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991.
Path Independent Integral for an Elliptical Hole in a Plate under Tension for Plane Stress Deformation Theory 总被引:1,自引:0,他引:1
David J. Unger 《Journal of Elasticity》2008,92(3):217-226
An exact expression is derived for a path independent integral surrounding an elliptical hole in an infinite plate with tensile
tractions at infinity for plane stress loading conditions. The plate is composed of a non-work-hardening material satisfying
the Tresca yield condition under proportional loading and small strain assumptions. This problem may serve as a simple classroom
example for the derivation of a relationship between crack opening displacement and path independent integral for a nonlinear
elastic material satisfying the Tresca yield condition.
相似文献
992.
Crack line analysis is an effective way to solve elastic-plastic crack problems.Application of the method does not need the traditional small-scale yielding conditions and can obtain sufficiently accurate solutions near the crack line. To address mode-Ⅲ crack problems under the perfect elastic-plastic condition,matching procedures of the crack line analysis method are summarized and refined to give general forms and formulation steps of plastic field,elastic-plastic boundary,and elastic-plastic matching equations near the crack line. The research unifies mode-Ⅲ crack problems under different conditions into a problem of determining four integral constants with four matching equations.An example is given to verify correctness,conciseness,and generality of the procedure. 相似文献
993.
用于聚合物驱油的抽油杆动力学分析 总被引:1,自引:0,他引:1
聚驱井与水驱井相比杆管偏磨更加严重,聚驱井采出液的法向力是加剧偏磨
的重要因素之一. 根据非牛顿流体力学理论,采用上随体Maxwell模型,建立了法向力计算
模型,确定了井筒内法向力的分布规律,并将此法向力施加在抽油杆的瞬态动力学
模型中; 考虑实际边界条件,采用有限元法对聚驱抽油杆进行了分析计算. 并对FU081801
井模拟计算进行验证,模拟结果与作业检测结果吻合较好,证明了该方法的可行性. 通过此
方法可预测出聚驱井杆管的偏磨位置以及聚合物浓度对抽油杆偏磨的影响程度. 相似文献
994.
Vincent Monchiet Oana Cazacu Eric Charkaluk Djimedo Kondo 《International Journal of Plasticity》2008,24(7):1158-1189
The combined effects of void shape and matrix anisotropy on the macroscopic response of ductile porous solids is investigated. The Gologanu–Leblond–Devaux’s (GLD) analysis of an rigid-ideal plastic (von Mises) spheroidal volume containing a confocal spheroidal cavity loaded axisymmetrically is extended to the case when the matrix is anisotropic (obeying Hill’s [Hill, R., 1948. A theory of yielding and plastic flow of anisotropic solids. Proc. Roy. Soc. London A 193, 281–297] anisotropic yield criterion) and the representative volume element is subjected to arbitrary deformation. To derive the overall anisotropic yield criterion, a limit analysis approach is used. Conditions of homogeneous boundary strain rate are imposed on every ellipsoidal confocal with the cavity. A two-field trial velocity satisfying these boundary conditions are considered. It is shown that for cylindrical and spherical void geometries, the proposed criterion reduces to existing anisotropic Gurson-like yield criteria. Furthermore, it is shown that for the case when the matrix is considered isotropic, the new results provide a rigorous generalization to the GLD model. Finally, the accuracy of the proposed approximate yield criterion for plastic anisotropic media containing non-spherical voids is assessed through comparison with numerical results. 相似文献
995.
996.
997.
微波溶样流动注射分光光度法在线测定金矿石中的金 总被引:5,自引:0,他引:5
采用微波溶样 流动注射在线泡塑富集分离 分光光度联用技术建立了在线快速测定金矿石中金的方法。比较了微波溶样法与传统电热板溶样法,二者结果基本一致。前者溶样时间近似为后者的1 9。确定了两条工作曲线:校正曲线范围为0 1~1.0μg mL,检出限2.2×10-2μg mL;校正曲线范围为1.0~9 0μg mL,检出限1.6×10-1μg mL。FI SP系统分散系数为3.78。对管理样GBW(E) 070014平行11次测定,其RSD为1.3%,对所得结果进行t检验,置信度95%时,无系统误差存在。 相似文献
998.
R. Schlegel M. Thunga G. Heinrich Jimmy W. Mays H. Iatrou 《European Polymer Journal》2009,45(10):2902-9383
The stress-strain behaviour of multigraft copolymers consisting of a polyisoprene (PI) backbone and grafted polystyrene (PS) arms have been characterized by applying models of rubber elasticity such as Mooney-Rivlin, slip-tube and the extended non-affine tube model. Additionally, the range of low deformation has been investigated by relaxation tests for determining the stress relaxation. Multigraft copolymers show high strain at break and low residual strain caused by the large number of physical cross links resulting from several grafted PS side chains. From the model fits the material parameters and of the slip-tube model, representing the influence of chemical cross links and entanglements effects, respectively, and the ne/Te-value (ne - number of statistical segments between two successive entanglements, Te - Langley trapping factor) of the extended non-affine tube model, are used to describe the tensile behaviour of these thermoplastic elastomers. The PS content was considered as filler phase taking into account the effect of hydrodynamic amplification. The influence of functionality and the number of branch points per molecule on the strain at break and the tensile strength is explained by the model parameters describing the stress-strain curve at low to medium (?400%, slip-tube, Mooney-Rivlin) and low to high (?900%, extended non-affine tube) elongations. It was observed that for the material with a spherical morphology is increasing with the number of branch points β (each branch point consists of a PI backbone segment, depending on the functionality one, two or four grafted PS arms). For cylindrical and lamellar morphologies the was decreasing with increasing β, which could be reconfirmed by applying the extended non-affine tube model where the ne/Te-parameter is increasing with β. 相似文献
999.
Hydrogels are finding increasingly broad use, especially in biomedical applications. Their complex structure – a low-density network of microfibrils – defines their non-trivial mechanical behaviour. The focus of this work is on test-based quantification of mechanical behaviour of a bacterial cellulose (BC) hydrogel exposed to cyclic loading. Specimens for the tests were produced using Gluconacetobacter xylinus ATCC 53582 and tested in aqua under uniaxial cyclic loading conditions in a displacement-controlled regime. Substantial microstructural changes were observed in the process of deformation. A combination of qualitative microstructural observations with quantitative force-displacement relations allowed identification of main deformation mechanisms, confirming inelastic behaviour of the BC hydrogel under a loading-unloading-reloading regime. Elastic deformation was accompanied by non-elastic (viscoplastic) deformation in both tension and compression. This study also aims to establish a background for micromechanical modelling of overall properties of BC hydrogels. 相似文献
1000.
In this Letter, the plastic relaxation introduced by typical 60° mixed dislocation in zinc‐blende axial nanowire (NW) heterostructures is evaluated by numerical Peach–Koehler approach which reflects the interaction between coherent strain field and misfit dislocation. Cylindrical NW epilayers grown on NW and bulk substrate are separately modeled. We reveal that straight 60° dislocation with Burgers vector (a /2) 〈101〉 would always generate at NW center orienting [111], while aspect ratio dependent off‐center equilibrium position should be expected for NW epilayer along [001]. Moreover, the critical diameters, below which coherency is maintained, are predicted based on energy balance criterion for axial NW heterostructures along predominating growth direction [111]. The results are compared with existing theory and experimental observations. Our work provides a necessary quantitative complement to the understanding of plastic relaxation and coherency limit in axial NW heteroepitaxy. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献