Plenary Lectures

Alan Gent
Professor Emeritus of Polymer Physics and Polymer Engineering
Polymer Science
The University of Akron

Plenary Title:

Some Outstanding Problems in the Mechanics of Rubbery Solids

Plenary Abstract:

Three aspects of the deformation and fracture of rubbery materials are reviewed: large elastic deformations of a rectangular block in so-called simple shear; the effects of test temperature and tear rate on tear strength; and the marked tendency for crack splitting to occur in particle-reinforced materials. Attention is drawn to the following features:

(1) FEA calculations of the stresses set up at the bond-line of a long block in shear are quite different from those for an infinitely-long block. Attempts are made to reconcile the two results. Fracture energies are then determined for bond failure at either end of the bond [1], but the results are inconclusive—it is not clear where bond failure will occur.

(2) For all rubbery materials a direct relation is known to hold between the tear strength and the internal viscosity [2, 3]. However, the mechanism whereby high internal viscosity is translated into high strength is not understood.

(3) Finally, the phenomenon of crack splitting is described [4, 5]. It is a highly-desirable strengthening feature of rubbery solids and especially evident in particle-filled compounds. But, again, although the conditions under which crack splitting occurs are well known, the cause is obscure.

1. I. H. Gregory and A. H. Muhr, in “Finite Element Analysis of Elastomers”, ed. by D. Boast and V. A. Coveney, Prof. Engng. Publ., 1999, pp. 265-274.
2. G. J. Lake and A. G. Thomas, Chap. 5 in “Engineering with Rubber”, 2nd. ed., ed. by A. N. Gent, Hanser Press, Munich, 2001.
3. A. N. Gent and S. M. Lai, J. Polym. Sci.; Polym. Phys. Ed. 32, 1543 (1994).
4. G. J. Lake and O. H. Yeoh, J. Polym. Sci. 25, 1157 (1987).
5. A. N. Gent, M. Razzaghi-Kashani and G. R. Hamed, Rubb. Chem. Technol., 76, 122-131 (2003).

Biographical Information:

Alan N. Gent is Professor Emeritus of Polymer Physics and Polymer Engineering at The University of Akron, where he has been since 1961. He started his research career in 1949 at the British Rubber Producers’ Research Association, where he initiated a program in engineering research and also worked with R. S. Rivlin in studies of rubber physics He was awarded the Ph.D. degree by The University of London in 1955. His research has focused on the mechanics of deformation and fracture of rubber and plastics.

He has received several awards, including the Bingham Medal of the Society of Rheology (1975), the Colwyn Medal of the Plastics and Rubber Institute (1978), the 3M Award for Excellence in Adhesion Science from the Adhesion Society (1987), the Charles Goodyear Medal (1990) from the ACS Rubber Division, and the High Polymer Physics Prize (1996) from the American Physical Society. He also received the NASA Public Service Medal in 1989 for services rendered after the Challenger disaster. He has been awarded the Medal of the College de France (1990) and two honorary degrees: D. Hon. Causa, Universite de Haute-Alsace, France (1997) and D. Sc. (Hon.), De Montfort University, U.K. (1998). He was elected to the U.S. National Academy of Engineering in 1991.