屈服准则与重力坝超载安全系数的相关分析

有限元法的计算精度与可靠性和屈服准则的适当选择直接相关。因此,在坝体稳定性数值分析中,屈服准则的选择对重力坝超载安全系数影响较大。为了研究屈服准则与重力坝超载安全系数的本质关系,进而给数值计算中屈服准则适当选择提供理论依据,运用应力解法推导了屈服准则随着罗代角的变化与重力坝超载安全系数之间的函数关系,并运用有限元法对向家坝水利工程大坝深层抗滑稳定性进行验证与研究。研究表明内切圆锥屈服准则使得超载安全系数取得极小值,坝体最容易发生塑性流动失稳,而扩展锥屈服准则下的超载安全系数最大,坝体不容易发生塑性流动失稳     

Prediction of forming limit in hydro-mechanical deep drawing of steel sheets using ductile fracture criterion

It has been observed that the forming limit curve at fracture (FLCF) of steel sheets, with a relatively higher ductility limit have linear shapes, similar to those of a bulk forming process. In contrast, the FLCF of sheets with a relatively lower ductility limit have rather complex shapes approaching the forming limit curve at neck (FLCN) towards the equi-biaxial strain paths. In this study, the FLCFs of steel sheets were measured and compared with the fracture strains predicted from specific ductile fracture criteria, including a criterion suggested by the authors, which can accurately describe FLCFs with both linear and complex shapes. To predict the forming limit for hydro-mechanical deep drawing of steel sheets, the ductile fracture criteria were integrated into a finite element simulation. The simulation, results based on the criterion suggested by authors accurately predicted the experimetal, fracture limits of steel sheets for the hydro-mechanical deep drawing process.     

铝液充型过程水模拟技术的研究

以相似理论为理论基础，采用计算机可视化技术，分别进行了铝液、水、0．215％聚丙烯酰胺水溶液的充型可视化试验，拍摄、记录了试验过程。试验结果表明：以水作为模拟介质，从宏观上反映铝液的流动状态是可行的；但在水模拟流场的计算中，要想用水模拟流场客观真实的反映铝液的流场，使其具有更好的相似性，要适当地调整水的黏度，会使计算结果更可靠。     

双回转送进二辊冷轧管机凸轮设计研究

本文提出了双回转送进二辊冷轧管机凸轮理论轮廓曲线的新设计方法 ,其轮廓曲线加速度与跃度呈梯形 ,且跃度边界连续 ,给出了针对双回转送进二辊冷轧管机的两个过渡段具有等加速度和跃度的设计准则     

MODEL OF CLEAVAGE CRACK PROPAGATION ACROSS BOUNDARY

In the light of analysis of the features of cleavage fractographs of low carbon steel,the stresscriterion for cleavage crack propagation across ferrite grain boundary was established on thesupposition that resistance to the propagation results from an arbitrary mutual orientation ofthe cleavage plans in the neighbouring grains.On the basis of concept of statistical distribu-tion of cleavage plane in space,the probabilistic characteristic of cleavage process was ex-pounded,and the fracture stress of the cracked specimen over temperature range in whichfracture is initiated by cleavage mechanism was calculated by means of finite element analysisprogram and the calculated result was found to be in agreement with that measured.     

Lode应力参数与应力参量之间的内在联系及屈服准则的推广

从塑性力学应力Ｌｏｄｅ参数着手，深入研究了应力Ｌｏｄｅ参数与各应力参量之间的内在联系，并对塑性理论中屈服准则进行了合理推广。对塑性理论及其应用具有重要意义。     

解理裂缝过界扩展模型

根据对低碳钢解理断裂显微特征分析的结果,以相邻解理系统失配作为裂纹过界扩展的阻力源,建立了解理裂纹过界扩展的临界条件,并根据解理系统的空间分布的统计特性,对裂缝试样的解理断裂行为进行了计算模拟。计算结果与实验结果一致。     

晋东北金矿床石英流体包裹体与找矿

晋东北各种类型金矿中都广泛发育热液型石英脉，与矿化有关的石英流体包裹体的特征反映了不同的矿床类型。对该区石英脉型、蚀变岩型及磁铁石英岩型金矿床的研究表明，石英中流体包裹体的成分、温度和红外吸收光谱等特征可以作为划分矿床类型和作为金矿找矿评价的标志     

我国钢筋质量与国际先进水平的差距

回顾了我国近50年来带肋钢筋的生产状况，综述了国际上一些发达国家对普通钢筋不断提升质量水平的发展趋势及对钢筋标准的修订；并就我国在生产普通钢筋和修订标准、规范中应关注的若干问题提出了建议。     

多孔烧结材料锻造镦粗成形致密的特性研究

粉末锻造是一种新型高性能的精密塑性成形技术，但其成形时的特殊性导致目前缺乏完善的、普遍适应的粉末锻造成形理论。通过对还原铁粉烧结多孔体预成形坯锻造镦粗成形致密实验，研究了不同初始相对密度、不同高径比、不同摩擦条件对预成形坯锻造镦粗成形、致密的影响规律。得到了粉末锻造镦粗的断裂极限准则，绘制出了断裂极限应变迹线，并着重分析了初始相对密度、高径比和摩擦因子对镦粗断裂极限的影响，确定了镦粗成形极限工艺参数曲线。实验研究结果为粉末锻造预成形坯与模具的设计、工艺参数的优化奠定了理论基础，并提供了有价值的实验数据。