新型装载机工作装置受力及有限元分析

以新式的八连杆工作装置的装载机为研究对象,建立力学模型,利用有限元方法对其动臂进行性能分析。取其偏载工况为例,计算出动臂在极限偏载情况下各个铰接点的受力情况,通过有限元分析得出动臂的应力分布云图及变形图,并找出动臂的危险点和应力集中区域,在结构设计和加工工艺中予以重视,为改进设计提供依据,对装载机工作装置的设计有一定的指导意义。     

基于电子技术的装载机铲斗设计

当前工程机械的先进技术大部分集中在操纵和控制上,要解决控制问题必须引入具有良好控制性能和信息处理能力的电子技术。本文主要研究基于电子技术的装载机铲斗设计,使装载机的操作更为简单。电控装载机铲斗采用电液比例控制系统来控制装载机的转斗油缸,通过动臂转角和铲斗相对动臂转角的反馈来自动控制铲斗的角度,实现自动平移。选用复合形法编写优化程序,结合装载机工作装置的数学模型对工作装置进行优化设计,而且基于电控的优化能获得更大的传力比。     

基于弯矩等效的装载机外载荷当量与载荷谱编制

为了编制装载机工作装置载荷谱进行结构疲劳性能研究,提出了一种基于动臂截面弯矩等效的装载机外载荷当量方法,将装载机铲装物料时所受外载荷简化为一个作用在铲斗上的集中载荷并进行载荷谱编制。以动臂前后两端铰点连线为基准构建动臂局部坐标系,将铲斗铰点实测载荷转化为局部坐标系下动臂铰点载荷,研究铲掘姿态下动臂截面弯矩和装载机外载荷的同步对应关系,确定了外载荷作用点位置和作用方向,利用动臂最大弯矩截面的弯矩等效建立了装载机外载荷的当量数学模型。由实测的铲斗铰点载荷时间历程和装载机外载荷当量模型得到ZL50G装载机当量外载荷的时间历程,采用雨流计数得到典型作业介质下当量外载荷均值、幅值、频次的统计特性,编制多工况合成的工作装置疲劳试验程序载荷谱。结果表明:基于动臂截面弯矩等效方法能够获取固定姿态下装载机当量外载荷作用位置和作用方向;利用动臂最大弯矩截面的弯矩得到当量载荷时间历程,且在当量载荷与实测载荷下动臂截面弯矩变化规律和大小保持一致;当量载荷均值服从正态分布、幅值服从三参数威布尔分布,利用雨流计数和参数外推法编制的适用于工作装置疲劳试验的变均值加速加载程序载荷谱,缩短了疲劳台架试验的加载时间。提出的基于动臂截面弯矩等效的装载机外载荷当量模型以及载荷谱编制方法,可为装载机工作装置疲劳寿命评估和台架试验规范的制定提供依据。     

双伸缩臂装载机动臂的有限元分析

论述了双伸缩臂装载机工作装置的结构特点，建立了工作装置动臂的有限元计算模型，并应用线弹性结构分析程序ＳＡＰ５Ｐ对它进行强度和刚度研究，研究结果已用于结构设计。     

ZL-50型轮式装载机工作装置、车架疲劳强度试验研究

“ZL-50型轮式装载机工作装置、车架疲劳强度试验研究”课题属机械工业部重点科研项目“轮式装载机关键部件和关键技术研究”中一个子项的一项。动臂、车架是装载机的重要结构件,它们的疲劳寿命如何?将直接影响到装载机的工作可靠性和使用寿命。此项研究对提高装载机设计水平、产品质量、保证产品的可靠性和耐久性有着重要意义。 课题应用先进的疲劳载荷谱和室内模拟疲劳试验技术,对ZL-50型装载机的动臂、车架进行了静载、动载测试,编制了疲劳载荷谱和试验谱,并在电液伺服结构疲劳试验机上首次对后车架作了疲劳试验,都取得了良好的结果。 1.初步摸清了ZL-50型装载机动臂和车架在静载及动载作用下的受力情况、应力     

木材装载机单板动臂的强度分析与结构设计

<正>装载机动臂的强度直接关系到整机的使用性能和寿命。中型木材装载机的动臂通常采用箱型结构。为了适应生产的发展,我们改用单板动臂并采用现代设计法进行精确的强度分析和结构设计的研究。本文为中型木材装载机改用单板动臂提供了可靠的依据和科学的设计方法。     

基于虚拟样机的轮式装载机开发技术研究

轮式装载机传统开发模式需要经过样机设计、制造、测试、改进等循环过程,存在试制周期长、开发成本高等问题.提出轮式装载机虚拟样机的开发策略,构建虚拟样机的开发平台,研究相关软件的数据交换方法.采用Pro/E创建轮式装载机的实体模型,构建虚拟样机,在ADAMS环境进行仿真研究,利用ANSYS对动臂总成进行了有限元分析,完成了轮式装载机虚拟样机开发的系统性研究.     

装载机工作装置液压系统常见故障分析与排除

装载机工作装置液压系统的故障主要表现为:动臂举长缓慢,无力或无动作;铲斗翻转无力或无动作.     

装载机工作装置的疲劳试验及疲劳可靠性评估

为了对装载机工作装置进行抗疲劳设计和疲劳可靠性评估,在获得ZL50G装载机工作装置固定姿态当量外载荷二维载荷谱的基础上,对载荷谱进行了等寿命加速处理,设计疲劳试验台进行加速加载疲劳试验研究,并对工作装置进行了极小子样疲劳可靠性评估。结果表明:利用加速加载谱加载35.88 h可以等效装载机连续作业495.67 h,实现了工作装置快速疲劳试验的目的;工作装置试件的实际疲劳寿命的平均值为9 132.20 h,疲劳破坏起始于销轴衬套与动臂焊接处,靠近动臂板处的焊趾裂纹源是造成疲劳断裂的主要因素;基于给定工作寿命和疲劳寿命试验结果的极小子样疲劳可靠性评估,获得了工作装置寿命与可靠度为3次多项式的数学关系。     

装载机工作装置液压系统常见故障分析与排除

装载机工作装置液压系统的故障主要表现为:动臂举长缓慢,无力或无动作;铲斗翻转无力或无动作. 　　1 动臂举升故障 　　造成动臂举长故障的主要原因应是工作油压偏低.在测压点接表,系统憋压,可直接测出其实际工作压力,如果系统压力偏低,应主要从以下几个方面分析: 　　……     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that