bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Model of Diesel Engine Combustion Process: Part 1 — Theory
Authors: Danov Stanislav N. , Gupta Ashwani K.
Published: February 2021

A mathematical model of combustion process in a diesel engine has been developed. The combustion process is considered to have both the premixed and diffusion flame. The combustion of fuel vaporized during the self-ignition delay period is modeled according to the conditions of premixed flame. A kinetic differential equation has been formulated for modeling this kind of combustion. The combustion of fuel during the injection process is modeled according to the theory of diffusion flames. This process is strongly influenced by processes of fuel injection, vaporization and diffusion. The atomization process is taken into account by means of the Sauter mean diameter (SMD) of fuel droplets. The instantaneous vaporization rate is defined by the current values of temperature, pressure, concentration of fuel vapors and the mean fuel droplet size in terms of the SMD. The mathematical model includes differential equations describing the processes of fuel injection, vaporization, heat transfer and combustion in both the premixed and diffusion flame that takes place in the engine cylinder. The above equations are solved together with the differential equation of the first law of thermodynamics expressing the energy conversion process in the cylinder of diesel engine. The fourth-order Runge-Kutta method is applied for obtaining numerical solution of the system of differential equations. The analysis is performed on a PC using FORTRAN 90. The results have been simulated for a marine direct injection (DI) diesel engine (Model Silzer 6RLB-66) having a cylinder bore diameter of 0.66 m, and stroke of 1.4 m. The amount of fuel used in this engine during the experiments is 0.03785 kg per cycle per cylinder. The numerical experiments have been carried out for the effect of duration of fuel injection and the beginning of fuel injection (expressed in terms of degrees of crank angle before TDC) on the subsequent combustion parameters and the integral indicator parameters of the engine.
Numerical Solution of the Flow Between Two Disks
Authors: Ghaly Wahid S. , Vatistas Georgios H.
Published: February 2021

This paper deals with the numerical solutions of converging and diverging flows, between two disks. The results are obtained by solving a nonlinear third order ordinary differential equation using a modified shooting method. The governing equation is written as a system of three nonlinear first order ODE’s and the resulting system is solved as an initial value problem via the Runge-Kutta method. The results are given in terms of velocity profiles and static pressure distributions. These are compared with previously reported experimental data obtained by others.
Mesh Construction Dedicated to a Multi-Representation for Structure Analysis Based on an Initial Polyhedral Geometry
Authors: Maza Stéphane , Léon Jean-Claude , Noël Frédéric
Published: February 2021

The aim of this paper is to present the first part of a new approach devoted to the generation of a data structure and operators for the hierarchical representation of 3D polyhedra. Here are described the treatments which allow to create some of the elements of this hierarchical model. At first, partitions of the initial polyhedron are mapped into planar connex hulls. Then, these domains are used like a piecewise parametric 2D space for subsequent polyhedra generations. In order to create such a mapping, the initial 3D polyhedron is partitioned to produce simply convex subsets which can be submitted to the parametrization process. The next step consists in the generation of a minimum representation of the initial 3D polyhedron. This representation forms the root of the hierarchical data structure. Then, the mapping obtained allows the construction of various polyhedral representations of the initial geometry. Criteria related to 3D parameters are used to generate the range of polyhedra. The reverse mapping (from 2D to 3D) helps reduce the computing cost required to generate 3D polyhedra. Each 3D polyhedron generation is carried out under 3D geometric criteria depending on the context. i.e.: structural analysis, levels of details of a geometric model, ... Among the goals of the hierarchical data structure, the unification and the inter dependency of the meshes required to carry out the structural analysis of a part occupies a central position.
Evaluation of Errors Resulting From Nusselt Number Assumptions in Coal Combustion Modeling
Authors: Sampath Ramanathan , Maloney Daniel J. , Zondlo John W. , Monazam Esmail R.
Published: February 2021

The heat transfer model, for single coal particles subjected to rapid heating, developed in our previous studies assumed the steady state Nusselt number value of 2.0 in the analysis. However, in the case where temperature is changing very rapidly in the boundary layer, the steady state assumption may no longer be valid. In the present study, an unsteady state Nusselt number equation was developed near the boundary layer of the particle and was incorporated into the analysis. The temperature history for a 125 μm (diameter) carbon sphere with a density of 0.95 g/cm3 was modeled using this equation for a heat input of 1406 W/cm2. The temperature history for the same particle and input flux was also predicted using Nu = 2. It was found that the unsteady state equation does not improve the model performance. However, it does keep the theory more consistent with the experiment.
Kalman Filtering: A New Strategy for Building Global Approximations for Structural Optimization
Authors: Braibant Vincent , Leménager E. , Bouet Th.
Published: February 2021

