多晶体材料微结构仿真与数值计算

根据Laguerre图几何结构和拓扑形貌上的特征,同时引入多晶体材料微观组织结构的各向异性行为,实现了多种不同类型多晶体材料微观组织结构的表征。通过集成自主开发的Laguerre图构造程序和对商业有限元软件ABAQUS二次开发的脚本程序,开发了一套适用于材料微结构数值模拟的基础性平台软件VirtualTPS。最后,利用软件对多晶体材料微结构代表性体积单元的细观力学响应进行了数值计算与分析。     

二维复合材料微结构的力学响应计算

复合材料的力学响应数值计算对于多元多向异质体材料微结构的“性能导向型”设计、材料微结构失效的评估与预测具有重要的意义。利用自主开发的材料微观组织结构仿真软件ProDesign构造出二维复合材料微结构的代表性体积单元,通过C语言、Python脚本混合编程的方式,实现对商业有限元软件ABAQUS前处理的二次开发,使之用于复合材料微结构几何模型的建立、材料属性与晶粒取向的赋值、边界条件的定义以及有限元网格的划分,从而有效地实现二维复合材料微结构的细观应力响应计算。     

直接氧化法制备Al2O3/Al陶瓷基复合材料研究

研究了采用直接氧法制备Ａｌ２Ｏ３／Ａｌ复合材料,实验分析了镁元素对铝氧化的决定因素和硅对氧化速度的影响,通过Ｘ－线衍射对烧结材料进行物相分析,光镜观察烧结材料的结构是三维联通的三氧化二铝瘊多晶体中分布了三维联通的网状的残余铝合金。     

放电等离子烧结制备TiC/7075铝基复合材料实验研究

在实验中运用放电等离子烧结技术制备TiC/7075铝基复合材料,并分析了不同TiC含量的TiC/7075烧结块体的组织结构和力学性能。采用球磨工艺混合7075合金粉和TiC粉末,在500℃下烧结制备TiC/7075铝基复合材料;利用XRD、SEM、EDS、HVS-1000分析烧结块体的物相、微观组织、维氏硬度。研究发现,烧结制备的TiC/7075铝基复合材料中只有Al和TiC相,没有新相形成; TiC在基体材料中分布均匀,制备的烧结块体致密度高达98%,其维氏硬度随着TiC含量的增加而增加。     

面向在轨测量任务的伴飞机器人三维仿真系统

为了避免空间伴飞机器人末端探测器与自身载体或者与待测航天器之间发生碰撞,在实际进行在轨测量之前,需要对其末端探测器轨迹规划方法进行充分的三维图形仿真.针对现有空间机器人地面仿真系统不能可视化的问题,设计了一种基于虚拟现实技术的三维仿真系统.首先,建立了基于Open Inventor的空间机器人三维实体几何模型,并构建反应空间机器人逻辑位置的三维仿真场景.然后,基于数据传输技术和构建的三维仿真场景建立了空间机器人可视化三维仿真系统.最后,建立空间机器人运动学模型并对空间机器人末端执行器跟踪的圆弧轨迹进行规划.仿真结果表明,利用该系统可直观得到空间机器人的运动过程以及空间机器人载体的运动特性,有利于空间机器人的轨迹规划和控制算法的仿真研究,可避免因不当轨迹规划而造成空间机器人发生碰撞.     

人体髋部组织几何建模程序实现

为了设计针对人体组织建模和分析的仿真软件,利用Visual C++语言,以Visual Studio2010为开发工具在Windows平台上设计开发一个人体组织三维建模软件,它既可以单独使用,也可以作为虚拟手术系统的子模块。该软件主要包括医学图像分割和三维重建模块,并能够实现三维模型的可视化显示。通过该软件对人体髋关节肌肉、股骨和髋骨进行分割及三维重建,所生成的三维几何模型能够合理的表达出髋部组织的结构信息。     

异质材料零件切片数据插补研究

现代制造业对产品性能要求越来越高,因此零件成型精度与打印质量成为三维打印技术研究的关键问题. 本文基于空间微四面体异质材料零件建模,提出了异质材料切片数据插补算法,编写程序并仿真实验结果. 在课题组研发的三维打印成型系统上进行异质材料零件的成型实验,验证了所提算法的正确性. 该方法实现了异质材料零件色彩连续渐变,提高了异质材料零件成型精度和打印质量.     

