Yu. V. Petrov

Saint Petersburg State University | SPBU · Faculty of Mathematics and Mechanics

The synthesis of photothermal carbon/hydroxyapatite composites poses challenges due to the binding modes and relatively low photothermal conversion efficiency. To address these challenges, the calcium ions chelated by photothermal carbon dots (PTC-CDs) served as the calcium source for the synthesis of photothermal carbon dots chelated hydroxyapatit...

The bone-targeting mechanism of clinic bisphosphonate-type drugs, such as alendronate, risedronate, and ibandronate, relies on chelated calcium ions on the surface of the bone mineralized matrix for the treatment of osteoporosis. EGTA with aminocarboxyl chelating ligands can specifically chelate calcium ions. Inspired by the bone-targeting mechanis...

Peridynamic formulations of the mean stress and incubation time fracture models are discussed in the paper. Contemporary fracture simulations using the peridynamic theory often rely on critical bond stretch fracture criterion which is known to operate similar to energy-based fracture models. The energy-based fracture criteria—both in classical Grif...

The constitutive models at high loading rates are usually investigated by introducing additional and empirical rate-dependent components into classical models initially developed for quasi-static cases. In addition, the dynamic stress–strain curves of many materials are non-monotonic. The yield drop phenomenon can be observed in series of experimen...

Nanomaterials are widely used in different fields, such as microelectronics, industry, and nanocomposites, and they can exhibit unstable deformation behaviour depending on the strain rates. Under strain rates of 10−4–10−1 s−1, the deformation of nanomaterials, unlike the quasi-static deformation of micromaterials, is characterized by the presence o...

The temporal nature of static and dynamic deformation of fibre metal laminates is discussed here. The aim of the study is to verify the proposed innovate model using layered composites. The modified relaxation model is based on the earlier formulated plasticity relaxation model for homogeneous materials. The proposed relaxation model makes it possi...

To predict of appearance and disappearance of yield drop effects with regard to different dynamics, temperatures or other factors, the wide spectrum of the initial plastic stage of stress–strain diagrams for homogeneous materials is considered. Compared with unchanged quasi-static stress–strain diagrams, the dynamic changes in stress–strain diagram...

The aim of the present paper is to investigate the effect of stabilisation of the hysteresis loop under hard loading on steel C45E. C45E, which is widely used for the manufacture of shafts and characterised by its superior strength. Here, we experimentally investigate the phenomenon of plastic deformation stabilisation at rigid loading, depending o...

An analytical investigation of a fundamental dynamic fracture effect observed in samples with a crack under shock-wave pulse load is provided. Particular attention is paid to the phenomenon of delayed fracture. The effect can be described in the following way: the fracture in the crack tip vicinity can possibly take place after the local stresses r...

Despite significant research on spallation, there are still unexplored gaps such as the spall fracture delay. In this case, fracture occurs not at the growth stage of tensile stress in a spall section but at the stage of stress stabilization or reduction. However, no attention was paid to this effect. In this paper, we present an experimental and t...

Dynamic fracture of a one-dimensional chain of identical linear oscillators (masses connected by springs) is regarded in the work. The considered system consists of arbitrary but finite number of links and the first mass is supposed to be fixed. Two types of load are discussed: free oscillations of the initially uniformly stretched chain and loadin...

The problem of pulse-induced and acoustic cavitation of degassed water is considered within the framework of the incubation time approach. The analytical model to describe a dependency of the cavitation threshold on the pulse duration is developed and applied to experimental data in order to evaluate the main model parameter as the incubation time....

In this short communication application of the incubation time fracture criterion (ITFC) for analysis of crack initiation under short pulse loading conditions is discussed. It is shown that the ITFC can be used to predict and investigate one of the key effects of the dynamic fracture – the fracture delay. The fracture delay phenomenon manifests its...

