G. Scott Duncan

Three-Component Receptance Coupling Substructure Analysis for Tool Point Dynamics Prediction

In this paper we present the second generation receptance coupling substructure analysis (RCSA) method, which is used to predict the tool point response for high-speed machining applications. This method divides the spindle-holder-tool assembly into three substructures: the spindle-holder base; the extended holder; and the tool. The tool and extended holder receptances are modeled, while the spindle-holder base subassembly receptances are measured using a “standard” test holder and finite difference calculations. To predict the tool point dynamics, RCSA is used to couple the three substructures. Experimental validation is provided.

ROTATING TOOL POINT FREQUENCY RESPONSE PREDICTION USING RCSA

This article describes the prediction of rotating tool point frequency response functions using receptance coupling substructure analysis (RCSA). In this approach, the at-speed spindle-machine dynamics are identified by impact tests of a rotating cylindrical standard artifact. After removing the portion of the artifact beyond the holder flange in simulation, models of arbitrary tool-holder combinations are coupled to the spindle response to predict the speed-dependent tool point frequency response. Given this information, process dynamics predictions for spindles that exhibit dynamic changes with rotating speed are made possible without detailed knowledge of the spindle geometry, assembly tolerances, etc. Experimental results and comparisons with prediction are provided.

An Approach for Micro End Mill Frequency Response Predictions

A method for predicting the tool point frequency response of a tool-holder-spindle system is provided. Receptance coupling is used to analytically combine responses for the tool, holder, and spindle substructures and predict the assembly dynamics. The spindle response is determined using experimental procedures, while the holder and tool are modeled using Timoshenko beams. With the use of this method, predictions may be completed for micro scale end mills where impact testing is inconvenient. Experimental results are provided.Copyright

A Solar Thermal Electrolytic Reactor for Studying the Production of Metals From Their Oxides

A solar thermal electrolytic reactor was developed for studying at a 10 kW scale how a solar reactor’s electrolytic cell design and operating variables influence the performance of a solar process for producing metals from their oxides. Current versus voltage maps as well as current versus time for specified voltages were obtained for the electrolysis of ZnO and MgO within the temperature range of 1200–1500 K and various electrolytic cell configurations. An example of a map is presented. The data from maps and steady-state runs were used to illustrate how we quantify the influence of the cell’s operating temperature and current density on process performance. We also illustrate how one design variable, the cell’s electrolyte, influences process performance.

A High-Flux Solar Furnace for Undergraduate Engineering Education and High-Temperature Thermochemistry Research

The optical design and engineering features of a 10 kW solar furnace now operational at Valparaiso University are described. The solar furnace is anticipated to achieve a mean concentration ratio of 3000 suns over a 6 cm diameter focus. It will support high-temperature solar chemistry research and undergraduate engineering pedagogy. Many of the components of the solar furnace were designed and constructed by undergraduate engineering students. Some of these students cite their participation in the solar furnace project as the motivating factor for continuing to work in the area of energy science in industry or graduate school.Copyright

A Control Systems Laboratory for Undergraduate Mechanical Engineering Education

This article describes seven laboratory experiments that have been developed for the automatic controls course at Valparaiso University. It also presents the results of a self-assessment survey taken by the students after they had done these laboratory experiments. Automatic controls recently became a required course for all undergraduate mechanical engineering students. When taught as an elective, it was noticed that many students tended to struggle with this class. Most students perceive this class to be a collection of different mathematical tools without any application or use in their future careers. To alleviate this situation and assist students in visualizing control systems in practical situations, a half-credit elective control laboratory, which consists of five experiments and two laboratory projects, has been developed. These experiments will help students to understand the application of this topic and to learn to develop appropriate mathematical models and control routines in closed-loop systems with computers in the loop.

Optimal Design of a Helmholtz Resonator With a Flexible End Plate

A multi-objective optimization formulation to design a Helmholtz resonator with a flexible end plate is studied. The optimization formulation generates a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem is formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate is completed based on the design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume are defined as optimization objectives. Finally, the Pareto curve of optimum design solutions is calculated using a gradient-based approach via the e-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, one optimal Helmholtz resonator is manufactured and experimentally confirmed.Copyright