Shock Waves In Materials Research Articles

High-power laser beam shaping using a metasurface for shock excitation and focusing at the microscale.

Achieving high repeatability and efficiency in laser-induced strong shock wave excitation remains a significant technical challenge, as evidenced by the extensive efforts undertaken at large-scale national laboratories to optimize the compression of light element pellets. In this study, we propose and model a novel optical design for generating strong shocks at a tabletop scale. Our approach leverages the spatial and temporal shaping of multiple laser pulses to form concentric laser rings on condensed matter samples. Each laser ring initiates a two-dimensional focusing shock wave that overlaps and converges with preceding shock waves at a central point within the ring. We present preliminary experimental results for a single ring configuration. To enable high-power laser focusing at the micron scale, we demonstrate experimentally the feasibility of employing dielectric metasurfaces with exceptional damage threshold, experimentally determined to be 1.1 J/cm2, as replacements for conventional optics. These metasurfaces enable the creation of pristine, high-fluence laser rings essential for launching stable shock waves in materials. Herein, we showcase results obtained using a water sample, achieving shock pressures in the gigapascal (GPa) range. Our findings provide a promising pathway towards the application of laser-induced strong shock compression in condensed matter at the microscale.

On the mechanism of ionization of atoms at compression of a substance by front of the converging shock wave

Purpose. To study changes in the microstructure of metals after exposure to high-energy plasma jets formed by the cumulation of gas-dynamic flows in a conical target. To estimate the expected state of matter in a strong shock wave compression, taking into account the change in volumetric energy density at the moment of transformation of a solid body plasma into nuclear matter. Methodology. The technique of laser initiation of a profiled front of detonation waves in explosive charges and the corresponding profile of shock waves in materials, methods and techniques for measuring the dynamic parameters of shock-compressed substances are used. Findings. An experimental study on the physicochemical state of a substance that has been processed with extremely high pressures and temperatures during compression by converging shock waves in conical targets has been carried out. Scientific results of physical and mathematical modelling of converging shock waves are analysed. Originality. For the first time, the formation of symmetric plasma jets during gas compression in conical targets has been experimentally observed. For the first time, metallo-physical studies on the microstructure of cast iron and steel have been carried out. These studies were made after the action of high-energy dense plasma jets with a temperature of (2.52.8) × 106K and a pressure 1.12 × 1012 arising from the collision of the jet with a barrier. Iron-55 and copper-64 isotopes were found in the cast iron microstructure near the surface formed by the action of the plasma jet. The main components of the plasma jet were gaseous oxygen, nitrogen, argon, and atomic iron, copper and gold. The fact of formation of isotopes is the result of nuclear reactions. One of the main conditions for the implementation of such reactions is a dense high-temperature plasma. It is assumed that under the action of a strong shock wave in a conical target, in addition to the synthesis reaction, other nuclear reactions with heavy elements can be realized. The ideas about the expected state of matter in a compression shock wave are presented, taking into account the change in the volumetric energy density at the moment of transformation of a solid body plasma into nuclear matter. Practical value. The proposed technique for conducting experimental studies on a shock-compressed substance under the action of extreme temperatures and pressures in conical targets using laser initiation of chemical explosives is of practical importance. The idea of the expected state of matter in the shock wave is also important.

Spherically Symmetric Shock Waves in Materials with a Nonlinear Stress-Strain Dependence

The paper considers the dynamic deformation features of constructional materials with nonlinear stress-strain dependence. For the one-dimensional shock waves with nonzero curvature arising in constructions under dynamic loading the propagation regularities are studied on the basis of the matched asymptotic expansions method. In the nonstationary problem with the longitudinal spherical shock wave the relations for simultaneous consideration of dynamic properties in the outer and inner problem of the perturbation method are obtained. The solution in the front-line area is constructed on the basis of the evolution equation different from ones for a plane longitudinal wave. The need for a solving of an additional ODE system for matching outer and inner expansions is shown. It is obtained that the outer solution asymptotics in the spherically symmetric problem contains waves reflected from the leading front in contrast to the solution behavior behind the front of the plane shock wave.

Research of igdantine destruction under high-current beam of electrons with energy more than 1 MeV

Research of the composite materials destruction under extreme pulsed loads is an important task, both for different materials science applications and development of a fundamental understanding of the formation and propagation of shock waves in materials with a complex internal structure. In this paper, we present an experimental study of the interaction of a high-current electron beam with a low-modulus polymer material characterized by high elasticity. It has been demonstrated that this effect also causes multiple cracks in the peripheral regions of the sample (∼10 mm in length).

