http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Description of reversed yielding in thin hollow discs subject to external pressure
Sergei E. Alexandrov,Alexander R. Pirumov,Yeau-Ren Jeng 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.4
This paper presents an elastic/plastic model that neglects strain hardening during loading, but accounts for the Bauschinger effect. These mathematical features of the model represent reasonably well the actual behavior of several materials such as high strength steels. Previous attempts to describe the behavior of this kind of materials have been restricted to a class of boundary value problems in which the state of stress in the plastic region is completely controlled by the yield stress in tension or torsion. In particular, the yield stress is supposed to be constant during loading and the forward plastic strain reduces the yield stress to be used to describe reversed yielding. The new model generalizes this approach on plane stress problems assuming that the material obeys the von Mises yield criterion during loading. Then, the model is adopted to describe reversed yielding in thin hollow discs subject to external pressure.
Plane strain bending of a bimetallic sheet at large strains
Sergei E. Alexandrov,Nguyen D. Kien,Dinh V. Manh,Fedor V. Grechnikov 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.4
This paper deals with the pure bending of incompressible elastic perfectly plastic two-layer sheets under plane strain conditions at large strains. Each layer is classified by its yield stress, shear modulus of elasticity and its initial percentage thickness in relation to the whole sheet. The solution found is semianalytic. In particular, a numerical technique is only necessary to solve transcendental equations. The general solution is cumbersome because different analytic expressions for the radial and circumferential stresses should be adopted in different regions of the whole sheet. In particular, there are several alternative ways a plastic region (or plastic regions) can propagate. However, for any given set of material and process parameters the solution to the problem consists of a sequence of rather simple analytic expressions connected by transcendental equations. The general solution is illustrated by a simple example.
Effects of thickness variations on the thermal elastoplastic behavior of annular discs
Wang, Yun-Che,Alexandrov, Sergei,Jeng, Yeau-Ren Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.6
Metallic annular discs with their outer boundary fully constrained are studied with newly derived semi-analytical solutions for the effects of thickness variations under thermal loading and unloading. The plane stress and axisymmetric assumptions were adopted, and the thickness of the disk depends on the radius hyperbolically with an exponent n. Furthermore, it is assumed that the stress state is two dimensional and temperature is uniform in the domain. The solutions include the elastic, elastic-plastic and plastic-collapse behavior, depending on the values of temperature. The von Mises type yield criterion is adopted in this work. The material properties, Young's modulus, yield stress and thermal expansion coefficient, are assumed temperature dependent, while the Poisson's ratio is assumed to be temperature independent. It is found that for any n values, if the normalized hole radius a greater than 0.6, the normalized temperature difference between the elastically reversible temperature and plastic collapse temperature is a monotonically decreasing function of inner radius. For small holes, the n values have strong effects on the normalized temperature difference. Furthermore, it is shown that thickness variations may have stronger effects on the strain distributions when temperature-dependent material properties are considered.
Effects of thickness variations on the thermal elastoplastic behavior of annular discs
Yun-Che Wang,Sergei Alexandrov,Yeau-Ren Jeng 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.6
Metallic annular discs with their outer boundary fully constrained are studied with newly derived semi-analytical solutions for the effects of thickness variations under thermal loading and unloading. The plane stress and axisymmetric assumptions were adopted, and the thickness of the disk depends on the radius hyperbolically with an exponent n. Furthermore, it is assumed that the stress state is two dimensional and temperature is uniform in the domain. The solutions include the elastic, elastic-plastic and plasticcollapse behavior, depending on the values of temperature. The von Mises type yield criterion is adopted in this work. The material properties, Young’s modulus, yield stress and thermal expansion coefficient, are assumed temperature dependent, while the Poisson’s ratio is assumed to be temperature independent. It is found that for any n values, if the normalized hole radius a greater than 0.6, the normalized temperature difference between the elastically reversible temperature and plastic collapse temperature is a monotonically decreasing function of inner radius. For small holes, the n values have strong effects on the normalized temperature difference. Furthermore, it is shown that thickness variations may have stronger effects on the strain distributions when temperature-dependent material properties are considered.
Gaoshen Cai,Lihui Lang,Kangning Liu,Sergei Alexandrov,Dongxing Zhang,Xiying Yang,Chan Guo 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.2
Confirmation of material properties is an important research area for determining metals deformation behavior. In order to research the effect of flow stress calculation on aluminum alloy sheet deformation behavior,warm sheet bulging test was carried out to obtain bulging height - pressure curves with different bulging heightsand diameters in this study. Based on the bulging parts profile data measured by three coordinate measuringmachine, the least square circle fitting radius were fitted. Existing theoretical models for radius of curvatureand thickness were compared and best models were selected to obtain more accurate stress - strain curves bycalculating the bulging flow stress. Combination model was used to calculate the bulging height - pressurecurves obtained by bulging test and the stress-strain curves with different temperatures and pressure rates wereobtained. A monotonous increasing function was resulted which is of great significance in the area of formabilityand deformation behavior of warm sheet hydroforming.
RESEARCH OF DIFFERENT PROCESSES FOR FORMING FIBER METAL LAMINATES
Dmitrii Chernikov,Yaroslav Erisov,Ilia Petrov,Sergei Alexandrov,Lihui Lang 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.Supp
The paper presents the results of forming rifts in five-layer fiber reinforced metal polymer laminates by electromagnetic forming. During the experimental studies the discharge energy of the electro-magnetic machine was varied in such a way as to achieve different depths of the rift. Samples obtained by electro-magnetic forming were compared with control samples obtained by forming using a rubber pad under static loading. The strain state of the samples was analyzed using an digital image correlation system Vic-3D. The experimental research of fiber reinforced metal laminates forming under the influence of pulse magnetic field has shown the possibility of formability increasing due to change of strain state: the rift zone is dominated by compressive circumferential strains, rather than tensile radial strains as during conventional rubber pad forming.