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铝合金具有轻质高强、延性好、低温脆断敏感性小、耐腐蚀等优点,可用于侵蚀环境及寒冷环境下结构体外预应力加固工程.本文对铝合金筋的材料性能进行试验研究,建立了铝合金筋本构关系模型,应用有限元程序ANSYS对既有体外预应力加固混凝土梁的受力过程进行模拟分析,通过计算结果和试验结果的对比分析验证了有限元分析模型的合理性.根据等截面原则和等强度原则,应用铝合金筋分别替换既有混凝土梁的体外预应力筋,对其进行有限元分析.结果表明,与传统体外预应力加固混凝土梁相比,采用等截面原则加固后的铝合金筋体外预应力混凝土梁,可以在适当提高延性的基础上,部分提高混凝土梁的承载能力;采用等强度原则加固后的铝合金筋体外预应力混凝土梁,可同时显著提高混凝土梁的承载能力和延性. 相似文献
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在工程结构的优化设计中,应用遗传算法的基本原理,研究了离散设计变量全局寻优等传统优化方法难于解决的特殊问题。以平面桁架梁作为解析例,选取桁架的节点坐标和杆件的截面特征为设计参数,模拟遗传操作过程中的生物进化机制,对桁架的构成和形状的优化问题进行了解析。得到桁架在不同情况下的形状优化解,并使桁架质量趋于最小。研究结果验证了遗传算法在桁架的形状最优化和最小质量设计中应用的可行性。 相似文献
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本文研究了简支梁在各种集中力作用下的弯曲强度,指出了目前材料力学教材中“把较大的集中力分散成较小的力,作为提高梁弯曲强度措施之一的不全面处。同时,认为设法避免梁中间直接作用集中力可作为提高梁弯曲强度的措施。 相似文献
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有限元方法是材料力学性能分析的主要工具.对于颗粒增强复合材料,其增强相或夹杂多为不规则的多边形,共采用经典有限元分析,需划分稠密的计算网格,降低分析效率.本文以多边形为有限元计算单元,采用Wachspress作为试函数,建立分析非均质材料力学性能的多边形有限元方法,给出形函数计算的简化公式.多边形单元的位移插值采用Wachspress插值,能自动满足不同形状单元间的协调性.计算网格按照材料分布的真实结构划分为若干多边形单元.数值算例验证了多边形有限元在模拟非均质材料力学性能方面的有效性和计算精度. 相似文献
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为研究钢纤维混凝土损伤破坏过程和裂纹发展演化机理,基于分形理论和扩展有限元法,建立钢纤维混凝土立方体抗拉试验细观有限元模型和切口梁三点弯曲试验有限元模型,以相关试验测试结果为基础,比较验证了所建有限元分析模型的可靠性。以裂纹分形维数表征钢纤维混凝土损伤演化过程,考察不同钢纤维体积掺量和长度、粗骨料形状等重要因素对钢纤维混凝土损伤演化过程的影响。结果表明,基于裂纹分形维数的损伤值可以较好地反映钢纤维混凝土的损伤演化过程及特征,钢纤维体积掺量、长度的增加和骨料形状的不规则化会延缓钢纤维混凝土立方体试件的损伤演化过程,钢纤维体积掺量、初始裂纹距跨中距离的增加和初始裂纹缝高比的减小可在较小程度上延缓钢纤维混凝土切口梁的损伤演化过程。 相似文献
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René Quispe Rodríguez Renato Picelli Paulo Sollero Renato Pavanello 《Journal of Adhesion Science and Technology》2014,28(14-15):1451-1466
This work presents an application of the evolutionary structural optimization (ESO) method to optimize two of the most common bonded joints – the single lap joint and the double lap joint. The ESO method was used to shape the adherends contour to reduce peak stresses at the overlap ends. The shape optimization was performed under a von Mises rejection criterion. The von Mises stress was evaluated using the finite element model for both types of joints. It is proposed here to utilize a honeycomb-like mesh using hexagonal elements to minimize stress concentration problem. Additionally, the use of a honeycomb mesh in the ESO method led to a smoother adherend contour. Numerical results show how the stress distributions for both shear and peel stresses are improved after the application of this optimization method. 相似文献
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将有限元应力分析方法与设计方法相结合 ,提出了基于受压容器口补强的极限分析理论和优化设计思想 ,采用有限元前处理程序 ,自动生成常见球罐和柱罐的优化力学模型 ,并在屏幕上或用汇图仪绘制出罐体的三维图形。建立起受压容器开口补强优化设计的教学模型。根据此问题的特殊性 ,采用改进后的 0 .6 1 8法进行优化计算 ,优化过程中将模型划分成可变域和不可变域两部分 ,利用计算机的顺序文件存贮不变域单元刚度阵 ,提高了有限元重分析的计算效率 相似文献
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A finite element optimization method is presented that determines the optimal thickness profile of a preform for a blow-molded part having the required wall thickness distribution. The optimization method is based on a method of feasible directions and the design variables are thicknesses of finite elements. The step size is determined by using a Brent 1-dimensional minimization method. Two methods for determining feasible directions are compared. A finite element model is formulated based on the thin membrane approximation, which relates the preform wall thickness distribution to the wall thickness distribution in the blow-molded part. Triangular or conical frustra elements are used to describe deformed shapes of the preform for 2-dimensional axisymmetric deformations. An incompressible nonlinear elastic constitutive model describes the material response. The accuracy of the finite element model used is evaluated by comparing the model predictions to published experimental data and computer simulations. 相似文献
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A. Karagiannis H. Mavridis A. N. Hrymak J. Vlachopoulos 《Polymer Engineering and Science》1988,28(15):982-988
The unidirectional flow of two immiscible fluids with different viscosities in a long die of arbitrary shape is considered. Mathematically, the problem has a continuum of solutions corresponding to arbitrarily prescribed interface shapes, but experimental evidence indicates the existence of a unique interface shape with the less viscous fluid encapsulating the more viscous fluid. With the introduction of the minimum viscous dissipation principle, which postulates that the amount of viscous dissipation is minimized for a given flow rate, the problem becomes a nonlinearly constrained optimization problem. A generalized reduced gradient/finite element method combination is used to predict the interface shape when two inelastic fluids are considered. The effect of the viscosity ratio and flow-rate ratio on the interface shape is examined for different die geometries. Inner layer breakup phenomena are predicted and explained for complex die geometries. 相似文献
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随着功能梯度梁的跨高比从小(厚梁)变到大(薄梁),梁的变形受到剪切变形的影响就会从大变到小。为了准确分析功能梯度梁的变形,跨高比小的厚梁采用Timoshenko梁模型,而跨高比大的薄梁采用Euler-Bernoulli梁模型。采用这两种梁模型进行功能梯度梁自由振动的有限元计算,分析单元刚度矩阵、质量矩阵和模态阵型等存在的差异。通过数值算例,研究了这两种梁模型的差异对模态应变能法的损伤识别指标的影响。对于厚梁,Timoshenko梁模型的损伤指标优于Euler-Bernoulli梁模型;对于很薄的梁(例如,l/h=25时的薄梁),Euler-Bernoulli梁模型的损伤指标优于Timoshenko梁模型。 相似文献
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本文基于对复合材料孔板主承力接触区的有限元强度分析结果,利用APDL参数化有限元分析技术,以孔板第一主应力S1和X方向上的变形UX的最大值作为目标函数,对孔形参数进行优化。设计出基于应力和变形最小的开口形状,并得出了孔形参数与应力、变形之间的相互关系。 相似文献