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平底无铆塑性连接铆接头的抗拉强度只能通过大量破坏性试验获得,且强度检测成本高、周期较长。重点分析铆接头在拉伸过程中的颈部断裂失效、拉脱失效及混合失效三种失效形式及成因;建立平底无铆塑性连接过程的数值模型,获得铆接头的剖面几何参数,通过铆接头的剖面观测试验验证数值模拟的精确性;借鉴管材拉拔过程中的主应力法,基于铆接头的剖面几何参数建立平底无铆塑性连接抗拉强度预测模型;进一步通过铆接头强度检测试验验证了抗拉强度预测模型的正确性,深入分析底厚值对抗拉强度的影响规律。结果表明,铆接头抗拉强度预测值与试验值最大误差为14.8%,其主要误差来源于铆接头加工硬化系数、摩擦因数、底厚值等参数;铆接头抗拉强度随着底厚值的减小呈递增趋势,当底厚值为0.50 mm时,Al5052-Al5052的抗拉强度最大,铆接头发生混合失效。建立一种高效、低成本的铆接头成形质量评价方式,对平底无铆塑性连接铆接头的几何参数优化具有指导意义。 相似文献
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为研究钢铝一体化结构车身无铆钉自冲铆接接头力学性能,引入反向传播神经网络模型来描述板材厚度、板材硬度和成形接头底部直径等工艺参数与接头剪切力及剥离力强度等力学性能的映射关系.由于标准反向传播网络存在训练精度低、收敛速度慢及泛化能力差等缺陷,采用归一化法与Levenberg-Marquardt算法相结合的算法来优化神经网络预测模型连接权值,提高了神经网络模型的预测精度和泛化能力.对神经网络的预测结果进行检验的结果表明,训练后的神经网络模型能够准确有效地预测无铆钉自冲铆接接头力学性能,证实了神经元网络应用于无铆钉自冲铆接接头力学性能预测的可行性与可靠性,为优质的钢与铝无铆钉自冲铆接接头的设计提供了依据. 相似文献
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由于具有传统点焊连接无法替代的优势,无铆钉自冲铆接技术在汽车、家电等行业中得到了较广泛的应用.铆接接头的质量及强度是人们关注的热点问题,而铆接工艺参数和模具结构参数是影响接头质量和强度的主要因素.通过对同种铝板件L5在不同的压边力及模具结构参数下的无铆钉自冲铆接的试验研究,分析这些参数对铆接接头的失效形式、断面质量和剪切强度的影响规律.研究结果表明:接头剪切时的主要失效形式是剪断;合理的铆接工艺参数及模具结构参数可以得到比较理想的接头断面质量及较高的接头剪切强度. 相似文献
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针对目前车用22MnB5高强钢和7075铝合金板料在连接工艺上存在的问题,提出一种高强钢和铝合金异种材料车身零件的热铆接冷模具淬火(Hot riveting quenching, HRQ)无铆钉铆接工艺,利用22MnB5在高温下良好的成形性及易淬性,实现对22MnB5高强钢与7075铝合金的有效连接。通过建立HRQ无铆钉铆接的成形和淬冷有限元模型,证明了该工艺的可行性,使铆接后接头的高强钢具有全马氏体组织,保证了接头的强度。并从仿真和试验两方面研究高强钢铆接温度对接头尺寸颈厚值Tn、自锁值Tu的影响,发现在600~800 ℃区间内,Tn和Tu均呈现先上升后下降的趋势,Tu受温度影响更显著,两者均在700 ℃时获得最大值,表明700 ℃是高强钢板料的最佳铆接初始温度。 相似文献
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气动锤铆是飞机铆接装配的主要方式之一,主要工艺参数包括铆枪气压、击打次数和顶紧力.通过搭建气动锤铆试验台,通过设计单因素试验和正交试验,研究气动锤铆工艺参数对镦头尺寸、干涉量大小及其均匀性的影响规律,提出一种通过改变铆枪顶紧力而改善铝锂合金板材内部的铆接干涉量及其均匀性的方法,为实际生产中提高气动锤铆质量提供参考和依据... 相似文献
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轻量化作为汽车节能减排的重要手段,得到世界各国的高度重视。目前车身大都采用多材料混用,而异质材料用传统电阻点焊难以形成可靠连接。无铆钉铆接技术是一种冷成形连接工艺,避免了接头热输入问题,通过材料的机械自锁作用形成有效接头。文章通过控制铆接行程,凸凹模直径等参数对不同材料匹配的铆接试样进行拉剪实验。结合成形过程中力-位移曲线,研究无铆钉铆接接头的力学性能及断裂机理。研究发现,拉剪过程中铆接试样出现三种断裂模式,即上层板铆钉压溃,界面断裂和下层板铆钉塑性变形。其中,发生下层板铆钉塑性变形断裂模式的试样表现出更高的拉剪强度和较好的吸能效果。对于界面断裂、上层板接头颈部发生开裂,接头拉剪强度取决于上层板侧壁厚度。 相似文献
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采用一种新的塑性成形连接方法--压印连接方法来实现铜、铝合金板的连接,通过拉剪实验研究了连接接头的力学性能,并分析了铜、铝合金板的排列顺序对接头拉剪载荷的影响。实验结果表明,对于铜、铝复合接头,铜板在上时接头具有较高的拉剪载荷(3kN),是铝板在上时拉剪载荷的4.6倍。根据接头失效形式对复合接头进行优化后发现:下层铝板的厚度增大时,接头的拉剪强度略有增大,拉剪过程中的能量吸收明显增大;提高下板材料强度时,接头的拉剪载荷明显增大;铜板作为上板进行压印连接时,失效形式为颈部断裂失效,且接头的拉剪强度较大。 相似文献
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压印连接是近年来新兴的连接方式,因其具有简单高效、低耗环保等优点,使得在应用连接方面越来越受到重视。疲劳破坏是机械构件失效的主要形式,疲劳过程中的微动磨损是造成零部件失效的主要原因之一。基于以上条件,对铝合金压印接头的疲劳性能进行了试验研究,结果显示疲劳失效部位主要集中在下板靠近压印点处,断口处发现大量微动磨屑,经能谱分析可以确定磨屑成分主要为氧化铝和金属铝;对疲劳失效断口和微动磨损区域进行了扫描电镜分析,发现压印接头的微动磨损部位主要分为两类,并对其进行了定义,一类定义为颈部微动磨损,另一类定义为环点板间微动磨损。分析发现颈部微动磨损所占比例随着外加载荷的大小而变化,且微动磨损是导致压印接头疲劳失效的重要因素。 相似文献
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Tong Wen Hui Wang Chen Yang Lan Tao Liu 《The International Journal of Advanced Manufacturing Technology》2014,71(9-12):1709-1715
