The dynamic coupled thermoelastic problem formulation and the thermodynamically consistent theory of inelastic behavior of materials are used to solve an axisymmetric problem for a steel disk subject to a heat pulse at the center. The temperature dependence of the physical and mechanical properties of the disk is taken into account. The problem is solved by the FEM. The evolution in time and features of the strain-stress and thermal states of the disk and the dynamic effects accompanying the processes of heating and gradual cooling are studied Keywords: impulsive thermal irradiation, coupled thermomechanics, dynamic effects, pulse propagation, inelastic behavior Introduction. One of the distinctive features of modern engineering is the reduced dimensions and weight of articles and mechanisms. Miniaturization is invoked to enhance the quality, reliability, and life of parts manufactured. Such trends are dictated by the material-and energy-saving requirements and new opportunities for creating advanced cars, mechanisms, and devices based on the recent scientific achievements. In this connection, a great deal of effort is going into the development of test and diagnostic aids and into microengineering, which owes its development to micro and nano materials-processing technologies. Of extreme interest are nonconventional methods such as laser-shock or pulsed electron-beam processing [12,[16][17][18].Promising fields for use of short laser or electron-beam pulses are (i) strength enhancement, wear prevention, and performance improvement [4]; (ii) micro-and nanodiagnostics [21,22]; (iii) surface cleaning and precision nesting [4]; and (iv) micro-and nanoforming and quasistatic and dynamic molding [4,13]. In all cases, the process is based on optimal and precisely metered power supply to the workpiece and, hence, extremely precise and localized load on the stress-strain, thermal, or aggregate state of a structural element.By localizing laser or electron-beam energy in space and time, it is possible to produce highly concentrated irradiation power and, thus, to implement various energy-deposition mechanisms for various types of material processing [4]. Radiation is localized in space by means of various optical systems and in time by reducing the pulse duration. The ordinary laser power supplies produce pulse durations from several milliseconds (10 -3 sec) to several tens of microseconds (10 -6 sec). Special mechanical, optoelectric, or acoustoelectric Q-switches make it possible to generate so-called giant pulses (with very high peak power) lasting from several nanoseconds (10 -9 sec) to several hundreds of nanoseconds [4]. Recently, researchers have managed to generate even shorter pulses of picosecond (10 -12 sec), femtosecond (10 -15 sec), and even attosecond (10 -18 sec) duration [14,20].There are two main thermomechanical effects produced by laser or electron-beam radiation on an object. One is partial evaporation of the surface material and production of plasma. Expanding away from the irradiated surface, the plas...

Nonstationary axisymetric waves in a disk excited by an impulsive radial load are analyzed numerically. The nonlinear deformation of the material is described by the Bodner-Partom model. The model parameters are derived from experimental data for samples subjected to tension followed by compression over a wide range of strain rates. The temporal and spatial characteristics of the wave process are studied. The influence of hardening on wave focusing and residual strain distribution is examined Keywords: nonstationary waves, physically nonlinear material, disk, impulsive loading, finite-element methodIntroduction. Many structural members in modern technology are cylindrical bodies that, while in service, experience impulsive loads, which induce inelastic residual strains. Strength evaluation of such structures calls for stress-strain analysis methods that would allow for the rheological behavior of the material, the geometry of the body, and nonstationary loads acting on it.Analysis of residual stress-strain state (SSS) of bodies under impulsive loading is of considerable theoretical and practical interest [20,21]. These problems play a crucial role in the fatigue crack arresting techniques currently under development. They use an impulsive, explosion load with energy focused at the crack tip to induce compressive residual stresses and plastic strains [10].Research in this field is also motivated by the needs of explosion welding [5]; impulsive straightening of thin-walled structures, including welded ones [6,27]; surface hardening [15,22]; etc. In all these applications, the prime objective of calculations is to determine the appropriate process parameters. New technologies also require studying the influence of dynamic processes on the kinetics of microstructural transformations in materials [18, 28, etc].In studying nonstationary dynamic processes, reliable results can be obtained by accomplishing two basic tasks. One is to select and specify constitutive equations for fast (10 10

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