Dynamic uniaxial tension and compression curves of copper and alloy AMg6

Bolshakov, A. P.; Novikov, S. A.; Синицын, В. А.

doi:10.1007/bf00768612

Cited by 13 publications

(12 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By increasing the penetration velocity in the experiments, we obtained the value V * ≈ 500 m/sec and, hence (for R t Y * ) Y * ≈ 320 MPa. This value of Y * is in good agreement with the value of the yield point in compression [11] for the obtained deformation velocity approximately equal to V * /L 0 . It is assumed that the hydrodynamic mode begins when the impactor velocity exceeds the velocity of hydrodynamic transition V ht , which is given by the relation (1) for V − U = C p [1].…”

supporting

confidence: 82%

Penetration of a copper rod into a sandy target

Kaminskii

Копытов

Mogilev

et al. 2010

J Appl Mech Tech Phy

View full text Add to dashboard Cite

This paper presents the results of experimental and theoretical studies of high-velocity penetration of cylindrical copper rods into sand. The hydrodynamic Alekseevskii-Tate theory is modified to determine the penetration depth and wear velocity of the material of the rod penetrating into soil target in the plastic and hydrodynamic stages of penetration. The case where the target material is significantly less strong than the rod (impactor) material is considered.Introduction. The high-velocity penetration of long rods (impactors) into dense media includes two stages of deformation [1-3]: 1) plastic stage, where the decrease in the length of the solid part of the impactor occurs at a rate equal to the velocity of the longitudinal plastic wave C p ; 2) hydrodynamic stage, where the wear velocity of the impactor V − U exceeds the velocity of the longitudinal wave of plastic deformation (V is the velocity of the undeformed tail part of the impactor and U is the penetration velocity).The hydrodynamic stage of high-velocity penetration is adequately described by a modified hydrodynamic Alekseevskii-Tate theory (MHT) [4-8] based on the results of experimental studies of penetration of metal rods into high-strength (mainly metal) targets. However, high-velocity penetration of metal rods into porous soft soil media has been studied insufficiently (see, for example, [9]).One of the key parameters characterizing the high-velocity interaction of an impactor with a target in the hydrodynamic stage of penetration is the coefficient of relative penetration K = h/ΔL [h is the current penetration depth and ΔL is the shortening (wear) of the impactor]. The coefficient K allows one to predict the total wear depth of the impactor in the hydrodynamic stage in the case of stationary penetration. Stationarity is provided by a great (not less than sevenfold) elongation of the impactor (see, for example, [7]). According to the Alekseevskii-Tate model, the quantity K depends on the penetration velocity V 0 . As V 0 increases, the value of K decreases, approaching the asymptotic value given by the well-known Lavrent'ev formula [10] for the case of an ideal incompressible fluid:The objectives of the present work was to experimentally determine the critical velocity V * at which plastic deformation begins, the velocities of hydrodynamic transition V ht , and the velocities of a longitudinal plastic wave in a copper rod during its penetration into sand C p , and to improve the MHT to describe high-velocity penetration taking into account two stages of deformation of the impactor in the case where the target material is significantly less strong than the impactor material.1. Results of Experiments. The cylindrical copper impactors fired from ballistic facilities into soil had diameter d = 1 cm, length L 0 = 8.22 cm, and mass m = 57.5 g. The impactors were made of M1 copper alloy with a conventional yield point in compression σ 0.2 ≈ 290 MPa [11] and density ρ p = 8.9 g/cm 3 . Experimental data were obtained by x-ray photography of the penetra...

show abstract

supporting

confidence: 82%

Penetration of a copper rod into a sandy target

Kaminskii

Копытов

Mogilev

et al. 2010

J Appl Mech Tech Phy

View full text Add to dashboard Cite

show abstract

“…2. The satisfactory agreement of the FEM data (solid curve), experimental strain rates & e = × 2 10 3 sec -1 (circles) [3], and Hopkinson-approximated data (small squares) is indicative of the adequate accuracy of the method used and the correct selection of geometrical parameters. If we have a relationship between s and e calculated using a compressional wave, then it is possible to individualize the mechanical Bodner-Partom parameters K 0 and m 1 , which are responsible for the initial yield stress and the rate of isotropic hardening.…”

mentioning

confidence: 87%

“…To individualize the model parameters, we will use curves of static and rapid loading [2,3]. Since no data are available on the Bauschinger effect under high strain rate deformation, we will use the results of static tests from [8].…”

mentioning

confidence: 99%

Using a split Hopkinson bar to specify the parameters of thermomechanical models of flow under high strain rate deformation

