For a one-dimensional fluid model where the pair interaction potential between the molecules consists of a hard core and an exponential attraction, Kac has shown that the partition function can be determined exactly in the thermodynamic limit. In Sec. II this calculation is reviewed and further discussed. In Sec. III, we show that in the so-called van der Waals limit when the range of the attractive force goes to infinity while its strength becomes proportionally weaker, a phase transition appears which is described exactly by the van der Waals equation plus the Maxwell equal-area rule. In Sec. IV the approach to the van der Waals limit is discussed by an appropriate perturbation method applied to the basic integral equation. The perturbation parameter is the ratio of the size of the hard core to the range of the attractive force. It is seen that the phase transition persists in any order of the perturbation. The two-phase equilibrium is characterized by the fact that in this range of density, the maximum eigenvalue of the integral equation is doubly degenerate and that the corresponding two eigenfunctions do not overlap. In Sec. V we comment on the relevance of our results for the three-dimensional problem.

We review limiting models for fracture in bundles of fibers, with statistically exists, but we show for a particular threshold distribution how the avalanche distribution can nevertheless be explicitly calculated in the large-bundle limit.

A bundle of many parallel fibers, with stochastically distributed thresholds for individual fibers, is loaded until complete failure. Equal load sharing is assumed. During the breakdown process, bursts of several fibers breaking simultaneously at a given load occur. We determine the expected number of such bursts before complete failure, as well as the frequency of bursts in which A fibers break simultaneously. This distribution follows asymptotically a universal power-law A~5 /2 , for any statistical distribution of the individual fiber strengths. Downloaded From: http://appliedmechanics.asmedigitalcollection.asme.org/ on 05/25/2015 Terms of Use: http://asme.org/terms Journal of Applied Mechanics DECEMBER 1992, Vol. 59 / 913 Downloaded From: http://appliedmechanics.asmedigitalcollection.asme.org/ on 05/25/2015 Terms of Use: http://asme.org/terms

No abstract