Abstract: The unreasonable design of crane structure under traditional experience modes leads to mismatch between the bearing capacity and actual service scenarios.For this reason,a closed-loop optimization design method for crane structures based on digital twins was proposed by introducing the digital design mode.The integrated concept of ‘operating status-bearing performance-shape characteristics' was utilized,and a digital twin system for crane structure closed-loop optimization design was constructed from three levels,namely virtual and real operations and performance mapping,data fusion and interaction,service and visualization presentation.For the stress prediction,based on the structural stress point cloud samples under different working conditions,the K-Nearest Neighbor algorithm (KNN),Ball-Tree algorithm and RBF neural network were used to construct a coarse and fine grid node matching model and stress prediction model.The rapid prediction of structural stress under random loads was achieved.Subsequently,for the structural optimization,stress prediction results were employed to construct the constraints on static strength and fatigue strength.Combined with the main control size parameters of the structure and a multi-objective function composed of quality and life matching,an improved NSGA-Ⅱ algorithm based on NDX operator was adopted to complete the closed-loop optimization design of the crane structure.Taking the YDC20/30 lightweight mobile crane as an example,the feasibility and effectiveness of the proposed method and system were verified.

Key words: digital twin, crane structure, closed-loop optimization design, stress prediction

摘要： 针对传统经验模式下起重机结构设计不合理导致承载性能与实际服役场景不匹配的问题,以数字化设计模式为理念,提出基于数字孪生的起重机结构闭环优化设计方法。首先,利用“运行状态-承载性能-形状特点”一体化的思想,从虚实行性映射、数据融合与交互、服务及可视化呈现3个层面,搭建用于起重机结构闭环优化设计的数字孪生系统。其次,在应力预测方面,以不同工况下的结构应力点云样本为基础,采用K最近邻算法(KNN)、球树算法(Ball-Tree)算法和径向神经网络(RBF),构建粗细网格节点匹配模型和应力预测模型,实现随机载荷作用下结构应力快速预测。而后,在结构优化方面,利用应力预测结果,构建静强度和疲劳强度约束条件,结合结构主控尺寸参数,以及由质量和寿命匹配组成的多目标函数,采用非定向算子(NDX)改进NSGA-Ⅱ算法,完成起重机结构闭环优化设计。最后,以YDC20/30轻小型移动式起重机为例,验证了所提方法及系统的可行性和有效性。

关键词: 数字孪生, 起重机结构, 闭环优化设计, 应力预测