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为了准确预测工程机械上SUS304不锈钢点焊接头的疲劳寿命,提出了一种用于焊点寿命预测的S-N曲线。根据常见的几种点焊接头的结构形式,制备了不同板厚组合的拉剪疲劳试件,通过疲劳试验获取了试件的疲劳寿命数据。利用CT扫描实验获取了准确的焊核直径,建立了试件的有限元模型,并通过光学应变测量试验验证了该模型的准确性。然后,基于Rupp等效结构应力法和疲劳试验数据建立了综合不同板厚组合和载荷比的结构应力-寿命曲线(S-N曲线),并使用Goodman修正法消除了载荷比的影响。最后,建立了振动输送机有限元模型,并进行瞬态动力学分析获取了振槽焊点的结构应力,基于建立的S-N曲线预测了焊点寿命。结果显示,振槽各焊点接头无疲劳问题,存在焊点冗余情况,可以做轻量化设计。 相似文献
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变压器油箱箱体遍布焊缝,在振动工况下,油箱疲劳破坏常发生于角焊缝内部缺陷位置处。为分析角焊缝缺陷对变压器油箱疲劳寿命影响,建立了变压器油箱箱体有限元模型,根据油箱振动测试数据在nCode软件中对油箱整箱侧壁角焊缝进行疲劳分析,得到无缺陷情况下变压器油箱整箱侧壁角焊缝的疲劳寿命。取整箱侧壁角焊缝疲劳最危险角焊缝,进一步建立局部含缺陷角焊缝模型,分析含气孔、夹渣缺陷时变压器油箱角焊缝的疲劳寿命的影响规律。最终发现:对于夹渣缺陷,夹渣弹性模量与焊缝弹性模量相差越大,越容易造成疲劳破坏,且软夹渣较硬夹渣更为危险;气孔缺陷尺寸的增大会造成疲劳寿命的减少,而气孔位置越靠近焊根,疲劳寿命越小;且气孔缺陷较夹渣缺陷更容易造成疲劳破坏。 相似文献
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提出了一种基于超声回波的焊点缺陷疲劳寿命预测评价方法。该方法采用模糊数学理论,基于超声回波特征获得损伤系数,然后综合考虑法向应力、剪切应力和初始缺陷的影响,将焊点缺陷在裂纹扩展路径上的修正平均等效应力强度因子作为疲劳评价的参量。通过对DP600GI材料的合格焊点、焊核过小焊点和烧穿焊点的接头进行疲劳试验,比较不同缺陷对焊接疲劳寿命的影响,得到一条修正平均等效应力强度因子与疲劳寿命的拟合曲线作为含初始缺陷的焊点疲劳寿命预测曲线,研究结果表明,该曲线能有效预测含初始缺陷的点焊接头的疲劳寿命。该方法有助于合理设计电阻点焊的缺陷容限。 相似文献
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对7075/2A12异种铝合金搅拌摩擦焊搭接接头进行了疲劳加载测试,并观察了疲劳断口特征。根据实际试件结构建立局部应力应变法和缺口应力法有限元模型,对焊缝区域进行应力应变分析;结合Soderberg修正方程对Manson-Coffin(MC)模型中应力部分进行修正,再根据有限元分析结果,使用局部应力应变法和缺口应力法对异种铝合金搅拌摩擦焊搭接接头进行疲劳寿命预测。试验结果表明,有效搭接厚度严重影响试件的疲劳寿命;位于受载7075前进侧的钩状缺陷比7075后退侧钩状缺陷对疲劳寿命的影响大。与试验结果相比,局部应力应变法中,2组试件最小板厚处疲劳寿命的预测结果都要比钩状缺陷根部处疲劳寿命的预测精度高。部分试件结合Soderberg方程修正的MC模型预测误差大部分都在2个因子之内,而Smith-Watson-Topper(SWT)模型和其他MC修正模型预测结果均在3个因子之内,Sachs修正的MC模型和Morrow修正的MC模型的预测结果相近;缺口应力法中,部分试件预测结果较好,误差在2个因子之内。 相似文献
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将蒙特卡罗法和有限元方法用于分析球珊阵列封装(BGA封装)焊点中微孔洞缺陷对焊点应力的影响。先用X射线断层扫描方法测定焊点中孔洞大小及其分布规律,然后利用Abaqus有限元分析软件建立BGA封装有限元模型,采用Anand本构方程描述焊点的应力应变响应,分析BGA封装焊点应力分布情况;并针对关键焊点即应力最大的焊点,建立了含孔洞大小和位置呈随机分布的焊点参数化有限元模型,结合试验结果,分析了孔洞直径和位置对焊点应力分布的影响。结果表明:微孔洞直径越小,越接近于焊点的表面,焊点中的应力越大。 相似文献
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基于蠕变模型细间距器件焊点疲劳寿命预测 总被引:3,自引:0,他引:3
基于Garofalo-Arrheninus模型,采用有限元软件Marc模拟焊点温度场、应力—应变场和变形情况,借助修正C-M方程计算焊点的疲劳寿命。研究结果发现,器件相应材料中,只有印刷电路板内部温度场分布不均匀,这是材料热传导系数过小所导致的。发现应力集中的区域出现在焊根、焊趾以及引线和焊点交界处,基于Marc软件和基于Ansys软件模拟的结果一致,并和实际情况良好吻合。时间历程蠕变和塑性应变出现明显的累积迭加的趋势,两者共同作用导致焊点破坏,致使器件失效。在温度循环加载的过程中,整个器件一直处于拉应力的状态。基于修正C-M方程计算出焊点的疲劳寿命为665.7周次,和试验结果基本吻合。 相似文献
