Operator health risk evaluation of off-highway dump truck under shovel loading condition

To evaluate the operator health risk exposed to whole-body vibration(WBV) while the electric-shovel loads the ore on the truck body, the semi-truck mathematical model and 3-D virtual prototype were built to simulate the high shockwave of truck cab under the shovel loading. Discrete element method was utilized to accurately estimate the impacting force on the truck body. Based on the ISO 2631-5 criteria, the Sed is about 0.56 MPa in both models, which means that the dump operators have a high probability of adverse health effects over long-term exposure to these vibrations. The 4-DOF operator model was built to investigate the biodynamic response of seated-human body exposed to WBV in terms of the transmission of vibrations through the body. The results show that the response peak is in the frequency range of 4-6 Hz corresponding to the primary body resonant frequency.

Economic Impact of Higher Timber Truck Loads on Louisiana Bridges

Due to the limited amount of funds available for bridge inspection, maintenance and rehabilitation, the evaluation of load capacity for existing bridges is crucial to the Louisiana Department of Transportation and Development. This paper includes the development of a methodology to assess the economic impact of overweight vehicles with permits, hauling Louisiana harvest products on state bridges. The proposed higher truck loads are applied on the existing bridges and their effects are determined using deterministic load capacity evaluations as well as reliability assessments. The target rehability level is derived from bridge structures designed to satisfy AASHTO Standard Design Specifications and also satisfy safe and adequate performance levels. The amount of harvest produced is used to select a representative sample of bridges to provide specific examples of expected changes in load ratings and safety levels. The bridges include simple and continuous span behavior. Strength and serviceability criteria are investigated under current legal loads and the expected changes, due to the proposed new weights, are determined. The results are used to assess the cost of crossing a bridge and the permit fees for the proposed truck weight regulation.

Investigation of Excavator Performance Factors in an Open-Pit Mine Using Loading Cycle Time

This study presents the effect of excavator model, loading operation location, shift availability and truck-shovel combination on loading cycle time and productivity of an open-pit mine. The loading cycle time was used to assess the material loading system performance which is one of the key components of the total cycle time for material transportation in an open-pit mine. Loading is among the components of cycle time during which material is being handled. The data analyzed?was?collected from a computerized dispatch system at GGM from which 62,000 loading dispatches per month involving several shifts, 14 excavators and 49 trucks were loaded. About 4465 dispatches per excavator and 1276 dispatches per truck were assessed using loading cycle time data for each dispatch for a period of four months (between August and December). Under fixed tonnage loaded and waste type (33 t of non-acid forming waste rock),?it was observed that loading cycle time depends on excavator model, location and truck being loaded. Average cycle times, PDFS?and CDFS of loading cycle time series were used to identify differences in performance under different situations. It was concluded that shift availability for excavators, loading location, excavator model and truck-shovel combinations strongly affect the productivity during loading process in an open-pit mine.

Performance analysis of air suspension system of heavy truck with semi-active fuzzy control

In order to analyze and evaluate the performance of the air suspension system of heavy trucks with semi-active fuzzy control, a three-dimensional nonlinear dynamical model of a typical heavy truck with 16-DOF（degree of freedom） is established based on Matlab/Simulink software. The weighted root-mean-square（RMS） acceleration responses of the vertical driver ＇s seat, the pitch and roll angle of the cab, and the dynamic load coefficient（DLC） are chosen as objective functions, and the air suspension system is optimized and analyzed by the semi-active fuzzy control algorithm when vehicles operate under different operation conditions. The results show that the influence of the roll angle of the cab on the heavy truck ride comfort is clear when vehicles move on the road surface conditions of the ISO level D and ISO level E at a velocity over 27.5 m/s. The weighted RMS acceleration responses of vertical driver＇ s seat, the pitch and roll angle of the cab are decreased by 24%, 30% and 25%, respectively,when vehicles move on the road surface condition of the ISO level B at a velocity of 20 m/s. The value of the DLC also significantly decreases when vehicles operate under different operation conditions. Particularly, the DLC value of the tractor driver axle is greatly reduced by 27.4% when the vehicle operates under a vehicle fully-loaded condition on the road surface condition of ISO level B at a velocity of 27.5 m/s.

Study on Truss Robot Structure of Refrigerator Automatic Loader

Aiming at the requirements of intelligent loading and shipping in large household appliance industry,an automatic loading and unloading robot for refrigerator is proposed.The robot is a gantry truss robot,which is composed of active support,passive support,beam and fixture components at both ends to realize the taking and placing of the refrigerator on the logistics transmission line to the truck.In the actual working conditions,the no-load truss robot experiment,found that the robot in the design problems,and the robot was optimized.It not only solves the safety hazards of the refrigerator when grabbing and stacking products,but also realizes the automation and intelligence of the refrigerator conveying process.