This paper discusses the use of Kalman filters as a new approach for building global approximations. Basic ideas and procedures of Kalman filters are first recalled. Next, key elements of how to implement the method for design problems are described. Finally, in order to evaluate the performance of the approach, an inverse problem which consists in optimizing a warhead with respect to constraints on the resulting projectile is solved. It is shown that global approximations are convenient for the solution of complex optimization problems and that Kalman filtering techniques appear a well suited strategy for the construction of global approximations in structural optimization.
Trade-Offs in Robust Engineering Design
Authors: Gold Steven , Krishnamurty Sundar
Published: February 2021

The ever increasing demands for improved performance in engineering design from an overall perspective requires a sophisticated automated design generation strategy that can effectively and efficiently incorporate concepts of uncertainty, quality and robustness into design. Engineering design optimization approaches that typically require modeling the problem in a single objective form become inadequate to address these multiple set of requirements. Instead, this research presents an alternative robust multiple-criteria based design approach. In this approach, decision models are formulated using utility functions that quantitatively represent designers’ subjective preferences and optimal solutions are then determined in a statistical exploration based iterative design of experiment set-up. The resulting Trade-off Based Robust Engineering Design (TRED) method is illustrated with the aid of an example design problem. The results indicate that the TRED approach can be expected to address some of the important issues associated with the engineering design of problems including tolerances, quality control and uncertainties.
Consistent Updating of Constrained Parametric Curves in a Variational Design System
Authors: Huffaker A. Vincent , Charny Leonid
Published: February 2021

This paper demonstrates techniques to allow relations on parametric curves in a variational design system. Constraints on the curves, which are normally represented as constrained nonlinear optimization problems, are reduced to systems of nonlinear equations (using the necessary conditions of the NLP). Additional degrees of freedom are constrained through fairing the curve and the resulting NLP is also reduced to its necessary conditions. Although the solution set of the necessary conditions contains the optimum, it contains many other solutions as well. The COAST design consistency algorithm is reviewed and then extended to handle consistency when constraints take the form of relations between objects. An example is given involving distance constraints on Bezier curves.
Task Structuring Toward Computational Approaches to Product Variety Design
Authors: Fujita Kikuo , Ishii Kosuke
Published: February 2021

This paper discusses the direction toward computational approaches for product variety design. Product variety design here refers to an engineering challenge for designing multiple models simultaneously. This paper defines the formal representation of product variety design, and proposes a structure of design tasks involved in product variety. The analysis reveals several characteristics of product variety design, and identifies unique and essential tasks for simultaneously designing multiple models: correlation analysis, competing against system constraints, control variable selection, coverage distribution and combination selection. The paper closes with the scenario toward computational methods and difficulties to overcome for product variety optimization.
Fuzzy Tolerance Analysis of 3-D Mechanical Assemblies
Authors: Srikanth K. , Liou F. W. , Balakrishnan S. N.
Published: February 2021

Tolerance design is interdisciplinary in nature and is characterized by a highly uncertain environment. In recent years, fuzzy logic has appeared as a credible alternative for tolerance design. In this paper a fuzzy based tolerance representation scheme is presented to model three dimensional (3-D) tolerances. With this representation, relative assembly tolerance constraints can be expressed. A fuzzy tolerance generation and assignment process for assembly is discussed. Fuzzy tolerance equations are generated for 3-D assembly considerations. Manufacturing process information, along with uncertain cost information modeled in fuzzy terms, is added to the system to arrive at a cost-optimal tolerance assignment.
SphinxPC: An Implementation of Four Position Synthesis for Planar and Spherical 4R Linkages
Authors: Ruth D. Alan , McCarthy J. Michael
Published: February 2021

This paper presents the basic theory and algorithmic structure of a design system that implements four position synthesis for both planar and spherical four bar linkages. The formalism uses complex numbers to define the equation of a planar triangle and quaternions to define the equation of a spherical triangle. These equations form the basis of a parallel implementation of these design theories. The theory and major functional components of SphinxPC are described and examples are presented.
Xlinkage: A Web-Based Analysis and Simulation Tool for Planar Mechanical Systems
Authors: Van Katwyk Kirk , Cheng Harry H.
Published: February 2021

