刚构连续弯板桥空间有限元分析

随着高等级公路的兴建和城市建设的进一步发展,平面曲线桥梁应运而生,刚构连续弯板桥成为有力竞争桥型之一．为了研究刚构连续弯板桥的空间受力特性,本文结合一实例刚构连续弯板桥,针对平面软件分析弯桥的不足,首先利用通用有限元软件ANSYS进行整体建模分析,整体分析中不考虑普通钢筋的建模,接着用专业软件桥梁博士对截面进行计算复核．从实际运营情况看,复核结果是合理的．     

连铸板坯内部裂纹的研究分析

通过分析连铸板坯中内部裂纹的形成原因，针对济钢板坯内部裂纹的表现形式和级别，提出了减轻内部裂纹缺陷形成的措施。     

重轨矫直变形过程的有限元模拟计算分析

采用ANSYS/LS-DYNA有限元软件,对重轨钢矫直过程进行了有限元模拟研究.重轨在计算机模拟矫直过程中,轨头、轨底、轨腰在各变形区内所产生的残余应力状态符合实际矫直情况.计算结果表明,轨底、轨腰、轨头在不同的变形区内残余应力变化显著,其应力状态以拉-压-拉的形式变化.     

Effect of cooling structure on thermal behavior of copper plates of slab continuous casting mold

A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30℃ and 15℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 mm, respectively. The surface temperature without nickel layers is depressed by 10℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.     

基于小波有限元法的虚拟裂纹闭合法

为了弥补传统有限元在处理复杂结构断裂参数数值计算中的不足,将小波有限元应用到断裂力学数值计算中,提出了一种新的基于小波有限元的虚拟裂纹闭合法。该方法将哑节点断裂单元镶嵌到含裂纹结构的小波有限元模型中,利用虚拟裂纹闭合法计算能量释放率和应力强度因子。将计算结果与传统有限元和ANSYS模拟结果比较。结果表明:2个小波单元求解结果与传统有限元和ANSYS模拟结果基本吻合,与解析解相对误差不超过3%,表明该方法具有计算量小、方法简便和计算精度高的优点,为工程中复杂结构断裂参数数值计算提供了一种新方法。     

Heat-transfer model on the improvement of continuous casting slab temperature

A heat transfer model on the solidification process has been established on the basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & Steel Corporation, and the temperature field in the solidifying slab was calculated which was verified by the measured slab surface temperature. The influences of the main operating factors including casting speed, spray cooling patterns, superheat of melt and slab size on the solidification process were analyzed and the means of enhancing the slab temperature was brought forward. Raising the casting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving the cooling pattern at the lower segments of secondary cooling zone could improve the slab temperature effectively. And the increasing the superheat is adverse to the production of high temperature slab.     

Longitudinal surface cracks on continuous casting slabs of P and Cu containing container steel

The fact that the amount of the mold flux components differs at different locations on the cracking surface indicates that the longitudinal surface cracks are initially formed in the mold and are enlarged in the secondary cooling zone. Based on the hot ductility measurement of two typical container used steels, it is known that the steels are in severe embrittlement state in the temperature range of 825-775℃. By means of increasing Cr/Ni plating thickness on the upper part of the mold, reducing mold heat flux, adopting new secondary cooling pattern, etc., the occurrence of the surface longitudinal cracks on the steel CC (continuous casting) slabs has been significantly reduced.     

水压裂纹扩展有限元法分析及计算

通过分析油气开采水力压裂技术的具体特点以及有限元数值模拟方法 ,计算出裂纹延伸情况 ,从而度量出油气井的有效开采范围 ,进而对精确开采进行可行性分析 .经华北油田某采区钻井的实地检验 ,以该方法得出的裂纹扩展预测值比实际值平均高出 8.7% ,说明此方法对预测油气井开采中的水压裂纹扩展延伸情况是一种较为有效的方法     

Characteristics of shell thickness in a slab continuous casting mold

The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold.A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid (VOF) model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions.The results show that the jet acts a stronger impingement on the shell of narrow face,which causes a zero-increase of shell thickness in a certain range near the impingement point.The thinnest shell on the slab cross-section locates primarily in the center of the narrow face,and secondly near the comer of the wide face.Nozzle optimization can obviously increase the shell thickness and make it more uniform.     

方坯凝固过程中铸坯热应力分析

根据大方坯连铸的凝固和变形过程的特点，应用三维非稳态热弹性有限元数学模型模拟了模拟了大方坯凝固时坏壳的应力场分布情况了凝固坯壳的变形情况，为预测裂纹缺陷提供了理论依据。     

Water modeling of mold powder entrapment in slab continuous casting mold

The optimal parameters were determined by the water modeling of slab casting. It was found that there are mainly three types of mold powder entrapment in slab continuous casting, i.e., the entrapment caused by the shearing flow near the narrow face of mold, the entrapment caused by vortexes around the submerged entry nozzle (SEN), and the entrapment caused by the Ar bubbling. Both the velocity of the surface flow and the level fluctuation of the liquids are enlarged with increasing the casting speed, reducing the submersion depth of SEN, decreasing the downward angles of the nozzle outlets, and increasing the Ar flowrate, all of which in- crease the tendency of mold powder entrapment. Among the four above-mentioned factors, casting speed has the largest effect.     

