关键词： 燕山大学   控制实验室   重型机械   重点实验室   固定研究人员   流体动力传输   博士生导师   重点学科实验室  

摘要： 燕山大学重型机械流体动力传输与控制实验室的前身为东北重型机械学院液压实验室,始建于1977年。2005年,实验室成为河北省重型机械流体动力传输与控制重点实验室,2006年成为国防重点学科实验室,2007年成为机械工业流体动力传输技术重点实验室。实验室现有固定研究人员34名,其中教授13人(含博士生导师10名),副教授9人。

关键词： 机械手   动力学性能   有限元分析   模态分析  

摘要： 对物流货物抓取机械手进行动力学性能分析,利用有限元软件ANSYS Workbench建立机械手关键部位的仿真模型,对大臂、小臂构件进行危险工作状态下的有限元分析,并对该机械手构件的结构进行模态分析。结果表明,该机械手关键部位的结构和材料均满足工作性能要求,机械手中的大臂、小臂构件在作业过程中不会产生共振现象,具有良好的动力学性能。

关键词： 纯电动汽车   动力锂离子蓄电池   机械性能测试   荷电状态  

摘要： 动力锂离子蓄电池作为电动汽车的主要零部件之一,与车辆安全密切相关,必须经过一系列安全测试。分析了GB38031—2020与UL、FreedomCAR、SAE等美国标准对锂离子动力蓄电池在机械安全方面的测试要求,对翻转试验、振动试验、机械冲击试验、跌落试验、挤压试验、针刺试验、浸水试验中的试验方法和参数进行比较分析。指出不同标准之间因试验条件的不同而不具有可比性,以及相关标准存在的不足。

关键词： 金工实习   学习动力   实践操作  

摘要： 金工实习是一门实践基础课,其对锻炼学生的动手能力,培养学生的创新精神,提高学生的综合素质,起着重要的作用。在实践教学过程中发现,非机械类专业的学生在金工实习的过程中往往表现出对该门课程的学习和实践操作动力不足,如此问题的存在,对学生动手能力的提高会产生消极影响。本文在找到非机械类专业学生金工实习存在学习动力不足的问题后,分析了产生该问题的原因,之后介绍了实践教学中对于提高非机械类专业学生金工实习学习动力效果较好的教学方法,旨在为金工实习教学中提高学生的学习和实践操作动力,提供思路借鉴。

关键词： 农业机械化   农业   劳动力   转移贡献   量化  

摘要： 农业机械化对农业整体生产条件、农村地区生态环境及农民的生活水平均可起到改善作用,对于农村地区劳动力的转移贡献也有着一定影响。基于此,笔者针对农业机械化转移农村地区劳动力的贡献进行量化分析,以便为后期更多研究提供有价值的参考。

关键词： 2.25Cr-1Mo steel   Precipitation   Isothermal heating   Cyclical heating   Mechanical property  

摘要： The carbide precipitation was analyzed during aging of 2.25Cr–1Mo steel at 550℃.The as-received steel was aged in two different manners:the first treatment was an isothermal aging at 550℃ for time up to 1000 h,and the second one was carried out by a cyclical aging,which consisted of aging at 550℃ for 1 h,water quenching at room temperature and then newly heating at 550℃.This procedure was repeated up to 300 *** M_(23)C_(6) and M6C carbide precipitation took place intragranularly and intergranularly for both aging *** carbide coarsening was detected to occur with the increasing aging ***,the growth kinetics of precipitation occurred more rapidly in the case of cyclical *** specimen hardness decreased with the aging time in both cases;however,it occurred in shorter aging time for the cyclical *** testing indicated the increase in ductility with the aging time,and the cyclically aged specimens showed larger ductility than the isothermally aged specimens.