Web-based network computing is fundamentally different from domain-based computing. Web-based network computing is accomplished through execution of a collection of small programs across different computer platforms on a network. Most tools currently used for analysis and simulation of mechanical systems, such as ADAMS and I-DEAS, are developed for domain specific applications. These programs are very large with significant initialization overhead and a complicated user interface. They are, therefore, not suitable for analysis of mechanical systems through the World Wide Web. In this paper, a new Web-based paradigm for analysis and simulation of mechanical systems will be presented. Web-based analysis of mechanical systems is not optimally achieved through large programs. Instead, it is accomplished through a collection of small utilities executed on different computers across a network. These small utilities are developed using the CH language environment, a superset of C for network computing. Using a Web browser, small programs can be generated by a Web server on the fly and downloaded through the network, and executed on a local client machine. The details about the implementation of the Xlinkage program for Web-based analysis and simulation of planar mechanical systems as well as its integration with analysis utilities and the WWW will be described in this paper. Because of its modular nature, our Web-based system is simple to use and maintain. It is especially suitable for distance learning. The system has been used as a teaching and learning tool at the University of California, Davis. Mechanism design utilities and the Xlinkage program are available for downloading on the WWW at the URL address http://iel.ucdavis.edu/design/.
Placement of a Robotic Manipulator for Traversing a Path in Minimum Time
Authors: Kathari Murali , Trabia Mohamed B.
Published: February 2021

Productivity of a robotic manipulator depends to a large extent on the time it takes to traverse a path. The path traversal time is in turn a dependent, among several other factors, on the manipulator location within the workcell. This paper defines the robot base locus boundaries when the end-effector path is prescribed. Effects of joint limits and obstacle presence on the robot base locus are also considered. The proposed algorithm searches the robot base locus to determine the robot base location that yields the minimum path traversal time, location subject to the robot joint torque constraints, using nonlinear programming techniques.
Kinematic Analysis of a Three-DOF Parallel Mechanism for Telescope Applications
Authors: Carretero J. A. , Nahon M. , Buckham B. , Gosselin C. M.
Published: February 2021

This paper presents a kinematic analysis of a three-degree-of-freedom parallel mechanism intended for use as a telescope mirror focussing device. The construction of the mechanism is first described and its forward and inverse kinematics solutions are derived. Because the mechanism has only three degrees of freedom, constraint equations must be generated to describe the inter-relationship between the six Cartesian coordinates which describe the position and orientation of the moving platform. Once these constraints are incorporated into the kinematics model, a constrained Jacobian matrix is obtained. The stiffness and dexterity properties of the mechanism are then determined based on this Jacobian matrix. The mechanism is shown to exhibit desirable properties in the region of its workspace of interest in the telescope focussing application.
Formation of Geometric Tolerance Zones for Polyhedral Objects
Authors: Roy Utpal , Li Bing
Published: February 2021

This paper presents a scheme for establishing geometric tolerance zones for polyhedral objects in solid modelers. The proposed scheme is based on a surface-based variational model. Variations are applied to a part model by varying each surface’s model variables. Those model variables are constrained by some algebraic relations derived from the specified geometric tolerances. For size tolerance, two types of tolerance zones are considered in order to reflect two different types of size tolerances. For any other geometric tolerance (form, orientation or positional), the resultant tolerance zone is defined by the combination of size tolerance and that particular geometric tolerance specifications. Appropriate algebraic constraints (on the model variables) are finally used to establish the tolerance zone boundaries in the surface-based variational model.
Shared Information Structures for Product Design and Process Simulation in Design for the Life-Cycle
Authors: Hooks Keith , Bras Bert , Rosen David W.
Published: February 2021

In modern design, life cycle concerns such as recycling and service are receiving increased attention. One of our goals, as researchers, is to develop the tools, methods, and techniques to facilitate design for the life cycle. In this paper, we develop a plan for helping the designer learn more about the life cycle processes that a product may undergo through the integration of process simulation into the product design environment. The architecture of our design system and our proposed extensions through the integration of process simulation are explained. In addition, we use the example of a disassembly process to gain an understanding of the information requirements for two types of process simulations. Secondly, using the knowledge acquired from the motivating example, we develop a shared information structure that will facilitate the integration of process simulation within the product design environment. Finally, we present the case-study of a single-use camera to outline the implementation of the shared information model and to highlight the results and benefits of doing so.
Explicit Algorithm for Robot Manipulator Dual Dynamics
Authors: Brodsky Vladimir , Shoham Moshe
Published: February 2021

Kinematicians have used dual numbers to obtain rigid body kinematics in a compact three-dimensional form by substituting dual for real numbers in the equation of rotational motion. No such simple relation, known as ‘principle of transference’, existed however, for dynamics. The commonly used inertia binor by which dual momentum is calculated, raises the dual dynamic equations to six dimensions. In fact, the inertia binor does not act on the dual vector as a whole, but rather on its real and dual parts as two distinct real vectors.

The recently introduced dual mass operator can serve as the missing link between the dual kinematic and the dual dynamic equations. It gives the mass a dual property which has a complementary sense of Clifford’s dual unit, namely, it reduces a motor to a rotor proportional to the vector part of the motor. With this definition of mass, the same equation of momentum and its time derivative, which holds for a linear motion, holds for both linear and angular motion of a rigid body if dual force, dual velocity, and dual inertia replace their real counterparts.

