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Transactions of Tianjin University 2008年第B10期14卷 476-482页

作者： Bratov Vladimir petrov yuri InstituteofProblemsofMechanicalEngineering 199178St.-PetersburgRussia St.-PetersburgStateUniversity 198504St.-PetersburgRussia

A problem for a central crack in a plate subjected to plane strain conditions is investigated. Mode I crack loading is created by a dynamic pressure pulse applied at a large distance from the crack. It was found that for a certain combination of amplitude and duration of the pulse applied, the energy transmitted to the sample has a strongly marked minimum, meaning that with the pulse amplitude or duration moving away from the optimal values, minimum energy required for initiation of crack growth increases rapidly. The results obtained indicate a possibility to optimise energy consumption of different industrial processes connected with fracture. Much could be gained in, for example, drilling or rock pounding where energy input accounts for the largest part of the process cost. Presumably further investigation of the effect observed can make it possible to predict optimal energy saving parameters, i.e. frequency and amplitude of impacts, for industrial devices, e.g. bores, grinding machines, and hence significantly reduce the process cost. The pre- diction can be given based on the parameters of the media fractured （material parameters, prevalent crack length and orientation, etc.）.

关键词： fracture energy saving incubation time fracture criterion

Transient near tip fields in crack dynamics

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Science China(Physics,Mechanics & Astronomy) 2011年第7期54卷 1309-1318页

作者： BRATOV Vladimir petrov yuri UTKIN Alexander Institute of Problems of Mechanical Engineering Russian Academy of SciencesSt.-Petersburg 199178Russia St.-Petersburg State University St.-Petersburg 198504Russia

Transient effects of stress-strain fields in the vicinity of a stationary crack tip under high rate loads are *** analytical solutions to near tip stresses are compared to fields prescribed by leading terms(one or several) of Williams asymptotic *** of load application mode,time(or,which is the same,distance from a crack tip) and Poisson's ratio on this discrepancy is extensively *** effects connected with crack tip propagation speed are also *** inconsistencies between real(or received in numerical solutions of state *** element computations) crack tip fields and stress intensity factor(SIF) singular field observed by numerous researchers are *** scope of problems where SIF field can be used for correct prediction of dynamic stress-strain fields in the crack tip region is *** to correctly approximate fields that are not SIF dominated,accounting additional terms of Williams expansion,is studied.

关键词： transient crack tip fields dynamic fracture high-rate loads asymptotic expansions

Incubation time approach in rock fracture dynamics

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Science China(Physics,Mechanics & Astronomy) 2012年第1期55卷 78-85页

作者： SMIRNOV V petrov yuri V BRATOV V St.-Petersburg State Transport University 198103 St.-Petersburg Russia St.-Petersburg State University 198504 St.-Petersburg Russia Institute of Problems of Mechanical Engineering Russian Academy of Sciences 199178 St.-Petersburg Russia

The paper is summarizing latest results connected with application of the incubation time approach to problems of dynamic fracture of rock materials. Incubation time based fracture criteria for intact media and media with cracks are discussed. Available experimental data on high rate fracture of different rock materials and incubation time based fracture criteria are used in order to evaluate critical parameters of causing fracture in these materials. Previously discovered possibility to optimize (minimize) energy input for fracture is discussed in connection to industrial rock fracture processes. It is shown that optimal value of momentum associated with critical load in order to initialize fracture in rock media does strongly depend on the incubation time and the impact duration. Existence of optimal load shapes minimizing momentum for a single fracturing impact or a sequence of periodic fracturing impacts is demonstrated.

关键词： incubation time dynamic fracture rocks dynamic strength fracture toughness crack resistance energy and momentum input fracture process optimization

The effect of toroidal field on the rotating magnetic field current drive in rotamak plasmas

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Chinese Physics B 2007年第11期16卷 3443-3450页

作者：钟方川 Huang Tian Sen petrov yuri^b Department of Applied Physics College of SciencesDonghua UniversityShanghai200051China Prairie View A&M University Prairie View.Texas 77446.USA

A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field （RMF）. The driven current can reverse the original equilibrium field and generate a field-reversed-configuration. In a conventional rotamak, a toroidal field （TF） is not necessary for the RMF to drive plasma current, but it was found that the present of an additional TF can influence the RMF current drive. In this paper the effect of TF on the RMF current drive in a rotamak are investigated in some detail. The experimental results show that addition of TF increases the RMF driven current greatly and enhances the RMF penetration dramatically. Without TF, the RMF can only penetrate into plasma in the edge region. When a TF is added, the RMF can reach almost the whole plasma region. This is an optimal strength of toroidal magnetic field for getting maximum plasma current when Bv and radio frequency generator power are fixed. Besides driving current, the RMF generates high harmonic fields in rotamak plasma. The effect of TF on the harmonic field spectra are also reported.

关键词： rotamak rotating magnetic field toroidal field

Threshold characteristics of short-pulsed loads combined with the ultrasound field causing dynamic delamination of adhesive joints

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Theoretical & Applied Mechanics Letters 2018年第1期8卷 28-31页

作者： Nikolai Gorbushin yuri petrov Ya-Pu Zhao Yin Zhang St.-Petersburg State University St.-Petersburg 198504Russia Institute of Problems of Mechanical Engineering St.-Petersburg 199178Russia State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing 100080China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

In the present work, we analyse the delamination problem under the combined dynamic load. We show the effect of background harmonic vibrations on critical amplitudes of the principal force pulse. The effect is demonstrated on the simple model of a string on an elastic foundation and the fracture phenomenon is predicted by the incubation time criterion. The results state the possibility of considerable decrease in threshold amplitude by a proper choice of the frequency of a background excitation.

