共查询到20条相似文献,搜索用时 31 毫秒
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针对精铣削过程中柔性工件的颤振抑制问题,提出了一种利用空气黏性的新型被动质量阻尼器。首先,该质量阻尼器由一个可在薄壁壳体内自由移动的圆柱形重物组成,通过重物和壳体之间的适当间隙提供了密集的能量耗散;其次,给出了该阻尼器的理论模型,并提出了一种合理的宽带调谐策略,使该阻尼器能够在较宽的工作范围内通过固定调谐来提供足够的阻尼效率。通过冲击实验和铣削实验对该阻尼器进行了有效性验证。结果表明:该阻尼器的临界轴向切削深度显著增加约100倍;与同等质量颗粒阻尼器相比,该阻尼器的阻尼效率明显提升,过度切削量减少了14倍;与传统调谐质量阻尼器相比,该阻尼器的峰值效率更小,但工作范围更大,因此适用于细长柔性工件的铣削加工。 相似文献
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电流变液在结构振动抑制中的应用研究 总被引:2,自引:1,他引:1
根据结构抑振的应用要求,研制出了几种零场粘度低、有场粘度变化梯度大的电流变液,并设计制作了电流变液静态屈服应力测试仪,测试出了所研制的电流变液的静态屈服性能随电场强度和液体组份比变化的曲线。利用自制的电流变液,对含电流变液的夹层板振动进行了单模态抑制,由此得出电流变液对振动机理在于:一方面通过电流变阻尼效应降低结构振动响应的幅值,特别是共振峰的幅值;另一方面通过电流变刚度效应使结构的有效刚度增加,结构的共振点发生移动,从而使结构在共振频率激励下的振幅大大降低。对本文的夹层板模型,在3kV/m m 的电场强度下,第三阶模态的响应幅值降低了90% 。 相似文献
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基于内置力执行器的铣削颤振的主动控制 总被引:3,自引:0,他引:3
高速加工中铣削颤振不仅降低工件的表面加工质量,严重时还会造成刀具或者其他加工部件的损坏,因此对电主轴铣削颤振进行控制具有重要的意义。为对电主轴铣削过程中的颤振进行有效控制,在双绕组无轴承感应电动机的基础上,提出一种具有内置力执行器的感应型高速电主轴结构,建立电主轴—刀具系统的有限元模型、动态铣削模型、双绕组感应型电主轴电磁力模型,在对具有内置力执行器的感应型高速电主轴电磁力进行解耦后,提出基于内置力执行器的电主轴铣削颤振的主动控制方案,通过仿真分析控制器的主要参数对电主轴铣削稳定性的影响。结果表明采用具有内置力执行器的感应型高速电主轴能够有效地提高电主轴铣削的稳定区域以及在抑制铣削颤振方面具有明显效果。 相似文献
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含智能流变材料铝合金夹层板结构的动力学特性研究 总被引:1,自引:1,他引:1
通过对一种含电流变液铝合金夹层板智能结构的动力学实验与仿真,分析和研究该结构在外电场作用下的动力特性变化。实验发现,利用外部控制条件(电场强度)的变化,可以改变结构的固有特性,如自然频率、结构阻尼等,可实现对结构的主动控制。数值分析时采用粘弹性材料等效处理方法模拟电流变材料,计算得到的结构振动特性与实验结果吻合较好。实验与仿真计算结果均表明,随着电场强度的增大,结构固有频率也随之出现上升,且增幅与场强有关;同时,电流变材料对结构振动所产生的阻尼效应不仅受外加电场影响,还与外加激励频率有关,响应控制实验结果说明电流变材料对结构在固有频率附近所产生响应的控制效果要更为明显一些。 相似文献
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随超精密装备加工精度和生产率的不断提高,直线气浮系统得到广泛重视和研究。为解决直线气浮系统抗干扰能力较差等问题,针对已开发的超精密直线气浮工作台,设计了电流变剪切模式阻尼器;建立了气浮工作台整体模型并基于屈服前后平滑过渡的Eyring连续本构模型通过辨识得出电流变剪切阻尼器类稳态模型;分别对零电场线性及高电场非线性电流变阻尼2种情况下的气浮工作台应用误差积分LQR控制器;为达到综合最优,进一步提出开关及滑模控制器,实验证实这2种控制策略均能同时提高系统的响应速度、减少建立时间,降低跟踪误差及纹波。 相似文献
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研制了一种多层滑动极板电流变阻尼器 ,并进行了阻尼器的动态特性实验。基于 Bingham塑性理论 ,提出了一种考虑电流变阻尼器的粘性阻尼和库仑阻尼效应的力学模型 ,该模型具有结构简单 ,模型参数少的特点。利用阻尼器动态实验数据 ,用参数优化方法对阻尼器力学模型进行了参数识别 ,仿真结果表明这种力学模型可以较精确地模拟该阻尼器的动态特性 相似文献
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电流变流体是一种新型的智能材料,在工程中有广泛的应用前景。本文利用自行设计的测试装置通过对测杆振幅、共振频率等参数的测定,研究电场作用下电流变流体刚度及阻尼变化。根据实验研究提出变参数的粘弹阻尼力学模型,描述电流变流体在电场作用下附加阻尼和附加刚度。 相似文献
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Yu Liu Zhen-yu Wang Kuo Liu Yi-min Zhang 《The International Journal of Advanced Manufacturing Technology》2017,89(9-12):2627-2636
The chatter stability in milling severely affects productivity and quality of machining. Tool wear causes both the cutting coefficient and the process damping coefficient, but also other parameters to change with cutting time. This variation greatly reduces the accuracy of chatter prediction using conventional methods. To solve this problem, we consider the cutting coefficients of the milling system to be both random and time-varying variables and we use the gamma process to predict cutting coefficients for different cutting times. In this paper, a time-varying reliability analysis is