本文關(guān)鍵詞：面向不同應力比的復合材料拉—拉疲勞壽命能量預測法研究　出處：《南京航空航天大學》2016年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 復合材料 疲勞壽命 能量方法 能量耗散 熱耗散 非彈性變形能

【摘要】：以試驗方法獲取不同應力比下復合材料的疲勞壽命,所耗費的時間和經(jīng)濟成本太高,因此一直以來,研究人員都關(guān)注于研究能夠降低試驗成本的快速預測復合材料疲勞壽命的理論和實驗方法。能量方法是研究疲勞的重要方法之一,但現(xiàn)有的疲勞能量理論還存在許多難點和不足。為此,本文對復合材料疲勞的能量過程進行研究,并嘗試建立一個能夠預測復合材料壽命的能量方法。復合材料疲勞過程中,輸入的機械功以多種能量形式向外界耗散,其中絕大部分轉(zhuǎn)化為耗散能和非彈性變形能。輸入功可以用循環(huán)滯回能表示,且與疲勞載荷條件和循環(huán)加載次數(shù)有關(guān);熱耗散是能量耗散的主要形式,其變化與溫度的變化相似;非彈性變形能是導致復合材料從裂紋萌生、擴展直至發(fā)生疲勞斷裂破壞的能量,它與材料的損傷狀態(tài)是直接相關(guān)的。為探究復合材料疲勞過程中的能量變化規(guī)律,本文對玻璃纖維復合材料層合板進行了靜拉伸試驗以及疲勞試驗,試驗的同時用高精度的紅外熱像儀記錄了疲勞過程中的溫度變化,并對一些典型的試驗現(xiàn)象和結(jié)果進行了分析和規(guī)律總結(jié)。對復合材料拉-拉疲勞載荷下遲滯回能的變化規(guī)律研究發(fā)現(xiàn),疲勞過程中應變變程和對數(shù)遲的遲滯回能占應變能密度比值都隨循環(huán)次數(shù)線性增加的,進而建立了對循環(huán)滯回能量化描述的模型,并對所建模型進行了驗證,結(jié)果與試驗值吻合較好。從復合材料疲勞過程循環(huán)滯回能、熱耗散和非彈性變形能之間的關(guān)系,結(jié)合材料溫度的變化得到了非彈性變形能的定量描述;而復合材料受單一形式的拉-拉疲勞載荷時,疲勞破壞的非彈性變形能與疲勞壽命之間存在一一對應的關(guān)系,且此關(guān)系是材料自身的力學屬性可通過疲勞試驗獲得。綜合了以上的研究內(nèi)容,結(jié)合所作復合材料疲勞試驗,建立了復合材料疲勞壽命的能量法預測模型。并對所建壽命預測模型進行了驗證,從結(jié)果看模型對疲勞壽命的預測比較準確。
[Abstract]:The fatigue life of the composites under different stress ratios is obtained by the test method, the time and economic cost are too high, so it has been all along. Researchers have focused on the theory and experimental methods of fast prediction of fatigue life of composite materials which can reduce the test cost. Energy method is one of the important methods to study fatigue. However, the existing fatigue energy theory still has many difficulties and shortcomings. Therefore, the energy process of composite fatigue is studied in this paper. An energy method is established to predict the life of composite materials. In the fatigue process of composite materials, the input mechanical work is dissipated to the outside world in a variety of forms. Most of them are transformed into dissipative energy and inelastic deformation energy. The input work can be expressed by cyclic hysteresis energy, which is related to fatigue load condition and cyclic loading times. Heat dissipation is the main form of energy dissipation and its variation is similar to that of temperature. Inelastic deformation energy is the energy that leads to crack initiation, propagation and fatigue fracture failure. It is directly related to the damage state of the material. In order to investigate the energy change law of the composite during fatigue, the static tensile test and fatigue test of glass fiber composite laminates are carried out in this paper. At the same time, the temperature change during fatigue was recorded by high precision infrared thermal imager. Some typical experimental phenomena and results are analyzed and summarized. The ratio of hysteresis energy to strain energy density increases linearly with the number of cycles during fatigue. A model for describing the energy of cyclic hysteresis is established and verified. The results are in good agreement with the experimental data. The quantitative description of inelastic deformation energy is obtained from the relationship among cyclic hysteresis energy, heat dissipation and inelastic deformation energy during fatigue process. When the composite is subjected to a single form of tensile and tensile fatigue load, there is a one-to-one relationship between the inelastic deformation energy of fatigue failure and the fatigue life. This relationship is the mechanical properties of the material itself can be obtained through fatigue tests. Combined with the above research content, combined with the fatigue test of composite materials. The prediction model of fatigue life of composite materials by energy method is established, and the prediction model of fatigue life is verified. The results show that the model is accurate in predicting the fatigue life of composite materials.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TB33

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