航空发电机传动轴扭转振动测试实验研究

航空发电机是飞机任务系统电能的主要来源,也是任务系统甚至载机正常工作的保证。考虑到任务系统工作时具有脉冲电流的特性,利用地面实验设备,模拟发电机的实际运行状态和载荷情况,进行发电机的动态测试实验,得到了脉冲电流作用下发电机弹性传动轴冲击扭转振动曲线。通过对实验结果的对比分析,证实了任务系统工作时的脉冲电流是发电机传动机构扭转振动的主要激励源,同时也是弹性传动轴出现断轴故障的主要原因;适当增大弹性轴的轴径,可以改善系统的固有特性,从而有效缓解弹性轴扭转力矩的振动峰值。     

盘式分布拉杆转子系统扭转振动非线性动力学特性分析

随着燃气轮机技术的发展,盘式分布拉杆转子系统在燃气轮机等动力机械中得到广泛应用。主要研究盘式分布拉杆转子扭转振动的非线性动力学特性,通过考虑叶盘接触效应和拉杆等效简化,建立一个新的系统扭转振动方程。利用多尺度方法求解动力学方程解析解,并获得拉杆转子系统扭转振动幅频方程和解析曲线,根据奇异性理论获得系统转迁集,并利用动力学系统的扰动方程零解稳定性研究原系统的周期解的稳定特性,并发现系统动力学参数对其影响规律,并根据新模型建立实际结构参数与非线性动力学参数的联系,给出系统稳定性边界条件。分析结果对燃气轮机转子系统动力学设计具有一定的指导意义。     

发电机碳刷多点全周摩擦引起的不稳定振动分析

以发电机碳刷与转轴之间发生的摩擦振动为对象,研究这类特殊周向多点全周摩擦振动机理。根据碳刷工作原理,建立多点全周摩擦力计算模型,采用热弹性力学方法建立摩擦截面温度场和转子热弯曲计算模型,将热弯曲模型与转子振动有限元模型耦合求解振动响应。以某发电机为例进行分析,仿真分析和试验研究了碳刷轴全周摩擦振动特征。研究表明,发电机碳刷与转轴之间的多点全周摩擦会引发振动周期性波动和爬升,不稳定现象与不平衡力、碳刷-转轴不同心度和碳刷摩擦因数有关,可以通过精细动平衡、适当增大碳刷-转轴不同心度和减小碳刷摩擦因数来消除。     

柔性天线面对星载天线的扰动研究

针对柔性天线面对星载天线的扰动问题,应用固定界面模态综合法和Lagrange方程,截取柔性天线面低阶模态,缩减星载天线系统的自由度,并通过轴末端与天线面交界面的协调关系,推导了大范围运动的星载天线刚柔耦合动力学模型,克服了忽略天线面弹性变形对刚体大范围运动的影响,所建立的耦合动力学模型计算效率高并具有足够的精度。考虑天线面为刚体和柔体情况,分别对星载天线系统进行仿真并进行对比分析,结果表明,初始时刻柔性天线面对卫星本体姿态和天线指向影响很小,随着关节力矩持续作用,激起柔性天线面震荡,加剧自身的弹性振动,进而引起星载天线的抖动,造成卫星位姿和天线指向偏差变大,严重影响了星载天线的指向精度。结论对星载天线指向精度的分析与控制具有重要的理论价值及工程实际意义。     

侧铣加工动力学建模及仿真

本文以两自由度的铣削加工为研究对象,建立了闭环的动态力～振动切削动力学仿真模型;应用模型仿真切削力与振动并与实测数据进行比较;证实该模型仿真切削力与振动的准确性。该结果对预测铣削力与振动,选择合适的切削参数具有实际意义。     

基于刚柔-机电耦合的机床直线电机进给系统动态性能仿真研究

以某新型直线电机驱动的车铣复合机床Z轴进给模块为研究对象,在多刚体动力学仿真模型的基础上,考虑导板柔性和结合面参数,构建了Z轴模块刚柔耦合模型,采用快速正弦扫描实验对仿真模型进行了实验验证。进一步,将直线电机伺服控制系统考虑进来,提出了一种综合考虑刚柔—机电耦合作用的数控机床进给系统动态性能研究方法,并对其进行仿真分析。仿真结果表明,机床机械结构和伺服控制系统共同对机床进给系统的动态性能产生了重要的影响。     

考虑臂架弹性的动臂起重机动力学建模及振动分析

动臂起重机负载的振荡会大大降低起重机工作时的防倾翻能力。首先建立动臂起重机的静态模型以便全面了解动臂起重机的系统结构。然后运用AUTOLEV建立了考虑臂架弹性的动臂起重机的一个简单模型及完全多体动力学模型,仿真出动臂起重机各机构运行时弹性臂架输出角度及臂架顶部负载对阶跃输入的响应曲线。从仿真结果可以看出,动臂起重机中车体的运行及臂架的回转和起升都会导致负载的剧烈振荡从而影响整机工作的安全性。详细而全面的负载振动分析为系统的振动控制提供了有力的依据。     

