bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decoupling Methods in Flexible Multibody Dynamics
Authors: Hwang Yunn-Lin 
Published: March 2021

Abstract
The inertia projection schemes used in the existing recursive methods for the dynamic analysis of flexible multibody systems lead to dense coefficient matrices in the acceleration equations. Consequently, there is a strong dynamic coupling between the joint and modal coordinates. When the number of modal degrees of freedom increases, the size of the coefficient matrix in the acceleration equations becomes large and consequently the use of these recursive methods for solving the joint and modal accelerations becomes less efficient. This investigation discusses the problems associated with the inertia projection schemes used in the existing recursive methods, and it is shown that decoupling the joint and modal accelerations using these methods requires the factorization of nonlinear matrices whose dimensions depend on the number of modal degrees of freedom of the system. An amalgamated formulation that can be used to decouple the modal and joint accelerations is proposed. In this amalgamated formulation, the relationships between the Cartesian, modal and joint variables and the generalized Newton-Euler equations are utilized to develop systems of loosely coupled equations that have sparse matrix structure. Using the structure of the inertia matrix of the deformable body and the fact that joint reaction forces associated with modal coordinates do not represent independent variables, a reduced system of equations whoSe dimension is independent of the number of modal degrees of freedom is obtained. This system can be solved for the joint accelerations as well as the joint reaction forces. The use of the procedure developed in this paper can be used for open-loop and closed-loop mechanical systems.
Trajectory Planning for a Mobile Robot in an Unknown Environment by Fuzzy Based Method
Authors: Beaufrere Bertrand , Zeghloul Said 
Published: March 2021

Abstract
The objective of this paper is to present a simple local navigation method for a mobile robot in an unknown environment. A part of the simulation aspect is presented. It concerns the model environment technic and the motion control system. The local free environment of the robot is perceived by 12 ultrasonic sensors. We present a method which uses the sensor’s data to determine free channel. Then, we describe our free path planning method which is based on these sensor’s information in order to reach a target point. The described method uses a Fuzzy reasoning Some simulation results are included in the last section.
An Efficient Algorithm for CSG Rendering
Authors: Chao Ming , Zhao Wei 
Published: March 2021

Abstract
CAD modelling encompasses many problems, from realistic rendering to process planning. This paper presents a new surface scanning algorithm for five typical primitives (block, sphere, cylinder, cone and torus). The algorithm is efficient and robust. The speed of scanning mainly depends on the 2D screen area on which the primitive surface casts, while back-face is eliminated before scanning. Since primitive surfaces are scanned from their algebraic definition, a compact database can be maintained. A new approach of utilising space-coherence to minimise the process time for point-membership classification is described.
A Mechanical Design Framework Based on Object-Oriented Approach
Authors: Jeong Taesik , Kicher Thomas P. , Zab Ronald J. 
Published: March 2021

Abstract
An object-oriented programming (OOP) technique is investigated in order to develop the framework for mechanical design automation systems. A task-oriented decomposition approach is applied to conceptualize the task-object (or task-performing-object) in which common behavior and communication protocols are encapsulated [1]. Each task in the entire design process, either controlling design strategies or performing design methods, is made into an object. The design method objects are implemented using Artificial Intelligence (AI) paradigms, such as artificial neural networks and expert systems.
This report explains how OOP is integrated to develop a mechanical design framework (MDF). A single reduction gear box design process was used to identify some of the general tasks involved in mechanical design process. From this process the guidelines for developing task-objects for future systems are formed. Full details of these guidelines and an implementation example in Smalltalk on a PC are available in [7].
The Effect of Transducer Response Rate on Thermal Radiation Data
Authors: Loucks Richard B. 
Published: March 2021

Abstract
The Thermal Radiation Source (TRS) at ARL is used as a research tool to develop a reliable TRS unit for integration with the 2.44 m probative tube. Part of this study includes measuring the rise and fall times as well as the extent of flux variation of the TRS events. The Garden type gage is the primary transducer used to measure the flux output. This gage consists of a constantan diaphragm welded to a copper wire and body. This creates two thermocouple junctions. The electrical output of the gage is linearly related to the incident thermal radiation on the face of the diaphragm.
A concern is about the response rate of these gages. The typical gage used in TRS work has a response rate of one time constant within 50 ms. In the past, the transient output of the TRS was considered slow. A faster acting gage was not necessary. To test this theory, a mathematical correction formula was applied to existing TRS data. The correction formulation was to demonstrate the actual incident radiation on the gage face by assuming a response rate. The data was processed using the correction formula. The results of the correction processing yielded a higher rise and fall time, as expected, but demonstrated a much higher flux variation during a TRS event. The overall fluence remained the same.
To verify the correction formula is accurate, a special gage was constructed. It has a response rate of 6 ms to the first time constant. An experiment was conducted by placing the special gage next to a regular gage. The results show the faster acting gage produces a signal that matches the corrected signal of the slower gage, with one exception. The overall fluence increased.
The most profound effect of this gage is realized when attempting to improve the performance of a TRS system. By realizing the capabilities of the gages, a more accurate determination of the thermal output of future TRS systems can be assessed. This will have direct impact on future Nuclear Survivability criterion by realizing the true capabilities of TRS systems.
An Integrated Modeling and Analysis Methodology for Configuration Design of Disk Drive Actuators
Authors: Strzepa M. C. , Grosse Ian R. 
Published: March 2021

