共查询到19条相似文献,搜索用时 130 毫秒
1.
为提升汽车发动机油底壳动刚度,减少其振动噪声,对其动力学性能进行优化.利用Solid Works设计某型号油底壳初始模型,采用Abaqus分析其模态和频率响应,并根据分析结果对原始模型进行优化设计.优化后的汽车发动机油底壳结构动力学性能显著提升. 相似文献
2.
3.
为给火箭系统结构振动响应分析提供有效载荷,采用雷诺平均N S(Reynolds averaged N S,RANS)方程求解喷流流场与用非线性声学求解器(Non linear Acoustics Solver,NLAS)求解喷流声场相结合的方法,对某高超声速火箭液体发动机喷流噪声进行数值模拟.用有限元法和统计能量分析相结合的方法,求解发动机模型在噪声作用下的全频段振动响应.计算结果表明:发动机喷流噪声声压级大小与喷流流场的湍流动能密切相关,湍流强度大的位置喷流噪声声压大;喷流流场初始段混合层内产生的噪声在高频段大于过渡区内产生的噪声,但中低频段却相反. 相似文献
4.
5.
使用具有指数相关性的色噪声近似外界环境干扰,研究色噪声激励下驰振能量采集器(GEH)的稳态响应.首先,介绍了系统的理论机电耦合运动方程,并对其进行无量纲化处理.其次,通过广义谐波变换对方程进行等效解耦,然后使用能量包线随机平均法得到系统稳态响应的解析解.最后,使用四阶龙格库塔算法进行数值模拟,在验证解析解有效性的同时分析了风速、色噪声参数对系统稳态响应的影响.研究结果表明,较大的噪声强度有利于提升系统的能量采集性能,且在风速较低时效果更明显;噪声相关时间对系统稳态响应的影响与噪声强度相反.当系统的振动模式由风激励主导时,系统的响应表现为带有附加噪声的周期性振动;随着风速增加,增强的风激励削弱了色噪声激励对系统稳态响应的影响.此外,本文还研究了系统结构参数和电气参数对平均输出功率的影响,研究结果为优化系统设计提供了有效的理论指导. 相似文献
6.
使用具有指数相关性的色噪声近似外界环境干扰,研究色噪声激励下驰振能量采集器(GEH)的稳态响应.首先,介绍了系统的理论机电耦合运动方程,并对其进行无量纲化处理.其次,通过广义谐波变换对方程进行等效解耦,然后使用能量包线随机平均法得到系统稳态响应的解析解.最后,使用四阶龙格库塔算法进行数值模拟,在验证解析解有效性的同时分析了风速、色噪声参数对系统稳态响应的影响.研究结果表明,较大的噪声强度有利于提升系统的能量采集性能,且在风速较低时效果更明显;噪声相关时间对系统稳态响应的影响与噪声强度相反.当系统的振动模式由风激励主导时,系统的响应表现为带有附加噪声的周期性振动;随着风速增加,增强的风激励削弱了色噪声激励对系统稳态响应的影响.此外,本文还研究了系统结构参数和电气参数对平均输出功率的影响,研究结果为优化系统设计提供了有效的理论指导. 相似文献
7.
基于声灵敏度的车身拓扑优化 总被引:1,自引:0,他引:1
为探讨板件结构对车内噪声的影响,建立某商务车的白车身有限元模型,分析其模态和车身声灵敏度,确定对汽车低频振动和噪声影响较大的板件;结合变密度法在整车环境下对板件进行减振降噪的拓扑优化,根据拓扑优化结果对板件进行结构修改. 优化后的车身声灵敏度曲线与原车身声灵敏度曲线相比,低频范围内的峰值都有不同程度的降低,表明结合整车动态响应的汽车板件结构拓扑优化可以有效降低车内低频振动噪声. 相似文献
8.
9.
10.
针对BP神经网络和支持向量机对整机振动故障诊断时的低效问题,提出了一种基于多类协同训练的航空发动机整机振动故障诊断方法.引入逻辑回归算法构建初始故障分类器,设计了一种新的属性划分算法来迭代优化故障分类器,基于优化后的故障分类器进行故障类别预测,并使用多数投票机制进行故障仿真识别.实验采用某航空发动机整机振动数据作为样本数据集,并从中选择80%的数据用于训练,20%的数据用于测试,同时验证了在噪声信号的干扰下该方法对故障数据的诊断准确性.结果表明,该方法可有效降低噪声信号对故障诊断结果的影响,且诊断准确性高,具有重要的工程实用价值. 相似文献
11.