大型风电齿轮箱系统耦合动态特性的研究

综合考虑轮齿啮合时变刚度、齿轮传递误差、齿轮啮合冲击以及风载变化等因素影响,建立具有多级齿轮传动的大型风电齿轮箱的齿轮-传动轴-轴承-箱体系统耦合非线性动力学模型。对风电齿轮箱系统有限元模型进行耦合模态分析,运用模态叠加法对齿轮箱系统在内部激励与外部激励综合作用下的振动响应进行求解。将仿真结果与实验数据对比,进而得到齿轮箱各点振动位移、速度、加速度及结构噪声等系统动态评价指标,为大型风电齿轮箱动态特性的准确评价及齿轮系统动态性能优化设计提供理论依据。     

基于三次迟滞模型的超声电机圆环定子主共振响应

摘 要 将改进的三次多项式迟滞模型用于描述压电材料的弹性迟滞非线性特性,建立了压电材料二维非线性本构关系。根据Hamilton原理和Rayleigh-Ritz假设模态方法,建立了不考虑界面力时旋转行波超声电机圆环定子驻波振动的非线性动力学模型。用多尺度法求解定子的一次近似主共振响应,通过定常解分析,发现定子主共振响应中存在振幅跳跃和多解现象,着重分析了压电材料弹性迟滞非线性参数对主共振响应的影响。结果表明,迟滞参数a使幅频响应曲线左偏并出现多解现象,迟滞参数a和b同时影响系统响应振幅的大小。数值计算验证了解析解的正确性。从理论上揭示了压电材料弹性迟滞非线性对圆环定子主共振响应的影响,为超声电机的优化设计和控制提供了理论依据。     

具有约束层阻尼旋转复合材料轴的动态特性研究

复合材料驱动轴在高速旋转下的振动抑制,是先进直升机和汽车传动系统结构设计需要考虑的重要问题。约束层阻尼技术是工程领域内普遍采用的实用有效的阻尼减振设计方法;然而通过采用约束层阻尼处置方式增加复合材料传动轴的阻尼能力的研究报道,目前国内外很少见到。从应力-应变关系、应变-位移关系出发,推导出复合材料Timoshenko轴、约束层与黏弹性层的动能及势能的数学表达式,采用Hamilton原理建立具有约束层阻尼的旋转复合材料轴的运动学方程。采用广义Galerkin法对动力学方程进行了离散化,建立了广义坐标表示的自由振动方程组,通过特征值求解得到系统的固有频率和阻尼比;基于比例阻尼假设和四阶Runge-Kutta数值积分方法求解上述方程,得到系统的自由振动响应曲线。通过数值分析揭示了约束层材料、黏弹性层材料、铺层方式、长径比和转速对具有约束层阻尼的旋转复合材料轴的固有振动特性以及自由振动响应特性的影响。     

100kA快响应精密冲击分流器研制及特性分析

冲击电流为暂态电流波形,持续时间短且波形不可重复,测量误差影响因素众多难以评估.研制快响应精密冲击分流器,采用同轴管式结构,分析分流器的测量原理及尺寸设计.研究分流器的瞬态响应过程,将输出信号焊接至电阻体外侧,消除趋肤效应的影响.分流器的稳态电阻测量值为0.969 7 mΩ,杂散电感为32 nH,测量额定电流时,电阻温...     

压电式动态力传感器校准方法的研究

针对智能制造行业里压电式传感器的动态性能校准问题,介绍了针对传感器动态力参数的相关方法和脉冲力法校准装置,在装置上完成了试验验证和分析。介绍了两种常规的动态力校准方法,针对不同的校准方法建立了运动方程,做出了差异性分析。然后介绍了一种基于绝对法测量的压电式传感器脉冲力法校准装置,装置的结构包括基于刚体碰撞的脉冲力发生装置和基于外差式迈克尔逊干涉仪的测量系统,说明了工作原理和解算方法。最后利用建立的校准装置对典型压电式传感器进行动态力校准,进行结果分析和可靠性验证。     

脉冲力校准装置锤体质量块设计及数据验证

脉冲力发生装置的锤体质量块是脉冲力发生装置的重要组成部分,锤体质量块的结构固有频率是保证动态力校准精度的重要条件,通过对锤体质量块的设计及改进进行了描述和验证,最后通过数据验证说明设计是合理的,满足对动态力传感器的校准需求。     

脉冲力校准装置提升及扶正机构设计及数据验证

脉冲力发生装置的提升和扶正机构是脉冲力发生装置的重要组成部分,提升和扶正机构对动态力校准的准确性和重复性起到至关重要的作用。对提升装置的选型和扶正机构的改进进行了描述和验证,实验数据证明了设计的合理性,满足对动态力传感器的校准需求。     

