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Articles 1 - 7 of 7
Full-Text Articles in Aerospace Engineering
Decoupled Dynamics For Control And Estimation, S. N. Balakrishnan
Decoupled Dynamics For Control And Estimation, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Decoupling of the dynamical equations in polar coordinates is used to develop a control scheme for use in target-intercept problems with passive measurements. By defining a pseudo control variable in the radial coordinate, the radial dynamics is made independent of the transverse dynamics. After solving for the radial control, the transverse control is determined through solutions to a two-point boundary value problem. Numerical results from a six degree-of-freedom simulation which used the decoupled control indicate that it is better than the completely Cartesian coordinate control for most of the cases considered. Decoupled control, though, is obtained iteratively through a two-point …
Analysis Of Shear Banding In Plane Strain Compression Of A Bimetallic Thermally Softening Viscoplastic Body Containing An Elliptical Void, Z. G. Zhu, R. C. Batra
Analysis Of Shear Banding In Plane Strain Compression Of A Bimetallic Thermally Softening Viscoplastic Body Containing An Elliptical Void, Z. G. Zhu, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We study plane strain thermomechanical deformations of a prismatic viscoplastic body of square cross-section and deformed at a nominal strain-rate of 5000 s-1. The body has two thin layers placed symmetrically about the horizontal centroidal axis and an elliptical void at the center. The major axis of the void coincides with the vertical centroidal axis and also with the direction of loading. The layer material differs from that of the body in only the value of the yield stress in a quasistatic simple compression test. The yield stress for the layer material is taken to be either one-fifth or five …
Hierarchical Neurocontroller Architecture For Intelligent Robotic Manipulation, Xavier J. R. Avula, Luis C. Rabelo
Hierarchical Neurocontroller Architecture For Intelligent Robotic Manipulation, Xavier J. R. Avula, Luis C. Rabelo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A hierarchical neurocontroller architecture consisting of two artificial neural network systems for the manipulation of a robotic arm is presented. The higher-level neural system participates in the delineation of the robot arm workspace and coordinates transformation and the motion decision-making process. The lower one provides the correct sequence of control actions. The capabilities, including speed, adaptability, and computational efficiency, of the developed architecture are illustrated by an example.
Dynamic Adiabatic Shear Band Development In A Bimetallic Body Containing A Void, R. C. Batra, Z. G. Zhu
Dynamic Adiabatic Shear Band Development In A Bimetallic Body Containing A Void, R. C. Batra, Z. G. Zhu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We study the problem of the initiation and subsequent growth of a shear band in a thermally softening viscoplaslic prismatic body of square cross-section and containing two symmetrically placed thin layers of a different viscoplastic material and an elliptical void at the center. The yield stress of the material of the thin layer in a quasistatic simple compression test is taken to be either five times or one-fifth that of the matrix material. The body is deformed in plane strain compression at a nominal strain rate of 5.000 s '. These deformations are assumed to be symmetrical about the centroidal …
Petri Net Modeling Of A Flexible Assembly Station For Printed Circuit Boards, M. Zhou, Ming-Chuan Leu
Petri Net Modeling Of A Flexible Assembly Station For Printed Circuit Boards, M. Zhou, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Petri net modeling approaches are presented for a flexible workstation for automatic assembly of printed circuit boards. In order to improve the productivity of such a system, the building of mathematical models is a crucial step. Concentrating on the operational aspects, the authors construct ordinary and temporal Petri net models for the AT&T FWS-200 physical flexible workstation. Three outcomes follow from such models. First, designers can have a better understanding of concurrency, synchronization, mutual exclusion, and sequential relations involved in the system control from the graphical representations of Petri nets. Second, the performance analysis of system operations under different settings …
Impact On Laminated Composite Materials, Serge Abrate
Impact On Laminated Composite Materials, Serge Abrate
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laminated composite materials are used extensively in aerospace and other applications. With their high specific modulus, high specific strength, and the capability of being tailored for a specific application, these materials offer definite advantages compared to more traditional materials. However, their behavior under impact is a concern, since impacts do occur during manufacture, normal operations, or maintenance. The situation is critical for impacts which induce significant internal damage, undetectable by visual inspection, that cause large drops in the strength and stability of the structure. Impact dynamics, including the motion of both the impactor and the target and the force developed …
Matrix Cracking In Laminated Composites: A Review, Serge Abrate
Matrix Cracking In Laminated Composites: A Review, Serge Abrate
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This article presents an overview of the problem of matrix cracking in laminated composite materials. The parameters governing the onset and accumulation of internal damage under several types of loadings are reviewed. The analysis of laminates with matrix cracks can be performed using a shear-lag model, variational, elasticity, finite element or finite difference approaches. Prediction of further cracking is based on either a fracture mechanics approach or a probabilistic failure strength theory. Continuum damage mechanics are used by some investigators to model the behavior of the cracked laminate. Recent developments in this area are summarized here, and suggestions for future …