graph-based grammar for the representation of the physical characteristics of the components that enables us to guide the translation from specifications to components [Pinilla 89]. The transformation strategy is discussed in a companion paper [Hoover 89].
Estimating Jacobian and Constraint Matrices in Variational Geometry Systems
Authors: Martino P. M. , Gabriele G. A.
Published: April 2021

The use of variational geometry (or parametric programming as it is sometimes referred as) is becoming a growing trend in current computer aided design systems. Currently, its most important application has been in the quick redimensioning of CAD models and the tying of the geometric relationships in the model to engineering relationships used in design. Another important application that has not reached its full potential is in the area of tolerance design. A key operation in variational geometry systems is the estimation of a jacobian matrix, or a closely related linear program constraint matrix. This paper explains what variational geometry is, how it can be used in redimensioning and tolerance design, and the role of Jacobian and constraint matrices in variational geometry. In this paper we address methods for quickly, and accurately, estimating the required Jacobian and constraint matrices in variational geometry systems.
A Part Feature Description Model for Process Planning of Rotational Parts
Authors: Rho H.-M. , Sheen D.
Published: April 2021

This study documents the development of the Automated Process And Sequence Selector (APASS) model and associated computer software. APASS can be effectively used to automate the selection of machine tools for rotational parts during the process planning procedure for these parts. The APASS model bases its machine tool decisions on part feature description, such as surface shape, technical information! and part header information. Data on the surface shape are transformed automatically based on conversion tables to output suggested machining processes and machine tools. These processes are further filtered by technical information contained within the master and machine files. The ultimate APASS output is a sequence of machining operations based on both the geometrical and dimensional tolerances of the part surfaces and the machine availability. The program has been written in MS PASCAL and currently run on IBM PC/AT compatible.
A Method to Find Parametric Bicubic Surface Intersections
Authors: Chiang L. E. , Wilde D. J.
Published: April 2021

This paper discusses the problem of finding the intersection between two bicubic parametric patches. This is an important problem in Geometric Modeling since bicubic parametric patches are the most common design element in this field. A brief discussion of the existing approaches such as surface subdivision and curve tracing is given first. Next the algebraic solution to solve the intersection between cubic parametric curves is described in order to lay the foundations for an original algebraic method to solve the analog surface case.
A Knowledge Based Geometric Modeling System for Preliminary Design Using Object-Oriented Approach
Authors: Akagi S. , Fujita K.
Published: April 2021

A knowledge-based geometric modeling system for preliminary design was developed using object-oriented approach. Three types of knowledge for design, i.e. the model representing a design product including the geometric model, the procedures manipulating the design product and the knowledge managing the design process were integrated in the system. The model built up with object-oriented programming provides an effective and flexible design environment. Finally, the system was applied to the preliminary design of a ship’s hull arrangement to ascertain its validity and effectiveness.
A New Geometric Model: Distance Measure Model
Authors: Nonaka U. , Tokumasu S. , Kawashima Y. , Takahashi K.
Published: April 2021

A new geometric model, a Distance Measure Model is presented, wherein the internal description of a shape is defined as a procedure whose function is to derive a set of data which describes the relative positional relation between the shape and a given reference point. Then, the modeller is constructed according to an object oriented scheme. A prototype of the modeller demonstrated its wide capabilities as the next generation’s geometric model.
Five-Axis Swept Volumes for Graphic NC Simulation and Verification
Authors: Sambandan K. , Wang K. K.
Published: April 2021

This paper explains in detail a simulator that has been developed for graphic verification of five-axis Numerical Control (NC) machining. Exact parametric representations for the surfaces generated by common NC milling cutters during five-axis motions have been derived using the theory of envelopes as the mathematical basis. Parts of these surfaces form the boundary of the total swept volume generated. For each cutting motion, the swept volume of the cutter is determined and then subtracted from the stock. The Boolean subtraction is done in the image space at the pixel level, using a modified depth-buffer algorithm. A shaded image of the “as machined” part at the end of each cutting motion is then displayed for verification.
Position Tolerance Verification Using Simulated Gaging
Authors: Etesami F.
Published: April 2021

