装载机铲斗几何形状的试验研究

本文通过对装载机铲斗模型的原理性试验和实形样斗的验证试验,探讨了装载机在铲装过程中插入阻力随插入深度的增加而变化的情况,研究了铲斗几何形状与插入阻力及满斗系数之间的关系。可为装载机设计提供参考。     

装载机振动式铲刃铲装土壤的初步探讨

装载机的铲装阻力,随铲斗插入物料深度增加而急剧增加,直至使变矩器失速或驱动滑转。这不仅严重影响动力性的发挥,而且由于变矩器经常处于低效区工作,传动效率低。采用振动作业方式,可大大降低作业阻力。本文对装载机振动式铲刃铲装土壤,进行了初步研究。试验结果表明,振动铲装可增加插入深度、降低插入阻力、提高作业生产率和经济效益。     

装载机铲斗设计新方法

铲斗是装载机工作装置的主要组成部件,装载机工作中既用铲斗直接切削、铲掘物料,又用它装载、运输和倾卸物料,所以铲斗的结构形状及尺寸参数对插入阻力、掘起力及生产率有着很大的影响。因此所设计的铲斗除应具有一定的容积外,还应具有合理的断面形状和较小的回转半径以保证较大的掘起力,较小的插入阻力及较大的满斗系数。装载机铲斗由前刃(有的装有斗齿)、侧刃、斗底、后壁、侧壁及后挡板焊合而成的斗形构件,它在车辆纵向断面的形状是不变的,所以铲斗的形状取决于断面的形状(如图1所示)。     

装载机铲斗斗齿数量对铲装性能影响的研究

针对装载机铲装碎石工况,通过安装不同数量的斗齿,对比铲斗铲装过程中作业阻力、最大插入深度和铲斗满斗率,分析斗齿数量对铲装性能的影响。结果表明:对于碎石物料,斗齿数量对作业阻力的影响不超过10%,对满斗率的影响不超过7.0%,对最大插入深度的影响不超过3.5%。如将本文研究扩展到更多工况,所获得的试验结果和经验,将有助于更合理地根据实际工况配装斗齿,且对斗齿的材料选择和寿命设计有很大参考价值。     

轮式装载机典型工况下铲斗铲装阻力实验获取方法

取原生土、大石方、松散土、小石方和半湿土5种作业物料,每种物料按一定比例的铲斗数进行实验。实验测试装载机动臂油缸压力,根据压力变化情况,把装载机的一个工作循环分为空载前进、铲掘、重载后退、重载前进及卸料、空载后退5个作业时段。实验测试各工作阻力消耗转矩曲线,折算后可以获得驱动力。根据装载机作业过程中力的平衡方程,获取典型工况铲掘作业时段铲斗工作阻力。与传统的根据经验公式计算获得的工作阻力相比,实验获取的铲斗工作阻力具有准确性和真实性的特点。工作阻力数字化后,可用于装载机动力性、燃油经济性虚拟仿真实验加载。     

智能装载机减阻插入铲取控制策略

本文阐述了智能装载机减阻插入铲取的思想。分析了铲斗的受力，在此基础上提出了一种减阻插入的方法，并对打滑的处理作了必要的说明。简述了一个智能减阻插入操作的工作流程。最后，介绍了本方法的应用情况。     

轮式装载机节能技术研究

<正>轮式装载机的作业循环中,物料铲装是其主要作业形式,整个作业循环包括以下4个工序:(1)以低速、直线驶向料堆,接近料堆时,放下动臂、转斗,使铲斗刀刃接地,铲斗斗底与地平面成3°～7°角,插入料堆。(2)铲斗以全力插入料堆,并间断地操纵铲斗转动和动臂上升,直至斗装满,把铲斗上翻至     

装载机反铲节能的可行性分析

在装载机工作装置上加装一个由微机控制的反铲装置,使铲斗铲掘物料能依靠反铲的作用,沿着被铲物料的滑动而自上而下将物料装满铲斗,从而使铲掘阻力最小。这种装置改变了装载机传统作业方式.达到节能,并减轻了操作劳动强度。     

装裁机反铲节能的可行性分析

在装载机工作装置上加装一个由微机控制的反铲装置，使铲斗铲掘物料能依靠反铲的作用，沿着被铲物料的滑动面自上而下将物料装满铲斗，从而使铲掘阻力最小。这种装置改变了装载机传统作业方式，达到节能，并减轻了操作劳动强度。     

十千牛级八角环及其测量系统的标定

装载机铲斗在铲装过程中的作业阻力,在正常情况下(正向作业、介质各向同性),其“强度”沿切削刃长度方向不变,而其切削刃的长度比铲斗的高度和深度都大得多。在这种情况下,可将铲装阻力简化为一平面力系(即所谓平面应变问题),因而可采用八角形二维测力传     

Study on shear resistance of aluminum alloy I-section members

The design method for the shear resistance of aluminum alloy I-section members is presented, taking into consideration of the post-buckling strength of webs and the restraint effect of flanges, and the practical design formulas are proposed. The deflection of aluminum alloy I-section members under concentrated load is simulated by using the finite element method, and several design theories are discussed. The relation of shear resistance to the maximum web displacement reflects that the web of aluminum alloy I-section member is under fewer shears buckling force, while the whole member has higher shear resistance. However, the traditional design method is not able to give the real shear resistance of aluminum alloy I-section members. The proposed design formulas for the shear resistance of aluminum alloy I-section members is used to calculate accurately the post-buckling resistance of webs and the shear resistance contribution of flanges. The results are in a great agreement with the test data of Hamoodi M J, Burt C A, Evans H R and the results from Eurocode9 formulas.     