Abstract
In this research we have developed a methodology for integrating design and finite element analysis, with special emphasis on design. System performance goals are translated into local performance goals based on generic physical principles. A complete search of the design domain may not be possible due to its size and not realistic due to time-to-market pressures. Furthermore, the complexity and non-linearity of the design domain prohibit a qualitative comparison of design configurations without design instantiation and evaluation. The use of a “pruning” process of the configuration design space is highly desirable since it provides the means of selecting a single candidate configuration having the greatest potential for success. Therefore, an approach is used in which design configurations are parameterized from a product knowledge base through the use of a library of design templates. The design process involves an enumeration of candidate design templates and domain-specific automated procedures for finite element mesh generation. Through exploitation of domain-dependent knowledge, FEA solution accuracy requirements are defined. Quantitative behavior is then inferred from numerical results. Examples involving the design of a computer disk drive actuator are presented which convey these concepts.
An Investigation Into Mathematical Models of Optimal Tolerancing Supporting Concurrent Engineering
Authors: Zhang Genbao , Porchet Michel 
Published: March 2021

Abstract
This paper presents a new tolerance design theory — simultaneous tolerancing which works in the concurrent engineering context. After the necessity to develop a simultaneous tolerancing theory is stated, by showing the shortcomings of conventional tolerancing technique, the concept of simultaneous tolerancing is given, and its elements are briefly presented. Then we focus our attention on the development of a general mathematical model of optimal tolerancing supporting concurrent engineering. Two commonly used models, worst-case and statistical, are discussed in detail. Next, a method of “interim tolerances”, which help to determine an appropriate machining process without using functional tolerances, is proposed.
The simultaneous tolerancing theory presented in this paper permits of determining directly optimal machining tolerances in product design, reducing the manufacturing cost and improving the quality of products.
Monitoring Systems Using PVM
Authors: Li Qiang , Yip T. Gary 
Published: March 2021

Abstract
This paper presents a cost-effective implementation of a sensor monitoring system based on a network of workstations and microprocessor building blocks. The PVM (Parallel Virtual Machine) system is used as the software platform running the workstations. Owing to PVM, the burden of network programming is eliminated. The control software running on multiple workstations can be implemented in a way similar to that of a single workstation. The interfaces to users and to databases can be easily implemented.
Simulation and Shape Synthesis of Kinematic Pairs via Small-Scale Interference Detection: Advanced Examples Demonstrating Shape Optimization and Non-Fixed Axis Members
Authors: Gupta Rakesh , Jakiela Mark J. 
Published: March 2021

Abstract
A method to simulate the interactions between kinematic pairs (meshing gears, cams and followers, Geneva mechanisms, etc.) has been described in an earlier paper (Gupta and Jakiela, 1992a). This second paper, through several examples, demonstrates how our representations and algorithms for kinematic simulation and shape synthesis facilitate subsequent reasoning for design tasks. Included are examples of a complex industrially relevant simulation, shape optimization motivated by kinematic behavior, and extensions of the approach for non-fixed-axis members.
The Importance of Free-Hand Sketching in Conceptual Design: Automatic Sketch Input
Authors: Jenkins D. L. , Martin R. R. 
Published: March 2021

Abstract
Free-hand drawing (sketching) is important in the conceptual design stage. Current CAD tools are not well suited to sketching. This statement is supported by an examination of free-hand drawing, a brief overview of some commercially available drawing packages and a discussion of other authors’ work in this area. Finally we present objectives for automatic sketch input and their partial realisation in our drawing system called Easel.
Extraction and Reuse of Design Information
Authors: Jamalabad Vikram R. , Langrana Noshir A. 
Published: March 2021

