Boom Box爆炸机IC32失效原因探析

Boom Box爆炸机IC32的失效率明显高于其它器件。本文从IC32在印刷电路板的位置特征着手,对IC32的失效模式、失效机理、爆炸工的操作程序等多个方面进行了分析,找出了其失效的根本原因,并提出了纠正措施,以防止失效的再发生。     

邕宁蒲庙大桥吊杆更换施工技术

该文介新型组合式挤压拉索构造及在蒲庙大桥中的应用,全桥吊杆更换的施工方法。通过移动式兜吊系统采用的使用,使得吊杆更换施工更安全、便捷,施工速度显著提高。该法为国内首创。     

斗轮挖掘机臂架结构抗震分析

利用SRSS法进行地震组合 ,推导了斗轮挖掘机臂架在考虑局部效应时的地震应力和位移的计算公式 ,通过计算及对比分析发现 ,在对大型杆系结构进行抗震分析时 ,必须考虑局部效应。     

Chemo–mechanical interactions in clay: a correlation between clay mineralogy and Atterberg limits

Among some few others tests, the evaluation of the Atterberg limits is a very basic soil mechanical test allowing a first insight into the chemical reactivity of clays. Basically, the liquid limit and the plasticity index are highly and mainly influenced by the ability of clay minerals to interact with liquids. In this contribution, a correlation between the Atterberg limits and clay mineralogy is proposed. This correlation increases the understanding between clay mineralogists and engineers in soil mechanics; additionally a wealth of information in clay mineralogy literature is now available to predict the mechanical behaviour of clays via index tests.     

混凝土泵车浇筑过程机器人化探讨

对混凝土泵车布料机构的运动姿态调整采取了最优控制 ,解决了泵车机器人化的运动分析的臂解问题 ,论述了泵车动态分析中应解决和注意的问题 ,给出了泵车控制自动化的程序流程图和控制系统图 ,从而为提高泵车施工过程的自动化和泵车的机器人化提出了新的思路     

液压挖掘机动臂优化设计

动臂是挖掘机的关键部件,也是主要承力部件.在挖掘机施工过程中,动臂常常受到复杂的瞬态冲击载荷,造成其结构出现裂纹或变形超出范围,而动臂强度、刚度是否满足要求,将直接影响挖掘机工作安全.对动臂进行优化设计,在满足其强度的条件下,可以减轻重量,减少应力集中,使动臂几何尺寸更加合理.利用有限元软件Pro/MECHANICA中的灵敏度分析方法对动臂进行优化设计,能够实现实体建模和有限元分析的无缝集成,并且能够保证有限元分析的精度,可以提高优化设计的效率,对生产实践有着重要的指导意义.     

基于焊缝影响的井下铲运机动臂强度分析

井下铲运机动臂结构的焊结形式对其性能和强度影响巨大,针对具有不同焊接形式的动臂侧板与横梁之间的焊缝结构形式进行了有限元分析与研究,获得了各因素对焊缝强度的一般影响规律,提出了更加合理的抗疲劳性能的焊缝结构形式。给出侧板坡口角度为40°、角焊缝加强高尺寸不超过7 mm、所形成的焊缝表面为内凹形的焊接结构更能满足井下铲运机工作机构强度要求。     

Who Benefits from a Resource Boom? Evidence from the Marcellus and Utica Shale Plays

We analyze the impact of the recent energy boom in the Marcellus and Utica shale formations on local labor markets in Ohio, Pennsylvania and West Virginia. Unique to our analysis is the use of origin-destination files (LODES) from the U.S. Census Bureau which provide employment statistics at the census block level based on where jobs are located and where workers live who hold those jobs. The richness of this data enables us to identify cross border mobility of workers as labor demand increases due to greater resource extraction. We find that increases in the value of new oil and gas production significantly increases local employment and average earnings in the county, but that a large fraction of new jobs are filled by workers who reside outside of the county. Specifically, a one standard deviation increase in the value of new oil and gas production per capita in a county-year increases workplace employment by 283 jobs, decreases the fraction of jobs held locally, and increases the flow of workers from counties 25-200 miles away. Furthermore, we find some positive employment spillovers across industries, but these new jobs largely appear to go to non-local residents as well. We do find evidence that the earnings distribution shifts to the right for both local residents and workers who reside outside the county.     

基于Rayleigh-Ritz法的伸缩臂瞬态动力学分析

伸缩臂的瞬态动力学分析对伸缩臂的设计和使用具有重要的指导意义。基于Rayleigh-Ritz分析法对高空作业车的伸缩臂进行瞬态动力学分析。通过定义Rayleigh阻尼系数和模态分析获得所需的频率范围,然后计算出Rayleigh阻尼系数。分别在三个工况下完成了伸缩臂的瞬态动力学分析,获得了结构Von Mises等效应力随时间变化的曲线以及伸缩臂头部位移随时间振动情况的曲线。并探讨了不同频率范围下Rayleigh阻尼系数和阻尼比对结构振动的影响,为伸缩臂的瞬态动力学分析研究提供参考。     

轮式装载机两种动臂结构的力学性能对比分析

对装载机两种类型的工作装置——六连杆工作装置与八连杆工作装置进行简要介绍,并对其主要部件动臂进行结构力学对比分析.首先,分析在装载机典型作业过程中动臂的承载工况与作业载荷,其中重点分析偏载工况下动臂承载的特点.其次,建立两种动臂的有限元分析模型,为了提高分析的准确性,采用接触单元法来模拟动臂与销轴之间的连接作用.最后,...