Mechanical Engineering Commons^™

A New Neural Architecture For Homing Missile Guidance, S. N. Balakrishnan, Victor Biega

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present a new neural architecture which imbeds dynamic programming solutions to solve optimal target-intercept problems. They provide feedback guidance solutions, which are optimal with any initial conditions and time-to-go, for a 2D scenario. The method discussed in this study determines an optimal control law for a system by successively adapting two networks - an action and a critic network. This method determines the control law for an entire range of initial conditions; it simultaneously determines and adapts the neural networks to the optimal control policy for both linear and nonlinear systems. In addition, it is important to know that …

A Recursive Least Squares Training Algorithm For Multilayer Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Recurrent neural networks have the potential to perform significantly better than the commonly used feedforward neural networks due to their dynamical nature. However, they have received less attention because training algorithms/architectures have not been well developed. In this study, a recursive least squares algorithm to train recurrent neural networks with an arbitrary number of hidden layers is developed. The training algorithm is developed as an extension of the standard recursive estimation problem. Simulated results obtained for identification of the dynamics of a nonlinear dynamical system show promising results.

Identification Of Cutting Force In End Milling Operations Using Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of identifying the cutting force in end milling operations is considered in this study. Recurrent neural networks are used here and are trained using a recursive least squares training algorithm. Training results for data obtained from a SAJO 3-axis vertical milling machine for steady slot cuts are presented. The results show that a recurrent neural network can learn the functional relationship between the feed rate and steady-state average resultant cutting force very well. Furthermore, results for the Mackey-Glass time series prediction problem are presented to illustrate the faster learning capability of the neural network scheme presented here

Automation Of The Electrostatic Aerosol Classifier And The Continuous Flow Cloud Diffusion Chamber, Daron W. Dryer

Opportunities for Undergraduate Research Experience Program (OURE)

Analyzing cloud condensation nuclei through the use of a Continuous Flow Thermal Diffusion Cloud Chamber (CFD) and an Electrostatic Aerosol Classifier (EAC) can be very time consuming. An alternative to manually monitoring these devices is to automate the equipment, thus freeing personnel for other research as well increasing CCN data collection.

Automation of the EAC will be carried out by digital command through the use of a Quick Basic program. This program will be run from an IBM personal computer outfitted with a digital input/output board.

RS-485 Standard will also be incorporated into the Quick Basic program in order to …

A Computer Graphic Teaching Aid For The Synthesis Of Four-Bar Linkages, Sew K. Woon

Opportunities for Undergraduate Research Experience Program (OURE)

This project involves developing software for the use as a teaching tool in the classroom. The "four-bar linkage mechanism", often used in kinematic movement, is the main subject

The software provides a working environment to perform a graphical synthesis of a four- bar linkage to move one of the links through three specified positions in the plane. The construction process is facilitated by the built in kinematic intelligence so that the student can quickly and easily visualize the process. The construction lines are dynamically updated as the free parameters in the design are modified. This is particularly beneficial because it …

Fabrication Of Composite Laminates With Embedded Pizo-Ceramic Sensors And Actuators, Todd Nelson Kelsheimer

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of the research project is to investigate the methods for embedding pizo-ceramic sensors and actuators in a composite ( a fiber reinforced epoxy matrix). The importance of these sensors and actuators is vital in controlling the vibration and excessive strain on a structure causing fatigue or failure. With the control of these instabilities by the actuator, proper performance of the structure is achieved. Most sensors and actuators are surface mounted because (1) The sensor can pick up the greatest strain on the surface of a structure. (2) The actuator can create a stronger moment to counter balance the …

Improved Techniques For Manufacturing Layered Laminate Composite Materials, Michael D. Grabber

Opportunities for Undergraduate Research Experience Program (OURE)

An increasingly important class of engineering materials are known as fiber reinforced composite materials. They offer outstanding mechanical properties, unique flexibility in design, and ease of fabrication. Because of this, fiber reinforced composites are being found more and more in such diverse applications as aircraft, space vehicles, automobiles, sporting goods, and appliances.

