凹坑型仿生形态环块样件接触问题有限元数值模拟

利用ANSYS建立了环块样件接触的实体模型,将齿轮接触问题进行了等效简化;根据ANSYS接触问题的有限元分析方法与仿生学表面形态优化设计技术,在环块样件的接触面区域形成了九种不同分布的凹坑型仿生表面微观形态,完成了光滑环块样件与九种凹坑型仿生形态环块样件接触问题的三维有限元数值模拟,进行了光滑与凹坑型仿生形态环块样件接触应力的对比分析,得出:仿生形态环块样件接触区域接触应力峰值高于光滑样件,但仿生形态环块样件接触区域的平均接触应力值低于光滑形态。     

仿生肋条结构表面深松铲刃的磨料磨损特性

基于仿生学原理,将栉孔扇贝的瓣表面具有良好耐磨性能的棱纹形结构应用于深松铲刃的磨损表面结构设计中。采用65Mn和T10两种材料设计并制备3种仿生类型深松铲刃试验样件,并在土壤磨料作用下与普通平板型试验样件进行了对比磨料磨损试验。结果表明:在不同的滑动速度下,65Mn、T10仿生试验样件比平板型样件的质量磨损量分别减小了17%~30%、13%~24%。肋条分布间距为1.5倍底宽的仿生试验样件的磨损量最低,T10样件的耐磨性优于65Mn。     

仿生耦合功能表面应力-应变本构关系

采用试验优化设计方法对相同试验条件下凹坑形仿生光滑试样以及具有仿生耦合表面的非光滑试样进行了干摩擦磨损试验对比研究。在相同试验条件下,凹坑形仿生非光滑试样磨损率小于光滑试样,即前者耐磨性较高。在此基础上,作者进行了受压状态下试样表面应力的试验测试和ANSYS有限元计算分析,探讨了非光滑凹坑对试样表面应力-应变分布的影响。结果表明:在受力状态下,仿生非光滑凹坑改善了试样表面的应力分布,使非光滑试样表面凹坑间的区域局部应力明显小于光滑试样表面的应力,即产生了局部低应力区。本文初步提出了非光滑结构的力矩效应和应力缓释效应。     

凹坑形貌对线接触摩擦副耐磨性的影响

在线接触摩擦副中,非光滑结构单元的凹坑、凸包、波纹、鳞片形态等表面凹坑形貌对其耐磨性有一定的影响,其中凹坑的直径、深度对耐磨性的影响十分显著。以圆形凹坑非光滑形貌为例,采用有限元仿真分析的方法,对非光滑表面凹坑不同直径和深度的磨损过程进行了分析,研究了仿生非光滑表面对摩擦副耐磨性影响的程度。研究结果表明:线性摩擦副工作过程中,凹坑间距为1 000 m的条件下,摩擦副表面的等效应力和摩擦力随着圆形凹坑直径的增大而增大,随其深度的增大而呈抛物线增长;且在凹坑直径为100 m、深度为300 m时,矩形块的耐磨性最优。     

仿生凹坑型吸盘设计与试验

为了提高吸盘的吸附性能,基于水蛭吸盘表面存在的凹坑形态,运用仿生学原理,在常规吸盘表面设计凹坑形态,使吸盘工作表面存在多个小型吸盘,提高吸盘的吸附性能。运用部分正交多项式回归分析,探究凹坑形态的直径、单排凹坑数量及排间距对吸盘吸附力的影响。试验表明,不同凹坑的形态参数对吸盘吸附力具有不同的影响效果,当凹坑直径为1.5 mm、单排凹坑的数量为40个及排间距为4 mm时,仿生吸盘在基底表面的吸附力为49.54 N,相对于标准吸盘在基底表面的吸附力提高49.21%。建立设计因素与评价指标间的数学回归模型,确定对吸盘吸附力影响的显著性主次顺序为排间距、凹坑直径、单排凹坑数量。仿真分析表明,工作表面存在的凹坑形态改变了吸附时吸盘表面接触压力及摩擦应力的分布,并且仿生吸盘工作表面的摩擦应力和接触压力均大于标准吸盘,增大了仿生吸盘在基底表面的吸附力。     

新疆岩蜥三元耦合耐冲蚀磨损特性及其仿生试验

选取新疆岩蜥为典型动物,以形态、结构、材料作为因素设计仿生耦合试样,通过喷砂试验检验耦合试样表面的冲蚀磨损特性。喷砂试验选用粒径为1000μm的Al2O3颗粒为磨料,对LY12硬铝合金与45#钢为基底的仿生耦合试样进行试验。结果表明,在冲蚀时间为180 s,入射角为30°,入射距离为200 mm,空气压力为0.4 MPa条件下,耦合试样耐冲蚀磨损性能较对照试样提高18.7%。耦合试样特征因子最优组合为以LY12硬铝合金为基底材料,非光滑单元形态的形状为圆形凹坑、直径为3 mm,单元间距为6 mm的规则分布,表面涂层(Al2O3+13%TiO2)厚度为100μm。     

