共查询到18条相似文献,搜索用时 986 毫秒
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叶片型面具有曲率突变特性,需进行分区域加工,其微结构区域的精确识别和抛磨路径拼接是提高叶片表面质量一致性的关键。针对此类问题,提出一种依据截面线切向量夹角变化识别前、后缘微结构区域,根据截面线法向量配准识别叶根过渡圆弧微结构区域的方法,即根据百叶轮最大加工带宽度和抛磨点匹配法分别实现前、后缘和叶根过渡圆弧微结构区域与叶盆、叶背抛磨路径的拼接。仿真及实验结果表明,该方法相较传统圆弧识别方法,能更有效保留微结构区域轮廓信息,相比未考虑路径拼接的抛磨方式,抛磨后叶片型面轮廓精度提高 49.52%,表面粗糙度提高 57.31%,加工质量一致性提高 7.15%和 11.55%,证实了微结构区域的识别及路径拼接可有效提高叶片加工质量的一致性。 相似文献
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圆柱斜齿轮动态强度与疲劳损伤仿真 总被引:1,自引:1,他引:1
为更好满足使用要求,对圆柱斜齿轮进行精确设计与加工,利用非线性有限元仿真软件MSC Marc对圆柱斜齿轮动态啮合过程齿面接触应力和齿根弯曲应力变化规律进行研究,利用疲劳分析软件MSC Fatigue对轮齿齿根弯曲疲劳寿命进行仿真计算,并根据设计寿命计算出安全寿命系数,为齿轮设计提供理论依据. 相似文献
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植物叶片轮廓特征提取方法研究 总被引:1,自引:0,他引:1
根据植物叶片形态特征中锯齿和叶裂的重要性,设计了基于链码的研究方法。通过对叶片图像预处理得到叶片的轮廓曲线、结合基于链码的拐点检测方法和基于链码差的边界凹凸性判别方法确定锯齿点和叶裂点、改进基于链码的目标面积计算方法计算锯齿和叶裂的面积。从锯齿和叶裂的面积和周长占整个叶片的面积和周长的比例以及叶片包含的锯齿和叶裂数三个方面对叶片进行描述。实验对3种共70张叶片提取特征,归纳特征阈值范围。实验结果表明新方法可以大大提高计算面积的精确度,并且这三个特征可以体现出不同种的植物叶片,可以作为新的特征值,为识别植物物种和分类提供帮助。 相似文献
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可调螺距螺旋桨叶根螺栓应力分析 总被引:5,自引:1,他引:4
针对可调螺距螺旋桨叶根螺栓头部与杆身圆角过渡区域应力集中的问题,根据弹性和弹塑性理论,利用MSCMarc分析叶根螺栓在预紧工况以及螺旋桨处于工作状态的应力分布情况.采用截面法和渗透接触法分别计算预紧力的加载.结果表明,螺旋桨处于工作状态下叶根螺栓头部与杆身圆角过渡区域产生较小的塑性变形,对叶根螺栓强度的影响较小;采用截面法和渗透接触法均能有效地模拟螺栓预紧过程. 相似文献
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基于CFD的集装箱船阻力性能优化 总被引:1,自引:0,他引:1
基于CFD方法实现船体型线的自动优化。应用船型参数化建模方法分析特征参数,提取设计变量,以兴波阻力最小为目标,分别采用Sobol算法和Tsearch算法实现船体型线的自动优化。将上述方法应用于5 100 TEU集装箱船的型线自动优化,运用Shipflow软件进行CFD数值计算。评估结果表明优化船型在弗劳德数Fr=0.26时总阻力减少3.62%,说明该方法可行。 相似文献
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钟成明 《CAD/CAM与制造业信息化》2002,(9):53-56
一、前言 “510”动叶片特点是变截面型面、型面内弧350mm处加厚、叶根与型面的过渡半径为25mm、加厚型面与内弧过渡半径为25、叶冠为圆柱冠、叶片汽道有效长度为510mm,毛坯总长710mm,是根据市场需要而研制的。用在20万D200RN1N2机组上低压缸第四级动叶片。它能否顺利试制成功将直接影响该机组能否顺利出机,同时对提高产品在市场上的竞争力有着至关重要的作用。 相似文献
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Chang-Hyun Park Jun-Hee Lee Jae-Hyuk Jeong Dong-Hoon Choi 《Structural and Multidisciplinary Optimization》2014,49(1):131-145
When a cleaning blade in a laser printer is excessively deformed, immoderate permanent set can result, leading to weaker nip pressure between the cleaning blade and OPC drum that worsens its cleaning performance and printing quality. In this study, the correlation of the permanent set with stress and strain was investigated through tensile tests with rubber test specimens. Based on the experimental results, the maximum von-Mises stress value was used to quantify the permanent set. A design optimization problem was formulated to minimize the maximum von-Mises stress while satisfying the design constraints for maintaining appropriate contact between the cleaning blade and the OPC drum. We employed metamodel-based design optimization using design of experiments, metamodeling and an optimization algorithm to circumvent the difficulty of structural analyses at some design points. Using the proposed design approach, the optimal maximum von-Mises stress was reduced by 40.2 % compared to the initial stress value while all the design constraints were satisfied. In order to verify the validity of our design optimization result, we manufactured the cleaning blades according to the optimum design solution and performed permanent set and printer tests. The test results clearly showed the validity of our design optimization result. 相似文献
