Study on buffering performance of thin-walled metal tube with different angles

High frequency shock load is often generated during pyrotechnic device working, which is detrimental to spacecraft structures and electric devices. Therefore, it is valuable to reduce the shock load in pyrotechnic device design. Actually, there are several ways to decrease pyroshock loads, such as reduction of powder,installation of buffering structure, insulation of damageable devices, and so on. Considered assuring the function of pyrotechnic device and minimum of structure modification, shock absorbing structure is more propitious to be introduced in pyrotechnic device. In this paper, based on the method of thinwalled metal tube diameter-expanding, a thin-walled tube shock buffering structure was designed on a separate bolt. Built on the simplified structure of a separate bolt, the model of cone piston impacting thin-walled tube absorber was established, and the thin-walled tube shock absorbing characteristics and the relation between cone angles and absorber performance were analyzed. The results showed that the change of buffering force of thin-walled tube could be divided into four phases, and each phase was correspondent to the cone piston structure. In addition, as the cone angle increases, the max shock acceleration changes in the style of decrease-increase-decrease-increase, which is the result of coupled effects of cone piston max enter depth, buffering force and energy loss. In short, these results could establish the relationships between thin-walled tube absorbing performance and its structure, which is of significance to develop low-shock pyrotechnic device.

Safety evaluation system for hydraulic metal structures based on knowledge engineering

A comprehensive safety evaluation system taking the most influential factors into account has been developed to evaluate the reliability of hydraulic metal structures. Applying the techniques of AI and DB, the idea of a one-machine and three-base system is proposed. The framework of the three-base system has been designed and the structural framework constructed in turn. A practical example is given to illustrate the process of using this system and it can be used for comparison and analysis purposes. The key technology of the system is its ability to reorganize and improve the expert system＇s knowledge base by establishing the expert system. This system utilizes the computer technology inference process, making safety evaluation conclusions more reasonable and applicable to the actual situation. The system is not only advanced, but also feasible, reliable, artificially intelligent, and has the capacity to constantly grow.

Hydraulic metal structure health diagnosis based on data mining technology

In conjunction with association rules for data mining, the connections between testing indices and strong and weak association rules were determined, and new derivative rules were obtained by further reasoning. Association rules were used to analyze correlation and check consistency between indices. This study shows that the judgment obtained by weak association rules or non-association rules is more accurate and more credible than that obtained by strong association rules. When the testing grades of two indices in the weak association rules are inconsistent, the testing grades of indices are more likely to be erroneous, and the mistakes are often caused by human factors. Clustering data mining technology was used to analyze the reliability of a diagnosis, or to perform health diagnosis directly. Analysis showed that the clustering results are related to the indices selected, and that if the indices selected are more significant, the characteristics of clustering results are also more significant, and the analysis or diagnosis is more credible. The indices and diagnosis analysis function produced by this study provide a necessary theoretical foundation and new ideas for the development of hydraulic metal structure health diagnosis technology.

Filling mode and regularity of vertical centrifugal casting process of titanium alloy in thin-walled cylinder cavity

The mold filling process of titanium alloy in a thin-walled cylinder cavity under vertical centrifugal casting process was studied by means of the hydraulic simulation experiments. Results show that the filling mode of the melt in the cylinder cavity varies with casting wall-thickness. When the casting wall-thickness is less than or equal to the thickness of the first layer during the filling process, the melts fill the cavity from the bottom to the top.When the casting wall-thickness is greater than the thickness of the first layer during the filling process, the melts first fill the largest radius parts of the cavity with a certain thickness of the first layer from the bottom to the top of the cavity, and then they fill the cavity from the larger radius part to the smaller radius part. The melt filling ability increases with the increment of the mold rotational speed and the pouring temperature. In another aspect, the melt filling ability rises with the decrement of the melt viscosity, and the melt with the better filling ability is prone to fill the cylinder cavity layer by layer.

Sheet Bulk Forming of Thin-Walled Components with External Gearing through Upsetting Using Controllable Deformation Zone Method

Sheet-bulk metal forming(SBMF)is a promising process for manufacturing complex sheet components with functional elements.In this study,the entire forming process for a typical thin-walled component with external gearing is investigated,including sheet forming and bulk forming processes.Deep drawn cups are prepared during sheet forming;subsequently,upsetting is performed on the sidewall to form external gearing.The upsetting method performed is known as upsetting with a controllable deformation zone(U-CDZ).Compared with the conventional upsetting method,a floating counter punch with a counter force is used in the U-CDZ method such that the forming mechanism is changed into the accumulation of the deformation zone instead of deformation throughout the entire sidewall.The effects of the counter force and material flow are investigated to understand the mechanism.The forming quality,i.e.,the formfilling and effective strain distribution,improved,whereas a high forming load is avoided.In addition,a punch with a lock bead is used to prevent folding at the inner corner during the experiment.

