Research on the design method for uniform wear of shield cutters in sand-pebble strata

During shield tunneling in highly abrasive formations such as sand–pebble strata,nonuniform wear of shield cutters is inevitable due to the different cutting distances.Frequent downtimes and cutter replacements have become major obstacles to long-distance shield driving in sand–pebble strata.Based on the cutter wear characteristics in sand–pebble strata in Beijing,a design methodology for the cutterhead and cutters was established in this study to achieve uniform wear of all cutters by the principle of frictional wear.The applicability of the design method was verified through three-dimensional simulations using the engineering discrete element method.The results show that uniform wear of all cutters on the cutterhead could be achieved by installing different numbers of cutters on each trajectory radius and designing a curved spoke with a certain arch height according to the shield diameter.Under the uniform wear scheme,the cutter wear coefficient is greatly reduced,and the largest shield driving distance is increased by approximately 47%over the engineering scheme.The research results indicate that the problem of nonuniform cutter wear in shield excavation could be overcome,thereby providing guiding significance for theoretical innovation and construction of long-distance shield excavation in highly abrasive strata.

Parameters studies for rail wear in high-speed railway turnouts by unreplicated saturated factorial design

Rail wear is one of the main reasons for reducing the service life of high-speed railway turnouts in China. The rail wear characteristics of high-speed railway turnouts are influenced by a large number of input parameters of the complex train-turnout system. To reproduce the actual operation conditions of railway turnouts, random distributions of these inputs need to be considered in rail wear simulation. For a given nominal layout of the high-speed railway turnout, 19 input parameters for rail wear simulation in high-speed railway turnouts are investigated based on orthogonal design of experiment. Three dynamic responses(wheel-rail friction work, normal contact force and size of contact patch) are defined as observed values and the significant factors(direction of passage, axle load, running speed, friction coefficient, and wheel and rail profiles) are determined by two unreplicated saturated factorial design methods, including the half-normal probability plot method and Dong 93 method. As part of the associated rail wear simulation, the influence of the wear models and the local elastic deformation on the rail wear was separately investigated. The calculation results for the wear models are quite different, especially for large creep mode. The local elastic deformation has a large effect on the sliding speed and rail wear and needs to be considered in the rail wear simulation.

Design and Development of Composite Plywood that Integrates Fire Resistance,Water Resistance and Wear Resistance

In order to improve the fire resistance,water resistance and wear resistance of ordinary plywood products in the wood processing industry,three composite structures of plywood products S1,S2 and S3 were designed in this paper,and a reasonable production process was proposed.Through the physical and mechanical properties and fire resistance testing and technical and economic analysis,the applicability of composite plywood was evaluated.The results of the study showed that the physical mechanics of the three kinds of composite structure plywood met the standard requirements,and their fire resistance was far better than that of ordinary plywood.Among them,the S1 structural board had the best overall physical and mechanical properties.The S3 structural board showed the best fire resistance,which was about 1.9 times more than that of ordinary plywood,and the added cost was the lowest.The thin cork board added to the S2 structural board had poor fire performance since the air in the cork board cavities had a certain combustion-supporting effect,which inhibited the fire resistance of high-pressure laminate(HPL)layer.Moreover,the additional cost of the S2 board was the highest,and its comprehensive performance was the worst.The S3 structural plywood product composed of HPL fireproof board with a thickness of about 1 mm in the surface layer and ordinary plywood with a thickness of about 12 mm in the core layer was the most cost-effective product,which could meet the needs of various fields such as construction,home furnishing,decoration and transportation.

EXPLOITATION AND APPLICATIONS OF METASTABLE AUSTENITE MATRIX WEAR ALLOYS

Fe based cast alloys with double phases structure of m etastable austenite m atrix an d eutecticcarbide M7 C3 were provided with the excellent properties of high abrasion resistance andhigher i m pact toughness . An i m portant reason of high abrasion resistance is hard ness violentincreasing on the m atrix surface because of w ear easily induced m artensite transfor m ation . The exploitation and applications of m etastable austenite m atrix wear alloys of Fe C Cr Nisyste m and Fe C Cr Mn system were described in this paper . The excellent properties of thesealloys w ill be sufficiently indicated by authors’exa m ples . To exploit a class of these alloyswith high abrasion resistance and various im pact toughness for m eeting the requirem ent of dif ferent environ ment , the proble m of the structure design of metastable austenite m atrix wearalloy w as also described in this paper .

