同步器环簧刚度优化与截面尺寸分析

提出了一种改善环簧刚度特性的结构方案,确定了环簧的周向定位结构,通过研究环簧截面尺寸对其刚度的影响,优化了环簧的结构设计。

基于负刚度碟簧装置的竖向隔震支座力学性能研究

在竖向隔震中,为同时满足高静态刚度和低动态刚度的需求,提出一种基于预压碟簧的负刚度装置(disc spring negative stiffness device,DSNSD),利用其与已有的预压弹簧装置(prepressed spring device,PSD)集成为拥有高静低动刚度的竖向隔震支座(PSD-DSNSD隔震支座)。首先对DSNSD的构造与工作原理进行详述,建立相应的力学模型,再通过Python进行数值模拟,考察上述碟簧装置的力学性能,最后利用Abaqus建立PSD-DSNSD竖向隔震支座的有限元模型进行模拟。结果表明:加入DSNSD后竖向隔震支座的隔震刚度显著降低,验证了将DSNSD用于竖向隔震增效的可行性。说明DSNSD在启动后可提供负刚度,从而有效减小整体装置的竖向刚度。

二系空簧横向刚度对高速列车动力学性能的影响

基于动力学软件SIMPACK仿真分析了我国某高速列车二系空簧横向刚度对车辆动力学性能影响,并对二系空簧横向刚度进行了优化分析。仿真结果表明:车辆临界速度随二系空簧横向刚度增加有所增加;车辆横向稳定性、乘坐舒适性随二系空簧横向刚度增加有所恶化,垂向平稳性受其影响不大;轮轴横向力、脱轨系数、磨耗指数随二系空簧横向刚度增加变化不大,轮轨垂向力、轮重减载率随二系空簧横向刚度增加略有下降。该高速列车二系空簧横向刚度可以在0.1~0.2 MN/mm范围内进行选取,此时,车辆动力学性能在最优范围内。

底盘无簧悬架刚度与悬架摩擦

根据工程实践,提出了通常在计算汽车底盘悬架系统的悬架垂直刚度时被简化的,但却很重要的无簧悬架刚度的概念,介绍了一种无簧悬架刚度的简易测量方法。由测量得到的无簧悬架刚度曲线的迟滞现象,引申出悬架摩擦的概念,分析产生悬架摩擦的原因,及其对行驶平顺性的影响。

轨道车辆空气弹簧疲劳分析

利用基于开裂能理论的疲劳分析方法对空气弹簧进行寿命评估.借助有限元技术对带有附加气室的空气弹簧系统进行仿真,提取空气弹簧胶囊每个单元中心的应变历程,将应变历程代入开裂能计算公式计算每个单元中心所有可能开裂平面的开裂能峰值,再利用开裂能峰值计算撕裂能峰值,进而计算对应的等效撕裂能,最后利用等效撕裂能计算每个单元中心所有可能开裂平面的裂纹扩展速率和对应的疲劳寿命.将疲劳预测寿命与实验寿命进行比较,结果表明疲劳预测寿命是实验寿命的1.91倍,验证了疲劳仿真模型和方法的可靠性.

150柴油机喷油器弹簧使用状况分析及改进探讨

根据150系列柴油机喷油器弹簧随喷油泵考核的试验结果，从弹簧刚度和弹簧工作时的预压缩量入手，分析研究了造成喷油器喷油压力下降的原因，提出了影响喷油器喷油压力的零件之改进方向。

导向钻井工具关节轴承组合系统及其内部应力分析

针对深井高温重载工况下导向钻井系统中关节轴承易发生磨损和疲劳剥落的问题,介绍了一种关节轴承组合系统,并用有限元法对该系统进行了静力学分析和冲击性能分析,结果表明,合理匹配关节轴承系统内部碟簧的刚度,可以较好地分配井底的钻压。

一种不平衡衔铁电磁继电器抗振性优化设计方法

一直以来,不平衡衔铁继电器的抗振性是设计人员头疼的难题。本文从吸、反力配合曲线入手,通过分析曲线中与继电器耐环境力学相关点,提出一种量化设计电磁继电器耐环境力学性能的方法。

