共查询到19条相似文献,搜索用时 185 毫秒
1.
2.
3.
4.
5.
为了提高电动汽车乘坐舒适性,为电机结构设计优化提供理论依据,对车用永磁同步电机电磁噪声特性进行分析。以某峰值功率为230 kW的72槽12极车用永磁同步电机为研究对象,开展电磁噪声仿真及优化研究:鉴于电磁噪声的主要产生原因为径向电磁力及多物理场耦合,提出基于电磁和结构弱耦合有限元法的模态分析方法;以电磁力、齿槽转矩、峰值转矩作为优化目标,提出基于遗传算法的多目标优化方案。在转速2 800 r/min工况下进行模态分析与试验,定子总成模态频率相对误差小于5%,验证了仿真方法的准确性。进行多目标优化后,噪声试验整体声压级最大值为70.5 dB(A),相比优化前的85.6 dB(A)降低了17.64%。 相似文献
6.
立足有限元基本理论,利用ANSYS有限元软件构建大型风力发电机组钢—混塔筒模型,开展模态分析,考察预应力和地基刚度对钢—混塔筒结构模态频率的影响。研究发现:当地基刚度由80GNm/rad增大到240GNm/rad时,钢—混塔筒结构前三阶模态频率的增大幅度分别是10.680%、20.230%和7.546%,增幅较大,不容忽视;钢—混塔筒结构第一阶模态频率(自振基频)在风力发电机组设计中是一个非常重要的设计参数,且受预应力钢筋影响较大,施加预应力比不施加预应力时增大20%以上;钢—混塔筒结构第二、三阶模态频率受到预应力影响较小,仅为1.5%左右,在实际设计生产过程中可不予考虑。 相似文献
7.
经验模态分解在切削振动信号分析中的应用 总被引:1,自引:0,他引:1
为了分析切削振动的变化规律及产生根源,采用在线监测的方法采集振动信号,提出了运用经验模态分解对振动信号进行分析的方法,构建了分段频率变化的仿真振动信号,分别对仿真振动信号进行短时傅里叶变换、小波变换和经验模态分解时频分析。结果表明,经验模态分解方法具有更高的时频分辨率,运用经验模态分解方法对实际振动信号进行分析,提取典型分量绘制希尔伯特幅值谱,能较好地反映振动信号的时频变化规律。经验模态分解适合对切削振动信号进行分析,但是需要对算法的模态混叠及计算效率低等不足进行完善。研究结果对非平稳信号的分析具有参考价值。 相似文献
8.
基于直齿圆柱齿轮的动态分析和优化设计的需要,运用ANSYS有限元分析软件建立其三维实体模型,并对该齿轮振动特性的模态进行分析,得到了结构的低阶模态频率和振型分布,对齿轮的动态分析和优化设计提供理论指导。 相似文献
9.
10.
11.
This article explains how embodied cognition and perceptual symbol systems enable product designers to influence consumers by communicating key perceptual features through subtle changes in product design elements. In this way, managers can change perceptual design elements to support line extension strategies. More specifically, design changes can be used as a tool to help evolve consumer perceptions of a product's uses and brand category membership. The role of perceptual symbols in product design is illustrated by a well‐known off‐road motorbike brand that planned to extend into the street motorbike segment. In order to facilitate consumer acceptance of a street motorbike from this off‐road brand, the firm gradually introduced models containing an increasing number of elements of street motorbikes over a period of several years. The authors use this example to show how typical design elements of the target product category can be effectively integrated with design elements of the current product category by simply modifying key characteristics of product‐shape attributes. This process is further tested in an experiment, where motorbike models differing slightly in key product features (e.g., product shape) were rated on their resemblance to street or off‐road motorbikes. The results show a strong effect of these design changes on brand‐category membership. Managerial implications of this approach and future research directions are discussed. 相似文献
12.
为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。 相似文献
13.
利用ANSYS Workbench软件对2kW的风力机进行流固耦合分析,得到风场风速、叶片所受风压、叶片变形、应力应变等有限元分析结果。同时对叶片本身、叶片在风场中静止及旋转情况下进行模态分析,并进行比较。ANSYS已将流体软件CFX整合到Workbench中,利用Work-bench对风机进行流固耦合分析可在软件内部完成多物理场数据传递,方便实用。得到的风场信息、叶片应力云图及叶片的模态分析为叶片的优化设计及研发工作提供直接数据,从而减少产品开发周期,降低开发成本。 相似文献
14.
监控量测是在隧道施工过程中,对围岩和支护系统的稳定状态进行监测,通过拱顶下沉量测、格栅钢架内外力监测、锚杆轴力测试,将量测数据进行处理和分析,绘制时间-位移曲线,为喷锚支护和二次衬砌的参数调整提供依据,把量测的数据经整理和分析得到的信息及时反馈到施工中,以便根据检测数据灵活、及时地处理施工中出现的各种问题,确保工程质量和进度。 相似文献
15.
为了研究流固耦合作用对球罐地震反应的影响,利用ABAQUS软件建立1 000m3球罐有限元模型。采用子空间法对球罐进行了模态分析,并与规范算法进行对比,同时采用耦合拉格朗日欧拉算法,对考虑液固耦合作用的球罐进行地震反应分析。分析结果表明:考虑液固耦合作用使球形储罐的顶点位移、竖向支反力、支柱底部剪力以及拉杆应力等方面衰减得更快,并且在数值上也比附加质量法所模拟的结果小很多。在此基础上,介绍了子结构拟动力试验方法,提出将子结构拟动力试验方法应用于球形储罐的抗震性能分析,阐述了球形储罐子结构拟动力试验的步骤,为球形储罐抗震研究提供一种新的试验研究思路。 相似文献
16.
从行业偿债来源入手,从债务安全性的角度探讨行业的信用风险水平,力图针对行业偿付现有债务以及未来债务的能力给出量化的分析。提出了信用评级视角的行业信用风险分析方法框架,采用该分析框架对我国煤炭采选行业进行了行业信用风险评价。结果表明,该框架的分析结论与煤炭行业在债券市场的实际表现互为印证。 相似文献
17.
18.
《Food Policy》2014
This article addresses which food security frames can be identified in the Common Agricultural Policy (CAP) post-2013 reform process, and which actors deploy particular food security frames. The concept of frames refers to relatively distinct and coherent sets of meaning attributed to a concept, such as food security. The article shows that in the European Union (EU) food security is a consensus frame which can be broken down in six conflicting and overlapping sub-frames and which has complicated the debates about the future of the CAP. We demonstrate that during the CAP-reform debates of 2009–2012 a variety of food security arguments were deployed by a broad range of stakeholders, who attached different meanings and made different claims about the relationship between the CAP and food security. Inductive frame analysis reveals that the consensus frame of food security can be broken down into six conflicting and overlapping sub-frames: (1) the productionist frame, (2) the environmental frame, (3) the development frame, (4) the free trade frame, (5) the regional frame, and (6) the food sovereignty frame. Each of these frames was invoked by a specific group of stakeholders, whereby the productionist and environmental frames were deployed most often. The European Commission, meanwhile, invoked various frames at the same time in its communications. As a result of these various framings of the relationship between the CAP and food security, a clear political vision on this relationship is lacking. We conclude that politicians and policymakers may need to develop a coherent vision on what food security entails, and on how the CAP could contribute to both European and global food security. 相似文献