摘要
很多因素如油缸动态特性、结构弹性、作业对象等对挖掘机动力学有着重要影响,为解决挖掘动载荷计算问题,综合考虑结构弹性、油缸特性、作业对象等因素提出挖掘机挖掘动力学系统模型。为取得精度和效率权衡,将动臂、斗杆、连杆等结构简化为梁单元;对形状复杂的铲斗结构,采用子结构自由度凝聚法对形状复杂的铲斗简化建模;采用弹簧阻尼单元模拟铲斗与作业对象关系模型;将油缸等效为两节点单元,该单元包含压力、位移和速度等变量;然后将结构与油缸模型组装成整体的动力学模型,采用Newmark算法完成动力计算;以某50t挖掘机动臂提升冲击工况为案例计算及试验分析,动力计算得到的动载荷与试验测试结果吻合,动载荷峰值误差小于6%,证明方法和模型的正确性。分析结果表明:采用油缸动力学模型比采用位移驱动模型模拟油缸用于动力计算的准确度提升约5倍,而结构弹性对挖掘动载荷的影响较小。
Many factors, such as, dynamic characteristics of hydro-cylinder, structural flexibility, excavating objects and excavator-soil interaction affect digging dynamic behavior of hydraulic excavators during their operation. Here, to solve digging dynamic load calculation problems, an excavator’s digging dynamic model comprehensively considering factors mentioned above was proposed. To achieve a good balance between accuracy and efficiency, all slender structures including movable arms, bucket rods and connecting rods were simplified as beam elements. Complex shape structures like bucket, etc. were simply modeled using the sub-structure DOF condensation method. The bucket-excavating object relation was modeled as a spring-damper element. Hydro-cylinders were modeled as two-node elements containing variables of pressure, displacement and velocity, etc. Then, all structural elements and hydro-cylinder elements were assembled to form a global finite element system model, and perform dynamic computation using Newmark algorithm. Finally, a 50t excavator’s movable arm lifting under impact condition was taken as a case study to do computation and test analysis. The results showed that the computed dynamic loads agree well with measured ones in tests, the error of dynamic load peak values is less than 6%, these verify the correctness of the proposed method and model;compared with using the displacement driven model to simulate hydro-cylinder in dynamic computation, the accuracy of applying the proposed hydro-cylinder model in dynamic computation is increased by 5 times, while structural flexibility has a smaller effect on digging dynamic load.
作者
冯豪
杜群贵
于树栋
FENG Hao;DU Qungui;YU Shudong(School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China;Research Institute, Guangxi Liugong Machinery Co., Ltd., Liuzhou 545007, China;Department of Mechanical and Industrial Engineering, Ryerson University, Toronto M5B2K3, Canada)
出处
《振动与冲击》
EI
CSCD
北大核心
2019年第13期242-248,共7页
Journal of Vibration and Shock
基金
广西科学研究与技术开发项目(桂科攻1598007-46)
关键词
挖掘机
动力学建模
动态载荷
油缸模型
有限元
excavator
dynamic modeling
dynamic loads
hydro-cylinder model
finite element