Equivalent Stiffness of Metal Clip⁃Like Piezoelectric Spring Structure

Piezoelectric ceramic is hard to be integrated with the normal spring structure.To address the above problem,this paper proposed a new geometry of a clip‑like spring which is very similar to binder clip in our daily life.The equivalent stiffness of the designed piezoelectric clip‑like spring is thoroughly researched and discussed through the theoretical model,the finite element simulation and the experimental measurement.The results confirm the possibility of designing a compact piezoelectric clip‑like spring,and the equivalent stiffness can be tuned through the several key geometric parameters.Finally,theoretical predictions confirmed by experimental results show that the equivalent stiffness of the spring structure is as function of the instantaneous angle of the clip,this stiffness variation caused by the geometric nonlinearity can be ignored in some practical engineering applications,which means it is possible to linearize the clip‑like spring and simplify the following dynamic model of the corresponding piezoelectric oscillators.

Static-deformation based fault diagnosis for damping spring of large vibrating screen

Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.

Higher mode effects in hinged wall with BRBsin base-frame structures using distributed parameter models

To investigate the effect of higher modes on the displacement and inner forces in HWBB(hinged wall with buckling-restrained braces in base)-frame structure,distributed parameter models for both the HWBB-hinged frame structure and the HWBB-MRF(moment resisting frame)structure are built.The hinged wall is simplified as a flexural beam.BRBs(bucking-restrained braces)are simplified to a rotational spring.MRF is simplified to a shear beam.Vibration equations of distributed parameter models are derived.Natural periods,natural modes of vibration,inner forces and displacements of the distributed parameter models are derived based on the vibration equations using numerical methods.The effect of the relative stiffness ratio and the rotational stiffness ratio on the higher mode effects is investigated.For elastic structures,the global displacement and shear in MRF are predominantly controlled by the first mode,while the shear and bending moment in the wall are significantly affected by higher mode effects.The effect of the yielding of BRB on the inner forces distribution in the HWBB-hinged frame is investigated.The results indicate that the first mode will no longer contribute to the inner forces and the contribution from higher modes to inner forces increases after the BRBs yield.Displacement is not sensitive to higher mode effects and it is controlled by the first mode after the BRBs yield.Parameter analysis demonstrates that the displacement amplitudes are reduced with the increase in the flexural stiffness of the wall before the flexural stiffness reaches a certain value.The first three periods decrease with the increase in the rotational stiffness.With the increase in the rotational stiffness ratio,the contribution from the first mode decreases while contributions from both the second mode and third mode increase.

Simulation and Experimental Research for Piping Damper with Plunger-type Accumulator

It can be beneficial to reduce vibrations in shipboard piping, so the authors designed a new kind of piping damper with a plunger-type accumulator.Special requirements for the piping damper included low impact displacement, low speed, as well as an appropriate locking speed.Inside the damper, a plunger-type accumulator was installed and on the outside of the piston rod, a tube with exposed corrugations was added.Between the piston and the cylinder, a clearance seal was added.Using mathematical modeling, the effects of the dynamic performance of the damper's impact displacement on vibrations were observed.Changes to the clearance between the piston and the cylinder, the stiffness of the spring in the accumulator, the throttle valve size, and locking speed resistance of the damper were respectively simulated and studied.Based on the results of the simulation, dampers with optimal parameters were developed and tested with different accumulator spring stiffnesses and different throttles.The simulation and experimental results showed that parameters such as seal clearance between piston and cylinder, accumulator spring stiffness and throttle parameters have significant effects on the damper's impact displacement, low speed resistance and locking speed.