The randomized method of Sign-Perturbed Sums (SPS) is applied within the framework of the incubation time approach to evaluate the dynamic strength of ice. The experimental data of [Carney et al., 2006; Wu and Prakash, 2015; Saletti et al., 2019] is analysed in order to estimate strength parameters of ice and describe the observed strain-rate sensi...

The multistage irreversible deformation in the case of tension of multilayer composites is studied from viewpoint of a dynamics as a function of structural-temporal characteristics and static mechanical characteristics. Experimental stress–strain curves of fibre metal laminates under static and dynamic loading are analyzed on the basis of extended...

The influence of background ultrasonic field on the ultimate dynamic strength of adhesive joints is studied using fracture mechanics analysis. Winkler foundation-type models are applied to describe the cohesion zone, and the incubation time fracture criterion is used. The challenging task is to study whether relatively weak ultrasound is able to de...

The paper presents the numerically evaluated dependence of the stress intensity factor (SIF) on crack velocity (KI-a˙ dependence) in Homalite-100 specimens subjected to pulse loading. Experiments on crack propagation (Ravi-Chandar and Knauss in Int J Fract 25:247–262, 1984. https://doi.org/10.1007/BF00963460; Int J Fract 26:65–80, 1984. https://doi...

Recent experimental studies on spall fracture show that the impact parameters can lead to insta-bilities in the strain rate dependence of the dynamic strength of the material. Here we consider the effect of the dynamic impact parameters on the time dependences of the material ultimate stress. Numerical modeling of spall fracture is conducted for ul...

Dynamic brittle fracture under high-rate loading conditions is analyzed. A new numerical algorithm based on peridynamic approach and structural-temporal model of fracture is used to predict the start of a crack in glassy polymer samples. The results of calculations are compared with available experimental data.

Overhang provides a simple but effective way of coupling (sub)structures, which has been widely adopted in the applications of optomechanics, electromechanics, mass sensing resonators, etc. Despite its simplicity, an overhanging structure demonstrates rich and complex dynamics such as mode splitting, localization and eigenfrequency veering. When an...

Dependencies and parameters describing the crack propagation process can often exhibit unstable behavior which is not predicted by classic fracture mechanics. Here such phenomena as the crack velocity oscillations and floating stress intensity factor (SIF) values for the initiation of a pulse loaded crack can be mentioned. This paper considers SIF...

In the present work the problem of dynamic crack initiation in the brittle solid body was studied using the non-classical approaches of continuum mechanics: peridynamics and incubation time fracture model. For this purpose, structural and incubation time criteria were formulated as criteria of the bond failure. These approaches consider the stress...

The paper proposes a model that allows us to determine the fracture location in case of multiple spalling. The incubation time criterion was used to predict fracture in material. Modeling was performed for spall fracture performed on concrete rods. Comparison of the calculation results with experimental data was carried out which showed the coincid...

The adaptability of steel 45 to low-cycle deformation from 100 to 1000 cycles at different constant strain amplitudes, characterised by the effect of plastic-strain stabilisation, is considered. In this study, the proposed structural–temporal model of cyclic deformation simultaneously predicted the stress-strain dependence and the effect of plastic...

Исследованы вопросы динамического хрупкого разрушения в условиях высокоскоростного нагружения. Новая численная схема на основе перидинамического подхода и структурно-временной модели разрушения применяется для прогнозирования старта трещины в образцах из стеклообразного полимерного материала. Приведено сравнение результатов расчетов с экспериментал...

Eigenfrequency loci veering, which indicates strong mode coupling and sometimes mode localization, is a much sought-after property in the applications of mass sensing and opto/electromechanics. A weak physical coupling is the mechanism responsible for the eigenfrequency loci veering and overhang is a widely used structure to realize such mechanism....

The strength of the adhesion joint under the combined vibrational-pulsed loading is considered. Beam and membrane models on elastic foundation is applied to simulate behavior of adhesion zone. The incubation time criterion is used to determine the threshold parameters of a load required to adhesive zone fracture. The solution of the differential eq...