Dynamic electromagnetic torque model and parameter estimation for a deep-bar induction machine

A dynamic analytical electromagnetic torque model for a deep-bar induction machine is presented. The model is based on the space-vector theory of electrical machines. The parameters are estimated using the data provided by the numerical impulse response test performed within the two-dimensional time-stepping finite element analysis. Two different impulse tests are studied. The impulse excitation is applied to the stator voltage and rotor position angle, and the parameter estimates are compared. The applicability of the impulse test is based on the assumption of linear behaviour in the neighbourhood of an operation point. Hence, one of the main objectives is to study the validity of the impulse test. From the results of the angle impulse test, a frequency range of negative damping is detected. The phenomenon is also studied by measurements.     

Reduction of residual vibration in a rotating flexible beam

Summary. The reduction of residual vibrations of the position control of a rotating flexible beam is investigated. The control scheme is achieved by combining Input Shaping Technique (IST) with a piezoceramic actuator ( PZT ) attached to the surface of the beam. IST reduces residual vibration in the beam by convolving the desired torque with a sequence of impulses. A majority of the current IST is inherently open-loop where impulse application at an inaccurate instance can lead to system performance degradation. Thus, in order to improve the control performance of a flexible manipulator, the residual vibration generated due to those or the uncertainty model was further suppressed by the PZT. The optimal control voltage was determined by the Linear Quadratic Regulator (LQR) technique. The dynamic simulation shows that the proposed method has not only nice robustness properties for suppressing the vibration due to an inaccurate model or the instance of impulse application, but also the voltage applied on the PZT decreases 50% or more than only using PZT, in other words, the extra energy consumption is reduced significantly by the proposed method.     

Self-Integrating Rogowski Coil for High-Impulse Current Measurement

This paper presents the operating principle, the performance under impulse condition, and the design of a self-integrating Rogowski coil for measuring high-impulse currents. Oscillatory and overdamped unidirectional impulse currents are generated up to 10 kA and measured by different methods, namely, two commercial impulse current transformers, a resistive shunt, and the newly designed self-integrating Rogowski coil. For the resistive method, the voltage drop across the shunt affects the total voltage measured across the test object and causes distortion in the case of simultaneous measurement by an impulse current transformer having a small aperture. The Rogowski coil theory under impulse current conditions is presented. The concept of transmission lines is used, and the line parameters are optimized to achieve a self-integrating mode and avoid spurious effects of reflections and stray capacitances. The output voltage linearity of the designed self-integrating Rogowski coil is checked using different linear and nonlinear loads and coil termination resistances. It is found that at a termination resistance of 1 $Omega$, satisfactory impulse current waveforms are measured by taking the commercial impulse current transformer as a reference signal. Results reveal that the measurement errors for the current peak and front and tail times are $pm$2%, $leq$6%, and $leq$ 12%, respectively. Overdamped impulse currents are generated by different generator capacitances, where comparisons between the measured and calculated current waveform parameters have shown good agreement.      

Modeling and Simulation of a salient-pole synchronous Generator with dynamic eccentricity using modified winding function theory

This paper models and simulates a salient-pole synchronous generator using a modified winding function theory and more precise stator and rotor winding distribution with dynamic eccentricity between the stator and rotor. Air-gap permeance is also computed more accurately compared to currently available methods. Inductances with this method are compared to those obtained from other methods and it is shown that the results are closer to those obtained from finite element computations. Finally, the calculated inductances are used in a coupled electromagnetic model for simulation and studying the frequency spectrum of the stator line current in the presence of dynamic eccentricity.     

Transient modeling of multiparallel tubular linear induction motors

In this paper, we model single and multiparallel generator driven tubular linear induction motors by the current filament method, in transient and dynamic states. Using a previously written code for transient and dynamic modeling of a single motor, we simulate a sample motor noted in a reference paper and compare the results with those obtained by using our current filament method. This comparison confirms the accuracy of our method. Finally, we model a system of two or more parallel motors and show that it is feasible to achieve greater muzzle velocities by paralleling certain designs of motors.     

磁爆加载初始阶段薄壁金属管的冲击变形研究

通过磁爆加载初始阶段脉冲磁动力对薄壁金属管加载过程的分析,将加载过程离散为强流发生、磁场形成和冲击加载三个进程,进而建立了薄壁金属管受磁载荷冲击变形的理论模型,并在此基础上,利用MAXWELL和AU-TODYN软件联合仿真的方法研究了薄壁金属管的冲击变形特征,最后对结果进行了试验验证。研究表明:理论分析、数值仿真和试验结果吻合较好,薄壁金属管在脉冲磁动力加载下的变形趋势与其外侧包裹炸药爆炸加载的情况相似,磁动力分布及其第一峰值的时间进程直接影响薄壁金属管的最终变形。