Deformation and failure mechanism in AISI 4340 steel under ballistic impact

Deformation and failure mechanism in quench-hardened AISI 4340 steel under ballistic impact is investigated. The influence of microstructure on damage evolution is also evaluated. Strain localization and shear failure along adiabatic shear bands are the dominant deformation and failure mechanisms. The time and critical strain for the commencement of strain localization is influenced by strain rate and microstructure. The microstructure of the steel sample also influenced the type of adiabatic shear bands formed during impact. Failure mechanism involves nucleation of micro-voids, which clusters to form bigger pores. Extremely fine micro-cracks are initiated adjacent to the pores and in shear flow direction along the shear bands. These micro-cracks become interconnected and grow to macro-cracks, which cause fracture of some of the investigated cylindrical steel samples under impact. The susceptibility of the adiabatic shear bands to cracking increases with decreasing tempering temperature of the steel.     

Deformation and failure under impact loading. model of a thermoelastoplastic medium

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 116–123, September–October, 1990.     

On rubber disks under rotation or axisymmetric stretching

The governing equations for a class of axisymmetric problems under large elastic deformation, concerned with a circular rubber disk with body force as well as non-uniform initial thickness, are formulated in terms of two coupled first-order ordinary differential equations with explicit derivatives. The following two problems subjected to different boundary conditions are solved: (a) Rotating disks with uniform initial thickness (b) Circular disks with non-uniform initial thickness under axisymmetric stretching at the outer boundary. In problem (b), the rubber disk whose initial thickness contour is h₀ = crⁿ (where c and n are any constants), or whose final thickness is a constant, is considered. Highly elastic materials with a Mooney strain-energy function are used for numerical calculations.     

Deformation of glued beams under harmonic loading

The dynamic deformation of glued beams with a thin adhesive interlayer under harmonic loading is studied. The virtual-work principle is used. The system of ordinary differential equations for the amplitudes in the approximations in coordinate functions is derived and solved. The proposed approach allows determining the stresses and strains at an arbitrary point of the beam, especially in the adhesive interlayer. Numerical results are presented     

Elastoplastic analysis of nonlinearly hardening variable thickness annular disks under external pressure

Based on von Mises’ yield criterion, deformation theory of plasticity and Swift’s hardening law, elasto-plastic deformation of variable thickness annular disks subjected to external pressure is studied. A nonlinear shooting method using Newton’s iterations with numerically approximated tangent is designed for the solution of the problem. Considering a thickness profile in the form of a general parabolic function, the condition of occurrence of plastic deformation at the inner and outer edges of the annular disk is investigated. A critical disk profile is determined and the corresponding elastic–plastic stresses as well as the residual stress distribution upon removal of the applied pressure are computed and discussed.     

Elastic Deformation of Materials under Distributed Shear Loading

In this work, the deformation of material under localised tangential loading has been investigated. An analytical expression to predict deformation and strain patterns under tangential loading over a rectangular patch on a surface is validated against experiential tests using surface displacement measurement and finite element modelling. The predicted force- displacement data and displacement/strain patterns show close agreement with experimental results a rubber test material and FE results. The ranges of specimen geometries that minimise the boundary effects have been determined.     

Seepage Consolidation under Plane Deformation of Elastic Half-Space

The process of seepage consolidation of elastic saturated half-space under the action of an arbitrary normal surface load is investigated in the case of plane deformation. The fluid and skeleton grains are assumed to be incompressible. A new mathematical model of consolidation is proposed with the use of the compatibility equation. Analytic dependences for the sum of effective normal stresses and fluid pressure are found on the basis of this model. The total normal stresses are explicitly expressed in terms of these dependences.     

Deformation Characteristics of Laminar Composites under Nonlinear Strains

It is shown that the type of governing relations in a composite can change, namely, a laminar composite formed by layers of physically linear materials under nonlinear strains should be described by nonlinear Hooke's law. Local stresses can be not proportional to elastic constants of the layers under nonlinear strains.     

