基于ANSYS/LS-DYNA的磨料冲击行为分析

采用实验与有限元模拟相结合的方法研究了磨料形状和粒径对材料冲蚀磨损性能的影响.采用linear-elastic-isotropic模型作为靶材的本构模型,运用ANSYS/LS-DYNA的三维显式动力分析模型建立了棕刚玉磨料冲蚀高强耐火浇注料的有限元模型,运用求解器对冲蚀过程中的磨料冲击行为进行了计算.结果表明:单个六棱柱体磨料颗粒对靶材中心点的von mises应力最大值为球体磨料的4倍左右,磨料形状对冲蚀磨损有很大影响;随着磨料粒径的增大,靶材中心点的von mises应力最大值急剧增加;110 ℃烘后高强耐火浇注料的冲蚀磨损率随着磨料粒径的增加而增加,磨料粒径的增加对1100 ℃烧后高强耐火浇注料的冲蚀磨损率影响不大.     

CaO-Al2O3-SiO2系统微晶玻璃的冲蚀磨损研究

CaO-Al2O3-SiO2系统微晶玻璃装饰板材是一种新型建筑装饰材料。本文利用冲蚀磨损实验研究了影响CaO-Al2O3-SiO2系统烧结法微晶玻璃装饰板材磨蚀行为。讨论了微晶玻璃组成、结构、磨粒粒径、冲蚀角、冲蚀时间对CaO-Al2O3-SiO2系统微晶玻璃的冲蚀性的影响。结果表明:随着微晶玻璃中晶相含量的增加,磨料对其表面的冲蚀磨损量明显下降。微晶玻璃的冲蚀量随冲蚀角的增大、冲蚀时间的增长、磨粒粒度的增大而增加。     

Q235钢基体3Y-TZP/LZAS微晶玻璃梯度涂层冲蚀磨损性能研究

采用涂搪法烧结制备了Q235钢基体3Y-TZP/LZAS微晶玻璃梯度涂层。利用自制的冲蚀磨损试验机,在15°、30°、45°、60°、75°和90°冲蚀角下,控制冲蚀时间,分别对不同层数梯度涂层进行冲蚀,测定体积冲蚀磨损率。通过SEM对冲蚀后的试样表面进行显微结构分析,研究不同冲蚀角度下梯度涂层的冲蚀磨损机制。结果表明:梯度涂层的体积冲蚀磨损率随冲蚀角度增大均呈现出先增大后减小的趋势,并在60°时达到最大值;梯度涂层的抗冲蚀性能随着层数的增加而增强;低角度下的冲蚀机制主要为切削、犁削效应引起的切削磨损,高角度下的冲蚀机制主要为捶击锻打效应引起的脆性断裂,60°冲蚀角下捶击锻打效应和切削、犁削效应都比较强,涂层磨损量最大。     

基于有限元模拟研究不同形状磨料对高铝砖的冲蚀磨损

以石英砂、棕刚玉、碳化硅为磨料,对III等高铝砖进行常温垂直冲蚀磨损。假定磨料为动能相同的球体、正方体和正四棱锥,建立单粒子冲蚀模型对冲蚀试验进行有限元模拟,采用线弹性材料模型分析不同形状磨料的冲击行为,采用JH-2材料模型计算靶材的冲蚀磨损率和最大等效应力。结果表明:正方体和正四棱锥磨料的接触时间、垂直压入深度、冲击效率均相当,且远大于球体磨料;冲蚀磨损率的模拟结果和试验结果、靶材最大等效应力三者均与磨料圆度成反比,模拟结果略低于试验结果。对靶材冲蚀前后表面进行显微结构分析,钝角磨料(石英砂)的主要冲蚀机制是缺陷部位的断裂和基质的切削,尖角磨料(碳化硅)的主要冲蚀机制是骨料的断裂和基质的犁削。     