One of the routine manual tasks in dimensional inspection is the assembly verification of circular features by mechanical gaging. With the aid of coordinate measuring machines or vision systems, this task can be performed more efficiently through simulation or soft-gaging. A formulation is presented for interpretation of 2D position tolerance specifications. Simulated gages are constructed from datum features as a set of constraint relationships. The measure of perfect-form position-imperfection is determined as the distance between the measured and the nominal feature positions subject to datum constraint requirements. The derived formulation is applied to an example part with a hole-slot datum-priority-frame. This formulation results in a three-variable optimization problem which is solved by an Augmented Lagrange Multipliers technique. The extension of the formulation to 3D is also discussed, but without reference to a specific representation.
Concurrent Engineering With Suggestion-Making CAD Systems: Results of Initial User Tests
Authors: Jakiela M. J. , Papalambros P. Y.
Published: April 2021

CAD systems that make suggestions to designers are investigated as an aid to preliminary design and computational tool for concurrent engineering. A system-user test was performed with such a system configured to provide suggestions in three ways: during preliminary design, after preliminary design, and not at all. Five users were tested with each mode. All were given the same design assignment, and all were allowed to refer to the standard book-form concurrent engineering information. The two user groups that received suggestions produced more good designs than did the unaided group. There was little distinction in quality, however, between the two aided groups. Additionally, users that received suggestions stopped using the book-form information very early in the design process and relied solely on the system’s assistance. These results demonstrate that suggestion-making systems can integrate concurrent engineering information into the preliminary design process.
Parametric Computer Aided Hydraulic Cylinder Design: Piston Component Modeling
Authors: Johannesson H. L.
Published: April 2021

In this work a procedure for parametric computer aided design of hydraulic cylinder pistons has been developed. Such a piston is a kind of component that has a geometry that is dependent and determined of surrounding and interacting parts. The piston seal has a very strong influence on the piston geometry, and the kind of piston design rules that can be found in piston seal catalogues have been used in the developed computer programs.

The design procedure is divided in two parts. In the piston family design part, a piston family product model, which is common for a group of pistons with different dimensions but uses the same seal cross section, is created and stored in a piston family product model data base. In the member design part the piston family data is retrieved, dimension determining parameters are given, and one particular piston of a certain size is created and presented.

The software system needed in order to be able to apply the suggested procedure consists of

- a CAD-system, containing a graphic application program language

- a specific CAD-system dependent interface program written in the graphic application program language

- two CAD-system independent interface programs written in a common high level language lite FORTRAN

- CAD-system independent product model data bases

All these programs except the CAD-system have been developed in this work, and the use of the programs is demonstrated with an example.
Structural Synthesis of Sheet Metal Parts: An Analogy to Path Planning Using Manufacturability As a Guide
Authors: Graham P. V. , Ulrich K. T.
Published: April 2021

The structural synthesis of sheet metal parts can be viewed as a path planning problem. A design is represented by a path that links the start points and goal points while avoiding all obstacles.

Techniques used in robot motion planning have proven capable of generating paths through obstacle filled space. Given a problem description, these techniques make it possible to create a variety of initial design candidates, each of which represents a family of topologically distinct designs. These topologically distinct designs partition the solution space. For each family, gradient search techniques based on manufacturability and functionality can be used to obtain a good design within that family. A good overall design is obtained by comparing the designs selected from each family.

Although this work is still preliminary, we have written a prototype program for solving two-dimensional problems, and have used it to explore the properties of the design space.
Manufacturability Analysis for a Flexible Manufacturing Cell
Authors: Anjanappa M. , Courtright M. J. , Anand D. K. , Kirk J. A.
Published: April 2021

The conventional design to manufacture cycle time in producing a part can be reduced by eliminating design errors and difficult to machine features before process planning begins. This paper discusses the identification, development and operation of an approach which uses a data base of flexible manufacturing cell capabilities in order to analyze a design for manufacturability. Designs which the cell protocol is unable to produce are rejected, and ways in which a design may be made more producible are suggested to the user. This paper addresses issues, such as material availability, tool availability and the acheivability of tolerance, as they relate to the flexible manufacturing cell which contains a Matsuura 510V CNC machining center, a robot and simulated AGV and fixturing. An important contribution of this work, which is an integral part of the overall system protocol, is the wide variety of manufacturability constraints covered and the convenience of including it in the overall part design and process planning protocol.
Analysys of Piezoelectric Microactuators Using Finite Element Methods
Authors: Barnett A. R. , Naganathan N. G.
Published: April 2021

