Dynamic and fractal properties of SP-28 steel under high-speed loading conditions

Барахтин, Б. К.; Meshcheryakov, Yu. I.; Savenkov, G. G.

doi:10.1134/1.1259174

Cited by 5 publications

(7 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mechanical parameters of the tested materials have been analyzed previously [4][5][6]. The data [4-6] of the electron-microscopic scanning of the tested samples show that, for the majority of steel grades (40Kh, 45KhMFBA, 12Kh18N10T, Sp.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, models has been developed that take into account the discrete nature of a deformable medium, which is treated as a dissipative system, whose evolutions leads to the occurrence of fractal structures capable of self-similar propagation resulting in global fracture upon reaching some critical conditions [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…The scale Δl can be determined from relation (2) (for this, it is first necessary to find the fractal dimension D, for example, using the method of vertical sections [4]) or to specify its concrete value because the dimension depends weakly on the chosen measurement scale unit (a geometrical unit with a constant multiplicity or a physical unit with multiplicity due to structural characteristic scales). The most suitable value Δl = 0.1 μm, which is the intermediate one between the microlevel and mesolevel I.…”

mentioning

confidence: 99%

“…There are a number of models describing various features of material behavior under dynamic (spall) fracture conditions. Wide use has been made of models that include only two fracture stages (microlevel and macrolevel) or employ only statistical methods for describing the initiation and development of defects [1].Recently, models has been developed that take into account the discrete nature of a deformable medium, which is treated as a dissipative system, whose evolutions leads to the occurrence of fractal structures capable of self-similar propagation resulting in global fracture upon reaching some critical conditions [2][3][4][5].The purpose of the present work is to establish relations among the strength t fr , the spall strength σ fr of the material, and the fractal parameters of the fracture surface formed during shock-induced spall fracture.Experimental Technique. Disks-shaped targets 52 mm in diameter and 5-10 mm thick made of steels of various classes were loaded by a flat impactor using a pneumatic gun at velocities V 0 = 200-650 m/sec.…”

mentioning

confidence: 99%

“…28 steel samples (E = 204 GPa, ν = 0.28, ρ 0 = 7.8 · 10 3 kg/m 3 , and C 0 = 4450 m/sec) for various values of the initial impact velocity V 0 . The experimental data are taken from [4,21]; in all cases, the maximum scale of the increase is η = 5 · 10 3 [4] and the fractal dimension of the fracture surface is D S = 1 + D, γ = 1.5 · 10 −3 .…”

mentioning

confidence: 99%

See 4 more Smart Citations

Relationship between spall characteristics and the dimension of fractal fracture structures

Барахтин

Savenkov²

2009

J Appl Mech Tech Phy

Self Cite

View full text Add to dashboard Cite

The effect of the fractality of a fracture surface and spall contour on the characteristics [fracture time (strength) and spall strength] of the loaded material is studied. It is shown that an increase in the fractal dimensions of the spall contour leads to an increase in the material strength parameter in the tensile wave and spall strength, whereas an increase in the fractal dimension of the fracture surface leads to a decrease in the spall strength. As an example, the spall strength is calculated taking into account the fractality of the fracture surface for Sp. 28 steel. Introduction.As is known, the dynamic (in particular, spall) fracture of materials is a multiphase kinetic process based on the polyscale evolution of internal material defects. At each scale level, the nature and duration of elementary events of structural changes are different and interrelated. In addition, the initiation and development of defects at different stages is possible, i.e., the formation of macrodefects can be accompanied by the initiation of submicrodefects, their coalescence with the formation of microdefects, etc. In this case, the indicated processes influence each other. From the aforesaid, it follows that constructing a mathematical multilevel model of dynamic (spall) fracture taking into account the multifactor nature of the process (description of each level, determination of the relations between the physical processes at each level, and determination of the influence of the processes occurring at all levels on the processes occurring at a chosen level) is a difficult problem. There are a number of models describing various features of material behavior under dynamic (spall) fracture conditions. Wide use has been made of models that include only two fracture stages (microlevel and macrolevel) or employ only statistical methods for describing the initiation and development of defects [1].Recently, models has been developed that take into account the discrete nature of a deformable medium, which is treated as a dissipative system, whose evolutions leads to the occurrence of fractal structures capable of self-similar propagation resulting in global fracture upon reaching some critical conditions [2][3][4][5].The purpose of the present work is to establish relations among the strength t fr , the spall strength σ fr of the material, and the fractal parameters of the fracture surface formed during shock-induced spall fracture.Experimental Technique. Disks-shaped targets 52 mm in diameter and 5-10 mm thick made of steels of various classes were loaded by a flat impactor using a pneumatic gun at velocities V 0 = 200-650 m/sec.The tested targets were studied with a SEM 535 scanning electron microscope. The fractal dimensions of the spall contour and the size distribution of shear and spall regions (defects) were determined by digitization and statistical processing of electron photomicrographs of vertical sections of the fracture surface of the targets at magnifications over a wide range (from 10 to 5 · 10 3 ).Experimental Resu...