关键词： Dynamic fracture Incubation time criterion Delamination

Dynamic failure of dry and fully saturated limestone samples based on incubation time concept

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 125-134页

作者： yuri V. petrov Ivan V. Smirnov Grigory A. Volkov Andrei K. Abramian Anatoliy M. Bragov Stanislav N. Verichev Saint Petersburg University Universitetskaya nab. 7-9 Saint Petersburg 199034 Russia Institute of Problems of Mechanical Engineering Russian Academy of Sciences Bolshoj pr. 61 V.O. Saint Petersburg 199178 Russia Lobachevsky State University of Nizhni Novgorod Prospekt Gagarina 23 Nizhny Novgorod 603950 Russia Allseas Engineering B.V. Poortweg 12 Delft 2612 PA The Netherlands

This paper outlines the results of experimental study of the dynamic rock failure based on the comparison of dry and saturated limestone samples obtained during the dynamic compression and split tests. The tests were performed using the Kolsky method and its modifications for dynamic splitting. The mechanical data(e.g. strength, time and energy characteristics) of this material at high strain rates are obtained. It is shown that these characteristics are sensitive to the strain rate. A unified interpretation of these rate effects, based on the structuraletemporal approach, is hereby presented. It is demonstrated that the temporal dependence of the dynamic compressive and split tensile strengths of dry and saturated limestone samples can be predicted by the incubation time criterion. Previously discovered possibilities to optimize(minimize) the energy input for the failure process is discussed in connection with industrial rock failure processes. It is shown that the optimal energy input value associated with critical load, which is required to initialize failure in the rock media, strongly depends on the incubation time and the impact duration. The optimal load shapes, which minimize the momentum for a single failure impact, are demonstrated. Through this investigation, a possible approach to reduce the specific energy required for rock cutting by means of high-frequency vibrations is also discussed.

关键词： Dynamic strength Incubation time criterion Split Hopkinson pressure bar(SHPB) test Tensile strength Compressive strength Water-saturated limestone Vibration-assisted rock cutting

INCUBATION TIME CONCEPT IN PROBLEMS OF PULSED STRENGTH OF CONTINUA:FRACTURE,CAVITATION,AND ELECTRICAL BREAKDOWN

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INCUBATION TIME CONCEPT IN PROBLEMS OF PULSED STRENGTH OF CO...

The Study of Different Structuring Techniques for Creation of Non-Evaporable Getters

祝贺郑哲敏先生八十华诞应用力学报告会

作者： yuri V.petrov St.-Petersburg State University NIIMMUniversitetsky Prospect28PetrodvoretsSt.-Petersburg199178Russia

Experiments on the dynamic fracture of solids,hquids,conductors,andinsulators that is caused by fast intense actions of environment or directed energy fluxesreveal a number of effects indicating a fundamental difference between the fast dynamicrupture(breakdown)of materials and a similar process under slow quasistatic *** example,one of the basic problems in testing the dynamic-strength properties of ma-terials is associated with the dependence of the limiting characteristics on the duration,amplitude,and growth rate of an external action,as well as on a number of other *** a critical value is a constant for a material in the static case,experimentallydetermined critical characteristics in dynamics are strongly unstable,and as a result,their behavior becomes *** indicated(and some other)features of thebehavior of materials subjected to pulsed actions are common for a number of seeminglyquite different paysical processes,such as dynamic fracture(starting cracks and scab-bing),cavitation in liquids,and electrical breakdown in *** this paper,we analyzeexamples illustrating typical dynamic effects inherent in these *** propose aunified interpretation for the fracture of solids and liquids and electrical breakdown ininsulators using the structural-time approach[1,2]based on the concept of the fractureincubation time.

关键词： pulsed strength incubation time spalling fracture cavitation in fluids electrical breakdown

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Materials Sciences and Applications 2013年第8期4卷 57-61页

作者： Anton Boyko Dahir Gaev Sergei Timoshenkov yuri Chaplygin Vladimir petrov Kabardino-Balkarian State University Moscow Russia National Research University of Electronic Technology Moscow Russia Research Institute of Advanced Materials and Technology Moscow Russia

The results of observation of different structuring techniques of thin metal layers applied in micro system technologies are presented. The Ti V getter films formed by magnetron sputtering have been explored using scanning electron and atomic-force microscopy, Brunauer-Emmett-Teller method, thermogravimetric analysis and fractal geometry. The film sorption capacity for hydrogen given by thermogravimetry was of 7.7 m3·Pa·g-1. To estimate the effective surface area, the fractal geometry tools were used and the calculated value of the specific surface area was about 155 m2/m3. The second object under investigation was a structure composed of micro- and mesoporous silicon and copper layer deposited electrochemically on the pore walls. Porous silicon when coupled with a reactive metal or alloy is expected to be an effective getter for micro system techniques. The use of porous silicon and specific conditions of depositions allows to form the structure of complex fractal type with a specific surface area of 167 m2/cm3.

关键词： Non-Evaporable Getters MEMS Structuring Magnetron Sputtering Electrodeposition Porous Silicon

THE LASER TOMOGRAPHICAL METHOD USINGMINIMUM OF PROJECTION FOR BIOLOGICAL OBJECT STRUCTURE STUDY

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激光生物学报 1995年第3期 679-684页

作者： yuri N. Kulchin Oleg B. Vitrik Oleg V. Kiricheiko yuri S.petrov Oleg T. Kamenev(Far Eastern State Technical University 690600,Vladivostok,Pushkinskaya 10,Department of Physics,Russia)

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关键词： Tomography Nondistructive study of biological objects Measuring schema.