Application of the dual inertia operator and motor transformation rule permits derivation of an explicit dynamic algorithm of a serial manipulator which has several advantages over the more conventional Newton-Euler and Lagrange formulations. Firstly, all the expressions of this algorithm are explicit parts of the dual transformation matrices and the constant link-attached inertia parameters. Secondly, this algorithm is an explicit, not a recursive one and does not require derivative of any one of its terms. It rather gives all coefficients of the dynamic equations in a simple and compact form of determinants and vector scalar product.
Intelligent Process Planning Implemented As an Integrated Module of CIM
Authors: Sormaz Dusan N. , Khoshnevis Behrokh
Published: February 2021

In this paper we describe an architecture of a new integrative process planning system as a part of computer integrated manufacturing research system. The process planning procedure is comprised of three phases: feature completion, process selection and process sequencing. We applied a knowledge-based approach to feature completion and process selection, and the space search algorithm for process sequencing. Description of these phases is provided and underlying knowledge representation explained. Integration between the process planning, on the one side, and CAD and scheduling, on the other, is discussed. System implementation has been described and several examples of the system execution are shown.
An Integrated DFM System for Milling
Authors: Krishnan Subramanian , Magrab Edward B.
Published: February 2021

An integrated design for manufacture system for milling is developed by introducing a fundamental manufacturing entity for milling (FMEM), which represents a volume to be machined. A part is created by subtracting a user created set of FMEMs from a rectangular prismatic stock. Manufacturability evaluation is done in two stages: (1) after creating each FMEM; and (2) after placing and subtracting the volume from the stock. It is shown that the commonly used 2½ -D features used to mill a part such as slots, pockets and holes are a subset of the FMEM. Furthermore, all specific shapes of the general FMEM are represented by one compact data structure. It is demonstrated that using process specific entities greatly simplifies manufacturability evaluation, which makes it possible to base the geometric reasoning algorithms on the entity’s most general profile rather than on only a set of specific shapes. A new approach using the FMEMs is presented for generating an integrated process and fixture plan with a minimum number of setup and tool changes. The advantages of using the process specific entities approach for design and manufacturability analysis over the feature recognition approach and feature based approach are enumerated.
Parting Direction and Parting Planes for the CAD/CAM of Plastic Injection Molds
Authors: Urabe Kiyoshi , Wright Paul K.
Published: February 2021

We describe a plastic injection mold making agent that is part of a domain unified computer-aided design environment. This environment enables concurrent design of the “to-be-molded” part, by facilitating communication between electrical and mechanical engineering CAD tools. Once the design is completed and certain constraints are satisfied, the design is passed to the mold making agent. After the designer inputs some mold parameters, the mold agent automatically determines the parting direction and parting plane, and generates the mold halves. This is achieved by applying a set of heuristic rules on the part geometry. These rules, design constraints, and methods used to generate the mold are discussed. Resulting mold halves have been fabricated on a 3 axis milling machine using CAD / CAPP / CAM tools described in this paper. Examples of aluminum molds and sample output from the mold making agent are presented.
A Modular Method for Representing Product Life-Cycles
Authors: Jackson Paul , Wallace David R.
Published: February 2021

This paper describes an approach for modeling product life-cycles to create time-dependent inventories for use in environmental impact assessment. A general process module is defined relating resource inputs and outflows, based upon an embedded mathematical model. Then, a parametric model to represent the average performance of manufacturing processes is proposed and used within modules. Different parameter values may be used to represent a variety of life-cycle processes. Individual modules are combined to form product life-cycle networks. Designers may specify the required system output (product demand) as a function of time and the integrated network calculates the necessary time-dependent resource flows throughout the network.
Robust Design for Recyclability Using Demanufacturing Complexity Metrics
Authors: Lee Burton H. , Rhee Seung , Ishii Kosuke
Published: February 2021

This paper proposes a design chart incorporating demanufacturing complexity metrics in robust design for recyclability. The proposed recyclability map relates sort complexity and material recovery efficiency for major subassemblies. The map helps designers to reduce product retirement costs and scrap through the appropriate selection of design modularity, material selection and disassembly strategy. Our method focuses on the dismantling process associated with multiple product families and generations and incorporates changes in recycling process technology capabilities. The recyclability map allows designers to understand the effects of uncertainties in product recycling and helps them to reach a strategy that is insensitive to these changes. The paper uses recycling of an inkjet printer as a validation example.
Comparison of US and European Bolt Load Calculation Methods vs. Bolt Load Predictions From a Finite Element Model
Authors: Grote Karl-H. , Westberg Hans E.
Published: February 2021

The bolted joint is by far the most used connector and joint in mechanical design applications. The authors have years of experience in the calculation of these joints in Europe and the United States. This paper compares the results from currently used bolt load calculation methods in Germany ([1,2,3,], VDI-2230) and methods used in the USA and Canada to the results obtained from a finite element model of a bolted joint.

