【摘 要】
:
A significant negative aspect in the operation of bridge-type cranes are the technical problems associated with wear of the wheels and the crane track,which causes crane skewing.The main causes of crane skewing include unevenness of the crane track,unequa
【机 构】
:
VSB-Technical university of Ostrava,Faculty of mechanical Engineering,Institute of Transport,17.list
论文部分内容阅读
A significant negative aspect in the operation of bridge-type cranes are the technical problems associated with wear of the wheels and the crane track,which causes crane skewing.The main causes of crane skewing include unevenness of the crane track,unequal loading of the traction drives depending on the position of the crane trolley,slips and different sizes of travel wheels and combinations of these causes.Firstly,this paper presents a design solution that can be used to detect the magnitude of mechanical stress and deformation of the steel structure of the crane,caused by the effects of skewing.The me-chanical stress generated by the transverse forces of the deformed geometric shape of the crane bridge structure is recorded by mechanical stress detectors installed in the inner corners of the crane bridge.The resulting electrical signal from element mechanical voltage detectors,loaded by axial forces,can be used for feedback control of separate crane travel drives controlled by frequency converters.Secondly,this paper presents the calculation of the lateral transverse forces according to CSN 270103 and the de-termination of the values of mechanical stresses of the deformed steel structure of the crane bridge of a two-girder bridge crane using the finite element method in the program MSC.MARC 2019.Finally,this paper presents the structural and strength design of mechanical stress detectors and the conclusions of laboratory tests of axial force loading of mechanical stress detectors on the test equipment.At the same time,it presents records of the measured axial forces acting in the mechanical stress detectors,arising from the deformation and warping of the crane bridge by the known magnitude of the axial force acting on the crossbeam and from the deformation of the crane bridge caused by the crane operating modes.
其他文献
Metals have been mankind\'s most essential materials for thousands of years.In recent years,however,innovation-driven development of major national security strategy and core areas of the national econ-omy is highly impeded by a shortage of advanced hig
Recently proposed clustering-based methods provide an efficient way for homogenizing heterogeneous materials,yet without concerning the detailed distribution of the mechanical responses.With coarse fields of the clustering-based methods as an initial gues
推移质泥沙颗粒的跃移是河流泥沙运动的重要形式.为了研究推移质颗粒跃移运动参数的变化规律,在水槽试验中采用高速摄像技术,观测7种工况条件下,0.3~1.7 mm粒径的推移质颗粒的跃移运动形态,提取颗粒跃移运动的时空信息,分析了泥沙颗粒跃移距离和跃移高度的变化规律.结果 表明,相对跃移高度和相对跃移距离的概率密度分布函数均服从Γ分布,对比前人的试验结果发现,4组试验颗粒的相对跃移距离概率分布的峰值提前,而其他3组试验结果的峰值几乎同时出现.试验值与韩其为公式的计算值基本符合,验证了理论计算值的合理性和可靠性.
The present study provides a three-dimensional volume-of-fluid method based on the adaptive mesh refinement technique.The projection method on the adaptive mesh is introduced for solving the incom-pressible Navier-Stokes equations.The octree structure mes
The actuator disc method is an engineering approach to reduce computer resources in computational fluid dynamics (CFD) simulations of helicopter rotors or aeroplane propellers.Implementation of an ac-tuator disc based on rotor circulation distribution all
Transfer printing based on switchable adhesive is essential for developing unconventional systems,in-cluding flexible electronics,stretchable electronics,and micro light-emitting diode (LED) displays.Here we report a design of switchable dry adhesive base
The coupling effect between a pulsating bubble and a free surface near a rigid structure is a compli-cated physical process.In this study,the evolution of an underwater explosion bubble and the free sur-face near a rigid structure is modeled by the bounda
This study analyzes the function of different muscles during arm wrestling and proposes a method to analyze the optimal forearm angle for professional arm wrestlers.We built a professional arm-wrestling platform to measure the shape and deformation of the
完善水沙调控体系是应对黄河水少沙多、水沙关系不协调的关键措施.结合实测资料,计算了河道输沙能力,分析了水沙调控体系运行机制,计算了水沙调控体系对黄河水沙关系的调节作用,结果表明:河道输沙效率随着水流流量的增大而增大,且在平滩流量附近存在明显的拐点,骨干水库群联合调控可泄放接近下游河道最小平滩流量的大流量过程,提高河道输沙能力,减轻河道淤积.当黄河来沙8亿t,水库群拦沙期内通过拦沙和调水调沙,进入下游的水沙关系协调度小于1,水沙关系是协调的;正常运用期通过调水调沙可改善黄河水沙关系的不协调程度.与现状工程条
基于VOF法的RNG k-ε双方程紊流数学模型,对阶梯溢洪道水流压强特性及下游局部冲刷坑的形态和发展进行了三维数值模拟.结果 表明:数值模拟结果与试验值吻合良好;台阶面流速沿着台阶凸角的连线形成一个“伪底”,流速与坡面近似平行,各个台阶与主流之间存在一个三角形空腔,形成顺时针旋转的漩涡.漩涡中心速度趋近于零,向外逐渐增大,水流表面的流速为最大值.阶梯立面靠近凸角处产生最小压强值,在阶梯水平面从凹角到凸角压强先增大,增大至最大值后又减小.计算了下游冲刷坑的范围及最大冲刷深度,定量给出了冲刷坑最深点流速与冲刷