纤维稳定土基层参数对路面力学响应的影响分析

为了分析聚丙烯纤维加筋水泥石灰土基层材料对路面结构设计及重载交通的影响,以聚丙烯纤维加筋水泥石灰土为对象,借助正交分析法,选取基层厚度、基层模量(聚丙烯纤维掺量)和底基层厚度作为主要影响因素,对聚丙烯纤维水泥石灰土基层沥青路面结构设计参数进行计算;同时分析了不同超载作用下纤维水泥石灰土基层沥青路面结构的弯沉及应力情况。结果表明:提高基层厚度有利于路面结构受力,同时使用聚丙烯纤维掺量为0.2%的水泥石灰土作基层材料,对于优化重载作用下的路面结构设计更为显著。为聚丙烯纤维加筋水泥石灰土在石料匮乏地区的应用提供了依据。

基于振动法的拉索索力测试研究

对拉索(吊杆)索力的测量方法展开了研究,通过建立拉索的有限元仿真模型,在考虑拉索锚固边界以及减振器的边界刚度影响的情况下,分析了拉索索力与多阶固有频率之间的关系,并拟合出拉索索力与多阶固有频率之间的理论公式。在拉索索力实际测量过程中,依据有限元分析得出的拉索多阶固有频率确定测量采样频率,再依据拉索的多阶理论自振振型确定测量采样方向,保证可采集到拉索单向振动的多阶固有频率,最后将拉索的实测多阶固有频率代入理论公式计算拉索的真实索力。该方法可大大提高振动法测量拉索索力的准确性和可靠性。

台阶式拱座基础的计算分析与探讨

对于台阶式拱座基础的地基应力计算,根据计算假定和精度要求的不同,主要有传统法、变形协调法和有限元数值分析法3种计算方法。基于某上承式钢筋混凝土拱桥的工程实例,对其中的变形协调法进行了适当的变换思考以适用于本工程,通过有限元数值分析法研究了地基应力沿基础背面和底面的分布情况,同时对3种计算方法的结果进行了比较分析,研究了地基刚度对地基应力的影响以及地基应力沿横桥向的分布规律。研究结论和建议可为类似工程的设计提供参考。

爆炸飞板碰撞厚钢板时背面的空气冲击波压力计算

在炸药爆炸驱动飞板碰撞厚钢板后 ,利用二维动态有限元数值分析方法对厚钢板自由面的速度进行了数值计算 .还利用钢板和空气界面条件对钢板背面空气中冲击波的传播进行了一维球对称的数值分析 。

对探针式同轴探头在骨肿瘤微波热疗中电磁场分布的数值模拟分析

目的 研究探针式热疗探头在骨肿瘤微波热疗中产生电磁场分布的模拟数值结果。方法 取分层柱状结构骨肿瘤模型 ,将同轴电缆剥掉外导体后构成探针式探头。采用有限元数值分析方法 ,对不同插入深度及不同尺寸的同轴探头在组织中产生的电磁场进行数值模拟计算。结果 当探头外导体的截断面处于组织内部时 ,辐射能量能较好地集中于被辐射组织中 ;当探头接近被辐射组织顶端但又不穿透时 ,可使顶端辐射增强。结论 热疗时探头不同的插入深度及规格 ,可使被辐射组织的电磁场发生相应变化 ,故在临床微波热疗操作中 ,应根据肿瘤大小。

Variation of hydraulic gradient in nonlinear finite strain consolidation

In the research field of ground water, hydraulic gradient is studied for decades. In the consolidation field, hydraulic gradient is yet to be investigated as an important hydraulic variable. So, the variation of hydraulic gradient in nonlinear finite strain consolidation was focused on in this work. Based on lab tests, the nonlinear compressibility and nonlinear permeability of Ningbo soft clay were obtained. Then, a strongly nonlinear governing equation was derived and it was solved with the finite element method.Afterwards, the numerical analysis was performed and it was verified with the existing experiment for Hong Kong marine clay. It can be found that the variation of hydraulic gradient is closely related to the magnitude of external load and the depth in soils. It is interesting that the absolute value of hydraulic gradient(AVHG) increases rapidly first and then decreases gradually after reaching the maximum at different depths of soils. Furthermore, the changing curves of AVHG can be roughly divided into five phases. This five-phase model can be employed to study the migration of pore water during consolidation.

Experimental and Numerical Investigations on Vibration Characteristics of a Loaded Ship Model

In this paper, the vibration characteristics of the structure in the finite fluid domain are analyzed using a coupled finite element method. The added mass matrix is calculated with finite element method （FEM） by 8-node acoustic fluid elements. The vibration characteristics of the structure in the finite fluid domain are calculated combining structure FEM mass matrix. By writing relevant programs, the numerical analysis on vibration characteristics of a submerged cantilever rectangular plate in finite fluid domain and loaded ship model is performed. A modal identification experiment for the loaded ship model in air and in water is conducted and the experiment results verify the reliability of the numerical analysis. The numerical method can be used for further research on vibration characteristics and acoustic radiation problems of the structure in the finite fluid domain.

Numerical Homogenization of the Elliptic Problem with Rapidly Varying Tensor or Boundary Condition

Homogenization is concerned with obtaining the average properties of a material. The problem on its own has no easy solution, except in cases like the periodic case, when it can be obtained in closed form. In this paper we consider a numerical solution of the elliptic homogenization problem for the case of rapidly varying tensor or boundary conditions. The method makes use of an adaptive finite element method to correctly capture the rapid change in the tensor or boundary condition. In the numerical experiments we vary the mesh size and do a posteriori error analysis on test problems.

Analysis of thin plates by the weak form quadrature element method

The recently proposed weak form quadrature element method （QEM） is applied to flexural and vibrational analysis of thin plates The integrals involved in the variational description of a thin plate are evaluated by an efficient numerical scheme and the par- tial derivatives at the integration sampling points are then approximated using differential quadrature analogs. Neither the grid pattern nor the number of nodes is fixed, being adjustable according to convergence need. The C~ continuity conditions char- acterizing the thin plate theory are discussed and the robustness of the weak form quadrature element for thin plates against shape distortion is examined. Examples are presented and comparisons with analytical solutions and the results of the finite element method are made to demonstrate the convergence and computational efficiency of the weak form quadrature element method. It is shown that the present formulation is applicable to thin plates with varying thickness as well as uniform plates.

The Settlement Characteristic of Underground Urban Complex in Shanghai

The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex which was located in Shanghai. The effects on water pressure and building settlements were analyzed as well. The numerical analyses by finite element method (FEM) were conducted. It showed that the soil under the excavation base continued to heave during the following certain construction stage. It also found that the bearing capacity of uplift piles which supported the buildings affected the structure quality significantly. The conclusions can be applied in future projects.

A novel high birefringence equal diameter circular-hole photonic crystal fiber

A novel equal diameter circular-hole photonic crystal fiber(PCF) with high birefringence is proposed and numerically analyzed by employing the finite-element method. The proposed PCF's birefringence is 10^(-3), which can reach 2 orders higher than that of traditional high birefringence fiber, and this equal diameter circular-hole structure reduces the difficulty of the actual drawing process. The effect of different parameters on the birefringence of this PCF is investigated, and the application of the Sagnac interferometer based on fiber filling technology in temperature sensing is studied. The result shows that the high birefringence PCF can be used in both optical communication and optical sensing fields.