土壤源换热系统的有限元分析

讨论了竖直埋管在半无限大介质中的换热模型的计算,将虚拟热源法输入到有限元软件MARC中对换热器的温度场求解,并绘制了其相应的温度分布曲线图。针对等效管,单U型管,双U形管在温度影响半径方面进行横向比较,以确定等效管理论是否真正贴近实际,单U和双U的实用性效果。     

Comparative study of flavonoid and scoparone accumulation in different Citrus species and their susceptibility to Penicillium digitatum

Fungi of the genus Penicillium are responsible for substantial post-harvest losses in Citrus fruits. The results obtained following artificial inoculation of Citrus fruits with Penicillium digitatum showed that the degree of fungal development depended on the Citrus species. Thus, the mature fruit of Citrus paradisi were more susceptible to this fungus than the mature fruit of Citrus limon, Citrus sinensis,Citrus clementina Hort. ex Tan., and Citrus unshiu (mak) Marc. The results point to an inverse correlation between the degree of susceptibility of Citrus species to this fungus and the flavanone content – hesperidin in C. sinensis, C. clementina Hort. ex Tan. and C. unshiu (mak) Marc.; naringin in C. paradisi and the flavanone hesperidin and the flavone diosmin in C. limon. Thus, in C. sinensis,C. clementina Hort. ex Tan and C. unshiu (mak) Marc. the highest levels of the polymethoxyflavones, sinensetin, tangeretin, heptamethoxyflavone and nobiletin, were observed in the least susceptible varieties and viceversa. In the case of C. paradisi, no significant differences were detected in the polymethoxyflavone levels between varieties, while in C. limon, polymethoxyflavones were hardly detectable. The production of scoparone was observed in all the species and varieties studied after inoculation with the fungus, especially in C. limon fruits. Based on the evidence, it seems that flavanones, flavones, polymethoxyflavones (phytoanticipins) and scoparone (a phytoalexin) may well be involved in the defence mechanisms of Citrus fruits against P. digitatum. Depending on the Citrus species in question, the relative participation of one group of secondary compounds or another may vary.     

基于Marc的金属塑性加工有限元模拟

介绍了金属塑性加工有限元模拟分析的目标和方法。结合实例,论述了利用有限元分析软件M SC.M arc实现塑性加工过程数值模拟分析的方法和步骤,并以模拟分析的结果指导生产实际,提高塑性加工行业的科学化水平。     

正面吊司机室FOPS受冲击时的动态响应分析

采用MSC.Patran/Marc软件,建立了正面吊司机室落物保护结构(FOPS)受冲击时的有限元分析模型,依据国际标准ISO 6055的要求,对FOPS动载试验和冲击下落试验分别进行模拟分析,得到了在冲击载荷作用下结构的应力、变形等响应参数,并对比相应技术标准进行了安全性分析,为正面吊FOPS的优化设计提供了结构冲击强度的参考数据,同时也为其它工程机械FOPS抗冲击强度设计起到参考和借鉴的作用.     

连铸坯在加热炉内的温度场数值模拟

采用MSC.Marc有限元模拟软件对加热钢坯进行埋偶试验,得出加热炉内部的实际炉气温度,并以此为边界条件。以钢坯入加热炉时的温度为初始条件,建立钢坯在加热炉内的三维温度场模型;计算钢坯在步进式加热炉内的温度场变化情况,得出不同热装温度的钢坯在加热炉内的温度变化;优化实际生产中的加热工艺。该研究为提高工厂生产效率,节约能源起到指导作用。     

多种软件协作在大坝有限元分析中的应用

针对大坝采用有限元分析单一软件建模时操作繁琐复杂、效率低等不足,基于AutoCAD、HyperMesh和MSC.Marc软件的各自特点,提出了综合应用三种软件的优势完成有限元分析过程的方法。实例结果表明,该方法可使有限元分析过程清晰明了、操作简捷流畅、参数设置方便、出错易控制和修改,大幅提高了大坝有限元分析的精度和效率。