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921.
Flow and fracture of rocks under general triaxial compression 总被引:1,自引:0,他引:1
Recent laboratory studies of the flow and fracture of rocks under general triaxial compression are reviewed. New developments in laboratory techniques have made it possible to measure three principal stresses and strains under general triaxial stress states, in which all three principal stresses are different.Strength and ductility of isotropic rocks are markedly affected not only by the least compression 3, but also by the intermediate compression 2, although these two effects are rather additional in strength, but opposite in ductility. The experimental results show that dilatancy is highly anisotropic under the general triaxial stress states.Deformational properties of anisotropic rocks have been also measured under the general triaxial compression. In this case, the effect of the intermediate compression markedly depends on the orientations of the weak planes. 相似文献
922.
Nonlinear bending of circular sandwich plates 总被引:2,自引:0,他引:2
刘人怀 《应用数学和力学(英文版)》1981,2(2):189-208
In this paper, fundamental equations and boundary conditions of nonlinear axisymmetrical bending theory for the circular sandwich plates with a soft core are derived by means of the method of calculus of variations. Especially in the case of very thin faces, the preceding fundamental epuations and boundary conditions simplity considerably. For example, a circular sandwich plate with edge clamped but free to siip under the action of uniform lateral load is considered. A more accurate solution of this problem has been obtained by means of the modified iteration method.Notation
r, ,z
system of cylindrical coordinates
-
a
radius of plate boundary
-
t
thickness of the face
-
h
thickness of the core
-
h
0
distance from middle of thickness of lower face to middle of thickness of upper face
-
E
Young's modulus of the face
-
Poisson's ratio of the face
-
G
2
shear modulus of the core
-
D
f
flexural rigidity of the face
-
D
flexural rigidity of the plate
-
C
shear rigidity of the plate
-
q
uniform lateral load
-
u
i
,v
i
,w
i(i=1, 2, 3)
radial, tangential and normal displacement of upper face, core and lower face, respectively
-
u
radial displacement of the middle plane of the plate
-
w
deflection of the middle plane of the plate
-
rotation of connecting line of corresponding points in middle planes of two faces
-
1i
,
i
,
zi
,
ri
,
zi
,
rzi (i=1,2,3)
strains at a point of upper face, core and lower face
-
ri
,
i
,
zi
,
ri
,
zi
,
rzi(i=1,2,3)
stresses at a point of upper face, core and lower face
-
r
,
0
radial and tangential stress of the middle plane of the plate, respectively
-
U
i(i
=1, 2, 3)
strain energy of upper face, core and lower face, respectively
-
V
work done by the external force
-
U
total potential energy of the plate
-
M
r
radial moment of the plate
-
Q
r
shearing force of the plate
-
m
radial moment of the face
-
stress function
-
dimensionless radial coordinate
-
k
dimensionless characteristic parameter
-
W
dimensionless deflection
-
W
0
dimensionless center deflection
-
S
r
,S
0
dimensionless radial and tangential stress, respectively
-
S
r
(0),S
0 (0)
dimensionless radial and tangential stress at center, respectively
-
S
0(1)
dimensionless tangential stress at edge
-
P
dimensionless uniform lateral load
-
A
2,A
3,B
2,B
3,a
1,.....,a
2,
1,
2,l
1,1,...l
1 1,3,m
1,...,m
33,n
0,2,...n
22,6,R
1,,...R
33
auxiliary quantity
-
L
differential operator 相似文献
923.
江福汝 《应用数学和力学(英文版)》1982,3(5):683-695
In this paper we consider the nonlinear and unsymmetrical bendings of annular and circular thin plates under various supports. The uniformly valid asymptotic solutions have been derived by means of the perturbation method presented in [7]. 相似文献
924.
Single crystals of the quaternary crystalline solid solution system RbxK1‐xBryCl1‐y have been grown by melt technique for three different compositions y = 0.25, 0.50 and 0.75, keeping x = 0.5 and X‐ray diffraction studies have been carried out for each case independently, using spherically ground single crystals. The results indicate an enhancement of Debye‐Waller B(total) factors for the compositions y = 0.25 and 0.75 whereas for the intermediate composition, y = 0.5, the factor B(total) is close to the end member value. This experimental investigation show that for this composition, the crystalline solid solution behaves like an end member crystal. 相似文献
925.
926.
The concept of sweeping has been used in electrokinetic chromatography to explain the concentrating mechanism in micellar electrokinetic chromatography when the sample matrix is a high resistivity non-micellar aqueous solution. Theoretical and experimental studies were undertaken. It was found that the total focusing effect is brought about by the cumulative effect of sweeping and sample stacking. For better analytical results, compounds showing low to moderate retention factors (k) and compounds showing high values of k must be dissolved in low and high conductivity matrices, respectively. 相似文献
927.
928.
为探讨施用增效肥料后对土壤富里酸(F A)荧光特性及腐殖化程度的影响,在黑龙江省黑河市嫩江县和爱辉区两个试验区采取相同施肥处理,设置5个处理组:平衡施肥(NE)、平衡施肥减量25%(CK)、平衡施肥减量25%+纳米碳增效剂(T 1)、平衡施肥减量25%+沸石增效剂(T 2)、平衡施肥减量25%+生物炭增效剂(T3),分... 相似文献
929.
探讨2型糖尿病合并大血管病变的相关危险致病因素, 以期指导制定自我管理方案. 采用回顾性病例-对照研究方法, 选2型糖尿病患者85例, 根据是否合并大血管病变, 分为单纯2型糖尿病组(T2DM组, n=41)及合并大血管病变组(T2DM+MV组, n=44), 选同期的40例非糖尿病患者作为对照, 比较各组患者的一般资料及入院时的血压、血清镁、空腹血糖、糖化血红蛋白和血脂水平等参数. 结果表明 糖尿病病程(比值比(OR)=1.268, 95%置信区间(CI) 1.076~1.496)、空腹血糖(OR=2.147, 95% CI 1.167~3.949)及糖化血红蛋白水平(OR=4.936, 95% CI 1.575~15.470)是2型糖尿病患者并发大血管病变的独立危险因素, 而血清镁水平则是独立保护性因素(OR=0.001, 95% CI 0.000~0.014). 同时表明, 在2型糖尿病早期自我管理中, 积极控制血糖及维持血清镁在较高水平是预防大血管病变的有效途径. 相似文献
930.
牟自强 《宁波大学学报(理工版)》2001,14(3):79-83
介绍一种特殊对称的跨中带直线段的圆弧梁,在4种常用荷载作用下的内力计算方法,导出了一套内力计算公式,可供设计时直接查用. 相似文献