【摘要】：碳纖維增韌環(huán)氧樹脂基復合材料具有輕質、高強、可設計性優(yōu)良的特點,因此一直備受各界研究者們的青睞。近年來,漸進損傷分析方法(CDM)被廣泛地應用于航空航天復合材料結構。然而,層合板的漸進損傷和連續(xù)剛度退化通常表現(xiàn)出高度的非線性。如何理解能量耗散后的損傷演化機理至關重要。復合材料層合板在低速沖擊載荷下的失效破壞機理尤為復雜,通常伴隨著應變局部化現(xiàn)象的產(chǎn)生。本文旨在針對復合材料層合板的面內(nèi)損傷,引入由Ba?ant等人發(fā)展起來的非局部積分理論,通過在漸進失效模型中嵌入VUMAT子程序來解決低速沖擊載荷下復合材料的局部化問題。仿真結果表明,非局部漸進失效模型能夠很好地模擬復合材料試樣在不同載荷條件下的失效演化和動力學響應,有效地改善了復合材料分析模型的網(wǎng)格敏感性問題。為進一步驗證非局部漸進失效沖擊模型的有效性,通過試驗與有限元仿真相結合的方法,圍繞民機復合材料結構沖擊后剩余壓縮、剩余剪切強度問題展開了研究。首先,針對T700/QY8911和T700/3234復合材料層合板的在低速沖擊下的損傷演化及沖擊響應進行非局部有限元模擬,將改進的Hashin準則、雙線性及指數(shù)型損傷演化規(guī)律引入子程序中,驗證了非局部算法在解決沖擊損傷模擬問題中的準確性。然后,通過ABAQUS重啟動分析,將沖擊損傷以預定義場(形式賦予復合材料無損結構,分別完成了低速沖擊-壓縮/剪切模擬的全過程,仿真結果與試驗吻合良好,大大提高了剩余強度模型的分析精度。最后,研究了引入沖擊損傷后的復合材料梁腹板結構在剪切載荷下的失效機理和承載特性,發(fā)現(xiàn)在子層屈曲和纖維斷裂的共同作用下,試驗件最終失去承載能力,發(fā)生沿45?方向的失效破壞。結合非局部漸進失效模擬,完成了對復合材料梁腹板結構損傷容限的初步評估。
[Abstract]:Carbon fiber toughened epoxy matrix composites have been favored by researchers for their advantages of light weight, high strength and good designability. In recent years, the progressive damage analysis method (CDM) has been widely used in aerospace composite structures. However, progressive damage and continuous stiffness degradation of laminated plates usually show high nonlinearity. How to understand the mechanism of damage evolution after energy dissipation is very important. The failure mechanism of composite laminated plates under low speed impact loads is particularly complicated and usually accompanied by strain localization. Aiming at the in-plane damage of composite laminates, the nonlocal integral theory developed by Ba?ant et al is introduced to solve the localization problem of composites under low speed impact by embedding VUMAT subroutine in the progressive failure model. The simulation results show that the nonlocal progressive failure model can well simulate the failure evolution and dynamic response of composite specimens under different loading conditions and effectively improve the mesh sensitivity of composite analysis model. In order to further verify the effectiveness of the non-local progressive failure impact model, the residual compression and residual shear strength of civil aircraft composite structures after impact were studied by means of the combination of test and finite element simulation. Firstly, the damage evolution and impact response of T700/QY8911 and T700 / 3234 composite laminates under low speed impact are simulated by non-local finite element method. The improved Hashin criterion, bilinear and exponential damage evolution rules are introduced into the subroutine. The accuracy of the nonlocal algorithm in solving the impact damage simulation problem is verified. Then, through the ABAQUS restarting analysis, the impact damage is predefined in the form of the composite structure, and the whole process of the low-speed impact-compression / shear simulation is completed, respectively. The simulation results are in good agreement with the test results. The precision of residual strength model is greatly improved. Finally, the failure mechanism and load-bearing characteristics of composite beam web structure with impact damage under shear load are studied. It is found that under the joint action of sub-layer buckling and fiber fracture, the ultimate bearing capacity of the specimen is lost and the bearing capacity is 45? Directional failure. Combined with nonlocal progressive failure simulation, the damage tolerance of composite beam web structure was evaluated.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33

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