Сенченков

Andrushko

2008

Int Appl Mech

View full text Add to dashboard Cite

By way of numerical simulation, a method is developed to determine the parameters of the thermomechanical Bodner-Partom model of flow under high strain rate deformation using a split Hopkinson bar. The classical method is generalized in two directions. To evaluate the kinematic hardening parameters, the wave reflected from the free end of the bar is used. The thermomechanical parameters that are responsible for the stored energy of cold work are calculated from measurements of temperature changes in the specimen Keywords: split Hopkinson bar, Bodner-Partom model, Baushinger effect, temperature change, finite-element method, stored energy of cold workIntroduction. The coupling of mechanical and thermal fields is of theoretical and applied importance. While in service, many structural elements of modern engineering are subjected to cyclic or impulsive loads, which may induce inelastic residual strains and temperature changes, either reversible (thermoelastic) or irreversible (dissipative) [12,13,30]. Monotonic quasistatic, high strain rate, and very high strain rate loading may give rise to local regions of large inelastic strains and high temperature (thermal shear bands) [22,23,25,28], which may lead to failure.On the other hand, thermal effects of deformation represent a number of prominent aspects of material behavior, which are either difficult or impossible to analyze within the framework of purely mechanical models. Among them are stored energy of cold work, dissipation of mechanical energy as heat, etc. A conceptual factor is that a characteristic variable of an adiabatic process is temperature, which can be measured experimentally. Thermal effects also carry information useful for diagnostics and study of damage kinetics, structural transformations, etc. [18,26].The reliability of data obtained in studying nonstationary thermomechanically coupled dynamic processes in high strain rate (10 2 -10 3 sec -1 ) and very high strain rate (10 3 -10 6 sec -1 ) deformation is strongly dependent on the choice and individualization of constitutive equations. A criterion for choosing a model should be its capability of describing viscosity, dependence of the yield stress on the strain rate, hardening, thermal effects, damage, etc.A split Hopkinson bar is widely used to test dynamic properties [15,17,19,20,24]. The equipment developed in [21] to measure temperature in a sample through which a wave propagates allows us to study the effects of thermomechanical coupling.The thermodynamically consistent Bodner-Partom model [9][10][11] was used in [27] to determine, for AMg-6 aluminum alloy, the portion of the inelastic work that does not dissipate as heat and accumulates by hardening ("cold work"). The results obtained there were used for numerical simulation of thermal (temperature) effects in a disk under impulsive radial loading. An analysis revealed that a chief task in studying such effects is to individualize the parameters of a thermodynamic model of flow under high strain rate loading.In the present paper, we carry o...

show abstract

“…The material of the disk is chosen to be AMg-6 aluminum alloy. An analysis of the experimental loading diagrams for AMg-6 [3] yields the following dynamic parameters of the isothermal Bodner-Partom model, incorporating the effects of isotropic and kinematic hardening:…”

mentioning

confidence: 99%

Nonstationary waves in an inelastic disk under impulsive radial loading

2005

View full text Add to dashboard Cite

Nonstationary axisymetric waves in a disk excited by an impulsive radial load are analyzed numerically. The nonlinear deformation of the material is described by the Bodner-Partom model. The model parameters are derived from experimental data for samples subjected to tension followed by compression over a wide range of strain rates. The temporal and spatial characteristics of the wave process are studied. The influence of hardening on wave focusing and residual strain distribution is examined Keywords: nonstationary waves, physically nonlinear material, disk, impulsive loading, finite-element methodIntroduction. Many structural members in modern technology are cylindrical bodies that, while in service, experience impulsive loads, which induce inelastic residual strains. Strength evaluation of such structures calls for stress-strain analysis methods that would allow for the rheological behavior of the material, the geometry of the body, and nonstationary loads acting on it.Analysis of residual stress-strain state (SSS) of bodies under impulsive loading is of considerable theoretical and practical interest [20,21]. These problems play a crucial role in the fatigue crack arresting techniques currently under development. They use an impulsive, explosion load with energy focused at the crack tip to induce compressive residual stresses and plastic strains [10].Research in this field is also motivated by the needs of explosion welding [5]; impulsive straightening of thin-walled structures, including welded ones [6,27]; surface hardening [15,22]; etc. In all these applications, the prime objective of calculations is to determine the appropriate process parameters. New technologies also require studying the influence of dynamic processes on the kinetics of microstructural transformations in materials [18, 28, etc].In studying nonstationary dynamic processes, reliable results can be obtained by accomplishing two basic tasks. One is to select and specify constitutive equations for fast (10 10

show abstract

Dynamic uniaxial tension and compression curves of copper and alloy AMg6

Cited by 13 publications

References 3 publications

Penetration of a copper rod into a sandy target

Penetration of a copper rod into a sandy target

Using a split Hopkinson bar to specify the parameters of thermomechanical models of flow under high strain rate deformation

Nonstationary waves in an inelastic disk under impulsive radial loading

Contact Info

Product

Resources

About