For detailed information see [4].
Design for Variety: Development of Complexity Indices and Design Charts
Authors: Martin Mark V. , Ishii Kosuke
Published: February 2021

This paper describes methods to help project leaders and engineers manage the costs of providing variety to the market. As companies look for ways to stay competitive in the global marketplace, the concept of mass customization has appeared as a potential advantage. Armed with new manufacturing and information technologies, companies are trying to determine the amount of variety that they should offer to optimize profits. Our Design for Variety (DFV) research focuses on methodologies which will help companies quantify the costs of providing variety and will qualitatively guide designers in developing products that incur minimum variety costs. The proposed tools incorporate quantitative indices and qualitative design charts. Examples from electronics and automotive industries illustrate the utility of the tools.
Haptic Interfacing for Virtual Prototyping of Mechanical CAD Designs
Authors: Hollerbach John M. , Cohen Elaine , Thompson William , Freier Rodney , Johnson David , Nahvi Ali , Nelson Don , Thompson Thomas V.
Published: February 2021

A network-based real-time control architecture has been developed which integrates a haptic interface (the Sarcos Dextrous Arm Master) with an advanced CAD modeling system (Utah’s Alpha_1). New algorithms have been developed and tested for surface proximity testing, fast updates to local closest point on a surface, and smooth transitions between surfaces. The combination of these new algorithms with the haptic interface and CAD modeling system permits a user to actively touch and manipulate virtual parts as well as passively view them on a CRT screen.
Networked Haptic Interfaces for Distant Redesign and Review of Free-Form Surfaces
Authors: Kanai Satoshi , Takahashi Hidetomo , Kishinami Takeshi
Published: February 2021

The review and redesign of a freeform surface model, a process known as approval, is the final and indispensable stage in advancing a model from style designer to die manufacturer. This paper proposes a collaborative system for the review, redesign, and exchange of data on freeform surface models over a network, with the goal of improving the efficiency of the approval process among distant sites. First we analyze the work-flow of the long-distance approval. Then, in order to eliminate the physical model, we present a 3DOF haptic interface (force display) that accurately renders the feel of the freeform surface in great detail. Finally, we describe the architecture of the intra-network software that manages each step of the approval while maintaining consistency between the numerous versions of the surface models. The experimental results of a 3DOF communication between Tokyo and Sapporo and the subsequent review and redesign of the system are also shown.
A Framework for Designing Component Shapes in a Virtual Reality Environment
Authors: Dani Tushar H. , Gadh Rajit
Published: February 2021

Despite advances in Computer-Aided Design (CAD) and the evolution of the graphical user interfaces, rapid creation, editing and visualization of three-dimensional (3D) shapes remains a tedious task. Though the availability of Virtual Reality (VR)-based systems allows enhanced three-dimensional interaction and visualization, the use of VR for ab initio shape design, as opposed to ‘importing’ models from existing CAD systems, is a relatively new area of research. Of interest are computer-human interaction issues and the design and geometric tools for shape modeling in a Virtual Environment (VE). The focus of this paper is on the latter i.e. in defining the geometric tools required for a VR-CAD system and in describing a framework that meets those requirements. This framework, the Virtual Design Software Framework (VDSF) consists of the interaction and design tools, and an underlying geometric engine that provides the representation and algorithms required by these tools. The geometric engine called the Virtual Modeler uses a graph-based representation (Shape-Graph) for modeling the shapes created by the user. The Shape-Graph facilitates interactive editing by localizing the effect of editing operations and in addition provides constraint-based design and editing mechanisms that are useful in a 3D interactive virtual environment. The paper concludes with a description of the prototype system, called the Virtual Design Studio (VDS), that is currently being implemented.1.
An Activity-Based Life-Cycle Assessment Method
Authors: Emblemsvåg Jan , Bras Bert
Published: February 2021

In this paper, a new activity-based method for the concurrent assessment and tracing of costs, energy consumption and waste generation for usage in Life-Cycle Design is presented. The method is based on Activity-Based Costing (ABC). By utilizing ABC we are able to assess and trace accurately overhead — and direct costs, energy and waste generation. The inherent uncertainty is modeled in terms of fuzzy numbers, but solved numerically using the Monte Carlo simulation technique, which allows us to perform a sensitivity analysis. This enables us to not only estimate the costs, energy consumption and waste generation, but also trace the largest contributors. The capability to trace the contributors is perhaps the most significant feature — especially when the method is employed for design. To illustrate the usage of this method, a simple case study is provided in which we explore the life-span costs, energy consumption and waste generation of a oil/gas exploration platofrm supply vessel operating in the North Sea.
The N-Dim Approach to Creating Design Support Systems
Authors: Subrahmanian Eswaran , Reich Yoram , Konda Suresh L. , Dutoit Allen , Cunningham Douglas , Patrick Robert , Thomas Mark , Westerberg Arthur W.
Published: February 2021

