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基于不同应力比下激光喷丸强化6061-T6铝合金的疲劳裂纹扩展性能研究 总被引:6,自引:1,他引:5
为了研究不同应力比下激光喷丸强化(LSP)对6061-T6铝合金疲劳裂纹扩展性能的影响,采用有限元软件ABAQUS和疲劳分析软件MSC.Fatigue相结合,对应力比为0.1、0.3、0.5条件下的6061-T6铝合金紧凑拉伸(CT)试样进行了激光喷丸强化疲劳裂纹扩展的数值模拟,分析残余压应力对高低应力比下的裂纹闭合效应,探索不同应力比对激光喷丸强化疲劳寿命增益的影响。结果表明,经过激光喷丸后,3种不同应力比下的疲劳裂纹扩展速率较未处理试件都有一定的降低;应力比的取值对激光喷丸后CT试样的疲劳寿命有显著影响,应力比越小,激光喷丸对CT试样疲劳寿命的增益影响越明显。 相似文献
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用激光快速成形(LRF)技术制备304不锈钢拉伸试样,并对试样进行拉伸。利用光学显微镜观察了试样表面显微组织;利用扫描电镜(SEM)观察了试样断口的形貌特征,并用能谱仪(EDS)分析了取样点处的化学成分。结果表明,所制备试样显微组织晶粒细小,具有定向凝固的特征,在成形件内部存在微细观孔洞与裂纹。在拉伸断裂试样中,断口呈现韧性断裂的特征,断口部分区间氧、硅含量较高,形成金属化合物夹杂,使材料的力学性能变差。 相似文献
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1420Al-Li合金以其高比强度,高比刚度以及优良的低温性能,良好的耐腐蚀性和成型性而成为航空航天理想的轻质结构材料。本文对1420Al-Li合金进行了准原位拉伸试验,利用场发射扫描电子显微镜上安装的背散射电子衍射仪(EBSD-Channel5)对试样进行取向分析。EBSD结果表明:拉伸之前,1420Al-Li合金试样中存在弱织构{001}<100>;拉伸之后,弱织构消失,试样拉伸区存在近似于{001}<100>的{018}<018>织构。拉伸过程中晶粒绕晶带轴[001]和[010]发生转动,引起合金试样拉伸前后织构的变化。 相似文献
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为探明激光沉积制造TC4合金拉伸性能各向异性产生的机制,对不同取样角度的试样进行拉伸性能测试,并采用电子背散射衍射技术对成形件的晶体取向进行分析。结果表明:90°试样(拉伸试样的长轴方向与水平方向夹角为90°)的延伸率比45°试样高32%,抗拉强度和屈服强度分别低9%和8%;90°试样中的主要织构所对应的Schmid因子值最高,为0.485,外加拉伸应力σ与滑移方向分切应力τ之间的夹角θ为38°,试样首先开动的滑移系为柱面滑移系;45°试样的Schmid因子值最低,为0.415,θ为28°,试样首先开动的滑移系是锥面滑移系;90°试样中小角度晶界的占比最小,为1%,45°试样中小角度晶界的占比最高,为29.2%;90°试样具有最优的塑性,而45°试样具有最高的强度。 相似文献
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为了改善1Cr5Mo耐热钢焊接接头拉伸力学性能,利用CO2激光对其进行了表面改性处理,通过拉伸试验考察了激光热处理对拉伸性能的影响.利用扫描电镜观察了焊接接头的断裂形式和断口形貌,并用能谱仪分析了激光热处理前后试样表面化学元素的组成,讨论了残余应力和残余奥氏体对拉伸性能的影响.结果表明,激光热处理前后试样的拉伸断口均为韧性断裂,激光热处理后断裂性能有所提高;激光热处理试样表面产生晶粒细化和残余压应力的强化层,其屈服强度和抗拉强度分别提高了3.4%和13.7%,拉伸性能得到进一步提高;激光热处理试样的残余奥氏体含量有所降低,导致焊接接头的断面收缩率下降了18.61%,而延伸率基本不变,其均匀变形能力有所增强. 相似文献
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数字散斑相关法在高速变形测量中的应用 总被引:9,自引:4,他引:5
在SHTB加载装置上利用数字化的高速摄影和采集系统,并结合数字散斑相关方法,发展了一种光学动态变形测试技术,在霍普金森(Hopkinson)加载装置上实现了具有较高精度和分辨率的位移和变形场的实时光学测量.实验中,利用Imacon-790高速摄影机以105幅/s的速度分别拍摄了两组LY12试件的动态拉伸情况(一维平板拉伸试样和含对称缺口的拉伸试样),然后运用数字散斑相关方法对其不同时刻的图像进行分析和处理,可以得到试样在各个时间点的位移场.最后利用有限元数值模拟技术与实验结果进行了比较,验证了整个系统以及数字散斑相关方法用于高速动态测量中的可行性. 相似文献
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The paper provides a compact but accurate electro-thermal model of a long wiring on-chip interconnect embedded in the complex layout of a ULSI digital circuit. The proposed technique takes into account both the effect of temperature gradients over the chip substrate and the interconnect self-heating due to current flow. The proposed compact model is well suited to be interfaced with commercially available CAD tools employed for interconnect parasitic extraction and signal integrity verification. The paper also investigates the electro-thermal effects that arise in a long wiring on-chip interconnect in which current flow is dominated by displacement currents and thus is not uniform along the line. 相似文献
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Quan Chen Lei Yang Xianfeng Liu Jianming Guo Shuai Wu Xiaoqian Chen 《International Journal of Satellite Communications and Networking》2021,39(1):47-64