Effects of the width and thickness of slabs on broadening in continuous casting

A 3D viscoelastic-plastic thermal-mechanical coupled finite element model was built on the basis of the secondary development of the commercial software MSC.Marc. Numerical simulations were performed to study slab broadening in the secondary cooling zone. The effects of slab width and thickness on slab broadening were considered. The obtained results reveal that the width broadening is noticeable, and the ratio of ultimate broadening slightly increases with the increase of slab width. This agrees well with the measured data in practice. There is no obvious increase in ultimate broadening when the thickness of slabs increases.     

Temperature distribution and dynamic control of secondary cooling in slab continuous casting

To predict and optimize the temperature distribution of slab continuous casting in steady operational state, a three-dimensional model (named offline model) based on the heat transfer and solidification theories was developed. Both heat transfer and flux distribution characteristics of the nozzle sprays on the slab were considered, and the complicated boundary condi-tions, such as spray cooling, natural convection, thermal radiation as well as contact cooling of individual rolls were involved in the model. ...     

Q345D板坯连铸凝固传热过程数值模拟

基于凝固传热学理论,以300 mm厚Q345D板坯连铸过程为研究对象,建立了板坯二维凝固传热数学模型。利用等效比热法对凝固潜热进行处理,分析了拉速、过热度、二冷区喷水量以及二冷区长度变化对出结晶器坯壳厚度、铸坯表面温度等凝固参数的影响。结果表明,适当提高拉速、降低过热度和增加二冷段长度,可以促进连铸坯凝固,降低板坯缺陷,提高生产效率。     

宽板坯凝固前沿轻压下率模型的研究

结合连铸坯凝固规律及轻压下技术改善铸坯中心偏析的冶金原理,建立宽板坯轻压下率理论模型。根据某厂连铸宽板坯实际生产条件,以传热模型计算的铸坯凝固温度数据作为轻压下率模型计算条件,分析拉速、浇注温度、坯壳凝固收缩特性对铸坯轻压下率的影响规律。结果表明,在相同的拉速和浇注温度条件下,铸坯轻压下率沿拉坯方向的分布总体呈减小趋势;拉速较高时的起始轻压下率小于拉速较低时对应的起始轻压下率;拉速与平均轻压下率呈线性递减关系：拉速每升高0.1m/min,平均轻压下率减小0.015mm/m;浇注温度越低,轻压下区起始轻压下率的值越高;浇注温度对平均轻压下率的影响较小,浇注温度每升高10℃,平均轻压下率仅减小0.002 5mm/m;铸坯外部凝固坯壳的收缩对整个轻压下区平均轻压下率的贡献量为20.4%～22.3%。     

Strain in solidifying shell of continuous casting slabs

Two-dimension unsteady heat transfer model was applied to obtain the surface temperature and the shell thickness of continuous casting slabs during the process of solidification. On the basis of which, the mathematical model of strain at the interface of solid and liquid steel was set up. Through which, the strain in the solidifying shell under normal and abnormal operation conditions was gained. The results indicate that the strain is small under the normal operation conditions and the internal crack never happens. However, when the variation of the roll gap is above 2 mm, the strain caused by which is greater than that caused by bulging. Furthermore, the total strain exceeds the critical one and the internal crack is the result. So it is of great importance to maintain the fine state of continuous casting machine to avoid the appearance of internal crack.     

连铸坯质量判定专家系统的研发

利用工业生产数据作为样本,结合某中厚板厂的实际生产状况与中厚板热送热装的控制要求,以表面纵裂为例,按照专家系统的开发思路,建立连铸坯纵裂知识库,利用正向推理机制,对连铸坯质量进行离线判断、推理和决策,并给出相应的缺陷产生原因解释。采用VisualC＋＋6．0软件建立人机界面,数据库采用Oracle,并完成系统的离线调试,系统可以达到较高的判定准确率（大于92．2％）和较低的漏判率（小于10％）,为在线调试及生产做好准备。     

An efficient wavelet finite element method in fault prognosis of incipient crack

Typical structural damage is evidenced by emergence and expansion of incipient crack that is not easy to detect[1]. The crack fault is one of the major causes for damage of the large-scale complicated structure. A serious consequence of expanding crack is frequent occurrence of grave accidents. As a consequence, one of the important orientations in the field of fault diagnosis is to monitor and prognose the location and depth of incipient crack. Prognosis of the incipient fault is a new subjec…     

压铸机锁模机构的接触非线性有限元分析

运用ANSYS对压铸机锁模机构的合模工况进行了有限元分析,介绍了接触问题中的增强拉格朗日算法、有限元模型建立、接触对的建立,探讨了实常数FTOLN,FKN,最后对有限元结果进行了评估.     

连铸薄板坯表面变形实验研究

对连铸薄板坯的坯壳表面变形进行了物理模拟实验，提出一种“铜裹铅双金属”新实验方案，并用视塑性方法对实验结果进行了分析。