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选取焊点高度、焊盘直径、引脚间距、焊点矩阵四个形态结构参数作为关键因素,采用水平正交表L18(37)设计18种不同形态结构参数组合的塑料封装球栅阵列(plasticballgridarray,PBGA)器件无铅焊点,建立18种PBGA无铅焊点的三维有限元分析模型,并进行随机振动条件下的应力应变有限元分析,得到18种不同形态结构参数的PBGA无铅焊点的应力应变数据,针对应力应变数据进行极差分析与方差分析。结果表明,随机振动条件下四个因素对PBGA无铅焊点应力应变的影响由大到小依次是焊点矩阵、引脚间距、焊点高度和焊盘直径,应力应变最小的焊点最佳形态结构参数水平组合为焊点高度0.32mm、焊盘直径0.30mm、引脚间距0.65mm和焊点矩阵6×6;在置信度为95%的情况下,引脚间距和焊点矩阵对PBGA无铅焊点随机振动应变具有显著影响,焊盘高度和焊盘直径对应变影响不显著。 相似文献
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BGA结构无铅微焊点的低周疲劳行为研究 总被引:2,自引:0,他引:2
基于塑性应变能密度概念提出微焊点低周疲劳裂纹萌生、扩展和寿命预测模型,阐明其与连续介质损伤力学的联系,评估应力三轴度对预测模型的影响,并通过试验和数值计算相结合的方法确定出微米尺度球栅阵列(Ball grid array,BGA)结构单颗Sn3.0Ag0.5Cu无铅焊点(高度为500~100 μm,焊盘直径为480 μm)疲劳裂纹萌生和扩展模型中的相关常数。研究结果表明,疲劳裂纹萌生和扩展循环数与每个循环所产生的塑性应变能密度均呈幂函数关系;应力三轴度会影响疲劳裂纹扩展速率,并最终影响焊点的疲劳寿命;应力三轴度与加载方式有关,拉伸载荷下焊点的应力应变行为受异种材料界面和封装结构力学约束作用的影响,应力三轴度随焊点高度降低而明显升高;而剪切载荷作用下焊点中的力学约束十分有限,焊点高度变化对应力三轴度的影响非常小;测得的高度为100 μm焊点的疲劳裂纹扩展相关常数可以很好地用于预测其他不同高度焊点的疲劳寿命,表明所提出的预测模型可以有效地减小由几何结构和体积变化造成的塑性应变能集中现象对焊点疲劳寿命的影响。 相似文献
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Qiang Guo Mei Zhao 《The International Journal of Advanced Manufacturing Technology》2005,26(7-8):887-895
The objective is to find whether fatigue of the solder joint or the location of the chip is related to the curvature and torsional
curvature when SMT solder joints are under vibration or shock condition. However, the torsional curvature is always omitted.
In this paper the relationship of curvature and torsional curvature is argued, and it is found that the quantity of the curvature
is closer to that of the torsional curvature and shows that omitting the torsional curvature is not accurate. Also, the fatigue
of the solder joint including torsional curvature is obtained. One kind of SMT printed circuit board (PCB) used in aviation
and spaceflight has been obtained to test its modes. According to the modal results, the location of the SMT assembly is not
very suitable and the reliability of SMT solder joints will decrease, which will make an unreasonable catastrophe appear.