Multiple gateways are required in large satellite constellation networks (LSCNs) with inter‐satellite links (ISLs), and their placement may greatly affect the system performance. Gateway placement can be optimized to achieve better network performance under the non‐uniform ground demand distribution. This paper formulates a gateway placement optimization model for LSCN with ISLs, aiming at achieving an optimal overall performance including delay, traffic peak, and load balance. The constraints of potential gateway location, gateway‐satellite connectivity, and max hop‐count are considered. A genetic algorithm (GA)‐based method is proposed to solve the integer optimization problem with the help of quasi‐evenly distributed reference layout. A Starlink‐like constellation with ISLs is adopted in the simulation. The simulation results show that the optimized layout has better performance than the reference layout. Additionally, the locations with high user demand or at the middle of ocean are preferred by gateways. The network performance is jointly influenced by gateway placement, demand distribution, constellation configuration, node, and link capacities. The abnormally high ISL hop‐count is found in the south Indian Ocean, which is caused by constellation and ISL configuration. 相似文献
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应用激光跟踪仪进行机器人位姿测量时,为了减小激光跟踪仪分布位置对测量结果的影响,对激光跟踪仪布局位置开展优化。以ABB IRB1410型机器人为研究对象,规划了其测量区域。通过构建激光跟踪仪误差传递函数,对激光跟踪仪测距误差、测角误差对整体坐标测量精度影响进行分析。通过仿真分析研究了激光跟踪仪不同分布位置下机器人测量区域内测量点整体偏差的分布规律。通过构建激光跟踪仪布局评价函数并基于MATLAB无约束线性优化算法确定了激光跟踪仪最优布局位置主要位于测量区域中心轴线及其延长线附近,并对最优位置相邻区域整体测量偏差的分布规律进行了分析,为机器人现场测量提供一定的参考依据。 相似文献
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When optical fiber is deployed in practical engineering, bending and stretching of fiber optics is inevitable, which will affect optical communication. The fiber losses of different bending radii are simulated by COMSOL software. In order to verify the accuracy of simulation results, an experiment was designed to measure the losses of single-mode fiber under different bending radii and tension forces. The results show that the sensitive bending diameter of fiber loss is between 5 mm and 10 mm. The tensile effect has little influence on the fiber loss, but when the tensile force is greater than 160 N, the fiber breaks. This study provides an important reference for fiber layout in practical engineering. 相似文献
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通过对不规则物体布局特点的分析,依据遗传算法的基本思想,提出一种基于遗传算法的不规则物体布局求解算法.本算法选择合适的编码方法、遗传算子和合适的适应性度函数,仿真实验表明,该算法具有收敛速度快,解决早熟现象,能够在较短时间内获得较佳的布局方案. 相似文献
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介绍了模拟集成电路模块版图的开发系统.系统用高效的过程化版图描述语言构造模拟模块,编译产生与工艺及应用无关的模块版图生成器.系统的网络识别和模块内布线功能自动完成模块网络的完全连通,基于优选的电气特性驱动版图生成,提高设计可靠性.该系统已辅助设计出多个高性能集成运算放大器、模拟开关等芯片版图. 相似文献
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A new approach to select anoptimal set of test points is proposed. The described method uses fault-wise table and multi-objective genetic algorithm to find the optimal set of test points. First, the fault-wise table is constructed whose entries are measurements associated with faults and test points. The selection of optimal test points is transformed to the selection of the columns that isolate the rows of the table. Then, four objectives are described according to practical test requirements. The multi-objective genetic algorithm is explained. Finally, the presented approach is illustrated by a practical example. The results indicate that the proposed method can efficiently and accurately find the optimal set of test points and is practical for large scale systems. 相似文献