The work presents experimental and numerical results on dynamic fracture of PMMA plates subjected to impact loading. The experimental tests were conducted using steel cylinder-shaped projectile accelerated using a gas gun. In order to evaluate performance of the tested specimens, residual impactor velocity was assessed using high-speed photography...

Dynamic fracture of a one-dimensional chain of identical linear oscillators (masses connected by springs) is considered in the work. The system is supposed to consist of arbitrary but finite number of links and the first mass is supposed to be fixed. Two loading conditions are discussed: free oscillations of an initially statically prestressed chai...

Dependence of stress intensity factor (SIF) on crack velocity (KI−ȧ dependence) in Homalite-100 specimens subjected to pulse loading was numerically studied. The numerical scheme is based on finite element method and incubation time fracture criterion. Experimental results from works by Ravi-Chandar and Knauss (1984a,b,c) were used. Experimentally...

Dynamic fracture effects such as fracture delay and dependence of the material strength on the loading rate are known from multiple experiments on crack initiation and spallation. Classic linear oscillator (mass-spring system) is considered and critical spring stretch fracture condition is added. Due to relative simplicity of the model and availabi...

The interaction of a constant cross-section rod with an elastic environment under dynamic loading is considered. The directly proportional to the displacement resistance forces impacted on the rod. Elastic and viscoelastic one-dimensional models describing longitudinal vibrations occurring in a rod located in the environment are developed. Numerica...

Responses of the aluminum multilayer composite to dynamic loading are described by the relaxation model of plasticity. Relations between the rate sensitivity of the multilayer composite, parameters of the dynamic loading and the strain rate sensitivity of its components are established. It is shown that estimates of the rate sensitivity turned out...

Ultrasonically assisted drilling (UAD) is a non-traditional machining process that employs the vibration of a cutting tool. It offers a better alternative and solution to the challenges of drilling marble using conventional drilling (CD) methods. Machining-induced damage in marble results in the rejection of parts. A significant force reduction is...

The responses of an aluminum multilayer composite to dynamic loading are described using the relaxation model of plasticity. The relations between the strain-rate sensitivity of a multilayer composite, the dynamic-loading parameters, and the strain-rate sensitivity of its components are established. The estimates of the strain-rate sensitivity are...

An increase in the velocities of automobile and aerospace transport and, simultaneously, the necessary of decreasing their masses increase the requirements to the operating reliability of used materials and constructions. In this case, the operation of a material under dynamic impact loads remains in nonnormative ranges. This work presents a compre...

Plastic deformation of metals and polymethylmethacrylate under the action of dynamic load is analyzed based on the relaxation model of plastic deformation. The parameters of the relaxation model of plasticity are invariant with respect to the deformation history which allows, within a unified approach, obtaining any set of deformation curves, both...

Experimental and theoretical data for the strength performance of 1230 aluminum alloy under tension in the quasi-static and dynamic ranges of loading parameters are presented. Using the structural temporal approach and the sign-perturbed sums algorithm, the feasibility of raising the strain rate of a specimen by decreasing its geometrical size has...

The study of fracture of thin aluminum rings due to shock loading generated by magnetic-pulse method was performed. This method provides experimental results on dynamic fracture under conditions of pure tension for a wide range of loading conditions. To simulate rapture of the ring samples a structural-temporal fracture criterion was applied. This...

Experimental dependences of the strength of frozen sandy soil on strain rate are analyzed using a structural–temporal approach. Results of dynamic uniaxial compression tests at a temperature of −18°C and strain rates of 400 to 2600 s⁻¹ of frozen sandy soil specimens of two types with an ice mass fraction of 10 and 18% measured at room temperature a...

Available results of laboratory investigations of the dynamic strength of various sandstone types are analyzed with the use of the incubation time criterion in both compression and tension cases. Based on this approach, a theoretical relation is derived, which describes the increase in the sample fracture stress under dynamic conditions. Incubation...