Bead pattern optimization 总被引:1,自引:1,他引:0
Plane sheet panels exhibit poor stiffness and NVH (noise, vibration, and harshness) performance due to their flexibility. A common and cost-effective approach in the automotive industry to improve the stiffness and NVH peformance of sheet panels is the addition of beads. However, no systematic methodology is available for determining the optimal pattern of beads in sheet metal. This research explores the feasibility of applying topology optimization methods to the bead design of sheet panels. The approach starts with adding beam elements to the shell element model of the sheet panel to simulate the stiffness improvement of the structure and then uses the topology optimization method to obtain the optimal layout of the beam elements. A cantilever plate is used to perform a preliminary study for bead pattern design and a simplified vehicle structure is used to demonstrate the applicability of the proposed method. 相似文献
12.
The perception of vehicle ride comfort is influenced by the dynamic performance of full-depth foam used in many vehicle seats. The effects of the thickness of foam on the dynamic stiffness (i.e., stiffness and damping as a function of frequency) of foam cushions with three thicknesses (60, 80, and 100 mm), and the vibration transmitted through these cushions at the seat pan and the backrest were measured with 12 subjects (6 males and 6 females). With increasing thickness, the stiffness and the damping of the foam decreased. With increasing thickness of foam at the seat pan, the resonance frequencies around 4 Hz in the vertical in-line and fore-and-aft cross-axis transmissibilities of the seat pan cushion and the backrest cushion decreased. For the conditions investigated, it is concluded that the thickness of foam at a vertical backrest has little effect on the vertical in-line or fore-and-aft cross-axis transmissibilities of the foam at either the seat pan or the backrest. The frequencies of the primary resonances around 4 Hz in the vertical in-line transmissibility and the fore-and-aft cross-axis transmissibility of foam at the seat pan were highly correlated. Compared to sitting on a rigid seat pan with a foam backrest, sitting with foam at both the seat pan and the backrest reduced the resonance frequency in the vertical in-line transmissibility of the backrest foam and increased the associated transmissibility at resonance, while the fore-and-aft cross-axis transmissibility of the backrest was little affected. Compared to sitting without a backrest, sitting with a rigid vertical backrest increased the resonance frequency of the fore-and-aft cross-axis transmissibility of the seat pan cushion and increased the transmissibility at resonance.Relevance to industryThe transmissibility of a seat is determined by the dynamic properties of the occupant of the seat and the dynamic properties of the seat. This study shows how the thicknesses of foam at a seat pan and foam at a backrest affect the in-line and cross-axis transmissibilities of the foams at the seat pan and the backrest. The findings have application to the design of vehicle seats to minimise the transmission of vibration to the body. 相似文献
13.
在研究光盘驱动器隔振技术基础上,使用ADAMS专用仿真软件对光盘驱动器隔振系统进行了仿真,并对整个仿真系统进行了优化,优化结果表明系统的性能有了很大的提高,优化后的最大振幅是优化前的62.29%,优化后消除振动所需时间为优化前的18.18%。 相似文献
14.
Kumar S 《Applied ergonomics》2004,35(6):509-520
The objective of this study was to determine if the vibration in sagittal (x), coronal (y) and vertical (z) axes of the seat pan of the heavy haul trucks used in overburden mining, and the vibration experienced by the drivers at the third lumbar and seventh cervical vertebral levels in operating these trucks exceeded the ISO standards, thereby posing threat to safety. A new and an old truck of two different makes and different carrying capacities (200 and 300 series) were instrumented with a triaxial accelerometer on the seat pan. Fourteen drivers (8 male and 6 female) were instrumented with a triaxial accelerometer at C7 and L3 spinous processes. The vibration at the seat pan, C7, and L3 levels were recorded using an onboard computer with PCMCIA card and, compared against the ISO standards. The vertical vibration of the seat pan in the entire sample ranged from a low of .37 m/s2 to a high of 11.73 m/s2. The vibration at the lumbar level in the sample ranged between .34 and 2.72 m/s2. The values for cervical level vertical vibration in the sample ranged between .2 and 2.22 m/s2. The gender of the driver, truck make, and it's carrying capacity did not have a significant effect on the vibration. However, the body weight of the driver, the segment of the truck and the site of measurement revealed significant differences in vibration (p<0.001). Out of a total 36 combinations (4 trucks×9 recording locations) the seat pan vertical vibration exceeded the ISO standards 8 times for males and 9 times for females. The lumbar vertebral vertical vibration in males exceeded ISO standards 12 times and in females 11 times. The cervical vertebral vertical vibration exceeded ISO standards once in females only. However, in sagittal and coronal planes the whole body vibration exceeded the ISO standards many times. Heavy haul trucks (240 and 320 ton capacity) frequently generated vibrations in excess of ISO standards in overburden mining operation representing a health hazard. 相似文献
15.
