共查询到20条相似文献,搜索用时 171 毫秒
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《机械工程与自动化》2020,(2)
针对飞机蒙皮和筋板锤铆过程,采用有限元法建立其运动学模型,以气压(锤铆力)、单钉铆接时间(单钉冲锤次数)及铆钉头内端面到蒙皮间距离为输入量,以镦头尺寸和蒙皮与筋板间间隙为输出量,对不同参数下飞机蒙皮锤铆过程进行仿真分析,得到60组样本数据。为了得到最优的铆接工艺参数,设计了基于BP神经网络的适应度函数,采用PSO算法对铆接工艺参数进行优化。仿真及实验结果表明:所优化的工艺参数能实现较好的铆接质量。 相似文献
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为提高飞机连接装配工艺规划的自动化水平,在研究飞机连接装配工艺特点的基础上,基于多色集合理论,在统一的数学模型中同时构建了工艺规划模型和资源配置模型.采用多色集合理论构建了工艺规划围道矩阵和扩展多色图,提出了多色图到多色集合关系规则模型的映射机制,以此建立了工艺规划模型,并提出了工艺路径求解算法.在此基础上,采用多色集合理论中的体运算,建立了与工艺规划模型匹配的工艺资源模型.以飞机铆接装配工艺规划为例,对所提理论与方法进行了验证. 相似文献
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针对具有多个铆钉连接的铝板这一典型航空结构件,提出了ABAQUS中铆接等效建模方法,探讨了钻孔应力对铝板的变形影响。首先考虑钻孔引入的应力、铆接时铆钉自身膨胀力以及多个铆钉连接的相互耦合作用建立ABAQUS铆接等效模型,并仿真计算得出铝板压铆后的变形结果;然后进行了普通切削和线切割铝板的铆接实验;最后将实验结果与仿真结果对比,证明了钻孔应力对铆接变形的显著影响和仿真方法的有效性。 相似文献
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蔡泽胡耀光闻敬谦张立祥 《计算机集成制造系统》2023,(1):236-245
为提升自动导引车(AGV)在智能工厂复杂动态环境下的避障能力,使其能在全局路径引导下安全、高效地完成避障任务,提出一种基于深度强化学习的局部避障方法。首先,将避障问题表示为部分观测马尔可夫决策过程,详细描述了观测空间、动作空间、奖励函数和最优避障策略,通过设置不同的奖励实现以全局路径引导局部避障规划;然后,在此基础上,采用深度确定性策略梯度算法训练避障策略;最后,建立了仿真实验环境,并设计多种实验场景来验证所提方法的有效性。实验结果表明,所提方法可以应对复杂动态环境,减小避障时间与距离,提高运行效率。 相似文献
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训练器振幅过大会在训练过程中对人体造成直接伤害,也会降低器械自身的使用寿命,为将振动幅度控制在合理范围内,提出了一种核心力量训练器抑振参数集的知识表达及映射方法。利用达朗贝尔原理计算训练器连接轴间隙的偏心量求解出质心线速度矩阵,结合各连杆受力情况构建运动学模型。采用正弦-梯形函数根据动力模型规划振动抑制曲线,并将曲线中角速度参数化,利用离散角位置差值计算出映射参数。实验结果表明,所提方法能够在极短的时间内降低核心力量训练器振动,满足核心训练器抑振的基本需求,表达及映射结果真实有效具有一定的实际应用价值。 相似文献
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为了实现桥式起重机主梁快速轻量化设计,提出了基于径向基神经网络代理模型和ASA-MMFD算法的桥式起重机主梁轻量化设计方法。在最优超拉丁立方试验设计的基础上,利用径向基神经网络代理模型建立桥式起重机截面设计参数和最大应力、最大位移和质量之间的映射关系,引入"全局+局部"的组合策略,通过自适应模拟退火算法对代理模型进行全局寻优,采用修正可行方向法进行局部搜索。利用测试函数和NASA减速器对所提方法进行验证,结果表明:在相同精度范围内,与ASA-MMFD算法相比,所提方法在调用模型次数方面大幅度减少,提高了优化效率。在此基础上,将其运用在桥式起重机主梁轻量化设计中,从而验证所提方法的适用性。 相似文献
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对轿车轮毂轴承单元的铆装工艺进行了理论分析和试验研究。建立了铆装力理论计算模型与铆装工艺有限元分析模型,研究了铆头轨迹、倾角和停留时间等工艺参数对铆装质量的影响,得出采用圆周轨迹、铆头倾角6°和停留时间0.8s时铆装质量最好的结论。以DAC2F10轿车轮毂轴承单元为例,在课题组开发的铆合装配专用机床上进行了铆装试验,验证了铆装力理论模型和铆装工艺有限元模型的合理性,并进一步优化铆头倾角为5.5°。采用所优化的铆装工艺试制出了轮毂轴承单元样件,耐久性试验测试最高使用寿命近2×105km,表明得出的铆装优化工艺能大幅提高轮毂轴承单元的使用寿命和可靠性。 相似文献
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研究了摩擦铆接设备的不同主轴动力参数对AA2024-T351铆钉/PEI ULTEM-1000母材摩擦铆接工艺镦头形态的影响。铆钉旋转速度、铆钉铆入速度、下压距离和急停速度是铆接镦头主要工艺参数,研究结果表明:铆钉旋转速度越高,摩擦铆接连接区域热输入越多;铆钉铆入速度过小,会出现铆钉逐渐深入钻削的现象,影响热量在铆钉和母材接触区域的积聚,铆钉铆入速度过高,热量还未来得及产生,铆钉材料就被撞弯;下压距离和急停速度可以调控摩擦铆接工艺镦头连接紧固效果。 相似文献
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S. Hossein Cheraghi K. Krishnan Bijay Bajracharya 《The International Journal of Advanced Manufacturing Technology》2008,39(11-12):1144-1155
Sheet metal parts are widely used in the assembly of aircraft. The most common method of assembling sheet metal parts is through riveting. Failure of a rivet can have severe consequences in terms of loss of human lives and money. There are many parameters associated with a riveting process that directly affect the quality of rivets including squeeze force, rivet length, rivet diameter, and hole diameter tolerance. Incorrect selection or variations in these parameters could induce excessive residual stresses that result in stress concentration sites and initiate cracks, and also result in improper rivet head deformation leading to loose rivets. This paper presents a study of the effect of the aforementioned riveting parameters on the quality of a formed rivet using finite element simulation. The study was part of a larger project carried out for the local aircraft