液压隔膜泵用环状U型隔膜挠曲变形分析

为了建立新型液压隔膜泵用环状U型隔膜基础理论体系和设计方法,借助Ansys有限元分析软件的非线性分析工具,对其挠曲变形与变形量的关系进行了分析.以液压隔膜泵样机用环状U型隔膜为物理模型,建立了具有几何和材料双重非线性特性的环状U型隔膜的薄壁中空双层壳体有限元模型;在工作范围内,对模型固定支撑端施加固定约束,运动支撑端施加位移约束,内外表面施加面载荷,分析了模型在不同压缩、拉伸位移载荷下的挠曲变形;应用差分进化算法对环状U型隔膜挠曲变形的位移数据进行曲线拟合,通过控制均方差、相关系数和决定系数等判断标准,反复修正拟合曲线,总结了其挠曲边线的运动规律,获得了其挠曲变形曲线的等效解析解,推导了其工作容积理论计算公式;通过工程实例计算,验证了工作容积理论计算公式的可行性,为形成液压隔膜泵用环状U型隔膜工作机理及隔膜结构和优化设计方法提供了理论基础.     

Determination Method and Criterion for Voids by Dynamic Deflection Difference in the Same Cement Slab

Aiming at the lack of the current determination method for voids in practical engineering applications, in order to accurately quantify the voids beneath cement slab, the determination method was proposed with slab edge slab center deflection difference and slab corner slab center deflection difference in the same cement slab for voids.Three dimensional models were set up using the ANSYS finite element method for voids beneath slab corner and slab edge.And the load was simulated with FWD test results.Thereafter, the deflection values were calculated in slab center, slab corner, slab edge under different void depth, void area and load transfer capacity.And the range of deflection diffidence was obtained.With Yantai Weihai expressway, detection data for deflection using Falling Weight Deflectometer were statistically analyzed.And the criteria and correction factors of load transfer capacity were given with simulation and samples analysis.The feasibility of criteria was verified by actual test data.It is found that the simulation values and the test values are in good agreement.The accuracy of void determination by lab edge slab center deflection difference and slab corner slab center deflection difference are 88.5% and 84.6%, respectively, which meet the engineering requirements.The voids were determined under the same conditions with the elimination of deflection variability.     

Theoretical Analysis and Finite Element Computing for Rectangular Plates Bucking under Shear Load

By adopting the energy and finite-element methods with analysis software MATLAB and ANSYS,a detailed and complete solution process for bucking of simply supported rectangular elastic plates is provided.By increasing the triangular series for the deflection function,the amendments have been made to the K values given in references.Through finite element analysis,the expression of K value is fitted out.It is ascertained that the shear stress,taken as a critical shear stress,is reasonable according to the small deflection theory under limited plate deflection.The results of two analytical methods show that the fitting curve of K values used by finite element analysis has more comprehensive practical significance.     

Rapid Assessment of Load-Bearing Capacity About Simple-SupportedGirder Bridge Based on Dynamic Test instead of Static Loading Test

The relation between the deflection check coefficient (ηy) of mid-span and first vertical flexural frequency check coefficient (ηf) was established based on theory of the uniform cross-section simple-supported beam. The variation and difference between the ηy and 1/η2f of a simple-supported six girder bridge were researched by simulation under these situations: change of the bearing stiffness; change of the boundary conditions; the floor system enhanced the structural stiffness; local damage of the superstructure. The static loading test and dynamic characteristic test of two fabricated simple-supported T girder bridges were taken to get the measured ηy and 1/η2f. Simulation and experimental results show that 1/η2f can instead ηy to reflect the structural stiffness of the simple-supported girder bridge and rapid assess its load-bearing capacity.     

简述路面弯沉的测试

本文作者详细介绍了4种弯沉测试技术及测试原理、技术特点、弯沉数据的修正及其评定。     

小型堆垛起重机教学实验平台的设计

提出了一种小型堆垛起重机教学实验平台的设计方法,介绍了小型堆垛起重机的总体结构和主要技术参数,并对其关键部件的设计做了详细阐述,主要包括水平行走机构、机架、升降机构、载货台和货叉的设计;最后计算货叉工作时的变形量和挠度,同时也对机架的立柱和横梁的挠度进行校核。经计算验证得知,小型堆垛起重机的货叉以及机架的挠度都在安全使用范围之内,完全满足使用要求。该自制教学实验平台对研究教学型堆垛机的开发设计和完善高校教学设备有着良好的推动和借鉴作用。     

昆明南三环立交跨线桥桥梁主体结构试验研究

结合昆明市南三环路口立交跨线桥工程建设实际，详细介绍桥梁荷载的检测方法，即通过桥跨结构跨中截面应变及挠度的测试，对桥跨结构在试验荷载作用下的实际受力状态和工作状态进行系统分析，进而对该桥梁主体结构的工作性能作出评价，为桥梁竣工验收提供技术依据。     

竹碎料——木纤维复合板弯曲挠度特性的研究

该文对两边简支、两边自由时的竹碎料--木纤维复合板的弯曲挠度特性进行了研究，并构建了它的挠度函数模型。结果表明:①挠度函数与板的载荷状态、平面尺寸及板内任一点的坐标有关。②当复合板在外力作用下产生弯曲挠度变形时，板内任一点的挠度与外力之间具有线性关系。③复合板上下表面对应处的挠度值基本相等，而且实测结果和理论计算结果之间的误差最小为1.3%，最大为11.7%，平均为5.87%， 说明模型具有很好的拟合性。      

多层砌体1/4比例模型墙体顶部裂缝试验研究

为了研究多层砌体结构房屋顶端裂缝问题, 根据简单相似性原理构建了一1∶4比例、每层均布有构造柱和圈梁的H型六层混凝土小型空心砌块砌体结构墙体模型.通过对墙体模型进行竖向加载的拟静力试验，模拟了纵横墙荷载差，深入研究了在竖向荷载差作用下砌体房屋顶端裂缝的产生行为和发展规律.研究结果表明：随着承重墙上竖向荷载的增加，承重墙与非承重墙之间的荷载差所引起墙体的竖向变形差增大，同时承重墙中部变形相对承重墙和非承重墙交界处变形较大.当荷载增加到一定值时，由于承重墙对非承重墙产生的拉应力进一步加大，承重墙上靠近非承重墙一端顶部出现裂缝.随着荷载的继续增加，承重墙上裂缝宽度增大并扩展，并有新的裂缝出现.由于构造柱-圈梁体系的约束作用，有效地控制了承重墙与 非承重墙之间的竖向变形差的增大.     

浅谈冲击碾压技术在公路路基处理中的应用

文章阐述了冲击碾压技术的冲击压实机理,通过冲击压实技术在某项目填方路基中的实际应用,介绍了冲击压实的施工工艺和冲击压实过程中应注意的事项,为今后工程中采用冲击压实技术提供借鉴.