粘土改性环氧树脂浆液冲蚀磨损研究

研究了粘土改性环氧树脂的浆液体冲蚀磨损性能。研究表明:不同粘土加入量的改性环氧树脂的冲蚀磨损率随冲蚀角度的变化规律相同,变化曲线呈W形,材料表现出从脆性材料向塑性材料过渡的冲蚀磨损特征;粘土改性环氧树脂的冲蚀磨损率随粘土加入量增加而降低,但磨损率下降不是线性的,当粘土加入量在0~1%之间时环氧树脂的磨损率下降速度大,而随着粘土加入量进一步升高,环氧树脂磨损率降低速度缓慢。     

大粒径磨料作用下高铝砖气固冲蚀磨损的"粒径效应"

以平均粒径分别为0.28 mm、0.40 mm、0.52 mm、0.80 mm的棕刚玉为磨料对I等高铝砖进行常温垂直气固冲蚀磨损试验,对磨料和靶材冲后表面进行扫描电镜显微结构分析,在宽粒径范围内研究磨料粒径对靶材耐磨性与冲蚀机制的影响.借助ANSYS/LS-NYNA软件建立多粒子冲蚀模型,分析不同磨料粒径下的冲蚀行为.结果表明:I等高铝砖出现"粒径效应",临界粒径0.40 mm;靶材最大等效应力随磨料粒径的增加而增加;平均粒径≥0.40 mm时磨料发生破碎,0.28 mm、0.40 mm、0.80 mm磨料冲蚀下靶材的主要冲蚀机制分别是基质和骨料微切削、基质和骨料断裂、缺陷处断裂.     

高铝质耐火材料常温耐磨性能研究

选用棕刚玉为磨料,在压缩空气加速磨粒的冲蚀磨损试验机上分别对高铝质浇注料和高铝耐火砖的原始成型面和砖体内切割面进行了冲蚀磨损实验.探究了高铝质耐火材料的原始成型面和砖体内切面在不同冲蚀角度、磨料速度及冲蚀时间下的体积冲蚀磨损率,采用扫描电子显微镜(SEM)观察经不同冲蚀时间冲蚀后试样的微观形貌.实验结果表明:在不同的冲蚀角度、磨料速度及冲蚀时间的试验条件下,高铝质耐火材料内切面的耐冲蚀性均优于其原始成型面的耐冲蚀性,且在冲蚀过程中,原始成型面存在加速和稳态两个冲蚀过程.     

纤维增强塑料注射充模过程中纤维对模具的冲蚀磨损模拟

针对塑料模具在玻璃纤维冲蚀下造成的表面磨损问题,运用有限元软件ANSYS/LS-DYNA建立了模具材料多颗粒冲蚀有限元模型,进行三维显式冲击动力学计算,研究纤维在不同冲蚀速度和冲蚀角度下对模具的冲蚀规律,分析冲蚀机理。结果表明,玻璃纤维对模具的冲蚀过程以微切削为主;玻璃纤维对模具的冲蚀磨损率随着冲蚀速度的增加而增加,随着冲蚀角度的增加而呈现先增加后减小的趋势。     

气固两相流作用下工程玻璃的冲蚀性能及损伤机理研究

根据内蒙古中西部地区风沙环境特征,采用气流挟沙喷射法,通过模拟风沙环境侵蚀实验系统,对比分析冲蚀力学参数对不同特性工程玻璃冲蚀率的影响规律,并结合扫描电镜(SEM)分析其损伤机理.结果表明:钢化玻璃的冲蚀率随冲蚀角度的增加而增大,在90°时达到最大值,表现出脆性材料的特征;有机玻璃的冲蚀率随冲蚀角度增加先增大后减小,在45°处达到最大值,90°时为最小值,表现出半塑性材料的特征.两种玻璃的冲蚀率随沙流量的增加,先迅速减小后趋于平缓;随速度的增加而增加.在高角度冲蚀时,钢化玻璃和有机玻璃冲蚀率和冲蚀速度回归曲线的速度指数较接近,分别为3.94和3.66,均偏离了理论预测的范围.钢化玻璃高角度冲蚀损伤严重,其表面冲蚀损伤机理是与塑性区相关的残余应力,在冲击部位产生横向裂纹,裂纹不断扩展在材料表面交叉引起材料流失;有机玻璃低角度冲蚀磨损严重,其损伤机制主要是微切削作用,损伤程度由材料的硬度控制.     

