主动源与被动源面波勘探方法对比分析与应用

以福州地铁象山站勘探工程为背景,从瑞利面波基本理论出发,根据现场试验、工程实例及相关经验,对主动源面波与被动源面波勘探方法进行对比与研究,探讨各方法特点和工程应用特性,并综合主动源面波与被动源面波勘探各自的优势,更好地实现面波勘探方法在工程中的应用。     

Performance Limitations and Constraints for Active and Passive Suspensions: a Mechanical Multi-port Approach

This paper develops a framework using mechanical multi-port networks to study the performance capabilities and constraints in vehicle suspensions. We seek to understand the set of dynamic responses which are achievable for both passive and active systems. To this end, we view a suspension system as a mechanical multi-port network and draw on concepts from electrical circuits such as passivity and reciprocity. We identify necessary conditions on the external behaviour of a quarter-car model for the suspension to be capable of passive realisation, and thereby establish that several behaviours or force laws cannot be implemented without an internal power source. We study the number of available degrees of freedom (i.e., independently specifiable impedances) in the quarter-, half- and full-car cases.     

Performance Limitations and Constraints for Active and Passive Suspensions: a Mechanical Multi-port Approach

This paper develops a framework using mechanical multi-port networks to study the performance capabilities and constraints in vehicle suspensions. We seek to understand the set of dynamic responses which are achievable for both passive and active systems. To this end, we view a suspension system as a mechanical multi-port network and draw on concepts from electrical circuits such as passivity and reciprocity. We identify necessary conditions on the external behaviour of a quarter-car model for the suspension to be capable of passive realisation, and thereby establish that several behaviours or force laws cannot be implemented without an internal power source. We study the number of available degrees of freedom (i.e., independently specifiable impedances) in the quarter-, half- and full-car cases.     

中国载货汽车与国外的差距及发展方向

一、前言 我国从生产第一辆解放牌汽车开始,就与载货汽车结下了不解之缘.载货汽车在各行各业发挥了重要作用,为现代化建设做出了巨大的贡献.     

2014年俄罗斯卡车市场回顾

<正>2014年1 2月,前1 0大品牌在俄罗斯仅销售卡车8 900辆,较2013年同期减少24.4%;而2014全年,前10大品牌在俄罗斯的卡车销量比上年减少20.5%,只有11万辆。岁末年初,俄罗斯2014年卡车市场交出了惨淡的答卷。根据俄罗斯汽车统计分析机构的数据,2014年12月,前10大品牌在俄罗斯仅销售卡车8 900辆,较2013年同期减少24.4%;而2014全年,前10大卡车品牌在俄罗斯的销量比上年减少20.5%,只有11万辆。2014年12月,俄罗斯卡马汽车公司以及高尔基汽车公司的卡玛斯和嘎斯品牌一马当先,前者销售2 711辆,同比减少32.2%,而后者销售1086辆,但同比增加7.3%。位列第三的是白俄罗斯明斯克汽车公司的     

大型载货汽车被动安全性的特点及改进措施

大型载货汽车造成的人员死亡仅次于小型客车，工货汽车在交通事故中造成对方伤害的主要因素是：大载货汽车车架结构离地高度大，在前、后方造成轿车钻入碰撞、侧面造成展压，大型载货汽车的质量远大于轿车；与轿车时导致碰撞相容性问题，前、后下部防护装置能有效地防止轿车钻入，合理的能量吸收特性可改善载货汽车与轿车的碰撞相容性。中用交通事故统计数说明载货汽车被动安全性的重要性，深入分析载货汽车被动安全性的特点，最后介绍了改进载货汽车被动安全性的措施。     

2010年中国卡车市场回顾

一直以来,卡车市场变化受政策影响颇深。计重收费,轻量化车身受到追捧;排放标准升级,引领整车和关键零部件企业技术革新;4万亿元投资推动商用车市场,特别是卡车市场发展几近顶峰。2010年卡车行业处于强势增长态     

汽车主被动安全集成控制系统方案设计

在传统的汽车主动安全技术、汽车被动安全技术和国内外最新集成安全技术的基础上,提出了一种新的汽车主被动安全集成控制系统.对车辆行驶各种安伞状态下系统应具有的功能进行了分析.给出了实现汽车安全系统功能的多个关键技术模块的相互关系和实现思路,设计了汽车安全控制系统总布置及结构方案.然后,规划出汽车安全控制系统的控制功能定义层,对各种模式下汽车安全系统应实现的控制功能进行定义.最后,提出了基于分层控制结构的控制系统总体方案及其算法实现流程.     