Creating practical design support systems is a complex design endeavor. We approach it with an evolutionary process, one that studies the design information flow then builds and tests information management support systems. Through our experience with industrial partners we have evolved this process into a set of methods and tools that support these methods. We have evolved an infrastructure called n-dim, that is composed of a small number of building blocks that can be composed in ways that match the complexity of design contexts and work. We have developed this infrastructure to be highly flexible so as to allow us to conduct this evolutionary process in a practical project setting.
Modelling the Information Flows in Engineering Design: A New Paradigm
Authors: Boston Oliver P. , Culley Stephen J. , McMahon Christopher A.
Published: February 2021

The work presented within this paper represents a step towards providing the understanding necessary to improve support for engineering designers undertaking their day-to-day activities. In particular, it presents an evolving technique for both modelling and managing the information flows between the design functions of customers and suppliers engaged in product development. The technique, termed the Multifunctional Information Model (MIM), provides an easy to read, continually updateable record of bilateral information exchanges, mapped onto the design process phases. It was derived from observations of engineering designers in practice, and has subsequently been applied to a number of case-studies.

The paper first considers the required characteristics of such a model, and evaluates a number of the formal modelling techniques against these. It then presents a ‘walk-through’ of the development of MIM, followed by an overview of its implementation in a software application.
Collaborative, Sequential, and Isolated Decisions in Design
Authors: Lewis Kemper , Mistree Farrokh
Published: February 2021

The Massachusetts Institute of Technology (MIT) Commission on Industrial Productivity, in their report Made in America, found that six recurring weaknesses were hampering American manufacturing industries. The two weaknesses most relevant to product development were 1) technological weakness in development and production, and 2) failures in cooperation. The remedies to these weaknesses are considered the essential twin pillars of CE: 1) improved development process, and 2) closer cooperation. In the MIT report, it is recognized that total cooperation among teams in a CE environment is rare in American industry, while the majority of the design research in mathematically modeling CE has assumed total cooperation. In this paper, we present mathematical constructs, based on game theoretic principles, to model degrees of collaboration characterized by approximate cooperation, sequential decision making and isolation. The design of a pressure vessel and a passenger aircraft are included as illustrative examples.
The Applicability of the Axiomatic and Decision-Based Design Equations in Variant Design
Authors: Marston Matthew , Bras Bert , Mistree Farrokh
Published: February 2021

For sometime Nam Suh’s axiomatic design has been a view of design science; a view in which design science is seen as a process subject to a set of rules or governing, rational axioms. The two principal limitations of axiomatic design as espoused by Suh are 1) its inability to be used at every stage in a design process, and 2) the lack of supporting tools for designing with the axioms. It is our contention that in order to improve the existing axiomatic approach to design, a new model for designing is needed. In this paper we offer a fundamental algebraic model for design, the Decision-Based Design equations, that encompasses Suh’s axiomatic design and is applicable at any stage in a design process.
A Set-Based System for Eliminating Infeasible Designs in Engineering Problems Dominated by Uncertainty
Authors: Finch William W. , Ward Allen C.
Published: February 2021

This paper gives an overview of a system which eliminates infeasible designs from engineering design problems dominated by multiple sources of uncertainty. It outlines methods for representing constraints on sets of values for design parameters using quantified relations, a special class of predicate logic expressions which express some of the causal information inherent in engineering systems. The paper extends constraint satisfaction techniques and describes elimination algorithms that operate on quantified relations and catalogs of toleranced or adjustable parts. It demonstrates the utility of these tools on a simple electronic circuit, and describes their implementation and test in a prototype software tool.
Using Key Characteristics to Balance Cost and Quality During Product Development
Authors: Thornton Anna C.
Published: February 2021

Corporations are spending significant resources to reduce the effect of manufacturing variation on product quality as well as adopt lower cost manufacturing and assembly technologies to reduce the end costs in product development. However, to ensure that these investments have a positive return, efforts must be made to put resources into those areas where there will be the largest return. This paper describes a formalized method to make these decisions. The analysis focuses the tradeoff studies on the Key Characteristics (KCs) of the product. KCs, in use in a variety of industries, are the product features that are most sensitive to existing manufacturing and process variation and will affect the end quality of the product. Two examples from the aircraft manufacturing environment are used describe the application of the proposed methods.
Vibration Control of a Distributed Axially Moving String Using Two Actuators
Authors: de Queiroz M. S. , Dawson D. M. , Rahn C. D. , Zhang F.
Published: February 2021