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Relationship between spall characteristics and the dimension of fractal fracture structures

Барахтин

Savenkov²

2009

J Appl Mech Tech Phy

Self Cite

View full text Add to dashboard Cite

show abstract

Structural Transformation in Two-Component Medium

Indeitsev

Skubov

Vavilov

2017

30th International Symposium on Shock Waves 2

View full text Add to dashboard Cite

Critical Stresses in Spalling and Dynamic Rupture of Metals

Savenkov¹

2005

J Appl Mech Tech Phys

Self Cite

View full text Add to dashboard Cite

Results of dynamic rupture tests of a series of metals obtained using a composite Hopkinson bar and shock-wave loading of plane specimens are described. It is shown that the actual rupture strength at a strain rate of 5 · 10 3 sec −1 is very close to the spall strength at higher strain rates. Results of testing the same metals using a composite Hopkinson bar within a temperature range of 20-350 • C are given.Despite numerous papers that have been published on the strength of materials under shock-wave loading and certain progress in general understanding of the physical processes that occur therein, the problems of correct determination of the spall strength and comparability of data obtained with results of other types of dynamic and quasi-static tests are still unsolved.The main results, which are believed to be most reliable, on determining the spall strength are obtained by methods based on continuous recording of the free-surface velocity of a specimen (target) under uniaxial strain conditions. In the acoustic approach, the spall strength of an ideal material (amplitude of tensile stresses σ tens acting in the spall section inside the specimen) is [1]where ρ 0 is the initial density of the material, c 0 is the volume velocity of sound, V 0 is the maximum free-surface velocity, V m is the free-surface velocity at the first minimum of the dependence V (t), and t is the time.In the case of materials with explicit manifestation of elastoplastic properties in both incident and reflected waves, a correction factor associated with the determination of the difference in velocities ∆V = V 0 −V m is introduced into formula (1) to take into account that the unloading part of the incident compressive pulse with a velocity ≈ c 0 catches up with the leading part of the spalling pulse that propagates with a velocity of the longitudinal elastic wave c lead : σ 0 = 0.5ρ 0 c 0 (∆V + δV ).(2)Various types of relations for δV can be found in [1][2][3]. The existing models for spall fracture are based on the stage nature of the spalling process. Most authors consider two to four stages: "explosion-like" formation of numerous single micro-and mesocracks, combination of them into groups (finite clusters), growth and merging of clusters into one macrocrack (infinite cluster) extending over the entire specimen, and, finally, total failure of the specimen into fragments (so-called formation of a spalling "plate"). All the stages are considered in the zone of the extension-wave action; nevertheless, even in the case of a low-intensity shock wave, there is a possibility of formation of micro-and mesodefects with dimensions l 1,2 10 −6 m, which can be parallel or perpendicular to the shock-wave front (l 1 and l 2 are the lengths of the perpendicular and parallel defects, respectively). The reason is that, as was shown in a number of papers (see, e.g., [4] and the literature cited therein), the motion of micro-and mesoflows of particles of the material under shock-wave loading possesses Krasnoznamenets Research-and-Production Enterprise,...

show abstract

Dynamic and fractal properties of SP-28 steel under high-speed loading conditions

Cited by 5 publications

References 2 publications

Relationship between spall characteristics and the dimension of fractal fracture structures

Relationship between spall characteristics and the dimension of fractal fracture structures

Structural Transformation in Two-Component Medium

Critical Stresses in Spalling and Dynamic Rupture of Metals

Contact Info

Product

Resources

About