Unlike conventional electromechanical actuators, piezoelectric actuators could be utilized to execute precise motions while exerting significantly high forces. In an attempt to pursue the design of a practical three-dimensional piezoelectric micro-actuator, it has become necessary to obtain a full understanding of how such materials behave under arbitrarily applied external voltages. The solution of the governing equations of piezoelectricity by the use of analytical methodologies for even moderately complex scenarios is effectively impossible, A numerical solution scheme based on the method of finite elements has been developed to analyze the deformations of and potentials within piezoelectric materials subjected to external static voltage loadings, A set of dedicated computer codes has been created to model piezoelectric three-dimensional geometries. The specimens chosen for the purpose of numerical studies are representative of real-world piezoceramic materials. The results are found to be in excellent agreement with published product data.
Some Results in Optimization of Non-Hierarchic Systems
Authors: Pan J. , Diaz A. R.
Published: April 2021

A strategy for the optimization of non-hierarchic systems by decomposition into smaller subproblems is presented. Each subproblem is defined by its own set of design variables and functions. The procedure solves each subproblem in sequence and includes a strategy to move away from points that are optimal for all the subproblems but not optimal for the global problem. The same objective function and constraints are present at all levels and the evaluation of non-local functions is made using convex approximations. Examples are provided for illustration.
Global Optimization Using the Multistart Method
Authors: Jain P. , Agogino A. M.
Published: April 2021

Multistart is a novel stochastic global optimization method for finding the global optimum of highly nonlinear mechanical problems. In this paper we introduce and develop a variant of the multistart method in which a fraction of the sample points in the feasible region with smallest function value are clustered using the Vector Quantization technique. The theories of lattices and sphere packing are used to define optimal lattices. These lattices are optimal with respect to quantization error and are used as code points for vector quantization. The implementation of these ideas has resulted in the VQ-multistart algorithm for finding the global optimum with substantial reductions in both the incore memory requirements and the computation time. We solve several mathematical test problems and a mechanical optimal design problem using the VQ-multistart algorithm.
A Hybrid Expert System–Nonlinear Programming Approach to Optimal Gear Design
Authors: Lin K.-C. , Johnson G. E.
Published: April 2021

An expert system is developed for optimal spur gear design. Design automation is accomplished by dividing the design variables into different categories, i.e. geometric design variables and non-geometric design variables. The geometric variables are further divided into terms that are related to the gear mathematical model and terms that are determined according to the designer’s experience. By properly developing the mathematical model, numerical optimisation can be used to seek the best solution for a given set of geometric constraints. The process of determining the non-geometric design variables is automated by using symbolic computation.

This gear design expert system is built according to the AGMA standards and a survey of gear design experts. The recommendations of gear designers and the information provided by AGMA standards are integrated into knowledge bases and data bases. By providing fast information retrieval and design guidelines, this expert system greatly streamlines the spur gear design process and makes it possible for a novice designer to achieve a reliable design in a short period of time.
A General Method for Optimum Design of Gear Boxes Through Nonlinear Programming
Authors: Cleghorn W. L. , Fenton R. G. , Fu J.-F.
Published: April 2021

A general method for the optimum design of gear boxes is presented using a nonlinear programming technique. The mathematical model of the gear box is developed using a symbolic mathematical manipulator. Constraints of the feasible design have been included but reduced to be as few as possible. Identical optimum results were obtained through employing two different optimization methods, the flexible tolerance method and the random search method, for solving an example problem.
Integrated Optimal Design of Planar Mechanisms Using Fuzzy Theories
Authors: Dhingra A. K. , Rao S. S.
Published: April 2021

A new integrated approach to the design of high speed planar mechanisms is presented. The resulting nonlinear programming formulation combines both the kinematic and dynamic synthesis aspects of mechanism design. The multiobjective optimization techniques presented in this work facilitate the design of a linkage to meet several kinematic and dynamic design criteria. The method can be used for motion, path, and function generation problems. The nonlinear programming formulation also permits the imposition of constraints to eliminate solutions which possess undesirable kinematic and motion characteristics. To model the vague and imprecise information in the problem formulation, the tools of fuzzy set theory have been used. A method of solving the resulting fuzzy multiobjective problem using mathematical programming techniques is presented. The outlined procedure is expected to be useful in situations where doubt arises about the exactness of permissible values, degree of credibility, and correctness of statements and judgements.
A Network Optimization Approach to Three-Dimensional Collision-Free Robot Path Planning
Authors: Jain P. K. , Manoochehri S. P.
Published: April 2021

