回火对Q460E低合金结构钢组织与性能的影响

研究了回火温度对正火Q460E低合金结构钢的力学性能与组织影响.结果表明,在200℃到500℃范围内回火,力学性能相对较为稳定且具有较高的强韧性,而且屈强比也比较低,回火温度升高到600℃,力学性能虽相对较低,但钢的强韧性要比GB/T1591-1994(国标)规定的要高.分析认为:600℃回火强韧性降低幅度相对大的原因主要是粒状贝氏体的分解,碳化物的析出长大球化且分布在条状铁素体边沿,犹如上贝氏体,以及碳化物在原奥氏体晶界分布.200℃回火能够获得较高的强度和突出的韧性.回火过程就是粒状贝氏体分解变化,碳化物析出长大球化过程.     

广义共轭留数边界元法电除尘器电场解析

将广义共轭留数法引入于边界元法，改变矩阵方程与高斯消去法相结合的原传统结构，按照指数函数规律缩短解题时间。自由度数越多其效果越显著。仅就电除尘器电场和电势的小规模数值结果，与实验结果相符。证明这种方法是有效的，计算速度比传统的边界元方法快两倍。     

螺纹副面力场的摩擦接触多极边界元解析(3500中厚板轧机压下系统可靠性研究Ⅱ)

将三维弹性摩擦接触多极边界元法及软件应用于3500中厚板轧机压下螺纹副三维面力场的大规模运算课题。通过微机运算，给出了螺牙接触面的径向压力分布、径向摩擦力分布、周向压力分布和螺纹层间压力分布。在获得同等计算精度条件下，和有限元法相比，本法占用的CPU时间相当，但所用微机内存容量仅为有限元法的1／80。     

Mathematical Programming Solution for the Frictional Contact Multipole BEM

IntroductionElastic friction contact problems require accuratetracking of the movement of objects before and aftercontact and the interaction during contacts and correctsimulation of the frictional behavior between the con-tact surfaces. The boundary element method (BEM)[1,2]is well suited to accurately describe the variation of thefrictional contact conditions since the highly nonlineareffects only occur on the contact surface. For nonlinear frictional contact, various approacheshave been …     

金属/电介质多层膜的光学特性

在Ｄｒｕｄｅ模型的基础上,计入金属薄膜表面对传导电子弛豫时间的影响,计算了金属的介电函数和光学常数,并利用结构特性矩阵方法计算了金属／电介质多层膜的反射率和吸收率,讨论了金属层厚度、层数对反射率和吸收率的影响     

Multipole BEM for 3-D Elasto-Plastic Contact with Friction

The analysis of 3-D elasto-plastic contact with friction is a highly nonlinear problem. The elements in the contact and plastic zones should be refined to obtain accurate information about the real size,displacement, and traction in the contact zone. However, the increase in the number of degrees of freedom is limited when traditional boundary element method (BEM) is used with the larger memory size and long CPU time required for the solution procedure. This paper describes the additional mathematical friction model to the 3-D elastic multipole BEM to develop a 3-D elasto-plastic contact multipole BEM. Numerical tests show that with this new method, the needed computer memory size is only 2% of the traditional BEM model with friction, which erases large-scale computing with refined meshes and improves the computational accuracy.     

Mathematical Programming Solution for the Frictional Contact Muitipole BEM

This paper presents a new mathematical model for the highly nonlinear problem of frictional contact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic contact with friction to replace the Monte Carlo method. A numerical example shows that the optimization programming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative to the conventional BEM.     

接触问题中的边界元法及其最优罚因子

分离解法在种类上类似于柔度法,但在接触区附近考虑面力对位移的影响。对每个外载荷的增量迭加进行分析,适合那些面力变化的方程,用面力来区分接触状态。在判别接触状态时罚因子w的选择很重要,选取的好可得到快速的收敛解,否则得不到收敛解,对接触问题中的分离解法人出了最优罚因子w,并通过实验验证了方法的正确性。     

兽医外科手术学教学中培养学生素质的探讨

《兽医外科手术学》是一门实践性极强的学科,要求教师在教学过程中,注重外科手术素养、外科技能素质、心理素质、职业道德素质、人文素质的培养,并需培养学生正确的临床思维能力和创新发展观,以适应现代临床兽医学诊疗的发展需要。     

高分子统计理论中的排除体积链

本文就一种简单的排除体积链模型,介绍了目前处理该种链的几种方法,并对各种方法及结论进行了分析、比较,为处理更复杂的模型奠定了基础.