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51.
Abstract A special finite element method (FEM) programme has been developed, reflected all significant phenomena connected with assembly and exploration of the Belt chamber. A nonhomogeneous temperature field is taken into account. Isotropic, kinematic and mixed hardening rules can be considered. 相似文献
52.
Robert S. Hoy 《Journal of Polymer Science.Polymer Physics》2011,49(14):979-984
In this Perspective, I describe recent work on systems in which the traditional distinctions between (i) unentangled versus well‐entangled systems and (ii) melts versus glasses seem least useful, and argue for the broader use in glassy polymer mechanics of two more dichotomies: systems which possess (iii) unary versus binary and (iv) cooperative versus noncooperative relaxation dynamics. I discuss the applicability of (iii–iv) to understanding the functional form of strain hardening. Results from molecular dynamics simulations show that the “dramatic” hardening observed in densely entangled systems is associated with a crossover from unary, noncooperative to binary, cooperative relaxation as strain increases; chains stretch between entanglement points, altering the character of local plasticity. Promising approaches for future research along these lines are discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
53.
A new approach to modeling crystallographic texture evolution in Equal Channel Angular Extrusion (ECAE) is presented in this paper. The proposed approach utilizes an elastic–viscoplastic single crystal constitutive model implemented in a finite element framework. A representative volume element of the polycrystal is subjected to boundary conditions that simulate the approximate deformation history experienced by different regions of the sample (at different through-thickness depths) in both Route A and Route C processing. The proposed approach aims to capture the influence of the complex interactions that ensue among the constituent individual crystals of a polycrystal in controlling the texture evolution in the sample, while capturing the boundary conditions inherent to ECAE deformation. The predictions from the proposed approach are compared against previously reported experimental measurements in ECAE of copper. It is observed that the proposed approach provides significantly better agreement with the measurements when compared against previously reported model predictions. 相似文献
54.
孔洞受压的统一极限分析 总被引:1,自引:0,他引:1
采用俞茂宏统一强度理论分别就平面应变和平面应力总是对受压孔洞进行了极限分析,得到了各自的统一解形式。以往的基于Tresca、Mises、双剪屈服准则以及Mohr-Coulomb强度理论的极限解均为本文统一解的特例。此解可以适应于广泛的不同性质的各灯材料,合理也得出不同材料的相应解。 相似文献
55.
袁丽莉 《宁波大学学报(理工版)》2008,21(3):392-394
分析了跨高比、加载方式对预应力混凝土梁抗弯强度和结构性能的影响.利用平面梁弯曲理论导出单元切线刚度矩阵,提出了新的分析模型可用于预测预应力混凝土梁从开始加载直至失效的非线性全过程响应,并利用建立的分析模型详细评估了跨高比及加载方式等参数对预应力混凝土梁的弯曲强度和受力性能的影响. 相似文献
56.
提出分析中心裂纹板剪切断裂的断裂过程区D-B模型的叠加原理,考虑了压剪断裂的摩擦阻力和体现有限权宽影响的载荷修正,以非常简便的方法推导出计算断裂过程区长度和位移的公式。 相似文献
57.
F. Kun S. Zapperi H.J. Herrmann 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(2):269-279
We introduce a continuous damage fiber bundle model and compare its behavior with that of dry fiber bundles. Several interesting
constitutive behaviors, such as plasticity, are found in this model depending on the value of the damage parameter and on
the form of the disorder distribution. We compare the constitutive behavior of global load transfer models, obtained analytically,
with local load transfer models numerical simulations. The evolution of the damage is studied analyzing the cluster statistics
for dry and continous damage fiber bundles. Finally, it is shown that quenched random thresholds enhance damage localization.
Received 27 March 2000 相似文献
58.
The plastic behavior of micro- and nano-scale crystalline pillars is investigated under nominally uniform compression. The transition from forest hardening to exhaustion hardening dominated behavior is shown to emerge from discrete dislocation dynamics simulations upon reduction in the initial source density. The analyses provide new insight into the scaling of flow stress with specimen size and also highlight the connection between individual dislocation mechanisms, collective phenomena and overall behavior. 相似文献
59.
Tung‐Kung Wu Cheng‐Hsiang Chang Yuan‐Ting Liu Tsai‐Ting Wang 《Chemical record (New York, N.Y.)》2008,8(5):302-325
The oxidosqualene cyclases (EC 5.4.99‐) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)‐2,3‐oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure–function relationships of the Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase‐catalyzed cyclization/rearrangement reaction. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 302–325; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20157 相似文献
60.