膜片联轴器扭转特性实验研究

为了研究螺栓法兰连接、波动载荷和不同预紧力矩对膜片联轴器扭转刚度的影响,搭建了联轴器扭转刚度测试实验台。通过扭转实验机施加扭矩,并采用角位移编码器测量了主动、从动法兰盘的相对扭角;采用扭力扳手实现螺栓预紧力矩的调节。实验结果表明:随着负载的增大,法兰螺栓连接出现了严重的松弛;负载波动情况下,载荷变化越大,刚度变化越大;预紧力矩的减小使滑移力矩减小,但第3阶段的刚度变化不大。预紧力矩减小至6N·m时,第1阶段和第4阶段的刚度明显减小。     

金属-橡胶球铰扭转刚度试验研究

针对金属-橡胶球铰扭转刚度试验,分析了2种金属-橡胶球铰的结构与工作原理,设计了球铰水平纯扭转、垂直压缩扭转、组合扭转、系统扭转和组对扭转5种试验方案,并进行了分析对比;研究了不同径向预载荷、扭转速度和扭转方式对球铰扭转刚度的影响。结果表明,试验设计与实际工况一致;水平纯扭转和垂直压缩扭转2种试验方式均适用刚度试验;当增加径向预载荷或增大扭转速度时,球铰扭转刚度变大,单边加载扭转刚度大于正反加载扭转刚度。     

用微机控制电子万能试验机测试橡胶减振器的静态刚度

介绍了用微机控制电子万能试验机测试橡胶减振器静态压缩刚度和静态扭转(摆动)刚度的试验程序和方法,采用专用试验程序软件和工装夹具进行试验,使得扭转力矩(M)和扭转角α的测试和计算过程更为简便.使用微机控制的试验程序自动得出试验结果,大大提高了检测效率.     

橡胶-钢球支座刚度的有限元分析

通过非线性有限元方法对橡胶-钢球支座在轴向拉伸、扭转和弯曲的大变形载荷作用下的力学行为进行分析,得出支座的轴向刚度、扭转刚度和弯曲刚度与变形的关系。轴向刚度和弯曲刚度随着变形的增大而减小,扭转刚度随着变形的增大而增大,但总的来说,变化很小。     

焊筋法兰的设计与计算

焊筋法兰体积小、重量轻,并适于现场就地施工,故已日益普遍应用。本文扼要的介绍了焊筋法兰的几种结构尺寸设计和强度与刚度的简易计算方法。     

压力容器法兰螺栓疲劳强度浅析

介绍了一种压力容器法兰螺栓疲劳强度的计算方法,通过引入法兰当量受力面积,计算螺栓、法兰和垫片系统的相对刚度Kr,最后根据应力幅法计算螺栓疲劳强度。     

玻璃钢叶片剪切与扭转分析

本文应用薄壁结构理论分析空腹和矩形主梁结构的玻璃钢叶片剖面弯曲和扭转产生的剪应力以及剪切中心、扭转刚度。算例分析表明在叶剖面内加腹板,可降低前后缘剪应力,也可调节剪切中心与形心的相对位置,以改善叶片的气弹性能。     

机械密封的扭转变形计算方法与影响因素

针对机械密封环的典型结构,基于圆环理论,建立了密封环结构受力与变形的分析模型。采用圆环理论解析式和有限元法对密封环扭转变形进行了对比计算,分析了密封环的几何结构形状、几何结构尺寸和辅助密封圈的安放位置等因素对密封环扭转变形的影响规律。结果表明:采用理论解析法替代有限元法的计算方法是可行、有效的;复杂截面密封环的台阶长或宽各小于4 mm时,均可直接忽略台阶对扭转变形的影响;辅助密封圈的安放位置和密封环结构形状对扭转变形量均具有重要影响;密封环尺寸在变化不大的前提下,其对扭转变形影响不大。研究结果完善了高压机械密封的设计理论与方法。     

