Damage and failure characterization of 7075 aluminum alloy hot stamping

7000 series high strength aluminum alloys are increasingly used in manufacturing automobile body parts to meet the more stringent demands for automobile lightweight. Hot stamping of 7000 series high strength aluminum alloys is a complex thermal-mechanical coupling process and precise simulation is needed to predict material fracture. To obtain damage model of 7075 aluminum alloy in hot stamping, five different stress triaxiality specimens were designed. The fracture strain, critical strain and average stress triaxiality of different specimens were obtained by the hybrid finite element simulation and experiment (FE-EXP) method. GISSMO model of 7075 aluminum alloy at 400 °C was established. Compared with the experimental results of U-shaped part hot stamping under different lubrication conditions, the calibrated GISSMO model was demonstrated to predict the damage behavior of 7075 aluminum alloy during high temperature deformation accurately.

     

利用分形理论评价潜山裂缝型油藏油井产量变化特征

以渤海海域JZ25-1S油田为例,利用分形理论评价了潜山裂缝型油藏油井产量的时间序列变化特征,建立了分形维数与产出流体类型、生产井型及不同工作制度的关系,结果表明:油井产量具有很好的分形特征,分形维数与产出流体类型基本无关;同一井组内,水平井生产的分形维数高于定向井;同一口井不同工作制度生产对应油井产量的分形维数不同,随着油嘴或泵频率逐步增大,对应的分形维数逐步减小。通过研究油井产量的分形维数可以用间接表征裂缝型油藏储层裂缝发育程度,而且油井产量的分形维数越大,储层的裂缝越发育,油井采油指数递减幅度也越小。     

提高烧结机机头电除尘器效率的技术改造

本文主要介绍了唐钢炼铁厂为提高烧结机头电除尘器除尘效率所进行的技术改造。通过对除尘器安装声波清灰器,对进出口管道、电场内部进行简单改良,对三、四电场供电系统改装高压脉冲电源MPS等措施,使除尘效率由原来的95％提高到98％以上,烟尘排放浓度由原来的97mg／m3降低到50mg／m3以下,同时节电约60％,节能减排效果显著。     

地源热泵用高导热PE管的研究

通过在PE管材中添加导热母粒,制备了具有高导热系数的PE管。实验结果表明：导热系数较普通塑料管提高了75%,达到0.7 W/（m.K）;其它各项力学性能也均符合同规格PE给水管材标准的要求;管材满足地源热泵系统工程技术规范（GB 50366-2009）的施工要求;在同等条件下,当打井费与管材费用比大于10.93时,地埋管选用高导管比较实惠;水源热泵系统中,高导热管总造价比普通PE管造价降低16%以上。