Study of engaged performance regulation in controlled transfer clutch of 4WD car based on genetic sliding mode control

This paper investigates an approach to improve the engagement quality of controlled transfer clutch mode in 4 wheel drive(WD) car from three considerations of reducing friction,smoothening responsiveness and alleviating jerk.The method utilizes an improved sliding mode control with genetic algorithm instead of simplified mode to determine appropriate values of parameters in control close- loop.The simulation results show that the method is effective for improving the engagement quality of coupling satisfying different design needs for 4WD car,as well as robustness even if input torque is changed at a certain range.

Research on application of plastic materials in cars

This paper gives analysis of application status and prospect of plastic materials from the aspects of applied material amount comparison,development of new materials & new technologies,lightweight,design conception of new components,recyclability,simplification and diversity of materials,standardization of material specification and presents corresponding conclusions and suggestions.

热冲压成形钢的研究进展

对普通热冲压成形钢,高淬透性、高抗氧化性热冲压成形钢,高强韧性热冲压成形钢,超高强度热冲压成形钢,高抗氢脆敏感性热冲压成形钢,纳米粒子强化超高强度热冲压成形钢等热冲压成形钢近年来的发展概况进行了综述,分析了热冲压成形钢零件轻量化与功能性的关系,强度与氢脆之间的关系,以及组织细化对其强韧性的影响机理,并对热冲压成形钢今后的发展方向提出了建议。

汽车车身用铝合金板材的研究现状

可用于汽车车身的铝合金板材主要包括2000系、5000系和6000系合金。从汽车车身用铝合金板微合金化及热处理、车身用铝合金板的先进成形技术和车身用铝合金板的有限元研究3个方面介绍了汽车车身板用铝合金的研究现状。

汽车用LFT前端框架的开发和应用

针对某乘用车钢制前端框架和技术性能要求,通过长纤维增强热塑性复合材料(LFT)机械性能对比分析,结合LFT前端框架生产工艺和制造成本,确定选用PP-LGF30粒料进行LFT前端框架开发。通过汽车前端框架集成设计,对多目标优化设计后的结构,进行了模流分析,确定了最终设计方案。基于零件3D图,开发了模具,应用注塑成形的方法试制了LFT前端框架,对试制件进行了多项台架测试和整车匹配验证。结果表明:各项指标达到使用要求,LFT前端框架相比传统钢制件,减重比例达到56%,取得了良好的轻量化效果。

热成形钢及热冲压零件的氢致延迟断裂

超高强度钢的开发和应用是汽车轻量化和提高安全性的重要途径,1500 MPa及更高强度的高性能热成形钢的开发和应用是关键,超高强度热成形钢及热冲压零件的氢脆风险必须要重视并且避免。介绍了氢脆现象的发现、氢脆的概念、氢脆的机理,并试图用氢致局部塑性增加及晶界脱聚相结合的机制来解释热成形钢的氢脆开裂现象,进而综述了抑制氢脆的方法和采用铌微合金化抑制氢脆的试验结果,并根据氢增强局部塑形(HELP)和氢强化脱聚效应(HEDE)的耦合氢致延迟断裂机制说明了铌微合金化提升氢致延迟断裂抗力的原因。

铌钒微合金化对22MnB5热成形钢显微组织与性能的影响

复合添加质量分数均为0.04%的铌和钒对22MnB5热成形钢进行微合金化,对比研究了微合金化前后试验钢的显微组织、拉伸性能、淬透性和极限尖冷弯性能,分析了铌钒微合金化对性能的影响机制。结果表明:微合金化前后试验钢的显微组织均为全马氏体且均存在明显的马氏体板条束,微合金化后的组织更为细小,马氏体板条束长度更短,拉伸性能略有提升;铌钒复合微合金化能有效提高试验钢的淬透性,其淬硬层深度由未微合金化的3～5mm提高到13～14mm;铌钒微合金化后试验钢的极限尖冷弯角为65°～70°,显著高于未微合金化的;NbC细化晶粒与VC沉淀强化的协同作用是微合金化后试验钢具有更优性能的根本原因。

