变质量柔绳问题研究

研究了一种变质量柔绳上升和下降的运动规律.     

THE FRICTIONLESS SLIDING OF AN OBJECT ALONG A ROPE

提出了物体在无摩擦情况下沿一段柔性绳索下滑运动力学问题的分析方法,利用牛顿第二定律建立耦合运动方程组,采用龙格-库塔（Runge-Kutta）方法编写程序对已建方程组进行求解,用Matlab 中的曲线拟合命令对方程组的数值解进行公式拟合,用得到的物体运动公式结合耦合运动方程组可求出物体下滑各时段绳索的内力. 提出的分析方法对物体在不同初始状态下的计算结果表明：绳索内力随物体的简谐振动呈周期性变化;物体下滑高度越高,经过相同位置时速度、加速度和绳索内力就越大.     

末端悬挂重物转动绳子的研究

给出悬挂重物的绳子在稳定转动状态下的线元方程,通过数值计算,得出绳子能弯曲稳定转动的角速度特征值.并讨论了这个特定值和悬挂重物质量的关系,还将实验图形和理论图形做了对比.     

钢丝绳捻制成形的空间几何模型与有限元分析

根据钢丝绳捻制成形原理，在考虑钢丝绳空间几何形状的基础上，建立了引入自扭转系数时钢丝绳的几何结构计算模型和钢丝绳捻制成形有限元计算边界条件模型。进而编制了相应的有限元建模程序，生成可被ANSYS直接调用的数据文件。分析了钢丝绳一次捻制和二次捻制的加工应力应变变化情况，并讨论了自扭转系数对加工应力应变的影响。     

Superelastic shape memory alloy cables: Part I – Isothermal tension experiments

Cables (or wire ropes) made from NiTi shape memory alloy (SMA) wires are relatively new and unexplored structural elements that combine many of the advantages of conventional cables with the adaptive properties of SMAs (shape memory and superelasticity) and have a broad range of potential applications. In this two part series, an extensive set of uniaxial tension experiments was performed on two Nitinol cable constructions, a 7 × 7 right regular lay and a 1 × 27 alternating lay, to characterize their superelastic behavior in room temperature air. Details of the evolution of strain and temperature fields were captured by simultaneous stereo digital image correlation and infrared imaging, respectively. Here in Part I, the nearly isothermal, superelastic responses of the two cable designs are presented and compared. Overall, the 7 × 7 construction has a mechanical response similar to that of straight wires with propagating transformation fronts and distinct stress plateaus during stress-induced transformations. The 1 × 27 construction, however, exhibits a more compliant and stable mechanical response, trading a decreased force for additional elongation, and does not exhibit transformation fronts due to the deeper helix angles of the layers. In Part II that follows, selected subcomponents are dissected from the two cable’s hierarchical constructions to experimentally break down the cable’s responses.     

钢丝绳在线非接触测长系统研究

钢丝绳成品长度是供货合同的重要指标,与经济效益、企业信誉息息相关。针对在线钢丝绳纹理变化特点,提出一种基于线结构光的非接触测长系统,通过比较钢丝绳在不同时刻,不同位置的线结构光投射条纹图像的相似性,间接测量绳长。对投射条纹提取、条纹相似性度量等关键算法进行了阐述。实验证明,系统解决了传统接触测长固有的打滑、磨损等问题,避免了钢绳在线速度变化、捻距误差等因素的影响,具有准确、高效、实时性强的特点。     

端部切向载荷作用下的压杆失稳分析及其应用

细直杆件在压应力作用下会产生横向屈曲即失稳．直杆撞击刚性平面或拉断卸载后将形成压缩波，因承载压缩载荷的长度增加可以引起失稳．冲击速度转换的压应力沿着杆件切线方向，该处弯矩和剪力为零；而众多文献设定的失稳段固支边界条件并不准确．基于精确的杆件变形曲率方程得到端部载荷指向杆件中固定点时的受压失稳条件，得到其极限状态即载荷沿杆端切向作用时失稳长度相当于两端简支的1.5 倍．对于钢丝绳拉断形成的冲击失稳，载荷恒定而长度增加，可以产生高阶屈曲即在侧向出现多次曲折，并基于尼龙-橡胶带的模拟试验给出了定性说明．     

安全绳坠落试验及分析

对多种不同型号的安全绳、缓冲包及假人系统开展实验室坠落试验分析．研究发现,相邻二次冲击的冲量之比,及相邻二次冲击的自由抛体运动持续时间之比都近似为一个定值,利用该统计规律导出估算阻尼系数的近似方法,并利用首次冲击波形的试验结果得到了三次幂非线性刚度系数,相关结果可作为安全绳性能评估的重要依据．     

Catastrophe of coronal magnetic flux ropes in fully open magnetic field

The catastrophe of coronal magnetic flux ropes is closely related to solar explosive phenomena, such as prominence eruptions, coronal mass ejections, and two-ribbon solar flares. Using a 2-dimensional, 3-component ideal MHD model in Cartesian coordinates, numerical simulations are carried out to investigate the equilibrium property of a coronal magnetic flux rope which is embedded in a fully open background magnetic field. The flux rope emerges from the photosphere and enters the corona with its axial and annular magnetic fluxes controlled by a single "emergence parameter". For a flux rope that has entered the corona, we may change its axial and annular fluxes artificially and let the whole system reach a new equilibrium through numerical simulations. The results obtained show that when the emergence parameter, the axial flux, or the annular flux is smaller than a certain critical value, the flux rope is in equilibrium and adheres to the photosphere. On the other hand, if the critical value is exceeded, the flux rope loses equilibrium and erupts freely upward, namely, a catastrophe takes place. In contrast with the partly-opened background field, the catastrophic amplitude is infinite for the case of fully-opened background field.     

Quantitative Identification of Internal and External Wire Rope Damage Based on VMD-AWT Noise Reduction and PSO-SVM

As a common load-bearing component, mining wire rope produces different types of damage during a long period of operation, especially in the case of damage inside the wire rope, which cannot be identified by the naked eye, and it is difficult to accurately detect such damage using the present technology. In this study we designed a non-destructive testing device based on leakage magnetism, which can effectively detect the internal defects of wire rope damage, and carried out simulation analysis to lay a theoretical foundation for the subsequent experiments. To address the noise reduction problem in the design process, a variational mode decomposition–adaptive wavelet thresholding noise reduction method is proposed, which can improve the signal-to-noise ratio and also calculate the wavelet energy entropy in the reconstructed signal to construct multi-dimensional feature vectors. For the quantitative identification of system damage, a particle swarm optimization–support vector machine algorithm is proposed. Moreover, based on the signal following the noise reduction step, seven different feature vectors, namely, the waveform area, peak value, peak-valley value, wavelet energy entropy classification, and identification of internal and external damage defects, have been determined. The results show that the device can be used to effectively identify internal damage defects. In addition, the comparative analysis showed that the algorithm can reduce the system noise and effectively identify internal and external damage defects with a certain superiority.