bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Control of a Wheelchair With a Continuously Variable Transmission (CVT)
Authors: Wada Masayoshi , Asada Haruhiko H. 
Published: January 2022

Abstract
A novel vehicle design for holonomic omnidirectional wheelchairs is presented in this paper. The new design allows the vehicle to change the shape of its footprint as well as to continuously vary the gear ratio of the drive mechanism. The variable footprint mechanism consists of a pair of beams intersecting at a pivotal point in the middle. Two pairs of ball wheels at the diagonal positions of the vehicle chassis are mounted, respectively, on the two beams. The angle between the two beams varies actively so that the ratio of the wheel base to the tread may change. Four independent servomotors driving the four ball wheels allow the vehicle to move in an arbitrary direction from an arbitrary configuration as well as to change the angle between the two beams and thereby change the footprint configuration. The objective of controlling the beam angle is threefold. One is to augment the static stability of the vehicle by varying the footprint so that the mass centroid of the vehicle may be kept within the footprint at all times. The second is to reduce the width of the vehicle when going through a narrow doorway. The third is to apparently change the transmission ratio relating the vehicle speed to individual actuator speeds. Required vehicle tasks are coordinated by the hierarchical control architecture. First the concept of the varying footprint mechanism is described briefly, then three control algorithms for varying the footprint are presented followed by the hierarchical control architecture for coordinating the different tasks. A proof of concept prototype wheelchair is designed, built, and tested.
A Procedure for the Synthesis of Simple Spring Realizable Spatial Stiffnesses
Authors: Huang Shuguang , Schimmels Joseph M. 
Published: January 2022

Abstract
In this paper, the synthesis of the stiffness matrices that can be realized with “simple springs” connected in parallel to a single rigid body is presented. The expression “simple spring” is used to refer to the set of elastic relations associated with passive translational springs and rotational springs.
We have previously identified the realizable sub-space of stiffnesses achieved with simple springs and provided a procedure to synthesize an arbitrary full-rank stiffness matrix within this realizable subspace. In this paper, an optimization routine is used in conjunction with the synthesis procedure to obtain alternate sets of springs that better satisfy practical design considerations. The procedure presented here requires no more than 7 simple springs to realize any simple spring realizable stiffness.
An Evolutionary Algorithm for the Reduction of DOFs in Modular Reconfigurable Robots
Authors: Chen I-Ming , Yang Guilin 
Published: January 2022

Abstract
The Reduced Degree-of-freedom (RDOF) concept is introduced in optimizing the modular reconfigurable robot configurations for specific task requirement. With fewer modules and degrees of freedom (DOFs), a modular robot would have a simple configuration, high loading capacity, and low power consumption rate, so that it can perform the task effectively. In this article, we formulate RDOF problem as a design optimization problem. A weighted sum of the number and types of modules is chosen as the objective function. Several task-related kinematic performance measures are considered as design constraints. Based on the problem specific coding scheme, the evolutionary algorithm (EA) approach is employed to search the optimal solutions. A virtual module concept is also introduced in the coding scheme to guarantee the operation of EA. The effectiveness of this approach is demonstrated by an example.
Fuzzy Basis Function Networks of Hierarchical Structure for Modeling Manufacturing Processes
Authors: Lee Cheol W. , Shin Yung C. 
Published: January 2022

Abstract
A framework for modeling complex manufacturing processes using fuzzy neural networks is presented with a novel training algorithm. In this study, fuzzy basis function networks (FBFN) which are similar in structure to radial basis function networks are adopted. A hierarchical structure which consists of FBFNs is proposed to construct comprehensive models of the complex processes. The modeling scheme provides valuable advantages over the conventional approaches. A new adaptive least-squares (ALS) algorithm, based on the least-squares method and genetic algorithm (GA), is proposed for autonomous learning and construction of FBFNs. It adds significant fuzzy basis functions (FBF) at each iteration depending on error reduction measures while searching for the best nonlinear parameters of the networks using GA. The ALS algorithm realizes a hybrid structure-parameter learning without any human intervention. Simulation studies with grinding processes are shown to demonstrate that the proposed modeling framework with the training algorithm is a promising approach to modeling complex manufacturing processes.
Application of Intelligent Monitoring and Control in Automated Industrial Processes
Authors: de Silva Clarence W. 
Published: January 2022

Abstract
This paper will consider an intelligent supervisory control system for industrial processes. Evaluation of the performance of the process and assessment of the quality of the product are two important responsibilities of this control system. A suitable structure for the control system will be presented and some design issues will be addressed using, as illustrative examples, several practical systems which we have developed in the Industrial Automation Laboratory.
A Model for Controlled Planning of Object Manipulation Using Multiple Agents: An Overview
Authors: Payandeh Shahram 
Published: January 2022

