共查询到20条相似文献，搜索用时 609 毫秒
1.
针对某往复压缩机噪声偏高问题,采用虚拟预测技术对压缩机进行了低噪声结构分析研究.首先建立了由柔性机体、柔性曲轴和刚性连杆、活塞及飞轮组成的往复压缩机的多体动力学模型.通过动力学仿真求解得到传递给机体的各种激励载荷,再根据直接积分法法求解出压缩机机体的振动响应结果,仿真得到的机体部分测点结果与实验结果吻合较好.最后根据有限元动态结果来预测其机体表面辐射噪声,计算出机体的辐射声功率与实测结果相一致. 相似文献
2.
基于结构健康监测系统的悬索桥运行模态识别(英文) 总被引：2，自引：0，他引：2
介绍了联合应用峰值法和互谱法的模态参数识别方法,并提出了一种新的主梁振型优化方法.将上述方法应用于润扬大桥悬索桥的运行模态识别系统中,利用结构健康监测系统采集的振动响应数据获取结构的模态参数.作为应用实例,对台风麦莎作用下的主梁、主缆和桥塔振动响应数据进行了模态参数识别.结果表明:主梁部分振型的模态频率不仅能从主梁的振动响应识别出来,而且能够从主缆和桥塔振动响应中识别,主粱、主缆和桥塔之间存在较强的耦合振动.此外,将运行模态的识别结果和成桥之初的现场测试结果进行了对比,二者识别结果整体上吻合较好,但运行模态系统识别的部分振型模态频率,如L1和L2,发生了较明显的下降. 相似文献
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研究了新风换气机的动态特性,以改善新风设备工作时的振动噪声,对XHBX-D2TH型号的新风换气机进行了试验模态研究,得到了新风机结构的8阶模态固有频率、阻尼比和模态振型等参数,为进行有限元模态仿真分析,振动、噪声分析与结构优化创造了条件. 相似文献
5.
徐燕铭 《天津职业院校联合学报》2014,(12):84-88
在计算曲轴频率和振型过程中,针对曲轴模态分析时一直采用的是自由模态,考虑由旋转产生离心力对曲轴频率和振型的影响,计算出多种转速情况下的频率和振型,并进行比对,充分说明曲轴在实际工作过程中产生的振动情况,结果更加符合实际情况。 相似文献
6.
《东南大学学报》2019,(4)
为了提高滚动轴承性能退化评估中退化指标的早期故障敏感性和稳定性,提出了一种基于嵌入选择的邻域保持嵌入(ESNPE)方法.首先,采用变分模态分解(VMD)对获得的振动信号进行分解,提取各本征模态分量的奇异值和相对能量等组成高维故障特征集.然后,采用NPE流行学习方法提取特征空间内的嵌入特征.针对传统NPE存在有效嵌入信息容易被抑制的问题,构建了一种基于Spearman相关系数的嵌入选择策略.该策略通过相关系数的大小衡量嵌入特征的有效性,并通过一阶差分的方法在轴承退化的早期阶段确定并保留有效嵌入特征.最后,采用支持向量数据描述(SVDD)模型构建性能退化指标,实现轴承性能退化评估.使用轴承全寿命退化实验数据,并与传统的主成分分析(PCA)方法和NPE方法特征提取分析结果进行对比,验证了所提方法在提升退化指标早期故障敏感性和稳定性方面具有优越性. 相似文献
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刘成武郭小斌 《福建工程学院学报》2020,(6):518-523
为了研究结构几何参数及铺层参数改变对碳纤维复合板的振动声辐射特性影响,利用有限元/边界元法计算了碳纤维复合材料板的振动声辐射特性参数,并以降低结构振动噪声为目标对其进行了优化分析。研究表明:加筋、增加筋数和增加铺设层数能降低结构的辐射噪声。3 种铺层角度中,[0°/90°/45°]辐射噪声最低。在第一阶波峰处,优化后声功率值相比优化前减少了大约4 dB。研究结果可为降低结构辐射噪声提供理论依据。 相似文献
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为处理非比例阻尼系统可能出现的过阻尼模态,提出了一种改进的复模态叠加强迫振动分析方法,建议无论模态是否过阻尼,复模态振动分析时应成对使用复模态．以一个连接任意布置外部阻尼器的悬臂梁典型非比例阻尼系统为例,其第1阶模态会随阻尼系数的增加而过阻尼．在厘清复模态响应与实际动力响应关系的基础上阐述了采用改进复模态叠加法获得时域响应、传递函数和方差的完整理论方法．将方程分为实部和虚部,使得原复数域运动方程成为基于实数矩阵的增广状态空间方程,从而克服了采用复数矩阵计算时变响应的困难．此外,针对基于白噪声滤波的外部激励,提出了一种高效方差响应评估方法,降低了计算资源消耗．结果表明,相较于假设模态法,复模态叠加法的结果更接近于有限元结果．基于遍历法研究最优阻尼器参数和位置时,采用多个小阻尼阻尼器优于单个大阻尼阻尼器． 相似文献