对GB 150《压力容器》有关内容的商榷——法兰刚度校核要求和其他

GB 150《压力容器》参考ASMEⅧ-1列入了整体法兰(包括带颈和不带颈)的刚度校核方法,但并未列入活套法兰(包括带颈和不带颈)以及反向法兰的刚度校核方法。在其标准释义中表示,之所以不列入的原因是根据Waters法设计的法兰,在控制各项应力后,具有较大锥颈的法兰其刚度会自动得到满足。此外,带颈活套法兰可以看作为整体法兰,因此,对活套法兰不校核刚度并不影响法兰密封性。文章对此提出了一些看法。     

低温罐主要部件应力计算及泄漏分析

介绍了低温罐设备在内压和重力载荷作用下,长圆形法兰及耳座的强度和刚度的详细计算方法,分析了常规设计计算的不足之处,结合实际工程经验,提出计算需采用有限元方法进行局部应力分析和泄漏分析。在经过对计算对象进行建模、网格划分、荷载施加、计算、后处理、应力评定、泄漏评定等实施步骤后,得到该低温罐的长圆形法兰强度、刚度均满足要求,安全可靠,耳座设计满足强度要求的结论,探讨了管法兰的应力计算方法由粗略转向精细的现实意义。     

轮胎静态及侧偏刚度有限元分析

考虑子午线轮胎的材料非线性、接触非线性以及大变形等复杂的力学特性,采用Abaqus软件建立轮胎三维有限元分析模型,研究充气压力和负荷对轮胎静态刚度(径向刚度、侧向刚度、纵向刚度、扭转刚度)和稳态侧偏刚度的影响,并给出了相应的负荷与变形之间的关系。结果表明,充气压力对轮胎的静态刚度有显著影响;负荷对径向刚度、扭转刚度和侧偏刚度影响显著。     

Finite element analysis of torsional free vibration of adhesively bonded single-lap joints

Adhesively bonding is a high-speed fastening technique which is suitable for joining advanced lightweight sheet materials that are dissimilar, coated and hard to weld. In this paper, the free torsional vibration characteristics of adhesively bonded single-lap joints are investigated in detail using finite element method. The effectiveness of finite element analysis technique used in the study is validated by experimental tests. The focus of the analysis is to reveal the influence on the torsional natural frequencies and mode shapes of these joints caused by variations in the material properties of adhesives. It is shown that the torsional natural frequencies and the torsional natural frequency ratios of the adhesively bonded single-lap joints increases significantly as the Young′s modulus of the adhesives increase, but only slight changes are encountered for variations of Poisson's ratio. The mode shapes analysis show that the adhesive stiffness has a significant effect on the torsional mode shapes. When the adhesive is relatively soft, the torsional mode shapes at the lap joint are slightly distorted. But when the adhesive is relatively very stiff, the torsional mode shapes at the lap joint are fairly smooth and there is a relatively higher local stiffening effect. The consequence of this is that higher stresses will be developed in the stiffer adhesive than in the softer adhesive.     

PR1型聚乙烯缠绕结构壁管的环刚度计算方法研究

聚乙烯缠绕结构壁管的环刚度是其抵抗径向变形的重要性能参数,影响着其外压承载能力。以PR1型截面的埋地聚乙烯缠绕结构壁管为例,对管道轴向截面进行截面单元划分,同时,综合考虑截面发生变形、局部材料迁移等情况,建立截面单元的简化计算模型,并对截面单元关键尺寸参数进行修正。在此基础上,研究PR1型聚乙烯缠绕结构壁管环刚度的计算方法;通过实例验证了PR1型聚乙烯缠绕结构壁管的截面单元的形心、惯性矩以及环刚度计算方法的准确性,相关研究方法与结果将对聚乙烯缠绕结构壁管的设计、生产与使用以及其他复杂截面管道的环刚度计算提供一定的参考作用。     

Torsional instability of carbon nanotubes encapsulating C60 fullerenes

The torsional instability of a single-walled carbon nanotube containing C60 fullerenes is investigated using molecular dynamics. A newly revealed observation of a reduction of the shear stiffness of the carbon nanotube filled with C60 fullerenes during torsion shows an unusual local buckling nature of the material instead of a global buckling of an unfilled carbon nanotube at a critical torsional angle. Such local buckling largely increases the critical torsional angle for the instability of the material, and hence enhances its stability. Simulations show that the local buckling of the material is a result of the van der Waals interaction between the nanotube and the encapsulated C60 fullerenes.     