弯曲载荷下双金属机械复合管内衬层屈曲失效机理

双金属机械复合管是油气田集输管线防腐控制的主要措施之一,而内衬层的失效是制约复合管工程应用的关键难题。为研究双金属机械复合管内衬层屈曲失效机理,建立弯曲载荷下复合管力学模型,研究成型压力、工作内压及复合管结构参数对内衬层失效模式的影响规律。结果表明:增加成型后的残余接触压力有助于提高内衬层的抗屈曲能力;较高的工作内压能够延缓内衬层屈曲时间,减小其褶皱幅值;成型前复合管层间初始间隙减小有利于提高内衬层抗屈曲能力;随着外基管壁厚、内衬管壁厚、复合管内径的增加,内衬管的抗屈曲能力增强。

液态金属冷却快堆子通道分析软件SACOS-LMR研发与工程应用

子通道分析方法是反应堆堆芯设计和热工水力分析的重要手段之一,对于我国提出的压水堆-快堆-聚变堆三步走核能发展战略,开发适用于液态金属冷却快堆热工安全分析的子通道分析程序具有重要意义。本文基于西安交通大学热工水力研究室自主开发的压水堆子通道程序SACOS,通过添加液态金属快堆特有的模型,如绕丝模型、盒间流模型、液态金属对流换热模型等,扩展至适用于液态金属快堆的子通道分析程序SACOS-LMR,该程序具备对液态金属快堆组件开展稳态和瞬态热工水力分析的功能。结合卡尔斯鲁厄开展的37棒钠冷瞬态实验,完成了SACOS-LMR程序的瞬态功能验证。基于验证后的SACOS-LMR程序,对欧洲铅冷快堆(ALFRED)堆芯开展了稳态工况和瞬态事故工况下的热工安全特性分析,计算结果合理,且与同类程序保持一致,表明SACOS-LMR程序可用于液态金属快堆的堆芯设计和热工水力分析研究。

水工金属结构防腐涂层附着力试验与分析

本文筛选了四种适用于水工环境的防腐涂层体系,使用两种不同表面预处理等级的金属底材,开展涂层附着力试验。通过试验结果的比对,分析不同涂层体系的特性和附着力的影响因素,为水工金属结构的防腐蚀研究提供借鉴。

简单液压加载条件下金属薄壁管摩擦因数测量方法研究

金属薄壁管液压成形技术适合于制造长径比大、周向截面复杂的中空零件,在液压成形过程中,摩擦特性和加载条件等对零件的成形过程、成形性能、零件的精度及表面质量等有显著影响。以金属薄壁管液压胀形工艺为研究对象,从胀形区中截面节点的应力和应变状态分析出发,确定金属薄壁管胀形件的摩擦分区范围,并对胀形件中截面的受力状况进行分析。针对简单液压加载情况下金属薄壁管的摩擦特性,提出一种胀形区摩擦因数的测量方法。通过简单液压加载下金属薄壁管摩擦特性试验,验证该方法的准确性,并探究摩擦因数对胀形件成形精度的影响规律。

林业汽车起重机液压缸杆密封件金属橡胶性能仿真研究

现阶段常见的橡胶密封圈在高温情况下易老化,在油液介质下易腐蚀,在高强度运输下易发生损坏。而主要应用于苛刻工况下密封领域的金属橡胶材料具有工作温度范围大、承载能力强、不易老化等特点。基于金属橡胶材料的优越性能,通过分析液压缸泄露原因,利用ANSYS分析MR组合密封件与普通O型橡胶密封性能的差异,对比不同密封件在相同边界条件下的接触应力与塑性变形,得出金属橡胶组合密封件在汽车起重机液压油缸的密封中更具有优势的结论。

基于ANSYS的粉末精整压机主机结构设计与分析

粉末精整液压机的机架刚度和强度直接影响到设备的性能以及制件的精度,本文首先通过理论经验计算对5000 kN粉末精整液压机机架的各组成部分设计结果进行了初步定量分析,其次利用有限元分析软件ANSYS Workbench在施加工况载荷条件下对主机进行仿真,得到主机机身详细的应力、应变分布云图和最大变形情况.实验结果表明液压机主机在承受工况载荷的情况下,刚度和强度能够满足设计要求,仿真结果对粉末精整液压机机架的结构优化设计有一定的指导作用,同时也为工程实践提供定量的分析参考依据.

