Engineering Commons^™

The Nuts & Bolts Of Cooperative Learning In Engineering, Nikos J. Mourtos

Faculty Publications

A great number of engineering students work alone. But in industry, teamwork is required most of the time. Incorporating Cooperative Learning (CL) into an engineering program gives students an opportunity to practice problem solving and communication skills in a "simulated" professional environment. The paper briefly discusses the motivation behind using CL in engineering courses. Then, the essential elements to make CL successful in the classroom are examined and examples of how these elements have been incorporated into engineering courses taught by the author are given. Problems that have been encountered along with possible fixes are also mentioned.

Numerical Design Of Advanced Multi-Element Airfoils, Donovan L. Mathias, Russell M. Cummings

Aerospace Engineering

The current study extends the application of computational fluid dynamics to three-dimensional high-lift systems. Structured, overset grids are used in conjunction with an incompressible Navier-Stokes flow solver to investigate flow over a two-element high-lift configuration. The computations were run in a fully turbulent mode using the one-equation Baldwin-Barth turbulence model. The geometry consisted of an unswept wing which spanned a wind tunnel test section. Flows over full and half-span Fowler flap configurations were computed. Grid resolution issues were investigated in two-dimensional studies of the flapped airfoil. Results of the full-span flap wing agreed well with experimental data and verified the …

Flightlines, Vol. 3, No. 1, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Computational Analysis Of Forebody Tangential Slot Blowing, Ken Gee, Roxana M. Agosta-Greenman, Yehia M. Rizk, Lewis B. Schiff, Russell M. Cummings

Aerospace Engineering

No abstract provided.

The Effects Of Channel Curvature And Protusion Height On Nucleate Boiling And The Critical Heat Flux Of A Simulated Electronic Chip, John E. Leland

Office for Research Publications and Presentations

The quest for higher power yet smaller electronics has given rise to the need for very effective cooling of these electronics. Because one of the foremost problems in electronics cooling is achieving high heat flux cooling within small packages while expending minimal pumping power, one focus of this study was to investigate the effects of channel curvature on the CHF. Experimental data were obtained for flow rates of 1-7 m/s, subcoolings of 5-35"C, and radii of curvature of 25.4 and 50.8 mm. A correlation was obtained for these data which provided an excellent fit.

One condition that has been ignored …

Flightlines, Vol. 2, No. 2, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Determination Of Flow Quality And Boundary Layer Thickness In Variable Density Wind Tunnel, Marshall Philips

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this paper is to measure the velocity profile in the test section of the Variable Density Wind Tunnel (VDWT). The hot wire anemometer is chosen to measure the velocity profile because of its accuracy and its ability to be moved relatively close to the upper and lower surfaces of the wind tunnel. Special attention is paid to the uniformity of flow velocity in the free stream and whether it varies with position in the tunnel. The measurements were taken at two different stations, two different temperatures, and three different speeds.

Results indicate that the velocity profiles are …

Development Of A Launch System For Performance Studies Of Small Aircraft Models, James J. Schneider

Opportunities for Undergraduate Research Experience Program (OURE)

This paper presents a design of a launching system that can be employed for performance studies on small aircraft models. Further the article describes a design and development of an aircraft model for use with the system. initial analysis and testing of the system using the designed aircraft model will be presented.

The Effect Of Spatial Variation Of The Turbulent Prandtl Number And Calculation Methods For Heat Transfer In High Mach Number Flows, Thomas W. Scott

Opportunities for Undergraduate Research Experience Program (OURE)

The effect of using various spatial distributions of the turbulent Prandtl number on the predicted surface heat transfer in the numerical simulation of Mach 4 flat plate flow is studied. The spatial distribution of the turbulent Prandtl number is shown to have a small effect on surface heat transfer, hence suggesting that the standard assumption of a constant turbulent Prandtl number is acceptable for high Mach number boundary layer type flows. In addition, a wall-cell control volume technique for computing heat transfer shows superior predictive capacity across the Reynolds number range when compared to the conventional calculation of surface heat …

Preliminary Efforts Towards The Analysis Of Unsteady Pressure Measurements Around Wing Models In Transonic Flow, Stephen Witherspoon

Opportunities for Undergraduate Research Experience Program (OURE)

A computer code was developed to implement methods of analyzing unsteady pressure measurements acquired from a wing model immersed in transonic flow. The code uses the fast Fourier Transform to identify phase changes and magnitudes of dominant frequencies over time in the unsteady pressure coefficients. The transformed data, as well as the raw data, are graphed and the results explained in detail identifying features depicted in the graphs. Also, the code performs some simple statistical calculations and smoothes the data to remove insignificant noise in the signal, if desired.

The Feasibility Of Using Piezoelectric Flap Actuation In The Active Control Of Flutter, Aaron Laws

Opportunities for Undergraduate Research Experience Program (OURE)

Wing flutter is one of the most important and dangerous phenomenon faced by aircraft structural design engineers. Flutter is a self exciting aeroelastic phenomenon in which portions of an aircraft structure begin to oscillate with exponentially growing amplitudes, produced by the changing aerodynamic forces and moments brought about by the deformation of the structure. There exists a characteristic flight speed, known as the flutter speed, where the structure exhibits sustained harmonic motion, ie. zero damping. Below this velocity, the vibration of the structure due to a perturbation will decrease exponentially, while above this velocity, the vibration will increase exponentially, eventually …

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.

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.

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 …

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.

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.

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 …

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.

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 …

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, …