共查询到20条相似文献,搜索用时 109 毫秒
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本通过实践与理论对岩爆进行了分析与研究,探讨了直接影响岩爆的几个主要因素,首次利用回归分析法对岩爆的有关数学模型进行了一些探讨,取得了一些结果,并且通过实践验证了所得结果的正确性,速对今后多方面进一步研究岩爆具有一定的指导意义。 相似文献
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偏斜应变能J*积分及应用 总被引:2,自引:0,他引:2
引进偏斜应变能的概念,对平面裂纹起裂扩展问题进行了讨论,给出了一个与路径无关的J^*积分,同时对其守恒性给予了严格的证明,通过Ⅰ型裂纹的应用,其结果与现行公开发表的献或手册结果一致。 相似文献
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本文对具有初速的有限长弹性杆与初始静止的有限长弹性地基梁的横向冲击问题进行了研究,用伽辽金原理求出了冲击力的近似公式并对结果进行了讨论,得出了有关结论. 相似文献
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G-函数与分块阵的特征值分布 总被引:1,自引:1,他引:0
利用由Nowosad和Hoffman提出的G-函数概念来刻划分块阵的特征值分布,对块对角占代性进行了G-函数推广,并研究它们的本质联系,获得了分块阵特征值若干包含域,以及M矩阵的充分条件.所得结果较已有结果,明显具有一般性. 相似文献
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资源公平分配的遗传算法研究 总被引:18,自引:5,他引:13
文章对决策优化的经典问题席位公平分配进行了研究,提出应用遗传算法对该模型进行求解。两例资源公平分配决策实例研究表明,遗传算法优化结果较其它方法都更合理。 相似文献
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一类单参数发展方程的时间周期解的分歧及其稳定性 总被引:1,自引:0,他引:1
本文应用渐近开和谱分析的方法,对发展方程的时间周期解的分歧及其稳定性进行了讨论,得到了存在性和稳定性判据的结果. 相似文献
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This numerical study investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under HCF conditions. The bending of cross-beam connections is simulated in ANSYS Workbench for three different combinations of beam profiles. The weldments are made of the high-strength steel grades C350LO and C450LO according to AS3678. The stress analysis of weldments is implemented with solid and shell elements using linear material and geometry consideration. The stress distributions are transferred to the embedded fatigue code nCode DesignLife. For both variants of FE-mesh, the nominal stress in the weld toes is extracted by splitting the total stress into membrane and bending components and filtering out non-linear component. Considering the effects of bending, size and mean stress, failure locations and fatigue life are predicted using the Volvo method and rules from ASME BPV Code. Three different pairs of experimental S-N curves (stiff and flexible) are used as material data input for fatigue analysis. The obtained numerical predictions are compared to the experimental results for shell FE-models. The predictions using the S-N curves for an equivalent steel demonstrate the best accuracy proving the fact that specific material data input is more effective than a generic data. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Jansons J. O. Glejbøl K. Rytter J. Aniskevich A. N. Arnautov A. K. Kulakov V. L. 《Mechanics of Composite Materials》2002,38(4):299-310
The influence of water absorption, under different temperatures and thermal aging in an oven, on the elastic and strength characteristics of carbon-fiber-reinforced epoxy composites is investigated by comparative tests in three-point bending. The tension-tension fatigue behavior of the composites is also studied. 相似文献
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Typical fracture surfaces are examined for polymethyl methacrylate specimens subjected to multicycle fatigue testing in circular cantilever bending at T=20, 40, and 60°C. It is established that the fatigue life of smooth specimens is very closely correlated with the size of the diffuse fracture zone. The kinetics of damage accumulation with increase in the number of cycles are investigated by rapidly fracturing prefatigued specimens. The decisive role of diffuse fracture in the fatigue-fracture process is demonstrated. A method of estimating the mean main crack propagation velocity in circular bending is described.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 984–990, November–December, 1973. 相似文献
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The prediction of the high-cycle fatigue strength of polymeric and composite materials in asymmetric loading is considered.
The problem is solved on the basis of a nonlinear model of ultimate state allowing us to describe all typical forms of the
diagrams of ultimate stresses. The material constants of the model are determined from the results of fatigue tests in symmetric
reversed cycling, in a single fatigue test with the minimum stress equal to zero, and in a short-term strength test. The fatigue
strength characteristics of some polymers, glass-fiber laminates, glass-fiber-reinforced plastics, organic-fiber-reinforced
plastics, and wood laminates in asymmetric tension-compression, bending, and torsion have been calculated and approved experimentally.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 1, pp. 87–102, January–February, 2008. 相似文献
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考虑到膜盘的内外缘的刚性远较膜面为大,并且非对称弯曲是在高速旋转运动下,而引进了中面等半径圆假设,即膜盘中面上的每个同心圆变形前后半径不变,但同心圆所在的平面各自发生了角度不同的偏转.在此基础上,通过能量变分原理,导出了相应变形的Euler方程.该方程具有首次积分,忽略一些次要项后,可得到变形的解析解.通过对双曲型面的膜盘计算表明,非对称弯曲下的八面体剪应力在径向及厚向上都变化很小,可近似认为不变,但周向上呈明显脉动变化,因此非对称弯曲对膜盘的疲劳寿命有重要影响. 相似文献
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This examines the fracture surfaces in polymethyl methacrylate (PMMA) obtained during fatigue testing of small specimens with round console bending in the presence of a heating hysteresis. It is shown that the accumulation of damage at all stages of the process of fatigue breakdown, as in the case of stabilized temperatures, has a scatter failure characteristic. 相似文献
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The fracture and stress redistribution processes in a specimen stressed in cyclic bending with rotation are considered. The calculations are based on the assumption of linear damage accumulation and a linear dependence of the modulus of elasticity on the damage; the fatigue strength curve for cyclic tension-compression is employed. The calculated damage accumulation and crack penetration times are compared. Specific calculations are made for the case of PMMA fatigue under isothermal conditions.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 875–880, September–October, 1971. 相似文献
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Conclusions The behavior of the PEO films under long-term loadings show certain special features reflected mainly in the unusual form of the fatigue curve and the presence of three types of creep curves. The most significant factors affecting the fatigue characteristics of the PEO films are the molecular mass and the degree of crystallinity — when these factors increase the fatigue resistance also usually increases. To evaluate suitability of PEO films for service it is promising to use the cyclic bending test. This loading mode characteristic of practice makes it possible to carry out tests at low strain levels and cumulate considerable damage. Examination by the x ray diffraction method showed that in cyclically bent PEO films not only the amorphous but also crystalline structures are damaged.Translated from Mekhanika Kompozitnykh Materialov, Vol. 3, No. 3, pp. 404–412, May–June, 1994. 相似文献
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