Abstract
In implementation of intelligent mechanisms such as dexterous mechanical hands, reconfigurable fixtures or part feeders, it is always required to plan to manipulate object in order to gain its proper configuration within the work-space of the manipulating agents. Most of the proposed planners for coordinated control have been based on ad-hoc approaches using search strategies embedded within various search trees. What has been lacking in these algorithms is a formal framework for analysis, synthesis and evaluation of their performances. This paper presents an overview of application of such possible controlled planner architecture for manipulating objects using multiple agents. The controller is based on discrete-event control theory. The paper extends the application of such theory to the case of multiple agents manipulating a common object. Here for example, a set of events for lifting and rotating an object is described as labeled alphabets. Then it is shown how the manipulation of object can be described as finite-state automaton. The set of uncontrollable events is constructed. The supervisor (planner) can then be constructed by first defining the details of its legal behaviors.
Evaluation of Service-Induced Residual Stresses in Railroad Commuter Car Wheels
Authors: Gordon Jeff , Jones Jerrel A. , Perlman A. Benjamin 
Published: January 2022

Abstract
Analyses of the effects of service conditions on the distribution of residual stresses in railroad commuter car wheels are presented. Novel software has been applied to estimate the effects of service conditions on the as-manufactured state of these wheels. Contact loads resulting from wheel and rail interaction and thermal loads from on-tread braking are considered. Results indicate that contact stresses acting alone result in increased net rim hoop compression. However, thermal stresses due to frictional heating reverse the as-manufactured residual compressive state. In particular, high-performance stop braking may result in large net hoop tension in the rim. When contact and thermal loads interact, the effects of braking dominate the process. The presence of tensile residual hoop stress at the wheel tread has been shown to favor the formation and growth of fatigue cracks, threatening the safety of train operations. The paper provides a description of the analytical methodology and results of its application to a representative class of commuter service. Comparisons of the predicted depth of rim stress reversal with the thermal cracking observed in the wheels of this fleet provides confidence in the ability of the technique to assess the likelihood of thermal crack development in other types of commuter operations and in railroad freight service.
Application of Impedance Methods for Predicting Vibrations of a Locomotive Cab
Authors: Ahmadian Mehdi , Dhruna Chetran J. 
Published: January 2022

Abstract
This study evaluates the vibration isolation effect of various mounting systems in a heavy freight locomotive cab, and provides an analytical method for the prediction of structural vibration. The cab is set up in a controlled laboratory environment in a manner similar to the installation on a locomotive. Field measurements are used to emulate actual vibration input to the cab structure. A 16-channel data acquisition system is used to collect vibration data at various points on and inside the cab structure. Upon establishing the baseline for laboratory vibration measurements and correlating them with field data, acceleration data was collected at discrete locations, both inside and outside of the cab. The data was used in conjunction with an analytical formulation to generate vibration approximations of the discrete locations. To validate the analytical approximations, experimental results were compared with the analytical predictions using simulated field input to the cab. The test results from the analytical model approximations proved to have a strong correlation with experimental results. Vibration approximations of locations outside the cab had a higher correlation to the experimental data than the points on the inside. Although the model did not yield exact results for several positions inside the cab, it resulted in several recommendations for future work.
Progress in Railway Mechanical Engineering: 1997–1998 Report of Survey Committee — Passenger and Commuter Rail Vehicles and Components
Authors: Hesser Kenneth R. 
Published: January 2022

Abstract
This annual ASME committee report covers major worldwide developments in rail passenger and commuter vehicle equipment. The information contained herein was obtained from responses to survey letters sent to the manufacturers of passenger rail vehicles and components, and from a review of trade and technical publications.
Durability of Ceramic Matrix Composites
Authors: Pastor Michael S. , Case Scott W. , Reifsnider Ken L. 
Published: January 2022

Abstract
Continuous fiber reinforced ceramic composites are currently being developed as potential retrofit and replacement materials for non-structural hot section components in turbine engines. These materials display many of the beneficial high temperature characteristics of monolithic ceramics while displaying material pseudo ductility resembling durable metals. At present, however, they are very expensive to produce and test. Therefor, the development of reliable analytical techniques to augment the development and testing of these materials would be very beneficial.
A damage evolution model for composite materials is presented here as well as the its specialization to a Nicalon™ reinforced SiC composite system. Application of the model to high temperature tensile fatigue and rupture life predictions are also presented. A comparison of predicted to experimental behavior is then finally made.
Plastic and Viscoplastic Effects on Residual Strength of a Titanium Matrix Composite After Thermomechanical Fatigue
Authors: Kroupa Joseph L. 
Published: January 2022

