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激光辐照碳纤维增强环氧树脂基复合材料层合板热力破坏行为
Alternative TitleThermal-mechanical damage behavior of carbon fiber reinforced epoxy composite laminate by laser irradiation
刘彦池
Thesis Advisor魏炳忱 ; 吴臣武
2019-05-31
Degree Grantor中国科学院大学
Place of Conferral北京
Subtype博士
Degree Discipline一般力学与力学基础
Keyword复合材料层合板,激光辐照,温度场,热应力场,层间开裂
Abstract

碳纤维增强树脂基复合材料因其具优异的力学性能及其面向使用环境的设计适应性,正逐渐被广泛应用于航空航天等领域。这种复合材料层合板激光加工过程中的热力影响区性能评估,以及以这种复合材料层合板为主体结构的无人机的激光热力破坏设计,都需要准确掌握层合板在相对较低能量密度的激光辐照温度场、热应力以及损伤机制。复合材料层合板的正交各向异性、铺层多样性以及激光辐照热载荷的时域非稳态和空间不均匀性,致使层合板热力损伤模式可能会非常复杂;然而,由于复合材料层合板的层间区域仅仅包含树脂基底、构成了相对薄弱的区域,因此在激光辐照作用下的热力损伤很可能倾向于集中在这些局部区域、形成以层间开裂为主导的失效模式。

为了揭示复合材料层合板激光辐照下的热力损伤行为、特别是层间断裂机制,本文将同时采用理论分析、数值模拟和实验观测方法,逐步递进研究复合材料层合板激光辐照温度场、热应力场及其损伤失效行为,侧重于揭示层合板激光辐照层间开裂行为及其参数依赖规律。研究工作大致从以下三部分来阐述:

第一部分:为了研究连续激光辐照复合材料层合板的热响应,研究了激光辐照复合材料层合板瞬态温度场及其演化规律。利用拉普拉斯变换和傅里叶余弦变换,推导连续激光辐照下复合材料层合板瞬态热传导问题的解析解。并且开展相同条件下的激光辐照复合材料层合板三维瞬态热传导有限元分析,将温度场数值计算结果与解析解结果进行比较、相互校验。同时利用解析解和数值解分析、研究激光辐照复合材料层合板温度对典型参数变化的依赖规律。

第二部分:为了研究连续激光辐照复合材料层合板的热应力场,基于剪切变形理论和变分原理推导连续激光辐照复合材料层合板的应力应变场解析解。将激光辐照复合材料层合板的温度场解析解作为输入热载荷,求解给定温度场下的复合材料层合板热应力变分解。然后针对复合材料层合板连续激光辐照下的热弹性响应和层间开裂行为,建立包含材料开裂的三维热弹性有限元模型;利用层间界面节点耦合/解耦的方式,初步模拟复合材料层合板在连续激光辐照下的层间开裂过程。

第三部分:为了从实验上揭示复合材料层合板激光辐照烧蚀和热力损伤机制,采用典型模式激光、开展碳纤维增强树脂基复合材料层合板激光辐照试验研究。利用光学显微镜和扫描电镜观察层合板烧蚀形貌或损伤开裂特征,并进而从实验上研究了碳纤维增强树脂基复合材料层合板脉冲激光烧蚀行为及其激光参数依赖规律。

Other Abstract

Carbon fiber reinforced plastic has been widely used in aerospace and other fields due to their excellent mechanical properties and design adaptability to the service environment. Because of the performance evaluation of the thermal irradiation zone in the laser processing of this composite laminate and the laser thermal damage design of the unmanned aerial vehicle with the composite laminate as its main structure, it is necessary to accurately understand the laser irradiation temperature field, thermal stress and damage mechanism of the composite laminate in the relatively low energy density.

The thermal damage pattern of composite laminate may be very complicated due to the anisotropy of composite laminate, the diversity of laminates and the time-domain instability and spatial heterogeneity of laser irradiation thermal load. However, since the interlaminar region of composite laminate only contains the resin substrate and constitutes a relatively weak region, the thermal damage under the action of laser irradiation is likely to be concentrated in these local regions, forming a failure mode dominated by interlaminar cracking.

In order to reveal the composite laminate under the irradiation of laser thermal damage behavior, especially the interlaminar fracture mechanism, this paper will study the temperature field, thermal stress field and damage failure behavior of composite laminates under laser irradiation step by step, using the method of theoretical analysis, numerical simulation and experimental observation, focusing on revealing the interlayer cracking behavior of composite laminates under laser irradiation and the law of parameter dependence. The research work is mainly elaborated from the following three parts:

Part I: in order to study the thermal response of composite laminate irradiated by continuous laser, the transient temperature field and its evolution process of composite laminate irradiated by laser are studied. Using Laplace transform and Fourier cosine transform, the analytic solution of the transient heat conduction problem of composite laminate under continuous laser irradiation is derived. In addition, the 3-d transient heat conduction finite element analysis of laser irradiated composite laminate under the same conditions was carried out. At the same time, the dependence of the temperature on the typical parameters of the composite laminates irradiated by laser is studied by using analytical and numerical solutions.

Part ii: in order to study the thermal stress field of composite laminate subjected to continuous laser irradiation, the analytical solution of stress and strain field of composite laminate subjected to continuous laser irradiation was derived based on the shear deformation theory and variational principle. Taking the analytical solution of the temperature field of laser irradiated composite laminate as the input thermal load, the thermal stress decomposition of composite laminate under a given temperature field is solved. Then a three-dimensional thermoelastic finite element model including material cracking was established for the thermoelastic response and interlaminar cracking behavior of composite laminate under continuous laser irradiation. The interlayer cracking process of composite laminate under continuous laser irradiation is preliminarily simulated by coupling/decoupling method of interlayer interface nodes.

Part iii: in order to reveal the thermal damage mechanism of composite laminate by laser irradiation, the experimental study on laser irradiation of carbon fiber reinforced resin matrix composite laminate was carried out. The characteristics of interlaminar cracking were observed by means of optical microscope and scanning electron microscope, and then the pulsed laser ablation behavior and the law of laser parameter dependence of carbon fiber reinforced resin matrix composite laminate were studied experimentally.

Language中文
Document Type学位论文
Identifierhttp://dspace.imech.ac.cn/handle/311007/79123
Collection国家微重力实验室
Recommended Citation
GB/T 7714
刘彦池. 激光辐照碳纤维增强环氧树脂基复合材料层合板热力破坏行为[D]. 北京. 中国科学院大学,2019.
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