Abstract
An iterative design procedure constitutes a significant part in many design process with no closed form solutions. Of importance to this procedure is the acceleration of this cycle to reduce turnaround time. The analysis packages concerned have a large execution time and defined sets of input and output parameters. The number of these parameters is large and information about the design space is incomplete. The aim is to minimize the number of analysis calls during the design procedure. We have developed a system (Learning Shell for Iterative Design, or, L’SID) to enable a current iterative design system to extract and use information from an analysis package during the iterative design process. L’SID is a domain independent system written in lisp that has been demonstrated to operate on the said class of analysis modules. The system compiles domain information in a domain independent data structure. The modularity of the system enables us to change analysis packages, search methods, iterative processes and comparison functions. Results encourage us to believe that such systems will be helpful in maintaining, averring or refuting domain specific information for routine design systems.
Recursive Annealing: A Computational Model for Machine Design
Authors: Schmidt Linda C. , Cagan Jonathan 
Published: March 2021

Abstract
A recursive model of conceptual design occurring along an abstraction continuum is introduced. An algorithm based upon recursive simulated annealing is proposed for a computational implementation of the model. The mapping from function to form is accomplished using an abstraction grammar, a set of compatible string grammars for representing the function and form nature of machine components at various levels of abstraction. The promise of a recursive approach to machine design is demonstrated.
On the Axiomatic Foundation of Design
Authors: Dimarogonas Andrew D. 
Published: March 2021

Abstract
Mechanical design methodology has its origins in the writings of ancient Greek and Alexandrine authors between 300 BC and 100 AD when also the first aesthetic theory was proposed. German authors of the middle of 19th Century have introduced the foundation for Mechanical Design on basic Design Principles, modernized the machine element methodology and introduced the parallel development of the function with the form. F. Redtenbacher introduced a set of design principles. Reuleaux (1852) introduced two fundamental Design Principles (Ground Rules), re-introduced recently in axiomatic form by Suh et al. The paper discusses the merits of establishing Design Principles or Design Axioms as the fundamental Rules of design and the implications of these Rules on the design and manufacturing methodology. The relation of the Design Rules with the principles of the total quality engineering in the Taguchi sense is also investigated.
Non-Linear Normal Modes, Invariance, and Modal Dynamics Approximations of Non-Linear Systems
Authors: Boivin Nicolas , Pierre Christophe , Shaw Steven W. 
Published: March 2021

Abstract
Non-linear systems are here tackled in a manner directly inherited from linear ones, i.e., by denning proper normal modes of motion. These are defined in terms of invariant manifolds in the system’s phase space, on which the uncoupled system dynamics can be studied. Two different methodologies which were previously developed to derive the non-linear normal modes of continuous systems — one based on a purely continuous approach, and one based on a discretized approach where the theory developed for discrete systems can be applied — are simultaneously applied to the same study case — an Euler-Bernoulli beam constrained by a non-linear spring —, and compared as regards accuracy and reliability, resulting in the abandonment of the continuous approach for lack of reliability. Numerical simulations of purely non-linear modal motions are performed using these approaches, and compared to simulations of equations obtained by a classical projection onto the linear modes. The invariance properties of the nonlinear normal modes are demonstrated, and it is also found that, for a purely non-linear modal motion, the invariant manifold approach achieves the same accuracy as that obtained using several linear normal modes, but with significantly reduced computational cost. This is mainly due to the possibility of obtaining high-order accuracy in the dynamics by solving only one non-linear ordinary differentia] equation.
Steady State Solutions to a Forced Nonlinear Oscillator: A Comparison of Results Using a Generalized Harmonic Balance Method and by Numerical Integrations
Authors: Noble Ben , Wu Julian J. 
Published: March 2021

Abstract
Steady state solutions for nonlinear dynamic problems are interesting because (1) the long time behaviors of many problems are of practical concern, and, (2) these behaviors are often difficult to predict. This paper first presents a brief description of a generalized harmonic balance method (GHB) for steady state solutions to nonlinear problems via a nonlinear oscillator problem with a quadratic nonlinearity. Using this approach, steady state solutions are obtained for problems with several parameters: damping, nonlinearity and frequency (subharmonic, superharmonic and primary resonance). These results, plotted in time evolution curves and phase diagrams are compared with those obtained by numerically integrating the original differential equations. The effect of initial conditions on long time solutions is discussed. This investigation indicates that (1) the GHB steady state is an excellent approximate solution to that of the original equation if such a solution is numerically stable, and (2) the GHB steady state simply indicates a region of instability when the numerical solution to the original equation, using a point in that region as the initial point, is unstable.
A Preliminary Study of Self-Loosening in Bolted Connections
Authors: Zadoks Rick I. , Yu Xiong 
Published: March 2021