On the impact of the elastic-plastic flow upon the process of destruction of the solenoid in a super strong pulsed magnetic field

At interaction of super strong magnetic fields with a solenoid material, a specific mode of the material flow forms. To describe this process, magnetohydrodynamic approximation is traditionally used. The formation of plastic shock-waves in material in a rapidly increasing pressure of 100 GPa/μs, can significantly alter the distribution of the physical parameters in the medium and affect the flow modes. In this paper, an analysis of supporting results of numerical simulations in comparison with available experimental data is presented.

Numerical Simulation and Experimental of Residual Stress Field of SAE1070 Spring Steel Induced by Laster Shock

Laser Shock Processing (LSP) is an innovative surface treatment technology. LSP can induce compress residual stress layer in the surface of metallic materials, which is used for improving the fatigue life. In this study, the propagation course of typical laser shock wave in material was analyzed according to the theory of plasticity dynamics and the theory of stress wave. The effects of laser shock processing, residual stress of SAE1070 steel surface layer were studied. The finite element software ANSYS/LS-DYNA was applied to simulate the residual stress field of SAE1070 steel surface layer induced by laser shock processing. A bilinear isotropic model in a nonlinear inelastic model is created by using ANSYS/LS-DYNA finite element analysis software. Shock wave pressures under different peak loads are adopted to predict residual stress distribution. The experimental results for the magnitude and distribution of residual stress are consistent with the numerical simulation.

Analysis of simulation technique for steady shock waves in materials with analytical equations of state

We calculate and analyze a thermodynamic limit of a multiscale molecular dynamics based scheme that we have developed previously for simulating shock waves. We validate and characterize the performance of the former scheme for several simple cases. Using model equations of state for chemical reactions and kinetics in a gas and a condensed phase explosive, we show that detonation wave profiles computed using the computational scheme are in good agreement with the steady state wave profiles of hydrodynamic direct numerical simulations. We also characterize the stability of the technique when applied to detonation waves and describe a technique for determining the detonation shock speed.

Shock waves in materials with Dzugutov-potential interactions

The influence of shock waves on the bcc ground state, the metastable $\ensuremath{\sigma}$ phase, and quasicrystal structures of the Dzugutov potential [Phys. Rev. A 46, R2984 (1992)] has been studied by molecular dynamics. In general, a phase transition is observed to the well-known high-pressure fcc- or hcp-phase. The details of the phase transition and the perfection of the created phases depend on the orientation of the shock wave propagation direction with respect to the symmetry axes. The results are in good qualitative agreement with recent simulations with embedded atom method potentials designed specifically for iron. For the quasicrystal we observed flips, a new plasticity mode predicted for these structures. Furthermore we will report the results for an amorphous structure supplied with the same potential. No crystallization takes place in this case, indicating that it is easier to shift atomic layers collectively than to order the atoms one by one.

On shock waves in materials with memory

Shock wave propagation in materials with memory is studied through the method of discontinuities of Achenbach and Reddy [3]. We consider linear ageing and nonageing viscoelastic materials with creep-relaxation kernels containing a weak (integrable) singularity and presented by fractional models. It is shown that for this class of materials, the existence of discontinuities of any order is not possible and that the solutions behind the wavefront are infinitely smooth. This conclusion is confirmed through the integral transforms method. The obtained results are also valid for phenomenological nonlinear viscoelastic theories. The problem of the general nonlinear case is discussed. Relationships for shock wave propagation in classic viscoelastic materials (spring--pot models) follow from the presented ones as a limit case for the singularity parameter tending to zero. The established results lead to numerous applications, for example in materials science, civil and seismic engineering.

Propagation of Weak Shock Waves in Materials with Memory

The propagation of longitudinal shock waves is studied for Green-Rivlin viscoelastic materials. Significant results can be obtained only for a class of materials, almost-elastic materials. Using the integral-expansion method along with the derivative-expansion method, well-known Burgers' equation is derived as a far field equation for solid-like materials with a normal memory. For both solid-like and fluid-like materials with an anomalous memory, a far field equation becomes a new type of integro-partially differential equation. In practice, the mechanical models consisting of spring and dashpot elements are considered as concrete and manifest examples. The structure of steady shocks is examined by solving the far field equations thus obtained.

Thermodynamic relations for shock waves in materials with a linear relation between shock-wave and particle velocities

The Rankine-Hugoniot relations for shock waves and the empirical linear relation between the shock-wave and particle velocities define an incomplete thermodynamic description of the states along the Hugoniot curve. This incomplete description defines the following along the Hugoniot: (1) internal energy and pressure as functions of specific volume, (2) the ratio of enthalpy to internal energy, (3) the ratio of the changes in enthalpy and internal energy across a shock wave, and (4) the relation between the Grüneisen coefficient and the effective isentropic exponent. We use the Dugdale-MacDonald relation for the Grüneisen coefficient at low pressure, an assumed constant value for the specific heat at constant volume, and reasonable physical assumptions for extremely strong shock waves together with the incomplete thermodynamic state description to define the following along the Hugoniot: (5) the Grüneisen coefficient, (6) the effective isentropic exponent, (7) the ratio of specific heats, and (8) thermal and elastic components of pressure, temperature, and entropy. We present representative numerical values of these parameters as functions of reduced volumetric compression. We show how the solutions for these parameters define tangent planes to the surfaces of the incomplete E,P, and V and P,V, and T equations of state at each point along the Hugoniot curve.

