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Element Analysis of Instrumented Sharp Indentations into Pressure-sensitive Materials

Minh-Quy LE , Seock-Sam KIM

材料科学技术(英文)

Finite element analysis was carried out to investigate the conical indentation response of elastic-plastic solids within the framework of the hydrostatic pressure dependence and the power law strain hardening. A large number of 40 different combinations of elasto-plastic properties with n ranging from 0 to 0.5 and σy/E ranging from 0.0014 to 0.03 were used in the computations. The loading curvature C and the average contact pressure pave were considered within the concept of representative strains and the dimensional analysis. Dimensionless functions associated with these two parameters were formulated for each studied value of the pressure sensitivity. The results for pressure sensitive materials lie between those for Von Mises materials and the elastic model.

关键词: Finite element analysis , null , null , null

Finite Element Analysis of Ceramic Coatings under Spherical Indentation with Metallic Interlayer: Part I Uncracked Coatings

Minh-Quy LE , Seock-Sam KIM

材料科学技术(英文)

Spherical indentation of ceramic coatings with metallic interlayer was performed by means of axisymmetric finite element analysis (FEA). Two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel were considered. Various combinations of indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. The effects of the interlayer, the coating and the substrate on the indentation behavior, such as the radial stress distribution along the coating surface as well as the coating interface, and the plastic deformation zone evolution in the substrate were investigated in connection with the above mentioned ratios. The coating cracking dominant modes were also discussed within the context of the peak tensile stresses on the coating surface and on the coating interface.

关键词: Finite element analysis , null , null , null

Effect of Seed Sizes on Growth of Large Synthetic Diamond Crystals

Chuanyi ZANG , Rui LI , Hongan MA

材料科学技术(英文)

For the growth of large synthetic diamond crystals by temperature gradient method (TGM), the grit sizes of seed crystals have great effects on the growth rate and quality of large grown crystals. Because of the limited area of seed surfaces, the maximum diffusion flux of carbon source, which could be absorbed by the seed, is related to the seed size. And with increasing the seed sizes, the growth rates also increase markedly. However, the seed sizes should be lower than a certain value, which determines the crystal quality directly. For example, with NiMnCo alloy as the metal solvent, when the seed size increases from 0.5 to 1.8 mm, the growth rate increases greatly from about 1.1 to 3.2 mg/h; when the size is beyond 2.0 mm, more and more metal inclusions would be incorporated into the grown crystals, and the crystal quality is destroyed heavily. Finite element analysis (FEA) shows that, due to the special assembly of growth cell, the diffusion of carbon source in the metal solvent is very inhomogeneous, which could be substantiated directly by the appearances and shapes of large grown crystals and the remains of carbon source. And this inhomogeneous diffusion of carbon source would be very harmful to the growth of large diamond crystals, especially when large-size seed crystals are used.

关键词: Temperature gradient method , null , null , null

Modeling of Microimprinting of Bulk Metallic Glasses

Ming CHENG

材料科学技术(英文)

A finite element analysis (FEA) model has been developed to analyze microimprinting of bulk metallic glasses (BMG) near the glass transition temperature (Tg). The results reveal an approximately universal imprinting response for BMG, independent of surface feature length scale. The scale-independent nature of BMG imprinting derives from the flow characteristics of BMG in the temperature range above Tg. It also shows that the lubrication condition has a mild influence on BMG imprinting in the temperature range above Tg.

关键词: Bulk metallic glasses , metallic , glasses , Finite , element , ana

Numerical Simulation of Welding Deformation for Hull Superstructure Steel Based on the Finite Element Analysis

Liming LIU , Guoli LIANG , Yujun LIU , Zheng ZHAN

材料科学技术(英文)

Using finite analysis element software, the transient displacement field of automatic submerged arc welding is established. It was also considered that the thermal physical properties changes were depended on the temperature and the heat loss on the surface. At the same time, it analyzed the influence of the deformation and stress, which generated in the plate butt-welding process, to the superstructure steel welding deformation. The result showed that the deformation and stress generated in the steel plate butt-welding process are considered to be the main factors to influence the welding deformation of superstructure steel. It found the effective ways to reduce the welding deformation of the hull superstructure steel is to relieve the butt-welding deformation and release butt-welding stress before welding the hull superstructure steel.

