汽车车门密封性能控制与风噪声改善

汽车车门密封性能是整车风噪声水平的重要影响因素,分析汽车车门主要部件密封机理,提出相应泄漏控制方法;结合某款SUV车型后侧窗风噪"泄漏声"问题,通过车门密封优化,消除异常风噪声,主观评价及客观测试均达到改善目标。     

汽车车门把手气辅成型工艺CAE优化研究

目的 针对传统汽车车门把手成型工艺在实际应用中塑件收缩变形量大、无法有效控制等问题,开展汽车车门把手气辅成型工艺优化研究。方法 通过确定基于计算机辅助工程的塑件成型方式、设置改造后汽车车门把手塑件结构、优化注塑和注气参数,提出一种针对汽车车门把手气辅成型的工艺优化方案。结果 与优化前成型工艺相比,采用优化后成型工艺得到的汽车车门把手塑件的收缩变形量明显降低,汽车车门把手塑件的收缩变形量均能够控制在0.45%以下。结论 引入计算机辅助工程优化分析技术对实现汽车车门把手整体制件结构设计具有更高的实际应用价值,有利于提升汽车车门把手设计、生产和加工的效率。     

某车车门关闭声品质评价

汽车车门声品质是汽车声品质研究的重要内容。首先对所采集的车门关闭声音样本进行主观评价实验,并运用Bradley-Terry模型对声音样本偏好性进行分析。然后通过Head Artemis软件进行时频域分析、滤波分析和计算响度、尖锐度等心理声学参数对声音样本做出客观评价。     

汽车镁质复合仪表板传声损失的实验及仿真研究

复合板可以有效地提高结构的隔声性能,因此镁合金复合结构已成功应用于汽车仪表板。以Biot-Allard模型为基础,建立敷设吸声材料的复合结构仪表板模型,利用结构-声耦合法,计算仪表板的传声损失。通过与实验结果比较,采用结构-声耦合法预测结构的隔声性能是可行的。结果表明,低频范围内的隔声性能对仪表板的边界约束情况十分敏感,可通过提高仪表板边界的连接刚度来提高其传声损失。中高频范围内,敷设多孔吸声材料可以提高仪表板的隔声性能。但厚度增加并不能无限制的提高其传声损失,还要考虑成本与低频"隔声恶化"的问题。因此,需合理选取吸声材料的厚度,使得仪表板在关心的频带内声学性能达到最优。     

扭转振动压电超声换能器的研究

用声强技术检测区分板壳结构的空气传声与结构传声时，结构的辐射效率之差决定了检测结果的可信度，文中分析了实际结构的在声场激励下的实测辐射效率与无限大结构的空气传声辐射效率之差，及对区检测结果的影响。实验结果证实了理论分析。     

区分空气传声和结构传声的研究

降低飞机舱内的噪声首先要弄清引起舱内噪声的主要来源,以便采取合理有效的降噪措施。进入飞机舱内的噪声一般可分成两大类:空气声激励和机械激励下舱壁的声辐射。前者对舱内声场的贡献称为空气传声,后者称为结构传声。本文根据飞机壁板在机械激励和声场激励时,声辐射系数的差异,借助声强方法推导出两种不同激励下壁板辐射声功率的区分公式,并利用这些公式分别对均匀平板和加肋板进行了区分空气传声和结构传声的实验,计算区分结果和实验结果吻合较好。     

100%低地板列车车内噪声传递特性分析EI北大核心CSCD

基于线路试验,测试分析了100%低地板列车车内噪声特性,研究了车内噪声源分布以及空气传声、结构传声路径对车内噪声的贡献。使用统计能量法建立了单节车车内噪声预测模型,并利用其获得了车内噪声的功率输入贡献率,在此基础上提出了车内减振降噪建议措施。试验和仿真结果表明,虽然低地板列车的转向架位于车厢中部,但是车内噪声仍然表现为两端大、中间小的趋势。车内噪声显著频段为中心频率250-2 000Hz的1/3倍频带,主要噪声源位于地板和风挡区域,主要是轮轨区域噪声。客室两端噪声主要经由车下地板和风挡结构传递至车内,客室中部噪声主要经由车下地板结构传递至车内,噪声传递路径为空气传声。因此,提高地板、风挡的密封和隔声性能是降低车内噪声的有效方法。相关研究结果可为100%低地板列车车内减振降噪提供参考。     