This paper presents a network optimization approach to the generation of tool tip paths in three-dimensional space for robot manipulators working in the presence of obstacles. The developed algorithm relies on a graph structure enumeration of possible path segments between discrete points inside the workspace. An intelligent heuristic scheme is used to select a small searchspace over which the search for the optimal path is carried out. Paths which are optimal with respect to pre-determined objective functions based on robot kinematic and dynamic solutions are synthesized by applying Dijkstra’s minimum cost algorithm. Collision avoidance is checked for the tool tip as well as for the robot body. The methodology is robot independent and can be applied to any robot whose kinematics and dynamics can be solved. A computer program has been developed to implement this approach for three-axis manipulators. Results of the application of this scheme to some robots in this class are also presented.
Shape Optimization of Robotic Manipulators for Maximum Stiffness and Load Carrying Capacity
Authors: Lamancusa S. , Saravanos D. A. , Sommer H. J.
Published: April 2021

Structural optimization can result in robotic arms with significantly improved stiffness and load carrying capacity. The geometrical shape of the manipulator links can be optimized for maximum stiffness-to-weight and strength-to-weight ratios. The problem of stiffening and strengthening a manipulator is solved by optimal redistribution of the available material without increasing the total mass of the manipulator. Since manipulators are programmed to move through a range of postures, thereby creating different loading conditions on the links, a multi-posture design criteria is implemented to provide a more uniform stiffness and strength over the range of possible postures. Finite element based performance criteria are developed which facilitate the simultaneous maximization of specific stiffness and strength. Three application examples on a SCARA class arm illustrate the dramatic potential for simultaneous improvements in specific stiffness and specific strength. The significance of multiple postures on the optimal design, the merits of tapered versus straight link shapes, and the relation of maximum stiffness to maximum strength, are also examined.
Sizing Design Sensitivity Analysis of Dynamic Frequency Response of Vibrating Structures
Authors: Choi K. K. , Lee J. H.
Published: April 2021

Dynamic frequency response of mechanical and structural systems is of interest in design problems that are subjected to harmonically varying external loads caused by the reciprocating power train or other rotating machineries such as motors, fans, compressors, and forging hammers [1]. For example, airplane body and wing structures are subjected to a harmonic load transmitted from the propulsion system. Also, ship vibrations resulting from the propeller and engine excitation can cause noise problem, cracks, fatigue failure of tailshaft, and discomfort to crew. When a machine or any structure oscillates in some form of periodic or random motion, the motion generates alternating pressure waves that propagate from the moving surface at the velocity of sound. For instance, the interior sound pressure in an automobile compartment can occur when the input forces transmitted from road and power train excite the vehicle compartment boundary panels. These motions with frequencies between 20 Hz and 20 KHz stimulate the hearing mechanism of human [2].
Object Oriented Dexterity Analysis and Design Application for Spatial Robot Hands
Authors: Lu L. , Cai C. , Soni A. H.
Published: April 2021

For an arbitrarily shaped object manipulated by a robot hand, this paper presents a procedure for analyzing the position and rotation ranges of the object, and a procedure for designing the kinematic parameters of a hand to meet given requirements on the motion ranges. Rotation dexterity index, dexterity charts, and a dexterity scalar characterizing both position range and rotation range are introduced for the performance evaluation of a robot hand. Least-square-error iteration and steps are detailed for the kinematic parameter determination of a robot hand.
Computer-Oriented Dynamic Analysis Techniques in Vehicle System
Authors: Shin S. H. , Kim J. Y. , Yoo W. S.
Published: April 2021

Several dynamic analysis techniques are compared with a planar vehicle model. Cartesian formulation, the superelement technique, velocity transformation, and the recursive formula are compared. A recursive formula with multiple trees is derived and its simulation algorithm is also developed. The relation between the derived recursive formula and velocity transformation is investigated. When those techniques are applied to a planar vehicle with two independent suspensions, the efficiency of those methods can be evaluated. The efficiency of the derived recursive formula was higher than those of other methods.
A Low-Cost Real-Time Man-in-the-Loop Simulation for Multibody Systems
Authors: Chang J. L. , Kim S. S.
Published: April 2021