In this paper, we consider the problem of regulating the displacement of an axial moving string using a control force and a control torque applied to the string via a mechanical guide. Given the hybrid model of the web system (i.e., distributed parameter field equation coupled to a discrete actuator equation), a Lyapunov-type analysis is utilized to design exact model knowledge and adaptive control laws that exponentially and asymptotically stabilize the string displacement, respectively. Dynamic simulation results demonstrate the vibration damping provided by the control strategy.
Analysis of Acoustical Properties of a Gear Mechanism
Authors: Podzharov Evgueni I.
Published: February 2021

For an analysis of the acoustical properties of a multistage gear mechanism, a technique was used that combines a dynamic calculation of the mechanism as multimass multicoupling system and the SEA method for the calculation of acoustical energy. The dynamic calculation was used to determine the energy introduced into the mechanism’s gear meshes and the energy transmitted to the housing. The SEA method was used for the calculation of propagation of acoustical energy in the structure and its radiation in the surrounding space. Such a combination permits us to utilize the advantage of dynamic calculation accurately describing the mechanism’s performance and the SEA method for describing an acoustical model having the elements of high mode density in a wide frequency range. Some useful results were obtained which permit us to reduce noise level of the mechanism.
In-Plane Stick-Slip Vibration on the Surface of a Flexible Disc Clamped Between Elastic Sliders
Authors: Ouyang Huajiang , Mottershead J. E. , Cartmell M. P. , Friswell M. I.
Published: February 2021

The in-plane stick-slip vibration of two slider systems which are driven together around the surfaces of either side of a flexible vibrating disc, and the induced transverse vibration of the disc, are investigated. The disc is taken to be an elastic annular plate and each slider has flexibility in the circumferential (in-plane) and transverse directions. The static friction coefficient is assumed to be higher than the kinetic friction coefficient. Because of the friction force acting between the disc and the slider systems, the sliders will oscillate in the stick-slip mode in the plane of the disc. The transverse vibration induced by the oscillating sliders will change the normal forces of the slider systems acting on the disc, which in turn will change the in-plane oscillation of the sliders. Therefore, the in-plane oscillation of the sliders and the transverse vibration of the disc are coupled. For different values of system parameters, the coupled in-plane oscillation of the sliders and transverse vibration of the disc will exhibit quasi-periodic as well as chaotic behaviour.

Typical patterns of chaotic vibration of the slider systems and of the disc are presented in graphs to illustrate the special behaviour of this non-smooth, nonlinear dynamical system. The physical model represents a car disc brakes.
Analysis of Stick-Slip Motion in Coulomb Damped Systems Using Variable Structure System Theory
Authors: Ferri Aldo A. , Heck Bonnie S.
Published: February 2021

The numerical simulation and control design of many systems is hampered by the presence of dry (Coulombic) friction. In particular, the discontinuous nature of the friction law leads to computational difficulties whenever sticking occurs across the frictional interfaces. This paper uses results from Variable Structure System (VSS) theory to develop a model useful for simulating stick-slip motion in a generic system with multiple frictional interfaces. The Variable Structure framework is also used to analyze the errors incurred in the new simulation model. A second approach, motivated by the alleviation of chatter in VSS systems, uses a saturation-type nonlinearity to represent the frictional interface. The accuracy of this approach is analyzed using VSS and singular perturbation theory. The accuracy and numerical efficiency of each method is demonstrated in two numerical examples.
Influence of Internal Structures of High Modal Density on Shell’s Radiation
Authors: Oddo Lionel , Laulagnet Bernard , Guyader Jean-louis
Published: February 2021

The aim of this paper is to study the sound radiation by a cylindrical shell internally coupled with mechanical structures of high modal density. The model is based on a mobility technique. The numerical results show a smoothing of the cylinder’s velocity and radiation spectra associated with an increase of the apparent damping. The use of the S.E.A. method allows us to calculate an additional structural damping of the shell, equivalent to the effect of the internal structures.
Vibroacoustic Source Identification, From Measured Structure Response and Resolution of the Inverse Problem
Authors: Pezerat C. , Guyader J. L.
Published: February 2021

This paper is concerned with the localization of input forces in a two-dimensional system using an inverse vibration method. Using the measured flexural displacements of a plate, one can determine the location and amplitude of the external forces exciting the plate. As in all inverse problems, difficulties arise due to the sensitivity to measurement uncertainties, so that small errors in the measurements could introduce a high noise on the result. An analytical method is developed and involves local estimation of the force distribution using a finite difference scheme, a spatial window and a numerical wavenumber filter. This method needs only the equation of motion of the plate and has the advantage that it can be used with unknown boudary conditions. However, mechanical sources near the boundaries of structures cannot be localized. A numerical simulation and experimental results are shown. The numerical simulation exhibits the influence of noisy displacement measurements on localization. Experiments are described where the localization of an external source and the determination of coupling forces between a plate and a stiffener are accurately found.
Cavitation Driven Impact in a Hydraulic Piston Pump: A Theoretical and Experimental Investigation
Authors: Manhartsgruber Bernhard , Scheidl R.
Published: February 2021

