基于Ls-Dyna的高能射流式冲击器活塞杆回程应力分析     

王福平  李鹏  李国琳  彭枧明 《吉林大学学报(地球科学版)》2016,46(5):1482-1489

针对在钻探实践中高能射流式冲击器的活塞杆频繁出现尾部塑性变形严重影响冲击器工作性能和整体寿命的现象,拟对活塞杆进行优化改进。利用非线性动力学仿真软件Ls-Dyna对活塞杆的回程撞击缸体进行数值模拟和优化分析,并进行了室内试验,结果表明：冲击末速度为4 m/s,活塞杆回程撞击缸体强制停止运动瞬间,尾部产生的应力集中值为3 339.28 MPa,导致其破坏;优化改进后,活塞杆上下端直径比为17/16、尾部圆弧直径为60 mm,活塞杆体内的应力集中值为1 419.66 MPa,较改进前活塞杆的应力集中值减小58%。试验验证表明,优化后的活塞能大幅提高使用寿命和耐久性。  相似文献   

Ice- and cryogel-soil composites in water-retaining elements in embankment dams constructed in cold regions     

N. K. Vasiliev  A. A. Ivanov  I. N. Shatalin  V. V. Sokurov 《寒旱区科学》2013,5(4):0444-0450

There are a number of serious problems connected with building and repairing water-retaining elements in embankment dams in cold regions. One of them is the difficulty in finding inexpensive clay materials with the necessary structural properties and using them in the winter. Another is the cracks that appear in the upper part of a dam when the core freezes to the banks, and leakage along the cracks threatens to destroy the dam. Still another is the process of erosion at the bottom of the core which may occur through fissures in the rock foundation of a dam and in transport constructions. Also, the behaviour of water-retaining elements during earthquakes is unreliable. All of these problems can be solved by using ice- and cryogel-soil composites created by cryotropic gel formation (CGF). Our laboratory investigations demonstrate that the materials proposed for water-retaining elements have the necessary permeable, plastic, thermophysical, and strength properties to solve all of these problems. Certain constructions of water-retaining elements which may prove to be both safe and cost-effective are proposed. However, these ice- and cryogel-soil composites need to be field-validated before they are used in dams and transport structures in cold regions.  相似文献   

Public concern about,and desire for research into,the human health effects of marine plastic pollution: Results from a 15-country survey across Europe and Australia     

《Global Environmental Change》2021

Marine plastic pollution is caused by humans and has become ubiquitous in the marine environment. Despite the widely acknowledged ecological consequences, the scientific evidence regarding detrimental human health impacts is currently debated, and there is no substantive evidence surrounding public opinion with respect to marine plastic pollution and human health. Results from a 15-country survey (n = 15,179) found that both the European and Australian public were highly concerned about the potential human health impacts of marine plastic pollution, and strongly supported the funding of research which aims to better understand its health/wellbeing implications. Multi-level modelling revealed that these perceptions varied across socio-demographic factors (e.g. gender), political orientation, marine contact factors (e.g. marine occupation and engagement in coastal recreation activities) and personality traits (e.g. openness, conscientiousness and agreeableness). Quantifying attitudes, as well as understanding how individual-level differences shape risk perception will enable policy makers and communicators to develop more targeted communications and initiatives that target a reduction in marine plastic pollution.  相似文献   

Photographic assessment of retroreflective film properties   总被引：1，自引：0，他引：1  

G. BurgessM.R. Shortis  P. Scott 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(5):743-750

Retroreflective film is used widely for target manufacture in close-range photogrammetry, especially where high precision is required for applications in industrial or engineering metrology. 3M Scotchlite 7610 high gain reflective sheeting is the gold standard for retroreflective targets because of the high level of response for incidence angles up to 60°. Retroreflective film is now widely used in the transport industry for signage and many other types of film have become available. This study reports on the performance of six types of retroreflective sheeting, including 7610, based on published metrics for reflectance. Measurements were made using a camera and flash, so as to be directly applicable to photogrammetry. Analysis of the results from this project and the assessment of previous research indicates that the use of standards is essential to enable a valid comparison of retroreflective performance.  相似文献   

Physical and chemical effects of ingested plastic debris on short-tailed shearwaters, Puffinus tenuirostris, in the North Pacific Ocean     

Yamashita R  Takada H  Fukuwaka MA  Watanuki Y 《Marine pollution bulletin》2011,62(12):2845-2849

We investigated the plastics ingested by short-tailed shearwaters, Puffinus tenuirostris, that were accidentally caught during experimental fishing in the North Pacific Ocean in 2003 and 2005. The mean mass of plastics found in the stomach was 0.23 g per bird (n = 99). Plastic mass did not correlate with body weight. Total PCB (sum of 24 congeners) concentrations in the abdominal adipose tissue of 12 birds ranged from 45 to 529 ng/g-lipid. Although total PCBs or higher-chlorinated congeners, the mass of ingested plastic correlated positively with concentrations of lower-chlorinated congeners. The effects of toxic chemicals present in plastic debris on bird physiology should be investigated.  相似文献   