Abstract
Bolted connections are the most common method used to fasten together two or more structural elements. After fatigue, self-loosening is the most frequent cause of failure of dynamically loaded bolted connections. Bolted connections experience self-loosening due to relative motion between the thread flanks and between other contact surfaces of the clamped or clamping elements. If the relative motions are eliminated, then no dynamic self-loosening can occur. It is found that the relative transverse motion d at a bolted connection is directly related to the preload Q and the transverse force F applied to the bolt. As a basis for the study of bolt self-loosening, a model of thread slipping is established, and relationships between Q, F and d are theoretically derived. It is found that the stiffness of the bolt threads is approximately parabolic. Due to this nonlinear relationship between Q and d, it is found that the relationship between F and d is also nonlinear. For a given set of geometrical and material parameters, the critical transverse force Fcr (i.e., the minimum force needed to make the threads slip) can be predicted. Experiments are run and though the results are obscured by the presence of other effects including sliding friction between the clamped parts and bending of the bolt body, it seems that qualitative agreement exists between the theoretical model and a physical system. The results presented in this work serve as the preliminaries to the development of a model of the dynamic self-loosening of bolted connections and, as such, offer an insight into the mechanisms that lead to self-loosening. Additionally, these results offer clues regarding methods that could be used to prevent bolted connection failures.
A Successive Merging and Condensation (SMAC) Method Applied to Transient Analysis of Multi-Shaft Rotor System
Authors: Ratan Santosh , Rodriguez Jorge 
Published: March 2021

Abstract
A method for performing transient dynamic analysis of multi-shaft rotor system is proposed. The proposed methodology uses the reported Successive Merge and Condensation (SMAC) method [12] and a decoupling technique to decouple the shafts. Multi-shaft rotor systems are treated as systems of many independent single shaft rotor systems with external unknown coupling forces acting at the points of couplings. For each time step, first, the SMAC method is used to get the transient response in terms of the unknown coupling forces. This is followed by the application of the coupling constraints to calculate the coupling forces and, in turn, the response at the end of that time step. The proposed method preserves the efficiency advantages of the SMAC algorithm for single-shaft rotor system. Numerical examples to validate and illustrate the applicability of the method are given. The method is shown to be applicable to linear and non-linear coupling problems.
Resonant Vibrations in Weakly Coupled Nonlinear Structures With Cyclic Symmetry
Authors: Samaranayake S. , Bajaj Anil K. , Nwokah O. D. I. 
Published: March 2021

Abstract
Periodic structures with cyclic symmetry are often used as idealized models of physical systems including bladed-disk assemblies, large space antennas, circular saws and disks, and flexible magnetic storage media. The present work considers a simplified model of such structures and investigates the nonlinear vibratory response to periodic excitations. The model consists of n identical particles, arranged in a circular ring, interconnected by extensional springs with linear and nonlinear stiffness characteristics, and hinged to the ground individually by nonlinear torsional springs. When the linear couping stiffness is O(ε), the cyclic system consists of n weakly coupled identical nonlinear oscillators so that all the oscillators are in internal resonance. The dynamic response of this system to resonant periodic excitation is studied using the method of averaging. The amplitude equations consist of a 2n system of first order ordinary differential equations that depend on the forcing amplitude and frequency, the modal damping, and the nature of the excitation. These equations are analyzed using local bifurcation theory, and the effects of coupling strength to nonlinearity parameter on the steady-state responses are determined. It is found that when only one particle is excited, the response for very weak coupling essentially remains localized. For larger coupling strength, both localized and extended responses are found over different excitation frequency intervals.
The Use of a Simplified Model for the Nonlinear Dynamic Analysis of Fixed Offshore Structures
Authors: Souza Marco A. , Pinto Osvaldo C. 
Published: March 2021

Abstract
A simplified model is used in the nonlinear dynamic analysis of fixed offshore platforms. The characteristics of the model are presented and its adequacy for the study is discussed. The action of ocean waves on the model is obtained using typical waves of the Brazilian coast. The nonlinear equation of motion is obtained in its exact form and is expanded up to the cubic term. A comparison between the nonlinear analysis and the linear dynamic analysis is presented. A comparison between experimental results and those obtained with the model is also presented.
Resonant Oscillations and Stability of Asymmetric Rotors
Authors: Ganesan R. , Sankar T. S. 
Published: March 2021

Abstract
Non-stationary oscillations of an asymmetric rotor while passing through primary resonance and the associated stability behaviour are analyzed. Solutions are developed based on a Jeffcott rotor model and the equations of motion are rewritten in a form suitable for applying the method of multiple scales. The many-variable version using “slow” and “fast” lime scales is applied to obtain the uniform expansions of amplitudes of motion. Similar general expressions for amplitude and frequency modulation functions are explicitly obtained and are specialized to yield steady-state solutions. Frequency-amplitude relationships resulting from combined parametric and mass unbalance excitations, for the nonlinear vibration are derived. Stability regions in the parameter space are obtained for a stable solution in terms of the perturbed steady-state solutions of the governing equations of motion. Also, trivial solutions are examined for stability. The sensitivity of vibration amplitudes to various rotor-dynamic system parameters is illustrated through a numerical study.