摘要
由于某產品發(fā)射裝置筒蓋系統(tǒng)在工作過程中承受復雜多相流瞬時沖擊作用，導致其結構上聯(lián)接螺栓發(fā)生了延遲斷裂失效，給產品的正常工作帶來了一定的安全隱患。因此采用緩沖吸能裝置對其進行降載來解決這個實際工程問題具有較大的實際意義和參考價值。
泡沫鋁材料作為一種吸能效果較為理想的金屬材料得到了廣泛應用，本文以此提出采用附著泡沫鋁吸能層作為緩沖吸能結構的方案來考察其對筒蓋系統(tǒng)的降載效果。首先，以泡沫鋁材料為研究對象建立了單胞泡沫鋁有限元模型，并分析其動態(tài)壓縮力學性能，得出了不同相對密度泡沫鋁在受到沖擊載荷時其應力應變特征曲線, 結果表明與相關理論及試驗較為吻合；其次，建立了筒蓋系統(tǒng)有限元模型以及后續(xù)建立的附著泡沫鋁吸能層的筒蓋系統(tǒng)有限元模型，并通過采用流固耦合情況下外載荷為壓力場時聯(lián)接螺栓所受最大等效應力的校核以及模型的模態(tài)振型的校核兩種方式對所建立的筒蓋系統(tǒng)有限元模型進行校核，校核結果證明所建立的筒蓋系統(tǒng)有限元模型是合理和可行的；最后，通過選取不同范圍的泡沫鋁材料相對密度和厚度作為參變量，對所建立附著泡沫鋁吸能層的筒蓋系統(tǒng)有限元模型進行分析，考察泡沫鋁對筒蓋系統(tǒng)在工作時的緩沖降載效果，最終達到了緩沖降載的目的并獲得了能夠有效降載的泡沫鋁吸能層的相對密度以及厚度的最優(yōu)選取范圍。
分析了另一種廣泛用于緩沖吸能裝置的結構，即薄壁管狀吸能結構。著重分析了圓形截面和正六邊形截面的管狀吸能結構的吸能性能，并得出圓形管狀結構在吸能性能上優(yōu)于正六邊形管狀結構。以圓形截面為研究對象，在吸能性能上對其尺寸參數(shù)進行了優(yōu)化并得到了最終優(yōu)化的尺寸參數(shù)。最后以優(yōu)化后得到的圓形截面管狀結構作為緩沖吸能結構來考察其對筒蓋系統(tǒng)的降載效果，結果表明圓形截面管狀結構作為吸能裝置起到了一定的降載效果。最終，通過與泡沫鋁吸能層的降載效果比較得出，泡沫鋁吸能層對筒蓋系統(tǒng)的降載效果要優(yōu)于圓形截面管狀結構的降載效果。

關鍵詞：筒蓋系統(tǒng)； 降載； 有限元分析； 泡沫鋁吸能層； 管狀吸能結構







Abstract
The cover system of launching unit of a product bear the transient impact action by complex multiphase flow during the course of working, resulting in the failure of delayed fracture of connecting bolts of bearing base on its structure, which will introduce some potential safety hazards into the normal operation of the product. For this reason, it is imperative to use the buffer absorbing device to load shedding，and it is significant and valuable to study and solve this physical problem of engineering.
As a metal material foamed-aluminium is widely used with its good absorbtion effective, this paper points out that the plan of buffering energy-absorbing structure of attached foamed-aluminium absorption layer is adopted to investigate the load shedding effect on the cover system. Firstly, it represents the excellent characteristics shown by the foamed-aluminum absorption layer being energy-absorbing structure, and these characteristics can be subjects investigated to establish a finite element model with unit-cell foamed aluminum for analyzing its relative performance, from which the stress-strain characteristic curve of foam aluminum with differently relative density can be obtained, when impacted by impulse loads and the reliability of analyses certified; and then the geometrical model of cover system is established and the finite element model of cover system applied in this paper is finally determined by the finite element model based on the comparison of two classification methods, and the checking can be carried out via the finite element model based on two methods and the checking results demonstrate that the finite element model of cover system established is reasonable and feasible;The finite element model of cover system in the attached foamed-aluminum absorption layer is established and the relative density and thickness of foamed-aluminum materials with different ranges is selected as parameters, in order to investigate the buffering load shedding effect on cover system at operating, and the aim of buffering load shedding is achieved finally and the selection range of optimal parameters of foamed-aluminum absorption layer.
Another structure widely used in buffering energy-absorbing device is described and analyzed, i.e. thin-walled tube type energy-absorbing structure. The focus for analysis is on the energy absorption capacity of tubular energy absorption structure with circular cross section and regular hexagon cross section and the energy absorption capacity of the structure of circular tube type is superior to that of the structure of regular hexagon tube type. Taking the circular cross section as research object, its size parameters are optimized on the energy absorption capacity and the size parameters which are finally optimized are obtained. At last, the optimized structure of circular cross section tube type is taken as a buffering energy absorption structure to inspect the load shedding effect on the cover system, and the results show that taking this structure as the energy absorption device can play a role in shedding loads. Ultimately, compared with the load shedding effect of foamed-aluminum absorption layer, this effect is better than that of the structure with circular cross section tube type...