热成形金属复合材料的微观结构及力学行为研究

对汽车车门防掩梁热成形(成形与淬火同时进行)过程进行了研究,发现由于成形过程中钢材表面发生氧化脱碳,得到的防撞梁零部件表面软而内部硬,材料性质在厚度方向上呈连续梯度分布,即表面硬度、强度低而内部的硬度、强度高,这样形成了新型连续梯度分布的多层金属复合材料.对汽车车门防撞梁这种新型金属复合材料的微观结构、硬度、强度及塑性...     

结构—声耦合法在汽车仪表板隔声性能仿真分析中的应用

镁合金材料具有密度小、比刚度高、阻尼大、抗冲击性好等优势,已成功用于汽车仪表板。应用结构-声耦合法分析仪表板的隔声性能,可避免传统理论求解对模型的苛刻要求和实验条件的限制。通过与实验结果比较,证实结构—声耦合法预测结构隔声性能的可靠性,并得出了扩散声场内汽车仪表板传声损失的数值结果。结果表明,在低频段,相同面密度的压铸镁合金仪表板的隔声性能明显优于钢质仪表板。换用轻质镁合金材料后,需改进原有的结构,使仪表板的固有频率避开噪声源的峰值频段,避免结构在某些频段内的声学特性恶化。采用镁合金材料可在满足汽车减重要求的同时,改善驾驶室内的声学环境。     

汽车声学密封性能检测

首先基于已知蜂鸣器声源的识别结果检验波束形成的声源识别准确性,在此基础上,利用波束形成声源识别方法检测某汽车的声学密封性能,结果表明：右侧前车门后下部区域、后侧挡风玻璃是该汽车声学密封性能薄弱环节,为该车的声学密封性能改善指明方向,对降低车内噪声、改善其乘坐舒适性具有重要意义。     

飞机舱门密封结构的气密可靠性研究

采用可靠性思想分析飞机舱门密封结构参数对密封性能的影响。对两种型号的舱门密封带进行整体规格的压缩实验,拟合成Ogden模型代入有限元计算获得门体与门框的二次接触力的隐式响应关系。将关门行程、装配尺寸、挡件尺寸等视为随机变量,采用Monte Carlo法对两种密封带的气密可靠性进行比较,得到了密封结构参数的均值灵敏度和方差灵敏度,对舱门密封带选型与结构的优化设计提供参考。     

钠燃烧试验厂房隔热密封门的设计与分析

钠燃烧过程会造成试验厂房内的温度和压力显著升高.试验厂房的门作为厂房边界的一部分,应具备防火隔热和承压密封的功能,但在目前的实际应用中并没有可以满足该要求的工程门.基于此,针对钠燃烧过程的特点,并结合核工程的实际工况,设计了一种兼具防火隔热和承压密封功能的新型隔热密封门.以核工程中不同工况下常用工程门的结构为基础,结合...     

Vakuum‐Lineardurchführungen mit Magnetflüssigkeitsdichtungen

Vacuum linear feedthroughs with magnetic fluid seal A magnetic fluid sealed feedthrough is a device that transmits linear motion into a vacuum chamber with minimal frictional resistances and minimal contamination level.They are widely employed in high and ultra‐high vacuum equipment among others in semiconductor fabrication industry and robotics applications. The operating conditions of magnetic fluid seals during reciprocating motion are so different from those with rotating motion that the use of their conventional structures for reciprocating motion seals yield no good results. Analysis of sealing mechanism of magnetic fluid seal in reciprocating motion shows that the operation of these seals is affected by the carry‐over and the magnetic fluid deformation in the sealing gap, which depends on the velocity of reciprocating motion. The reduction of magnetic fluid quantity in the sealing gap,caused by the reciprocating motion of the shaft is reason of the seal failure. In the paper a short characteristic of magnetic fluid sealing technology , principle of sealing, behaviour of the ferrofluid and seal failure mechanism in the linear motion of the shaft are given. Moreover some new structure designs of vacuum linear feedthroughs with magnetic fluid seals, which have practical application value are presented.     

