理论模型在高质量、无缺陷铸坯生产中的应用

尽管连续铸钢技术已经在全世界广泛、成功地应用，然而通过现存所选择的工艺和设计参数来生产高质量产品还有一些障碍。近年来，通过冶金工作者的不断努力，取得了一些突破性成就。     

特殊地形电力架空线的导线计算

电力架空线路是一项经常遇到的设计内容。当架空线路经过地形复杂的山区布线时,往往在悬挂导线的杆塔之间出现大高差或孤立档。用常规的平抛物线法计算导线的应力弧垂等参数的结果,与实际数值相差较大,这时需采用斜抛物线法来计算,本文对斜抛物线法的计算进行了探讨。     

浅谈混凝土的温度裂缝

经多年的施工监理实践,在查阅有关混凝土内部应力方面的专著后,对混凝土温度裂缝产生的原因、现场混凝土温度的控制和预防混凝土温度裂缝的措施进行阐述。     

Assessment of Viscoplastic Properties of Titanium Alloys

The paper presents findings of the study of viscoplastic properties of several titanium alloys subjected to cyclic loading under complex stress state conditions. The applicability of elastic viscoplastic models to structural materials has been experimentally verified.__________Translated from Problemy Prochnosti, No. 3, pp. 37 – 44, May – June, 2005.     

An advanced numerical method for computing elastodynamic fracture parameters in functionally graded materials

A new meshless method for computing the dynamic stress intensity factors (SIFs) in continuously non-homogeneous solids under a transient dynamic load is presented. The method is based on the local boundary integral equation (LBIE) formulation and the moving least squares (MLS) approximation. The analyzed domain is divided into small subdomains, in which a weak solution is assumed to exist. Nodal points are randomly spread in the analyzed domain and each one is surrounded by a circle centered at the collocation point. The boundary-domain integral formulation with elastostatic fundamental solutions for homogeneous solids in Laplace-transformed domain is used to obtain the weak solution for subdomains. On the boundary of the subdomains, both the displacement and the traction vectors are unknown generally. If modified elastostatic fundamental solutions vanishing on the boundary of the subdomain are employed, the traction vector is eliminated from the local boundary integral equations for all interior nodal points. The spatial variation of the displacements is approximated by the MLS scheme.     

Evolution of internal stress and microstructure in Ti50Cu50 alloy films: influence of substrate temperature and composition

The growth stress of Ti₅₀Cu₅₀ alloy films on alumina substrates was measured in situ under ultrahigh vacuum conditions with a cantilever beam technique as a function of substrate temperature and variation of copper concentration. The growth stress of films deposited at low temperature is interpreted to indicate the growth of amorphous respectively nanocrystalline films. At substrate temperatures above 300 °C, a novel tensile stress contribution is interpreted to be due to the formation of a preferentially oriented film of metastable copper vacancy superstructured γ-TiCu. Finally, at substrate temperatures above 365 °C, a polycrystalline γ-TiCu film is formed.Annealing of low-temperature alloy films gives rise to irreversible tensile stress changes indicating restructuring of the films. The stress change measured when annealing a superstructured γ-TiCu film is compressive and is assigned to the transformation of the metastable superstructure to polycrystalline γ-TiCu. The magnitude of this compressive stress contribution is strongly dependent on the copper concentration, i.e., copper vacancy concentration.     

Surface-directed spinodal decomposition in a stressed, two-dimensional, thin film

Two-dimensional simulations of the spinodal decomposition of self-stressed, binary thin films using a Cahn-Hilliard model are presented. Two different sets of mechanical boundary conditions are considered, and compositional strains for a cubic-anisotropic system under plane strain are treated. A composition-dependent interaction energy is assumed at the free surface. Numerical solution of the coupled Cahn-Hilliard and elastic equilibrium equations are obtained using an efficient nonlinear multigrid method. Results of simulations show that, for large enough compositional strain, surface-directed decomposition occurs at the traction-free surface, even when there is negligible surface interaction energy initially attracting one of the components. This decomposition is controlled by elasticity, and results in a local alignment of phases perpendicular to the free surface, in contrast to the parallel alignment produced by surface energy in stress-free systems.     

Plastic strain-controlled short crack growth and fatigue life

Constant plastic strain-controlled and constant stress-controlled tests were performed on smooth and lightly notched specimens machined from a massive forging of 42CrMo4 steel. Comparison of the fatigue life curves plotted as function of the plastic strain amplitude and stress amplitude shows a decisive role of plastic strain amplitude. Crack initiation and the kinetics of short crack growth were studied in constant plastic strain amplitude loading and the relation between the crack growth coefficient and plastic strain amplitude was established. This is equivalent to the Coffin–Manson law and shows that the Coffin–Manson law can be interpreted in terms of short crack growth.     

Fracture experiments on through wall cracked elbows under in-plane bending moment: Test results and theoretical/numerical analyses

Fracture assessment of pipe bends or elbows with postulated through wall crack is very essential for leak-before-break qualification of primary heat transport system piping of nuclear power plants. The methodology for fracture assessment of cracked elbows is still in developing stage. Any new development in theoretical aspect requires experimental validation. However, fracture test data on cracked elbows is not so abundant as straight pipes. The earlier experiments on cracked elbows were focused mainly on the determination of limit load. Other fracture parameters e.g. crack growth, crack initiation load or crack opening displacement were not reported in the open literature. Against this backdrop, a comprehensive experimental and theoretical program on component integrity has been initiated at Reactor Safety Division (RSD) of Bhabha Atomic Research Center (BARC), India. Under this program, a number of fracture tests have been carried out on elbows with through wall circumferential/axial cracks subjected to in-plane closing/opening bending moment. These test data are then thoroughly analysed numerically through non-linear finite element analyses, analytically through limit load comparison and also through comparison of crack initiation loads by finite element and R6 methods. These test data may be utilized in future for validation of new theoretical developments in the integrity assessment of through wall cracked elbows.