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汽车发动机曲轴轴颈与轴承之间的径向间隙很小，这一间隙可使曲轴自由转动而不发生松旷和产生径向跳动。如果轴颈与轴承之间的径向间隙发生变化，往往会造成曲轴轴颈与轴承的早期磨损和破坏，使发动机工作振动增大，噪声升高，油耗增加，事故增多。曲轴轴颈与轴承发生损坏的形式有刮伤、磨损、疲劳剥落、腐蚀、烧熔等。曲轴轴颈与轴承损坏的原因磨损汽车发动机在工作过程中，曲轴轴颈与轴承之间产生高速摩擦，尤其在发动机低速运转或起动时，由于润滑油膜难以建立而产生干摩擦，致使轴承产生磨损。疲劳剥落曲轴不断承受周期性的气体作用力、… 相似文献
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在模态分析的理论基础上,对模态分析在车身声振设计中的应用进行了探讨。通过实例分析了模态分析在车身声振设计中应用的基本方法、基本步骤,这为汽车振动和噪声的特性研究提供了有价值的参考依据。 相似文献
11.
ZHANG Zhi ming ZHU Li jin YU Jun 《上海大学学报(英文版)》1999,3(3):227-233
Ｎｏｍａｎｃｌａｔｕｒｅ ｂｉｊ,Ｂｉｊ（ｉ,ｊ＝ｘ,ｙ） ｂｅａｒｉｎｇｄａｍｐｉｎｇａｎｄｎｏｎｄｉｍｅｎｓｉｏｎａｌｄａｍｐｉｎｇｃｏｅｆｆｉｃｉｅｎｔｓ,Ｂｉｊ＝ｂｉｊΨ３ｍｉｎ／（２ｌμ） ｃｍｉｎｍｉｎｉｍｕｍｒａｄｉａｌｃｌｅａｒａｎｃｅｏｆｂｅａｒｉｎｇｄｄｉａｍｅｔｅｒｏｆｂｅａｒｉｎｇｅｕ,Ｅｕｅｃｃｅｎｔｒｉｃｉｔｙａｎｄｒｅｌａｔｉｖｅｅｃｃｅｎｔｒｉｃｉｔｙｏｆｍａｓｓｃｅｎｔｅｒｏｆｒｏｔｏｒ,ｒｅｓｐｅｃｔｉｖｅｌｙ,Ｅｕ＝ｅｕ／ｃｍｉｎＦｓｔａｔｉｃｌｏａｄｏｎｂ… 相似文献
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A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing. 相似文献
13.
To improve the static and dynamic performance of hydrodynamic journal bearings, a novel bearing is developed, which is a cone-shaped hydrodynamic bearing with spiral oil wedges. The major structural feature of this bearing is the three spiral circular recesses on the bearing's surface, leading to improved characteristics. This paper aims to develop a model for design and calculation of the geometric parameters and the oil film thickness, and to provide a theoretical analysis to the static characteristics using a finite element method. Some new features are introduced. 相似文献
14.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｓｉｎｃｅ 1990 ,ａｎｉｍｐｏｒｔａｎｔｄｉｓｃｏｖｅｒｙｉｎｒｏｔｏｒ ｈｙｄｒｏ ｄｙｎａｍｉｃｂｅａｒｉｎｇｓｙｓｔｅｍｄｙｎａｍｉｃｓｉｓｔｈｅｃｏｕｐｌｅｄａｃ ｔｉｏｎｏｆｔｈｒｕｓｔｂｅａｒｉｎｇｕｐｏｎｔｈｅｌａｔｅｒａｌｖｉｂｒａｔｉｏｎｉｎａｒｏｔｏｒｓｙｓｔｅｍ .Ｉｎｔｈｅ ｐｉｏｎｅｅｒｉｎｇｒｅｓｅａｒｃｈｏｆＭｉｔｔｗｏｌｌｅｎｅｔａｌ .( 1990 ) [1] ,ａｓｅｒｉｅｓｏｆｒｏｔｏｒ ｄｙｎａｍ ｉｃｃｏｅｆｆｉｃｉｅｎｔｓｏｆｔｈｒｕｓｔｍａｇｎｅ… 相似文献
15.