Abstract
Using a simple fiber failure criterion, the influence of plasticity and visco-plasticity on the residual strength of a unidirectional titanium matrix composite is investigated. Solely, by the redistribution of thermally induced residual stresses, the residual strength is found to reduce after thermomechanical cycling. During in-phase thermomechanical fatigue (TMF) the strains within the fibers at high temperatures and loads are retained in the composite after cooling to room temperature. The fiber stresses, initially compressive after processing, are found to be significantly different after in-phase TMF. This shift in residual stresses reduces the predicted residual strength. Elastic and bilinear plasticity models are used to show the potential errors one may expect from simple/incomplete analysis. Using two viscoplastic models, the influence of loading frequency on residual strength demonstrates the importance of complete matrix characterization. The two viscoplastic models are Bodner-Partom and GVIPS. (Generalized viscoplastic potential structure). The influence of waveform can be observed by comparing the results of TMF using triangular, sinusoidal and square waveforms. The key feature that reduces residual strength is amount of time spent at high load and temperature.
Durability of Woven Polymer Matrix Composites
Authors: Patel Sneha R. , Case Scott W. , Reifsnider Ken L. 
Published: January 2022

Abstract
The authors of this paper obtained residual strength and damage accumulation data on an unaged composite material system consisting of a graphite reinforced polymer [[0/90]2w]s five harness satin weave. Tests were conducted under ambient conditions as well as typical aircraft temperature (120°C). The data was intended to be used to develop models of damage and failure modes to predict remaining strength and life of the material as a function of material properties and environmental factors. The models are based on damage tolerance concepts where remaining strength is used as a measure of damage accumulated in the composite and failure is assumed to occur when the remaining strength equals the applied strength.
Initial mechanical properties appeared unchanged from room temperature to elevated temperature (120°C). Matrix cracking, however, was markedly lower at elevated temperature. The major fatigue damage modes observed were matrix cracking and delamination. Residual strength for specimens fatigued at room temperature was only minimally affected while a stiffness reduction of approximately 7% was seen for specimens tested at 85 and 74 percent UTS and 50 and 75% life. At room temperature, the saturation crack density as a result of fatigue was the same as the crack saturation density found from tensile failure. At elevated temperature, the strength was again unaffected but the stiffness reduction was greater at about 12%. In addition, the crack saturation density for specimens fatigued at elevated temperature was the same as the saturation crack density for specimens fatigued at room temperature.
Because no changes in remaining strength were found, the model originally considered in this study for life prediction could not be used. Further consideration will be given to using or developing a more suitable model after more data at elevated temperature and with moisture are obtained.
Behavior of Aluminum and Plastic Bumpers Under Low and High Speed Vehicle Impacts
Authors: Alavandi Bhimaraddi , Saha Nripen 
Published: January 2022

Abstract
The most efficient crashworthiness design of a vehicle is achieved by maximizing the energy absorption and minimizing the weight of its structural components. In addition, fuel economy and environmental feasibility are best achieved by reducing the vehicle weight. In this pursuit, automotive engineers have been looking for low density materials to replace the traditional steel. Aluminum and plastic materials offer an excellent opportunity towards this goal. It is well known that material behavior of aluminum and plastic is much different than steel. They are less ductile and have limited plastic flow during deformation. Thus, their failure modes are different. Also, during crash, structures exhibit material and geometric nonlinear behavior. To simulate a high or a low speed impact, one needs to have a good understanding of the material behavior. This requires the mathematical characterization of the materials under consideration. There are several material models available in commercial finite element codes such as RADIOSS, DYNA3D and PAMCRASH (normally used in crash simulation). In this paper various material laws available in RADIOSS are used and compared in the context of aluminum and plastic bumpers. Full vehicle rear impact and the low speed bumper impact cases will be examined to illustrate the differences in various material models. Also, the influence of these models on the failure mode, energy absorption characteristics, and contact interface forces will be discussed.
An Innovative Approach to Improve Energy Absorption in Polymeric Composite Tubes
Authors: Abdel-Haq Mahmoud M. , Newaz Golam M. 
Published: January 2022

Abstract
Results are discussed on the methods to improve the crushing performance and energy absorption of unidirectional polymeric circular composite tubes. The proposed methods included using external constraints to provide hoop constraints and initiator with appropriate radii. The approaches were applied to control the crushing process by controlling the major failure modes in such a way that leads to better crushing performance of polymeric composite tubes. The major failure modes of interest were the axial cracks, delamination and the major transverse cracks. The experimental results for polyester glassfiber reinforced tubes showed that it is possible to reduce significantly the initial peak load, improve the sustained load and eliminate the transverse cracks by using an external constraint. In addition, by using initiators instead of flat platens, it was possible to ensure the splaying failure mode for the crushing process.
A 3D Nonplanar Fracture Model for Life Prediction
Authors: Forth Scott C. , Keat William D. 
Published: January 2022