The main objective of this research project was to develop a procedure for which high quality composite plates could be manufactured. The procedure needed to be able to accommodate materials of various thicknesses as well as various sizes. We also wanted the procedure to be versatile enough to …

Free Vibrations Of A Piezoelectric Body, J. S. Yang, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present a systematic analysis of the eigenvalue problem associated with free vibrations of a finite piezoelectric body. The analysis is based on an abstract formulation of the three-dimensional theory of piezoelectricity. A series of fundamental properties of free vibrations of a piezoelectric body are proved concisely. The problem of free vibrations of a piezoelectric plate governed by the two-dimensional plate equations due to Mindlin is treated in a similar manner. © 1994 Kluwer Academic Publishers.

Experiences In The Integration Of Design Across The Mechanical Engineering Curriculum, Ashok Midha, J. M. Starkey, D. P. Dewitt, R. W. Fox

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Faculty of the School of Mechanical Engineering at Purdue University have effected a major change in the Purdue Mechanical Engineering program by integrating design throughout the curriculum. In doing so, a significant level of faculty interaction has been achieved as well. The goals of the curriculum revision are: (1) to improve student skills in how to solve open-ended design problems, (2) to reduce the core of the curriculum to allow flexibility in course selection, and allow time for solving design problems, (3) to improve student skills in team work and communications, and (4) to improve student skills in using …

Use Of Hopfield Neural Networks In Optimal Guidance, S. N. Balakrishnan, James Edward Steck

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Hopfield neural network architecture is developed to solve the optimal control problem for homing missile guidance. A linear quadratic optimal control problem is formulated in the form of an efficient parallel computing device known as a Hopfield neural network. Convergence of the Hopfield network is analyzed from a theoretical perspective, showing that the network, as a dynamical system approaches a unique fixed point which is the solution to the optimal control problem at any instant during the missile pursuit. Several target-intercept scenarios are provided to demonstrate the use of the recurrent feedback neural net formulation.

Buckling Of A Coating Bonded To A Round Bar Subjected To Axial Extension. Mech. Mater. 15 (1993) 131-138, C. W. Bert, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Optimal Design Of Laminated Plates And Shells, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Designing structures made out of composite materials represents a challenging task, since not only the thickness of the element must be determined to satisfy the constraints of the problem, but, in addition, the number of plies in the laminate and their relative orientation must also be selected. Because of their strong anisotropy, a careful selection of lay-up is required to make the best use of the capabilities of the material. In this article the optimum design of laminated plates and shells subjected to constraints on strength, stiffness, buckling loads, and fundamental natural frequencies are examined. © 1994.

On The Propagation Of A Shear Band In A Steel Tube, R. C. Batra, Xiangtong Zhang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Marchand and Duffy tested thin-walled steel tubes in a split Hopkinson torsion bar at a nominal strain-rate of approximately 1600/s and could not determine conclusively whether a shear band initiating at a point in the tube propagated around the circumference in one direction or in both directions. They estimated the speed of propagation to be 520 m/s in the former case and 260 m/s in the latter. Here we simulate their test numerically and find that the shear band propagates in both directions around the circumference of the tube. When the tube is twisted at a nominal strain-rate of 5000/s, …

Approximate Analytical Guidance Schemes For Homing Missiles, S. N. Balakrishnan, Donald T. Stansbery

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Closed form solutions for the guidance laws are developed using modern control techniques. The resulting two-point boundary value problem is solved through the use of the state transition matrix of the intercept dynamics. Results are presented in terms of a design parameter.

Adaptive Critic Based Neural Networks For Control, Victor Biega

Masters Theses

"Dynamic Programming is an exact method of determining optimal control for a discretized system. Unfortunately, for nonlinear systems the computations necessary with this method become prohibitive.