环氧树脂涂层的耐冲蚀磨损性能

配制了3种环氧树脂涂层配方,测试其耐冲蚀磨损性能。结果发现,以纳米蒙脱土为填料、203#聚酰胺为固化剂的环氧树脂涂层的耐冲蚀磨损性能最佳:随着磨料粒度、磨料质量分数、试验机主轴转速的增大,冲蚀磨损率增加,攻角为45°时冲蚀磨损率最大,60°时最小;推荐最佳耐磨涂层的配方为:w(环氧树脂E-44):w(环氧树脂E一51):w(203#聚酰胺):w(纳米蒙脱土)为30:70:80:7。     

Influence of interface morphology on erosion failure of thermal barrier coatings

The thermal barrier coating system (TBCs) has complex structure and works in severe service environment. Erosion is one of the main factors causing the failure of TBCs. In the present study, the particle erosion process of atmospheric plasma sprayed (APS) thermal barrier coatings at elevated temperature was simulated by the finite element method. The effects of interface morphology on the penetration depth, particle ricochet velocity and interface stress state were studied, and the key parameters such as particle size, initial velocity and erosion position were also considered. The cosine curve with constant wavelength and varying amplitude was used to represent different interface roughness of TBCs. The results show that the interface morphology has little effect on the penetration depth of top coat (TC) and the particle ricochet velocity. The influence of particle erosion position related to the interface morphology is obvious. Basically, the greater the interface roughness is, the more violent the interfacial stress fluctuation is. During the erosion process, the stress in the middle of the interface is significantly higher than that at other positions. These results facilitate understanding of the particle erosion failure mechanism of APS TBCs. The influence of interface morphology should be considered in erosion research.     

Erosion characteristics of N720/alumina oxide/oxide ceramic matrix composites in a combustion environment

The erosion behavior of N720/Alumina oxide/oxide composite was investigated under a combustion environment to better represent particle ingestion of a jet engine. The effect of particle velocity, particle size, temperature and impingement angle were investigated. In addition, room temperature studies were also conducted for comparison. Eroded sites were investigated using optical and scanning electron microscopy to understand the extent of erosion and erosion mechanisms. The results indicate that erosion rate increased with an increase in particle velocity and particle size. Also, erosion rate increased from room temperature to 815 °C and then decreased from 815 °C to 1200 °C. Brittle fracture is the predominant mode under normal impacts and as the impact angle is decreased increased ploughing/wear is evident.     

Three‐body abrasive wear behavior of short jute fiber reinforced epoxy composites

In present investigation, the three‐body abrasive wear behavior of short jute fiber reinforced epoxy composites was studied. The effect of various parameters such as fiber loading, sliding velocity, normal load, and abrasive size on the abrasive wear rate of composite has been analyzed. Abrasive wear study has been carried out using a dry sand/rubber wheel abrasion tester. The abrasive wear and friction characteristics of these composites are analyzed successfully using Taguchi orthogonal array and analysis of variance. The experimental study reveals that sliding velocity, fiber loading, and abrasive size have greater influence on the specific wear rate of the composites. The results show that the specific wear rate of the composites decreases with the increase in sliding velocity whereas, with the increase in normal load the specific wear rate increases. The study also revealed that the coefficient of friction of the composites increases up to a certain value than decreases with the increase in normal load as well as sliding velocity. The worn surfaces of the abraded specimens were examined using SEM to understand the mechanism involved in material removal. POLYM. COMPOS., 270–278, 2016. © 2014 Society of Plastics Engineers     