转动的圆盘

对于应力沿厚度变化的转动圆盘, 仍考虑为平面应力问题进行了分析.     

固体的冲击拉伸碎裂

固体材料在冲击拉伸载荷作用下常常会断裂成多个碎片(碎片化),固体材料碎片化的物理机制是多点损伤同时在固体中成核和发展,导致固体多处破坏。自 Mott 对固体的动态碎裂问题进行了开创性研究后,几十年来,对固体动态碎裂机制的研究一直是应用物理学、力学、航天和兵器工程等领域共同关心的重要课题。本文介绍了在冲击拉伸载荷作用下固体的动态碎裂研究的发展历史,给出相关的理论分析、实验研究和数值模拟的研究进展,特别针对现有的各种关于碎片尺度、碎片分布、以及碎片化物理机制的理论模型进行了较详尽的阐述和讨论,最后指出现有实验和理论研究中仍然存在的关键科学问题及进一步的研究展望。     

Analysis of an Anisotropic Finite Wedge under Antiplane Deformation

The antiplane deformation of an anisotropic wedge with finite radius is considered in this paper within the classical linear theory of elasticity. The traction-free condition is imposed on the circular segment of the wedge. Three different cases of boundary conditions on the radial edges are considered, which are: traction-displacement, displacement-displacement and traction-traction. The solution to the governing differential equation of the problem is accomplished in the complex plane by relating the displacement field to a complex function. Several complex transformations are defined on this complex function and its first and second derivatives to formulate the problem in each of the three cases of the problem corresponding to the radial boundary conditions, separately. These transformations are then related to integral transforms which are complex analogies to the standard finite Mellin transforms of the first and second kinds. Closed form expressions are obtained for the displacement and stress fields in the entire domain. In all cases, explicit expressions for the strength of singularity are derived. These expressions show the dependence of the order of stress singularity on the wedge angle and material constants. In the displacement-displacement case, depending upon the applied displacement, a new type of stress singularity has been observed at the wedge apex. This revised version was published online in August 2006 with corrections to the Cover Date.     

Elastoplastic Deformation of a Compound Disk under Impulsive Loading

The small elastoplastic deformation theory and the finite-element method are used to analyze the behavior of a compound disk under axisymmetric impulsive loading. Numerical results are presented, which describe the development of plastic deformation, the effect of hardening and the duration of the loading impulse on the oscillatory elastoplastic deformation of the disk__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 4, pp. 94–99, April 2005.     

Fragmentations of solids under impact tension

固体材料在冲击拉伸载荷作用下常常会断裂成多个碎片(碎片化),固体材料碎片化的物理机制是多点损伤同时在固体中成核和发展,导致固体多处破坏.自Mott对固体的动态碎裂问题进行了开创性研究后,几十年来,对固体动态碎裂机制的研究一直是应用物理学、力学、航天和兵器工程等领域共同关心的重要课题.本文介绍了在冲击拉伸载荷作用下固体的动态碎裂研究的发展历史,给出相关的理论分析、实验研究和数值模拟的研究进展,特别针对现有的各种关于碎片尺度、碎片分布、以及碎片化物理机制的理论模型进行了较详尽的阐述和讨论,最后指出现有实验和理论研究中仍然存在的关键科学问题及进一步的研究展望.     

Thermal Failure of Polymeric Structural Elements under Monoharmonic Deformation

Thermal-failure problems are formulated for three-dimensional, thin-walled structural elements made of passive and piezoactive materials and subjected to monoharmonic deformation. Methods are described for calculation of critical electric and mechanical, quasistatic and dynamic monoharmonic loads and for analysis of postcritical behavior. The influence of various factors on the critical load is analyzed. Theoretical and experimental data are compared and found to be in good agreement, which is indicative of the reliability of the models used to describe the thermal failure of polymeric structural elements