This project investigates the use of adaptive neural networks that utilize dynamic programming methodology to develop near optimal control laws. First, a one dimensional infinite horizon problem is examined. The first part of this thesis considers problems involving cost functions with final state constraints for one dimensional linear and nonlinear systems. It also investigates a two dimensional linear problem. In addition to these examples, an example of the corrective capabilities of critics is shown. …

Impact On Laminated Composites: Recent Advances, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Impact damage in structures made out of composite materials is a major concern since such damage can be introduced during the life of the structure, and its mechanical properties can be drastically reduced as a result. In a previous review of the literature on impact on composite materials, this author considered 285 published before 1989. In this article over 300 articles most of which appeared after 1989 are reviewed. These figures indicate that this is a very active area of research, and the present paper seeks to present a comprehensive view of the latest developments. Taken together, these two reviews …

On The Interface Stability Of A Neck Propagating In A Sheet Reinforced With Shape-Memory Fibers, C. Q. Ru, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We propose a simple model of necking in a sheet reinforced with straight fibers made of a shape-memory alloy and examine conditions under which the interface between the necked and the unnecked region is morphologically stable. We use the Mullins and Sekerka (1963, J. Appl. Phys. 34, 323-330; 1964, J. Appl. Phys. 35, 444-450) method, established for studying the stability of a moving interface in a solidification problem, to investigate the interface stability of a propagating neck. It is found that the moving straight interface is morphologically stable for several typical cases even in the absence of surface-tension effects, and …

A Kinematically Intelligent Blackboard For Computer Aided Instruction, J. Keith Nisbett, D. Watkins, Clark R. Barker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A CAI (computer-aided instruction) package is being developed to be used as a classroom tool for the instruction of undergraduate mechanical engineering students in an introductory kinematics of mechanisms course. This graphical environment allows the instructor to emulate on the projected graphics screen everything that is currently done on the blackboard for planar mechansims. Unlike the blackboard, the software will have the intelligence to interpret the drawings in a kinematic sense so that the drawing of the linkage will behave as a linkage. The software environment involves three principal components: (1) a sketching method for defining the linkage, (2) the …

The Research, Design And Production Of Cortical Bone Pins And Screws For The Fixation Of Broken Bones In The Hand And Wrist, Ronald P. Holland

Opportunities for Undergraduate Research Experience Program (OURE)

Investigators at the University of Missouri at Rolla have entered into a joint venture with surgeons at Saint Louis University Hospital to develop a superior method of fixing broken bones of the human hand and wrist. This method involves the production of pins and screws from human cortical bone which will be used to fix broken bones for healing. The cortical bone fasteners will provide many advantages to the currently used metal fasteners. To date, prototype fasteners have been developed and are pending mechanical testing as a result of this undergraduate research project. Results of this project potentially include a …

Motorized Throttle Plate, John D. Crawford

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of this project was to develop a throttle plate mechanism that can be used to simulate transient engine operation. This throttle plate was designed so as to regulate the quantity of air flow entering a Port Fuel Injected (PFI) spark ignition engine prior to the combustion of the fuel-air mixture. The throttle plate is linked to a data acquisition system in order to study the port fuel injection characteristics of the fuel-air mixture. This data acquisition system links the throttle plate angular position information to data obtained using a nonintrusive laser based diagnostic technique, therefore enabling the study …

Performance Analysis For The Ccn Collection Apparatus, Deborah K. Bircher

Opportunities for Undergraduate Research Experience Program (OURE)

This paper concerns the performance testing of a system to collect and chemically analyze cloud condensation nuclei (CCN). These are the atmospheric particles which nucleate cloud drops.

The air is humidified by passage through the "haze chamber", consisting of parallel vertical plates that are covered with cotton cloth and are kept wet by water supplied at the top edge. The plates are adiabatic , and should equilibrate in temperature at the wet bulb temperature of the incoming air. Measurements of the plate temperature with eighty thermocouples indicate behavior consistent with theory.

Another part of the system is called the CFD …

Two Methods For Attenuation Of Vibration In Structures, Kevin Mark Mcclendon

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this report is to discuss methods of suppressing vibration in space trusses. The discussion is centered on the approach, structural attributes, and effectiveness of each method. One approach uses structural active members which are actuated to produce “anti-vibration” to cancel vibrations in the truss. The other method is to implement passive and active damping devices at the base of the space truss, where it will absorb vibrations by fluctuating the stiffness of the structures foundation.