仿生非光滑表面在混合润滑状态下的摩擦性能

模仿蚯蚓的非光滑表面形态及其分泌体表液的摩擦行为和作用,利用摩擦试验台对模拟蚯蚓体表形态的凹坑、导角通孔、通孔三种仿生非光滑表面形态进行了滴油混合润滑摩擦试验。试验结果表明,在混合润滑情况下,接近蚯蚓背孔的通孔形仿生非光滑表面结构具有优良的减阻、耐磨效应,并从非光滑形态对润滑状态影响规律及对摩擦界面材料特性影响规律探讨了仿生非光滑形态对摩擦性能的影响机理。     

轴流风机仿生叶片降噪试验研究及机理分析

根据长耳鸮翼前缘非光滑形态降噪特性,设计了仿生前缘非光滑轴流风机叶片。试验研究表明:仿生非光滑叶片在50~2000 Hz的频段上噪声值明显小于原型风机叶片,最大降噪率为2.52%;影响仿生非光滑叶片降噪效果的主次因素为非光滑单元间距t、非光滑单元高度h和非光滑单元个数。计算机模拟分析表明,仿生前缘非光滑形态降噪机理主要为:减少翼型表面紊流附面层压力脉动并延缓翼型后部涡流分离脱落;有效减少气流流经前后翼型表面时翼型间扰流作用,起到良好的导流作用,使后翼型来流平稳,气流噪声降低。     

柔性与形态耦合仿生抗冲蚀三维数值模拟

利用有限元软件ANSYS/LS-DYNA,分别对4种具有不同表面形态(光滑、凹坑形、柔性与光滑耦合、柔性与凹坑耦合)的试件的耐冲蚀性能进行了三维数值模拟,计算出冲蚀磨损过程中等效应力的变化情况,并与试验结果进行了对比.结果表明,数值模拟的试件耐冲蚀顺序依次为:柔形与凹坑耦合>柔形与光滑耦合>凹坑形态>光滑形态,该结果与...     

仿生非光滑表面材料与铝合金制件间的减黏

根据工程仿生学原理,用45^#钢和高速钢材料通过激光加工的方式制备出具有网格状结构表面的仿生非光滑试样,并与光滑表面试样在电子万能试验机上进行了脱附对比试验。结果表明,仿生非光滑表面试样的抗黏附性能明显优于光滑表面试样,其与制件间的黏附力比光滑表面降低4．7％～20．9％。观察发现,非光滑单元体的凹坑结构与制件接触界面间形成的空隙降低了试样与制件间的实际接触面积,是使仿生非光滑表面试样具有良好抗黏附性能的主要原因。仿生非光滑结构为提高材料表面的抗黏附性能开辟了一条新途径。     

Failure analysis of wear of main clutch separating ring of heavy vehicles

The severe wear of separating ring is considered to be a main reason which leads to the improper declutch of the main clutch of heavy vehicles. The wear mechanism of the separating ring is not well understood. Scanning electron microscopy and transmission electron microscopy were employed to analyze the surface features and dislocation characteristics of the separating ring. The typical features of furrows and rolled tongue-like metal were found on the surface of separating ring by scanning electron microscopy observation, which can be considered as a major indi cation of the grain-abrasion. A zone of high density dislocation was noted on the subsurface of the separating ring by transmission electron microscopy observation, which implies the contribution of the severe impact on the surface of the separating ring in the wear process. The influences of the structure of the separating ring, the service condition and the in-service stress distribution on the wear behavior, were also analyzed. The results show that the failure of separating ring results from the impact wear and grain-abrasion together with the plastic deformation.     

Failure analysis of wear of main clutch separating ring of heavy vehicles

The severe wear of separating ring is considered to be a main reason which leads to the improper declutch of the main clutch of heavy vehicles. The wear mechanism of the separating ring is not well understood. Scanning electron microscopy and transmission electron microscopy were employed to analyze the surface features and dislocation characteristics of the separating ring. The typical features of furrows and rolled tongue-like metal were found on the surface of separating ring by scanning electron microscopy observation, which can be considered as a major indication of the grain-abrasion. A zone of high density dislocation was noted on the subsurface of the separating ring by transmission electron microscopy observation, which implies the contribution of the severe impact on the surface of the separating ring in the wear process. The influences of the structure of the separating ring, the service condition and the in-service stress distribution on the wear behavior, were also analyzed. The results show that the failure of separating ring results from the impact wear and grain-abrasion together with the plastic deformation. Foundation item: Project(41327040101) supported by the Pre-research Fund of General Armament Department; project(51489010104QT0101) supported by the Fund of State Key Laboratory of Re-manufacture Technology     

高速干切削淬硬AISIH13钢的硬质合金刀具（YW2）磨损机理

以YW2对淬硬态AISIH13钢进行高速干切削试验,采用电子显微镜和能谱仪分别进行形貌观察及元素分析,研究了刀具磨损机理。结果表明,温度梯度是高速干切削刀具磨损的本质原因。前刀面呈不规则的凹坑状,以粘结磨损为主;后刀面呈小斜面状,以疲劳剥落为主。同时,前、后刀面上也发生了氧化反应及元素扩散。     