Al_2O_3·TiO_2-MgO·2TiO_2复合物系陶瓷的结构与性能

作者用 X 射线衍射仪法定量分析了 Al_2O_3-MgO·2T1O_2复合物系在烧结过程中的物相变化及烧结体的物相组成和晶格参数。探讨了(Al_(2(1-x))Mg_xTi_(1+x)O_5型固溶体的形成机制。通过扫描电镜和偏光显微镜观测烧结体的微观组织,结合弯曲强度及热膨胀、收缩性能,讨论了烧结体组成、结构与性能之间的相互关系。     

矿渣基地质聚合物干粉材料的性能与反应机理

以矿渣和水玻璃粉体为原料制备地质聚合物干粉材料,研究了水灰比对地质聚合物凝结时间和强度的影响,通过XRD、SEM和FTIR等分析技术系统研究了水玻璃粉体制备矿渣基地质聚合物的物相组成、微观结构和分子结构,分析了水玻璃粉体激发矿渣的反应机理。结果显示,水灰比从0.30增加到0.38,干粉材料的初凝时间从10min增加到22min,终凝时间从13min增加到26min,抗压强度从82.9MPa减少到63.4MPa。微观分析表明水玻璃粉体与矿渣的反应以地质聚合反应为主,矿渣基地质聚合物为无定形的网络结构。     

三维可视化技术在含气砂岩储层预测中的应用

三维可视化技术是一种全三维地震资料解释方法,有效地将地质知识应用于地震解释的先进手段,它可以提高解释人员从三维地震中快速获取地质信息的能力。应用帕拉戴姆公司的VoxelGeo三维可视化解释技术,在三维数据体内部直接工作,对研究区块的构造、地层和振幅特征进行综合研究,通过三维快速扫描,调节透明度,进而识别出异常体。在此基础上进行顶底雕刻,获得砂体的厚度变化,从而揭示河流相砂体储集体的空间展布规律。该方法在研究区域的应用效果比较明显。     

Microstructure and mechanical properties of Al_3Ti-based alloys in Al-Ti-Mo-X quaternary systems

A part of Al-Ti-Mo-Cr quaternary phase diagram is constructed for the microstructure control of D022-Al3Ti or its derivative, L12-(Al,Cr)3Ti, -based alloys. It was found that quaternary bcc phase equilibrates with either D022-Al3Ti or L12-(Al,Cr)3Ti, or both, exist in large compositional areas. The mechanical properties is strongly affected by precipitates appearing, and presumably alloy microstructures.     

Three dimensional microstructure and image-based simulation of a fly ash/al syntactic foam using X-ray micro-computed tomography

An aluminum matrix syntactic foam, incorporated with hollow-structured fly ash particles, was fabricated by pressure infiltration technique. X-ray micro-computed tomography was used to characterize its heterogeneous microstructure three dimensionally (3D). The quantification of some microstructure features, such as content and size distribution of hollow fly ash particles, was acquired in 3D. The tomographic data were exploited as a rapid method to generate a microstructurally accurate and robust 3D meshed model. The thermal transport behavior has been modeled using a commercial finite-element code to conduct steady state analyses. Simulation of the thermal conductivity showed good correlation with experimental result.     

Effects of ultrasonic field on microstructures and properties of semi-solid AZ91D magnesium alloy

The microstructure distribution rule of semi-solid AZ91D alloy treated by ultrasonic was researched, and mechanical properies of specimens before and after ultrasonic treatment were investigated further.Semi-solid AZ91D melt specimens were processed by ultrasonic under different powers, and its microstructures and mechanical properties at different sampling points in specimens were obtained. The experimental results show that the microstructure of AZ91D alloy at different sampling points under the same ultrasonic power is different in grain size and shape, and there is also great difference among their microstructures at the same sampling point under different ultrasonic powers. AZ91D alloy treated by ultrasonic can obtain increment in both tensile strength and plasticity. Under same ultrasonic power, mechanical properties of specimen at different sampling points have obvious difference, and regularity for change of mechanical properties everywhere is similar to regularity for change of grain size and shape everywhere.     

亚微米光栅微结构光学特性研究

提出了一种新型的亚微米光栅微结构,研究了其光谱共振特性．给出了该结构的反射光谱及光谱带宽表达式,用矢量衍射的方法对比分析了该结构与亚波长光栅的共振、光谱带宽及线形改良的规律．研究表明：微结构的共振及光谱带宽由等效光栅强度和导波的位相光谱移相速率决定,前者的物理意义为耦合到微结构内一级衍射光的能量;提出的微结构与亚波长光栅有相似的共振特性,但带宽明显增大;微结构的光栅调制度并不影响其有无共振特性,但光谱带宽及共振面积却随着调制度的增加而增大;经设计微结构将有优良的窄带及宽带滤波功能,而后者可使之呈现肉眼可见的新型彩色光变效果,可以应用于防伪领域．     