The occurrence of cavitation in a huge hydraulic supply system of a rolling mill which caused a severe defect in an axial piston pump is investigated by a mathematical model of the complex suction system. It comprises wave propagation in pipes and hoses, a detailed model of the pump including each of its nine cylinders, cavitation therein, the charge and discharge processes of these cylinders with the intake duct, and several accessories influencing the hydraulic processes. Results obtained by this model are compared with on-site experiments. Countermeasures which have been proposed are evaluated by our model and their practical examination is reported. Due to the strong nonlinearity of cavitation the dynamical system shows two attracting limit sets, one with and one without cavitation. The operating conditions of the original supply system cause startup conditions which do not lie in the basin of attraction of the non-cavitating attractor.
Dynamics of Distributed Impact Dampers
Authors: King Melvin E. , Sandri Guido
Published: February 2021

In this work, the dynamics of spatially distributed impact dampers are investigated. Typical impact damper configurations consist of a single, rigid mass which moves freely within a cavity that is attached to a lightly damped structure. By tuning the damper’s mass and the cavity’s length (gap-size), the maximum displacement of the structure may be significantly reduced due to the resulting intermittent collisions. Several modifications to the classical impact damper design have been considered in the literature, including (i) multiple-unit dampers, and (ii) granular impact dampers. Both designs have been found to effectively attenuate resonant responses, while simultaneously reducing the severe impact loads, accelerations and noise levels associated with a single-unit damper. An extension of the multiple-unit damper configuration is considered in the present work. The configuration under consideration (referred to as a distributed impact damper) incorporates a number of non-identical single-unit dampers. Whereas multiple-unit dampers composed of identical elements may be tuned to a specified resonant frequency, the proposed distributed impact damper is expected to provide significant attenuation over broad frequency bands. The present work focuses on developing analytical tools with which to study the dynamics of distributed impact dampers. In this regard, methods from non-equilibrium statistical mechanics, including correlation hierarchy, will be used to develop statistical models of the distributed impact damper. Successful completion of this work is expected to provide significant insight into the dynamics of distributed impact dampers, leading to the future development of novel broad-band damping and shock isolation designs.
Piecewise Linear Systems With Time Varying Coefficients
Authors: Natsiavas S. , Theodossiades S.
Published: February 2021

A new method is presented for determining periodic steady state response of piecewise linear dynamical systems with time varying coefficients. As an example mechanical model, a gear-pair system with backlash is examined, under the action of a constant torque. Originally, some useful insight is gained on the type of motions expected by investigating the response of a weakly nonlinear Mathieu-Duffing oscillator, subjected to a constant external load. The information obtained is then used in seeking the appropriate form of approximate periodic solutions of the piecewise linear system. Finally, these solutions are determined by developing a new analytical method. This method combines elements from approaches applied for piecewise linear systems with constant coefficients as well as classical perturbation techniques applied for systems with time varying coefficients. The validity and accuracy of the approach is verified by numerical results. In addition, response diagrams are presented, illustrating the effect of the constant load and the damping on the gear-pair response.
Dynamic Vibration Absorber for a Ropeway Carrier
Authors: Matsuhisa Hiroshi , Nishihara Osamu
Published: February 2021

Ropeways such as gondola lifts have attracted increasing interest as a means of transportation in cities. However, swing of ropeway carriers is easily caused by wind, and usually a ropeway cannot operate if the wind velocity exceeds about 15m/s. The study of how to reduce the wind-induced swing of ropeway carriers has attracted many researchers. It had been said that it was impossible to reduce the vibration of pendulum type structures such as ropeway carriers by a dynamic absorber. But in 1993, Matsuhisa showed that the swing of carrier can be reduced by a dynamic absorber if it is located far above or below from the center of oscillation. Based on this finding, a dynamic absorber composed of a moving mass on an arc-shaped track was designed for practical use, and it was installed in chairlift-type carriers and gondola type carriers in snow skiing sites in Japan in 1995 for the first time in the world. It has been shown that a dynamic absorber with the weight of one tenth of the carrier can reduce the swing to half. The liquid dynamic absorber was also investigated. It has the same damping effect as the conventional solid absorber. It is easy to adjust the natural frequency and the damping ratio, and the structure is simple. Therefore, it will be applied for not only ropeway carriers but also ships and rope suspended bridge and others.