Test results are presented for an additive material prepared of acrylonitrile-butadiene-styrene on a 3D printer. Dynamic tension experiments have been carried out using a tower-type drop hammer with an accelerator. Data obtained from different specimens demonstrate that high-strain-rate tensile experiments are feasible if the working part of the sp...

In the paper, a new phenomenological interpretation of some of the principal temporal effects of high-rate plastic deformation of metals from a united viewpoint is represented. A comparative analysis of some of the well-known dynamic plastic deformation models is given. Influence of strain rate on the stress-strain relation in a wide range of strai...

Dynamic crack propagation due to quasistatic loading in PMMA plates with a notch is considered. Both experimental data and results of numerical simulations are presented. The crack tip position was registered using slit-scan photography. Numerical simulations were performed using the finite element method and the incubation time fracture criterion....

Some problems of strength and stability of thin constructions with defects and inclusions, which are of vital importance for nano- and microtechnology, are investigated. The attention is paid to the estimation of the number of defects influencing the capacity for work of nanosized plated and shells. The influence of surface effect is taken into acc...

Application of split Hopkinson pressure bar technique allows to provide material strength measurements in the case of dynamic loadings. Numerous experiments under different rocks have demonstrated significant rising of dynamic strength with increasing of stress or strain rate. For the goal to analyse extreme properties of sandstone materials under...

A dynamic tensile strength of rocks and concrete is studied in a wide range of strain rates using a structural-temporal approach. An idea of a material's fracture incubation time, taken as a scale dependent material constant and as a primary measure of the reaction of materials subjected to dynamic loading, was applied to explain the instability of...

The strength and resistance of the Ti–6Al–4V titanium alloy to solid particle erosion have been studied in as-delivered state and after the equal-channel angular pressing. The ultrafine-grained material and the initial material have been tested for dynamic tension using an Instron drop tower testing machine and an aerodynamic setup for erosion test...

The processes of ultrasonically-assisted drilling (UAD) and the dynamic tests on split Hopkinson pressure bar (SHPB), fracture in which is implemented at various structural-scale levels, are considered. The simulation of UAD based on the Hertz contact problem and the structural−time criterion is presented. The problem of using the value of the frac...

The evolution of a structural–temporal integral criterion of yielding is reported for the description of the dynamic deformation of metals. The values of characteristic relaxation times, considered as the constants of the material, are shown to be suitable for the description of dynamic effects upon the nanomaterial deformation in a wide range of l...

This paper considers experimental and theoretical study of a compressor blade steel (EI-961 grade), subjected to solid particle erosion. Material samples were cut from the first stage compressor blades and then tested in a modified wind tunnel, capable of mixing abrasive media into an accelerated airflow. Velocity of the abrasive stream vas varied...

In this work, the results on solid particle erosion of an ultrafine-grained Grade 5 titanium alloy, which was produced using high-pressure torsion (HPT) technique, are presented. In order to assess influence of the HPT treatment on material’s behavior in erosive conditions, special experimental procedures were developed. The ultrafine-grained (UFG)...

Different rock material dynamic laboratory tests have been analyzed with the help of incubation time criteria approach. As a result of made calculations incubation times for such rocks like granite, marble, limestone, sandstone and traverline have been estimated. This parameter according to criteria theory rule material behavior under high rate loa...

This paper analyzes the effect of the time-dependent shape of a load pulse on the spall strength of materials. Within the framework of a classical one-dimensional scheme, triangular pulses with signal rise and decay portions and with no signal rise portions considered. Calculation results for the threshold characteristics of fracture for rail steel...

The behavior of the yield strength of steel and a number of aluminum alloys is investigated in a wide range of strain rates, based on the incubation time criterion of yield and the empirical models of Johnson-Cook and Cowper-Symonds. In this paper, expressions for the parameters of the empirical models are derived through the characteristics of the...

