Mechanical Engineering Commons^™

Shell Cracking In Investment Casting With Laser Stereolithography Patterns, W. L. Yao, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents an investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography patterns. We hypothesize that shell cracking will occur when the rupture temperature of the ceramic shell is lower than both the glass transition temperature of the pattern material and the web· link buckling temperature. The hypothesis is validated by our experimental observations which confirm the numerical predictions from our finite element analysis. This provides a basis for design of the internal web geometry of a lithography pattern and evaluation of the burnout process with such a pattern. We show …

Rapid Freezing Prototyping With Water, Wei Zhang, Ming-Chuan Leu, Zhiming Ji, Yongnian Yan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid Freezing Prototyping (RFP) with water is a novel solid freeform fabrication technique that can generate three-dimensional ice objects by depositing and rapidly freezing water layer by layer. The support where necessary is made of brine whose. freezing point is lower than. pure water. After building the part, the support can be removed by utilizing the melting temperature difference between brine and water. Preliminary experiments have shown that the ice patterns produced by this technique can be used for design visualization and silicone molding. This paper will present the concept and some experimental results of the RFP process as well …

Adjustable Ice Fishing Tip-Up, Ashok Midha

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An ice fishing tip-up includes a base frame adapted to span a hole in a layer of ice over a body of water, and carrying a mast which is extendible through the hole into the water. The mast includes a shaft fixed at its lower end to a spool of fishing line and at its upper end to a cam cylinder with a helical groove formed in its outer surface. A signal staff is spring-biased to a raised position and is movable to a lowered position received in one of the convolutions of the helical groove. A pull on the …

Cell Mapping Based Fuzzy Control Of Car Parking, Tea-Quin Kim, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes the development of a near-optimal fuzzy controller for maneuvering a car in a parking lot. To generate the rules of the fuzzy controller, a cell mapping method is utilized to systematically generate near-optimal trajectories for all possible initial states in the parking lot. Based on the input-output relations of these trajectories, which represent the states and controls of the corresponding cells, a set of fuzzy rules are generated automatically. In order to result in a small number of fuzzy rules from the large amount of numerical information generated by cell mapping, grouping of trajectories is proposed and …

Belted Work Machine, J. J. Burckhartzmeyer, E. R. Crabb, T. F. Lehnhoff, A. L. Watson Jr.

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A heavy duty belt laying work machine includes a frame, a driver wheel mounted in supporting relation to the frame on each lateral side thereof, an idler wheel assembly disposed on each lateral side of the frame. The idler wheel assembly includes an idler wheel and a carry-roller, each of which is rotatably connected to an idler support arm that is pivotally mounted in supporting relation to the frame. A mid-roller is disposed on each lateral side of the frame between the driver wheel and the idler wheel assembly and rotatably connected to a mid-roller support arm mounted in supporting …

Statistical Analysis Of Structural Response Via A Quadratic Regression Model, Mahesh Balasubramanian

Masters Theses

"Described herein is the development of an efficient capability to analyze the statistics of structural responses given a description of the statistics of the input, or design, variables. In the application of interest, inputs and outputs are related through a very large finite element model. The finite element model is approximated here by a second-order hyper-surface. Developed for the quadratic relationship are expressions for response means, standard deviations and correlation coefficients. The analysis allows correlated and uncorrelated input variables, and admissible input variable distributions are normal, log-normal and Weibull.

In addition to characterizations of response means, standard deviations and correlation …

Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks In Time Domain, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A variant of the Hopfield network, called the modified Hopfield network is formulated. This network which consists of two mutually recurrent networks has more free parameters than the well-known Hopfield network. Stability analysis of this network is presented. The analysis is carried out in the time domain with an application of the Lyapunov method and robust control Lyapunov function. The current flow in the network is treated as a "control". This "controller" is shown to guarantee "a practically stabilizing control". Analysis of the Hopfield network is also included for completion.

A Class Of Modified Hopfield Networks For Control Of Linear And Nonlinear Systems, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a class of modified Hopfield neural networks (MHNN) and their use in solving linear and nonlinear control problems. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problems under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions are discussed. Numerical results for a motivating aircraft control problem (linear) are presented. Furthermore, we formulate the state-dependent Riccati equation method (SDRE) for a class of nonlinear dynamical system and show how MHNN provides the solution. …