This paper presents a general approach for achieving real-time man-in-the-loop simulation for multibody dynamic systems. Emerging real-time dynamics simulation technologies are exploited to develop a low-cost network based simulator as an interactive design workstation with a human operator in the control loop. An efficient recursive dynamic formulation is used to create multibody dynamics models. A parallel processing algorithm is developed based on the recursive dynamics formulation and implemented on a multiprocessor computer to achieve real-time simulation. As a real-time integration algorithm, third-order Adams-Bashforth method is used. The integration stepsize is estimated from the eigenvalue analysis of the equations of motion. High speed computer graphics techniques provide realistic visual display for the simulator. A backhoe simulation is implemented as an example to demonstrate the feasibility of man-in-the-loop simulation on the low-cost simulator.
Dynamic Simulation of a Space Robot Hand-Off Procedure
Authors: Kim S. S. , Lin T.-C. , Haug E. J. , Frisch H. P.
Published: April 2021

Hand-off of an object from the flexible Remote Manipulator System (RMS) to the Flight Telerobot Servicer (FTS) in a space construction application is simulated. The application includes consideration of flexible multibody dynamics, control, and variable system topology. Position synchronization between the FTS end effector and a payload that is attached to the RMS is achieved by controlling the trajectory of the FTS end effector. Special position constraints and orientation rheonomic constraints are developed and imposed to simulate the object capture. Vibration suppression of the flexible arm is studied, using bang-bang controllers in the FTS.
Applications of Symbolic Computing for Numerical Analysis of Mechanical Systems
Authors: Ashrafiuon H. , Mani N. K.
Published: April 2021

The symbolic computing system MACSYMA is used to automatically generate the explicit equations necessary to represent the kinematic constraints and system dynamics and to compute the design sensitivities for optimal design of any multibody system. The logic to construct system matrices and vectors involved in the analysis and design equations is implemented as general purpose MACSYMA programs. All necessary manipulations are performed by MACSYMA and the equations are output as FORTRAN statements that can be compiled and executed. This approach results in a computational saving of up to 95% compared to using a general purpose programs. The approach is general in nature and is applicable to any multibody system. Examples are presented to demonstrate the effectiveness of the approach.
Tailoring of Composite Links for Optimal Damped Elasto-Dynamic Performance
Authors: Saravanos D. A. , Chamis C. C.
Published: April 2021

A method is developed for the optimal design of composite links based on dynamic performance criteria directly related to structural modal damping and dynamic stiffness. An integrated mechanics theory correlates structural composite damping to the parameters of basic composite material systems, laminate parameters, link shape, and modal deformations. The inclusion of modal properties allows the selective minimization of vibrations associated with specific modes. Ply angles and fiber volumes are tailored to obtain optimal combinations of damping and stiffness. Applications to simple composite links indicate wide margins for trade-offs and illustrate the importance of various design variables to the optimal design.
Design of Pitch Cones for Face-Hobbed Hypoid Gears
Authors: Litvin F. L. , Chaing W.-S. , Lundy M. , Tsung W.-J.
Published: April 2021

The authors proposed a method that allows the relations between the pitch cone angles and spiral angles to be determined directly. These relations are represented by a system of three nonlinear equations that are derived from: (i) conditions of tangency of the pitch cones and (ii) the specific location of the head—cutter that generates hypoid gears with face—hobbed teeth of uniform depth. A computer program for the determination of pitch cone parameters has been developed.

Equations have also been derived that allow to determine the location of apices of pitch cones with respect to the line of shortest distance, the coordinates of point of tangency of the pitch cones and the orientation of the plane that is tangent to the pitch cones. The proposed method is illustrated with a numerical example.
A Global Approach for Using Kinematic Redundancy to Minimize Base Reactions of Manipulators
Authors: Chung C. L. , Desa S.
Published: April 2021

An important consideration in the use of manipulators in Microgravity environments is the minimization of the base reactions, i.e. the magnitude of the force and the moment exerted by the manipulator on its base as it performs its tasks. One approach which has been proposed and implemented is to use the redundant degrees of freedom in a kinematically redundant manipulator to plan manipulator trajectories to minimize base reactions. In this paper we develop a global approach for minimizing the magnitude of the base reactions for kinematically redundant manipulators which integrates the Partitioned Jacobian method of redundancy resolution, a 4-3-4 joint-trajectory representation and the minimization of a cost function which is the time-integral of the magnitude of the base reactions. We also compare the global approach with a local approach developed earlier for the case of point-to-point motion of a three degree-of-freedom planar manipulator with one redundant degree-of-freedom. The results of study show that the global approach is more effective in reducing and smoothing the base force while the local approach is superior in reducing the base moment.
A Mechanics-Based Computer Algorithm for Displaying the Margin of Static Stability in Quadruped Walking Machines
Authors: Davidson J. K. , Schweitzer G.
Published: April 2021