industry and hence, uses the inch system. The research is conducted on a 1/8″ (0.125″) diameter rivet and a 0.064″ thick aluminum sheet. The results indicate that under normal variations in the riveting process parameters, when using the recommended countersunk depth of 0.042″ for rivet hole, most rivets that are formed will not meet the quality requirements. This is primarily due to the existence of a gap between the formed rivet and the hole. Decreasing the countersunk depth to 0.032″ allows for a higher range of hole and rivet diameter tolerances, as well as an increase in the range of squeeze force that can be applied without violating the quality requirements. 相似文献
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Multi-filed coupling numerical simulation and experimental investigation in electromagnetic riveting
Xu Zhang Hai Ping Yu Chun Feng Li 《The International Journal of Advanced Manufacturing Technology》2014,73(9-12):1751-1763
In this work, electromagnetic riveting (EMR) of aluminum alloy rivet was investigated by numerical simulation and experiments. The numerical simulation was carried out by means of ANSYS and LS-DYNA software. The SPHB (Split Hopkinson Pressure Bar) test was performed for 2A10 aluminum alloy rivets, and Johnson-Cook material model was used to describe it. The sequential electromagnetic-thermal-mechanical coupling model was established to analyze magnetic pressures, adiabatic temperature rise, and deformation process. Experiments and microstructure observation were performed to verify the proposed model. The formation of adiabatic shear band and the effective strain distribution were simulated, and the maximum temperature rise was up to 252 °C. The dynamic recrystallization was observed by optical microscopy observation under a discharging voltage of 2.0 kV. The simulation result of rivet heading accorded with experiments. 相似文献
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建立有效、可靠的自冲铆工艺及力学性能预测模型是其工业应用推广过程中亟待解决的一个重要问题。选取AA5182、AA5052和AL1420三种铝合金薄板材料,基于Box-Behnken Design(BBD)响应面法开展了铝合金自冲铆连接试验研究。以板厚、板材硬度和铆钉硬度为三参数输入条件,以冲头行程、最大冲压力和失效载荷为输出响应值,建立影响因素与响应值之间的回归模型,探究多种输入参数对响应值的影响规律。试验结果表明:依据回归模型得到的工艺和强度理论预测值与试验值之间的误差在8%以内,建立的回归模型具有较高的工程应用可靠性。通过三维响应面和等高线分析表明,板厚和铆钉硬度的交互作用对最大冲压力和失效载荷的影响最大,冲头行程主要受板材硬度和铆钉硬度的交互影响。 相似文献
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Faisal Aman S. Hossein Cheraghi Krishna K. Krishnan Hamid Lankarani 《The International Journal of Advanced Manufacturing Technology》2013,67(1-4):545-562
Sheet metal parts are widely used in the assembly of aircraft. The most common method of joining sheet metal parts is through riveting. There are many parameters associated with a riveting process that affect the quality of rivets and the integrity of the final assembled product. This paper presents a study on the effect of some controllable process parameters in riveting (i.e., the sequence of riveting, distance between rivets (pitch), and gap between sheets) on the quality of riveted lap joints and the formed rivets. The study is performed on a one eight-inch nominal diameter flat head Tinner rivet and 0.064-in.-thick aluminum sheet. Finite element simulation is used as a means of modeling and analysis of the riveting process. Statistical design of experiment is employed to analyze the simulation data. A good combination of riveting process parameters is found which minimizes the residual stress in sheets and rivets, bulging and material growth in sheets, and which reduces the chances of postriveting clearance in a riveted lap joint. 相似文献