bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Behavior of Aircraft Wings Modeled as Doubly-Tapered Composite Thin-Walled Beams
Authors: Na Sungsoo , Librescu Liviu 
Published: December 2021

Abstract
A study of the dynamical behavior of aircraft wings modeled as doubly-tapered thin-walled beams, made from advanced anisotropic composite materials, and incorporating a number of non-classical effects such as transverse shear, and warping inhibition is presented.
The supplied numerical results illustrate the effects played by the taper ratio, anisotropy of constituent materials, transverse shear flexibility, and warping inhibition on free vibration and dynamic response to time-dependent external excitations. Although considered for aircraft wings, this analysis and results can be also applied to a large number of structures such as helicopter blades, robotic manipulator arms, space booms, tall cantilever chimneys, etc.
Assessing Creativity in Engineers
Authors: Larson Michael C. , Thomas Benjamin H. , Leviness Peter O. 
Published: December 2021

Abstract
This study investigates how well certain popular psychological written tests aimed at assessing creativity relate to the performance of undergraduate mechanical engineering students engaged in a design competition. There is a growing awareness of the need to stimulate creativity in students. A valid standardized test would be useful for educators to develop curricular components aimed at bolstering student creativity and to measure the success of efforts to instill creativity. The Myers-Briggs Type Indicator1, the Torrance Tests of Creative Thinking2, and the Revised Minnesota Paper Form Board Test3 were administered to students enrolled in a sophomore-level engineering design course at Tulane University. In addition, a modified Ypma’s Biographical Questionnaire4 was used to gather personal data from each student. The design competition served as a basis for evaluating the individual’s applied creativity in an open-ended, yet constrained, engineering design activity.
For the particular group tested, the three tests were poor indicators of the engineering creativity embodied in the students’ designs. It may be that the attributes which contribute to creativity in an engineering exercise differ from those which contribute to creativity in a more general sense, for example in art and literature, and which are measured by the tests. Responses to the biographical questionnaire suggest that, while the whole class shares a similar socioeconomic background, the students judged to be creative in the design activity possess certain qualities which distinguish them from the rest of the group. Noteworthy in this regard is the difference in the self-perception of creative ability — the creative students see themselves as being less creative than the other students see themselves. It may be worthwhile to follow up this small-sample investigation and undertake a larger study using the biographical questionnaire to collect information about personal experiences (presumably something that can be addressed in an engineering curriculum). This present study, although limited in scope, indicates that great care should be taken before the engineering community embraces a diagnostic test for creative potential.
Teaching Tools for Teachers: An Engineering Design Project to Enhance Science and Mathematics Education for Middle/High School Students
Authors: Nagchaudhuri Abhijit , Conway Harold M. 
Published: December 2021

Abstract
With the approach of the new millennium and the emergence of the global market, significant restructuring of university education in general, and science and engineering education in particular, is taking place with the objective of preparing the students for the new social and economic order.
The paradigm shift and emerging trends in engineering education demand a holistic integration of “soft” and “technical” skills. There is also an emphasis on “educational outcomes” as evidenced by student design projects and other outcome evaluation criteria. “Service-Learning”, an approach that endeavors to integrate “community service” and “student learning” has found wide acceptance in the Humanities and Social Sciences. Implemented in a novel and creative fashion, it may well provide an effective pedagogical tool consistent with the new paradigm of engineering education.
The design project described in this paper integrates both “Service-Learning” and “Design Project” requirements in the first course in “Engineering Mechanics” offered at the University of Maryland Eastern Shore (UMES), Engineering Program. One of the desired “outcomes” of the course is that the student not only understands the theory as discussed in class but also learns to apply the knowledge to develop and design engineering products useful for the society. The project demonstrates the development of a device that visually reinforces concepts related to Newton’s laws of motion and mechanical advantage in simple machines (lever arms, pulley systems, and springs), in consultation with a science and mathematics teacher in a local high school. In the future, the device will be utilized in the school and benefit education efforts not only at the high school level but also in the elementary and middle schools. It is anticipated that it will also help introduce the field of Engineering to school students.
During the implementation of the project, other learning outcomes were accomplished in concert with the demonstration of application of engineering mechanics and providing service to the community. The student has reflected that the project has helped him in realizing the “role” of the customer in engineering design, developing a clear perception of constraints in space, time and budget in implementing projects, and improving communication skills. It has also given him a better appreciation of the role of engineering in society and helped his inner growth as an individual and a citizen.
Reverse Engineering of Free-Form Surfaces: Data Reduction When Using an On-Line Contact Probe
Authors: Wong K. , Krishnan K. K. , Bahr B. , Chowdhury P. P. 
Published: December 2021

