关于V带传动当量摩擦系数计算公式的修正

对现行机械设计中关于V带传动当量摩擦系数的2种计算公式进行分析.认为其中一种公式是合理的,但存在一定的误差;而另一种公式却是错误的.通过推导V带欧拉公式,给出了计算V带传动当量摩擦系数的准确公式,并在公式中引入了一个新的参数——摩擦力方向角.在考虑皮带拉力变化既有径向滑动又有周向滑动的前提下,改进后的计算公式比现有公式更加完善.     

关于V带传动当量摩擦系数计算公式的修正

对现行机械设计中关于V带传动当量摩擦系数的2种计算公式进行分析．认为其中一种公式是合理的，但存在一定的误差；而另一种公式却是错误的．通过推导V带欧拉公式，给出了计算V带传动当量摩擦系数的准确公式，并在公式中引入了一个新的参数——摩擦力方向角．在考虑皮带拉力变化既有径向滑动又有周向滑动的前提下，改进后的计算公式比现有公式更加完善．     

带传动的弹性滑动分析

通过带传动中带与带轮接触面间滑动速度公式的推导，讨论弹性滑动现象、动角及静角概念，并定量地分析了影响弹性滑动（滑动率）的因素．     

三种损失因素下V带传动机械效率计算方法研究

为了揭示V带传动的功率损失本质以便获得V带传动更为真实的机械效率计算公式,从而提高V带传动以及其后机械传动设计数据的精确性,对V带传动中弹性相对滑动的功率损失、拉弯功率损失与拉直功率损失进行了研究,结果表明,拉弯功率损失与拉直功率损失是弹性相对滑动功率损失的三倍之多,前两项损失在当前的文献中几乎没有考虑,导致给出的机械效率推荐值偏高,试验结果验证了本计算方法的精确性.     

带传动中弹性滑动的理论分析

通过对带传动的运动及受力分析，推导出带传动中带中拉力及带与带轮之间摩擦力和正压力的变化规律，推导出弹性滑动角α’及弹性滑动率ε的计算公式。     

V带传动中轴向压力的研究

介绍了摩托车上常用的V型皮带式无级变速器的工作原理.通过对V型皮带式无级变速器主动轮和从动轮的力学分析,建立了皮带传动的力学关系,推导了这种传动的设计公式,并指出了现有公式的不足,在公式中引入了一个新的参数———摩擦力方向角,给出了计算V带传动当量摩擦系数的准确公式.     

普通V带的疲劳寿命试验研究

本文论述了普通V带传动的发展概况以及设计方法。对两种典型的普通V带传动设计方法进行了分析研究,认为按滑动曲线设计法中以绕转数考虑带的寿命过于粗略;国际标准化组织推荐的方法(ISO370),虽然在计算中引入了由疲劳寿命试验决定的许用应力,但试验方法和试验条件不详,无法得到不同材质结构带的许用应力。在处理寿命和打滑的关系方面,认为按不打滑和预期使用寿命设计带传动方法(简称分立设计法)更合理。然而这种     

窄V带传动特点分析

分析窄V带的结构以及传动特点.与普通V带相比较,窄V带更符合带的工作状况,优点更显著.     

基于Matlab的低矮式破碎机V带传动模糊优化设计

针对新型低矮式破碎机中V带传动的设计实例,在满足安装条件和传动性能要求条件下．以V带根数最少为优化目标,建立了模糊优化设计的数学模型,并给出了基于Matlab的优化方法和结果分析．结果表明,在满足工作要求条件下,可使V带根数最少．     

按工作寿命优先或最大转矩优先设计V带传动

本文介绍一种优先保证V带工作寿命或传递最大转矩来设计V带传动的方法。这种方法以滑动曲线和寿命曲线为基础,初拉力和其它一些参数具有可选择性。论文阐述了提出这种方法的理由和优点,介绍了所使用的试验台和试验结果。     

表面裂纹蠕变分析的蠕变线弹簧模型

利用弹塑性断裂力学的工程估算法及等时应力应变的概念，在弹塑性线弹簧模型的基础上提出了一个三维裂纹蠕变断裂力学分析的蠕变线弹簧模型方法，并建立了有关基本方程，计算了国产２Ｃｒ－１Ｍｏ钢表面裂纹板的高温（５６５℃）蠕变断裂力学参量，从而为进一步研究三维表面裂纹蠕变扩展及寿命预报提供了基础。     

Creep properties and a creep equation of delay outburst coal and its adjacent mudstone

The study of the creep properties of coal and its adjacent mudstone is very important for understanding the mechanism of delay outburst coal. The samples of delay outburst coal and its adjacent mudstone collected from Yongshanqiao mine were used to carry out triaxial creep tests. The influence of confining pressure and axial compression on the creep test was analyzed. An accelerated creep model was constructed in parallel with a nonlinear viscous component and plastic component. It is connected with the traditional Burges creep model in series. A creep model which can describe the nonlinear viscoelastic-plastic creep model of rock was established and the corresponding creep equation was derived.According to the results of the creep test, the related parameters of the equation were fitted. The results show that, under the same confining pressure, instantaneous creep strain, creep strain of deceleration phase and constant rate creep of the coal and its adjacent mudstone are increased with an increase in the deviatoric stress. But at the same axial pressure, all of the above decrease with an increase of confining pressure. The duration time of the deceleration creep phase increases with the increase in the deviatoric stress. The theoretical values of the creep equation are in good agreement with the experimental results. It indicates that the creep properties of the delayed outburst coal and its adjacent mudstone can be well described by the creep model established in this paper.     

