Simplifying simulation software. (Engineering).

The Engineering Div. featured seven panels and presentations that focused on a variety of topics, including quality costs, coreless induction furnaces and simulation software.

In "Numerical Simulations and Experimental Study of Gassing Cycle in Gold Box Sand Coremaking Process" (03-066), presenters SI. Bakhtiyarov and RA. Overfelt, Auburn Univ., investigated the flow dynamics of the phenolic urethane amine curing process in a corebox of an inverted "U" configuration. The effect of a reduction in area of the vents was evaluated by the manual reduction of the active vent areas. In addition, experimental data on the pressure drop and friction factor for the vents was obtained as a function of the amounts of sand deposited in the vent area.

In evaluating factors affecting gassing and purging processes, the authors considered the flow pattern in a porous medium condition. Due to the complexity of the corebox, the gas velocity in the sand core was not uniform. Under certain circumstances, fingering phenomena might appear instead of a stable displacement.

A special pressure and air flowrate measurement system was designed and built to make measurements at up to 14 locations in a single experiment. The data obtained by barometric measurements was used to create contour maps of the pressure distribution in the corebox. A high pressure was found in the area adjacent to the blowtube, and a low pressure was found at the bottom of the corebox.

In the presentation, "Experimental Results to Assist in Validation of Casting Process Simulations in a Variable Gravity Environment" (03-091), presenters V. Demas, Univ. of California--Berkeley, K.F. Packer, Packer Engineering, J. Shah, K+P Agile, Inc., and James Conley, Northwestern Univ., discussed their experimentation on the progress of computer simulation of the casting process to predict the behavior of analog material systems in both terrestrial and extra-terrestrial environments.

According to the authors, a robust casting simulation model should be able to predict pressurized cavity filling and solidification behavior of analog materials with or without the force of gravity. In the experiment, the observed terrestrial solidification behavior of the analog system is compared to the existing simulation software predictions.

During the experiments, several milestones were accomplished:

* experiments were conducted aboard NASA's KC-135 microgravity aircraft, enabling the collection of data appropriate for use in validating casting process simulation packages;

* the various results of this work have been made available to the public, and work with the code developers is part of the ongoing effort to validate software and provide an insight as to what is needed to create a robust code;

* the base for future work has been set.

In "Numerical Simulation of Squeeze Molding and Air Impact Molding with the Finite Element Method" (03024), Z. Yifei and W. Junjiao discussed ways to simulate the green sand molding process numerically. According to the presenters, the Nonlinear Finite Element Method is an effective numerical method to solve problems that can arise through materials' nonlinearity, geometrical nonlinearity and contact nonlinearity.

For manufacturing near net shape castings, it is necessary to optimize the green sand compaction process. To carry out the research and development of the compaction processes with testing only is expensive and time consuming. According to the presentation, numerical simulation of green sand compaction processes is a useful tool to cut down time and expenses.

The presenters found that although the calculated results are mainly in accordance with the testing ones, there are still some errors to the process. Possible reasons for this include:

* the constitutive relationship used in the calculation has some errors. As the material characteristics of green sand are very complicated, bisolinearity constitutive relationship has been applied for simplifying the actual condition, which brings some errors;

* as the compaction of green sand mold is a complicated process, there may have been some errors in the experiments.