Timber Trucking Characteristics in Greece

Wood transportation begins from the landing or the forest road where the processed wood assortments are placed, they are loaded on trucks and then transported to the wood-working industry and/or the consumption centers. Wood transportation in Greece is carried out, almost exclusively, by trucks. The aim of this study is to analyze the evolution of timber trucking in Greece through the analysis of wood transportation waybills. A total of 1,471 waybills have been collected and analyzed that cover the period 1981-2008 from nine of the most productive and representative forest districts in Greece, in terms of timber production. The final dataset included information on the type and technical characteristics of truck types, the transported wood quantities and haulage distances. Furthermore, data on the wood transportation cost for the year 2010 have been collected and analyzed. According to the results, the number of two-axle trucks that dominated in the 1980s is reducing rapidly, mostly to the benefit of larger three-axle and four-axle trucks. More than three quarters （77%） of wood transportation is conducted in the period June-October. Mean vehicle load per vehicle type differs between conifer and broadleaved species from 7.1% up to 23.9%. Transportation of stacked wood with semitrailers is conducted with overloaded trucks, which could entail serious problems for public safety and the condition of road network. New design standards will enhance serviceability of the wood transportation routes and environmental protection.

一种基于曲率和B样条的矿区装载车辆连续路径规划方法

矿区装载车辆的任务是从进入点到装载点进行装载,然后离开矿区。在进入装载点前,车辆要在回转点改变行进方向,以便倒车进入装载点。针对装载车辆的任务特点,本文提出了一种基于曲率和B样条的路径规划方法。首先,基于车辆运动模型设计了A*算法的成本函数,获得了与车辆转弯半径相关的离散路径。为了进一步获得装载车辆的连续路径,又提出了改进的B样条插值法,使得连续路径两端切线符合车辆起始点和终点的位姿。随后,基于模拟退火算法,获得了车辆的回转点,使得车辆可以在进入装载点前改变前进方向。仿真结果表明,所提出的连续路径规划方法能够保证生成曲率连续的装载车辆路径,并保证路径两端符合车辆在起始点和终点的位姿,为矿区装载车辆的自动驾驶技术提供了基础。

大型矿用自卸车厢斗装载程序分析及力学特性研究

自主装卸是智能矿山建设中亟待突破的关键技术,电铲-矿用自卸车合理的装载程序能够显著降低电铲装卸作业难度,降低复杂动态载荷对厢斗力学性能的影响。以某型号矿用自卸车厢斗为研究对象,依据厢斗容量标定方法建立了厢斗的堆装模型,确定厢斗堆装容积;分析了厢斗安装特点及结构特征,结合现场实际装载经验,提出了三种不同的装载程序,并利用离散元方法对三种装载程序进行仿真分析,研究不同装载程序下厢斗装载量、物料均匀性及底板承受的压力等;在此基础上,通过仿真分析研究厢斗满载工况下的力学特性。结果表明,在厢斗装载过程中将装载位置放在厢斗满载重心及前侧位置可提升装载量,各铲装载位置尽量靠近厢斗横向方向的中轴线,本文提出的装载程序二的装载量最大,物料可通过自身堆积特性装满厢斗,并在厢斗内部的均匀性更好,且物料装满后厢斗底板的总压力最小,当满载后厢斗的最大变形量为7.50 mm,最大应力为326.85 MPa,满足刚度、强度设计要求。

基于实测数据的货车编队荷载作用特征分析

货车编队技术是货运交通智能化的重要研究方向之一。以货车编队的荷载作用为研究对象,在明确货车编队的横向、纵向控制模式的基础上,调研并总结了国内外货车编队的实测项目;基于AUTOPILOT项目的实测数据,分析了货车编队的横向和纵向荷载分布特征,并在此基础上分析了货车编队的轴载作用影响。结果表明:货车编队的轮迹横向分布标准差为7.14 cm,仅为传统货车的1/3,具有明显的“渠化”特征;货车编队在以100 km/h的速度行驶时,车头时距可低于0.8 s,约为相同速度下传统货车的27%;与传统货车相比,货车编队运行轴载作用次数具有“高频”特性,对现有路面结构的抗疲劳性能提出更高的要求。

