采用模拟退火算法对皮米磁头进行形状优化

采用优化设计方法优化一种皮米磁头的形状,能够降低磁头飞高,提高硬盘的存储密度及磁头的飞行稳定性。优化设计以磁头俯仰角和形状尺寸为约束,以磁头在磁盘半径方向内侧、中间、外侧稳定飞行时的飞行高度和侧倾角与优化目标值间的波动最小为优化目标建立优化模型,采用模拟退火算法对优化模型求解。优化结果表明,优化后磁头的飞浮高度可从7 nm降低到5 nm,而且磁头寻轨时磁头的稳态飞行波动得到明显改善,能够满足工程上对飞高的波动性要求。最后,比较了提高磁盘转速后初始磁头和优化磁头的稳态飞行特性,结果表明磁盘转速对优化结果有影响,改变磁盘转速建立新的优化模型可以得到适合新条件的优化磁头。     

非线性压电式能量采集器

由于非线性技术可使压电式能量采集获得较宽的振动频率和较高的输出电压,本文基于非线性振动研究了一种压电式能量采集器。基于Duffing模型测试得到了非线性压电能量采集器的振动方程,对其振动特性进行了仿真测试。在不同永磁体间距的条件下,测试了非线性压电式能量采集器的开路输出电压,结果表明,当激振台加速度为20m/s2时,该非线性压电式能量采集器的最大输出电压从线性系统输出时的131V提高到208V,最大输出功率为43.264mW,主共振频率变化范围达到18Hz。该Duffing模型的结构可以在小范围内改变非线性压电式能量采集器的共振频率,同时提高其输出电压。     

硬盘头盘界面的微观接触模型及动力学响应分析

针对硬盘头盘界面纳米级别微观接触问题,提出改进的GW接触模型计算微观接触力并引入分子间作用力建立头盘界面微观接触的力学模型,在此基础上建立头盘界面的两自由度动力学模型.利用龙格库塔方法求解不同接触状态下磁头的动态响应,结果表明:当磁头降低到一定飞行高度,头盘接触会导致磁头的自激振动,该动力学行为是造成磁头飞行失稳的关键...     

基于非线性控制的直齿圆柱齿轮箱主动振动仿真研究

针对直齿圆柱齿轮箱振动幅度较大问题,设计了非线性主动控制系统,并对动态误差进行仿真验证。创建了直齿圆柱齿轮的动力学模型,推导出刚度和角度之间的非线性变化方程式。分析了齿轮输入和输出位置变化关系式,建立了小齿轮逆运动学模型,设计了一种带前馈环的非线性控制器,通过模型反演与前馈控制对齿轮输出动态误差进行补偿。在不同频率和不同转速干扰条件下,采用Matlab对齿轮输出动态误差变化进行仿真验证,并且与线性控制方法进行比较分析。结果表明:在不同频率和转速干扰条件下,采用线性控制方法,齿轮输出的动态误差波动幅度较大;而采用非线性控制方法,齿轮输出的动态误差波动幅度较小。采用非线性控制方法,齿轮输出的动态误差波动幅度较小,从而抑制了齿轮箱的振动幅度,提高了齿轮传动精度。     

一种采用复合磁电换能器的振动能量采集器

设计了一种由悬臂梁、磁电换能器和永磁体组成的新型振动能量采集器.环境振动引起换能器与永磁体相对运动,使得作用到换能器的磁场变化,变化的磁场引起换能器得到电输出.理论分析了影响换能器与永磁体相对运动的磁场力和永磁体的非线性运动情况.实验结果表明:在振动激励频率为33 Hz,振动加速度为0.5 g的条件下,输出电压峰峰值45.1 V,输出功率112.1 μW.     

