一个大挠度柱面弯曲板条的求解

本文应用付宝连的大挠度弯曲直梁的功的互等定理,求解一个柱面弯曲板条的挠曲面方程.     

复合铣削的金属件堆焊成形尺寸研究

针对目前金属件堆焊中存在的成形效果较差和尺寸精度较低等问题,建立了单道和多道焊缝的尺寸模型,并通过分析焊缝成形尺寸的关系,确定出最佳熔敷间距。同时,采用正交试验法分析了各个焊接参数对成形尺寸的影响程度,验证了模型的普适性。在实例分析中,采用自主设计的复合铣削加工系统,并改变多层多道焊缝的堆焊路径,从而实现对构件尺寸的有效控制,验证了该项工艺技术的可行性和有效性。     

Unequal-thickness billet optimization in transitional region during isothermal local loading forming of Ti-alloy rib-web component using response surface method

Avoiding the folding defect and improving the die filling capability in the transitional region are desired in isothermal local loading forming of a large-scale Ti-alloy rib-web component (LTRC). To achieve a high-precision LTRC, the folding evolution and die filling process in the transitional region were investigated by 3D finite element simulation and experiment using an equal-thickness billet (ETB). It is found that the initial volume distribution in the second-loading region can greatly affect the amount of material transferred into the first-loading region during the second-loading step, and thus lead to the folding defect. Besides, an improper initial volume distribution results in non-concurrent die filling in the cavities of ribs after the second-loading step, and then causes die underfilling. To this end, an unequal-thickness billet (UTB) was employed with the initial volume distribution optimized by the response surface method (RSM). For a certain eigenstructure, the critical value of the percentage of transferred material determined by the ETB was taken as a constraint condition for avoiding the folding defect in the UTB optimization process, and the die underfilling rate was considered as the optimization objective. Then, based on the RSM models of the percentage of transferred material and the die underfilling rate, non-folding parameter combinations and optimum die filling were achieved. Lastly, an optimized UTB was obtained and verified by the simulation and experiment.     

6061铝合金超薄壁弯管制造工艺及组织性能研究

通过单向拉伸试验建立了材料的本构方程,对6061铝合金板材半片拉深成形过程进行了有限元模拟,研究了摩擦系数与压边力对拉深成形结果的影响规律模拟结果表明:拉深成形时,应采用较大的压边力和较小的摩擦系数,以避免外管的外弧处易出现明显的起皱缺陷;基于模拟结果,进行了6061铝合金Φ202mm×1mm弯管半片拉深成形;最后对半片焊接后的超薄壁弯管进行了耐压爆破试验及关键部位微观组织分析.     

激光快速成形Inconel 718拉伸性能和ANSYS模拟分析研究

采用激光快速成形技术制成Inconel718材料，对其拉伸性能和微观组织进行分析。结果表明，其拉伸性能和微观组织均具有各向异性。采用ANSYS分析软件得出试样拉伸应力分布图，通过模拟数据与试验数据对比，两者应力-应变曲线得到很好吻合，为Inconel718材料复杂机械构件在研制阶段通过有限元分析提供设计依据。     

某型飞机电液压力伺服阀常见故障分析

作为防滑刹车系统中的重要组件之一,电液压力伺服阀对飞机防滑刹车系统的可靠性起着关键性作用,但通常其故障率较高.本文以某型飞机为背景详细论述了飞机防滑刹车系统中电液压力伺服阀的结构组成、工作原理、常见故障现象、原因及改进方法.     

A toolpath strategy for improving geometric accuracy in double-sided incremental sheet forming

The double-sided incremental forming (DSIF) improved the process flexibility compared to other incremental sheet forming (ISF) processes. Despite the flexible nature, it faces the challenge of low geometric precision like ISF variants. In this work, two strategies are used to overcome this. First, a novel method is employed to determine the optimal support tool location for improving geometric precision. In this method, the toolpath oriented the tools to each other systematically in the circumferential direction. Besides, it squeezed the sheet by the same amount at the point of interest. The impacts of various support tool positions in the circumferential direction are evaluated for geometric precision. The results demonstrate that the support tool should support the master tool within 10° to its local normal in the circumferential direction to improve the geometric accuracy. Second, a two-stage process reduced the geometric error of the part by incrementally accommodating the springback error by artificially increasing the step size for the second stage. With the optimal support tool position and two-stage DSIF, the geometric precision of the part has improved significantly. The proposed method is compared to the best DSIF toolpath strategies for geometric accuracy, surface roughness, forming time, and sheet thickness fluctuations using grey relational analysis (GRA). It outperforms the other toolpath strategies including single-stage DSIF, accumulative double-sided incremental forming (ADSIF), and two-stage mixed double sided incremental forming (MDSIF). Our approach can improve geometric precision in complex parts by successfully employing the support tool and managing the springback incrementally.     

ALE-9开阵天线辐射柱故障分析

针对单脉冲二次雷达所使用的ALE-9开阵天线,研究了辐射柱故障对雷达水平波束的影响。通过分析发现雷达天线各辐射柱的状态对天线水平波束的影响是不同的。通过大量的计算找出影响水平波束形状的关键柱体,从而在实际中加以重点监测和维护。     

人工神经网络在板料拉深成形中的应用研究

在反向传播网络的基础上提出了一个圆筒件拉深成形的辅助工艺设计方案,对BP网络在拉深工艺中的应用进行了尝试。结果表明:该方法与传统的设计方法相比,计算工作量较少,可靠性好。     

薄膜传动带拉制成形工艺研究

结合加工技术实践,对薄膜传动带的拉制原理、加工方法、试验和检测、制造和应用中出现的一些明显纵向弯曲、骤断、试验和使用时发生的脱带、断带现象,进行了简要介绍和初步讨论,解决小型精密机械的传动问题。