平衡重式叉车倾翻预警方案研究

对平衡重式叉车满载堆垛纵向、满载运行纵向、满载堆垛横向、空载运行横向4种工况的稳定性进行分析,得出叉车稳定性的重心距极限条件。对叉车受力模型进行分析,把稳定性的重心距极限条件转化为更容易实时测量的受力临界条件,根据受力倾翻临界条件设计叉车倾翻预警方案,该方案具有实时性和可操作性。     

平衡重式叉车倾翻预警方案研究

对平衡重式叉车满载堆垛纵向、满载运行纵向、满载堆垛横向、空载运行横向4种工况的稳定性进行分析，得出叉车稳定性的重心距极限条件。对叉车受力模型进行分析，把稳定性的重心距极限条件转化为更容易实时测量的受力临界条件，根据受力倾翻临界条件设计叉车倾翻预警方案，该方案具有实时性和可操作性。     

铰接式车辆转向时的横向稳定性分析

一、理论分析铰接式车辆转向时横向稳定性发生变化,可能造成车辆倾翻,所以需要进行研究。现有的计算方法有所谓“一级失稳”和“二级失稳”,并用稳定度来计算。其根据是认为铰     

工程机械稳定性分析与计算

工程机械稳定性分析与计算徐州工程机械制造厂研究所万汉驰机器的稳定性是指机器在各种可能工况下不发生滑移和倾翻而保持正常工作状态的性能，一般用滑移角和倾翻角来评价，是一种安全性指标，在整机的结构布置与设计中是应该优先考虑和保证的。机器稳定性包括平地上的稳...     

ROPS/TOPS-SYT-3-200型滚翻/倾翻保护结构试验台

为满足土方机械司机保护结构检测需要,成功研制ROP S/TOP S-S YT-3-200型滚翻/倾翻保护结构试验台。该试验台的竖直加载装置、侧向加载装置和纵向加载装置均能够横向或纵向移动,快速对正滚翻和倾翻保护装置的加载位置;采用高平顺性高压伺服液压缸加载,能够精确控制加载载荷;加载液压缸内安放位移传感器,加载液压缸端部安装测力传感器,可自动采集、存储加载力以及滚翻和倾翻保护装置的位移值,并实时自动计算与存储加载的能量值。     

动臂塔式起重机臂架防倾翻装置设计计算

介绍了动臂式塔式起重机防倾翻装置种类,从动态能量角度分析防倾翻装置的设计计算问题,提出一种防倾翻装置动态的设计计算方法,为今后防倾翻装置的设计提供一定的参考依据。     

铰接式轮胎装载机倾翻载荷的计算方法

在进行装载机设计时,有必要对整机倾翻载荷进行计算,以保证整机额定工作载荷达到设计要求.倾翻载荷是衡量装载机稳定性的一个重要指标,同时也是确定整机额定工作载荷的主要依据之一.介绍了铰接式轮胎装载机倾翻载荷的计算方法,为方便计算,将装载机划分为前车及后车两部分,两个部分的划分以铰接中心为界限,具体的步骤为:首先估算前车及后车的质量及重心位置,然后对整机操作质量及车架对直状态的倾翻载荷进行计算,最后计算车架最大偏转状态下的倾翻载荷.介绍的计算方法和步骤可供装载机设计者参考.     

装载机横向一级稳定性计算

评价装载机稳定性时有两种工况:一是位于水平路面上的装载机在外载荷作用下抗倾翻性能,用失稳比(倾翻力矩与稳定力矩之比)作为评价指标。例如轮式装载机纵向失稳比应小于或等于50％。二是装载机在倾     

浅议塔机抗倾翻稳定性校核的载荷系数

1 问题的提出在塔机设计中,抗倾翻稳定性校核是不容忽视的一个重要内容。然而在不同的标准中规定的抗倾翻稳定性校核的载荷系数是不同的。究竟采用那一种载荷系数更加先进合理,更加经济且又能保证安全可靠是我们在制定新的设计规范,进行塔机抗倾翻稳定性校核时亟待解决的问题。本文通过对四川建筑机械厂生产的几种塔机,按不同的标准进行计算的对比数据提出自己的看法。     

大跨度大吨位型钢转换桁架高空滑移提升技术

结合新疆某工程介绍了大跨度、大吨位型钢转换桁架在普通大型机械无法作业情况下,高空利用桁架对称特性,自承载式分块滑移和提升完成桁架吊装.即横向桁架作为滑移支架,纵向桁架分块在横向桁架上滑移,然后利用就位的纵向桁架柱作为支撑点,在柱顶设置钢绞线千斤顶,利用固定在纵向桁架两侧柱顶的钢绞线千斤顶将纵向桁架提升至设计高度,完成桁架吊装.     

