MTS软件中J积分测试存在的几个问题及建议

MTS软件以其在断裂疲劳方面的准确方便著称,但在J积分测试上却存在着一些难以直接获得有效数据的问题。该文列举了MTS软件在处理存在裂纹扩展"负增长"、分叉和止裂等现象的阻力曲线时测试结果不准确的现象,并讨论了不同标准中钝化线斜率定义不同导致得到的断裂韧度指标无法比较的问题。最后针对MTS软件J积分测试中存在的问题给出了相应的建议和解决方法。     

对J积分测试中钝化线形式的探讨

根据J积分与路径无关性原理,提出了起裂点的J Δa0关系式:J=(1/1+n)Kε1+nf×2Δa。通过对16Mn钢的J积分测试,认为该式计算的Δa0与实测钝化带宽度符合得比较满意。     

稳态扩展裂纹前缘形态的研究

利用超声波断口图技术对不同类型的带单侧贯穿裂纹的PMMA试件进行了测试,得到试件断口上的超声波线。基于ANSYS软件的有限元分析,计算了试件的三维J积分,得到的试件在不同裂纹长度下的三维J积分与它们断口图上的超声波线的形状和凸凹方向相似,将试件扩展裂纹前缘由直线调整为特定曲线后,计算出的三维J积分趋向常量,证实了扩展裂纹前缘的任一点,J积分矢量的幅值都是相同常量的假设。     

0Cr18Ni9不锈钢板启裂韧度的测定

参考GB/T 21143-2014多试样法设计试验,采用钝化线法和钝化区宽度法测定了0Cr18Ni9不锈钢板的启裂韧度Ji,并利用声发射技术对试验过程进行了监测。结果表明:与钝化线法相比,利用钝化区宽度法测定的0Cr18Ni9不锈钢板材启裂韧度Ji更接近真实值。根据声发射测试结果分析了不锈钢板的断裂过程,并结合钝化区宽度法确定其启裂韧度Ji=351.77kJ·m-2。     

含半椭圆表面裂纹焊接接头断裂参量的试验研究

本文研究了半椭圆形表面裂纹最深点三维J积分的直接测试技术,并在此基础上,通过对高匹配焊接接头表面裂纹试样断裂力学参量J积分的试验测试,探讨了接头强度匹配对焊接表面裂纹扩展驱动力的影响。试验表明本文所采用的手段对于焊接表面裂纹断裂参量的测试是适用的,且结果也充分反映出焊接接头的力学性能不均匀性的影响作用。     

传感器阵列六自由度振动测试数值积分误差消除方法研究

利用多个加速度计组成的传感器阵列进行复杂振动测试,多组加速度计测试值可求解被测物质心线加速度及相对载体坐标系三轴方向转动角速度。对角速度、线加速度积分可求解被测物任意时刻相对于固定坐标系位置及姿态,达到六自由度复杂振动测试目的。针对积分过程中存在积分误差及随测试时间增加积分误差迅速增大导致速度、位移信号严重偏离实际问题,利用EMD分解获得多组经验模态分量(IMF),据IMF分量频率不同判断出积分误差成分并分离,获得实际积分结果。     

不锈钢植酸钝化工艺及其耐腐蚀性能研究

通过极化曲线,AFM和红外光谱测试,研究了钝化工艺参数对不锈钢植酸钝化膜耐腐蚀性能的影响,得到了最优的钝化处理工艺,获得了耐腐蚀性能更优良的钝化膜。该方法原料来源广泛、价格低廉,工艺操作方便,而且钝化过程中不产生有毒有害物质,是一种高效环保型的不锈钢钝化处理方法。     

拉弯联合载荷下弹塑性J积分估算方法研究

基于计算J积分的等效原场应力方法,利用等效原场应力σeff只有外加载荷意义而不再具有拉伸或者弯曲等载荷类型方面的属性,提出了利用现有含裂纹结构的纯拉伸以及纯弯曲J积分全塑性解直接计算拉弯联合载荷下的J积分简化估算方法。该方法可以直接利用已经存在的J积分纯拉伸和纯弯曲全塑性解来计算拉弯联合载荷下的J积分,简化了拉弯联合载荷下J积分全塑性解的计算;并且可以应用于任意应力-应变材料,包括Ramborg-Osgood关系的材料和任意单调加载非R-O关系材料。计算过程简便。并通过与有限元计算结果对比对之进行验证,说明其工程实用性,为对含裂纹结构进行弹塑性断裂评定奠定基础。     

铜在甲胺-铁氰化钾化学机械抛光液中的腐蚀与钝化

用电化学测试技术研究了腐蚀介质和成膜剂浓度对铜表面的腐蚀与钝化成膜的影响,分析了钝化膜的成分,探讨了钝化膜在抛光压力和转速作用下的磨损与表面再钝化的行为,测量了铜在化学机械抛光过程中的极化曲线。结果表明铜在甲胺溶液介质铁氰化钾抛光液中易钝化,钝化膜的主要成分为Cu4[Fe(CN)6],有少量Cu20存在。钝化膜的磨损特性随成分浓度不同而不同。钝化膜的磨损难易程度与钝化膜的本身特性、抛光压力及转速有关。抛光过程中因钝化膜被磨损,腐蚀加快,腐蚀电流密度大幅增加。配方0．1％甲胺溶液 0．5％K3Fe(CN)6 5％Al2O3可行。     

稀土铈对镀锌层三价铬彩色钝化膜的影响

为了提高镀锌层三价铬彩色钝化膜的性能,通过单因素试验和对比分析的方法研究了稀土铈盐对三价铬彩色钝化膜的影响。研究发现在三价铬彩色钝化液中添加硫酸铈1.5 g/L时,钝化膜的表面质量及耐腐蚀性能最好。对比三价铬钝化膜及含铈三价铬钝化膜的外观颜色,发现稀土铈盐的添加加深了彩色钝化膜的色泽,提高了钝化膜的亮度及均匀性。从金相显微镜和扫描电镜(SEM)分析可知,2种钝化膜膜层明显,且含铈钝化膜的表面致密度更高。通过能谱仪(EDS)分析可知,稀土铈元素参与了成膜过程。黏着力测试和电化学测试表明,含铈三价铬钝化膜有较好的耐磨性和耐蚀性。初步分析镀锌层三价铬彩色钝化膜的成膜过程可知,成膜反应和溶解膜反应形成了一个动态平衡过程,通过控制钝化浸渍时间和钝化液的p H值,控制钝化膜的溶解,可以提高钝化膜的致密性。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from