Abstract
When reverse engineering free-form surfaces a perennial question is the limit on the number of points to be measured and the size of the grid in which the points are measured. The size of the grid can be determined only after an analysis of the surface is performed. However, the data required for analysis is not available. Hence, a continuous scanning technique or scanning at very close intervals is necessary. When using continuous scanning techniques for reverse engineering free-form surfaces a large number of points are generated. The transfer of these points into a CAD system to generate a NURBS surface requires a large database. Fitting a surface through a limited set of points and performing a geometric analysis of the surface to determine the complexity of the surface can reduce the excessive number of points. The complexity of the surface will be determined by using such parameters as radius of curvature. Additional points can be measured at necessary location based on the analysis. This research describes the development of an integrated reverse engineering system that will measure a free-form surface using a scanning contact probe and determine the location points on the surface to be measured. The developed system reduces the number of data points that are measured and stored. The software has been developed using ACIS and C++.
Dynamics of Metalcutting
Authors: Isakov Edmund 
Published: December 2021

Abstract
A practical engineering method of calculating tangential cutting force in milling is proposed. The method is based on the ultimate tensile strength of a work material, cross-sectional area of uncut chip, the number of inserts in cut, and a machinability factor of a workpiece material. Milling tests of high shear cutters with torque dynamometer were carried out at a wide range of the cutting conditions and various workpiece materials to verify the concept. Proposed method provides the accuracy of ± 15% or better for calculating tangential cutting force, torque, and power consumption in relationship with machining conditions and work material mechanical properties.
Development of a Cutting Direction and Sensor Orientation Independent Monitoring Technique for End-Milling
Authors: Roth John T. , Pandit Sudhakar M. 
Published: December 2021

Abstract
In the authors’ previous work, univariate models were fit to acceleration data to predict impending tool failure. Numerous end-milling life tests, conducted under a wide variety of cutting conditions, demonstrated that the method could consistently warn of impending failure between 6 inches (15 cm) and 8 inches (20 cm) prior to the actual event. This paper presents an improved method that increases the warning time and allows the technique to function independent of the cutting direction or sensor orientation. Using multivariate autoregressive models fit to tri-axial accelerometer signals, monitoring indices are developed, verified and the results are compared with those from the univariate models. The multivariate models detected impending failure 30 inches (76 cm) prior to its occurrence, 23.5 inches (60 cm) earlier than with the univariate models. Furthermore, the multivariate models are able to monitor the condition of the tool, regardless of the cutting direction or sensor orientation.
Modeling Oscillations During Conduction Mode Laser Welding
Authors: Smith Elizabeth T. , Schultz William W. , Kannatey-Asibu Elijah 
Published: December 2021

Abstract
Thermal, optical, and acoustic signals are generated during laser welding by the many physical phenomena which govern the laser beam-material interactions involved in welding. The objective of this study is to analyze one potential source of these signals — oscillations of the molten weld pool. Weld pool oscillations are modeled as gravity-capillary waves in a partially penetrating, conduction mode weld pool. The weld pool is assumed to be stationary and cylindrical, containing inviscid, incompressible, irrotational liquid metal. Dynamic and kinematic boundary conditions are imposed at the free surface of the pool, with impenetrability providing a boundary condition at solid boundaries. Two different edge conditions are examined. First, the free surface is assumed to meet the boundary orthogonally. Second, the contact line is assumed to remain fixed during pool motion. Solution of the governing equations subject to the boundary conditions provides the natural frequencies of oscillation and mode shapes governing pool motion. Results from the analytic model agree well with preliminary experimental data. The dominant mode of oscillation can be characterized as a sloshing of material from the front to the back of the pool, occurring at approximately 700Hz for the conditions examined.
High Precision Cutting and High Speed Interrupted Cutting of Hardened Steel With PCBN Tools
Authors: Yoshida Katsuhito , Kukino Satoru , Harada Takashi , Fukaya Tomohiro , Shiraishi Junichi , Nakai Tetsuo 
Published: December 2021

