共查询到19条相似文献,搜索用时 46 毫秒
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国内外对扑翼飞行的气动特性进行了大量研究,这些研究大多基于简谐扑动的刚性翼,然而大量观察发现鸟或昆虫飞行时,翅膀存在明显的柔性变形,这种变形对其气动性能具有显著的影响。该文针对一简化的二维柔性扑翼模型,采用数值求解N-S方程并耦合扑翼柔性变形方程的计算方法,研究了扑翼柔性变形对其气动性能的影响。结果显示扑翼的柔性变形改变了扑翼周围的涡结构,从而影响扑翼的气动性能;适当的柔性变形能延迟前缘涡的脱落,从而有效地改善扑翼的推进效率,但同时减弱了扑翼在低雷诺数环境中产生高升力的尾迹捕捉机制。 相似文献
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热载荷作用下大变形柔性梁刚柔耦合动力学分析 总被引:1,自引:0,他引:1
从非线性应变-位移关系式出发,用虚功原理建立了热载荷作用的柔性梁的热传导方程和旋转刚体-梁系统的刚-柔耦合动力学方程.由于考虑了刚度阵的高次变形项,适用于大变形问题.对温度、弹性变形和刚体运动变量联合求解.研究了热流引起的温度梯度对弹性变形和刚体转动的影响,以及在大变形情况下的几何非线性效应. 相似文献
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考虑了变形产生的几何非线性效应对作大范围运动的平面柔性梁的影响,在其纵向、横向的变形位移中均考虑了变形的二次耦合变量,从非线性应变-变形位移的原理出发,说明增加耦合变量后。使得剪应变近似为零,由此得出的变形模式更符合工程实际和简化需要。考虑两个方向的变形耦合后,采用有限元离散,通过Lagrange方程导出系统的动力学方程。最后对一作旋转运动的平面柔性梁进行仿真计算,并对其固有频率进行分析研究。将本文模型所得的结论。与一次耦合动力学模型、零次近似模型进行比较,说明了三种模型的差异。得到了作旋转运动的平面柔性梁的一些新特点。 相似文献
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摘要:研究了带有附加质量的中心刚体-柔性悬臂梁系统在参数具有随机性时作大范围运动的动力响应问题。基于假设模态法和Lagrange方程建立了带有附加质量的中心刚体-柔性悬臂梁系统的一次近似耦合随机动力学方程,利用混沌多项式结合高效回归法将其转化为完全隐式纯微分方程,求解方程得到柔性悬臂梁变形位移响应的数字特征。最后,通过数值仿真对物理参数和几何参数具有随机性的系统进行动力特性研究。仿真结果表明:利用随机参数的动力学模型能客观地反映出系统的动力学行为;部分随机参数的分散性对柔性体动力响应的影响不可忽视。 相似文献
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某60Si2MnA钢片弹簧在使用10h后出现批量断裂,对断裂片弹簧进行了化学成分分析、硬度测试、金相检验以及断口微观形貌观察,以查明其断裂原因。结果表明:片弹簧断裂是由于在酸洗、电镀过程中析氢反应的发生,使其产生氢脆现象;同时由于热处理工艺过程控制不当,造成组织异常,硬度高于技术要求,加快了其氢脆倾向,最终导致片弹簧在外应力作用下发生氢脆断裂。 相似文献
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透镜面形精度是影响透射式光学系统性能的主要因素之一,支撑结构、自重和热载荷是引起透镜面形发生变化的三个主要原因。为了实现大口径透镜(Φ>200 mm)的高面形精度,本文设计了一种新的基于多点柔性支撑的透镜支撑结构,通过有限元分析,给出该柔性支撑结构下自重和热载荷对透镜面形的影响。分析结果表明:重力作用下透镜上、下表面面形RMS值分别为6.78 nm和3.46 nm;热载荷作用下透镜上、下表面面形RMS值分别为8.30 nm和5.57 nm。由此得出,本文设计的多点柔性支撑结构可以有效减少自重和热载荷对大口径镜面面形的影响,满足透射式光学系统对透镜面形的精度要求(RMS<λ/50,λ=632.8 nm)。 相似文献
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通过断口分析、化学成分分析、金相检验和硬度测试对皮卡车的钢板弹簧断裂的原因进行了分析。结果表明:钢板弹簧表面存在凹坑造成了应力集中,而且板材的非金属夹杂物超标,降低了疲劳强度,在交变应力载荷的作用下,最终造成钢板弹簧发生了早期疲劳断裂。 相似文献
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重卡钢板弹簧断裂失效分析 总被引:1,自引:0,他引:1
通过宏观检查、化学成分分析、硬度测试以及金相检验等结果分析。确定了重型卡车用钢板弹簧的断裂原因。结果表明:因超载使钢板弹簧出现过度反弓,造成板簧卡中的螺栓杆与钢板弹簧动态接触.发生磨损腐蚀,形成凹坑.成为应力集中点;在过大的交变应力作用下.应力集中点萌生裂纹并不断扩展.最终造成钢板弹簧疲劳断裂。最后提出了防止其发生断裂失效的预防措施。 相似文献
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Journal of Failure Analysis and Prevention - Conventional steel leaf spring is analyzed at maximum load using finite element analysis (FEA), ANSYS v16 software. The finite element results showed... 相似文献
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通过化学成分分析、硬度测试、金相检验、断口分析、腐蚀产物及受力情况分析等,对某电厂机组的隔板汽封GH4169弹簧片发生断裂的原因进行了研究。结果表明:弹簧片断裂的性质为应力腐蚀开裂,主要原因为弹簧片运行环境中有大量的腐蚀性介质。 相似文献
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Mazen Mushabab Alqahtani Ashit Kumar Dutta Sultan Almotairi M. Ilayaraja Amani Abdulrahman Albraikan Fahd N. Al-Wesabi Mesfer Al Duhayyim 《计算机、材料和连续体(英文)》2023,74(1):217-233