同步齿形带传动应用研究的几个问题

基于普通同步齿形带传动的失效形式及带齿齿廓分析 ,结合生产实际 ,提出同步齿形带传动应用中应注意的几个重要问题及解决方案。同时针对高速斜齿同步齿形带传动中存在的问题 ,进行分析研究 ,最后给出实例     

Creep behaviour and constitutive model of coal filled with gas

Coal exhibits different creep behaviours when filled with different amounts of gas. Creep tests of coal filled with 0 and 0.5 MPa gas were performed, and strain under different axial stress was compared.The three creep constitutive models which were analysed using the method fitting experimental data for determining which creep model can reflect the creep process of the test best. The results show that the deformation of coal filled with 0.5 MPa gas is more higher than that of coal filled with 0 MPa gas under the same axial stress. Gas plays a positive effect on the deformation of coal process and will accelerate creep process. And gas will reduce coal intensity and change coal creep properties.Compared with Nishihara Model and Extensional Nishihara Model, Burgers Model can reflect the three stages of creep process of coal filled with gas better. The research results can contribute to reveal coal and gas outburst mechanism.     

高温高压阀体蠕变的有限元分析

对三十万发电机组旁路装置中高压蒸汽转换阀阀体进行了有限元分析，给出了十万小时后的蠕变位移，应变及应力。     

带传动中传动带弹性性质的非线性与分析

根据现有的设计资料设计带传动时，在某些情况下不能充分发挥带传动的工作能力。本文 从带传动的基本公式分析入手，通过普通V带传动的静态和动实验及分析，得出传动带工作时其拉伸变形不符合虎克定律，应力与应变呈非线性关系，且在传递载荷较大时，仍有较大的工作潜力，从而为充分发挥带动的工作能力提供了设计依据。     

施工过程与砼徐变对建筑结构变形和内力的影响

本文介绍了文献［１］提出的混凝土杆件结构徐变分析的有限元方法，然后用有限元法对某框架结构进行了考虑施工过程和徐变影响的全过程受力分析。分析结果表明，施工过程和徐变因素对结构的变形和受力都具有显著的影响。     

带传动动力学分析及惯性力影响的研究

带传动运转过程中带与带轮之间力的作用比较复杂,传统带传动运动和力的分析没有或只部分考虑惯性力的影响,全面考虑带的惯性力的影响可提高带传动运动和力分析模型的准确性.以带的线弹性和稳态运转为前提,将与带轮接触的带微元化处理,列出周向和径向的动力学平衡方程,并加以简化,得到带传动各动力和尺寸参数之间的微分方程;通过找出相关的物理方程、力与变形的本构关系和几何边界条件,建立动力学方程解的方法.对某平带传动进行理论计算,比较考虑惯性力和不考虑惯性力结果,发现传统方程高估带传动最大力矩,而低估了动角的数值.该研究可为带传动的分析提供理论基础和为带传动的设计提供参考.     

密度与沥青低温性能关系研究

通过沥青材料的密度-温度关系以及集料的膨胀系数、温度与沥青蠕变性质、密度与沥青蠕变性质之间的关系,研究了密度和沥青蠕变性质与沥青材料的低温抗收缩裂缝性能之间的关系。结果表明,沥青材料的密度、蠕变劲度的对数、m值与温度呈线性关系,沥青材料的蠕变劲度的对数和m值与密度呈直线关系,沥青材料的密度与沥青的低温抗收缩裂缝性能密切相关,可以用密度与温度的关系判断沥青低温性能的优劣,判断结果与从蠕变性质判断的结果一致。     

Rock creep modeling based on discontinuous deformation analysis

Creep is one of the major problems of deep underground mining that must be studied theoretically, experimentally, and numerically over a long period. Experiments and field tests are methods which can directly and more accurately describe the engineering practices as compared with others. However, these approaches are also time-consuming because creep problem of rock engineering, such as the roadway/tunnel squeezing phenomenon, usually lasts from several months to a few years. A numerical method can be employed to overcome this time-consuming problem. The discontinuous deformation analysis (DDA) method was originated in 1984 and received considerable attention from geo-engineers and researchers. The current paper discusses the creep calculation methods using the continuous and the discontinuous methods, and proposes a creep analysis method based on DDA. The method proposed in this paper can directly change the stiffness matrix while inheriting the advantages of the original DDA. Applying this method does not require any changes in the contact part of DDA. Thus, this method does not have any effect on the open–close iteration and convergence and can solve the creep problem, while maintaining the advantages of the original DDA. We theorized that creep problems are static problems, and based on this, the work using DDA in this study was divided into two parts: (1) addition of a new loop for the original DDA to “discredited” the total creep time into several time elements, thereby changing the material properties in each time element; and (2) division of each of the time elements by the time steps, similar to the original DDA. In this manner, one creep problem can be solved via assembling of static problems. Afterwards, the method mentioned above is employed to modeling a tunnel case. The evolution of the displacement filed and stress field during creep are analyzed and discussed.