4种表面微观结构推力轴承的承载特性研究

设计了凹圆、凸圆、凹条、凸条4种典型的表面微观结构,并采用有限元方法对这4种表面微观结构推力轴承在液体中的承载特性进行了研究,分析了各表面微观结构轴承在不同轴承间隙、转速和液膜黏度等工况条件下对承载力的影响规律。结果表明:4种表面微观结构轴承在液体润滑条件下均能产生承载力,不同微观结构轴承在相同工况条件下承载力大小不同,推力轴承的承载力随轴承间隙的增大而逐渐降低,随轴承角速度的增大而增大,随润滑液液膜黏度的增加而增大;凸形微观结构推力轴承的承载力受轴承间隙、转速和液膜黏度的影响较大,而凹形微观结构推力轴承的承载力受以上因素的影响较小。     

EA4T钢表面激光熔覆Fe-Cr-Ni涂层的组织与性能

通过激光熔覆技术对损伤车轴EA4T钢表面进行修复,利用光学显微镜、扫描电镜和X线衍射方法分析修复层的显微组织结构,利用万能拉伸试验机和应力测试仪测试修复层和基体的结合性能及残余应力。研究结果表明:修复层显微组织主要由γ-Fe固溶体、BNi₃、M₇C₃和Fe₃C组成,热影响区为上贝氏体和呈网状分布的铁素体组织,修复层和基体的结合区主要由平面晶、柱状晶和树枝晶组成,修复层顶部区域其组织主要以交叉树枝晶为主;激光熔覆后的EA4T钢的抗拉强度升高,但屈服强度和常温U型缺口冲击性能降低;整个修复层中残余应力较大,呈拉应力状态分布,而基体区域呈压应力状态分布。     

Microstructure evolution and precipitation behavior of low carbon steel hot strips produced by CSP

The microstructures of low carbon steel before, during and after rolling deformation of each stand were observed using optical microscope. The result showed that the microstructures were very fine after six passes rolling deformation. The effect of the first stand reduction on microstructure refinement was very distinct. During the rolling process, with the increase of the accumulated strain, the microstructures would further refine, and the density of dislocation would increase at the same time. In continuous casting thin slabs and each finishing stand, lots of observed precipitates were mainly A12O3 and MnS along the grain boundaries or in grains,which played an important role in the mechanical properties of the hot strips of low carbon steel produced by CSP (compact strip production) technology.     

Preparation of material surface structure similar to hydrophobic structure of lotus leaf

Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol） （PVA） and polystyrene （PS） moulds of the mastoid microstructure on lotus leaf surface were prepared respectively by the nano/micro replication technology. And poly（dimethylsiloxane） （PDMS） replicas with the mastoid-like microstructure were prepared from these two kinds of polymer moulds. Scanning electronic microscope （SEM） was employed to investigate the morphology and microstructures on moulds and replicas. Both the static and dynamic contact angles between water droplet and PDMS replicas＇ surface were also measured. As a result, similar microstructure can be observed clearly on the surface of PDMS replicas and the static contact angle on PDMS replicas was enhanced dramatically by the existence of these microstructures.     

Heat treatment behavior of can-forged titanium aluminide alloy in ( α + γ ) region

The effect of initial microstructures on the heat treatment behavior of can-forged titanium aluminide alloy has been studied. Optical microscopy and EDX analyses results show that different initial microstructures, including difference in dislocation density, phase distribution and morphology, have inherent effects on the final heat treatment microstructure although at the same heat treatment temperature. An almost full lamellar (NFL) microstructure with an average α ₂/γ colony size of 20 μm was obtained through adjusting initial microstructure. Project supported by the “863” High Tech Program and the National Natural Science Foundation of China Synopsis of the first author Liu Yong, Doctoral student, born in April 1973. Specializing in powder metallurgy of ceramics, intermetallics and metal: 1) Ca/P based bioceramics; 2) TiAl based intermetallics; 3) Fe, Cu materials.     

铸造-热变形Nd-Fe-B永磁合金显微组织及性能的研究

对铸造NdFeB磁体进行了不同变形温度、不同变形量的热压及压后热处理的实验.研究了不同工艺下磁体的显微组织以及与磁性能的关系.结果表明,NdFeB永磁合金的磁性能和磁体的微观组织有密切关系.铸态组织对制造铸造-热压NdFeB永磁材料具有重要的影响,最终组织晶粒细小、均匀,主相被富Nd相薄层包围,晶界平直,高C轴取向,可以获得高磁性所要求的微观组织.