玉柴重机宁夏市场见闻

举行用户座谈会:与用户、经销商面对面交流 在2010年玉柴营销服务年会上,玉柴晏平董事长勾勒出2010年玉柴经营战略,提出销售,售后,技术组合,即以销售为龙头,以售后,技术为依托和立足点的玉柴2010年的品字形经营战略.为了贯彻这一战略,2010年6月,玉柴在全国范围内开展了重机服务月活动.其间,不但有让利用户的各种优惠活动,如免费检查、保养、培训等,而且派出了由玉柴股份公司质量部、工程研究院、发动机一厂、发动机二厂、发动机三厂、铸造厂、销售公司等相关部门领导组成的7个工作组,远赴云南、四川、宁夏、湖南、广东等13个省区的市场一线,走访重点用户,了解市场需求,解决部分疑难故障.这对于用户来说,无疑是一大喜事.     

MathCAD在车辆主要性能计算中的应用

介绍MathCAD数学软件的特性及在车辆性能计算中应用的可行性,并以某越野车底盘主要性能的计算为例,说明了MathCAD用于车辆性能计算时直观、简单易用,以及计算、图形一体化等特点。     

重卡外气动性能评估与优化

利用数字仿真方法对某重卡的整车空气动力特性进行仿真分析。通过仿真分析,获得整车的风阻系数;并且根据对整车流场的压力云图分析,发现影响空气阻力系数的关键零件,并对导流罩进行了优化改进。优化后的分析表明改进效果是明显的,空气阻力系数得到了有效降低。     

Energy Requirements of a Passive and an Electromechanical Active Suspension System

Passive suspensions are designed to dissipate the energy otherwise transferred to a vehicle's body through interactions with a roadway or terrain. A bond graph representation of an independent suspension design was developed to study the energy flow through a vehicle. The bond graph model was tuned and validated through experimental tests and was found to produce suitable results. Examining the bond graph reveals that the dissipated energy associated with vertical and transverse coordinates generally originates from the longitudinal motion of the vehicle and is transferred through the tire-ground contact patch. Additionally, since the longitudinal energy originates from the vehicle's engine, the energy dissipated via the suspension shock absorber as well as other components (e.g., mechanical joints, etc.) essentially dissipate some engine energy. The plots presented in the paper support this theory by showing that upon traveling a rough terrain, the vehicle's longitudinal velocity drops more when vertical vibrations increase. Results show that a vehicle equipped with a passive suspension experiences a larger velocity drop compared to one with an active suspension traversing the same rough terrain. The paper compares the results of simulation of an analytical bond graph model of an active suspension system with experimental results and finds good agreement between the two. Other simulations show that relative to passive suspensions, not only do active suspensions yield substantial improvement in ride quality, they can also result in substantial energy savings. This paper concludes that if electromechanical actuators are supplemented by passive springs to support the vehicle static weight, the amount of energy required for operation of actuators is significantly less than the amount dissipated by conventional shock absorbers.     

Energy Requirements of a Passive and an Electromechanical Active Suspension System

Passive suspensions are designed to dissipate the energy otherwise transferred to a vehicle's body through interactions with a roadway or terrain. A bond graph representation of an independent suspension design was developed to study the energy flow through a vehicle. The bond graph model was tuned and validated through experimental tests and was found to produce suitable results. Examining the bond graph reveals that the dissipated energy associated with vertical and transverse coordinates generally originates from the longitudinal motion of the vehicle and is transferred through the tire-ground contact patch. Additionally, since the longitudinal energy originates from the vehicle's engine, the energy dissipated via the suspension shock absorber as well as other components (e.g., mechanical joints, etc.) essentially dissipate some engine energy. The plots presented in the paper support this theory by showing that upon traveling a rough terrain, the vehicle's longitudinal velocity drops more when vertical vibrations increase. Results show that a vehicle equipped with a passive suspension experiences a larger velocity drop compared to one with an active suspension traversing the same rough terrain. The paper compares the results of simulation of an analytical bond graph model of an active suspension system with experimental results and finds good agreement between the two. Other simulations show that relative to passive suspensions, not only do active suspensions yield substantial improvement in ride quality, they can also result in substantial energy savings. This paper concludes that if electromechanical actuators are supplemented by passive springs to support the vehicle static weight, the amount of energy required for operation of actuators is significantly less than the amount dissipated by conventional shock absorbers.     

