带传动的弹性滑动和打滑

在<机械设计基础>教学中,很多学生对带传动的弹性滑动和打滑容易产生混淆.本文从它们产生的条件、后果的不同,以及如何有效避免传动带的打滑现象进行了深刻的剖析.     

胶带传动中弹性滑动率的计算

本文避免了分析胶带在滑动弧上复杂的变型过程，根据胶带弹性滑动的特点，利用循环连续流的原理，直接导出了便于应用的弹性滑动率的计算方法。     

带传动中包角段胶带变形对带拉力的影响

本文讨论了带传动中离心力和包角上胶带按指数规律变形对带拉力产生的影响．导出了新的F1、F2和F0计算公式,同时得出主动轮和从动轮上胶带的弹性滑动角相等的结论,并举例作了计算．验征了F-F0≠F0-F2。     

考虑孔隙损伤的黏弹性材料压力容器问题

应用线弹性微结构理论和黏弹性理论,讨论了带孔隙损伤的黏弹性材料压力容器问题.所得的解是准静态的.应力的解和线弹性的压力容器的应力解相同,位移场和损伤场与带孔隙损伤的线弹性材料压力容器问题的位移场和损伤场相似.     

弹性波在声子晶体中的带结构

本文用平面波方法,研究了Pb圆柱体在epoxy基体中按周期性排列时的弹性波带结构,研究发现弹性波在将质量密度较大的介质柱嵌入质量密度较小的基体构成的声子晶体中将有完全带隙出现.     

弹性波发生器作用下柔轮变形机理的研究

利用非线性有限元方法对谐波齿轮传动柔轮在弹性波发生器作用下变形与变形力进行了计算分析,得到:柔轮径向变形量与径向变形力的相关规律,柔轮初始变形力与柔轮形变基本成线性关系.计算结果与实验结果对比显示,两者趋势吻合.     

心理弹性与高职生心理健康

心理弹性是从弹性力学中引出的一个心理学概念,目前日益为心理学界所关注。本文从心理弹性入手,探讨了心理弹性与心理健康的关系及其对高职生心理健康的影响。     

弹性波在声子晶体中的带结构

本文用平面波方法，研究了Pb圆柱体在epoxy基体中按周期性排列时的弹性波带结构，研究发现弹性波在将质量密度较大的介质柱嵌入质量密度较小的基体构成的声子晶体中将有完全带隙出现。     

弹性函数的几何机理

弹性函数是研究当自变量有微弱变化时,函数的相对变化率。文章构造一条初始弹性直线,从几何的角度分析,弹性函数就是函数的切线斜率与初始弹性直线斜率之比;也是函数在弹性支点的微分与初始弹性直线在弹性支点的增量之比。在修订参考文献的基础上,着重对几何机理进行分析。     

职业教育与普通高中教育需求的价格弹性、收入弹性、交叉价格弹性分析

对2004-2007年间职业教育和普通高中教育的价格弹性、收入弹性和交叉价格弹性进行分析,结果表明:两类教育需求相对于教育价格表现为缺乏弹性;两类教育需求相对于居民收入表现为缺乏弹性,职业教育需求收入弹性大于普通高中教育需求收入弹性;交叉价格弹性分析表明,普通高中教育价格对职业教育需求的影响大于职业教育价格对普通高中教育需求的影响,但相互的交叉价格弹性仍表现为缺乏弹性。     

无级变速器（CVT）滑差率的试验研究

本文首先介绍了无级变速器滑差率的数学分析,讨论了无级变速器负载对滑差率的影响。在进行试验设计的基础上,进行了不同油压条件下连续加载时滑差率的试验,并利用Matlab软件进行试验数据分析。数据分析表明,无级变速器在合适油压时可以实现弹流润滑,在中低转矩时滑差率可以保持在7％-10．8％,此时可以获得较为理想的传动效率。     

Experiment and Simulations on Lubrication Performance of EMP Journal Bearing

In recent years, much attention has been devoted to the design and operation of bearings made of elastic metal plastic (EMP). The surface of the bearing bush is covered by a layer of polymer PTFE(polytetrafluoroethylene). The physical performances of the polymer are quite different from that of metal. It can reduce friction because of its lower surface energy, and it is more difficult for the fluid to be adhered. Consequently, the slip will exist at the oil-bush interface. The journal bearings made of this material are researched in this article. Through test, the existence of slip is proven and the equation of the slip velocity for the EMP journal bearing is established when shear stress up to a certain value. Thus, the classical Reynolds equation is modified. The lubrication mechanism is analyzed by some simulation results.     

弹性金属氟塑料径向滑动轴承润滑特性的实验研究及建模仿真

In recent years, much attention has been devoted to the design and operation of bearings made of elastic metal plastic (EMP).The surface of the bearing bush is covered by a layer of polymer PTFE(polytetrafluoroethylene).The physical performances of the polymer are quite different from that of metal.It can reduce friction because of its lower surface energy, and it is more difficult for the fluid to be adhered.Consequently, the slip will exist at the oil-bush interface.The journal bearings made of this material are researched in this article.Through test, the existence of slip is proven and the equation of the slip velocity for the EMP journal bearing is established when shear stress up to a certain value.Thus, the classical Reynolds equation is modified.The lubrication mechanism is analyzed by some simulation results.     