PHASE STRUCTURE FACTOR AND INTERFACE CONJUNCTION FACTOR OF CAST IRON AND ITS COMPOSITION DESIGN

Theempiricalelectrontheory of solidsand molecules( EET) and theimproved TFDtheory wereapplied tocalculatethe phasestructurefactorsand interfaceconjunction factorsofcom mon alloying elementsincastiron. Akind of Si- Mo- Cu ductileiron with rareearth Mg asnodularizer was designed accordingtothese valenceelectron structure parameters. Actual applicationtestsshow thatthelongevity of thisiron is 1.5 timesof thatof high manganesesteel. This accordance of theoretical results and actual effectsshows the composition design methodcan beused in othercastiron research.

Enhancement of wear resistance of Ti–6Al–4V alloy by picosecond laser surface micro texturing process

A pulsed,picosecond Nd:YAG laser with a wavelength of 532 nm is used to texture the surface of grade 5 titanium alloy(Ti–6Al–4V)for minimizing its wear rate.The wear properties of the base samples and laser surface textured samples are analyzed by conducting wear tests under a sliding condition using pin-on-disk equipment.The wear tests are conducted based on the Box–Benhken design,and the interaction of the process parameters is analyzed using response surface methodology.The wear analysis is conducted by varying the load,rotating speed of the disc,and track diameter at room temperature with a sliding distance of 1500 m.The results demonstrate that the laser textured surfaces exhibited a lower coefficient of friction and good anti-wear properties as compared with the non-textured surfaces.A regression model is developed for the wear analysis of titanium alloy using the analysis of variance technique.It is also observed from the analysis that the applied load and sliding distance are the parameters that have the greatest effect on the wear behavior followed by the wear track diameter.The optimum operating conditions have been suggested based on the results obtained from the numerical optimization approach.

Taguchi approach to influence of processing parameters on erosive wear behaviour of Al7034-T6 composites

Taguchi technique was used to predict the influence of processing parameters on the erosive wear behavior Al7034-T6composite reinforced with SiC and Al2O3particles in different mass fractions.These hybrid metal matrix composites(HMMCs)werefabricated by using a simple technique called stir casting technique.Scanning electron microscope(SEM)was used to study thesurface morphology of the composite and its evolution according to processing time.The design of experiment(DOE)based onTaguchi’s L16orthogonal array was used to identify various erosion trials.The most influencing parameter affecting the wear rate wasidentified.The results indicate that erosion wear rate of this hybrid composite is greatly influenced more by filler content and impactvelocity respectively compared to other factors.This also shows the significant wear resistance with the increase in the filler contentsof SiC and Al2O3particles,respectively.

Tool Wear Prediction in Micro-end-milling with Hard Material

The applications of micro machining have increased drastically in the last ten years. However, tools with less than lmm diameter using for micro-mills have very short and unpredictable life when they are used to cut hard metals. In this study, preliminary design of experiment （DOE） test program was conducted to investigate and i- dentify the factors affecting tool wear at the micro-scale with hard material. Analysis of variance （ANOVA） and Taguchi method were efficient to determine appropriate cutting condition and the effect of parameters. A simple model was also developed to predict the width of slots on the workpiece along the cutting length. The obtained re- suits can provide the basic guidelines for parameter setting of micro-end-milling with hard material.

Advances in micro cutting tool design and fabrication

Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality.This technology may offer great potential as well as advantageous process capabilities for the machining of hard-to-cut materials,such as tungsten carbide.The geometrical design and dimension of the tool cutting edge is a key factor that determines the size and form accuracy possible in the machined workpiece.Currently,the majority of commercial microtools are scaled-down versions of conventional macrotool designs.This approach does not impart optimal performance due to size effects and associated phenomena.Consequently,in-depth analysis and implementation of microcutting mechanics and fundamentals are required to enable successful industrial adaptation in microtool design and fabrication methods.This paper serves as a review of recent microtool designs,materials,and fabrication methods.Analysis of tool performance is discussed,and new approaches and techniques are examined.Of particular focus is tool wear suppression in the machining of hard materials and associated process parameters,including internal cooling and surface patterning techniques.The review concludes with suggestions for an integrated design and fabrication process chain which can aid industrial microtool manufacture.