基于非定常气动特性的高架动车组振动特性试验研究

定常横风引起的非定常气动特性影响高架运行列车的安全性和舒适性。开展定常横风下高架动车组的风洞试验,测试记录其车体表面压力时程曲线,进而分析其非定常气动特性及振动特性。试验结果表明,同一侧滑角同一风速下,车体中部同一侧测点的时程压力平均值差别不大,基本相等。当侧滑角保持90°不变时,测点气动压力的平均值、最大值和最小值与合成风速的二次方成正比;随着风速的增加,测点非定常压力波动加剧,波动幅度显著增大。当合成风风速保持60 m/s不变时,测点气动压力的平均值、最大值和最小值与侧滑角的1.27次方成正比;随着侧滑角的增大,测点的峰峰值呈现抛物线变化规律,非定常波动幅度先减小后增大。高架动车组车体的主振频率带随横风风速的增大基本保持不变,随侧滑角的增大基本保持不变;振动频率均在0～18 Hz范围内,并明显存在几个主要振动频率带,分别为8～10 Hz、0～2 Hz、14～16 Hz及16～18 Hz。     

ZnO压电薄膜制备及压电仿真特性分析

压电能量收集是近年来研究的热点话题，为了优化ZnO压电薄膜结构，提高其输出电压值，采用磁控溅射法进行制备并对其晶向结构进行表征。同时，利用有限元软件ANSYS分析ZnO压电微悬臂梁结构尺寸变化对输出电压的影响并得出振动频率、加速度激励与输出电压之间的关系。结果表明，制备的ZnO纳米薄膜表面成型质量较好，具有衍射峰(002)择优取向方向生长。增大振子长度、减小宽度及选取适合的厚度能够提高输出电压。当加速度2.5 g,频率500 Hz下输出电压最大为0.589 V。     

振动对格莱圈密封性能的影响

硬岩掘进机(TBM)工作环境复杂且常伴随着强振动问题,在TBM工作过程中,推进液压缸经常出现内泄漏,主要原因是振动减弱了液压缸密封圈的密封能力。首先建立在基础振动作用下的液压缸间隙波动数学模型,利用MATLAB/Simulink仿真分析不同基础振动参数下间隙波动规律,再通过ABAQUS软件建立格莱圈的二维轴对称模型,研究间隙波动幅值、间隙波动频率对格莱圈密封性能的影响。研究结果表明:格莱圈密封能力随着基础振动幅值的增大而减弱;基础振动频率小于30 Hz,大于60Hz范围内,格莱圈密封能力随着频率的增大而减弱;基础振动频率在30-60Hz之间时,频率的变化对格莱圈密封性能影响不大。     

多场耦合多方向振动俘能器建模及响应分析

针对多方向振动俘能器对低频、低幅值激励的响应输出性能低等问题,在振动俘能结构中引入非线性磁吸力,提高俘能器的响应频带和能量转换效率。研究了非线性磁振子模型,建立了基于广义Hamilton变分原理的横、纵向振动系统机电耦合模型,对系统动力学方程进行无量纲化并数值求解。搭建了振动俘能器性能测试平台,开展了多场耦合振动俘能器频谱特性及响应输出的分析实验。结果表明,引入磁铁可显著提高系统能量转换效率,当磁铁间距15mm、激励幅值0.5m/s~2时,相比无磁力输入的情况,系统响应电压提高了6倍左右,谐振频率从18Hz降至9.5Hz左右,解决了压电俘能器频带窄、响应频率高及输出电压低等问题。     

