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1.
为合理描述超固结土复杂的弹塑性力学行为,对现有Hashiguchi次加载面模型中的超固结状态参量R进行修正,在硬化方程中,考虑塑性体应变与塑性剪应变的综合作用,提出了修正超固结状态参量的次加载面模型。同时,着重介绍了该模型的隐式积分算法及数值实现过程,编制了对应的接口子程序,实现了该模型在有限元软件ABAQUS中的应用。通过不同工况和加载方式下的数值模拟验证了程序的合理性,最后应用模型研究了Fujinomori 黏土的三轴压缩力学特性并与UH模型的模拟结果、室内试验研究进行对比。结果表明,子程序具有较高的计算精度和可靠性,模型能够准确地模拟黏土的超固结特性。 相似文献
2.
采用蚁群算法对食品机械四杆机构进行最优化设计,分析建立杆尺寸间的几何联系,并结合具体实例确定四杆机构各个参数。介绍了蚁群算法的模型和算法实现过程。说明了蚁群算法应用于机械优化计算切实可行,它使设计快速、计算精确、设计结果可靠,为复杂的机械优化设计问题提供了新的思路和方法。 相似文献
3.
基于量子多种群遗传算法的蛋白质二级结构预测 总被引：1，自引：1，他引：0
为进一步提高蛋白质二级结构的预测精度,将量子计算和多种群算法融入到传统的遗传神经网络算法中。同时考虑到氨基酸残基的众多理化性质是形成蛋白质二级结构的主要驱动力,构象偏好也是影响蛋白质二级结构形成的重要因素,提出了一种新的基于理化性质和构象信息编码的量子多种群遗传算法。该方法蕴含了丰富的生物信息,可以有效减少网络系统的不确定性。用PDBselect25中的24条蛋白质进行测试,结果表明该算法可以有效的预测蛋白质的二级结构,平均预测精度达到72.10%,分别比SNN、DSC、PREDSATOR方法提高了7.80%、3.70%和3.41%。该方法采用混合编码的形式进行编码,在每个种群内部引入量子计算,形成了以多种群遗传算法来带动量子计算,量子计算反作用于多种群算法的双重优化的方法,可有效提高蛋白质二级结构预测的精确度。 相似文献
4.
基于等效原则、相似理论,考虑三维地震动作用下振动台试验中原型结构隔震层的简化,并对模型结构隔震层进行系统研究。针对不同高宽比隔震结构,提出完全等效简化方法和部分等效简化方法,包括隔震垫等效、模型支座参数及坐标确定、相似关系确定等。利用不同高宽比隔震结构振动台试验,结合有限元数值模拟,进行方法验证。理论推导与数值模拟证明简化方法具有良好的准确性,且在误差允许范围内,简化后的隔震层所获得的加速度、速度、位移等动力特性与简化前相同,可以用于振动台试验模型设计。 相似文献
5.
对砂土地基上圆形浅基础在竖向荷载V、水平荷载H及力矩M复合加载条件下的承载力进行了系统的三维有限元分析。在分析中,砂土假定为纯摩擦材料,遵循基于Mohr-Coulomb破坏准则的理想弹塑性本构关系。首先,对圆形浅基础的竖向承载力进行了有限元计算, 并与滑移线解法进行了对比,两种方法所得结果比较吻合。进而探讨了砂土内摩擦角对于基础在V-H、V-M荷载平面与V-H-M三维荷载空间内的破坏包络轨迹的影响。计算结果表明,与不排水情况下软黏土地基上基础破坏包络面相比,砂土地基上圆形浅基础的破坏包络面形状有较大差异, 但V-H和V-M平面内的破坏包络面形状仍具有较好的归一化特性。基于有限元计算结果,建立了圆形浅基础在V-H-M三维荷载空间内的破坏包络面方程, 该方程可用来合理评价复合加载条件下砂土地基上圆形浅基础的整体稳定性。 相似文献
6.
根据瞬变电磁场理论公式中的响应和自变量之间的关系特点,提出用非线性方程模式的BP神经网络求解电阻率。通过构造单输入单输出网络结构,建立以不同时间点上的电流归一化的感应电压值为输入、视电阻率值为输出的神经网络,来拟合瞬变电磁场的二次涡流曲线。利用数值方法计算出的数据验证该训练网络的精确性,比较了不同算法对训练精度和收敛速度产生的影响。以重庆大学某处的防空洞探测实验为例验证了该算法的有效性,该算法避开具体的复杂电磁场计算或数值反问题计算,从而实现电阻率快速计算,为快速成像准备必要条件。 相似文献
7.
