高温抗折试验机功能的开发及应用

开发了高温抗折试验机重烧线变化率,烧后抗折强度及常温抗折强度3项检验功能,通过对设备控制程序的改进,可以按照设定的程序自动控制升温速率,推送样品,均匀加荷,自动化程度高,降低了操作人员的劳动强度,缩短了项目检验时间,试验结果准确可靠。     

可控制加荷速率耐压试验的开发与应用

为准确控制加荷速率,达到均匀加荷的目的,材料抗压试验机配置了电脑,开发了可控制整个耐压试验过程的控制程序,并且将压力试验和抗折试验统一到同一设备上,对于纤维制品等不易破碎的耐火材料,可以用定位移的方法,准确测量其耐压强度。对比试验表明,该方法测定耐压强度的变异系数仅为5．3％。     

蓄热室格子砖荷重软化温度试验方法

为准确测定蓄热室格子砖荷重软化温度，采用浸液称量法测量试样的体积，进而计算出加荷面积，测定其荷重软化温度。通过对比试验，此方法准确度高，操作简便，为改进蓄热室格子砖的质量提供准确的依据。     

极慢速加荷混凝土轴向拉伸试验研究

本文介绍极慢速加荷条件下混凝土轴向拉伸试验方法，它能测定混凝土受载时的特性曲线。各种加荷条件下，标号为Ｃ２５混凝土试样的抗拉强度，极限拉伸和弹性模量的测定结果显示：该方法稳定，可靠，能用于混凝土抗裂性能研究。     

常温拉伸应力松弛试验中的若干影响因素

以预应力钢材松弛试验为例,详细论述了影响常温拉伸应力松弛试验结果的四大因素:试验机精度,试样的加荷过程,试验温度,数据处理。指出了正确对产品进行松弛性能评估的几个要点。     

胶粘钢板在钢筋砼结构补强中的应用

通过模拟加荷试验方法，鉴定了其结构的可靠性，并为采用胶粘钢板法加固钢筋砼梁板结构提供了可靠的依据。叙述了胶粘钢板法加固砼梁板结构的操作工艺。     

包钢烧结配加918有机粘结剂工业试验

通过烧结矿配加９１８有机粘结剂工业试验，表明应用此项技术措施可获得增产，降燃耗，改善烧结矿质量的良好效果。     

烧结混合料配加酸性精粉的试验研究

通过配加酸性精粉的工业试验,研究了其对烧结矿强度及化学成分的影响,并探讨了配加酸性精粉制备高炉冶炼所需烧结矿的可行性。     

包钢烧结矿配加918有机粘结剂工业试验

通过烧结矿配加918有机粘结剂工业试验,表明应用此项技术措施可获得增产、降燃耗、改善烧结矿质量的良好效果.     

耐震钨丝特性及应用

研究了高钾掺杂钨丝、加钴掺杂钨丝和加铼掺杂钨丝的高温特性和耐震性能 ,进行了应用试验 ,指出了生产耐震灯泡时选用钨丝应注意的问题。     

早龄期冻结土压力与负温耦合作用的井壁混凝土性能

研究了早龄期冻结压力等荷载、负温及早龄期荷载和负温耦合作用对冻结竖井井壁C60混凝土抗压强度、氯离子扩散系数和声发射特征的影响,并通过扫描电镜分析其内部微裂缝.结果表明:早龄期荷载加载时间越早对混凝土28d抗压强度的影响越大,当外部荷载作用时间在3d以后且荷载水平在混凝土当天强度40%以内时,混凝土28d强度几乎不受影响;冻结井井帮负温环境会延缓井壁混凝土早期水化,防冻剂的加入利于加快混凝土水化和强度的发展;在早龄期荷载及负温耦合作用下,混凝土28d抗压强度降低明显,氯离子扩散系数大大增加,混凝土的渗透性由"中"变为"高",内部产生了缺陷和微裂缝导致声发射"活跃阶段"提前,且混凝土呈现明显的塑性变形.      

A REVIEW OF PARAMETERS INFLUENCING SOME MECHANICAL PROPERTIES OF TUNGSTEN CARBIDE–COBALT ALLOYS

Abstract

The paper reviews experimental results relating to the influence of composition, structure, and testing conditions on the hardness, compressive strength, and transverse rupture strength of sintered tungsten carbide–cobalt alloys.     

Unidirectionally solidified Ti−TiB and Ti−Ti5Si3 eutectic composites

Induction melting and electron beam melting techniques were employed in the production of unidirectionally solidified eutectic composites of Ti-1.7 wt pct B and Ti-8.5 wt pct Si. The grown eutectics were reinforced by 7.7 volume pct of TiB fibers and 31 volume pct of Ti₅Si₃ fibers respectively. Controlled dendritic solidification of a hypereutectic composition of Ti-12 wt pct Si was also accomplished. Tensile, compressive, creep, and stress rupture specimens were cut from the eutectic composites and tested with reinforcing fibers parallel to the load axis. Ti?TiB eutectic was found to have less than the critical volume fraction of fibers necessary for reinforcement, while Ti?Ti₅Si₃ composite attained a compressive yield strength of 275,000 psi and a compressive Young's modulus of 30×10⁸ psi after heat treatment. The 500 and 4000 hr stress rupture properties of Ti?Si eutectic were superior to commercial titanium alloys at 1000° and 1200°F. The minimum creep rate of Ti?Ti₅Si₃ eutectic composite was lower than all other titanium alloys at 1000°F. Tensile, compressive, and creep properties of the Ti-8.5 wt pct Si eutectic are discussed in terms of the current theories of composite behavior.     