关键词： Quasi-static&dynamic compression   Phase transformation   Deformation structures   Dislocation slips   Grain boundary sliding  

摘要： Most of the structural alloys’applications are under static,dynamic,and cyclic forms of ***-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic *** Ti-5553 alloy was heat-treated at 900℃ (almost 50℃ above beta transus temperature)for one hour of soaking time followed by air quenching to achieve a fullyβphase *** that,Dynamic compression(DC)by Split Hopkinson Pressure Bar(SHPB)and Quasi-static compression(QSC)were performed at a strain rate of~10^3)/s and 10^(-3)/s,*** specimens were thoroughly examined by using different tools,such as an Optical microscope(OM),Scanning electron microscope(SEM),High-resolution transmission electron microscope(HRTEM),and Electron backscatter diffraction(EBSD)to get the reliable data for justification of logical *** is found that the dominating mode of deformation was dislocation slip along with twinning({332}<113>)to some extent in both of QSC and DC,but sliding&spalling of the grain boundary is observed more in the ***-induced phase transformation,i.e.,βtoα"andβtoω,took place in the grains saturated with dislocation slips,where the former transformation occurred simultaneously with{332}<113>twinning,whileβtoωtransformation was completed when a set of two adjacent(110)_(β)planes covered±1/6th of the total separation distance between two(next to each other)(111)_(β)planes,by equal but opposite shear in(111)_(β)direction,and it caused 3%shrinkage of two closed packed(110)_(β)planes after transformation.

关键词： High entropy alloys   Molecular dynamics   Strength   Ductility   Deformation   Mechanism  

摘要： We used molecular dynamics simulations to investigate the relationship between mechanical properties and deformation mechanisms in CoCrFeMnNi alloys having different compositions. According to deformation twinning activity, the deformation mechanisms in the different CoCrFeMnNi compositions under tensile loading can be classified into three major categories: easy-shear (ES), inter-locks (IL) and bulk hexagonal closed packed (hcp) transformation (BH). We found that the compositions with ES were more likely to rupture early because of the short and fragmented twins. The compositions following the IL pattern promoted the movement of interlocking stacking faults in the twin boundaries that could prolong tensile deformation. Moreover, BH could further increase ductility because the hcp transformation could absorb and dissipate the stacking faults. Experimental observations of immobile stacking-fault networks that impede dislocation motion and further provide preferred sites for the formation of the hcp phase were commonly found in the ES, IL and BH patterns. The calculated intrinsic stacking fault energies of CoCrFeMnNi and CoCrFeNi were consistent with the experimental measurements. The combination of high unstable stacking fault energy with the formation of the IL pattern results in high strength and high ductility in the CoCrFeMnNi HEA system.

关键词： Composite   Antibiotics   Surface chemistry   Clay minerals   Sorption  

摘要： Modification of biochar for efficient removal of antibiotics from water could be a valuable approach in the environmental applications. In this study, a brown seaweed (Sargassum crassifolium) was pyrolyzed at 500 degrees C and the obtained biochar (SWBC) was modified with zeolite through the slurry method maintaining the ratio at 1:5 (zeolite: biochar) (SWBC-Z). Batch adsorption experiments were conducted to evaluate the adsorption tendency of SWBC and SWBC-Z for the removal of ciprofloxacin (CPX) from water via pH edge, kinetics, isotherm and thermodynamic experiments. The highest adsorption was in the pH range of 6.5-8, supported by the electrostatic attractions and hydrogen bonding with zwitterionic CPX. Experimental kinetics data was well-fitted to the pseudo-second-order and Elovich models (R-2 of 0.992 and 0.976, respectively), while the Langmuir and Freundlich isotherm models best described the isotherm data (R-2 of 0.954 and 0.976, respectively). The maximum adsorption capacity of 93.65 mg g(-1) was recorded for the SWBC-Z. The models predicted chemisorption and physisorption interactions on the heterogenous biochar surface. Well-defined peaks of silanol groups in the FTIR spectrum of SWBC-Z and its electron microscopy confirmed the incorporation of zeolite minerals. Post adsorption FTIR analysis elucidated the changes in the surface functional groups of the SWBC-Z. Thermodynamic data revealed spontaneous and exothermic reaction between CPX and both the biochars. It was concluded that modification of pristine biochar with zeolite imparted greater surface area and additional active sites, which subsequently enhanced the overall CPX adsorption by the SWBC-Z.