N. Cristescu – författare

Dynamic Plasticity discusses the problems encountered in the theory of dynamic deformation of plastic bodies. The book describes one-dimensional problems involving a single component of stress, particle velocity, and single spatial coordinate. The propagation of longitudinal elastic-plastic waves in thin rods or wires is a simple example of this problem of dynamic plasticity. Another one-dimensional problem, which has various possible transverse motions, is the dynamics of extensible strings. This problem is associated in calculations dealing with cables of suspension bridges, of elevator cables, of electric cables. The analogy with the mechanics of extensible strings can be extended to circular and rectangular membranes such as explained by Karunes and Onat. Karunes and Onat analyzed the propagation of transverse and longitudinal shock waves in such membranes using the Rakhmatulin theory for strings. The text also discusses axi-symmetrical problems and the problems of soil mechanics when applied to soft soils. The book can prove valuable to civil engineers, structural engineers, physicist, and students of mechanical engineering or industrial design.

The present book is the result of work carried out over a period of about ten years by the author and his co-workers in order to describe more accurately the slow irreversible deformation in time of the rocks surrounding underground openings. To begin with, our efforts were directed toward a better under­ standing of the mechanical behaviour of rocks and to the formulation of more precise mathematical models for their dominant mechanical properties, mainly irreversible dilatancy and/or compressibility during creep. Subsequent efforts were focused on finding improved solutions to important mining and oil engineering problems, such as, for instance, the creep of rocks around wells and tunnels, short-term failure which may occur around an underground opening, damage and failure which take place after long-time intervals, the tunnel support analysis incorporating rock creep, etc. The book is the result of a great number of questions posed either by mining engineers or by the author himself, and of the corresponding answers (unfor­ tunately often only partial answers). This dialogue must certainly be continued in order to improve the models and to formulate models for other kinds of rocks, or, ultimately to obtain solutions for other important engineering problems. It is hoped that the book will also contribute to a better description, by means of mathematical models, of the mechanical behaviour of rocks.

The present book is the result of work carried out over a period of about ten years by the author and his co-workers in order to describe more accurately the slow irreversible deformation in time of the rocks surrounding underground openings. To begin with, our efforts were directed toward a better under­ standing of the mechanical behaviour of rocks and to the formulation of more precise mathematical models for their dominant mechanical properties, mainly irreversible dilatancy and/or compressibility during creep. Subsequent efforts were focused on finding improved solutions to important mining and oil engineering problems, such as, for instance, the creep of rocks around wells and tunnels, short-term failure which may occur around an underground opening, damage and failure which take place after long-time intervals, the tunnel support analysis incorporating rock creep, etc. The book is the result of a great number of questions posed either by mining engineers or by the author himself, and of the corresponding answers (unfor­ tunately often only partial answers). This dialogue must certainly be continued in order to improve the models and to formulate models for other kinds of rocks, or, ultimately to obtain solutions for other important engineering problems. It is hoped that the book will also contribute to a better description, by means of mathematical models, of the mechanical behaviour of rocks.