Abstract
PCBN (Polycrystalline Cubic Boron Nitride) cutting tools have become very familiar in the industries for cutting hardened steel parts and the demand for PCBN tools is growing rapidly. One of the reasons for this is the trend of replacing grinding processes with cutting. Although the trend of processing is to use more cutting, there still remains grinding in many processing fields. High precision machining and high speed interrupted machining have been such fields. In this study it has been verified that a novel cutting method can be applied to high precision machining with the smoothness of Rz 0.8 μm and that a new PCBN has sufficient reliability against tool failure in high speed (&lt; 250m/min) interrupted cutting. Thus cutting has become applicable to those machining and the trend of replacement of grinding with cutting will be enhanced. Those new technologies will be introduced in this report.
Modal Analysis and Modeling of a Parallel Kinematic Machine
Authors: Hardage David S. , Wiens Gloria J. 
Published: December 2021

Abstract
This paper presents the results of a mini-modal survey on the Hexel Tornado 2000, a parallel kinematic machine tool located at Sandia National Laboratories, and discusses the finite element model that is used to simulate the structural dynamics of this machine. Preliminary data suggests a dependency of resonant frequency and stiffness characteristics on machine configuration.
Study of Edge Effects in Laser Bending
Authors: Bao Jiangcheng , Yao Y. Lawrence 
Published: December 2021

Abstract
Laser forming has not been widely used due to limited understanding of its mechanism and immaturity of processing technology. In the study of single axis laser bending of plates, edge effects affect accuracy of the bending. Experimental and numerical studies are carried out to study the mechanism of the edge effects. Temperature dependency of material properties and strain-rate dependency of yield stress are considered in numerical simulation. Numerical results match well with experimental results. Patterns of edge effects are examined in terms of bending angle variation and curved bending edge under different conditions. A more complete explanation for the mechanism of the edge effects is given.
Frequency Domain Analysis of Vibrations in Liquid-Filled Piping Systems
Authors: Jiao Zongxia , Hua Qing , Yu Kai 
Published: December 2021

Abstract
In the analysis of liquid-filled piping systems there are Poisson-coupled axial stress waves in the pipe and liquid column, which are caused by the dilation of the pipe. In some conditions the influence of viscous friction that is usually frequency-dependent should not be omitted, which in fact is another kind of coupled form. It directly influences the amplitude of vibration of piping systems to some degree. The larger the viscosity of the liquid is, the greater the influence will be. Budny (1991) included the viscous friction influence in time domain analysis of fluid-structure interaction, but did not give frequency domain analysis. Lesmez (1990) gave the model analysis liquid-filled piping systems without considering friction. If the friction is not included in frequency domain analysis, the vibration amplitude will be greater than that when friction is included, especially at harmony points, cause large errors in the simulation of fluid pipe network analysis, although it may have little influence on the frequency of harmony points. The present paper will give detail solutions to the transfer matrix that represents the motion of single pipe section, which is the basis of complex fluid-structure interaction analysis. Combined with point matrices that describe specified boundary conditions, overall transfer matrix for a piping system can be assembled. Corresponding state vectors can then be evaluated to predict the piping and liquid motion. At last, a twice-coordinate transformation method is adopted in joint coupling. Consequently, the vibration analysis of spatial liquid-filled piping systems can be carried out. It is proved to be succinct, valid and versatile. This method can be extended to the simulation of the curved spatial pipeline systems.
A Modified Tustin Transformation for Improved Controller Performance With Application to the Electrohydraulic Actuator
Authors: Kim Dean H. , Moulton Shawn J. , Tsao Tsu-Chin 
Published: December 2021

Abstract
This paper presents a modified Tustin transformation which can be used in the design process to improve controller performance significantly by reducing control input fluctuations caused by unfavorable controller pole locations. An important application is the design of robust performance controllers, which can exhibit control input fluctuations due to the rigidity of the known optimal solutions. This modified Tustin transformation utilizes a scaling factor to map the stability region of the continuous domain to a region in the discrete domain which excludes the undesirable points near z = −1. In comparison to the standard Tustin transformation, this scaling factor affects the mapping of only the points in the continuous domain corresponding to high frequencies. Hence, a critical feature of this modified transformation is that it preserves the mapping from the origin in the continuous domain to point z = 1 in the discrete domain, because this pole location corresponds to integral control. This modified Tustin transformation is applied to the robust performance controller designs for the electrohydraulic actuator. The objective is to perform a number of controller designs with different scaling factors and then determine the design which provides the best compromise between improved controller performance and achieved system performance. The simulation results and experimental data demonstrate that a scaling factor equal to 1.2 improves controller performance and maintains system performance when compared to the controller design using the standard Tustin transformation. Specifically, the control input signal energy is reduced by 53%, the system overshoot is reduced by 47%, and the settling time is reduced by 42%.
Adaptive Robust Precision Motion Control of Single-Rod Hydraulic Actuators With Time-Varying Unknown Inertia: A Case Study
Authors: Bu Fanping , Yao Bin 
Published: December 2021