介绍了斜缀管式和平缀管式等截面钢管混凝土格构柱骨架曲线的计算方法并进行评价分析。研究表明,不同缀管布置形式的钢管混凝土格构柱,其抗震性能具有共性。借鉴钢管混凝土单肢柱的计算框架,开展等截面钢管混凝土格构柱骨架曲线的统一算法研究,对弹性刚度、水平峰值荷载、峰值荷载位移、下降段刚度等主要参数的计算方法进行了深入探讨和算例分析,并以干海子大桥格构柱墩为研究对象,采用OpenSEES有限元程序,对骨架曲线算法进行工程实例验证。研究结果表明,计算值与试验值及有限元计算结果均吻合良好。最后提出了适合工程应用的等截面钢管混凝土格构柱骨架曲线的统一简化算法,为钢管混凝土计算理论的进一步完善和规程编撰提供参考。 相似文献
8.
输电钢管塔空间KK型管板连接节点极限承载力 总被引：1，自引：0，他引：1
空间KK型管板连接节点作为输电钢管塔中最主要的节点型式,其安全性是整个塔架结构安全的重要保证。相比较于平面K型节点,在考虑实际结构中节点空间效应后的KK型节点的受力性能更为复杂。在平面K型管板节点的试验研究基础上,对两类空间KK型管板节点展开参数化分析,重点讨论了节点几何尺寸参数和主管轴压应力比等因素对节点极限承载力的影响变化规律。结合大量有限元参数分析所得计算结果,并综合考虑各种因素对节点极限承载力的影响,提出了空间KK型管板连接节点在主管管壁局部屈曲破坏模式下的极限承载力建议计算方法。 相似文献
9.
考虑实际结构易受荷载、环境温度和测试噪声等不确定性因素的影响,笔者基于区间分析原理提出框架结构不确定性损伤识别方法。利用测试的结构加速度响应数据,建立向量自回归模型,并采用其系数矩阵主对角线的马氏距离作为损伤特征指标。基于粒子群算法建立区间优化求解方法,并与传统的区间组合法和区间叠加法对比。通过提出的区间重叠率指标和区间名义值分别实现损伤定位和损伤程度的识别。数值模拟和实验室框架结构试验结果表明,区间分析能在测试数据较少时实现损伤识别,为损伤识别在实际结构中的应用提供了理论基础和技术手段。 相似文献
10.
LIM (LIN11, Isl1和MEC3)可参与细胞骨架构建、代谢调控以及生物和非生物胁迫等多种生命过程,是真核生物谱系中普遍存在的重要转录因子之一。为深入了解核桃LIM基因家族信息,本研究从核桃全基因组数据库中最终筛选确定了15个LIM基因,利用生物信息学方法对核桃LIM家族进行系统分析。结果表明,15个核桃LIM基因,其氨基酸序列长度介于189～577 aa,理论等电点介于5.56～9.08,分子量介于20.80～65.85 k D,均为疏水性蛋白,主要位于细胞核和叶绿体中,根据进化分析将其分为5个亚族。启动子区顺式作用元件分析表明,该基因家族成员受脱落酸、乙烯、茉莉酸甲酯和水杨酸4种激素调节,并能响应低温逆境。本研究基于核桃全基因组分析,鉴定出15个LIM基因家族成员,系统分析了理化性质、基因结构、染色体定位及顺式作用元件,为进一步探索核桃LIM基因家族在核桃树体响应逆境胁迫的生物学功能提供了参考依据。 相似文献
11.
The connections of frame structure elements at a node are ofen an elastic connection between hinged and rigid.In this paper,the stiffness matrix and the loading transfer matrix of frame element with turn elastic connections is deduced,the cross shear effect has been taken into consideration simultaneously.The stiffness matrices of some bar elements,such as both ends of the bar are hinged or rigid and one end is hinged but the other is rigid,are special cases of the stiffness matrices presented in this paper.After pointing out that the elastic coefficient at a node of a bar element with elastic joint is really a fuzzy quantity,the fuzzy stiffness matrix of the bar element is obtained,and a solution to structural fuzzy finite element equilibrium equations is presented.The fuzzy solution obtained from above is not only containing the solution of ordinary finite element method but also providing some additional informations with practical value.[WT5HZ] 相似文献
12.
In order to decrease the manufacture cost of all-terrain vehicles rapidly and effectively,a finite element model for the frame structure of all-terrain vehicles is built by using pre-processing software HyperMesh. The correctness of the model is verified by computing the freedom mode of all-terrain vehicles with Optisturct solver and contrasting it with existing test results. Through applying Optistruct solver and Fatigue to analyze stress distribution,deform and fatigue life of the frame under multi-conditions,and combining with sensitivity analysis results,the lightweight project of the frame is put forward. The validity of this lightweight project is identified after analyzing the optimized frame structure intensity and the fatigue life. The lightweight result show that the frame structure is lightened 6.6063 kg. At the same time,it shows that the structure optimization efficiency and the lightweight effect are enhanced by sensitivity analysis. 相似文献
13.