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To establish a bridge between grinding tool parameters and loaded tooth fatigue life, an innovative data-driven root flank bending fatigue life forecasting and optimization via Top-Rem tool parameters was proposed for grinding spiral bevel gears. The recent machine settings modification is extended into grinding Top-Rem tool parameters modification in case that geometric accuracy and root bending fatigue life are integrated into a collaborative optimization. The proposed Top-Rem modification includes three key steps: (I) arc-shaped blade, (II) top part, and (III) top fillet part. Then, while root bending stress is determined by using finite element method (FEM)-based simulated loaded tooth contact analysis (SLTCA), data-driven fatigue life forecasting is developed by correlating with the multiaxial fatigue damage model based assessment. Moreover, data-driven bending fatigue life optimization model is established by using Top-Rem tool parameters modification, where the important constraints in target flank determination includes: (i) root overcutting, (ii) geometric accuracy, and, (iii) fatigue life. For high accuracy and efficiency, two different strategies are proposed: (i) the different parameters modification types; and, (ii) sensitivity analysis of grinding Top-Rem tool parameters. Finally, proposed method can verify that bending fatigue life can be significantly improved by modifying the key Top-Rem tool parameters in early stage of the whole life product development for spiral bevel gears. 相似文献
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在当前汽轮机的某些极限设计工况下,基于无限寿命的线弹性考核规范已经无法满足当前的工程设计要求,需要发展弹塑性强度计算方法以及有工程意义的强度评估准则,并在此基础上引入低周疲劳寿命考核方法对零部件寿命进行分析预测.对某汽轮机末级长叶片进行弹塑性有限元分析,提出将基于局部应力 应变法的低周疲劳分析理论与商用疲劳分析软件相结合的方法对叶片进行强度设计的方法和流程.结果表明:所提出的弹塑性分析以及疲劳寿命评估方法能很好地反映长叶片的实际强度,有助于进一步制定一套完善的适合工程应用的长叶片强度评估标准,从而提高叶片的设计水平. 相似文献
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叶片与轮盘之间的榫联结构存在接触和摩擦组合运动,在较高的热-机械载荷作用下容易发生微动磨损并导致疲劳破坏.本文采用有限元法对叶片-轮盘榫联结构进行接触分析,计算不同摩擦系数和不同转速情况下的叶片榫头和轮盘榫槽之间的接触压力、接触滑动距离.结果表明,摩擦系数增大,榫联结构接触面上的接触压力和滑动距离减小;转速增加,则接触压力和滑动距离增大. 相似文献
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Huaxia Li Hyunkyoo Cho Hiroyuki Sugiyama K. K. Choi Nicholas J. Gaul 《Structural and Multidisciplinary Optimization》2017,56(1):183-201
This study aims to develop an integrated computational framework for the reliability-based design optimization (RBDO) of wind turbine drivetrains to assure the target reliability under wind load and gear manufacturing uncertainties. Gears in wind turbine drivetrains are subjected to severe cyclic loading due to highly variable wind loads that are stochastic in nature. Thus, the failure rate of drivetrain systems is reported to be higher than the other wind turbine components, and improving drivetrain reliability is critically important in reducing downtime caused by gear failures. In the numerical procedure developed in this study, a wide spatiotemporal variability for wind loads is considered using 249 sets of wind data to evaluate probabilistic contact fatigue life in the sampling-based RBDO. To account for wind load uncertainty in evaluation of the tooth contact fatigue, multiple drivetrain dynamics simulations need to be run under various wind load scenarios in the RBDO process. For this reason, a numerical procedure based on the multivariable tabular contact search algorithm is applied to the modeling of wind turbine drivetrains to reduce the overall computational time while retaining the precise contact geometry required for considering the gear tooth profile optimization. An integrated computational framework for the wind turbine drivetrain RBDO is then developed by incorporating the wind load uncertainty, the rotor blade aerodynamics model, the drivetrain dynamics model, and the probabilistic contact fatigue failure model. It is demonstrated that the RBDO optimum for a 750 kW wind turbine drivetrain obtained using the procedure developed in this study can achieve the target 97.725% reliability (2 sigma quality level) with only a 1.4% increase in the total weight from the baseline design, which had a reliability of 8.3%. Furthermore, it is shown that the tooth profile optimization, tip relief introduced as a design variable, prevents a large increase of the face width that would result in a large increase in the weight (cost) of the drivetrain in order to satisfy the target reliability against the tooth contact fatigue failure. 相似文献