A new method to evaluate roadheader operational stability

Roadheader, one of the mechanized excavation equipments, has an exceptional place among the other excavation methods. Determination of the stability states of the roadheader is an important matter for the efficiency of excavation. For this reason, a new method has been developed to obtain numerical values that indicate stability states of such machines. The method has been developed for both longitudinal and transverse cutting head type machines by establishing stability equations for states of turning around the vertical axis, turning to the side direction, turning to the back direction and sliding in all cutting modes. A computer program based on these equations has been written in C++ programming language. The stability analysis can be made either for one point on the excavation face or whole face. Obtained values can be used to compare the stability states of various roadheaders in the same cutting condition as well as using to compare the stability states of a roadheader. A stability index that has also been established can only be used to compare a stability state of a roadheader in different cutting conditions. The developed methodology was tested in a transverse cutting head type roadheader for arcing, lowering and lifting modes. It has been obtained that the stability state of turning around the vertical axis of the roadheader is the most critical state especially in arcing mode. The effects of the machine design parameters, cutting head and tunnel parameters on the stability of the roadheaders can also be investigated by this method.     

Influence of longitudinal and transverse members on geogrid pullout behavior during deformation

A series of pullout tests were carried out by using a highly extensible geogrid with the different longitudinal member and transverse member ratios to investigate the influence of the longitudinal and transverse members of a highly extensible geogrid on the pullout behavior. From the results, the following were made clear: the mobilization of bond stress depends on the strain of the geogrid; the influence zones of longitudinal members become isolated with the increase of the longitudinal member spacing; the mobilization of transverse member resistance depends on the displacement of the geogrid at the location of that transverse member; and the contribution of longitudinal members to the pullout force is more significant than that of transverse members during the deformation stage in the case of the highly extensible geogrid, since large elongation occurs in the geogrid, which restricts the mobilization of the full effect of transverse members. Furthermore, the mobilization mechanisms of the longitudinal member and transverse member effects are discussed.     

隧道横纵向通道组合模式下的人员疏散特性

针对城市隧道横纵向通道组合疏散方式,使用Pathfinder疏散模拟软件搭建疏散模型,计算得到疏散运动时间、各通道占用时间。并结合现场试验,分析较大通过能力的横通道对附近疏散滑梯/楼梯的影响,进一步探索不同疏散模式给人员疏散带来的影响变化。研究表明：与横向疏散相比,横纵向结合的疏散方式可以在保证疏散效率的同时,增大横通道间距,减少施工风险和成本;相比仅设置纵向疏散,增设横通道后可使大部分场景下的疏散时间缩短,且横纵向结合疏散对特殊人群更加友好,具有更强的人员疏散普适性;疏散人员附近各通道的通过能力差异会影响人员对通道的倾向性,导致通道占用时间的差异,可采用应急广播等方式进行疏散引导。     

广义的盾构隧道纵向等效连续化模型研究

 在传统纵向等效连续化模型基础上,考虑横向刚度的影响及纵向环缝影响范围,提出广义的盾构隧道纵向等效连续化模型。以耀华支路磁浮盾构隧道为工程背景,分析得到隧道纵向刚度有效率随横向刚度和环缝影响范围的变化规律。结果表明,随横向刚度减小,截面受压区面积增大,隧道纵向等效刚度有效率减小;随环缝影响范围的增大,纵向等效刚度有效率减小。传统纵向等效连续化模型和修正的纵向等效连续化模型可以看作是该模型的特例。研究结果对盾构隧道纵向稳定性分析具有一定参考价值。     

The effect of machine design parameters on the stability of a roadheader

A “roadheader” excavator has a special set of characteristics among tunnel excavation machines and the determination of the stability states of a roadheader is important for effective and continuous excavation. For roadheaders having equal power, if one is more stable than another, it can respond to higher boom forces. A new computer program was developed to analyze the stability states of roadheaders. The developed method allows analysis for both longitudinal and transverse cutting head type machines either at one point on the excavation face or in terms of the whole face. Values of the four stability states of the roadheader, namely: turning around the vertical axis, turning to the side directions, turning to the back direction and sliding, can be obtained using this program. In this study, the effects of machine design parameters were investigated by applying this method to the stability of a longitudinal type roadheader. The studied machine design parameters are the machine weight, boom length, machine width, track width, distance between the back leg of the machine and the center of gravity, distance between the start of the boom and the center of gravity, distance between the horizontal point and the vertical rotation point of the boom, and the distance between the ground and boom axis when it is parallel to the ground. The effect of the machine design parameters on stability has been illustrated in detail.     

