高强度螺栓断裂原因分析

对断裂的高强度螺栓进行了成分、性能及微观形貌结构等分析。结果表明，螺栓断裂为疲劳断裂及氢脆和应力腐蚀断裂．氢脆主要发生于裂纹形成初期。     

Determination of waviness decrease rate by measuring the frequency characteristics of the grinding force in centerless grinding

In centerless grinding, it is difficult to optimize the grinding conditions for minimizing the workpiece roundness error because of the high number of process parameters such as center height angle, blade angle, and stock removal rate. We had previously proposed a function for evaluating grinding conditions, i.e., the waviness decrease rate, in order to automatically select the optimum process parameters. In order to build a closed-loop control system for the process parameters, however, it is necessary to find a practical way to determine the waviness decrease rate. In this paper, the relationship between the waviness decrease rate and the dynamic components of the grinding force was investigated analytically. It was found that the frequency characteristics of the waviness decrease rate show a similar tendency to those of the grinding force. A grinding force measurement system was built and experiments for measuring the frequency characteristics of the grinding force were carried out. As a result, it was confirmed that the waviness decrease rate can be determined by measuring the frequency characteristics of the grinding force.     

Finite element prediction of material removal rate due to electro-chemical spark machining

Electro-chemical spark machining (ECSM) is an innovative hybrid machining process, which combines the features of the electro-chemical machining (ECM) and electrodischarge machining (EDM). Unlike ECM and EDM, ECSM is capable of machining electrically non-conducting materials. This paper attempts to develop a thermal model for the calculation of material removal rate (MRR) during ECSM. First, temperature distribution within zone of influence of single spark is obtained with the application of finite element method (FEM). The nodal temperatures are further post processed for estimating MRR. The developed FEM based thermal model is found to be in the range of accuracy with the experimental results. Further the parametric studies are carried out for different parameters like electrolyte concentration, duty factor and energy partition. The increase in MRR is found to increase with increase in electrolyte concentration due to ECSM of soda lime glass workpiece material. Also, the change in the value of MRR for soda lime glass with concentration is found to be more than that of alumina. MRR is found to increase with increase in duty factor and energy partition for both soda lime glass and alumina workpiece material.     

提高H13钢分流锥的使用寿命

分析了Ｈ１３钢分流锥的失效机理，研究了离子渗氮，气体氮碳共渗及常压等离子喷涂等对其使用寿命的影响。     

Research on the creep damage and interfacial failure of dissimilarmetal welded joint between 10Cr9Mo1 VNbN and 12Cr1MoV steel

0　IntroductionAnewmodified 9Cr Mosteel (SA2 13T91orT91)pos sessesimprovedhightemperaturestrength ,excellentductili ty ,weldability ,heatfatigueproperties .Therefore ,T91hasbeenwidelyusedinelectricpower,petrochemicalplant,nu clearpowerstation ,andsoon[1～3] .Itisappliedtothefinalstagesofsuperheatersandreheatersinfossil firedpowerplants .However,lowalloypearlitesteel(12Cr1MoV)isstillusedintheearlierstages .Thus,therearealotofdissimilarmetalweldedjoints (DMWJs)betweenSA2 13T91and12Cr1Mo…     

电弧热流分布模式对GMAW焊接温度场的影响

提出了ＧＭＡＷ熔池表面产生较大变形时的电弧热流分布模式,以此为基础并考虑熔滴过渡过程及焊缝余高,建立了焊接温度场的数值分析模型,通过数值模拟,定量分析了焊接工艺参数－ＧＭＡＷ熔池表面变形－电弧热流分布－熔池形态及其温度是之间的相互影响。焊接工艺试验结果,与高斯热源模型相比,采用本文给出的ＧＭＡＷ电弧热液分布模型的计算结果更符合实际。     

离心浇注不锈钢管失效原因分析

采用金相和电子探针等手段分析了离心浇注不锈钢管断裂失效的原因。结果表明，不锈钢管”鼓包”状开裂的主要原因是晶间腐蚀导致的蠕变断裂。此外，管材中发达的柱状晶低倍组织和较为严重的孔隙和裂缝等铸造缺陷的存在加速了钢管的开裂。     

水闸闸门开度显示异常故障的分析与排除

闸门控制系统故障将影响着水闸的正常运行,进而影响水闸工程效益的发挥,文章提出了闸门运行时导致闸门开度显示异常故障的原因是多样的,触摸屏、电路传输、编码器、传感器或机械传动装置任一方面出现问题都有可能导致此类故障的发生,通过分析排查确认此次问题出在机械传动装置方面,更换或修复相应的机械传动装置后排除了故障,同时分析了防止此类故障发生的有利条件或者排除此类故障的一般思路方法,确保水闸正常运行,发挥工程效益。     

防汛抢险训练场渗透破坏段设计方案试验分析

建设仿真性的防汛抢险训练场,提供有实战氛围的防汛抢险演练环境,在国内外尚属首次。为支撑江苏省防汛抢险训练场渗透破坏段方案设计,基于土体渗透破坏的基本理论并考虑到防汛演练的实际需求,首先确定用于堤坝填筑土料的料源,并对此进行了物理力学特性试验研究,根据粒径分布曲线推求非饱和渗流分析参数。然后开展两种不同比尺的水工模型渗透破坏试验,并与数值计算结果进行对比,验证数值分析的可靠性和合理性。最后对演练模型进行数值分析,根据上述试验和数值分析结果对设计方案提出相应的建议。上述设计方案基于均质土,实际填筑过程中土料的不均匀性较大,其合理性尚有待于实际工程的进一步验证。