Problems,assumptions and solutions in locomotive design,traction and operational studies

Locomotive design is a highly complex task that requires the use of systems engineering that depends upon knowledge from a range of disciplines and is strongly oriented on how to design and manage complex systems that operate under a wide range of different train operational conditions on various types of tracks.Considering that field investigation programs for locomotive operational scenarios involve high costs and cause disruption of train operations on real railway networks and given recent developments in the rollingstock compliance standards in Australia and overseas that allow the assessment of some aspects of rail vehicle behaviour through computer simulations,a great number of multidisciplinary research studies have been performed and these can contribute to further improvement of a locomotive design technique by increasing the amount of computer-based studies.This paper was focused on the presentation of the all-important key components required for locomotive studies,starting from developing a realistic locomotive design model,its validation and further applications for train studies.The integration of all engineering disciplines is achieved by means of advanced simulation approaches that can incorporate existing AC and DC locomotive designs,hybrid locomotive designs,full locomotive traction system models,rail friction processes,the application of simplified and exact wheel-rail contact theories,wheel-rail wear and rolling contact fatigue,train dynamic behaviour and intrain forces,comprehensive track infrastructure details,and the use of co-simulation and parallel computing.The cosimulation and parallel computing approaches that have been implemented on Central Queensland University’s High-Performance Computing cluster for locomotive studies will be presented.The confidence in these approaches is based on specific validation procedures that include a locomotive model acceptance procedure and field test data.The problems and limitations presented in locomotive traction studies in the way they are conducted at the present time are summarised and discussed.

Research on the Teaching Reform of Women’s Clothing Design Course under the Background of Cultural and Creative Industry Development

With the rapid development of China’s cultural and creative industries,the influence of cultural and creative ideas in fashion design is increasing,and art talents with innovative ability have become hot objects in the society.As the cradle of fashion design talents training and output,colleges and universities in our country shoulder the important task of training fashion design talents in the new period.In the current clothing design curriculum reform,school enterprise cooperation and collaborative innovation have become an important development direction.Under this background,this paper analyzes the teaching reform path of women’s clothing design course in Colleges and universities.

基于EDEM的砂卵石地层盾构刀具磨损特征研究

为揭示砂卵石地层土压平衡盾构典型刀具的磨损特征,指导该地层中盾构刀具的设计、布置等关键问题。采用室内三轴试验及数值离散元软件(EDEM)仿真分析,标定了颗粒-刀具磨损接触参数。依托北京新机场“磁各庄-1号风井”砂卵石盾构工程,构建了砂卵石地层EDEM数值盾构模型,可视化了砂卵石地层土压平衡盾构中典型刀具(楔犁刀、刮刀)的磨损特征,通过实际工程对模型进行了验证。研究表明:(1)以犁松原状砂卵石土为目的的楔犁刀具是掘进主切削刀具,表现为刀头合金表面以及刃角处连续的摩擦磨损形式,磨损量较大;(2)以剥落输排为目的刮刀主要表现为刀身迎土面以及刀头合金表面随机的点蚀磨损,磨损量较小;(3)刀盘径向刀具的磨损量随轨迹半径及刀体高度的增加而增大,同轨迹上高刀的磨损系数高于低刀,高刀对低刀的磨损有保护作用;刀盘径向刀具和环向刀具的“梯次化”布置可延长盾构单次连续掘进距离。

