共查询到20条相似文献,搜索用时 12 毫秒
1.
2.
V. A. Zakharov A. I. Ul’yanov E. S. Gorkunov V. V. Velichko 《Russian Journal of Nondestructive Testing》2013,49(5):260-269
Dependences of the coercive force and mechanical stresses on cyclic tensile in the region of elastic deformation of steel samples with various carbon contents (Armco iron, 3, 8) are investigated. It is shown that the dependence of the coercive force on cyclic elastic tensile deformation is reversible for well-annealed samples. The dependence for plastically deformed steels has a hysteresis loop that is significantly determined by the carbon content and increases with an increasing degree of plastic deformation. It is assumed that the hysteresis of the coercive force as a function of elastic cyclic tensile deformations in plastically deformed carbon steels is caused generally by the appearance “free” carbon atoms, i.e., those not bound in carbide phases, which act as interstitial impurity atoms in the lattice of α-iron. 相似文献
3.
Effective elastic constants of two-dimensional cellular materials with deep and thick cell walls 总被引:1,自引:0,他引:1
In order to analyse the elastic constants of cellular materials with deep and thick cell walls, finite element analysis using two kinds of unit cell approach (stiffness matrix method and compliance matrix method) is performed which is applicable to any orthotropic cellular materials. Comparison between results from the FEA, the theories presented in this paper and experiments of previous investigators indicate that the elastic constants of cellular materials with thick cell walls depend not only on the relative density but also on the joint stiffening effect. Approximate formulae under generalised plane strain conditions are also presented for the purpose of obtaining the effective elastic constants for cellular materials with deep and thick cell walls. A satisfactory agreement was found with experimental results obtained on a deep and thick cellular material. The results indicate that the previous models in which the wall of cellular materials is treated as a simple beam are not adequate to evaluate the effective elastic constants of cellular materials with deep and thick cell walls. In addition, considerable attention needs for the measurement of effective Young's modulus of square cellular materials in the two soft directions because it is strongly affected by misalignment errors. 相似文献
4.
Measurement of material elastic constants for limited-size samples by ultrasonic method is described and validated. Based on acoustic microscope technology, the material elastic constants are determined by longitudinal wave and leak surface wave velocities simultaneously measured by developed ultrasonic system with a line-focus PVDF transducer. In this paper, the elastic constants of limited-size Cr2O3 doping on 0.2 PZN–0.8 PZT piezoelectric ceramic wafer sample are determined and the measurement errors are analyzed. The experimental results show this ultrasonic system can be used for measurement of material elastic constants for limited-size samples with high measurement precision, and the relative errors for Poisson’s ratio and Young’s module measurements are, respectively, less than 1% and 3%. It can satisfy the requirement of engineering and science research. Furthermore, it is suitable to measure elastic constants of both isotropic and anisotropic materials by ultrasonic method with help of developed ultrasonic system. 相似文献
5.
K. V. Kostin T. P. Tsar’kova A. P. Nichipuruk Ya. G. Smorodinskii 《Russian Journal of Nondestructive Testing》2011,47(9):593-602
The changes in the shape and characteristics of the major and asymmetric hysteresis loops of low-carbon pipe steels under
the action of elastic and plastic tensile strains were studied. The hysteresis loop segments that experienced the most considerable
transformations under the tension of a material were determined. The possibilities of the inspection of tensile strains by
the coercive return magnetization and the magnetic field corresponding to a fixed magnetization on the descending branch of
a hysteresis loop were shown. 相似文献
6.
In this study, the validity of the Eshelby-type model for predicting the effective Young’s modulus and in-plane Poisson’s
ratio of the 2-dimensional perforated plate has been investigated in terms of the porosity size and its arrangement. The predicted
results by the Eshelbytype model are compared with those by finite element analysis. Whenever the ratio of the porosity size
to the specimen size becomes smaller than 0.07, the effective elastic constants predicted by finite element analysis are convergent
regardless of the arrangement of the porosities. Under these conditions, the effective Young’s moduli of the perforated plate
can be predicted within the accuracy of 5% by the Eshelby-type model, which overestimates and underestimates the effective
Poisson’s ratios by 10% and 6% for the plates with periodically and non-periodically arranged porosities, respectively. 相似文献
7.
8.
To minimise the uncertainty in pressure measured with a pressure balance its pressure distortion coefficient should be determined with a sufficiently low uncertainty. The elastic constants of piston–cylinder assembly (PCA) materials are used in the calculation of the pressure distortion coefficient and thus are one of the uncertainty sources. In this work, the resonant ultrasound spectroscopy (RUS) is applied to determine the elastic constants of PCAs’ tungsten carbide (WC) materials. A validation of the RUS technique has been carried out by measurements on rectangular parallelepiped and cylindrical samples of fused quartz, steel D22S (30CrNiMo8) and a well-known WC material. The WC materials which are used in new 7 MPa absolute pressure balances aimed at a redetermination of the Boltzmann constant have been studied. The measurements demonstrate RUS to be suitable for determining the Young modulus (E) and the Poisson ratio (μ) with standard uncertainties as low as 0.03% and 0.05%, respectively. They show variations in E and μ of up to 4% and 2%, respectively, for different batches of nominally the same material. In a few cases, even for samples cut out of the same WC piece, material inhomogeneities have been observed in both RUS and the density measurements with variations in E and μ of up to 0.8% and 0.5%, respectively. 相似文献
9.
