Phase and Microstructural Characterization of Iron Ore Pellet and their Relation with Cold Crushing Strength Test

In the production of the pellets, phase identification for specific sintering condition is of prime importance in understanding the basis for the production and the required properties. The application of a methodology involving optical and scanning electron microscope equipped with an EBSD opened a broad possibility to establish a base for the relationship between heat-treated pellet microstructural features and cold crushing strength. The first results from the conjoined application of these techniques show that the cold crushing strength of the pellet increase with the decrease of porosity, the appearance of the fayalite, as well as the presence of magnetite-unoxidized.     

Experimental and numerical crashworthiness investigation of empty and foam-filled end-capped conical tubes

Foam-filled thin-wall structures exhibit significant advantages in light weight and high energy absorption. They have been widely applied in automotive, aerospace, transportation and defense industries. Quasi-static tests were done to investigate the crash behavior of the empty and polyurethane foam-filled end-capped conical tubes. Non-linear dynamic finite element analyses were carried out to simulate the quasi-static tests. The predicted numerical crushing force and fold pattern were found to be in good agreement with the experimental results. The energy absorption capacities of the filled tubes were compared with the empty end-capped conical tubes. The results showed that the energy absorption capability of foam-filled tube is somewhat higher than that of the combined effect of the empty tube and the foam alone. Finally, the crash performance of the empty and foam filled conical and cylindrical tubes were compared. Results from this study can assist aerospace industry to design sounding rocket carrier payload based on foam-filled conical tubes.     

铝土矿球磨-分级过程建模与仿真

建立铝土矿磨矿分级过程模型。对研究流程的行为和实现优化控制具有重要意义。本文通过试验研究了铝土矿的破碎特性．提出分段线性化的方法准确地描述铝土矿破碎速率随时间变化且不同粒级变化速率不同的情况。在此基础上求得了铝土矿的破碎分布函数：依据实际生产数据估算了物料的停留时间．建立了连续磨矿破碎速率的软测量模型。从而建立了铝土矿连续球磨总体平衡模型：基于罗辛-拉穆勒曲线和混杂曲线．并考虑不同生产条件对分级效果的影响。建立了螺旋分级过程的分级效率模型：基于序贯模块法的整个磨矿分级流程仿真结果证明了模型的有效性。     

铸铁段用于氧硫铅锌混合矿磨矿工艺的试验研究

从磨矿工艺入手,针对矿石的特殊力学性质采用特殊的磨矿新工艺,具体就是采用介质尺寸精确及选择破碎作用强的选择性磨矿新工艺,降低过磨过粉碎,降低磨矿产品中-500目粒级的含量,使磨矿产品尽量满足选矿的条件,有利于矿石分选。结合会泽采选厂工业试验情况进行实例分析,从而验证上述结论的合理性。     

高能球磨对碳纳米管增强铝基烧结含油轴承性能的影响

采用粉末冶金工艺制备铝粉、球磨铝粉和球磨混合粉末(添加2wt％ MWCNTs的铝粉)烧结含油轴承,测定烧结样品的性能,并研究高能球磨对粉末性能及样品性能的影响规律和机理.结果表明,球磨后粉末颗粒尺寸减小并呈薄片状或层状,MWCNTs被剪断分散后包裹在铝粉颗粒中.粉末球磨易于原子扩散促进烧结颈的形成,提高烧结样品压溃强度...     

废铅酸蓄电池铅再生技术现状及进展

对废旧铅酸蓄电池的物质组成特性进行分析,介绍了破碎分选技术和铅膏回收利用技术的生产应用和研究进展,对比了各工艺的优缺点,分析了铅精矿搭配铅膏的氧化还原熔池熔炼法的特点、优势,阐明该工艺可实现高温熔池集约脱硫,是低碳、环保、高效的再生铅生产工艺.     

Modelling of the Behaviour of Aramid Folded Cores Up to Global Crushing

Abstract: This study presents the basic ingredients needed to model the out‐of‐plane compression behaviour of a folded core up to the global peak load. This core is made of an aramid paper. The proposed approach is both experimental and numerical and handles the problem at different scales: fibre, paper and core scales. To have a good representation of the physics, two key points are essential. The first is the mechanical behaviour of the paper. The aramid paper can be modelled as a laminate composite. An experimental study of the paper behaviour in bending has been conducted to build a damage model for the paper. The second key point concerns the geometrical defects of the folded core. The defects, arising from the manufacturing process, are built by simulation of the folding process. The macroscopic behaviour of the core under out‐of‐plane compression loading is shown to be very sensitive to these defects. The results of a simulated crushing test are compared to experimental ones. A good agreement is shown.     

空心和泡沫填充且端部封闭锥形筒的耐撞性试验和数值分析

泡沫填充的薄壁结构的优点是质量轻和高吸能性能,广泛地应用于汽车、航空、运输和防护等行业。采用拟静力试验,分析空心和泡沫填充的端部封闭的锥形筒的耐撞性能,采用非线性动力有限元模拟拟静力试验,数值分析的抗冲撞力与试验数据很吻合。对未填充的锥形筒和填充的锥形筒的耗能能力进行对比,结果显示,泡沫填充的锥形筒的耗能能力比较好。最后,比较了空心、泡沫填充端部封闭的锥形筒和圆筒的耐撞性。     

道路工程中水泥稳定碎石的再生利用

分析了旧水泥稳定碎石作为再生集料的特性及其对新生成混合料的影响,从理论及实践方面研究了将旧水泥稳定碎石作为再生集料用于新建道路、旧路改造的可行性,以期促进再生集料在今后道路工程中的推广应用。     

颗粒破碎对砂土剪切性质影响的离散单元研究

采用离散单元方法,建立了圆形颗粒、不破碎非圆形颗粒和破碎非圆形颗粒的数值试验模型,进行了砂土的双轴剪切试验,研究了颗粒破碎现象对砂土物理力学性质的影响,分析了颗粒破碎和颗粒形状对试样强度的影响以及围压对颗粒破碎性质的影响。研究结果表明：颗粒破碎现象严重影响砂土的峰值强度以及体积应变性质,并且低围压下颗粒形状对强度影响大于颗粒破碎,随着围压增大,颗粒破碎的影响逐渐增强;围压影响颗粒破碎发生的速率和最终的破碎率;由对颗粒破碎的位置和试样内位移场的追踪可得到颗粒破碎的细观演化规律及破碎带的分布范围,破碎带分布范围与围压有关。