温度环境下复合材料层合结构疲劳寿命预测方法研究

发布时间：2018-01-17 19:00

本文关键词：温度环境下复合材料层合结构疲劳寿命预测方法研究　出处：《南京航空航天大学》2015年硕士论文　论文类型：学位论文

【摘要】：复合材料层合结构作为航空航天结构的关键材料近年来广泛使用于各种航空航天结构中,并收到了良好的减重、抗疲劳、曲面外形优异等效果。随着复合材料的深入应用,对其在温度环境下的疲劳行为的研究显得必要而紧迫。首先,本文提出并建立了基于最弱环理论的层合结构静强度/疲劳寿命预测方法。从单层板强度与疲劳寿命服从Weibull分布出发,基于概率理论及最弱环理论,以层合板的每一单层作为研究对象,认为层合板是由各单层串联的环,一旦某一层发生了失效,整个层合结构便发生失效。基于该学术观点,推导建立了层合板失效概率与单层板失效概率之间的关系,即层合板失效概率与单层板特征寿命、疲劳循环以及分散系数之间的关系,结合单层板的等寿命曲线,建立了复合材料层合板的强度/疲劳寿命预测方法。引用文献中的T300/BMP316层合板在室温下的静强度/疲劳寿命试验数据,采用该方法对层合板的拉伸强度与疲劳寿命进行预测,静强度预测误差在8%以内,疲劳寿命预测误差在三倍误差带之内。其次,将最弱环理论与有限元方法相结合,提出并建立了基于最弱环理论的层合结构静强度/疲劳寿命有限元预测方法。认为单元内任意一点发生失效,则整个单元便发生失效;当失效单元扩展到整个结构无法承载时,则整个结构便发生失效。基于此,推导了单元失效概率与单层板失效概率之间的关系即单元失效概率与单层板特征寿命、疲劳循环以及分散系数之间的关系,建立了相应的有限元预测方法。引用文献中的层合板接头的疲劳试验数据,采用该方法对层合板接头的疲劳寿命预测误差在三倍误差带之内。然后,本文采用Mivehchi的温度与单层板刚度/强度公式,得到温度环境下单层板的强度/刚度与温度的关系式,并用于修正室温下的单层板等寿命曲线,即特征疲劳寿命与温度环境下应力的关系式,从而解决了温度环境下的复合材料层合板结构的强度与寿命设计分析难题。同时,为了验证本文提出的预测方法在温度环境下的有效性,本文进行了温度环境下的层合板静强度和疲劳寿命预测计算与试验验证。开展了基于T300/BMP316层合板温度环境下静强度/疲劳试验研究,得到了T300/BMP316层合板的静强度/疲劳寿命数据。采用本文提出的方法编制了ANSYS APDL程序对其静强度/疲劳寿命进行预测并与试验结果比较,静强度预测值误差都在±10%以内,100?C下的疲劳寿命预测值在1倍误差带之内,200?C下的疲劳寿命预测值在2倍误差带之内。且单元失效形式与断件吻合,证明了该方法的有效性。
[Abstract]:Composite laminated structure, as the key material of aerospace structure, has been widely used in various aerospace structures in recent years, and has received good weight loss and fatigue resistance. With the further application of composite materials, it is necessary and urgent to study its fatigue behavior in temperature environment. First of all. A prediction method for static strength / fatigue life of laminated structures based on the weakest ring theory is proposed and established in this paper. Based on the Weibull distribution of the strength and fatigue life of single layer plates. Based on the probability theory and the weakest ring theory, every single layer of laminated plate is considered as the ring in series by each layer. Based on this academic viewpoint, the relationship between the failure probability of laminated plate and the failure probability of single-layer plate is derived, that is, the failure probability of laminated plate and the characteristic life of single-layer plate. The relationship between fatigue cycle and dispersion coefficient is combined with the equal-life curve of single-layer plate. A method for predicting the strength / fatigue life of composite laminates was established, and the static strength / fatigue life test data of T300 / BMP316 laminates at room temperature were cited. The method is used to predict the tensile strength and fatigue life of laminated plates. The prediction error of static strength is less than 8%, and the prediction error of fatigue life is within three times error band. By combining the weakest ring theory with the finite element method, a finite element method for predicting the static strength / fatigue life of laminated structures based on the weakest ring theory is proposed and established. Then the whole unit becomes invalid; When the failure element is extended to the entire structure, the whole structure will fail. Based on this. The relationship between the failure probability of the element and the failure probability of the single-layer plate is deduced, that is, the relationship between the failure probability of the element and the characteristic life, fatigue cycle and dispersion coefficient of the single-layer plate. The corresponding finite element prediction method is established, and the fatigue life prediction error of laminated joints is within three times of the error band by using the fatigue test data of laminated joints in the literature. In this paper, the formula of the relationship between the strength / stiffness and the temperature of the single-layer plate is obtained by using the formula of Mivehchi's temperature and the stiffness / strength of the monolayer plate, and the equation is used to modify the isobarth curve of the single-layer plate at room temperature. The relationship between the characteristic fatigue life and the stress in temperature environment can solve the problem of strength and life design of composite laminated plate structure under temperature environment. At the same time. In order to verify the effectiveness of the proposed prediction method in the temperature environment. In this paper, the static strength and fatigue life of laminated plates under temperature environment are calculated and verified. The static strength / fatigue test of laminated plates based on T300 / BMP316 is carried out. The static strength / fatigue life data of T300 / BMP316 laminates are obtained. The ANSYS is compiled by the method proposed in this paper. The static strength / fatigue life of the program was predicted by APDL and compared with the test results. The error of static strength prediction is within 卤10%? The prediction value of fatigue life under C is 200? The prediction value of fatigue life under C is within the error band of 2 times, and the failure form of the element is in agreement with that of the broken part, which proves the validity of the method.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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