换向激励式压电振动俘能器

为提高在低频、宽带、高强度及大振幅振动环境下的可靠性，提出一种换向激励式压电振动俘能器，它由拾振器和换能器组成。换能器的振动方向垂直于拾振器振动方向（环境振动方向），振动方向的转换通过磁力换向结构实现，换向结构使响应振幅不随外部激励的增加而一直增加，从而提高可靠性。建立了俘能器的动力学模型，通过数值仿真和实验获得了相关参数对其输出特性的影响。仿真和实验结果表明：激励频率小于20 Hz时，该两自由度系统存在两阶谐振频率使输出电压达到峰值，一阶为拾振器谐振频率，二阶为换能器谐振频率。随着拾振簧片长度和拾振质量的增加，一阶谐振频率升高，所对应的输出电压基本不变；二阶谐振频率基本不变，所对应的输出电压逐渐升高；工作频带变宽。当外部激励振幅达到阈值时，换能器的响应振幅被有效控制，输出电压不再随之增加，最佳负载电阻为540 kΩ，此时输出功率最大为0.4 mW。实际应用中可通过改变俘能器的结构参数调整谐振频率及输出电压，将响应振幅控制在安全区域内，以适应低频、宽带、高强度及大振幅的工作环境。     

Analysis on dynamic characteristics in time domain of slider with ultra thin spacing

With increasing recording density in computer hard disks,the flying height of the magnetic head becomes 10 nm or less.The numerical method of the control equations needs to be optimized consistently wi...     

Analysis of Rarefied Effects of a Nano-scale Magnetic Head/Disk

When the decrease in the space between magnetic head and disk arrived at 10 nm or less, which is much lower than the mean free path of gas molecules, the gas flow presents distinctive features against the macro features because of the rarefied effects. The modified Reynolds equation considering rarefied gas effect is used to calculate the rarefied region of a negative pressure magnetic head working in the distance of 10 nm. Inverse Knudsen number was adopted to calculating the ratio of the rarefied area. According to the numerical results, discussions and analyses are then presented to reveal the rarefied effect on the working performances of a magnetic head. The results show that the magnetic head works in the slip-flow and transition regions and moves to the transition region with the increase in velocity. Furthermore, the maximum rarefied effects occur at the side edges where the flying height is thinner and pressure is lower, rather than in the minimum flying height on the rear. The results also show that with considering the rarefied effects, the load-carrying capacity of the magnetic head and the maximum pressure decrease significantly, but the minimum pressure slightly changes.     

表面结构对纳米级气膜稀薄流域分布的影响

磁头与磁盘的特征高度目前已经下降到纳米量级,在此微小间隙下,气体表现出明显的稀薄效应特征。建立适用于纳米间隙下的控制方程,并根据方程特点采用特殊处理方法成功对控制方程进行数值求解,采用数值分析和实验方法分析表面结构变化对稀薄流域和磁头飞行姿态的影响。研究结果表明：在纳米级气膜润滑间隙下,采用逆 Knud-sen 数来划分稀薄流域比仅从特征膜厚高度方面考虑更合理;负压型磁头的主要工作区间在滑流区和过渡区,且过渡流域所占比例要明显高于滑流区域。稀薄效应最大的区域不是在气膜厚度最薄的磁头尾部,而是在压力突然下降且气膜较薄的阶梯过渡区域;磁头 U 型气垫、尾端两侧浅台阶和中间台阶结构变化会影响气流流向,从而影响压力分布,使得稀薄流域也跟随发生变化。     

硬盘磁头飞行姿态的实验研究

用动态飞行高度测试仪DFHT测试了在不同转速下磁头的飞高、俯仰角和侧翻角,磁头飞行高度和俯仰角,随着磁盘转速的增大而增大,而侧翻角则先增加后减小。由结果可以看出,随着转速的增加,俯仰角变化比较大,说明磁盘转速对磁头的左右翻转运动的影响比较大,而侧翻角变化相对比较微弱,用动态电性能测试机测试相同情况下不同转速下输出磁信号的幅值,可以看出随着飞高的增加,输出信号的幅值也随着减小。     

磁性液体微压差传感器校准信号源的研究

提出了一种新颖的低频(0.1～100Hz)磁性液体正弦压力信号源,可用于微压差传感器校准实验,该信号源能够产生与激励电流频率相同的正弦微差压.利用单自由度受迫振动原理分析了输入电信号和输出压力信号之间的函数关系.采用有限元方法(FEM)分析了磁性液体正弦压力信号源内的磁场分布并计算了磁性液体所受磁场力.最后搭建了测试信号源性能的实验平台,并给出了实验结果,由此计算了系统的固有频率及阻尼比等特征参量.实验结果显示与理论分析一致.     