离心式压缩机密封动态特性分析及稳定性评价

稳定性问题是离心压缩机在向高端化方向发展过程中遇到的主要瓶颈,密封间隙内流体周向流动导致的压力在圆周方向不均匀分布是导致失稳的主要原因。采用数值模拟的方法预测密封的动力特性系数,有助于加强对密封机理的理解,实现密封结构的优化进而提高转子的稳定性和设计的可靠性。本文使用数值模拟的方法,首先基于ANSYS APDL语言,开发了参数化程序来构建迷宫密封、孔式阻尼密封及蜂窝密封的几何模型,采用ANSYS CFX软件,计算并比较三种密封的刚度及阻尼等动力学特性参数,研究结果表明孔式阻尼密封及蜂窝密封相对于迷宫密封可以提供更大的刚度和阻尼、且具有较好的密封特性。在此基础上,以孔式阻尼密封为对象,研究比较了不同孔间距,不同孔径的孔式阻尼密封,找到影响阻尼密封动力学参数的基本规律。最后以一台九级合成气压缩机转子为例,比较不同密封对转子稳定性的影响。CFD计算的结果预测了密封的动力特性以及密封结构参数对转子动力学特性的影响,可以指导密封的设计和压缩机改造,综合考虑性能和制造成本,实现优化设计。     

Numerical and experimental evaluation of performance of centrifugal seals

‘Centrifugal seals’ or ‘Slinger seals’ offer an attractive choice as non-contact-type sealing in fluid machinery. These seals utilize the radial pressure gradient caused by centrifugal forces in a rotating fluid ring, to create a sealing of the working fluid. Basic construction of a typical seal consists of a rotating disc inside a stationary casing; one side of the disc (sealing side) is provided with a set of slots (Type-1) or vanes (Type-2) to enhance the tangential velocity of the fluid. The other side of the disk (back side) in both the configurations is exposed to high pressure liquid being sealed. Both numerical and experimental investigations of the performance of Type-1 seal (with slots) have been carried out so as to optimize the seal configuration to achieve maximum sealing capacity, with minimum power consumption. A comparison of the performance of Type-1 seal has been made with that of conventional one (Type-2) in view of economy of construction and better sealing with minimal expense of power consumption. A test rig that allows for varying the major geometrical and operating parameters was designed and tests were conducted with water as the medium. Influence of major geometric parameters like dimensions and number of slots, axial/radial clearances and major operating parameters like rotational speed, inlet pressure and sealing fluid bypass flow rate has been investigated. Apart from various pressure, temperature, flow and torque measurements, the interface between the sealing and working fluid for the experiments was captured and recorded using a high speed camera at ~26,000 frames per second. Geometrical configuration for the slots that maximizes the sealing capacity is arrived through 3D numerical simulations using commercial CFD solver ANSYS Fluent^®. A good agreement is obtained with respect to experimental results. In view of economy of construction and better sealing with minimal expense of operating power, a modified version of Type-1 seal termed as Type-3 seal is investigated. A simple 1D model for prediction of the interface radius during the seal operation, which could be used as a quick design guide, is also presented.     