Torsional elastic instability of double-walled carbon nanotubes

In this paper, a theoretical analysis of the torsional buckling instability of double-walled carbon nanotubes (DWCNTs) and the DWCNTs embedded in an elastic medium is presented based on the continuum elastic shell model and Winkler spring model. Using the proposed theoretical approach, the influences of the aspect ratio, the buckling modes and the surrounding medium on the torsional stability are examined in detail. The simulation results show that the torsional instability of DWCNTs can occur in different buckling modes according to the aspect ratio. The van der Waals (vdW) interaction force between nanotubes reinforces the stiffness of nanoshells. Thus, the DWCNTs possess higher buckling stability than the SWCNTs without considering vdW interaction force.     

Drying of Prone to Twist Boards in a Pre-Twisted Position

A method to minimize twist has been investigated; i.e., drying the boards in a pre-twisted position. It has been found that Norway spruce boards can be deformed toward straightness by this method. The force exerted by a board on its holders during drying in a pre-twisted position has been measured. When the variation in torsional stiffness as a function of temperature and moisture content is accounted for, it is found that a creep deformation of the board occurs both during the drying phase and the cooling phase. In addition to mechano-sorptive creep, a deformation released by a change in temperature also seems to occur.     

轮胎与整车匹配技术研究

对轮胎与整车匹配技术进行研究。结果表明:改变轮胎的侧偏刚度可以改变整车的不足转向度;增大轮胎扭转刚度可以增大舵感,增大轮胎的侧偏刚度可以解决轮胎响应慢问题,调整轮胎回正力矩可以改善轮胎的转向线性感;减小轮胎的抓着力可以改善其在极限工况下侧倾抑制不足;改变轮胎花纹块结构、材料和轮胎接地面积等可以改善抓着力;减小轮胎的纵向和垂向刚度可以减小冲击入力感,减小轮胎的包容刚度可以减小包覆感,增大轮胎的垂向阻尼可以快速衰减振动。     

12R22.5 18PR无内胎全钢载重子午线轮胎压力分布测试及磨耗改进

通过对12R22.5 18PR无内胎全钢载重子午线轮胎进行外缘尺寸、五项刚性(径向刚性、横向刚性、纵向刚性、扭转刚性和包络刚性)、接地印痕和接地压力进行测试以及对接地压力分布进行有限元分析,对轮胎结构进行优化以提高耐磨性能.结果表明,与原设计轮胎相比,优化轮胎的接地印痕形状更接近矩形,接地印痕长轴略有缩短、接地印痕面积增大7.75％,压力分布不均匀度减小;装车路试优化轮胎的耐磨性能提高20％.     

免充气塑料轮胎支撑结构对性能的影响

免充气塑料轮胎的支撑结构对轮胎性能有直接影响。本研究提出了一种具有连续支撑结构的免充气轮胎,利用ABAQUS软件,与两种现有免充气轮胎进行应力大小、接地性能以及刚度性能的对比。结果表明:连续支撑结构可改善免充气轮胎的应力,接地压力的分布均匀性;同时,连续支撑结构轮胎的纵向刚度、横向刚度均远好于同规格现有免充气轮胎和子午线轮胎;扭转刚度性能接近同规格子午线轮胎。通过分析可知,连续支撑结构轮胎在复杂工况路面有显著的优势,具有良好的发展前景。