Abstract
A new fracture analysis tool for simulation of 3D nonplanar growth has been developed by combining a surface integral representation of an arbitrarily shaped nonplanar crack with a finite element model of the uncracked domain. The formulations are coupled through the need to satisfy boundary conditions at the interface of the two models where numerical strategies have been adopted which have effectively decoupled the meshing requirements. As a result, a surface integral model of a crack can be superimposed onto a localized region of a complicated finite element mesh, without impacting design requirements. The crack is then grown automatically through the fixed finite element mesh, using a crack mesher that can sense changing contours and interfaces. This paper focuses on the utilization of this technology to predict fatigue life of real parts.
Life Extension of an X-Ray Tube Target
Authors: Minas Constantinos , Vermilyea Mark E. 
Published: January 2022

Abstract
A methodology for the life extension of an X-Ray target was developed. X-Ray tube targets are rotating axisymmetric multi-component components used in X-Ray tubes of medical equipment. An X-Ray target is subjected to extreme cyclic thermal loading conditions based on the imaging system requirements. A very complex, time dependent stress state is present in such targets because of the combination of processing and utilization. Residual stresses are present following initial target assembly and heat treatment required to establish and maintain the high vacuum required in the X-Ray tube. In addition, cyclic stresses arise from the imaging protocols. The factors controlling these stresses include the thermal expansion coefficients of the various materials, the temperature distributions and the geometry of the components. The proposed methodology for the life extension of an X-Ray target included the development of an integrated thermal and structural axisymmetric finite element model. The combined thermal structural model was initially used to evaluate the severity of the various thermal protocols a target is subjected to. The structural analysis was carried out in the plastic regime, since typical stresses exceeded the yield stress of the materials used. Design of experiment (DOE) studies were carried out in order to evaluate the influence of geometric quantities on the resultant temperature distribution and thermal stresses. Tolerances of geometric quantities were applied to reflect manufacturing inaccuracies. An optimal design was selected for which the equivalent plastic strains were minimized. The effect of the manufacturing tolerances on the optimal solution was also examined.
On the Role of Damage Mechanics in Life Prediction of Composite Structures
Authors: Talreja Ramesh 
Published: January 2022

Abstract
Life prediction of composite structures is still heavy in empiricism. In order to reduce the burden of extensive data generation and proof testing, and to thereby reduce cost, resort must be made to predictive, physically based models. A field with this as a central objective, and with the capability to merge elements of materials science and mechanics, is damage mechanics. This paper will address how specifically damage mechanics may be able to render life prediction methodologies a scientific basis.
First, we shall discuss the essential, sequential and interactive elements of a life prediction methodology relevant to composite structures, identifying the role of damage mechanics in such a scheme. We shall then outline a philosophy (conceptual structure) of an approach to life prediction. A simple scenario will then be treated to illustrate the ideas involved.
Finally, the multiple ways by which damage mechanics can be implemented will be discussed. The limitations inherent in isolationist (pure) forms of damage mechanics will be discussed, laying bare the need for synergistic approaches. One such approach, and the progress made in achieving it, will then be described. The references cited below report related work by this author and his associates.
Nonlinear Behavior of Sandwich Panels With a Transversely Flexible Core: High-Order Theory Approach
Authors: Sokolinsky V. , Frostig Y. 
Published: January 2022

Abstract
Nonlinear behavior of sandwich panels with a transversely flexible core is presented. The panel construction is general and consists of two face sheets metallic or composite laminated symmetric, and a “soft” core made of foam or a low strength honeycomb. The study is based on a high-order nonlinear formulation that includes the influence of the transverse flexibility and shear resistance of the core on the panel behavior, so allowing for interaction between the faces through the core thickness. The solutions obtained are general and are not based on separation of the nonlinear response on the local and global modes as commonly used in the literature on sandwich structures. The governing equations along with the appropriate boundary and continuity conditions are presented and the solution approach is outlined. The formulation is of a mixed form causing the classical solution methods used in the nonlinear structural analysis to be abandoned in favor of the more general techniques. The path-following algorithm devised is based on the natural parameter as well as the arclength continuation techniques. The quasi-Newton framework with line searches is used to solve both the nonlinear equilibrium equations and the bordered equations arising in the case of applying the arclength method. The capabilities of the formulation are demonstrated for various cases including action of a concentrated load at the mid span of the panel, loading of the panel by end couples, and compression of an unsymmetric sandwich panel by longitudinal forces. It is shown that the transverse flexibility of the core is responsible for the interaction between global and local deformation modes. Comparison with linearized buckling results is presented and conclusions are drawn.