偏心率和转速对迷宫密封力和动力学参数影响分析研究

通过数值方法和商用CFD(计算流体动力学)软件对密封-转子系统进行建模和求解,研究了5种偏心率和5种转速下的计算机求解时间、流场压力分布、密封力的变化情况,并对泄漏量影响分析和迷宫密封动力学参数影响进行分析研究。研究结果表明:该方法能较好地模拟计算迷宫密封泄漏量和动力学参数,得到腔室压力随着偏心率增大而增大,密封切向力随着偏心率、转速的增大而增大,密封径向力随着偏心率、转速的增大而负向增大;通过密封长度、密封间隙、密封压差对泄漏量影响计算,三者变化率分别为6.62%,65.21%和69.97%,表明密封间隙和压差变化是影响泄漏量变化的重要影响因素;通过密封压差和密封长度对动力学参数影响分析,得出增大密封压差和密封长度不利于系统稳定、增大密封间隙会使得系统趋于稳定。     

Peelable seam systems and their production

In packaging, heat-seal seams have been known as ‘peelable seals’ for a long time. In this system seal medium A is sealed with seal medium B. They are combined in such a way that the sealed seam can be reopened by a defined force without destroying the packaging. Typical applications for peelable seals are boxes or containers with sealed cover sheets, blisters and flexible packagings. The tendency towards peelable packagings has increased recently. This research project dealt with the relevant processes and parameters that influence peelable seals and aims to define reproducible, peelable sealed seams and to elaborate upon a method to develop and produce peelable seam systems. Compared with other research programmes or bibliographical data, this project dealt, in particular, with:

• i the definition of a ‘reproducible, peelable sealed seam’;
• ii an analysis of peelable seam production using the different sealing techniques (heat-contact, ultrasonic and inductive high-frequency);
• iii the influence of the type of sealer jaw on the production and characteristics of peelable seams.

     

液膜密封振动及冲击动力学特性

液膜密封运行过程因工况瞬时变化、系统振动及润滑不足等因素易引发端面接触冲击,严重影响密封寿命。建立考虑端面接触的液膜密封动力学模型,采用直接数值求解方法对运动方程、质量守恒空化边界雷诺方程、微凸体接触方程在全时间域内耦合求解,研究了液膜空化、轴向扰动及运行工况瞬变对密封稳定性与冲击特性的影响。结果表明:液膜空化有效提高了系统抗干扰能力,膜厚越小,受扰动后震荡频率越大且恢复至稳定状态的时间越长;发生端面冲击时膜厚振动频率显著大于全液膜状态下所受扰动情况。随转速及密封腔压力变化值的不断扩大,接触载荷值及冲击频率均不断增大,冲力响应越显著,在端面接触发生瞬间有明显的速度方向突变。     

汽轮机叶顶汽封泄漏涡诱导下的压力脉动研究

以某汽轮机级为研究对象,采用三维非定常数值模拟的方法,研究了动叶顶部汽封泄漏涡的涡动特性和泄漏涡影响下汽封腔室内的压力脉动规律。结果表明:叶顶汽封腔室内存在周向螺旋状涡与壁角涡组成的多尺度涡系,涡系的位置和影响范围会随时间经历复杂的变化。叶顶汽封腔室内的压力脉动频率中兼具叶轮旋转的周期性频率和溃散为小尺度涡结构后的高频率。间隙内的多尺度涡结构和动静叶间交替变化的压力场在汽封间隙内的传播是引起汽封腔室内周向压力不均的主要原因。     

Seal bond characterization of laminated plastic food cups by scanning electron and optic microscopes

Heat seals of laminated semi‐rigid food cups were evaluated to characterize the seal bond. Laminated lidding material was sealed at temperatures of 160–180°C to thermoformed cups. Various seal regions of the cups with different ultrasonic signal strengths (%) were sectioned at the rim and examined using optical and scanning electron microscopes (SEM). Ultrasonic signals were able to pinpoint seal defects; however, the magnitude of the signals did not relate to the actual seal condition or seal quality affected by the sealing process. This was attributed to the very short seal width and non‐parallel surface of the heat seal, which possibly resulted in signal loss by reflection and scattering from the seal surface. C‐scan of ultrasound, SEM and optical microscopic images provided the information that the heat‐sealing process was unstable, due to insufficient and non‐uniform heat‐seal temperature or pressure, misalignment of the sealing jaws or non‐parallel sealing or cutting unit configuration. Copyright © 2004 John Wiley & Sons, Ltd.