|
|
| Engineering Physics : Faculty : | |
| Millard W. Johnson, Jr. |
| Millard W. Johnson, Jr. Professor Emeritus |
| 3346 Engineering Hall 1415 Engineering Drive Madison, WI 53706-1691 |
 |
Tel: 608/262-0623 Fax: 608/238-0019 E-mail: millard@engr.wisc.edu |
Professor Millard W. Johnson, Jr. has published papers on the theory of elasticity, non-Newtonian fluid mechanics, the mechanics of paper and numerical methods in mechanics. His interests in rheology localization effects in the flow of viscoelastic fluids and lubrication theory. He is also interested in large deformations of plates and shells with application to the mechanics of paper.
Johnson's group has developed a lubrication theory for the power-law fluid and used it to study piston ring lubrication. Current work considers the thin film flow in the entrance and exit regions as well as under the ring. Experimental data on film thickness indicate that surface tension may play an important role in the entrance and exit regions. If large surface tension is assumed, it is possible to use lubrication theory in the entrance and exit regions. This formulation results in an equation for the shape of the free streamline which is an extension of a well known equation used to study the motion of liquid drops on surfaces. The equation is very stiff and numerical methods for its solution are under investigation.
Professor Johnson has extended the above lubrication theory to allow for vaporization at the free surface of the fluid. It is intended to use this theory to study the loss of lubricating fluid to the
In 1977 Professor Johnson and Dan Segalman proposed a non-affine constitutive equation for viscoelastic fluids which exhibits, in shear flow, shear thinning, stress overshoot and realistic normal stresses. A variation of it was later found by Professor Malkus and his co-workers to exhibit localization effects in shear flows such as step strain and pressure driven flow. This research is ongoing. An extension of this model under investigation examines vorticity effects in a constitutive equation.
Several years ago, Johnson proposed a constitutive equation for the elastic behavior of paper sheets which included the effects of large deformation and material orthotropy. This theory has proved useful in examining the buckling of paper sheets under compression and in developing a theory for the strength of fiberboard under compressive loading. Currently, this theory is being extended to include three dimensional and viscoelastic effects. This will enable the study of problems such as the stress state in thick walled cylinders under rapid rotation and under radial loads.
Professor Johnson's group has contributed 60 journal articles to the rheological literature.
|
|
Copyright 2005 The Board of Regents of the University of Wisconsin System Date last modified: Monday, 31-Jul-2000 10:59:17 CDT Content by: millard@engr.wisc.edu Thank you for visiting /ep/faculty/johnson_millard.html |