Recent developments in digital cameras and electronic gadgets coupled with Machine Learning (ML) and Deep Learning (DL)-based automated apple leaf disease detection models are commonly employed as reasonable alternatives to traditional visual inspection models. In this background, the current paper devises an Effective Sailfish Optimizer with EfficientNet-based Apple Leaf disease detection (ESFO-EALD) model. The goal of the proposed ESFO-EALD technique is to identify the occurrence of plant leaf diseases automatically. In this scenario, Median Filtering (MF) approach is utilized to boost the quality of apple plant leaf images. Moreover, SFO with Kapur's entropy-based segmentation technique is also utilized for the identification of the affected plant region from test image. Furthermore, Adam optimizer with EfficientNet-based feature extraction and Spiking Neural Network (SNN)-based classification are employed to detect and classify the apple plant leaf images. A wide range of simulations was conducted to ensure the effective outcomes of ESFO-EALD technique on benchmark dataset. The results reported the supremacy of the proposed ESFO-EALD approach than the existing approaches. 相似文献
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M. Carello A. G. Airale A. Ferraris A. Messana L. Sisca 《Applied Composite Materials》2017,24(6):1493-1508
This paper describes the design and the numerical modelization of a novel transverse Carbon Fiber Reinforced Plastic (CFRP) leaf-spring prototype for a multilink suspension. The most significant innovation is in the functional integration where the leaf spring has been designed to work as spring, anti-roll bar, lower and longitudinal arms at the same time. In particular, the adopted work flow maintains a very close correlation between virtual simulations and experimental tests. Firstly, several tests have been conducted on the CFRP specimen to characterize the material property. Secondly, a virtual card fitting has been carried out in order to set up the leaf-spring Finite Element (FE) model using CRASURV formulation as material law and RADIOSS as solver. Finally, extensive tests have been done on the manufactured component for validation. The results obtained show a good agreement between virtual simulation and experimental tests. Moreover, this solution enabled the suspension to reduce about 75% of the total mass without losing performance. 相似文献
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N. I. Jamadar S. B. Kivade Rakesh Raushan 《Journal of Failure Analysis and Prevention》2018,18(4):782-790
Post-failure analysis of composite structures by damage identification at pre-stage has gained considerable interest in recent years. In the paper, modal flexibility and modal curvature methods have been used for premature failure analysis of composite mono leaf spring through analytical and finite element approaches. Initially, finite element model of healthy and cracked spring is used to evaluate the eigenvalue and eigenvectors. Subsequently, change in flexibility and absolute curvature difference among both springs are evaluated after mass normalization. The presence, location and severity of crack in a spring are identified through differences in local flexibilities and change in absolute modal curvatures. The modal curvature method predicts location and severity of crack more precisely than the modal flexibility method. 相似文献
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目的 为了简化码垛机抓手机构,并解决码垛机抓手夹持机构对称性的问题.方法 在查阅文献的基础上设计一种高位码垛机抓手的夹持机构,并从机构对称性角度出发,建立夹持机构的数学模型,采用基于AIWF的粒子群优化算法对机构参数进行数值优化.结果 优化后抓手的最大对称性偏差从1.0423°降低到0.4113°,优化效果明显.在Adams软件中建立了相应的样机模型,通过仿真分析验证了数值优化结果的正确性.结论 设计的码垛机抓手机构简洁,对称性好,实际应用效果好. 相似文献