热超声倒装键合环状界面的形成

采用压力约束模式夹持倒装芯片,实现了热超声倒装键合,观察到环状的键合界面微观形貌,脊状撕裂棱以及表皮层碎片.采用有限元方法计算了键合界面应力、应力场的大小和分布在热超声倒装键合过程中的变化,从应力的角度揭示了环状界面的形成机理.研究结果表明,应力分布显示接触面边沿较其它位置更有利于去除表皮层、更有利于原子扩散形成键合强度,是形成环状界面的重要原因;振动的加载过程改变了应力和应力场的分布,使得应力分布进一步集中在振动位移决定的键合界面边沿位置,促进了环状界面的形成.     

连续铸轧流变行为的物理模拟及其应力-应变关系的演变

在Gleeble-1500热/力机上用专制的夹具系统对铝合金铸轧过程流变行为及其影响因素进行了系列的模拟实验研究,得到了不同变形条件下铝合金瞬态凝固连续固态流变成形过程中的形变规律.实验表明铝合金的[液-糊状-固]流变过程存在4个不同特征阶段,通过对实验数据进行多元线性回归分析,建立了适用于连续铸轧这一特定工况条件下铝合金流变本构方程.     

Modeling for driving systems of four-high rolling mill

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2519厚板搅拌摩擦焊缝组织性能及断裂分析

采用搅拌摩擦焊方法对厚度为20mm的2519高强铝合金板进行了单道对接焊试验,并对焊缝的微观组织、力学性能及断裂特性进行了分析.试验结果表明,在旋转速度为1600 r/min、焊接速度为30mm/min时,20mm厚板焊缝的抗拉强度可达313MPa;厚板焊接时,因焊接速度较慢,厚板焊缝搅拌区的平均显微硬度在115 HV左右,出现了较大程度的软化,其软化区长度约为55 mm;其断裂形式为韧性和脆性的混合型断裂.20mm厚板焊接时,上下板面搅拌区的温差在150℃左右,热机作用梯度沿板厚急剧变化,是厚板焊接比薄板焊接困难的原因之一.     

铸轧板形的影响因素及控制策略

本文阐述了铸轧板形的力学本质 ,并推导出板形的计量公式。结合大量试验观察 ,基于“广义原始辊缝”概念 ,运用体积不变原理及 P-H图对铸轧环境下板形的影响因素进行了分析 ,提出铸轧板形主要与金属的布流状态有关 ,针对板形缺陷的不同模式提出了相应控制策略。     

Global coupled equations for dynamic analysis of planishing mill

The dynamic properties of rolling mill are significantly influenced by many coupling factors.According to the coupled mechanical and electric dynamics theory.the global coupled equations for the dynamic analysis of planishing mill CM04 of Shanghai Baosteel Group Corporation were derived,by using finite element methods.These elasto-dynamic equations estblish the coupling relations among the stand vibration system,torsional vibration system,driving motors,etc.It provides theoretical basis to a certain extent for globally dynamic simulation,analysis of stability of motion.prediction of abnormal operating mode,globally optimum design and control,etc.     

Influences of polishing on return loss of optical fiber connectors

With Al2O3 and SiO2 as polishing medium, under different polishing conditions, e.g. with different polishing pressure, polishing time and polishing fluid, the influences of polishing treatment on the return loss of optical fiber connectors were investigated. The return loss of optical fiber connectors is 32-38 dB before polishing. The resuits show that dry polishing(i, e. no polishing fluid) with Al2O3 has less influence on return loss of optical fiber connectors, while dry polishing with SiO2 reduces return loss to about 20dB because of the end-face of optical fiber contaminated. The wet polishing(i, e. using distilled water as polishing fluid) with Al2O3 or SiO2 can increase return loss to 45-50dB, but wet polishing with Al2O3 may produce optical fiber undercut depth of 80-140nm. Wet polishing with SiO2 should be preferentially selected for optical fiber connectors and polishing time should be controlled within 20-30s.     

Rheological behavior of continuous roll casting process of aluminum alloy

The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500 - 600℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300 - 500℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300℃ and the strain rate is less than 1.00 s^-1 , it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s^-1, it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.     

基于退火遗传算法的复杂机电系统控制参数最优整定

针对复杂机电系统中可调参数多、调整范围大、参数之间耦合强、常规方法难于整定与组态的难题，提出了基于退火遗传算法的参数最优整定方法．将遗传算法和模拟退火算法巧妙地结合起来、取长补短，构成一种新的高效、鲁棒的寻优算法，应用于平整机主传动速度控制系统的参数优化问题，使系统的性能指标达到最优．     

转子系统超谐波共振的理论分析与实验研究

忽略机械系统中客观存在的非线性因素，对于提高机械故障诊断与预测的技术水平是非常不利的。本文利用多尺度法分析了刚度非线性转子系统的横向振动，论证了当转频接近于线性化固有频率的１／２或１／３时，分别存在明显的二阶或三阶超谐波共振现象，实验结果验证了理论分析的结论，本文的研究结果有有利于建立完备的回转机械故障诊断知识库。