小半径曲线上P75钢轨打磨廓形设计及应用研究

以国内某重载铁路R400 m曲线P75钢轨为研究对象,建立了轮轨接触模型和轮径差曲线描述模型,选取代表性车轮踏面和钢轨廓形,采用轮径差曲线逆向求解法优化了轮轨接触区域钢轨廓形,并依据打磨量最小化原则设计得到了曲线钢轨打磨廓形。建立了实测参数下的车辆-轨道多体动力学仿真模型,对比分析了实测廓形和设计廓形匹配下的动力学指标。按钢轨廓形设计要求,在该R400 m曲线上实施了钢轨打磨试验和轮轨动力学测试。研究结果表明,优化后轮径差曲线趋于平滑,车辆曲线通过能力得到提高,抗脱轨能力得到保持;轮轨关系得到显著改善、轮轨接触点交叉跳跃和集中问题得到缓解;轮轨横向力减小20%以上,脱轨系数减小16%以上,钢轨法向接触应力减小32%以上,轮轨蠕滑力减小26%以上;实施打磨后,轮轨横向力减小34%以上,脱轨系数减小35%以上,钢轨振动加速度减小35%以上;打磨后3个月轨面疲劳伤损未见明显发展,钢轨使用寿命由前一换轨周期的8个月延长至13.5个月。仿真分析和打磨试验验证了钢轨廓形设计方法在重载铁路小半径曲线的应用效果。

专业篮球鞋鞋底综合性能要求与形态设计研究

随着全民运动的全面开展,高性能、专业化的篮球鞋也随之兴起并得到越来越多的关注。专业篮球鞋功能性的高低直接取决于其防滑、缓震、耐磨等性能。本文详细探讨了专业篮球鞋对鞋底性能的各方面要求与研究现状,提出基于综合性能提升的篮球鞋鞋底形态设计方案,如基于支撑性与耐久性的鞋底形态设计、基于防滑性的鞋底形态设计等,并探究了专业篮球鞋现代化、智能化的设计方法与技术,以促进各项鞋底设计方案的实现,丰富专业篮球鞋产品设计的创新方法。

陶瓷框架增强聚四氟乙烯仿生复合材料及其摩擦学性能研究

针对聚四氟乙烯自润滑复合材料耐磨性差这一工业润滑领域的瓶颈问题,本研究中受人牙釉质釉柱/釉间质微观结构的抗磨作用机制启发,基于有限元分析和1种乙酸锆改进的定向冷冻技术,设计制备了定向多孔氧化锆陶瓷框架增强聚四氟乙烯仿生复合材料,并对其力学性能和摩擦学行为进行了试验研究.结果表明:仿生复合材料的自润滑性能良好,力学性能和耐磨性远优于聚四氟乙烯和商用聚四氟乙烯自润滑复合材料易格斯.与易格斯材料相比,仿生复合材料的硬度提高约1.8倍,弹性模量提高约15.2%,抗压强度提高约2.8倍,磨损体积降低约76.6%.仿生复合材料优异的摩擦学性能与定向多孔陶瓷框架增强结构密切相关,这种陶瓷框架增强结构具有Voigt模型(复合材料承载能力上限)承载特性,能够大幅提高复合材料的承载能力,避免材料表面发生严重变形和破坏,提高耐磨性.同时,仿生复合材料的氧化锆陶瓷框架占比仅为25.6%(体积分数),高含量的聚四氟乙烯填料能够有效地在摩擦接触界面形成自润滑转移膜,实现良好润滑.

等效锥度非线性研究及其在踏面设计中的应用

为研究等效锥度非线性特性对车辆系统动力学和磨耗性能的影响,提出可以用于踏面优化设计的非线性特性建议指标。通过对轮轨关系进行细致推导,应用踏面逆向设计快速递推算法,得到具有不同等效锥度非线性特性的踏面,对不同踏面的轮轨关系进行分析。建立车辆系统动力学模型和基于Archard理论的磨耗预测模型,对不同非线性特性踏面的临界速度、横向平稳性、磨耗性能进行对比分析。研究结果表明:非线性因子值过高或过低都会导致临界速度下降,但该指标过高对临界速度影响更大,最大降幅可达20%;等效锥度非线性特性还会影响到踏面的磨耗发展,踏面的初始非线性因子越高,名义等效锥度在磨耗过程中的增长越慢,对延长车轮服役周期是有利的。综合动力学性能及磨耗性能,建议高速列车踏面的非线性因子应取尽可能接近于0的负值。在这一结论的指导下,对S1002CN踏面进行优化设计,得到名义等效锥度为0.1,等效锥度非线性因子为0.013(与S1002CN持平)、-0.002的优化踏面S1002CN_opt1、S1002CN_opt2,优化踏面S1002CN_opt2与S1002CN相比临界速度和横向平稳性有所优化,同时磨耗性能也有所提升。S1002CN_opt2与S1002CN_opt1之间的等效锥度非线性关系在动力学性能及磨耗性能中的表现证明以等效锥度非线性因子限值指导踏面进行优化设计的可行性,研究结果可为踏面设计及轮轨关系研究提供参考。