小试件材料弹性常数超声测量系统的研制 总被引:2,自引:0,他引:2
本文针对小试件块体纳米材料力学性能测试的特殊需求,设计开发了一套小试件材料弹性常数超声精密测量系统。系统由线聚焦PVDF探头、四轴精密运动平台、NI PXI总线嵌入式控制器、超声脉冲产生/接收仪以及数字记忆示波器组成。系统基于声学显微镜技术,利用同时测定纵波和漏表面波波速来表征材料的弹性常数等,既适用于各向同性材料,又适用于各向异性材料。试验结果表明本测量系统工作良好,能够满足试验要求,为进一步评价小试件纳米材料制备工艺和表征纳米材料的力学性能奠定了基础。 相似文献
10.
The research activities of the calculation of the elastic constants of metal are mainly focused on the elastic constants of crystal at the micro level. To the calculation of the macroscopic elastic constants of metal, although molecular dynamics method and quasicontinuum method can be used, but there are shortcomings in them, such as a large amount of computation and that the spatial scale of the study model is limited. Therefore, with a pure metal thin plate composed of a single layer of microscopic particles as research object, a new mechanical model is established after the interactions between microscopic particles of the thin plate are applied on the continuum mechanics model of the thin plate. According to this model, the calculation formulas for the microscopic elastic constants, which are the elastic constants of any triangle region in the model, are obtained. After the concept of the ideal micro structure is presented, the calculation formulas for the macroscopic elastic constants, the elastic modulus and the Poisson’s ratio of pure metal are obtained, where the Poisson’s ratio is the constant that is equal to 1?3. As an example, the elastic constants and the elastic modulus of pure copper are solved, where c11 is 175.811 GPa, c12 is 58.604 GPa, c33 is 58.604 GPa and E is 156.277 GPa, the rationality and the correctness of the model are verified. The model presented fully embodies the discreteness of the microstructure of solid, is a development to the continuum model, and is more suitable to reality, more simplified and more new to the study of the macroscopic elastic constants of pure metal. 相似文献
11.
In this study, a new model to predict the effective elastic constants of composites with spherical fillers is proposed. The
original Eshelby model is extended to a finite filler volume fraction without using Mori-Tanaka’s mean field approach. When
single filler is embedded in the matrix, the effective elastic constants of the composite are computed. The composite is in
turn considered as a new matrix, where new single filler is again embedded in the matrix. The predicted results by the present
model with a series of embedding procedures are compared with those by Mori-Tanaka, self-consistent, and generalized self-consistent
models. It is revealed through parametric studies such as stiffness ratio of the filler to the matrix and filler volume fraction
that the present model gives more accurate predictions than Mori-Tanaka model without using the complicated numerical scheme
used in self-consistent and generalized self-consistent models. 相似文献
12.
H. R. Javidrad Sina Salemi 《The International Journal of Advanced Manufacturing Technology》2020,107(11):4597-4607
The nature of additive manufacturing (AM) processes prescribes direction-dependent properties of the final parts. The degree of material anisotropy is high 相似文献
13.
14.
V. F. Novikov V. A. Zakharov A. I. Ul’yanov S. V. Sorokina M. E. Kudryashov 《Russian Journal of Nondestructive Testing》2010,46(7):520-526
The influence of biaxial elastic tension-compression and tension-tension deformation on the coercive force and remanent magnetization
of Cτ3 steel and 09Γ2C pipe steel cross-shaped specimens is studied. It is shown that coercive force grows monotonically with
increasing load in the direction of compression under elastic tension-compression deformation and almost does not change under
elastic tension-tension deformation. The local remanent magnetization decreases for all the considered types of biaxial elastic
deformation. The possibility of using these methods for the evaluation of the stressed state of complexly deformed carbon
steel products is discussed. 相似文献
15.
16.
17.
18.
19.
《Wear》1987,116(1):19-24
The structure and wear resistance of steels treated in a gas sulphonitriding atmosphere, which contained NH3 and 0.006% CS2 in endothermically derived propane carrier gas, was investigated.The sulphonitrided layers offer favourable wear resistance relative to untreated steels. 相似文献
20.
T. K. Kandavel Ramaswamy Chandramouli 《The International Journal of Advanced Manufacturing Technology》2010,50(1-4):53-59
The present investigation pertains to the study of the mechanical properties and fracture behavior of sinter-forged low alloy steels containing copper (Cu) and molybdenum (Mo) as alloying elements. Elemental powders of atomized iron, graphite, molybdenum, and copper were mixed in suitable proportions using a ball mill, compacted in a 1,000 kN hydraulic press using suitable cylindrical die–punch combination and sintered at 1,000 ± 10°C in a muffle furnace for a period of 120 min in order to yield the alloy compositions (by weight) such as Fe–0.5% C, Fe–0.5% C–1% Cu, Fe–0.5% C–2% Cu, Fe–0.5% C–1% Mo, and Fe–0.5% C–2% Mo. The sintered cylindrical preforms were then subjected to hot upset forging to near theoretical density and subsequently machined off to standard size in order to carry out the mechanical tests such as hardness, tensile, and impact tests. Addition of Cu and Mo to the plain carbon steel has been observed to enhance the tensile strength as well as hardness of the sinter-forged alloys. The presence of Mo carbides in the microstructure of the alloys further reinforces this observation. The impact strength of this alloy has been observed to be reduced considerably due to the addition of the alloying elements. 相似文献