introduced to predict chatter stability and chatter reliability in milling. The relationship between stability and reliability is investigated for given depths and spindle speeds in the milling process. We also study the time-varying chatter stability and time-varying chatter reliability methods theoretically and with experiments. The results of this study show that the proposed method can be used to predict chatter with high accuracy for different cutting times. 相似文献
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Yasuhiro Kakinuma Tojiro Aoyama Hidenobu Anzai Hiroharu Sakurai Kazuyuki Isobe Katsutoshi Tanaka 《Precision Engineering》2006,30(3):280-287
An electro-rheological fluid (ERF) is a functional fluid whose viscoelastic properties vary according to the intensity of the applied electric field. ERFs are mixtures of nonconductive silicone oil and inorganic/organic composite electro-rheological particles. The properties of ERFs have been exploited to control the performance of machine elements. ERFs have been applied to machine elements such as variable dampers and clutches. However, ERFs have disadvantages, namely the sedimentation of ER particles and the requirement of a seal mechanism. The sedimentation of ER particles reduces the ER effects and results in low stability of ER devices. In order to suppress the sedimentation, and thereby improve the performance of ERF devices, a new functional material called the gel-structured ERF (ERG) is developed, whose basic properties are analyzed in this study. The ER particles are suspended in the gel component, and thus will not precipitate out. This suppresses the decrease in the ER effect caused by precipitation. The ERG developed shows a large shear stress variation in response to the applied electric field. This high performance of ERG originates in a mechanism different from the ER effects of ERF. In order to elucidate the mechanism in ERG, the behavior of ER particles was observed under an electric field. The results show that the contact conditions at the interface between electrode and ERG change rapidly in response to the applied electric field, which result in a variation in shear force. On the basis of the results of a preliminary analysis, ERG was applied to the precision clamp system of an aerostatic slider, and its performance was assessed experimentally. 相似文献
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Useful expressions are developed for the damping coefficient of two types of viscous dampers that contain electrorheological (ER) fluids. The damping action in the first type occurs in flow between stationary parallel plates; the second type has annular flow between two stationary concentric cylinders. For ER fluid control, an electric field is applied across the gap in which the fluid flow occurs. The solution for the concentric cylinder damper is based on a thin gap approximation. These solutions may facilitate solving mechanical systems problems, using ER fluids, and demonstrate the controllability of ER dampers. 相似文献