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31.
Wei Tong 《Experimental Mechanics》2004,44(5):502-511
A technique using a single CCD camera, a precision rotation/translation stage, a telecentric zoom lens, and digital image
correlation software is described for measuring surface profiles and surface plastic strain distributions of a bent thin sheet.
The measurement principles, based on both parallel and pinhole perspective projections, are outlined and the relevant mathematical
equations for computing the profiles and displacement fields on a curved surface are presented. The typical optical setup
as well as the experimental measurement and digital image correlation analysis procedure are described. The maximum errors
in the in-plane and out-of-plane coordinates or displacements are about ±5 and ±25 μm, respectively, and the maximum errors
in surface strain mapping are about 0.1% or less based on a series of evaluation tests on flat and curved sample surfaces
over a physical field of view of 15.2 × 11.4 mm2. As an application example, the shape and surface plastic strain distribution example, the shape and surface plastic strain
distributions around a bent apex of a flat 2 mm thick automotive aluminum AA5182-O sheet, which underwent a 90° bend with
three bend ratios of 2t, 1t, and 0.6t, are determined using the proposed technique. 相似文献
32.
考虑晶界效应的多晶体有限变形分析 总被引:1,自引:0,他引:1
将晶界及其影响区综合考虑,建立了考虑晶界效应的力学模型,结合晶体塑性理论,利用有限变形有限元对多晶体进行数值模拟,数值结果显示了细观层次下晶粒变形场的特点,理论计算同实验定性一致。 相似文献
33.
圆形截面是工程中常使用的截面形式之一,但圆形截面的配筋计算较为困难,存在双重非线性(材料和截面宽度变化的非线性),《混凝土结构设计规范》给出了计算均匀配筋的超越方程组,且须迭代求解,无法手算.另外,一些圆形截面构件(如桥墩、桩基的预制桩和灌注桩等)的截面尺寸大,构件长,钢筋用量大,若采用均匀布置的配筋方式,中性轴附近的钢筋应力小,强度利用率低,经济性差.若采用非均匀配筋,在远离中性轴的外围区域布置受力钢筋,可大幅节省钢筋用量,且能充分利用钢筋及混凝土的强度.为此本文通过应变计算应力,再计算出内力的方法推导计算圆形截面配筋的公式,并将计算结果绘制成了能计算配筋的无量纲诺模图,由此可快速手算配筋,该图通用性强,可用于任意直径大小及C50以下的混凝土强度等级,是一能快速计算配筋的实用工具. 相似文献
34.
爆炸荷载下矩形板的塑性动力响应 总被引:8,自引:1,他引:8
本文采用Jones-Sawczuk控制方程,导出了脉冲荷载下矩形板最大残余挠度的简单理论计算公式,并应用该公式和动态屈服条件,计算了固支方板在爆炸荷载下的最大残余挠度值,与试验结果比较,取得了令人满意的结果。 相似文献
35.
Nonlinear static and dynamic analysis for laminated,annular, spherical caps of moderate thickness 总被引:1,自引:0,他引:1
Based on Timoshenko-Mindlin kinematic hypothesis, the shallow shell theory is extended to include the transverse shear deformation for the nonlinear axisymmetric dynamic analysis of the symmetric cross-ply shallow spherical shell. Using the orthogonal point collocation method and the Newmark scheme, an iterative solution is formulated. The numerical results for the nonlinear static and dynamic responses and dynamic buckling of these shallow spherical shells with circular holes under uniformly distributed static or dynamic normal impact loads are presented and compared with available data. 相似文献
36.
H.B.H. Gubran 《Mechanics Research Communications》2005,32(4):368-374
In this paper the dynamic performance and cross-section deformation of shafts made of metals (steel and aluminum), composites (CFRP and GFRP) and hybrids of metals and composites have been studied. A layered finite degenerated shell element with transverse shear deformation and dynamic behavior is employed. Results obtained show that improvements in dynamic performance and reduction of cross-section deformation of hybrid shafts over metallic and composite shafts are possible. 相似文献
37.
38.
拉压性能不同材料全量型本构关系及厚壁筒的应力分析 总被引:1,自引:0,他引:1
将经典全量理论作了推广,考虑了应力状态及塑性体积变形对拉压性能不同材料的塑性行为的影响。应用该本构模型分别计算了厚壁筒在内压和外压作用下的应力分布。给出了径向应力、环向应力和轴向应力沿壁厚的分布图。将本文的计算解与拉压性能相同(不考虑体积变形、强化曲线唯一)的幂函数强化材料的厚壁筒的理论解进行了比较。结果表明,材料的拉压性能不同对厚壁筒的环向应力和轴向应力影响较大。因此,对于拉压性能不同材料,考虑到其对应力状态及塑性体积变形敏感时,是不能将其简化成拉压性能相同、体积不可压缩、强化曲线唯一的理想材料。 相似文献
39.
For axially symmetric deformations of the perfectly elastic neo-Hookean and Mooney materials, formal series solutions are
determined in terms of expansions in appropriate powers of 1/R, where R is the cylindrical polar coordinate for the material coordinates. Remarkably, for both the neo-Hookean and Mooney materials,
the first three terms of such expansions can be completely determined analytically in terms of elementary integrals. From
the incompressibility condition and the equilibrium equations, the six unknown deformation functions, appearing in the first
three terms can be reduced to five formal integrations involving in total seven arbitrary constants A, B, C, D, E, H and k
2, and a further five integration constants, making a total of 12 integration constants for the deformation field. The solutions
obtained for the neo-Hookean material are applied to the problem of the axial compression of a cylindrical rubber tube which
has bonded metal end-plates. The solution so determined is approximate in two senses; namely as an approximate solution of
the governing equations and for which the stress free and displacement boundary conditions are satisfied in an average manner
only. The resulting load-deflection relation is shown graphically. The solution so determined, although approximate, attempts
to solve a problem not previously tackled in the literature.
相似文献
40.
A. M. Zenkour 《Archive of Applied Mechanics (Ingenieur Archiv)》2004,74(3-4):262-276
Summary The static and dynamic responses of anisotropic spherical shells under a uniformly distributed transverse load are investigated.
Analytical solutions using the mixed variational formulation are presented for spherical shells subjected to various boundary
conditions. Numerical results of a refined mixed first-order shear deformation theory for natural frequencies, critical buckling,
center deflections and stresses are compared with those obtained using the classical shell theory. A variety of simply-supported
and clamped boundary conditions are considered and comparisons with the existing literature are made. The sample numerical
results presented herein for global structural behaviour of monoclinic spherical shells should serve as references for future
comparisons. 相似文献