Behaviour of the acceleration and shock waves in materials with internal state variables

The explicit expressions for the change in the amplitudes of one-dimensional acceleration and shock waves propagating through arbitrary homogeneous materials described by the strain and internal state variables/parameters/are derived. The existence of a critical amplitude β for the acceleration wave and a critical strain gradient λ for the shock wave is established. For an infinitesimal shock wave the general form of the solution of the governing differential equation is furnished. The differential equations for the amplitudes of these two kind of waves are applied to an elastic-viscoplastic material.

Growth of plane shock waves in materials with memory

The purpose of the paper is to derive sufficient conditions governing the growth and decay of plane shock waves in materials with memory. It is assumed that the plane wave moves into a region at rest under a homogeneous strain and that the direction of propagation is also a principal axis. Extensions of the results to vortex sheets are also indicated. Le but de cet article est d'établir suffisamment de conditions régissant la croissance et la décroissance d'ondes de choc planes dans des matériaux à mémoire. On suppose que l'onde plane se déplace vers une région au repos sous une contrainte homogène et que la direction de propagation est également un axe principal. L'extension de ces résultats à des plans tourbillonnaires est également indiquée. Die Aufgabe dieser Arbeit ist es, genügend Bedingungen abzuleiten, die das Wachstum und die Abnahme von ebenen Stosswellen in Stoffen mit Gedächtnis regieren. Es wird angenommen, dass die ebene Welle sich in eine Zone bewegt, die unter einer homogenen Spannung in Ruhe ist, und dass die Fortpflanzungsrichtung auch eine Hauptachse ist. Ausdehnungen der Resultate auf Wirbellagen werden auch angedeutet. Lo scopo di questo articolo è di ricavare condizioni sufficienti che regolano la crescita e lo smorzamento delle onde d'urto planare nei materiali con memoria. Si presume che l'onda planare si sposti in una regioni in riposo sotto sollecitazione omogenea e che la direzione della propagazione sia anche un asse principale. Si indicano anch estensioni dei risultati ai fogli di vortice. Цeль paбoты вывoдить дocтaтoчныe ucлoвия пpи pocтe и pacпaдe плocкич uдapныч вoлн в мaтepиaлaч c пaмятью. Пpинятo, чтo плocкaя вoлнa pacпpocтpaняeтcя в oблacть, нaчoдящююcя в пoкoe пpи дeйcтвии oднopoднoй дeфopмaции, чтo нaпpaвлeниe pacпpocтpaнeния и являeтcя глaвнoй ocью. Ыкaзaны и paзвития peзuльтaтoв к вичpeвым лиcтaм.

Thermodynamic influences on the growth of one-dimensional shock waves in materials with memory

In this paper we study one-dimensional shock waves in materials with memory, including thermodynamic influences. In particular, we derive a differential equation relating the strain and strain gradient behind the shock, and give criteria under which the wave will grow or decay.

Physical theory of the dynamic yield point of crystalline materials

1. The model of viscous damping of high-velocity dislocations leads to a realistic description of the observed macroscopic phenomena during the initial stages of plastic flow of crystalline materials at high deformation rates. It can therefore be asserted that subbarrier dislocation motion makes the primary contribution to plastic flow during these stages of deformation. 2. Data on the damping of elastic shock waves in materials are quantitatively consistent with the damping constant determined by different methods (including the damping of ultrasound). Therefore, data on the damping of elastic shock waves can be used as an independent method for evaluating the ratio of the constant for viscous damping of dislocations to the density of moving dislocations (B/N).

On the growth of one-dimensional shock waves in materials with memory

On the growth of one-dimensional shock waves in materials with memory

Thermodynamics and one dimensional shock waves in materials with memory

We consider one dimensional shock waves in materials which do not conduct heat. We show that most of the classical theory of Hugoniot curves can be broadly generalized to substances having long range, non-linear, viscoelastic memory. For example, the presence of memory does not destroy the conclusion that the jump in entropy across a shock wave of small intensity is of order three or higher in the jump in the strain. The theorems of Bethe and Weyl on shocks of arbitrary intensity also can be generalized to materials with memory.