CFRP与钢板的粘结性能研究

进行了CFRP与钢板的粘结性能试验研究，以期了解2种材料的粘结性能以及底胶和横向CFRP等因素对试件承载力和刚度的影响。研究结果表明：在纵向CFRP断裂前：不论是否使用底胶以及是否粘贴横向碳纤维织物，纵向CFRP和钢板都能保持协同工作；试件的荷载一应变曲线可以划分为3个阶段，即弹性阶段、弹塑性阶段和下降段；在其它条件相同的情况下，底胶和横向CFRP对试件的承载力和刚度并无显著影响。     

考虑箍筋和横肋影响的现浇圆筒芯空心楼盖受剪性能试验研究

为研究现浇圆筒芯空心楼盖的受弯和受剪性能,进行了2组共6个试件的试验。通过荷载-挠度曲线的比较,研究了截面空心率和横肋对空心板弯曲性能的影响。根据实测板端受剪承载力的对比和实测箍筋应变的分析,研究了横肋对横孔板受剪承载力的影响,以及顺筒肋箍筋对顺孔板和横孔板受剪承载力的不同作用机理。研究表明,横肋有助于改善横孔板的弯曲性能,当截面空心率低于45%时横孔板与相应顺孔板的受弯性能基本相同。横肋弥补了通孔横孔板在剪力传递机理上的缺陷,能显著提高横孔板的受剪承载力。顺筒肋中的箍筋对横孔板的受剪承载力贡献极小,可忽略不计。同时依据试验结果,提出了考虑箍筋和横肋影响的受剪承载力计算方法。     

Longitudinal shear test on steel-concrete composite beam with two rows of shear studs

为研究带双排栓钉的组合梁的纵向受剪性能,进行了7个带双排栓钉的钢-混凝土组合梁试件和1个带单排栓钉的钢-混凝土组合梁对比试件的纵向受剪试验。研究栓钉横向或纵向间距、横向配筋率、混凝土强度、栓钉排布方式等因素对带双排栓钉的钢-混凝土组合梁纵向受剪性能和混凝土板破坏形态的影响,并分析了各研究参数对峰值荷载和极限滑移量的影响。结果表明：带双排栓钉的钢-混凝土组合梁试件破坏模式主要表现为“八”字形裂缝的剪切破坏;栓钉横向、纵向间距、混凝土强度以及混凝土板配筋率是影响钢-混凝土组合梁受剪承载力的主要因素;受剪承载力均随着栓钉横向间距、纵向间距、混凝土强度以及混凝土板的横向配筋率的增加而增大。     

奥氏体型S30408不锈钢角焊缝连接拉伸试验研究

为研究奥氏体型S30408不锈钢角焊缝连接接头的承载性能,对6个正面角焊缝连接试件和5个侧面角焊缝连接试件进行了拉伸试验,测得焊缝连接试件在拉伸作用下的极限荷载,以及焊缝强度、焊缝随荷载的变形情况,并对焊缝的破坏状态进行了观察。试验结果表明：正面角焊缝连接接头焊缝断裂面呈底部垂直于芯板表面而上部接近30°斜截面的不规则撕裂状,其抗拉强度平均值742 MPa,焊缝平均变形量为2 875 mm。侧面角焊缝连接接头焊缝断裂面较为平整,接近45°理论值,其剪切强度平均为506 MPa,焊缝平均变形量为4 387 mm。正面角焊缝连接试件焊缝抗拉强度为侧面角焊缝连接试件剪切强度的1.47倍。正面角焊缝和侧面角焊缝连接试件承载力试验值均高于CECS 410:2015《不锈钢结构技术规程》和欧洲规范Eurocode 3的设计值,CECS 410:2015规程中对于正面角焊缝和侧面角焊缝连接试件承载力设计值的规定过于保守;欧洲规范Eurocode 3对正面角焊缝连接试件承载力设计值的规定也较为保守,而对侧面角焊缝连接试件承载力设计值的规定较为合理。     

考虑横向性能的盾构隧道纵向等效刚度分析

盾构隧道作为一个三维问题,其横向性能与纵向性能是密切联系的,将其横向和纵向割裂为两个平面问题,虽然可使问题简单化,但无法考虑纵横向性能的匹配关系。在横向修正惯用法的基础上,将横向弯曲刚度有效率引入到纵向等效连续化模型的推导中,对考虑横向刚度影响的盾构隧道纵向等效抗弯刚度进行理论推导,得到了考虑横向刚度有效率的纵向等效抗弯刚度计算式,从而初步将纵向刚度的分析与横向刚度的变化统一起来,进而也说明了盾构隧道纵、横向抗弯刚度的相关性和匹配性。实例分析表明：盾构隧道横向抗弯刚度的大小与纵向等效抗弯刚度关系密切,表现为同方向、近线性关系变化,即纵向抗弯刚度随横向抗弯刚度的增大而增大。