微合金化热成形钢开发应用进展及展望

超高强钢是汽车实现轻量化兼顾安全性的关键材料,1.5GPa及以上高性能热成形钢的开发和应用是关键。近10a来,微合金化热成形钢及其零件制造技术迅速发展,实现了高弯曲角度、抗氢脆断裂、高韧性、高淬透性等性能目标,进而提高了车辆的被动安全性能及轻量化水平。综述了微合金化热成形钢开发与使用现状,包括1.52.0GPa级铌、钒、铌钒复合、铌钒(钼)复合微合金化热成形钢的开发和应用进展,以及微合金化对纳米级第二相析出和晶粒细化的影响;微合金化热成形钢的抗氢脆性能和机理;微合金化热成形钢的尖角冷弯性能及其对碰撞安全性能的影响;微合金化热成形钢的断裂失效性能。对今后微合金化热成形钢的生产制造与应用前景作出展望。

重型汽车钢板弹簧早期断裂原因

某重型汽车51CrMnVA钢板弹簧(板簧)预压后在冬天放置时发生断裂,通过断口分析、显微组织观察、力学性能测试、与正常服役后失效板簧进行对比等方法对其早期断裂原因进行了分析。结果表明:由于回火温度偏低,该板簧强度和硬度偏高,韧性偏低,加之钢中可扩散氢含量和预压变形应变速率过高,板簧在低温下发生脆性断裂;降低钢中可扩散氢含量,提高回火温度,延长回火时间,增加氢陷阱数量,得到适当的强韧性匹配,可有效避免板簧的早期失效和氢致延迟断裂。

Nb合金化对22MnB5热成形高强钢点焊性能的影响

22MnB5热成形高强钢的Nb合金化可细化晶粒、提高强韧性,但Nb合金化对其电阻点焊性能的影响尚需进一步探明。本工作设计、制备了22MnB5、22MnB5Nb热成形钢的点焊试样及等效热处理试样,并对试样组织性能进行了测试。研究发现,对于点焊试样,Nb的添加细化了焊点区域的晶粒,拉伸峰值载荷有所降低(降幅在7%以内),焊点硬度范围缩窄,但未改变失效模式以及焊点各区域材料组织类型;对于等效热处理试样,Nb的添加同样细化了晶粒且未改变焊点区域的组织类型,但对试样硬度和抗拉强度的影响很小,断后伸长率普遍有所降低。

高性能微合金化热冲压成形模具用钢服役性能的影响

针对目前在1000 MPa级以上超高强度工业零件制造领域广泛使用的热冲压成形专用热作模具应用需求,为提高其在服役过程中的抗磨损、抗热疲劳性能,在传统热作模具钢合金体系基础上,开发出一种微合金化的热成形专用模具钢.研究结果表明:新开发模具钢屈服强度≥1400 MPa、抗拉强度≥1700 MPa、延伸率≥11%、强塑积≥20 GPa%、冲击功≥50 J,强塑性水平优异.与传统的H13模具钢相比,新开发钢种是通过控制Nb的碳化物和V的碳化物的析出量来获得更强的韧性、抗磨损性能、抗热疲劳性能及更稳定的导热系数,拥有更优异的综合服役性能.采用新开发钢种制造的热成形模具使用寿命为50万~60万次,达到国内领先水平.微合金化促进组织细化,实现组织强化,提升组织的热稳定性是新开发模具钢具有优异服役性能的根本原因.

铌微合金化热成形钢的最新进展

结合作者的近期研究结果以及业界同行的研究,从乘用车和商用车应用两个角度,对1500~2000 MPa铌微合金化的热成形钢开发及性能研究进展进行了总结分析,发现当Nb含量(质量分数)>0.03%时,钢材晶粒细化显著,晶粒尺寸可以达到传统热成形钢晶粒尺寸的1/3~2/3,甚至更小;在传统的热成形钢中添加Nb或者复合添加后,纳米析出相尺度主要为1~30 nm,而且平均尺度在10 nm左右。铌微合金化通过抑制了氢脆的4个触发条件,进而有效降低热成形钢及零部件的氢脆风险。铌微合金化使热成形钢的尖角冷弯角度提高了10%~15%,可以使零件断裂指数提高45%~80%,铌微合金化热成形钢在应力三轴度(-0.6~0.4)状态下临界断裂应变更高,提高热冲压成形零件的抗碰撞断裂能力。铌微合金化热成形钢在乘用车和商用车上的应用可以有效减低减轻质量,实现轻量化,并提高安全性能。

