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排序方式: 共有138条查询结果,搜索用时 15 毫秒
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Xingying ZHOU Henan LIU Tianyu YU Ruiyang GUO Guangzhou WANG Yazhou SUN Mingjun CHEN 《中国航空学报》2023,36(7):194-212
High-precision turning(HPT) is a main processing method for manufacturing rotary high-precision components, especially for metallic parts. However, the generated vibration between tool tip and workpiece during turning may seriously deteriorate the surface integrity. Therefore,exploring the effect of vibration on turning surface morphology and quality of copper parts using3D surface topography regeneration model is crucial for predicting HPT performance. This developed model can update the machin... 相似文献
133.
为了揭示上浮过程中的尾流涡结构及其与气泡之间的相互作用,分别采用阴影图像法和层析PIV技术,对单个气泡在静止水中自由Z字型上浮的过程进行了实验研究,得到气泡的形状、运动和三维的尾流速度场。采用"λ" _"ci" 涡判据和有限时间李雅普诺夫指数(Finite-Time Lyapunov Exponent,FTLE),从速度场识别出三维的尾流涡结构和二维的拉格朗日拟序结构。结果表明,Z字型上浮过程中,气泡周围环绕有涡环,涡环会沿运动路径脱落交替的、方向相反的发卡涡;单个发卡涡脱落过程中,涡环一侧的FTLE脊线会闭合形成拉格朗日涡。由此可得到结论,发卡涡的周期性脱落,使涡环相对于气泡的对称性被周期性交替破坏,导致气泡形成Z字型周期运动;单个发卡涡脱落过程中,涡环两侧各自对发卡涡的流体输运存在显著差异。 相似文献
134.
This paper deals with the problem of intercepting maneuvering targets with terminal angle constraints for missiles subjected to three-dimensional non-decoupling engagement geometry.To achieve the finite-time interception and satisfactory overload characteristics, a time varying sliding mode control methodology is developed based on a time base generator function. The main feature of the proposed guidance law guarantees the Line-of-Sight(LOS) angles to converge to small neighborhoods of the desir... 相似文献
135.
使用PCD立式铣刀对聚合物浸渍裂解法(PIP)制备的SiC_(f)/SiC复合材料开展单因素铣削试验,通过对加工中产生的切削力和加工后的表面粗糙度进行测量,分析了铣削工艺参数对其的影响;对加工表面、纤维断口进行SEM分析,讨论了SiC_(f)/SiC复合材料加工表面的形成。研究结果表明,表面粗糙度与切削力的变化趋势相同,高主轴转速和小切削宽度有利于得到表面粗糙度较小的加工表面;近孔洞区域与远离孔洞区域的材料去除方式不同;材料中纤维发生面内偏移和层间屈曲,纤维存在多种去除方式。 相似文献
136.
《中国航空学报》2023,36(1):266-289
Highly accurate closed-form eigensolutions for flutter of three-dimensional (3D) panel with arbitrary combinations of simply supported (S), glide (G), clamped (C) and free (F) boundary conditions (BCs), such as cantilever panels, are achieved according to the linear thin plate theory and the first-order piston theory as well as the complex modal analysis, and all solutions are in a simple and explicit form. The iterative Separation-of-Variable (iSOV) method proposed by the present authors is employed to obtain the highly accurate eigensolutions. The flutter mechanism is studied with the benefit of eigenvalue properties from mathematical senses. The effects of boundary conditions, chord-thickness ratios, aerodynamic damping, aspect ratios and in-plane loads on flutter properties are examined. The results are compared with those of Kantorovich method and Galerkin method, and also coincide well with analytical solutions in literature, verifying the accuracy of the present closed-form results. It is revealed that, (A) the flutter characteristics are dominated by the cross section properties of panels in the direction of stream flow; (B) two types of flutter, called coupled-mode flutter and zero-frequency flutter which includes zero-frequency single-mode flutter and buckling, are observed; (C) boundary conditions and in-plane loads can affect both flutter boundary and flutter type; (D) the flutter behavior of 3D panel is similar to that of the two-dimensional (2D) panel if the aspect ratio is up to a certain value; (E) four to six modes should be used in the Galerkin method for accurate eigensolutions, and the results converge to that of Kantorovich method which uses the same mode functions in the direction perpendicular to the stream flow. The present analysis method can be used as a reference for other stability issues characterized by complex eigenvalues, and the highly closed-form solutions are useful in parameter designs and can also be taken as benchmarks for the validation of numerical methods. 相似文献
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