克拉玛依科博馆倾斜结构抗震设计     

赵楠 《地震工程与工程振动》2011,31(2):111-117

结合克拉玛依市科技博物馆工程,对超限倾斜结构设定性能设计目标,并针对性能目标提出抗震措施及抗震构造措施.考虑结构材料的非线性属性,采用静力非线性分析方法,分析倾斜框架-剪力墙结构在地震作用下的响应,尤其是结构在罕遇地震作用下的非线性动力特性.结果表明,结构在罕遇地震下也是安全可靠的,剪力墙尚处在弹性范围,未出现塑性铰,...  相似文献   

泥沙颗粒生长生物膜后起动的实验研究——Ⅱ.起动流速计算   总被引：1，自引：0，他引：1       下载免费PDF全文

方红卫  尚倩倩  府仁寿  何国建 《水科学进展》2011,22(3):301-306

泥沙颗粒生长生物膜后,起动流速发生了较大变化.根据生长生物膜后的泥沙起动流速实验数据,考虑天然水体中,生物膜填充于颗粒与颗粒之间形成除水以外新的介质,将生物膜的作用模化为生物膜作用产生的粘连力,再考虑生物膜随时间变化的特性以及基底物理特性的影响等因素,结合泥沙颗粒之间由于薄膜水产生的黏结力、重力等,研究了颗粒在滑动和滚...  相似文献   

老挝万象平原钾盐矿床控矿构造研究   总被引：1，自引：0，他引：1  

王少华 《化工矿产地质》2011,33(1):41-45

老挝万象平原钾盐矿层赋存于新近系古新统塔贡组中,主要含钾矿物为光卤石,少量钾石盐.成矿期塔贡组及钾盐矿层主要受北西向的边界断裂及塔贡向斜控制;成矿期后钾盐矿层主要受褶皱(盐向斜、盐背斜)控制.在钾盐矿层沉积后,先在水平应力作用下形成宽缓褶皱.由于向斜部位相对沉降,沉积速度较快,钾盐矿层上部的碎屑岩较厚;而背斜部位相对上...  相似文献   

海南石碌铁矿床构造变形特征及其与铁多金属成矿富集的关系   总被引：1，自引：0，他引：1  

许德如  吴俊  肖勇  陈福雄  王力  刘朝露  王智琳 《地质通报》2011,30(4):553-564

海南石碌铁矿曾被誉为“亚洲最大的富铁矿”,其形成、定位与褶皱变形及伴随的剪切、塑性流动等构造密切相关。石碌矿区构造变形大致分为早期(D1)复式向斜的形成时期、晚期(D2)褶皱叠加和剪切变形时期。后者又进一步分为韧-脆性变形(D2a),脆-韧性变形、层间滑脱断层形成(D2b)和脆性变形、矿体破坏(D2c)3个阶段。石碌铁矿床受NW—SE向复式向斜及其与NE—NNE向褶皱叠加所形成的横跨或斜跨褶皱的严格控制;褶皱过程所伴随的剪切变形和高温塑性流动是富铁矿形成的重要机制。复式向斜轴部,尤其是2期向斜褶皱轴的叠加部位往往可发现厚大的富铁矿体。  相似文献   

Pseudo‐dynamic test of a full‐scale CFT/BRB frame—Part II: Seismic performance of buckling‐restrained braces and connections     

Keh‐Chyuan Tsai  Po‐Chien Hsiao 《地震工程与结构动力学》2008,37(7):1099-1115

This paper is Part II of a two‐part paper describing a full‐scale 3‐story 3‐bay concrete‐filled tube (CFT)/buckling‐restrained braced frame (BRBF) specimen tested using psuedo‐dynamic testing procedures. The first paper described the specimen design, experiment, and simulation, whereas this paper focuses on the experimental responses of BRBs and BRB‐to‐gusset connections. This paper first evaluates the design of the gusset connections and the effects of the added edge stiffeners in improving the seismic performance of gusset connections. Test results suggest that an effective length factor of 2.0 should be considered for the design of the gusset plate without edge stiffeners. Tests also confirm that the cumulative plastic deformation (CPD) capacity of the BRBs adopted in the CFT/BRBF was lower than that found in typical component tests. The tests performed suggest that the reduction in the BRB CPD capacities observed in this full‐scale frame specimen could be due to the significant rotational demands imposed on the BRB‐to‐gusset joints. A simple method of computing such rotational demands from the frame inter‐story drift response demand is proposed. This paper also discusses other key experimental responses of the BRBs, such as effective stiffness, energy dissipation, and ductility demands. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献