Compromises in Vehicle Suspension Design

When designing vehicle suspension systems, compromises are usually made when setting the range of values for spring stiffness and damping constant. Suspension parameters are set depending on the operational requirements of the market. Passenger car for example, would require high quality damping while off road vehicle requires high spring stiffness setting. A quarter vehicle suspension model has been used to study the suspension transmissibility in handling and ride at various frequency ratios. The results obtained show that as the frequency ratio increases, transmissibility for handling reduces with increasing suspension stiffness and increases as the damping constant is increased. On the other hand, transmissibility for ride deteriorate as the spring constant is increased but approaches the ideal as the damping constant is increased. The dynamic magnification of the sprung masses reduces while that of the unsprung masses improves as the frequency ratio is increased.

Analysis on resonant shake table with novel variable stiffness mechanism

To improve the efficiency and amplify the exciting force of a shake table,a novel variable stiffness mechanism(VSM)constructed by four leaf spring-lever combinations(LSLCs)was designed.Three VSMs were installed in parallel on the traditional hydraulic shake table to constitute a resonant shake table(RST).The static model of the VSM and the dynamic model of the RST were constructed by considering the large deflection of leaf springs and the geometrical nonlinearity of L-shaped levers.The variable stiffness property of LSLCs was analyzed and verified through static experiments.The simulation and vibration experiments on the dynamic properties of the RST prototype were conducted.The results show that compared with traditional shake tables,the RST consumes lower exciting force in a specified frequency bandwidth when outputting the same displacement of vibration.Under a harmonic vibrational excitation,the RST is effective for vibration enhancement using broadband frequency resonance and can save energy to some extent.The broadband resonance technology exhibits considerable potential in practical engineering applications.

Influences of the Suspension Parameters on the Vehicle Suspension Performance for a Terrain Vehicle

This paper describes an effective methodology for evaluation of the suspension parameters intended to be used for a terrain vehicle. The objective of this approach is to make quick analyses of the sensitivity of the vehicle suspension parameters. For the purpose of developing such a methodology, a mathematical modeling of a quarter vehicles suspension system is developed. Sensitive analysis of the suspension parameters is performed by employing the standard deviation of the vehicle body acceleration, dynamic tire load, and suspension travel. Sensitivity analysis results have shown that the spring stiffness, damping coefficient, tire stiffness and sprung mass have substantial influence on the ride comfort and road holding, while un-sprung mass on the other side has much lower impact in performance of the vehicle suspension system.

A simplified approach for settlement calculation of pile groups considering pile-to-pile interaction in layered soils

A simplified approach is presented for the analysis of the settlement of vertically loaded pile groups. In order to simulate the nonlinear pile-to-pile interaction in pile groups, the soils along the piles are assumed to behave as a series of nonlinear springs subjected to the shaft shear stress at the pile/soil interface. Considering the displacement reduction induced by the pile-to-pile interaction, the shear-deformation method is adopted to approximate the displacement field of the layered soils around the piles, and the equivalent stiffness of the springs is obtained. Furthermore, the load-settlement response of pile groups is deduced by modifying the load-transfer functions to account for the pile-to-pile interaction. The settlements of a laboratory pile groups computed by the presented approach are in a good agreement with measured results. The analysis on Contrastive parameters shows that the settlements of pile group decrease with the increase of the pile space and pile length, and the part of piles exceeding the critical pile length has little contribution to the beating capacity of the pile groups.

Electrical control of antiferromagnetic metal up to 15 nm

Manipulation of antiferromagnetic(AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in[Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction,the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics.

Model updating based on incomplete modal data

The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass and stiffness matrices of an analytical model when only modal frequencies or spatially incomplete modal data are available. While the proposed method is systematic in nature, it also preserves the initial configuration of the analytical model, and physical equality and/or inequality constraints can be easily incorporated into the solution procedure. Numerical examples associated with a simple 5-DoF (degree of freedom) mass-spring system are chosen to illustrate the detailed procedure and the effectiveness of the proposed method. Numerical scenarios ranging from the updating for stiffness terms only to that for all mass and stiffness terms based on various kinds of incomplete modal data are studied. The obtained model updating results are excellent when the measured modal data are noise-free. Uncertainty studies are also conducted based on simulations of corrupted modal data, but a thorough theoretical analysis of the noise effect on the proposed method is still needed.