超重型消防车地下室顶板荷载等效取值研究

目前国内各大城市均有采购多辆101 m登高平台消防车(63 t),其重量远远超过了《建筑结构荷载规范》(GB 50009—2012)中原型消防车的重量(30 t),《建筑结构荷载规范》(GB 50009—2012)未对此类消防车给出具体的等效均布荷载取值。以101 m登高平台消防车(63 t)为研究对象,首先通过绘制板的跨中弯矩影响面来确定其最不利位置,然后利用ABAQUS计算出2种荷载工况下板的跨中弯矩值,最后再等效出101 m登高平台消防车(63 t)分别在7 m×7 m、8 m×8 m、9 m×9 m双向板的荷载取值。结果表明:板跨大于6 m的地下室双向板消防车荷载不建议直接取规范值,可按照设计需要采用相应流程进行等效;若对地下室顶板设计精度要求不高,当双向板板跨大于8 m时,63 t级消防车可参照规范要求进行荷载等效。

基于高阶马尔可夫链的纯电重卡集群负荷预测

相比于普通电动汽车,纯电重卡具有更高的充电功率、更大的电池容量和更可观的调度潜力,同时受货物重量、物流特性及行驶路径等诸多因素影响,其充电负荷呈现更大的随机性,建立准确的纯电重卡集群负荷预测模型有利于掌握其充电规律,降低对电网的冲击。为此,提出了考虑物流特性基于高阶马尔科夫链的纯电重卡集群负荷预测方法。首先,在考虑软时间窗约束实现纯电重卡路径规划的基础上,通过分析纯电重卡行驶特性预测其开始充电时间,以获取各时刻纯电重卡充电数量;其次,对纯电重卡的荷电状态区间进行模糊双层离散化分区处理,将每个大区间进一步细分为n个小区间,提高预测精度;然后,在求取纯电重卡荷电状态多步转移概率基础上,采用高阶马尔可夫链建立集群负荷预测模型,实现更为精确的负荷预测;最后,采用某物流园区实际纯电重卡数据进行仿真验证,结果表明,所构建的负荷预测模型较准确地预测了纯电重卡集群功率,同时减小了普通马尔科夫链方法的预测误差。

零担物流时序预测的SARIMA-GRU-BPNN组合模型及应用

针对零担物流的需求物流量显著季节性、非线性和随机性特征使其预测难度大的问题,提出一种零担物流时序预测的SARIMA-GRU-BPNN组合模型的预测方法。使用季节性分解模型将物流量分解为趋势、季节性及残差,对趋势分量采用季节性差分自回归移动平均模型(SARIMA)拟合线性变化,对季节性分量采用门控循环神经网络(GRU)拟合季节性变化,对残差分量采用反向传播神经网络(BPNN)拟合非线性及随机性变化,组合重构得到最终预测值。实验结果表明,与自身单一模型SARIMA、GRU及BPNN相比,均方根误差(RMSE)分别降低31.5%、34.5%及47.1%;与其他单一模型灰色模型、支持向量机、长短期记忆网络及多元线性回归相比,RMSE分别降低71.3%、68.9%、54.4%及70.7%;与组合模型ARIMA-GRU、ARIMA-BPNN及ARIMA-SVM相比,RMSE分别降低31.0%、43.0%及56.1%,且趋势和季节性分量预测模型拟合优度达到92%和99%,有效降低整体预测误差,提升了预测精度和模型稳健性。

数据驱动的混凝土泵车臂架疲劳载荷谱编制

为对混凝土泵车进行疲劳分析,利用大数据分析技术,提出了一种数据驱动的混凝土泵车臂架疲劳载荷谱编制方法。通过分析臂架倾角和夹角定义了混凝土泵车典型作业姿态。根据所选取的典型作业姿态进行载荷信息采集,并对采集到的原始信号进行了数据预处理,以提高数据质量,令之后的疲劳载荷谱编制更具可靠性。采用参数法对测试载荷谱的幅值分布进行了参数估计和外推,以获得全寿命周期下的载荷谱,并用强化后载荷谱进行了疲劳验证。通过对300多台某型号混凝土泵车所采集到的大量数据进行试验验证了所提方法的可靠性和工程实用性。该研究成果为混凝土泵车多关节臂架结构疲劳载荷谱编制提供了参考。

重卡桥壳轴向环向补料液压胀形内压加载路径的确定

轴向环向补料液压胀形变形过程复杂,合理的加载路径确定困难,成形时易发生失稳起皱及胀裂。通过变形分析,揭示了轴向环向补料液压胀形两个阶段各典型位置发生变形所需内压的变化规律,确定了线性增压—恒压—线性降压的加载路径,推导出各阶段的内压计算公式,给出了上控制模平面高度与最大扩径量的关系。针对某载荷10 t重卡桥壳,通过有限元模拟及工程试验验证了加载路径的正确性,揭示出加载路径线性降压段的降压系数、上控制模高度系数对管坯成形质量的影响,确定了二者的合理范围,消除了失稳起皱及开裂的隐患。