汽车EVI技术进展

阐述了EVI的概念、目的及意义,综述了热成形钢、淬火分配(Quenching and Partitioning,QP)钢及DH钢冷成形钢、和新能源汽车专用的高强度钢硅钢新材料方面的进展,以及可实现高精度碰撞模拟的材料断裂卡片和实现剪切边缘冲压模拟的材料成形卡片的开发进展,论述了在新材料开发和精准成形及碰撞模拟的基础上的乘用车车身正向选材,实现EVI的核心目标之一“合适的材料用在合适的地方”。探讨了热成形门环、一体化铝合金下车体、商用车热成形上装及车轮最新制造工艺技术。分析了“双碳”和“抗氢脆”两个共性需求,并提出了低碳排放汽车钢及铝合金零件的实施路径,以及抗氢脆热成形钢和冷成形钢的实现路径。对原材料企业和零部件企业当前和未来基于EVI技术和服务方向提出了建议。

Research progress of aluminum alloy automotive sheet and application technology

Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author＇s knowledge and recognition and research progress presently, the important re- search contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.

On the automobile lightweight

The significance,description parameters,evaluation method,implement way and design for lightweight of automobile are comprehensively reviewed.The relationship among the performances of auto parts & components,the properties of materials and application of advanced technologies is also elaborated.According to recently related progress of lightweight and authors' research and developing work,lightweight of automobile is comprehensively and systematically overviewed.

Analysis of surface orange peel of aluminum-alloy automobile sheet by using of EBSD and X-ray diffraction

The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.

Research status and progress of hot stamping

In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are described.The survey of existing works,especially key equipments has revealed several gaps.Some new ideas and programs are proposed on the basis of traditional process.This article aims at providing an insight into a whole process backgrounds and pointing out the great potential for further investigations and innovations of hot stamping.

Numerical simulation of hot stamping of side impact beam

Ls-DYNA software is adopted to conduct research of numerical simulation on hot stamping of side impact beam to calculate the temperature field distribution, stress field distribution, forming limit diagram （FLD） figure, etc. in the course of hot stamping so as to predict and analyze the formability of parts. ProCAST software is employed to conduct research of numerical simulation on solid quenching course concerning hot stamping to calculate temperature field distri- bution of tools and component of muhiple stamping cycles. The results obtained from numerical simulation can provide significant reference value to hot stamping part design, formability predication and tools cooling system design.

Morphology observation for surface orange peel and fracture in tension sample of aluminum-alloy sheet and characterization of nano hardness

The tension property of aluminum-alloy sheet with different microstructures is measured, and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning electron microscope （SEM）. Surface roughness and nano hardness of tension sample are measured. The results show that the average elongation of the samples with orange peel is lower than that without orange peel ; especially the r value of per- pendicular to the rolling direction is much lower than that without orange peel. The tension surface of the orange peel samples is very rough; various parameters of surface roughness are higher. Under the observation of SEM, a wider slid- ing band with a micro crack on the surface of orange peel sample can be found. The various parameters of surface rough- ness without orange peel sample are near to zero, the sliding band is narrow and without micro cracks. The dimple width in tensile fracture of orange peel sample is larger than that without orange peel sample, but shear lip is narrower. The nano hardness testing results show that samples with orange peel behave high elastic modulus, high hardness, and high maximum load, but low plastic deformation depth. These mentioned features can completely describe surface and frac- ture morphology of tension samt31es with oranze peel.

Study on the resistance spot welding technology of 22MnMoB hot stamping quenched steel

In this paper, the spot welding technology of a new kind of 22MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder. Through a series of technology and test experiments, we have obtained the optimal spot welding technological parameter condition. According to the results, the relations among spot welding technological parameter, welding nugget, mechanical property and fracture mode were discussed. The effects of all the welding parameters such as welding current, welding time and electrode force on the quality of joint can be boiled down to one thing--the diameter of welding nugget. The experimental results showed that welding nugget diameter determines the mechanical property of spot welding joint and the relation between welding nugget diameter and the mechanical property of joint presents a kind of linear mathematic representation. There are two typical fracture models of 22MnMoB hot stamping quenched steel sheet, i.e., interracial fracture and nugget pullout. Other than mild steel or normal high strength steel, in the shearing tensile test, hot stamping quenched steel has a great tendency to fail in interfacial mode due to the effects of high strength matrix structure, welding soft zone and the porosity level of fusion zone.