某轻型载货车车架静动态性能分析

为了验证某轻型载货车车架静动态性能的可靠性,首先基于车架有限元模型对其进行自由模态分析,分析结果表明其固有频率处于激励频率范围之外,满足动态性能要求.然后对其进行模态试验,试验结果表明其仿真分析准确度较高,最后对其进行弯曲刚度和扭转刚度分析,分析结果表明其刚度值均符合工程要求.因此该车架的静动态性能具有较高的可靠性,符...     

汽车空气阻力和散热性能的仿真及优化

基于先进成熟设计理论,以降低汽车空气阻力和提高散热性能为目标,应用PowerFLOW软件,采用基于数字仿真分析结果与相关基本实验测试结果相结合的方法建立了仿真模型。结果表明,优化方法可以有效减少卡车空气阻力及提高散热性能。     

2015上半年俄罗斯卡车市场回顾

<正>2015年1-6月,前10大品牌在俄罗斯的卡车销量比上年减少46.6%,只有2万4 143辆。根据俄罗斯汽车统计分析机构的数据,2015年6月,前10大品牌在俄罗斯仅售出4 000多辆卡车,较2014年同期减少41.6%,但是较2015年5月环比增长25%。1-6月,前10大品牌在俄罗斯的卡车销量比上年减少46.6%,只有2万4 143辆。6月,俄罗斯卡马汽车公司的卡玛斯品牌以及高尔基汽车公司的嘎斯品牌,占据了前10大品牌卡车销量的前2位,前者销售1 345辆,同比减少34%,而后者销售788辆,同比增加7.9%。位列第三的是白俄罗斯明斯克汽车公司的玛斯品牌,销售266辆,同比减少57.3%。斯堪尼亚品牌排名第四,销售173辆,同比减少62%;曼品牌位居第五,     

主被动状态间墙体侧向位移与土压力关系

为了研究从静止到主动状态或从静止到被动状态下墙体侧向位移与墙背土压力大小的关系,以应力Mohr圆为出发点,通过引入内摩擦发挥角,推导了主动与被动状态间土压力与内摩擦发挥角的统一表达式。根据所构建的墙体位移与土体剪应变几何方程以及等极限应变下的剪应变-剪应力理想非线弹塑性物理模型,建立了能基本反映土体应力-应变特性和墙后填土初始应力状态的墙体位移-土压力统一函数关系式,并结合Coulomb土压力模型近似考虑了墙背与填土间摩擦力的影响。研究结果表明：影响墙体位移-土压力关系的核心要素是墙背初始应力状态、墙后滑移区范围及填土应力-应变特性;初始侧压力系数的增加,直接导致进入主动与被动状态所需墙体位移出现相应的增大和减小,墙体位移-土压力曲线沿水平轴呈现出整体平移的变化;土体内摩擦角和墙土摩擦角的改变会引起滑移区范围的变化,从而使墙体位移-土压力曲线整体放大或缩小;填土应力-应变特性是墙体位移-土压力关系的微观本质,其模量比与极限剪应变对墙体位移-土压力曲线的平缓程度及极限状态下的墙体位移大小影响显著。     

风扇布置对载货汽车散热性能的影响

为合理布置风扇以改善发动机舱散热性能,采用三维CFD方法,研究了怠速工况下风扇布置对载货汽车发动机舱散热性能的影响。冷却部件采用IRFM(intercooler,radiator,fan power train cooling module)布置方式。并就冷却风扇与主要部件间距离对散热性能的影响进行了仿真分析,结果表明,风扇和散热器距离越远,对发动机舱散热越有利;风扇与发动机本体之间存在一个最佳距离,使的发动机舱散热最好。