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To join a medium or thick plate weldment with a full penetration, a groove is usually prepared in the space between two sections of metal. Because weld metal needs to be deposited within the groove to form the joint, it is expected that different groove type will require different heat input, which may consequently have influence on welding residual stress and deformation. Generally, different groove corresponds to different bead layout, so it can be foreseen that the groove type has a significant effect on temperature history, shape and size of heat affected zone, and region of sensitization in certain alloys such as austenitic stainless steel. The influences of groove type on residual stress, angular distortion and width of sensitization region in a SUS304 butt-welded joint were investigated by means of numerical simulation and experiment. Based on ABAQUS code, a computational approach with considering thermo-mechanical coupling behaviors, moving heat source, strain hardening and annealing effect was developed to simulate temperature profile, stress field and deformation in multi-pass joint. Welding temperature cycles, residual stress distributions and deformations in V, K and X groove joints were calculated through using the proposed computational procedure. Meanwhile, experiments were carried out to obtain residual stress distributions and angular distortions. Through comparing the numerical results and the measured data, the effectiveness and accuracy of the developed computational approach were verified. The simulation results show that groove type has a significant influence on welding residual stress distribution, angular distortion and width of sensitization region. 相似文献
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Yu-Hsin Kuo Chih-Chun Cheng Yang-Shan Lin Cheng-Hung San 《Structural and Multidisciplinary Optimization》2018,57(1):183-195
A support structure design technique for additive manufacturing (AM) is proposed that minimizes the deformation while using the least amount of support material, minimizes the time required to add the supports, and designs supports that are easily removed. This study presents a repulsion index (RI), which satisfies the easy removal requirement and minimizes the number of artifacts left on the specimen surface, and a weighting function, which quantifies the cost incurred by the time taken to build the supports. A multi-objective topological optimization based on the simple isotropic material with penalization method, continuous approximation of material distribution, and method of moving asymptotes is formulated that includes the proposed RI and cost formulation. Numerical simulations demonstrate that rational support layouts can be determined with the proposed cost-based formulation in the topological optimization, allowing designers to find design solutions with a compromise between specimen surface profile error and support structure costs. 相似文献
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压气机叶片扭曲规律的多目标三维气动优化 总被引:2,自引:0,他引:2
为了提高轴流压气机的等熵效率和总压比,采用基于人工神经网络及遗传算法的叶轮机械叶片三维优化设计方法,开发了一种高性能的动叶片。优化目标是在流量不减小的情况下,尽可能的提高转子叶片的总压比和等熵效率。优化仿真结果显示,优化后所获得的扭曲叶片可以有效地改善叶根处的流动分离,流动分离区明显后移,损失显著降低,在整个工作范围,等熵效率提高了1.27%-7.08%,流量和总压比也都得到了大幅度的提高。结果表明,对亚音叶片进行扭曲规律优化效果很明显,优化方法是获得高性能转子叶片的有效途径。 相似文献