空、实心钢管混凝土构件抗扭抗剪性能的研究Ⅱ:强度的理论研究

目前,钢管混凝土结构被大量应用和推广,但其剪切及扭转性能的研究都是从有限元分析或者试验出发,得出了回归公式或者经验公式,缺少纯理论上的指导。对钢管混凝土的抗扭承载力进行了理论研究,得到了抗扭承载力的理论计算公式;然后根据钢管混凝土"统一理论"的思想,得到了抗剪极限强度以及抗剪承载力的理论计算公式;最后与若干试验数据以及已有的研究成果进行了对比,证明了理论计算公式的可行性。     

预应力混凝土结构设计的综合内力法(一)——正截面抗裂计算

利用本文提出的综合内力法原理 ,可考虑次轴力和次弯矩的影响 ,采用预应力作用下的综合内力 ,推导出各类预应力混凝土结构抗裂实用设计公式 ,补充了现有规范的不足。本文公式简捷 ,便于实际工程应用 ,可适合各类预应力混凝土结构的抗裂设计验算。     

土层锚杆抗拔承载力确定方法及影响因素分析

利用现有的锚杆承载力计算公式对楠竹加筋复合锚杆和钢筋锚杆的极限承载力进行试算,结果表明,大部分公式对于楠竹加筋复合锚杆的计算结果偏大,而对传统的钢筋锚杆较适用。对以前的研究成果进行了总结,并在对各种土层锚杆承载力计算公式分析的基础上得出了影响锚杆抗拔承载力的因素,提出通过扩大锚杆截面和改良锚固方法可以提高锚杆抗拔承载力的工程建议。     

Study on shear resistance of aluminum alloy I-section members

The design method for the shear resistance of aluminum alloy I-section members is presented, taking into consideration of the post-buckling strength of webs and the restraint effect of flanges, and the practical design formulas are proposed. The deflection of aluminum alloy I-section members under concentrated load is simulated by using the finite element method, and several design theories are discussed. The relation of shear resistance to the maximum web displacement reflects that the web of aluminum alloy I-section member is under fewer shears buckling force, while the whole member has higher shear resistance. However, the traditional design method is not able to give the real shear resistance of aluminum alloy I-section members. The proposed design formulas for the shear resistance of aluminum alloy I-section members is used to calculate accurately the post-buckling resistance of webs and the shear resistance contribution of flanges. The results are in a great agreement with the test data of Hamoodi M J, Burt C A, Evans H R and the results from Eurocode9 formulas. __________ Translated from China Civil Engineering Journal, 2007, 40(3): 18–23 [译自: 土木工程学报]     

Wind turbine power curve estimation based on cluster center fuzzy logic modeling

Wind energy applications and turbine installation at different scales have been increased for last decade. Technically wind turbine capacity has been improved at high levels. However, electricity could not be generated at all stages of wind speed and so there are some limits related to cut-in and cut-out data. One of the main problems in wind engineering is to estimate output data of wind turbines depends on wind speed and system values. Wind speed problematic values, that are less than cut-in and greater than cut-out, take the most important role for estimating wind power curve models. All wind turbines have different cut-in and cut-out limits and generating of electricity could be achieved in a certain interval that could be called as affective interval. Fuzzy logic that is a new and novel verbal logical approach has many applications in the field of engineering. Cluster center fuzzy logic modeling is also a new and the effective method in this scientific area. In this paper, the first power curve of a wind turbine is modeled by least square methodology. After that depending on the fuzzy logic approach a new application is realized. It is seen that, this curve type could be well represented and modeled by the clustering center fuzzy logic modeling than classical least square methodology. It is estimated that four or five cluster centers are enough for representing wind turbine power curve by running proposed method.     

超长R·C·框架梁板结构温度及收缩钢筋计算

介绍了一种有关温度及收缩内力计算的近似公式,并以规范裂缝宽度公式为基础,推导出可用来判断R·C·框架梁板结构各部分是否超长的温度及收缩界限内力公式;对超长者,给出了温度及收缩钢筋的计算公式和配筋建议,从而为其抗裂设计提供了一条有效途径和计算依据。     

预应力型钢混凝土框架梁试验研究及抗裂度分析

基于两榀大尺度后张有粘结预应力全型钢混凝土框架的静力试验,对预应力型钢混凝土框架梁的抗裂度进行了测试和理论研究。应用混凝土基本原理、GB 50010—2002《混凝土结构设计规范》和ACI318—05规范中抗裂度公式推导了考虑次轴力的预应力型钢混凝土框架的抗裂度计算公式,用试验值进行验证。结果表明：按照混凝土基本原理推...     

浅谈辽沈地区静压桩沉桩阻力的估算

针对辽沈地区岩土工程的特点,选择了三个具有代表性的已有计算沉桩阻力的公式进行分析研究,以期找出适合该地区的沉桩阻力计算公式,进而对采用静压桩施工工艺、判断沉桩可能性和施工设备的选型具有重要的参考价值。     

端部嵌固桩的稳定性分析

对 3种不同的桩顶支承情况下的端部嵌固桩 ,用能量法对其在顶部集中荷载和桩侧摩阻力作用下的竖向稳定性进行了研究 ,推导了求解失稳问题的计算公式 ,用数值方法求得了桩的临界长细比的数值解。通过对数值解的分析 ,最后得到桩的临界长宽比简单的近似计算公式