装载冲击下矿用自卸车油气悬架减振特性分析

油气悬架具有良好的缓冲减振作用,被广泛应用于矿用工程车辆。为解决矿用自卸车单气室油气悬架在装载冲击工况下刚度过高导致悬架和车身部件易损坏的问题,设计了一种新型两级压力式油气悬架,利用AMESim仿真平台建立了两级压力式与单气室油气悬架模型,通过实验验证模型的准确性,并对比分析了2种悬架在逐次装载过程中的减振特性。结果表明,相比于单气室悬架,两级压力式油气悬架的油缸压力峰值降低0.19 MPa,活塞压缩行程的最大位移增加0.026 m,加速度功率谱密度峰值降低29.6%,两级压力式油气悬架的振动强度较弱,减振吸能特性较好,为工程车辆油气悬架系统设计提供了参考。

不同喷油嘴的PEMS试验排放特性研究

针对自卸车喷油嘴选型问题,采用便携式车载排放测试系统(PEMS),对两款喷油嘴A、B开展实际道路行驶排放试验,选取恶劣的工况(低载荷、试验持续时间长),对比分析2次PEMS试验的整体试验结果、瞬时排放结果、比排放以及排放因子结果(冷启动、市区、市郊、高速各阶段),最终确认喷油嘴B在实际道路的排放效果优于喷油嘴A。

全钢载重子午线轮胎稳态滚动下的接地印痕仿真分析

以12R22.5全钢载重子午线轮胎为例,采用有限元分析软件建立轮胎的三维有限元模型,仿真分析静态加载、制动和驱动状态下轮胎的接地印痕。结果表明:自由滚动状态下轮胎的接地印痕面积小于静态加载状态下轮胎的接地印痕面积,且自由滚动状态下轮胎的接地印痕压力区域更为集中,接地印痕压力的最大值大于静态加载状态下轮胎的接地印痕压力的最大值;自由滚动状态下,随着行驶速度的增大,轮胎的接地印痕面积逐渐减小,接地印痕压力逐渐增大;制动状态下,轮胎的接地印痕前端的接地面积小于后端的接地面积,而接地印痕前端的压力大于后端的压力;驱动状态下,轮胎的接地印痕前端凸出,后端趋近为水平线,而接地印痕前端的压力小于后端的压力。

基于CNN-LSTM的重型自卸车侧翻预警模型

为解决重型自卸车的侧翻预警问题,基于CNN-LSTM神经网络构造了重型自卸车的侧翻预警模型。利用Trucksim与MATLAB/Simulink搭建了重型自卸车仿真模型,以横向载荷转移率等于±0.85为侧翻阈值,提取了不同工况下的车辆运行参数,利用车辆运行参数,训练CNN-LSTM重型自卸车侧翻预警模型,并分别与基于CNN、LSTM搭建的预警模型对比。结果表明:CNN-LSTM重型自卸车侧翻预警模型预测准确率为98.31%;感受性曲线的曲线下面积为0.999,高于由单一神经网络所搭建的侧翻预警模型。

纯电重卡集群与电网友好互动的聚合调控系统设计与功能分析

在“双碳”战略目标持续推动下,重型卡车“油改电”发展势头强劲,纯电重卡(PEHT)已成为物流运输的主要方式。针对PEHT与电网友好互动的难点,从架构设计和功能应用的视角提出PEHT集群与电网友好互动的聚合调控系统。首先,基于电网侧视角,对上层PEHT集群互动管控平台的综合功能应用场景进行设计;然后,基于聚合商侧视角,构建中层PEHT充换电站聚合管控平台的六大功能;最后,基于负荷侧视角,对下层PEHT充换电站智能边缘终端从数据处理、资源管理、优化控制3个方面构建功能模块。分析表明,该系统实现了PEHT集群与电网的友好互动,有利于提升电网的安全稳定、灵活运行。

汽车起重机卷扬随动系统设计与应用

汽车起重机因机动性好、吊载灵活的优点已成为施工作业中的吊载主力,其主要包含汽车底盘、变幅机构、回转机构、伸缩机构和吊重机构,传统模式下要完成伸臂动作,必须不断地放主钩、放副钩、伸臂、再次放钩,并且稍不留神吊钩容易冲顶毁坏臂头滑轮。完成缩臂动作首先要收主钩、收副钩、缩臂、再次收绳,不然吊钩容易落地引起张力不足导致卷扬钢丝绳乱绳。卷扬随动技术能够很好地解决这些痛点,在伸缩臂过程中卷扬自动跟随旋转,旋转速度跟随臂长变化率,实时保证吊钩悬挂于安全范围内,包含3种模式(1)臂头变化模式——伸缩臂过程中吊钩和臂头的距离实时保持固定;(2)地面随动模式——吊钩和地面的距离实时保持固定;(3)智能随动模式——根据臂长自动调整吊钩高度,伸臂越长放绳越多。