关键词: Hull superstructure steel , null , null

基于Pro/Mechanica的IPM散热分析及优化

甘屹 , 王兆凯 , 孙福佳 , 何燕

功能材料与器件学报

建立了三菱IPM的简化热模型,利用有限元分析方法,运用Pro/Mechanica为对其工作温度场进行了分析.针对芯片自身结温超过芯片的最大可承受温度的情况,对IPM的散热性能提出了优化方案,采用针形散热器以实现其外表热量的快速散发.并提出一种新型的封装形式,即用塑封树脂和铝合金进行混合封装.通过热分析表明,该封装对于IPM芯片散热有着明显的作用.

关键词: IPM , 有限元 , 热分析 , Pro/Mechanica , 散热 , 封装

三维浅交弯联机织复合材料弯曲性能的有限元分析

冯古雨 , 曹海建 , 钱坤

宇航材料工艺 doi:10.3969/j.issn.1007-2330.2015.06.005

借助Pro/Engineer绘图软件,建立三维浅交弯联机织复合材料及弯曲压头的结构模型,进行弯曲性能研究.借助ANSYS Workbench有限元软件,探究复合材料在5mm弯曲位移载荷作用下纤维、树脂和复合材料的应力、应变分布,并对复合材料的破坏模式进行预测.结果表明:三维浅交弯联机织复合材料在弯曲载荷的作用下,试样与上、下压头接触处最容易发生弯曲破坏;三维浅交弯联机织复合材料在承载弯曲载荷时,增强体纤维起到主要承载作用,树脂基体起次要承载作用;在5 mm的弯曲载荷作用下,复合材料的破坏模式主要是树脂的破碎.

关键词: 有限元分析 , 三维机织复合材料 , 浅交弯联 , 弯曲载荷

单纤维复合材料体系界面性能的实验研究与数值分析

郝建伟 , 肇研 , 罗云烽 , 王琰 , 陈达

新型炭材料 doi:10.1016/S1872-5805(14)60133-5

针对微脱黏测试建立细观力学模型,通过模拟纤维从树脂微滴中的拔出过程评价炭纤维增强双马树脂基复合材料的界面性能。为了深入理解湿热环境对复合材料界面性能的影响,通过微脱黏方法测试不同湿热环境条件下炭纤维增强双马树脂基复合材料的界面剪切强度。结果表明,湿热老化会导致界面剪切强度下降,吸湿达到饱和后界面剪切强度也会趋于稳定。在实验的基础上,基于内聚力界面单元建立脱黏过程的数值模型以表征复合材料的界面特性,评价实验参数与界面特性的关系。微脱黏模型还为宏观力学性能的数值分析提供包括界面相在内的必要的实验参数。微脱黏测试的有限元分析表明刮刀夹持位置、热残余应力以及湿热条件均会对界面应力分布产生影响。

关键词: 微脱黏 , 炭纤维 , 湿热效应 , 界面剪切强度 , 有限元分析

热浸渗铝制备Fe-Al合金层温度-应力场有限元分析

黄敦伟 , 侯新瑞 , 胡爱萍

表面技术

目的 分析渗层厚度、加热温度及加热时间对渗层温度场-应力场的影响规律.方法 利用ANSYS有限元软件对热浸处理制备Fe-Al合金层进行建模,计算铝的焓值,采用间接耦合法计算渗层应力.结果 沿X轴方向,温度变化趋势大体上一致,均表现出上升的趋势,局部出现温度突变现象;渗层最高温度(935.528℃)与加热温度(950℃)相差15℃,温度损失约1.52%;不同厚度下温度的变化趋势均为递减,当厚度为200μm时,温度递减的趋势平稳,未出现峰值;随着渗层厚度的增加,应力值先增加,后减小,而后再增加.结论 考虑应力、厚度对渗层性能的影响因素,渗层最佳厚度应为200μm.

关键词: 有限元分析 , 热浸处理 , Fe-Al合金层 , 温度场 , 应力场

复合材料层合板斜接式挖补修理稳定性分析

卢俊文 , 王倩营 , 朱新宇 , 张成雷

宇航材料工艺

对复合材料层合板挖补修理模型进行了参数化的有限元计算,分析了挖补修理结构失稳载荷与挖补角、胶层厚度以及铺层方式之间的关系,得到了最优挖补修理模型.结果表明,异种材料补片会显著提高挖补修理结构的稳定性,在一定范围内,减小胶层也会改善挖补修理结构的稳定性.当胶层厚度在0.15~0.25 mm变化时,随着胶层厚度减小,挖补修理结构的稳定性增强;当铺层方式为[03/±45/±45/90]s时,挖补修理结构稳定性最强.

关键词: 挖补修理 , 线性屈曲 , 异种材料补片 , 有限元分析

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