基于水性环氧乳化沥青的超薄磨耗层级配设计及性能对比研究

为方便在实际工程中选择合适类型的水性环氧乳化沥青超薄磨耗层,本工作采用先乳化后改性的方法制备水性环氧树脂改性乳化沥青。选择AC-10、SMA-10、UWM-10三种不同级配的超薄磨耗层,通过修正的马歇尔试验确定各类型混合料的最佳乳液含量,并通过马歇尔模数、蠕变变形量、破坏拉伸应变、冻融劈裂强度比、动态模量、疲劳寿命次数、构造深度等评价指标对它们的混合料各项性能进行了检验对比。结果表明:超薄磨耗层AC-10、SMA-10、UWM-10的最佳乳液含量分别为8.7%、8.5%和7.6%。相比空白样,水性环氧树脂的加入显著改善了超薄磨耗层混合料的高温稳定性能、抗水损害性能、抗疲劳性能以及抗滑性能。三种超薄磨耗层中,AC-10的低温抗裂性能较强,SMA-10和UWM-10的高温稳定性能和抗疲劳性能较好,与此同时,UWM-10表现出更加优异的抗水损害能力及抗滑性能。

均载组合式小轮径货车转向架车轮型面优化设计研究

小轮径转向架技术是驼背运输车辆的关键技术,小轮径低地板驮背车车轮型面磨耗问题严重,对其动力学性能造成严重影响,为了进一步提升其服役性能,对小轮径低地板驮背车车轮型面进行优化设计。首先建立小轮径低地板驮背车动力学模型,然后利用轮径差反向设计方法对车轮型面进行优化,最后利用车辆动力学模型对优化后型面的车辆动力学性能和磨耗特性进行验证分析。结果表明,优化后型面进一步降低了车轮等效锥度,同时减小了轮轨法向接触应力。通过对比优化前后动力学特性,优化后车轮型面有效提升了空重车状态下的临界速度,空车临界速度较LM踏面提高23.3%,重车临界速度较LM踏面增大17.54%。同时优化后型面有效提升了车辆的平稳性和曲线通过性能,最后利用车轮磨耗模型计算了直线段和曲线段的车轮磨耗,优化后曲线外侧车轮磨耗最大深度减小54.8%,曲线内侧车轮磨耗最大深度减小48.13%,型面优化可以有效减小小轮径低地板驮背车直线段和曲线段的车轮磨耗,为抑制车轮磨耗,提升服役性能具有重要作用。

女性生理内裤优化设计与压力舒适性评价

以市售女性三角款生理内裤为基础进行优化设计,选取10名体态正常、穿着165/72A号型内裤的在校女大学生进行着装试验。使用柔性薄膜压力传感器测试系统测得受试者在站立、坐直、全蹲这3种日常姿势下各部位的压力值,并进行主观压力舒适性评价,采用CLO 3D软件进行内裤虚拟试穿以及压力分布模拟,通过主观评价、客观压力测试以及CLO 3D压力模拟验证生理内裤优化效果。通过SPSS软件进行主客观评价数据分析与模型建立,探究影响生理内裤穿着舒适性的关键因素。结果表明:优化后的生理内裤主观舒适度评分更高,内裤对下体的压力分布均匀,整体穿着舒适感更佳。

植物转印染工艺及其在女装中的实践应用

以植物转印染为研究对象,分析植物转印染的研究现状,介绍植物转印染的染色工艺。控制变量探索植物转印染在不同面料中的印染效果,探究植物转印染在女装设计中的应用形式。经过多次试验对比,寻找所设计女装最适宜的植物转印染面料,并制作成衣。