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71.
为获得离子型稀土矿体在非饱和-饱和状态下的强度特性,以江西龙南地区某离子型稀土矿为研究对象,利用GDS非饱和三轴仪对不同饱和度的重塑矿体开展常规三轴试验,研究发现:饱和度对矿体的应力-应变关系有显著影响,随着饱和度的增加,矿体的应力-应变关系由应变软化型逐渐转变为应变硬化型,破坏模式由脆性破坏转变为塑性破坏,抗剪强度呈非线性降低;饱和度的变化对矿体的内摩擦角影响不明显,对总黏聚力的影响很大,可认为饱和度变化对矿体强度的影响,主要是通过改变总黏聚力的大小来起作用的;通过线性回归分析,矿体总黏聚力与含水量呈半对数线性关系,总黏聚力与饱和度呈乘幂函数关系,并针对该离子型稀土矿提出与饱和度有关的总应力抗剪强度公式。 相似文献
72.
L.A. Alekseyeva 《Engineering Analysis with Boundary Elements》1998,22(4):327-331
The boundary value problem of elastodynamics is considered in cylindrical domains when acting boundary forces are moving with constant speed parallel to cylinder's axis. The fundamental solutions, boundary integral equations and integral representation of the solutions are constructed using distribution theory for three kinds of speed: subsonic, transonic and supersonic. 相似文献
73.
The theory for a fluid saturated linearly isotropic elastic matrix is still the basis for many geophysical applications, and commonly adopts Biot’s symmetric stress–strain laws for the matrix stress and fluid pressure. These involve a shear modulus and three elastic moduli governing the mixture and constituent compressions, in contrast to four compression moduli if Biot’s invalid potential energy argument is not applied. We now show that an energy argument applied to undrained loading also leads to three compression moduli, but distinct from those derived by Biot (Biot symmetry). However, there are two distinct solutions of this energy balance, corresponding to the Voigt and Reuss limits of the analogous theory of a linear two-phase elastic composite, whereas a unique undrained modulus not at either limit would be expected. It is proposed that an energy contribution is lost due to the idealised assumptions made for undrained loading, which therefore does not determine a further restriction, so that there are four independent compression moduli. The general and restricted combinations of the total pressure and fluid pressure (effective stress) governing the matrix compression are then presented, together with the alternative forms of the partial differential equations governing the deformation and flow. 相似文献
74.
An explicit stress formulation for stainless steel applicable in tension and compression 总被引:1,自引:0,他引:1
K. Abdella 《Journal of Constructional Steel Research》2007,63(3):326-331
In this paper an explicit stress formulation for stainless steel is presented. The formulation is applied to both tension and compression and it is an approximation to the closed form inversion of an existing two-stage stress-strain relation which is based on a modified Ramberg-Osgood equation. The validity of the explicit expression is tested over a wide range of material parameters. The tests demonstrate that the explicit formula is in excellent agreement with the fully iterated numerical solution of the full-range stress-strain relation. By incorporating an existing expression for deformation capacity, the proposed explicit formula is also used to obtain an explicit formulation for the computation of local buckling stress and compression resistance in terms of cross sectional slenderness. 相似文献
75.
分析和总结了沿纤维方向单轴拉伸时复合材料的破坏机理,提出了一种复合材料应力-应变行为的预测方法,并通过树脂基复合材料的拉伸破坏试验,对此方法进行了验证。 相似文献
76.
77.
78.
铝合金旋铆连接过程数值模拟分析 总被引:1,自引:0,他引:1
以铝合金基体件与钢板的旋铆连接工艺为对象,采用数值模拟手段和点追踪方法对铆钉成形过程进行了研究。主要分析了变形区的各个质点应力应变动态变化规律以及整个成形区的损伤分布情况,为有效地进行工艺研究、工艺设计提供了理论依据。 相似文献
79.
翁黎清 《锻压装备与制造技术》2007,42(6):67-68
为了解决具有异形内轮廓的冲压件翻边工序中易产生裂纹等缺陷,分析了异形内轮廓翻边成形时周向应变分散效应.首先分析了该类型零件的几何特点,然后在塑性力学中的平衡微分方程基础上,推导得到当翻边半径为某值时,变形区任意处的径向拉应力与切向拉应力的值.利用应力应变关系对翻边终了时孔的边缘切向拉应变作推导.结果表明,由于变形区材料之间的补充、牵制作用,在翻边高度一致的情况下,翻边系数计算应以最小内凹边半径段为准. 相似文献
80.
I. Emri J. Kramar A. Hribar A. Nikonov U. Florjančič 《Mechanics of Time-Dependent Materials》2006,10(3):245-262
This paper presents constitutive modeling of dynamically loaded elastomeric products such as power transmission belts. During
the normal operation of the belts certain segments of the belt structure are loaded with a tooth-like periodic (cyclic) loading.
When the time-dependent properties of the elastomeric material “match” the time-scale of the dynamic loading a strain accumulation
process occurs. The critical angular velocity is proportional to the ratio of the belt length to the common diameters of the
pulleys. The magnitude of the strain accumulated in each loading cycle decreases with an increase in belt length. For a given
belt geometry the critical angular velocity increases with the number of loading cycles. At the same time the magnitude of
the accumulated strain decreases non-linearly as the number of loading cycles increases. However if the belt operates at or
in the close vicinity of its critical angular velocity it will almost certainly fail!
The critical angular velocity depends on the material retardation time (location in the frequency spectrum), while the magnitude
of the accumulated strain is dictated by the strength of the corresponding discrete spectrum lines. Thus, the mechanical spectrum
of the elastomeric material from which the belt is constructed is the most important material function for predicting the
durability of drive belts and similarly dynamically loaded elastomeric products. 相似文献