At the present time, the methods for the measurement and prediction of the dynamic strength of materials are complicated and unstandardized. An experimental data processing method based on the incubation time criterion is considered. Only a finite number of measurements containing random errors and limited statistical information are usually availa...

The model of a string on an elastic foundation is applied to study adhesive zone delamination induced by combined vibrational - pulsed actions. The incubation time criterion is utilized in order to predict a critical delamination condition. The influence of the background ultrasonic field onto the value of threshold stress-pulse amplitudes is demon...

The fraction of the ductile component of the fracture surface after solid particle erosion for different materials was investigated. The minimum amount of viscous fracture on the fracture surface was observed in aluminum samples with the FCC lattice and very high stacking fault energy, and the maximum was found in copper samples with the same FCC l...

The study presents the results of investigation for different aluminum alloys. Small samples of these materials were subjected to static and dynamic tension. A numerical analysis using an incubation time fracture criterion has been carried out. For each material a set of fixed constants were obtained that allows determine the dependencies of the ten...

Results of dynamic tests of pipe steel of strength category of 650 MPa on dynamic strength, fluidity and fracture toughness are presented. The stress-strain curves for shock tension and the dependence of the ultimate destruction characteristics of materials on the strain rate and temperature are constructed. To obtain the parameters of dynamic frac...

A modeling of various effects of high-rate plastic deformation of metals on the basis of the relaxation model of plasticity is considered. It is shown that the relaxation model of plasticity is an effective tool to describe both temporal dependencies of the yield stress and a well-known yield stress drop effect on the deformation curve from the uni...

Principal effects of dynamic instability of the fracture process are investigated. Particularly an issue of a dependence of stress intensity factor (K) on crack velocity (v) is discussed. Uniqueness, related to the given material, and even existence of this dependence has been a matter of discussion among researchers, since contradicting experiment...

This paper is devoted to investigations of copper ring samples loaded under high-strain-rate by magnetic pulse method. Three loading schemes are used to achieve strain rate up to 1000000 1/s. The temporal dependence of strength in wide range of time is presented. Microstructure investigations of fracture surface and cross-section under these loadin...

Methods of measurement and prediction of materials dynamic strength are complicated and not standardized. Usually dynamic tests are labour-consuming and each assay demands a lot of time in contrast to static experiments. The way of experimental data treatment based on incubation time criterion and randomized approach of sign-perturbed sums is consi...

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 criter...

On the basis of modification of the relaxation model of plasticity developed previously for the case of single loading, a new model of cyclic deformation is formulated. It is shown that the introduction of only one constant time parameter dependent on the material structure makes it possible to compose a simple calculation scheme of accumulation of...

Testing results for Ti–6Al–4V ultrafine-grained titanium alloy obtained via intensive plastic torsional deformation (IPTD) are presented. To estimate the effect of IPTD treatment on the behavior of this material under erosion conditions, special experimental techniques were developed. The ultrafine-grained alloy was tested alongside with the tradit...

The dependence of the critical load on the degree of nonuniformity of the stress field is considered on the example of polymethylmethacrylate beams and plates with a round hole or a sharp notch. It is proposed to use nonlocal criteria for brittle fracture to describe the behavior of a nonuniformly stressed material. Among the criteria considered, t...

The paper presents several results of structural fracture macromechanics used to study the integrity of continuum under impulse loading conditions. The dynamic problem on a semi-infinite steady-state crack of longitudinal shear is considered. Exact analytical expressions for the stress tensor and displacement vector components on the crack line are...

The kinetics of fracture and deformation of the standard aluminum alloy AD1 and a similar alloy subjected to severe plastic deformation by high-pressure torsion under conditions of high-speed erosion has been investigated. It has been shown that, with an increase in the loading rate, the fraction of the brittle component on the fracture surface of...