The subject of this paper is the application of the mechanics of static stability to determine the potential upset of computer-controlled quadruped walking vehicles which are under development for use in very uneven terrain by the European construction and forestry industries. The margin of static stability is measured using normalized values for virtual power, each value corresponding to the motion about an axis of rotation which is associated with one mode of potential overturning. Static stability is treated for spatial positioning of the feet and for both three and four feet in contact with the ground. The inertial loads from a heavy tool, such as an excavating arm, are included in a quasi-static manner. The values for normalized virtual power are then related to a geometrical description of stability of the vehicle as if it were operating on level ground. Recommendations are made for visually displaying the geometrical description to the operator of the machine. The required measurements of force and position are listed.
A Unified Approach to the Kinematic Analysis of Joint Clearances and Link Length Tolerances for Determination of the Rotational and Positional Accuracy of Planar Mechanisms
Authors: Hoeltzel D. A. , Chiang W.-H.
Published: April 2021

A unified approach to the kinematic analysis of joint clearances and link length tolerances in general mechanisms is presented, expressly with the purpose of predicting the error in both rotational and positional accuracy of planar and spatial mechanisms. Rather than applying stochastic estimation or deterministically-based approximations based on a Taylor series expansion approach, this new method obtains the exact mechanical error based on a combination of approaches including the principle of virtual work, pertinent geometrical relations, and kinetostatic analysis. Computer–based kinematic designs for the Schmidt coupling, a parallel–jaw straight–line path generator and a sinusoidal function generator have been included as representative real–world design examples, for determination of their maximum mechanical error and error sensitivity to link length tolerances and joint clearances.

The computer–aided approach presented in this paper is particularly attuned to the needs and requirements of industrial precision mechanism designers in providing definitive information, which is directly applicable to the determination of kinematic error effects due to manufacturing tolerances, on the accuracy of mechanisms.
Topological Synthesis and Analysis of Geared Linkages Based on Matrix Powers
Authors: Olson D. G. , Erdman A. G. , Riley D. R.
Published: April 2021

A new method for transforming pin-jointed kinematic chains into geared linkages is introduced. The method utilizes the graph representation in the form of the adjacency matrix and the “degree matrix” [20], and the powers of these matrices. The method involves first determining the feasible locations for assigning gear pairs in a kinematic chain, followed by determining which of the choices are distinct, and finally, determining the distinct possible ways of assigning the ground link for each distinct “geared kinematic chain” so formed. Because the method is based on matrix manipulations and does not rely on visual inspection, it is easily implemented on a digital computer. The method is applied to an example class of geared mechanism, the single-dof geared seven-bar linkages.
Effect of Bearing Clearance on Cardan-Joint Kinematics
Authors: Fischer I. S. , Liu M. C.
Published: April 2021

The effect of radial bearing clearance at the intermediate joints of a Cardan-type universal joint has been investigated. It is found that errors in displacement at the output and also intermediate joints occur, and that their amplitudes have a linear relationship to the magnitudes of the radial bearing clearances.
A New Graph Representation for the Automatic Kinematic Analysis of Planetary Spur-Gear Trains
Authors: Hsu C.-H. , Lam K. T.
Published: April 2021

The purpose of this paper is to propose a new graph representation to represent the kinematic structure of a planetary spur-gear train efficiently. Based on the graph representation, the kinematic analysis of planetary spur-gear trains is largely simplified. An interactive computer program is developed for the kinematic analysis of planetary spur-gear trains with any numbers of degrees of freedom. By only inputting the graph representation of a planetary spur-gear trains and the data of the mating gear pairs, all possible fundamental circuits are determined and the rotational displacement equations are derived and solved automatically.
Four-Bar Path Generation Synthesis by a Continuation Method
Authors: Subbian T. , Flugrad D. R.
Published: April 2021

A different approach for the synthesis of four bar planar path generating mechanisms is presented. A continuation method is used to solve the system of nonlinear equations derived for the path generating problem. A brief description of the method is provided followed by the development of equations representing the four bar linkage. The implementation of the method for five position path generation is discussed in detail and the solutions for two examples are presented.