高强度低合金结构钢焊缝与母材的强度匹配研究

焊缝金属与母材的强度匹配系数是焊接接头力学性能非均匀参数之一，匹配方式不仅取决于焊缝金属和母材的名义强度，还取决于它们的分布形式和特征参数。试验和统计计算结果表明，12Ni3CrMoV钢和10Ni5CrMoV钢母材和焊缝金属的抗拉强度都服从正态分布。12Ni3CrMoV钢和其焊缝金属的强度匹配属于低强匹配，其低强、等强和超强匹配的概率分别为59.33%,37.03%和3.64%,低强匹配特征明显。10Ni5CrMoV钢和其焊缝金属的强度匹配属于等强匹配，其低强、等强和超强匹配概率分别为47%,48%和5%，其等强匹配分布比较明显。对应的两种钢的焊接接头，其超强匹配概率分别为3.64%和5%，在结构、焊接材料、工艺设计中值得注意。由于强度匹配系数的随机性，如何确定强度匹配系数，在什么范围内分别属于超强、等强、低强匹配，特别是等强匹配的界定方式应有别于低强和超强匹配，都是有特研究的问题。     

A numerical study of various plastically unstable behaviors in tension and compression

Various types of behavior due to plastic instability under uniaxial tension and compression are numerically investigated regarding sheet materials, plane strain blocks, and cylindrical bars and hollow cylinders. The code GOLDA for analysis of large elastic-plastic deformation previously developed by the author is used, which is one of quasi-static explicit FEM programs. Both of diffuse type and localized type of instability are concerned with. The role of vertex-hardening in plastic instability is payed attention, by using the J2G (J2-Gotoh’s corner theory) as the plasticity constitutive equation, which was proposed previously by the author and is a kind of vertex-hardening theory. Following results are mainly derived. 1) In plane strain tension, shear-type strain localization is realized by the use of J2G, but not by the conventional J2F (J2-flow theory). In axisymmetric tension of a cylindrical solid bar, however, such strain localization would never appear even by J2G, as expected by the experiment. 2) In axisymmetric tension of a hollow cylinder under the condition of no contractlion of its bore (therefore, in almost plane strain state with no circumferential strain), it is found that shear-type strain localization could occur. This is realized again by the use of J2G, whereas J2F never allows such strain localization. 3) In compression under the embedded edges condition, it is found that a sheet with initial aspect ratio of 2:1 (in height:breadth) yields double barreling, whereas a plane strain block yields double barreling at the initial aspect ratio of 3:1, not at 2:1 though expected from the conventional slip-line theory. As for a cylindrical solid bar, double barreling appears for the initial aspect ratio of 2:1 but only for higher n-vaiue (the strain hardening exponent), say n=0.5. 4) As for barreling mode, when thick-walled axisymmetric tubes with the initial ratio of thickness to inner diameter 1/5 to 1/3 are compressed axially, corresponding to the initial aspect ratios of 3:1, 2:1 and 1:1, triple barreling, double barreling and single barreling appear, respectively. 5) It is found that thin-walled tubes buckle in a progressive periodic mode with almost stationary compressive load under axial compression. Thus it can be used as a simplified model for buckling of more complex structures such as the honeycomb.     

面向小批量生产企业的成本控制方法研究

结合单件或小批量生产制造业的生产管理特点,提出在企业实施信息化的过程中体现以成本控制为主线的全过程成本控制思想,并对成本控制的环节及实施过程进行了详细论述.     

江铃汽车设备维护管理系统的开发和实现

针对江铃汽车股份有限公司的需求,依据现代设备综合管理的思想,建立了一套满足企业要求的计算机设备维护管理系统.文章就这一系统的分析、设计和实现的全过程进行了详细的论述.     

Development of a finite element analysis tool for fixture design integrity verification and optimisation

Machining fixtures are used to locate and constrain a workpiece during a machining operation. To ensure that the workpiece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped. Minimising workpiece and fixture tooling deflections due to clamping and cutting forces in machining is critical to machining accuracy. An ideal fixture design maximises locating accuracy and workpiece stability, while minimising displacements.The purpose of this research is to develop a method for modelling workpiece boundary conditions and applied loads during a machining process, analyse modular fixture tool contact area deformation and optimise support locations, using finite element analysis (FEA). The workpiece boundary conditions are defined by locators and clamps. The locators are placed in a 3-2-1 fixture configuration, constraining all degrees of freedom of the workpiece and are modelled using linear spring-gap elements. The clamps are modelled as point loads. The workpiece is loaded to model cutting forces during drilling and milling machining operations. Fixture design integrity is verified. ANSYS parametric design language code is used to develop an algorithm to automatically optimise fixture support and clamp locations, and clamping forces, to minimise workpiece deformation, subsequently increasing machining accuracy. By implementing FEA in a computer-aided-fixture-design environment, unnecessary and uneconomical “trial and error” experimentation on the shop floor is eliminated.     

Frequency response analysis of cylindrical shells conveying fluid using finite element method

A finite element vibration analysis of thin-watled cylindrical shells conveying fluid with uniform velocity is presented The dynamic behavior of thin-walled shell is based on the Sanders’ theory and the fluid in cyhndrical shell is considered as inviscid and incompressible so that it satisfies the Laplace’s equation A beam-like shell element is used to reduce the number of degrees-of-freedom by restricting to the circumferential modes of cylindrical shell An estimation of frequency response function of the pipe considering of the coupled effects of the internal fluid is presented A dynamic coupling condition of the interface between the fluid and the structure is used The effective thickness of fluid according to circumferential modes is also discussed The influence of fluid velocity on the frequency response function is illustrated and discussed The results by this method are compared with published lesults and those by commercial tools     

浅析大型铸锻件质量体系

本文主要从质量体系的产生和发展、质量体系分析的资料、质量体系的环境分析及结构型式分析几个方面探讨分析了大型铸锻件的质量体系 ,可供大型铸锻件生产厂按 ISO90 0 0系列标准分析、设计、建立和完善大型铸锻件质量体系时参考。     

烧结炉中20g钢冷却管爆裂分析

对烧结炉中２０ｇ钢冷却管爆裂所进行的检验确认爆裂原因是冷却水量小及水质差引起堵塞，造成过热过烧。建议软化水质和改进冷却系统为解决途径。     

苏州市既有公共建筑运行能耗调查与分析

通过对苏州市既有公共建筑运行能耗进行调查统计及室内环境测试,并对数据进行系统分析,反映苏州市大型公共建筑的部分实际能耗状况,在此基础上提出节能改造措施,对苏州市既有公共建筑节能改造有一定的参考价值。     

新疆华誉时代广场A座—超限高层设计

新疆华誉时代广场A座位于新疆库尔勒市,结构主体高度约为149.5m,结构形式采用带部分框架柱的剪力墙结构,包含地下2层,地上39层,局部出屋面。结构平面布置有斜交构件,较不规则,结构沿竖向无刚度突变及抗剪承载力突变。总体判断结构沿竖向布置较为规则,无明显薄弱层。结构根据国家《超限高层建筑工程抗震设防专项审查技术要点》(建质[2010]109号)判断为高度超限的高层建筑。本工程初步设计分别经过了全国超限高层审查委员会及新疆自治区的超限高层审查委员会审查通过。结构设计采用了多种计算软件的对比分析,并进行了小震下的弹性时程分析、大震下的弹塑性静力分析,并对结构设定了性能控制指标,对剪力墙、框架柱等重要构件进行了中震(不屈服、弹性)计算设计。本文着重介绍了该工程上部结构的计算分析及设计要点。