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Current Research of Dr. Steven Schmid

Design of Orthopedic Implants

Dr. Schmid is ivolved in the design and manufacture of new types of orthopedic implants. One area deals with the design of new types of implants that are less invasive than traditional ones. For example, a new hip fracture device is under research that involves a 25 mm incision instead of the traditional 300 mm incision, and which does not require any dissection of soft tissue for implantation. Dr. Schmid is also developing new forms of bone ingrowth scaffolding using a novel manufacturing method.

Lubrication with Emulsions

Emulsions made up of oil particles dispersed in water are widely used as metal forming lubricants. Emulsion lubrication problems have conventionally been analyzed through the plating out theory, using effective viscosity relations, or by applying mixture theory. All of these approaches have serious shortcomings in real applications and none yield accurate film thickness predictions for metal forming applications. A model incorporating droplet size effects and jet spray characteristics as well as conventional tribological parameters such as lubricant properties is being investigated. Applications include elastohydrodynamic contacts (typical of hydraulics applications), and metal rolling and ironing.

Nanoscale Tribology

Lubrication, friction and wear problems have traditionally been subjects which were investigated, both experimentally and theoretically, at macroscopic scales, even though important phenomenon occur at the sub-micron level. For example, a surface asperity on a tooling surface will penetrate and plow a workpiece in an extrusion operation, but the maximum depth of penetration is only one-half a micrometer or so. Experiments with single asperities which penetrate many millimeters into a substrate have been the most direct experiments ever conducted on such problems.

Current research emphasizes single asperity plowing simulation in an atomic force microscope and correlation with a mathematical model based on the upper bound theorem of plasticity. This research is the first ever simulation of asperity plowing at length scales which are actually present in manufacturing and machine design applications of rolling, forging, extrusion, ironing, sheet metal forming, brake systems and tribological contacts of all types.

Manufacturing Processes

Dr. Schmid performs varied research in many aspects of manufacturing, especially in the tribological application of manufacturing. Recent projects include research on the mechanisms through which emulsions lubricate metal rolling and ironing, development of new friction and heat transfer models for use in finite element simulation of forging and metal working operations, simulation of metal casting processes, and novel forming and fabrication schemes for metal foams.