The iterative Lanczos-reduce method for sensitivity analysis, the Guyan condensed method and the iterative synchronous vector methods in finite element modal are studied in order to solve the dynamic characteristic of complicated machine system. The primary reasons influenced on calculation precision are pointed out. The principia of master freedom for Guyan condensed method are put forward. The calculation precision of three methods is compared with the same standard finite element model. The iterative Lanczos-reduce method for sensitivity analysis is proved to be optimum analysis and the eigenvalue of arm in work device of hydraulic excavator in finite element model is solved with iterative Lanczos-reduce method for sensitivity analysis. The theory basis is provided for reasonable choose to solve the dynamic of complicated machine structure. 相似文献
14.
Zhang Hua Zhang XiangWei Liao LinCan Ni Lin 《保鲜与加工》1998,(6):23-28
A dynamic explicit finite element method is used to pipe bend forming processes on bender in this paper.The degenerated shell element and co-rotational coordinate system are employed.The material of pipe is assumed to satisfy Hill's anisotropic elasto-plastic yield condition.The bend die and press die are assumed as rigid surfaces and the contact force is computed by penalty method.Several numerical examples are given.They show that this method is effective. 相似文献
15.
植物根系固土作用模型研究进展 总被引：2，自引：0，他引：2
植物根系固土作用模型研究已历经近40年,从简单的极限平衡模型到复杂的有限元和离散元数值模型,已发展到10余种。总结这些根系固土作用模型不仅对揭示根系加固土壤作用的力学机制和分析林地边坡的稳定性具有重要意义,对根系固土作用模型未来的研究方向也具有积极指导意义。笔者对根系固土作用模型分2部分进行综述,第一部分主要介绍根系固土作用的理论模型,包括：Wu模型、倾斜根系模型、位移模型、纤维束模型、根束增强模型和能量模型,以及这些模型的应用条件、模型优缺点、适用范围等。第二部分主要综述根系固土作用的数值模型,包括：有限元数值模型、离散元数值模型和造林边坡稳定性分析数值模型,并详细比较了有限元与离散元数值模型的优缺点和在造林边坡稳定性分析上的应用。最后探讨了目前根系固土作用模型研究中存在的不足以及未来的发展方向。 相似文献
16.
The analytic method for the free vibration of plane frame structure is presented. It is achieved by transforming the general eigenvalue problem of natural frequency and vibration mode of continuously distributed property system into typical boundary value problem of ordinary differential equation (ODE). A series of ODE, corresponding to the general eigenvalue problem, is formed, and then is solved by an general ordinary differential equation solver-COLSYS. Each component of a frame structure is regarded as an element in the analytic method. This makes it more efficient than that of finite element method which needs to increase elements to get the value of high-class natural frequency and vibration mode accurately. Some applications of the method show that it can solve the free bending vibration of plane-frame structure with various types of displacement constraint. The result indicates that this method is precise and efficient. 相似文献
17.
In order to reflect the stochastic characteristic of a structure more completely and accurately,this paper presents a theory and method of modeling with structural stochastic parameters using probabilistic finite element method and perturbant finite element method,on the basis of modeling with deterministic parameters.It is applied to double decker space frame,good results are gained. 相似文献
18.
The design method of parameter optimization of nonlinear viscous dampers for dissipation structure was analyzed based on response surface methods. The method included experimental design, finite element analysis, fitting the response surface function and parameter optimization. Taking a reinforced concrete frame structure for an instance, the mathematical model of parameter optimization of viscous dampers for dissipation structure was established by taking the minimum all damping force as objective function and taking the interlayer maximum displacement less than limits as constraints, and then the damper parameters were optimized using the method of nonlinear programming optimization. The results show that the method of parameter optimization of viscous dampers based on response surface method can ensure the structural displacement is less than limit and the construction cost can be reduced. 相似文献
19.
RONG Guo-rui 《保鲜与加工》2000,(4):50-55
In this paper, the formulas calculating the stress of frame of truck crane are deduced according to the thin wall structure theory, the calculation program is compiled and used in calculating the stress of the truck frame. The calculated results are checked and complemented by structural analysis program with finite element SAP5, providing the theoretical and calculation basis for design and calculation of the frame. 相似文献
20.
How to select automatically the disposition of steel bar in a computer aided design(CAD)system for reinforced concrete frame structure is aproblem relatedt ot he practicality and increasing capacity of the CAD system.This paper suggests a practical method for selecting steel bar of beam in framestructure with the application of knowledge and experience of the experts forreasoning and judging.The method is convenient for calculation.The results ofcalculation are in agreement with detailing requirement and usual engineeringpractice.The method has great practical value. 相似文献