The Additive Manufacturing Process of Electric Power Fittings Fabricated by Metal Droplet Deposition

Metal droplet deposition is a kind of additive manufacturing(3D Printing)technique that fabricates near-net part through droplets deposition with lower cost and higher efficiency.This paper proposed a solution to problems of electric power fittings that large inventories,high procurement costs,low manufacturing efficiency and transportation cost.Using additive Manufacturing technique-metal droplet deposition,electric power fittings fabricated on power construction site.This paper describes the manufacturing process of typical thin-walled samples(the structure optimized based on additive manufacturing principle)and ball head rings of electric power fittings.Aiming at the integral AM forming for ball and ball socket electric power fitting workpiece,a novel easy removal forming support material(ceramics and gypsum mixed with UV cured resin)have been developed.Here this support material was used to fabricate nested integral workpieces.Dimensional accuracy and microstructure of the test pieces were analyzed.The error of the height and width of the forming workpiece is within 5%.No obvious overlap trace(such as overlap line and cracks)observed,and the internal microstructure is equiaxial crystal.The average density of the component is 99.51%,which measured by drainage method and 13.39%higher than the cast raw material.

万米科学钻探关键机具优化措施研究

科学钻探是获取地下实物资料、认知地下结构与验证重要地质理论的有效技术手段,井下关键机具是保证钻探工程顺利实施的重要基础保障,而万米科学钻探实施过程中的井下高温、高压、长周期、大规程参数的工况与工艺要求对机具的持续稳定性提出了严峻的挑战。本文针对万米钻探工况需求,分析了钻杆柱、井下动力钻具、提速增效钻具等关键机具的结构特点和失效原因,提出了优化钻杆接头结构、设计全金属齿轮马达钻具、改进水力振荡器及射吸式扭力冲击器阀控机构、优选材质及配套表面强化技术等相应优化措施,为后续深地探测工程的实施提供技术储备。

重金属作用下改性水泥系隔离墙化学相容性研究

水泥系隔离墙被广泛应用于工业污染场地修复工程,但其防渗性能有待改善,且在高浓度、毒理性重金属污染作用下的化学相容性有待研究。通过室内试验研究了不同粒化高炉矿渣(GGBS)掺量、膨润土掺量和固化剂总掺量对水泥系隔离墙的强度和渗透特性的影响;综合考虑成墙效果和成本,选出固化剂掺量为20%(水泥、粒化高炉矿渣和膨润土掺量分别为8%、8%和4%)作为改性水泥系竖向隔离墙的最优配比。通过柔性壁渗透试验研究了重金属锌、铅污染作用下改性水泥系隔离墙试样的化学相容性。结果表明,重金属溶液作用下试样防渗性能的下降由重金属种类、重金属浓度以及试样孔隙液pH值三者共同决定。重金属种类对防渗性能的不利影响为:硝酸锌-硝酸铅>硝酸锌>硝酸铅。锌、铅溶液作用下试样的渗透系数为自来水作用下渗透系数的1.49~10.10倍,且重金属溶液的浓度越高渗透系数越大。在满足防渗要求前提下,该配比墙体材料能阻挡50 mmol/L的硝酸锌污染液、100 mmol/L的硝酸铅污染液和10 mmol/L硝酸锌-硝酸铅污染液。