Based on the modal analysis theory and by using the dynamics finite element analysis model of a three-dimensional assembly circuit module, dynamic characteristics of circuit module have been studied, including both natural characteristics analysis and dynamic responses analysis. Using a subspace method, modal analysis is first carried out. The first 6 orders of natural frequencies and vibration modes are obtained. Influence of the number of the Z-shaped metal slices on dynamic characteristics of the entire structure is also studied.Harmonic response analysis is then conducted. The steady-state response when the circuit module is subjected to harmonic excitation is determined. A curve of the response values against frequencies is obtained. As a result, the optimal number of Z-shaped metal slices can be determined, and it can be assured that the three-dimensional assembly circuit module has good performance in terms of the dynamic characteristics. 相似文献
16.
ZHANG Gang YU Lie XIE You-bai School of Electromechanical Engineering Automation Shanghai University Shanghai China Xian Jiaotong University Xian China 《上海大学学报(英文版)》2000,(Z1)
1 IntroductionThe great majority of docUments about magneticbearings dealt only with the characteristics when thejournal was concentric with the radial magnetic bearing inthe past, and few research involved the ones when thejournal was eccotic with the radial magnetic bearing.For example, the bulk of documents suPPosed thecomponents Fx and F. of magnetic force depended onlyon the cUrred in x and y direchons respeGtively, bac theair gap thickness and the curvatUre of suiface shape werenot co… 相似文献
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This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of
static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal
are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of
journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic
bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the
dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered
in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled
electromechanical dynamics analysis of rotor system equipped with magnetic bearings. 相似文献
18.
A new control strategy based on modal energy criterion is proposed to demonstrate the effectiveness of the control system in reducing structural earthquake responses. The modal control algorithm combining LQR （linear quadratic regulator） control algorithm is adopted in the discrete time-history analysis. The various modal energy forms are derived by definition of the generalized absolute displacement vector. A preliminary numerical study of the effectiveness of this control strategy is carried out on a 20-storey framed steel structural model. The controlled performance of the model is studied from the perspectives of both response and modal energy. Results show that the modal energy-based control strategy is very effective in reducing structural responses as well as in consuming a large amount of modal energy, while augmentation of additional generalized control force corresponding to the modes that contain little modal energy is unnecessary, as it does little help to improve the controlled structural performance. 相似文献
19.
Rotor systems supported by angular contact ball bearings are complicated due to nonlinear Hertzian contact force. In this paper, nonlinear bearing forces of ball bearing under five-dimensional loads are given, and 5-DOF dynamic equations of a rigid rotor ball bearing system are established. Continuation-shooting algorithm for periodic solutions of the nonlinear non-autonomous dynamic system and Floquet multipliers of the system are used. Furthermore, the bifurcation and stability of the periodic motion of the system in different parametric domains are also studied. Results show that the bifurcation and stability of period-1 motion vary with structural parameters and operating parameters of the rigid rotor ball bearing system. Avoidance of unbalanced force and bending moment, appropriate initial contact angle, axial load and damping factor help enhance the unstable rotating speed of period-1 motion. 相似文献
20.
铅芯橡胶支座屈服比对大开间密肋复合墙结构隔震效果的影响 总被引：1，自引：0，他引：1
将大开间密肋复合墙结构与基础隔震技术相结合,可以有效地减小大开间密肋复合墙结构的地震响应。运用有限元分析软件SAP2000,对隔震大开间密肋复合墙结构模型进行动力分析,研究在地震作用下铅芯橡胶支座屈服比的变化对隔震大开间密肋复合墙结构隔震效果的影响。研究表明,对输入的各种地震波及其幅值,铅芯橡胶支座不仅可以取得明显的减震效果,而且可以找到一个最佳屈服比使大开间密肋复合墙结构的最大层间剪力最小,同时获得最大的控制效果。 相似文献