Larson–Miller Failure Modeling of Aluminum in Fire

This article presents a modeling approach based on the Larson–Miller parameter (LMP) for creep rupture to predict failure of aluminum in fire. The modified Larson–Miller model can predict time-dependent tensile rupture or compressive buckling of aluminum plate under combined loading and one-sided heating by fire. The model applies the LMP to determine the failure time and failure temperature of aluminum exposed to fire. Fire structural tests were performed on an aluminum alloy (5083-H116) subjected to different load levels and heat flux conditions (with maximum temperatures of 473 to 688 K (200 to 415 °C)) to validate the Larson–Miller modeling approach. The tests reveal that the Larson–Miller model can accurately predict tensile and compressive failure of aluminum plates (with and without surface insulation) in fire in terms of critical temperature and time.     

Shear Failure of Pultruded Fiber-Reinforced Polymer Composites under Axial Compression

When structural elements are subjected to compressive loads, the shear forces and stresses induced by second-order effects may lead to shear failure prior to compressive failure. This is particularly likely to occur in the case of pultruded glass fiber-reinforced polymer profiles, which normally exhibit low shear strength in relation to compressive strength. This paper analyzes the effects of initial imperfection, slenderness, shear-to-compressive strength ratio, shear coefficient, and type of shear failure criterion on ultimate load and failure mode (shear or compressive failure). A formulation for predicting ultimate load based on shear failure and second-order deformation is proposed. The results obtained compare well with similar results obtained using other methods and experimental data available in literature. The proposed method is based strictly on mechanics and thus requires no fitting to experimental data.     

链箅机-回转窑工艺生产碱性球团矿工业试验

摘要：在实验室研究的基础上,开展了链箅机-回转窑工艺生产碱性球团矿工业试验。结果表明,生产二元碱度（CaO/SiO2）为1.0左右的球团矿时,与酸性球团矿生产工艺相比,将预热段温度提高30℃左右,回转窑窑头温度降低10℃左右,链箅机的机速降低0.3m/min左右,成品球团矿的抗压强度可达到或稍高于酸性球团矿。碱性球团的还原膨胀率受球团矿抗压强度以及碱度影响较大,当球团矿抗压强度相当于（或大于）酸性球团矿,且碱度大于1.0时,其还原膨胀率才能低于或接近酸性球团矿。     

Design and Fabrication of FRP Grids for Aerospace and Civil Engineering Applications

This paper presents the results of experimental and analytical studies of the performance of composite grids as well as fiber-reinforced polymer (FRP) grid reinforced concrete columns. FRP grids and FRP grid confined concrete cylinders were instrumented and tested under uniaxial compressive loading. Test variables included types of composite materials and the spacing of composite circular ribs. It is shown that the proposed FRP grids can be constructed by filament winding, the process can be automated, and the manufacturing cost can be reduced. Results show that the proposed FRP grids have substantial ultimate load that make them attractive for use in aerospace applications, and that confinement of concrete by FRP grids can significantly enhance the strength, ductility, and energy absorption capacity of concrete as compared to steel confined concrete. Equations to predict the compressive strength and failure strain were developed. Comparisons between the experimental and analytical results indicate that the proposed models provide satisfactory predictions of ultimate compressive strength and failure strain.     

烧结矿高温抗压强度研究

 采用高温可调气氛抗压实验机对烧结矿高温抗压强度的变化规律进行了实验研究,研究发现：烧结矿还原前的抗压强度随温度的升高而逐渐降低,而还原后其抗压强度随温度和还原程度的变化出现了一定程度的波动,并与自身气孔率存在一定的线性关系。结合实验研究的结果对冶炼过程中烧结矿在冷态和热态下的破损机理分别进行了剖析。     

球团矿氧化焙烧过程中的热强度研究

本研究的主要目的是了解球团矿在氧化焙烧过程中的抗压强度变化规律，为工艺可行性判断及参数优化提供理论依据．通过不同温度的系列焙烧试验得到了不同配料的球团矿并测得了常温单球抗压强度．使用一台可调气氛高温抗压试验机研究了相应球团矿在氧化焙烧过程中的强度变化规律．研究发现，球团矿在焙烧过程中，在一个特定温度tmax下强度大幅度下降．如果tmax高于必要的焙烧温度tmax，竖炉焙烧工艺是可行的．反之则是不可行的．