基于模糊PID的开式径向变量柱塞泵控油压机系统特性实验研究

传统的大型油压机的传动系统效率和控制精度较低。在节能降耗、低碳环保的理念下,高精度泵控技术与高性能油压机控制系统的融合问题,目前已经得到了业界的广泛关注。为了提高开式径向变量柱塞泵控油压机系统的位置控制精度,设计了自适应模糊PID控制策略,并对不同工况下的快锻系统特性进行了研究。首先,建立了数字控制增强型径向柱塞泵、开式泵控非对称缸的数学模型,推导了开式径向变量柱塞泵控油压机系统的数学模型,并设计了自适应模糊PID控制器;然后,通过AMESim-Simulink联合仿真,对不同工况下带载快锻系统的控制特性展开了仿真研究;最后,依托0.6 MN泵控油压机实验测试平台,验证了自适应模糊PID的有效性以及快锻系统的控制特性。研究结果表明:在快锻频率为1 Hz、行程为20 mm、负载为1.2×10^(5)N和快锻频率为0.5 Hz、行程为40 mm、负载为2.0×10^(5)N的2种工况下,开式径向变量柱塞泵控油压机引入自适应模糊PID控制系统后,其具有运行平稳、响应迅速的特点,且位置精度误差均小于0.5 mm。上述结果验证了开式径向变量柱塞泵控油压机联合仿真模型的正确性和控制器的有效性。

金属矿床水工环地质特征及矿山开发保护探究

由于地质活动的结果是矿床,不同于普通的岩石,因而有一定的经济价值。针对金属矿床的水工地质监测工作,其地质性质的评估将直接影响到后续的开采和研究,矿区地质环境复杂,水文地质特征明显,本文就金属矿床水工环地质特征和矿山的开发与保护作了简单的论述,相信阅读本文章,也能加深您对金属矿床水工环地质特性和矿山的开发与保护有更深入地了解。

非金属壳体水压爆破试验工艺与装备的研发

非金属壳体在同等压力下的变形量远大于钢制壳体,使用针对钢制容器的普通水压试验装备和方法无法满足非金属壳体的水压检测工作,为此研发出一种适用于非金属大变形壳体的水压爆破试验工艺与装备,并进行了试样壳体水压试验、水压爆破试验,均一次性测试成功。测试和使用结果表明:该工艺和装备能够满足容积范围0.005~15 m 3、压力范围0~150 MPa的非金属壳体的水压试验与水压爆破试验,试压精度可达±0.1 MPa。试压产品规格范围广,增压速度快,压力精度高,压力曲线均匀稳定,试验数据精确可靠,能保证按照多级试压梯度一次性完成水压试验与水压爆破试验。独有的增压系统和试压工艺可有效避免因为增压速度慢、压力曲线波动、单方面数据检测误差等因素而误判产品不合格,保证了试压壳体的检测质量,节约了重复试压的经济成本和试压壳体的制造成本。投产后实际使用效果显著,对提升我国非金属壳体水压试验工艺水平有重大参考意义。

金属矿山水工环地质勘查技术的应用

“水工环”是金属矿山勘探中的重要内容,涉及水文地质、工程地质和环境地质等方面。近年来,地质灾害频繁发生,严重影响我国矿产勘查工作。因此,如果想要提高勘探效率并确保勘探准确性,则必须采用科学方法。通过对地质勘探中的水工环地质勘探技术进行深入研究,总结现场问题,并阐述金属矿山水工环地质勘查技术的适用范围,以期推动水工环地质勘探技术的可持续发展。

金属波纹管液压胀形技术应用和研究进展

采用液压胀形工艺加工成形后的金属波纹管具有厚度均匀、疲劳强度高、回弹少、表面光洁度高、尺寸精度高等优点,同时节省了材料。介绍了金属波纹管液压胀形工艺的加工过程和成形特点,阐述了电辅助成形技术用于金属波纹管加工应用原理,分析了金属波纹管液压成形质量的影响因素以及常见的成形缺陷,总结了金属波纹管液压胀形工艺在生产工艺方面的研究进展。利用有限元分析方法研究金属波纹管变形过程,可以对金属波纹管液压胀形工艺参数进行优化,并预测可能产生的制造缺陷。

水工金属结构新型环氧防护涂料性能及应用研究

水工金属结构长期处于潮湿、温度变化、水流冲蚀、气蚀等复杂不利环境,易出现结构损伤、渗透破坏等病险,严重威胁结构的正常运行。为解决传统环氧防护涂料存在的耐候性差、抗冲磨性能不佳、长期防护效果不理想等问题,根治水工金属结构病害,文章研发了适应低温、潮湿、水下环境的新型系列环氧防护涂料,研究其附着力、抗冲磨性、耐候性等性能指标,提出水工金属结构修复施工工艺,并在东坪水电站开展现场应用研究。研究表明,固化后的涂层与钢板之间的附着力达11.14 MPa,抗冲磨强度达1 017.36 h/(kg·m^(-2)),在60个人工紫外线加速循环条件下不变色,耐腐蚀性和柔韧性良好。研究成果对类似结构的防护与修复具有一定借鉴作用。