MSU ME Bagley College of Engineering at MSU Mississippi State University

John T. Berry

John T. Berry

E. P. Coleman Professor
Mechanical Engineering Department
Mail Stop 9552, 210 Carpenter Building
Mississippi State University
Mississippi State, MS 39762
Telephone: (662) 325-7309
Fax: (662) 325-7223
E-mail: berry@me.msstate.edu

EDUCATION

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EXPERIENCE RECORD

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SPECIALTY AREAS

Materials Processing and Materials in Design and Manufacture

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RESEARCH SUMMARY

Professor Berry's research interests span a wide sector. The bulk of his publications are in the area of solidification processing and relate to computer modeling as applied to casting technology. His colleagues and former students conducted some of the pioneer work in the field of modeling the solidification of castings. He is especially interested in the production of high quality cast products both from the processing and the mechanical behavior standpoints. However, his research interests also embrace the machinability of cast products, specialized mechanical testing procedures and the manufacture of musical instruments.

Professor Berry is a member of ASME, AFS, TMS, AWS, the International Horn Society, and the Institute of Materials (UK). He is a member of the Board of Review of Metallurgical and Material Transactions and of the Editorial Board of the International Journal for Cast Metals Research. He was presented with the Distinguished Service Award of the Engineering Division of the American Foundrymen's Society in 1992. In 1986, he received the Scientific Award of the Society's Aluminum Division. In 1995 and in 2000, he presented the Silver Anniversary paper of that division at the AFS Casting Congress. Professor Berry is deeply grateful for the honors afforded him by one of the nation's key industries. Back to top

RESEARCH ACTIVITIES

Dispersed Porosity in Long Freezing Range Aerospace Alloys.  The use of cast components, especially those of complex shape, in aerospace applications has had a dramatic effect upon cost. The further lowering of cost of both power unit and airframe components will largely determine the future effectiveness of the US aerospace industry and that of its customers in remaining competitive in world markets. Door and hatch components of airframes, large load-bearing structural components of aircraft engines, and pump bodies capable of operating reliably at sub-zero temperatures in the propulsion units of space vehicles are applications where important cost reductions have taken place through shaped castings supplanting assembled and/or fabricated components.  At the same time, the increased use of structural castings in automotive applications has brought on further challenges to casting producers from both cost and quality standpoints.  Castings with resistance to fatigue failure but with excellent machinability are paramount.

The nature of the alloys concerned--multicomponent and freezing over large temperature ranges--together with the complexity of the shapes concerned, demands special care in the computer modeling of the interdendritic flows, the breakdown of which phenomenon controls the formation of dispersed porosity or micropores, which in turn abbreviate the initiation stage of fatigue cracking, or accelerate creep.

The porous dendritic structure of the mushy zone through which new liquid metal must flow has a high flow resistance. If this resistance is high enough, tensile forces may develop leading to shrinkage-driven porosity, while dissolved gases may come out of solution leading to gas-driven porosity associated with shrinkage. A number of models based on the conservation of mass and momentum for flow through porous media have been proposed. Early work in this area was based on the Darcy flow model for porous media. Currently available models include complete phenomenological mechanisms and yield a great deal of insight into the formation of porosity. However, they contain a considerable number of empirical  phenomenological features, data on which may not be available for most alloys. They are quite complicated and have not found widespread application as yet.

Recent analysis of experimental work at MSU on A356 Al-Si-Mg cast alloy has revealed some interesting conclusions. It would appear that the highest probability of being able to predict accurately the level of porosity exists when the dissolved hydrogen content is exceptionally low (<0.01 mls/100 gm).

The characterization of the dispersed porosity forming in such alloys is itself a problem of some magnitude.  Recent investigations have involved the determination of size, shape and dispersion of individual pores and the comparison of the various methods employed to determine porosity level.  Currently, projects are centered upon techniques to minimize porosity and to determine its effect upon fatigue life.

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PUBLICATIONS

Selected Recent Publications

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