Abstract
This paper studies the precision motion control of single-rod hydraulic actuators with time-varying unknown inertia loads. The swing motion control of a robot arm driven by a single-rod hydraulic actuator (a scaled down version of industrial backhoe loader arm) is used as a case study. During the swing motion, the effective mass acting on the hydraulic actuator varies greatly with the swing angle and thus time-varying. Furthermore, due to the change of the load of the robot arm in operations, the effective mass is also unknown. A discontinuous projection based adaptive robust controller is constructed to take into account this strong dependence of the effective mass on the fast changing swing angle and the unknown payload of the arm. The resulting ARC controller is able to take into account not only the effect of parametric uncertainties coming from the payload and various hydraulic parameters but also the effect of uncertain nonlinearities such as uncompensated friction forces and external disturbances. The ARC controller guarantees a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties. In addition, the zero output tracking error dynamics for tracking a large class of time-varying trajectories is shown to be globally uniformly asymptotically stable. Comparative experimental results are presented to show the effectiveness and the high performance nature of the proposed control algorithm.
Modeling and Optimization of Fixture for Handling Compliant Sheet Metal Parts
Authors: Ceglarek D. , Li H. F. , Tang Y. 
Published: December 2021

Abstract
Material handling of compliant parts is one of the most critical and underresearched problems in the sheet metal stamping industry. The fundamental shortcoming of currently studied material handling systems for sheet metal stamping is the lack of analysis of its impact on part dimensional quality and production throughput.
This paper addresses this problem by development of a generic methodology for modeling and optimization of part holding end-effector fixture layout in order to minimize part dimensional deformation during handling operations. The methodology extends the design of “N-2-1” fixturing layout by adding part movability conditions. It considers part CAD model, handling direction and motion kinematic parameters to determine the best end effector layout. This methodology is realized by integrating FEM part and loading modeling with the optimization algorithm. It can be implemented into the design stage of a stamping line so that the trial and error process, which is current industrial practice, can be greatly shortened and the production throughput increased. Experimental results verify the proposed part holding end-effector layout methodology.
A Steady-State Model for the High-Pressure Side of Unitary Air-Conditioners
Authors: Petit Pascale J. , Meyer Josua P. 
Published: December 2021

Abstract
A steady-state model was developed to predict the performance of the high-pressure side of vapour-compression air-conditioning systems. The model consists of two segments; the compressor model and condenser model. The compressor model consists of a single empirical equation, for reciprocating compressors, operating with R-22, and having a cooling capacity from 2.6 to 3.5 kW. An important advantage of the approach is that the compressor performance indexes are based on operating conditions. The condenser model displays an exact method to determine physical dimensions of heat exchangers, and a simple, accurate manner to calculate the heat transfer variables. The correctness of the condensing temperature is obtained by an iterative procedure, using terms from both the compressor and condenser studies. The feasibility of the proposed model is demonstrated via a comparison with experimental data and a simulation study. Results indicate a good correlation between the mathematical model and its counterparts.
Extension of the Definition of Entropy and Temperature for Thermodynamic Systems Defined by More Than Two Independent Variables
Authors: Kouremenos Demetrius A. 
Published: December 2021

Abstract
In a previous paper [1] by the same author, it has been shown how to define the entropy and temperature of a thermodynamic system by using a system of two differential equation. This way of definition concerned thermodynamic system that can be described by only two independent variables such as volume v and internal energy u. By the present work this definition is shown to be valid even for more complicated systems described by more than two independent variables such as the ones that include chemical reactions, burning processes or any other. From the mathematical point of view, the extension of definition of entropy and temperature to thermodynamic systems with more than two independent variables is equivalent to finding an integrating factor for Pffafian forms having more than two independent variables. This mathematical problem is not generally solved, if such a solution is possible at all. But for the case concerned here, the special differential forms defining the entropy and temperature can deliver solutions of the problem, as it is shown in the paper. In this way, after having obtained these special solutions there is no need to prove the mathematical existence of solutions for this system of differential forms.