Progressive failure analysis of slope with strain-softening behaviour based on strength reduction method

Based on the strength reduction method and strain-softening model,a method for progressive failure analysis of strain-softening slopes was presented in this paper.The mutation is more pronounced in strain-softening analysis,and the mutation of displacement at slope crest was taken as critical failure criterion.An engineering example was provided to demonstrate the validity of the present method.This method was applied to a cut slope in an industry site.The results are as follows:(1) The factor of safety and the critical slip surface obtained by the present method are between those by peak and residual strength.The analysis with peak strength would lead to non-conservative results,but that with residual strength tends to be overly conservative.(2) The thickness of the shear zone considering strain-softening behaviour is narrower than that with non-softening analysis.(3) The failure of slope is the process of the initiation,propagation and connection of potential failure surface.The strength parameters are mobilized to a non-uniform degree while progressive failure occurs in the slope.(4) The factor of safety increases with the increase of residual shear strain threshold and elastic modulus.The failure mode of slope changes from shallow slip to deep slip.Poisson’s ratio and dilation angle have little effect on the results.     

中欧规范钢-混组合梁抗弯承载力计算方法对比

在收集钢-混凝土组合梁试验研究资料的基础上,分别采用中国规范GB 50917-2013、JGJ 138-2016、欧洲规范Eurocode 4(简称EC4)及线弹性法,计算所收集试件的抗弯承载力,并与试验结果进行比较。结果表明:GB 50917-2013、JGJ 138-2016与EC4中抗弯承载力的计算方法,主要的不同在于有效宽度的取值、是否考虑滑移效应的影响以及是否计入纵向钢筋对抗弯承载力的贡献GB 50017-2017与JGJ 138-2016的计算方法得到的抗弯承载力的计算理论值与试验实测值更加接近,且数据更为稳定GB 50917-2013不仅考虑了整体栓钉布置导致的滑移效应,还考虑了纵向钢筋对承载力的贡献,所计算出的结果偏于保守线弹性法比塑性理论更为保守。由于目前的计算方法与实际情况仍有一定误差,下一步建议从有效宽度、纵向钢筋对抗弯承载力的贡献与滑移效应的角度出发,提出更适用于计算钢-混凝土组合梁抗弯承载力的方法。     

常用低指数晶面标准极射图绘制及应用

在详细阐述晶面(晶向)标准极射赤面投影原理及其完整投影图绘制过程的基础上，绘制了立方晶系常用的低指数晶面(晶向)标准极射赤面投影示图；应用“滑移三角块”扼要阐释了滑移系确定与优先滑移、复滑移、双滑移及晶体在滑移过程中的转动行为。     

电磁滑差离合器在小型汽车无级变速中的应用研究

针对目前应用于小型汽车的自动变速技术现状。提出利用电磁滑差离合器实现小型汽车无级调速的理念。阐述了其技术原理和可行性,分析了电磁离合器的机械特性,提出了对电磁滑差离合器电控系统的数学建模和运用C语言及32位微控制器搭建软、硬件平台的关键技术。肯定了电磁滑差离合器对小型汽车无级调速的研究价值。     

Theoretical Calculation and Analysis of Slip and Deformation for Concrete Sandwich Panels

Slip and deformation of concrete sandwich panels under uniformly distributed loads is concerned. The effect of slip on the deformation of concrete sandwich panels are studied,and the analytical expressions of slip and deformation for concrete sandwich panels is obtained. These formulae can describe the slip distribution and account for its effect on deformation. In order to restrict the bound of formula, the formula of crack moment is obtained. The results of theoretical calculation are compared with those of tests and finite element methods. The comparison shows that the results of theoretical calculation are in accord with those of tests and finite element methods. So the theoretical calculation can be used to calculate slip and deformation of concrete sandwich panels in practical projects.     

Hybrid slip model for near-field ground motion estimation based on uncertainty of source parameters

The hybrid slip model used to generate a finite fault model for near-field ground motion estimation and seismic hazard assessment was improved to express the uncertainty of the source form of a future earthquake.In this process, source parameters were treated as normal random variables, and the Fortran code of hybrid slip model was modified by adding a random number generator so that the code could generate many finite fault models with different dimensions and slip distributions for a given magnitude.Furth...     

基于小波包滑动阈值的信号去噪

传统信号去噪方法常采用门限法对噪声信号的小波或小波包变换做阈值处理以达到去噪的目的。本文介绍了一种利用小波包滑动阈值去噪的新方法,通过对信号的小波包分解系数的滑动阈值量化,得到重构的去噪信号。计算机仿真结果表明,滑动阈值法具有很好的实用价值。