安装误差对纳米间隙磁头飞行姿态的影响研究

考虑安装误差引起的磁头俯仰角误差和侧翻角误差,建立了磁头飞行数学模型,通过数值方法分析了安装误差对纳米间隙磁头飞行姿态主要参数的影响,并与试验结果进行了对比分析。结果表明,俯仰角误差对飞行高度和俯仰角有明显影响,随着俯仰角安装误差的增加,磁头飞高和俯仰角偏差增加,对侧翻角的影响可以忽略。侧翻角误差只对侧翻角有明显影响,随着侧翻角安装误差的增加,磁头飞行侧翻角偏差增加,对磁头飞行高度和俯仰角的影响可以忽略,理论分析和实验结果吻合较好。磁头设计和装配时,应控制磁头的俯仰角安装误差。     

A study of electrical charge at head-disk interface

The electrical charge at head-disk interface (HDI) of disk drives becomes increasingly important as head-disk spacing drops below 10 nm range. In this study, a new method of measuring electrical charge at HDI is presented. It involves measuring magnetic read-back signals (i.e. PW50), while the flying height (FH) is lowered by electrostatic force. Typical HDI charges are in the range of –0.2 to –0.9 V, depending on individual head–disk combination. Experiments were also conducted to eliminate the HDI charge by using an ionizer and surface treatment of magnetic heads. It was found that the HDI charge can be effectively eliminated by treating the magnetic head with a fluorinated carbon coating. The mechanisms of HDI charge generation and elimination are discussed.     

Inert Gas Filled Head–Disk Interface for Future Extremely High Density Magnetic Recording

Inert gas filled head–disk interface (HDI) is a possible solution in reducing the magnetic spacing between the magnetic head and the magnetic media for achieving further increased recording density of a magnetic recording system. This article investigated the flying and thermal performances of a thermal actuated slider at inert gas filled HDI by using a couple-field analysis method which consists of a finite element model of the entire slider, an air bearing model based on the generalized lubrication equation and a heat transfer model which incorporates various molecular dynamics models and considers temperature effects. The simulation studies showed that the variation of gap flying height (FH) with the heater power in the inert gas is quite similar to that in air. It is also found that the slider’s thermal actuation efficiency in helium is slightly better than those in argon and air. However, the temperature effects in a fully sealed drive are totally different to those in an open drive. As a result, the inert gas filled HDI normally requires a larger thermal actuation stroke due to the temperature effects in a fully sealed drive.     

硬盘磁头超薄气膜润滑研究进展

介绍硬盘磁头发展状况以及超薄气膜润滑理论的研究现状，提出超薄气膜润滑研究中存在的问题，如10nm以下一毪行间隙的润滑理论模型、超薄气膜润滑有效的数值计算方法，以及建立飞行高度试验台和开发磁头气体轴承设计分析软件模块等问题，并介绍一种新型有效的计算磁失磁盘超薄气膜的数值计算方法。     

Experimental investigation of AE and friction signals related to the durability of head/disk interface

The durability of a hard disk drive is one of the most critical issues that must be optimized for best performance. Especially as the flying height of the head slider of a hard disk drive decreases over the years, the concern for surface damage and head contamination continues to grow. In this paper the characteristics of AE and friction signals for various operating conditions using CSS and drag tests were investigated from the durability point of view. Also, the wear characteristics of the laser bumps on a magnetic disk were compared between the CSS and drag tests. The general shapes of the AE and friction signals during a single CSS test were quite similar even under less than ideal operating conditions. However, it was found that the AE signal was more sensitive than the friction signal in assessing the damage of the slider/disk interface. Finally, a correlation was established between the CSS and drag testing methods with respect to the laser bump wear. This outcome suggests that the drag test may be used to accelerate the surface damage effect of head/disk system.