金属材料的强度与应力-应变关系的球压入测试方法

压入法获取材料单轴应力-应变关系和抗拉强度对服役结构完整性评价有重要的基础意义.假定材料均匀连续、各向同性、应力应变关系符合Hollomon律,基于能量等效假定,即代表性体积单元(representativevolume element, RVE)的vonMises等效和有效变形域内能量中值等效假定,本文提出了关联材料载荷、深度、球压头直径和Hollomon律的四参数半解析球压入(semi-analyticalspherical indentation,SSI)模型.通过球压入载荷-深度试验关系获得材料的应力-应变关系和抗拉强度.考虑压入过程中的损伤效应,针对金属材料提出了用于球压入测试的材料弹性模量修正模型.对11种延性金属材料完成了球压入试验,采用本文提出的球压入试验方法测到的弹性模量、应力-应变关系和抗拉强度与单轴拉伸试验结果吻合良好.      

EXAMPLES ARE GIVEN TO ILLUSTRATE THE UNIQUENESS LAW OF SOLUTIONS FOR PLANE PROBLEMS OF ELASTICITY

解的唯一性定理是用逆解法或半逆解法求解弹性力学问题的理论依据,在此用应力函数法、应力法、应力和函数法求解弹性力学平面问题,让学生切实、深入地理解解的唯一性定理的内在含义,丰富和扩大弹性力学的解题方法和应用范围。     

An axiomatics of geomechanics

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Noether's conservation laws of holonomic nonconservative dynamical systems in generalized mechanics

In the present paper, three kinds of forms for Noether's conservation laws of holonomic nonconservative dynamical systems in generalized mechanics are given. First Received Dec. 4, 1992     

非平衡性引起的对质量作用定律的偏离

在化学反应动力学中,质量作用定律占有重要的地位,通常认为,该定律仅适用于理想的反应体系,并假定,一旦反应在平衡条件下遵循质量作用定律,那么在非平衡条件下也应遵循该定律,但根据最近的研究结果,平衡条件下的理想反应体系,在非平衡条件下可能变成非理想体系,换言之,非平衡性可能引起非理想性,这表明,非平衡条件下的(基元)反应并不总是遵守质量作用定律,本文利用文献的一些结果,并结合1个具体反应模型,研究了山非平衡性引起对质量作用定律的偏离,结果表明,非平衡性本身对反应动力学规律有重要影响,对化学反应动力学的研究亦具有一定启发作用。     

An analysis on entrance region effect of the laminar radial flow between two parallel disks

In this paper, B. B. Golubef method^[1] is used for calculating the radial diffuse flow between two parallel disks for the first step. The momentum integral equation together with the energy integral equation is derived from the boundary layer momentum equation, and the expression of secondary approximation explicit function in which the channel length of entrance region varies with the boundary layer thickness can be obtained by using Picard iteration[2] in the solution of the energy integral equation. Therefore, this has made it possible to analyze directly and analytically the coefficients of the entrance region effect. In particular, when the outer diameter of disk is smaller than the entrance region length, the advantage of this method can be prominently manifest.Only because the energy integral equation is employed, the terms in the pressure loss coefficient can be independently derived theoretically. The computable value of the pressure loss coefficient presented in this paper is nearer to the testing value than that in ref. [3] when the entrance correction Reynolds number Re<100. Therefore the results in this paper within Re<100 are both reliable and simple.     

A new quadrilateral nonconforming model and its convergence

This paper presents a new quadrilateral nonconforming finite element. We deal with its convergence by using generalized patch test T error on stresses and displacements are obtained and numerical computations for plane elastic problems are given.     

The ring shells under gravitative loads

This paper gives Novozlov’s equation (ref. [1]) in a simple style of ring shells with equal thickness under the actions of gravitative loads. By means of Fourier series, the special solution of the equation is established. Using the results of the homogeneous solution in ref. [2], we find out the general solution of the problem, and derive the expressions of stress and displacement.Two examples are given as the application of the above results.     

Dynamic dislocations solution to elastoplastic moving cracks

In the range of micro-cosmic, an analogy between linear dislocation arrays and moving cracks is drawn, then elastoplastic moving crack problems are derived by superposition of distribution of dislocations. Various dynamical crack-opened-displacements are derived, which gives an elastoplastic stability criterion of moving cracks. In this paper, modes Ⅰ,Ⅱ,Ⅲ moving crack problems are discussed respectively.     

The existence of solutions in nonlinear elastodynamics

I.Intr0ductionIntheclassicalelasticity,thelinearconstitutivelawisassumed,wherethehyper-potentialisapositiveorsemi-positivedefinitequadraticform.Forsuchsystems,theexistence,uniquenessandrelativepr0pertiesofsolutionstostaticanddynamicproblemscanbefound[l'2'…