依据齿轮啮合动态激励基本原理和弹性流体动力润滑理论,建立同时追求
齿轮啮合时变刚度激励最小、齿间最小油膜厚度最大(倒数最小)及齿轮传动总体积最小的
约束多目标优化设计数学模型。对现有的用于两目标优化设计的粒子群优化方法加以改进,
给出了约束3 目标优化设计方法。利用Matlab 编制优化程序,并对范例进行分析计算。优
化过程及结果表明,采用较多的齿数,在小于1 的范围内采用较大的正变位系数,适度采用
较大的压力角可以增大轮齿啮合综合刚度谱图中基频谐波的幅值,有效地提高齿轮传动系统
抵抗内部激励振动的能力及性价比。 相似文献
16.
本文将负刚度元件集成到惯容型非线性能量汇中构成负刚度惯容型非线性能量汇,并将此装置应用到整星结构,讨论其减振效果.基于最大幅值减振百分比展示了负刚度惯容型非线性能量汇的减振性能,并通过对比讨论了负刚度元件对惯容型非线性能量汇减振性能的影响.最后讨论了负刚度惯容型非线性能量汇的参数影响及其优化.研究结果表明,作用于整星系统中的新型负刚度惯容型非线性能量汇具有很好的减振性能. 相似文献
17.
18.
Changes in the seating condition may change the body posture which could affect the transmission of vibration through a vehicle seat. This study investigates the effect of different seating conditions on the transmission of vibration through a car seat. Ten male subjects sat on the passenger seat of a sedan car driven at 60 km/h adopting one of six conditions at a time. The VDV was measured on the seat and backrest. Backrest contact affected the VDV measured on the seat pan in the z- and y-axis only. Increasing the backrest angle increased the VDV at the backrest in the x-direction and reduced the VDV at the backrest in the z-direction. With the increase in the backrest angle, the total VDV at the backrest became higher than the total VDV on the seat pan. The study showed no effect of foot position and contact with a headrest on the VDVs.Relevance to industryThis research presents the effect of the seating condition on the transmission of vibration through the seat pan and backrest of a car seat. Research of this kind may help seat manufacturers recommend seating conditions that reduce discomfort caused by whole-body vibration. 相似文献
19.
Suzanne D. Smith Jeanne A. Smith David R. Bowden 《International Journal of Industrial Ergonomics》2008,38(5-6):434-446
The multi-axis vibration transmission characteristics of selected suspension seats were investigated in the laboratory. Subjects were exposed to a flat acceleration spectrum and two low frequency signals extracted from multi-axis acceleration data recorded at the floor of a passenger locomotive. Triaxial accelerations were measured at the floor of the vibration table and at the interfaces between the subject and mounted seat (seat pan and seat back). The transmission ratios between the overall seat pan and seat back accelerations and floor accelerations provided an effective tool for evaluating the effects of measurement site, vibration direction, and posture among the selected seating systems. The results showed that the system transfer matrix, estimated using a multiple-input/single-output model, would be less than ideal for predicting low frequency operational seat vibration when using suspension seats. The Seat Effective Amplitude Transmissibility (SEAT), estimated for the tested locomotive seats, was used to predict the weighted seat pan accelerations and Vibration Total Values for assessing a 1-h operational exposure in accordance with ISO 2631-1: 1997.
Relevance to industry
Multi-axis SEAT values can be estimated for seating systems tested in the laboratory using representative operational exposures. These values can be applied to monitored vehicle floor accelerations to target potentially harmful vibration in accordance with ISO 2631-1: 1997, assuming the operational exposures have similar frequency and magnitude characteristics. The transmission at the seat back should be considered when substantial low frequency multi-axis vibration is present. 相似文献