Analysis of penetration of axisymmetric projectiles into semi-infinite targets

The process of penetration of a projectile into a semi-infinitetarget is studied in this paper. Using certain assumptions, the propagation of plastic wave in the target is analyzed and the pressure on the surface of penetrator is given. The results calculated from the formulas of this paper agree well with experimental data and numerical results.     

Stress concentration around a spheroidal crack caused by a harmonic wave incident at an arbitrary angle

A method is proposed to study the stress concentration around a shallow spheroidal crack in an infinite elastic body. The stress concentration is due to the diffraction of a low-frequency plane longitudinal wave by the crack. The direction of wave propagation is established in which the combined concentration of mode I and mode II stresses is maximum __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 1, pp. 70–77, January 2006.     

Propagation of longitudinal elastic waves in composites with a random set of spherical inclusions (effective field approach)

The work is devoted to the problem of plane monochromatic longitudinal wave propagation through a homogeneous elastic medium with a random set of spherical inclusions. The effective field method and quasicrystalline approximation are used for the calculation of the phase velocity and attenuation factor of the mean (coherent) wave field in the composite. The hypotheses of the method reduce the diffraction problem for many inclusions to a diffraction problem for one inclusion and, finally, allow for the derivation of the dispersion equation for the wave vector of the mean wave field in the composite. This dispersion equation serves for all frequencies of the incident field, properties and volume concentrations of inclusions. The long and short wave asymptotics of the solution of the dispersion equation are found in closed analytical forms. Numerical solutions of this equation are constructed in a wide region of frequencies of the incident field that covers long, middle, and short wave regions of propagating waves. The phase velocities and attenuation factors of the mean wave field are calculated for various elastic properties, density, and volume concentrations of the inclusions. Comparisons of the predictions of the method with some experimental data are presented; possible errors of the method are indicated and discussed.     

Strong explosion near a parallelepipedic structure

The purpose of this paper is to report the blast loading characteristics resulting from the detonation of a stoichiometric propane–oxygen mixture, and to validate the approach which relies on simulating TNT explosions at large scale by small-scale experiments of gaseous explosions. Several dimensionless correlations are obtained from experimental data. These relationships allow determination of the parameters of a blast wave interacting with a structure as a function of the positions of the explosive charge and the structure. Simulations carried out with the Autodyn code show good correlation with experimental results. The Hopkinson law is suggested to predict the blast wave’s parameters at large scale on the basis of small-scale experiments and simulations. This paper was based on work that was presented at the 20th International Colloquium on the Dynamics of Explosions and Reactive Systems, Montreal, Canada, July 31–August 5, 2005.     

Variation in the wave resistance of an amphibian air-cushion vehicle moving over a broken-ice field

The nonstationary rectilinear motion of an amphibian air-cushion vehicle (AACV) on a water surface covered with finely broken ice is considered for various modes of velocity variation. The influence of the water depth, flotation parameters, and mode of motion on the wave resistance of the vehicle is analyzed. Maneuvering methods for increasing or decreasing the wave resistance of AACVs are proposed. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 1, pp. 97–102, January–February, 2007.     

On the types and number of plane waves in hypoelastic materials

General principles are formulated for modeling the elastic deformation of materials and analyzing plane waves in nonlinearly elastic materials such as hyperelastic, hypoelastic, and those governed by the general law of elasticity. The results of studying the propagation of plane waves in hypoelastic materials are further outlined. The influence of initial stresses and initial velocities on the types and number of plane waves is studied. Wave effects characteristic of hypoelastic materials are predicted theoretically. One of such effects is blocking of certain types of plane waves by initial stresses __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 11, pp. 96–107, November 2005.     

Anti-miss-shot control device for selective stone disintegration in extracorporeal shock wave lithotripsy

A new device to prevent erroneously focused shock waves to the renal parenchyma during extracorporeal shock wave lithotripsy (ESWL) has been developed; an anti-miss-shot control device (AMCD) and experiments have been conducted to evaluate its effectiveness. For shock wave generation and stone localization, piezoceramic elements (PSE) and ultrasound localization, respectively were used. After stone localization, probing ultrasounds (PU) were emmitted from the PSE towards the focal region and the reflected sound levels (RSL) were monitored by the PSE which also functioned as a microphone. A direct hit by the PU to the stone or a miss was judged from the RSL, i.e. a high RSL indicates a direct hit and a low RSL indicates a miss. Shock waves were generated only when the RSL exceeded the level which indicated a direct hit. The experimental results showed that the injury to the renal parenchyma was decreased by using the AMCD. Clinical application of the AMCD is expected to increase the safety of ESWL.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1990.     

界面动力学研究近况

界面动力学主要包括界面波动力界面动态断裂两人部分，本文评述了其主要研究课题的最新进展，并在此基础上展望了其发展趋势，指出界面模型研究、界面无损检测、界面动态损伤与破坏机理、界面动态断裂韧性及弹塑性面裂纹动态扩展等是当前最关心且急待解决的问题。     

压-剪复合应力波作用下材料动态断裂韧性研究

提出亚微秒单脉冲应力波载荷作用下Ⅱ型裂纹的平板冲击实验技术 .加载率为dK dt～ 10 8MPa·m1 2 ·s-1.实验中由锰铜应力片和弹性波理论分别测定和计算了压应力 ;通过微观分析确定了动态裂纹的平均扩展长度 ;引进等效应力强度因子 ,用动态断裂理论确定了 6 0 #钢的动态断裂韧性KⅠd和KⅡd ;建立了亚微秒冲击载荷作用下确定材料动态断裂韧性的方法     

Evolution of a fast flame behind an induction zone

It has been shown that pressure waves can have a large effect on the burning rate of flames. In this paper, the evolution of convection-driven fast flame, which is acoustically linked to a shock wave via an induction zone, is examined in detail. It is found that there is positive feedback mechanism and the asymptotic model breaks down as blow up occurs. Comparison is made between the case of a piston driving a shock wave into a combustible atmosphere with these studies of a shock wave passing through an existing premixed flame. Received 4 August 1995 / Accepted 20 March 1996