The existence of relatively high protrusions above the sheets on most of the clinched joints could sometimes bring about an undesired result in the subsequent processing and, therefore, the application of the clinching technologies might be restricted. The current study proposed a countermeasure by imposing compression on the joints with a pair of contoured tools and then obtaining a controlled local plastic deformation of the joints, resulting in a reduction of the protrusion height. A typical two-layer clinching of 6063 aluminum alloy sheets with the thickness of 0.8 mm was employed to study the successional processes of clinching, reshaping, and separation. Geometrical parameters of the reshaping tools were optimized in terms of pull-out strength on the basis of numerical simulation and orthogonal design. It was found that diameter d of the truncated cone end on the reshaping die, inclination α of the truncated cone, and then fillets of the die and punch are of important influence on the connecting strength. Moreover, connecting strengths of the clinched joints before reshaping and after reshaped with the optimal parameters of the tools were compared experimentally. The results show that the protrusion height of the clinched joints can be reduced dramatically by the method without decreasing the connecting strength. In the example, the protrusion height of the clinched joint decreased from 1.7 to 0.68 mm, while the average pull-out strength of the joints increased from 230.8 to 331.4 N, and the shear strength increased from 559.7 to 657.5 N. 相似文献
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Recent development in finite element analysis of clinched joints 总被引:1,自引:1,他引:0
Xiaocong He 《The International Journal of Advanced Manufacturing Technology》2010,48(5-8):607-612
Clinching is a high-speed mechanical fastening technique for point joining of sheet materials. Published work relating to finite element analysis of clinched joints is reviewed in this paper, in terms of process, strength, and vibration characteristics of the clinched joints. It is concluded that the finite element analysis of clinched joints will help future applications of clinching by allowing system parameters to be selected to give as large a process window as possible for successful joint manufacture. This will allow many tests to be simulated that would currently take too long to perform or be prohibitively expensive in practice. 相似文献
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Yue Zhang Xiaocong He Yifeng Wang Yi Lu Fengshou Gu Andrew Ball 《The International Journal of Advanced Manufacturing Technology》2018,96(9-12):3057-3068
Mechanical clinching is a connection technology that is widely used in different industrial fields because it has several advantages, including easy preparation, an excellent fatigue property and environmental friendliness. In this study, tensile-shear tests and fatigue tests were conducted to characterize the mechanical properties of clinched joints using aluminium alloys. The experimental results showed that the fracture regions were concentrated in the indentations of the lower sheets. The failed surfaces were examined using a scanning electron microscope and an energy-dispersive X-ray machine to study the fretting fatigue failure mechanisms of the clinched joints. Two types of fretting wear modes were observed: the neck fretting wear mode and indentation-surrounding fretting wear mode. The results also showed that the proportions of these two fretting wear modes could be impacted by the applied load levels. 相似文献
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采用AA5052铝合金挤压管作内层基管、Q235碳素结构钢卷焊管作外层覆管的钢铝复合管对复合管颗粒介质胀形行为进行研究。通过塑性理论分析胀形过程中管间切向摩擦力及法向压力对基管应力大小的影响;利用数值模拟分析管间摩擦因数和覆管各向异性对基管的应变成形极限的综合影响,并给出单管、复合管胀形时的壁厚减薄情况和基管的应力、应变分布;通过管材颗粒介质内高压胀形试验,对比单管和复合管胀形条件下铝合金管的极限胀形比,分析复合管的变形协调性。结果表明:通过施加Q235碳素结构钢覆管,减小了AA5052基管胀形区中间截面处的双向拉应力,基管胀形区壁厚减薄变小,胀形比提高了22%,复合管下基管最大减薄率为17.5 %,成形性能显著提高。 相似文献