Al2O3陶瓷与铸铁副在空气和蒸馏水润滑下的滑动磨损

在室温、干摩擦(空气)及蒸馏水润滑条件下使用环块磨损试验机进行Al2O3陶瓷和球墨铸铁、灰铸铁及钢配副时的滑动磨损试验.结果表明:蒸馏水润滑下Al2O3及铸铁的磨损体积均小于在干磨擦条件下;在同一润滑条件下,钢的磨损体积大于铸铁磨损体积,球墨铸铁磨损体积最小;陶瓷Al2O3磨损体积在干摩擦时与铸铁配副时比与钢配副时要小得多.对Al2O3磨面进行形貌及能谱分析,发现在干摩擦条件下,Al2O3磨面有大量铸铁或钢的转移物组成的迁移膜,在蒸馏水润滑条件下则没有.分析认为,铸铁中石墨在于摩擦时能起到较明显的固体润滑剂作用,相对地减小了磨损,而在蒸馏水润滑下石墨的润滑作用己大大减弱.     

仿生凹坑与纳米碳化硅/镍基复合镀层耦合表面的磨损性能

为了探讨凹坑形态与纳米碳化硅/镍基复合镀层耦合表面的磨损性能,采用激光技术和电沉积技术制备了由凹坑形态和纳米碳化硅/镍基复合镀层构成的仿生耦合表面,并进行了摩擦和磨损试验。结果表明,仿生耦合表面的磨损性能高于单纯复合镀层的磨损性能;随着磨损载荷的增加和磨损时间的延长,试样表面磨损机制由以塑性磨损为主逐渐转变成以粘着磨损、磨粒磨损为主的磨损机制。     

评定钢丝的微动摩擦磨损参数研究

以点接触式提升钢丝绳为研究对象，在实验室建立了钢丝绳中钢丝的微动磨损模型．在自制的钢丝微动磨损试验机上进行微动磨损实验，考察了接触载荷、微动时间和振幅的变化对钢丝试样磨损深度的影响，并用综合参数pv值和pvt值评定微动磨损深度的变化．结果表明，相同微动时间下磨损深度随pv值的增加而增大，相同接触载荷下磨损深度随pv值增大而减小，磨损深度和综合参数pvt值之间基本成线性关系．同时通过微动过程中摩擦系数的变化、磨损产生的磨屑以及磨痕形貌，分析微动磨损过程中磨损机制随微动实验条件的变化规律。     

Abrasive Wear Map of Polymer Tapes in Sand Dust Environment

To make clear the wear conditions of ATM （Automatic Teller Machine） tribosystem when servicing in Chinese sand dust environment, abrasive wear of two kinds of polymer tapes specified for ATM, PI （Polyimide） and PEN （Polyethylene-2, 6-naphthalenedicarboxylate）, was investigated in simulated sand dust environment with ATM tape-scraper tribosystem under various conditions of loads and sliding distances. The surface profiles of worn tape were measured with a surface profiler in order to calculating the wear cross-section areas and the wear volumes. The specific wear rates of polymer tapes were calculated under load conditions of 0.6, 1 and 1.5 N, and wear mechanisms were in- vestigated with optical topography photos. As main results, the specific wear rates show stage variations in the wear process and the wear resistance of polymer tape shows good relationship with the mechanical deformation factors. In consideration of the service life, four wear models are generalized according to the magnitude of specific wear rates, which include no wear, mild wear, normal wear and severe wear model and the corresponding wear mechanisms for the four wear models are discussed with typical worn topographies. Based on the wear models and corresponding wear mechanisms, the abrasive wear maps of two polymer tapes servicing in sand dust environments are concluded for its industrial applications.     

变双曲圆弧齿线圆柱齿轮传动几何特性分析

根据变双曲圆弧齿线圆柱齿轮的加工原理与推导得到的齿面方程,确定方程各相关参数的取值范围。基于得到的齿面方程,依据微分几何,得到变双曲圆弧齿线圆柱齿轮凹、凸面主曲率的计算方法。基于空间啮合原理,计算齿轮副在某一输入角速度下两齿面啮合点处的相对运动速度。根据已得到的齿面曲率、相对运动速度计算方法,推导变双曲圆弧齿线圆柱齿轮副滑动率的计算公式。以某一确定设计参数的变双曲圆弧齿线圆柱齿轮副作为算例,计算其主曲率、诱导法曲率和滑动率,分析其变化趋势;并计算不同设计参数下的滑动率,分析设计参数对其影响,以此作为分析该齿轮副设计及优化的参考。分析结果表明：对变双曲圆弧齿线圆柱齿轮来说,模数越大,齿数比越小,齿线半径越大,则滑动率的变化范围越小,齿轮副在运转过程中的磨损更均匀;就磨损而言,大模数、小齿数比、大齿线半径的齿轮具有更好的性能。建立变双曲圆弧齿线圆柱齿轮副滑动率与磨损之间的量化关系,反映出其正相关关系,为齿轮磨损量的计算提供参考。