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基于LS-DYNA和BP神经网络的修枝机跌落冲击响应研究

发布时间:2018-08-13 08:38
【摘要】:剧烈地冲击碰撞使得很多机电类产品在其使用寿命内呈现失效的状态。跌落冲击所引发的毁伤也是园林修枝机的主要失效形式。当前,电动园林修枝工具产品的设计开发一般遵从“产品原始设计-制造样机-跌落试验-产品优化设计”的传统模式,这会耗费大量的人力物力成本,已越来越不适合小机电,特别是产品个性化、结构复杂的电动园林修枝器具的市场要求。因此,研究经济实用且准确高效的修枝机产品设计开发模式,建立预测修枝机抗冲击性能的新方法和设计合理的缓冲防护复合材料结构成为亟需解决的热点问题。本文以宁波市产业技术创新重大专项(2015B11031)——“高效长寿命低噪音刀片切割系统的研发及产业化应用”和山西省山西省自然科学基金(201601D102035)——“泡沫铝-聚氨酯复合结构缓冲吸能特性及机理研究”为支撑,对某型号园林修枝机的跌落冲击响应开展研究。本文从跌落冲击理论及动力学分析方法,园林修枝机跌落仿真与跌落试验,修枝机结构优化设计,BP神经网络预测模型建立和缓冲防护复合材料结构设计等几个方面进行了深度探究。针对内部结构复杂的园林修枝机在跌落冲击动态过程中存在的不确定性,运用Hypermesh和DYNA-ANSYS/LS联合仿真技术,对修枝机在水平跌落和竖直侧向跌落两种极限工况下的跌落过程进行有限元仿真分析。然后在同样的工况下,对修枝机进行现场跌落试验。对比分析园林修枝机跌落仿真和跌落试验的结果,寻找到园林修枝机受到跌落冲击后影响修枝机使用寿命的易损部件。然后在Hypermesh中对园林修枝机发生跌落冲击后的易损部件进行结构优化设计,并通过有限元仿真验证改进结构是否符合要求。利用跌落仿真和跌落试验相结合的方法可更好地探究修枝机在发生跌落时的冲击应力响应规律,为其结构优化提供科学依据,从而设计了满足使用需求的修枝机结构。利用改进前的符合修枝机跌落实际情况的修枝机跌落仿真参数化模型,得到修枝机在不同工况下跌落后主要部件(齿轮箱和旋转管)的最大冲击应力样本数据共20组,用于神经网络的训练与验证。通过建立跌落高度、跌落角度、地面材质与主要部件最大冲击应力值之间的BP神经网络模型,运用有限元仿真技术和神经网络相结合的方法,预测不同跌落冲击状态下园林修枝机的主要部件跌落冲击最大应力值,为园林修枝机耐撞性测试与可靠度评估提供新的参考,弥补跌落仿真时间过长的缺憾。最后,结合冲击试验和有限元仿真两种方法,设计了性能更优的缓冲防护复合材料结构,可将其广泛地应用于产品的运输包装中,以避免修枝机等产品在运输、堆码等过程所造成的跌落冲击中发生破坏。
[Abstract]:Severe impact makes many mechanical and electrical products appear to be invalid in their service life. The damage caused by drop impact is also the main failure form of garden pruning machine. At present, the design and development of electric garden pruning tools generally follow the traditional mode of "product original design-manufacturing prototype-drop test-product optimization design", which will cost a lot of manpower and material resources. It has become more and more unsuitable for the market requirements of electric garden pruning apparatus, especially the individualized and complex structure of the products. Therefore, the research of economical, practical, accurate and efficient pruning machine product design and development model, the establishment of a new method to predict the impact resistance of the pruning machine and the design of reasonable cushioning and protective composite structure have become the hot issues that need to be solved. In this paper, Ningbo Industrial Technology Innovation Project (2015B11031)-"Research and Development of High efficiency and long Life low noise cutting system and its industrialization Application" and Shanxi Natural Science Foundation (201601D102035)-"Foamed Aluminium-Polyurethane Composite" Study on the Energy absorption characteristics and Mechanism of structure cushioning The drop impact response of a garden pruning machine was studied. The drop impact theory and dynamic analysis method, drop simulation and drop test of garden pruning machine are introduced in this paper. The structure optimization design of pruning machine and the establishment of BP neural network prediction model and the structural design of cushioning and protecting composite materials were studied in depth. In view of the uncertainty existing in the dynamic process of dropping impact of garden pruning machine with complex internal structure, the joint simulation technology of Hypermesh and DYNA-ANSYS/LS is used. The drop process of the pruning machine under the two limiting conditions of horizontal drop and vertical lateral drop was simulated and analyzed by finite element method. Then under the same working condition, the field drop test of the pruning machine is carried out. The results of drop simulation and drop test of garden pruning machine were compared and the vulnerable parts of garden pruning machine which affected the service life of garden pruning machine were found. Then the structural optimization design of the vulnerable parts of the garden pruning machine after falling impact is carried out in Hypermesh, and the finite element simulation is used to verify whether the improved structure meets the requirements. By combining drop simulation and drop test, the response law of impact stress of pruning machine can be better explored, which provides scientific basis for structural optimization, and thus designs the pruning machine structure that meets the needs of application. By using the parameterized model of the pruning machine drop which accords with the actual situation of the pruning machine before the improvement, the maximum impact stress sample data of the main parts (gearbox and rotary tube) of the pruning machine after dropping under different working conditions are obtained in 20 groups. It is used for training and verification of neural network. By establishing the BP neural network model between drop height, drop angle, ground material and the maximum impact stress of main components, the method of combining finite element simulation technology with neural network is used. The maximum stress value of the main parts of the garden pruning machine under different drop impact conditions is predicted, which provides a new reference for the crashworthiness test and reliability evaluation of the garden pruning machine, and makes up for the drawback of the falling simulation time. Finally, combined with impact test and finite element simulation, a better cushioning and protective composite structure is designed, which can be widely used in the transportation packaging of products, so as to avoid the transportation of pruning machines and other products. The damage occurred in the drop impact caused by the stacking process.
【学位授予单位】:中北大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TU986.32

【参考文献】

相关期刊论文 前10条

1 李淑娟;仲晨;张居中;;异型缓冲垫的静态缓冲性能[J];包装工程;2017年03期

2 孙亮;陈希良;齐明思;;基于LS-DYNA的修枝机跌落仿真分析[J];包装工程;2017年03期

3 孙亮;齐明思;王俊元;;泡沫铜-聚氨酯复合结构静力学及传热性能研究[J];热加工工艺;2016年20期

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5 张晓川;任春华;计宏伟;冯智R,

本文编号:2180447


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