Meanwhile, the location optimization including curvature and torsional curvature is considered and four areas are obtained
in the PCB to locate the chip for increasing the fatigue of solder joints. In this paper the results obtained by assuming
the PCB is simply supported in its four boundary. The other fixed condition will be calculated using a similar method. 相似文献
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选取焊盘长度、焊盘宽度、钢网厚度和间隙高度为四个关键因素,采用水平正交表L25(56)设计25种不同参数水平组合的底部引线塑料封装(bottom leaded plastic,BLP)器件焊点,建立25种焊点的形态预测模型和有限元分析模型;对热循环加载条件下BLP焊点进行非线性有限元分析,计算25种不同焊点形态的BLP焊点热疲劳寿命;基于热疲劳寿命计算结果进行极差分析.结果表明,四个因素对BLP焊点热疲劳寿命影响由大到小的顺序依次是焊盘宽度、焊盘长度、间隙高度和钢网厚度;可靠性最高的BLP焊点工艺参数水平组合为焊盘长度1.1 mm、焊盘宽度0.65 mm、钢网厚度0.15 mm和间隙高度0.09 mm. 相似文献
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电子电路中焊点的热疲劳裂纹扩展规律 总被引:4,自引:1,他引:3
采用试验方法研究表面贴装结构焊点在热疲劳过程中的疲劳裂纹扩展规律。试验研究中选用两种不同尺寸的焊盘及两种不同的钎料(包括传统的锡铅钎料和锡银铜无铅钎料SAC305),通过观测焊点截面上的裂纹萌生及扩展过程来研究焊点中的热疲劳裂纹扩展规律。研究结果表明,在热疲劳过程中,焊点经历热疲劳裂纹萌生和扩展的两个不同阶段,其中裂纹萌生所占的时间比例较小。在热疲劳后期,裂纹贯穿整个焊点从而造成焊点结构失效。研究发现,焊点结构失效过程中存在着两种不同的裂纹扩展模式,并且锡铅钎料焊点和SAC305无铅钎料焊点的裂纹扩展规律表现出明显的差异。另外研究还发现,当焊盘尺寸较小时,焊点的抗热疲劳性能相对较差;SAC305无铅钎料焊点的抗热疲劳性能优于传统锡铅钎料焊点。 相似文献
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This paper predicts the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory devices due to harmonic excitation through experiments and finite element analysis. Finite element models of the memory device with simplified solder joints and with detailed solder joints were developed as a global model and a local model, respectively. A global-local modeling technique was used in the finite element simulation to calculate the stress magnitude of solder joints in the memory device under vibration. Stress versus life (S-N) curve was generated for the memory devices under various vibration levels to derive the fatigue constants of solder material. The fatigue life of the memory device was then determined by using the Basquin equation and Miner’s rule. It was experimentally verified that the predicted fatigue life of the memory device under cumulative damage conditions matches the experimental results within reasonable accuracy. 相似文献
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R.S. Chen S.C. Tseng C.S. Wan 《The International Journal of Advanced Manufacturing Technology》2006,27(7-8):677-687
Among the PBGA (plastic ball grid array) packages, a 72-I/O OMPAC (overmolded effect array carrier) package is studied during
thermal cycling. The ANSYS software is applied to analyze the effects of some factors on the solder joint for the fatigue
life due to elastoplastic deformation of the electronic package; those factors are solder structure, shape, and pitch. The
result shows that the maximum equivalent plastic strain range occurs at two interfaces, one is between the solder joint and
the substrate, another one is between the solder joint and the printed circuit board. Moreover, the solder shape is determined
by the solder height and the pad diameter under a fixed value of solder volume. It is found that the convex-shaped solder
with larger height and smaller pitch has smaller maximum equivalent plastic strain range, which leads to the longer fatigue
life. In addition, there are two kinds of solder structure: pure solder joint and copper core solder joint. In the copper
core solder joint, the eutectic part becomes so small that a larger strain is induced. Therefore, the pure solder joint has
smaller maximum equivalent plastic strain range and longer fatigue life than the copper core solder joint. 相似文献
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Hadi Taghizadeh Tajbakhsh Navid Chakherlou Afshin Babaei Aghdam 《Journal of Mechanical Science and Technology》2013,27(5):1415-1425
To predict fatigue crack initiation and fatigue crack growth lives in cold expanded double shear lap joints a numerical method has been employed. The total estimated fatigue lives were compared with available experimental fatigue test results for plain hole and cold expanded hole specimens of Al 2024-T3 in double shear lap joints. Three-dimensional finite element simulations have been performed in order to obtain the created residual stresses field due to cold expansion and subsequent far field longitudinal loading in the double shear lap joint. The obtained stress and strain distributions from the finite element analyses were employed to predict stress concentration factors to calculate fatigue crack initiation and fatigue crack growth lives using AFGROW computer code. The predicted fatigue lives demonstrate that there is a good agreement between the proposed method and experimental fatigue test results. 相似文献
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基于跌落试验与有限元模拟结果进行球栅阵列(ball grid array,BGA)无铅焊点的跌落碰撞寿命分析。首先用统计学的方法,建立跌落碰撞下不同脉冲幅值与脉冲时间的BGA封装无铅焊点寿命预测模型,并通过其寿命预测模型定量评估BGA无铅焊点的跌落碰撞寿命;接着用Power原理建立一个将焊点最大拉应力与焊点失效时跌落次数联系起来的焊点寿命预测模型。无铅焊点寿命预测模型的研究对封装的设计及其可靠性提高具有一定的指导意义。 相似文献