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Ryan, E. V.

Publications and source records attributed to Ryan, E. V..

Catastrophic disruption experiments: Recent results

This paper presents a review of the progress in the field of catastrophic disruption experiments over the past 4 years, since the publication of the review paper by Fujiwara et al. (1989). We describe the development of new techniques to produce shattering impacts relevant to the study of the collisional evolution of the asteroids, and summarize the results from numerous experiments which have been performed to date, using a variety of materials for both the impactor and the targets. Some of these, such as ice-on-ice, loose aggregates and pressurized targets, are quite new and have provided novel and exciting results. Some of the gaps existing previously in the data on fragment ejection-angle distributions, as well as translational and rotational velocity fields (including fine fragments) have been filled, and these new results will be surveyed.

Martelli, G.↗

Numerical simulations of catastrophic disruption: Recent results

Numerical simulations have been used to study high velocity two-body impacts. In this paper, a two-dimensional Largrangian finite difference hydro-code and a three-dimensional smooth particle hydro-code (SPH) are described and initial results reported. These codes can be, and have been, used to make specific predictions about particular objects in our solar system. But more significantly, they allow us to explore a broad range of collisional events. Certain parameters (size, time) can be studied only over a very restricted range within the laboratory; other parameters (initial spin, low gravity, exotic structure or composition) are difficult to study at all experimentally. The outcomes of numerical simulations lead to a more general and accurate understanding of impacts in their many forms.

Benz, W.↗

Dynamic fragmentation in impacts - Hydrocode simulation of laboratory impacts

The dynamic fragmentation in impacts into solids is examined using a physical model for the formation and growth of cracks in rocks. The physical model is then inserted into a numerical model (hydrocode) of stress wave propagation and interaction, from which the outcome of a given impact event can be computed. The hydrocode model predicts fragment sizes due to impact in terms of shock waves propagating in a homogeneous elastic medium containing a distribution of crack nucleation centers known as Weibull flaws.

Melosh, H. J.↗