基于LS-DYNA和BP神經網絡的修枝機跌落沖擊響應研究
發(fā)布時間：2018-08-13 08:38
【摘要】：劇烈地沖擊碰撞使得很多機電類產品在其使用壽命內呈現(xiàn)失效的狀態(tài)。跌落沖擊所引發(fā)的毀傷也是園林修枝機的主要失效形式。當前,電動園林修枝工具產品的設計開發(fā)一般遵從“產品原始設計-制造樣機-跌落試驗-產品優(yōu)化設計”的傳統(tǒng)模式,這會耗費大量的人力物力成本,已越來越不適合小機電,特別是產品個性化、結構復雜的電動園林修枝器具的市場要求。因此,研究經濟實用且準確高效的修枝機產品設計開發(fā)模式,建立預測修枝機抗沖擊性能的新方法和設計合理的緩沖防護復合材料結構成為亟需解決的熱點問題。本文以寧波市產業(yè)技術創(chuàng)新重大專項(2015B11031)——“高效長壽命低噪音刀片切割系統(tǒng)的研發(fā)及產業(yè)化應用”和山西省山西省自然科學基金(201601D102035)——“泡沫鋁-聚氨酯復合結構緩沖吸能特性及機理研究”為支撐,對某型號園林修枝機的跌落沖擊響應開展研究。本文從跌落沖擊理論及動力學分析方法,園林修枝機跌落仿真與跌落試驗,修枝機結構優(yōu)化設計,BP神經網絡預測模型建立和緩沖防護復合材料結構設計等幾個方面進行了深度探究。針對內部結構復雜的園林修枝機在跌落沖擊動態(tài)過程中存在的不確定性,運用Hypermesh和DYNA-ANSYS/LS聯(lián)合仿真技術,對修枝機在水平跌落和豎直側向跌落兩種極限工況下的跌落過程進行有限元仿真分析。然后在同樣的工況下,對修枝機進行現(xiàn)場跌落試驗。對比分析園林修枝機跌落仿真和跌落試驗的結果,尋找到園林修枝機受到跌落沖擊后影響修枝機使用壽命的易損部件。然后在Hypermesh中對園林修枝機發(fā)生跌落沖擊后的易損部件進行結構優(yōu)化設計,并通過有限元仿真驗證改進結構是否符合要求。利用跌落仿真和跌落試驗相結合的方法可更好地探究修枝機在發(fā)生跌落時的沖擊應力響應規(guī)律,為其結構優(yōu)化提供科學依據(jù),從而設計了滿足使用需求的修枝機結構。利用改進前的符合修枝機跌落實際情況的修枝機跌落仿真參數(shù)化模型,得到修枝機在不同工況下跌落后主要部件(齒輪箱和旋轉管)的最大沖擊應力樣本數(shù)據(jù)共20組,用于神經網絡的訓練與驗證。通過建立跌落高度、跌落角度、地面材質與主要部件最大沖擊應力值之間的BP神經網絡模型,運用有限元仿真技術和神經網絡相結合的方法,預測不同跌落沖擊狀態(tài)下園林修枝機的主要部件跌落沖擊最大應力值,為園林修枝機耐撞性測試與可靠度評估提供新的參考,彌補跌落仿真時間過長的缺憾。最后,結合沖擊試驗和有限元仿真兩種方法,設計了性能更優(yōu)的緩沖防護復合材料結構,可將其廣泛地應用于產品的運輸包裝中,以避免修枝機等產品在運輸、堆碼等過程所造成的跌落沖擊中發(fā)生破壞。
[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.
【學位授予單位】：中北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU986.32
[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.
【學位授予單位】：中北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU986.32
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本文編號：2180447
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