基于防磨结构的旋风分离器性能优化

基于气固两相流和冲蚀理论对常规Stairmand旋风分离器和防磨型旋风分离器冲蚀规律进行了研究. 结果表明,对常规旋风分离器,其壁面冲蚀磨损速率从筒体顶端向下逐渐减小,在筒体L1/H1=0.8以下区域,磨损速率基本保持不变;在L1/H1=0.8以上区域,冲蚀磨损呈增大趋势,最大为2.3′10-6 kg/(m2×s);在锥体L2/H2=0.35以下区域,冲蚀速率逐渐减小;而在L2/H2=0.35以上区域呈逐渐增大趋势,在锥体顶端达最大值2.0′10-7 kg/(m2×s). 对防磨型旋风分离器,在筒体L1/H1=0.8以上区域,壁面最大冲蚀速率为0.5′10-6 kg/(m2×s),远小于常规旋风分离器. 在锥体从锥底向上冲蚀速率逐渐减小,在锥体顶端为0.4′10-7 kg/(m2×s),小于常规旋风分离器. 在小粒径范围内,分离效率随粒径增加而基本呈线性递增趋势. 粒径大于4 mm时,防磨型旋风分离器具有较高的分离效率. 压降随防磨板高度增加逐渐减小. A3型防磨分离器压降为360 Pa,小于常规分离器压降550 Pa. 为了降低旋风分离器壁面的冲蚀磨损,减少出口压降损失,粒径大于4 mm时,可选择最合理的B1型防磨分离器提高旋风分离器的防磨性能,从而延长使用寿命.     

B4C/SiCw陶瓷喷砂嘴的制备及其冲蚀磨损机理研究

采用热压烧结工艺制备了B4C/SiCw陶瓷喷砂嘴,研究了SiC晶须的含量对B4C/SiCw陶瓷材料性能的影响.以SiC和Al2O3磨料对B4C/SiCw陶瓷喷砂嘴进行冲蚀磨损试验,研究不同磨料对B4C/SiCw陶瓷喷砂嘴冲蚀磨损的影响,分析了其冲蚀磨损机理.结果表明:B4C/SiCw陶瓷喷砂嘴的冲蚀磨损机理主要表现为脆性断裂和磨料粒子对喷嘴的切入所造成的微观切削作用.磨料的硬度和粒度对陶瓷喷嘴的磨损有重要的影响,磨料的硬度和粒度越大,陶瓷喷嘴的磨损速度加快.     

狭窄矩形通道内液固两相磨蚀特性

液固两相磨蚀研究主要集中于圆管弯头和射流工况,板式换热器等狭窄矩形通道内液固两相磨蚀特性的研究鲜见报道。在Fluent软件及其二次开发框架内构建了描述稀疏颗粒液固两相磨蚀特性的CFD-DPM-磨蚀耦合数学模型框架,研究了存在圆柱体阻挡物的狭窄矩形通道内两相流动特性和壁面磨蚀特性,揭示了壁面和固体颗粒的相互作用机制。研究结果表明：阻挡物的存在显著改变了狭窄矩形通道壁面的磨蚀行为;磨蚀速率随液固流速和壁面粗糙度的增加而增加,因此,保证设备较低的入口流速和壁面粗糙度对延长设备寿命至关重要;磨蚀速率随颗粒粒径的增加先增加后降低,在60μm左右时达到极大值;球形度系数对磨蚀行为影响较小。引入量纲为1颗粒尺寸,阐述了液相边界层束缚颗粒运动的作用机制;与光滑壁面工况相比,颗粒以较大能量高频撞击粗糙壁面,导致了壁面磨蚀较快。液固两相以较低的角度和速度撞击壁面,壁面材料去除机理以微切削为主。     

Performance of the silicon carbide coating under erosion wear by erosion by solid particles

In this article, the phenomenon of erosion by solid particles on the silicon carbide coating (SiC) deposited on AISI 304 stainless steel substrates was analyzed. The specimens used were 25 mm square and 3 mm thick, using 300–450 μm silicon carbide as abrasive particles. Experimental tests were performed on an apparatus developed in accordance with some parameters of the ASTM G76-95 standard. Four angles of impact at 30°, 45°, 60°, and 90° are contemplated with an approximate particle velocity of 25 ± 2 m/s with a maximum exposure time of 10 min per specimen, taking measurements of weight intervals every 2 min to determine the mass loss. The wear mechanisms that were identified to small angles were: plastic deformation, displacement of material, and plow mechanisms. While at higher impact angles, the mechanisms were mainly: cutting, pitting, fractures, and cracks. It was observed that the rate of erosion depends on the angle of incidence of the abrasive particles. The results indicated that a higher damage zone was obtained at 30° of impact angle; on the other hand, at an angle of 90° there was less damage.