发动机减振皮带轮轮毂结构NVH影响分析

某自主研发发动机开发阶段进行台架NVH测试时发现,发动机前端噪声较其它三个面噪声高3dB左右,进一步排查分析,发现减振皮带轮辐射噪声明显。通过对减振皮带轮结构进行优化,将内圈轮毂增加不同形式的去重孔结构,以减轻发动机前端辐射噪声,NVH改善明显,确定最优结构方案。

聚离子液体催化山梨醇脱水制异山梨醇的研究

采用自由基聚合法合成了氨基化聚乙烯基咪唑离子液体,通过铌改性及酸改性的方法制得强酸性聚合离子液体催化剂,通过FT-IR、GPC、XRD及TG等对催化剂理化性质进行表征。将该催化剂用于无溶剂条件下山梨醇催化脱水制异山梨醇的反应,结果表明,在Nb/[VIM]NH_(2)-3催化剂质量分数为10%、140℃、6 kPa的条件下,异山梨醇收率高达94%,相应山梨醇完全转化。该催化剂循环使用5次后,异山梨醇收率仍在90%以上。氨改性能够有效提高酸化强度,而铌酸根的存在则能够稳定H+离子,提高活性组分的分散性,从而提高了催化剂性能。

A NEW QUADRILATERAL THIN PLATE ELEMENT BASED ON THE MEMBRANE-PLATE SIMILARITY THEORY

A new effective path has been proposed to formulate thin plate element by using the similarity theory between plane elasticity and plate bending.Because of avoiding the difficulty of c(1)continuity,the construction of thin plate elements becomes easier.The similarity theory and its applications were discussed more deeply,and a new four nodes,sixteen D.O.F.(degree of freedom)thin plate element was presented on the base of the similarity theory.Numerical results for typical problems show that this new element can pass the patch test and has a very good convergence and a high precision.