Damage Assessment Of Composite Structures With Embedded Optical Fibers, Peter E. Hackett

Opportunities for Undergraduate Research Experience Program (OURE)

One of the important features of smart composite structures is their capability to observe their own performance for proper functioning and self-diagnostic purposes. The low velocity impact damage of composite structures (matrix cracking, fiber breakage, delamination, etc.) is often difficult to detect visually and can significantly reduce the strength of the structure. The objective of this research is to develop a technique for fabricating composite laminates that will facilitate the embedment of optical fibers. Composite test specimens will be fabricated in the composite material laboratory. The fabrication of composite laminates with a health monitoring and damage assessment system capable of …

Active Buckling Control Of Composite Plates, Bradley Wayne Gentelin

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of the research project is to investigate the feasibility of using the rapidly growing technology of smart materials in actively controlling the buckling of laminated composite plates. Advanced composite structures are susceptible to structural instabilities under compression loadings, and the proper control of such instabilities is essential to the effective performance of the structures. The focus of the research activity is to perform an experimental study of using embedded piezoelectric materials for enhancing the critical buckling loads of laminated composite plates. The forces induced by the piezoelectric actuators under the applied voltage fields will be used to counterbalance …

Catalysis Of Charcoal Emissions, James M. Horak

Opportunities for Undergraduate Research Experience Program (OURE)

This paper is about the development of a system to reduce the emissions of charcoal kilns with the catalyst from automotive catalytic converters. This device, called the charcoal kiln emissions oxidizer (CKEO), was designed and fabricated to meet the goal of a cost effective means to reduce the carbon monoxide and hydrocarbon emissions from charcoal kilns. Testing of the CKEO was never carried out as a test site could not be secured by this writing. The need for the CKEO, the theory behind it, and a procedure to test it are presented.

Analytical Guidance Laws And Integrated Guidance/Autopilot For Homing Missiles, S. N. Balakrishnan, Donald T. Stansbery, J. H. Evers, J. R. Cloutier

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approach to integrated guidance/autopilot design is considered in this study. It consists of two parts: 1) recognizing the importance of polar coordinates to describe the end game in terms of problem description and measurement acquisition, the terminal guidance problem is formulated in terms of polar coordinates; 2a) through the use of the state transition matrix of the intercept dynamics, a closed form solution for the transverse command acceleration is obtained; and 2b) through a commonly used approximation on time-to-go and a coordinate transformation, a family of proportional navigation optimal guidance laws is obtained in a closed form. A typical …

On Minimizing Thermal Deflections Of Laminated Plates, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Thermal deflections of symmetrically laminated plates that are continuous over many line supports are determined using the Rayleigh-Ritz method. The constitutive equations and the thermal loads are expressed in terms of four non-dimensional lamination parameters. Layups that minimize thermal deflections are determined for several types of composite plates subjected to temperature increases that vary linearly through the thickness.

Computer Simulation Of Three-Dimensional Mechanical Assemblies: Part I - General Formulation, Yong Fang, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In Part I of this paper, a dynamic modeling system for the simulation of three-dimensional mechanical assemblies is presented. With this simulation tool, a designer can interactively create an assembly of mechanical components ready for dynamic analysis. The modeling system presented in this paper include» the derivation of the equations of motion of spatial multi-body systems, and the formulation of the equations to model the associated collision detection and collision responses. Part II of this paper is to introduce the geometry modeling and computer simulation of 3D systems.

Computer Simulation Of Three-Dimensional Mechanical Assemblies: Part Ii - Computer Simulation, T. C. Chou, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Computer simulation of the kinematic and dynamic behaviors of mechanical assemblies has become a very important tool in design and manufacturing, because the designer can foresee how a product is going to perform before the product is actually fabricated. However, up to now, the most current simulation modules are based on analysis from another kinematic or dynamic module by specifying the mating conditions between components, and then displaying the motion on the screen. This computer simulation actually performs similarly to a movie and can only provide visual checking. The drawback of this simulation approach is that designers are forced to …

On The Use Of Levy's Method For Symmetrically Laminated Composite Plates, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

For rectangular plates with two opposite edges simply supported and no bending twisting coupling, Levy's method can yield exact solutions for static deflections, free vibrations and buckling loads. However, three distinct solutions are obtained, depending on the relative magnitude of the plate rigidities, which in turn are functions of material properties, laminate thickness and lay-up. In this communication a stiffness invariant formulation is used to identify those laminates which fall under the three cases defined. © 1993.