| 复合体制激光对C/SiC复合材料的多尺度耦合破坏机理研究 | |
| Alternative Title | Multi-scale coupling damage mechanism of C/SiC composites exposed to combined laser |
马特
| |
| Thesis Advisor | 宋宏伟 |
| 2023-05 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Subtype | 博士 |
| Degree Discipline | 工程力学 |
| Keyword | 复合体制激光 激光烧蚀机理 等离子体压力 C/SiC-Ti3SiC2复合材料 多尺度分析模型 |
| Abstract | C/SiC 复合材料是一种重要的高超声速飞行器热防护材料，对其开展强激光 辐照条件下破坏机理研究，有望为高速目标防御提供新的解决思路。然而，这类 低密度耐高温陶瓷基复合材料具有很高的激光破坏阈值，如何在有限的能量输出 条件下实现更为高效的破坏效果，成为高能激光器研发方向所需面对的关键问题。
本文结合不同体制激光的各自优势，开展了复合体制激光对 C/SiC 复合材料的多尺度耦合破坏机理研究，旨在提出具有高效破坏能力的复合体制激光组合模式。不同体制的激光与物质相互作用时会产生不同的效应：连续激光的热力效应、长脉冲激光（μs 级脉宽）的烧蚀效应以及短脉冲激光（ns 级脉宽）的冲击效应。
同时，C/SiC 复合材料具有多种增强相结构以及改性后的多组分基体相，导致复合体制激光与 C/SiC 复合材料相互作用是一个包含复杂物理/化学反应、等离子体状态演化等多种物理过程在内的时间/空间多尺度问题。本文采用实验测量、理论分析以及数值模拟相结合的研究路线对上述问题进行研究。主要的研究工作包括以下几个方面：
1. 建立了一套复合体制激光联合加载及多物理场测量的激光破坏效应实验平台，并开展了关键性能的实验验证。通过将光纤连续激光器与脉冲激光器相结合，实现了复合体制激光联合加载；提出了一种适用于高能激光诱导高温环境正表面破坏过程的宏-细观原位观测技术，在实验条件更复杂的激光与超声速风洞联合实验中验证了该技术的可靠性；通过图像处理方法分析了不同金属材料熔融尾迹区域形成过程与形貌差异；基于粒子图像速度法，并以不同铺层方向时纤维的运动方向为判据，获得了复合材料的瞬时烧蚀深度；探索了复合体制激光对典型金属与复合材料的破坏效应，分析了连续激光与短、长脉冲激光所组成的不同时序方案、激光参数等对破坏效应的影响。
2. 开展了 C/SiC 复合材料在连续激光与脉冲激光不同激光参数下的烧蚀机理研究。首先，研究了连续激光辐照条件下不同激光功率密度对烧蚀行为的影响并分析了烧蚀机理。基于原位观测系统获得了细观尺度的瞬时激光烧蚀行为，通过扫描电子显微镜（SEM）和 X 射线能量色散光谱（EDS）获得了微观形貌和
烧蚀成分，对比分析了不同编织结构以及 MAX 相 Ti3SiC2 陶瓷改性 C/SiC 复合材料的烧蚀行为，确定了各类 C/SiC 复合材料的激光烧蚀机理，探讨了“温度阶跃”现象的发生机理；其次，基于 C/SiC 复合材料的激光烧蚀机理，提出了两种作用机理不同的复合体制激光组合方式：一是利用连续激光与短脉冲激光联合作用的热-冲击耦合效应降低 C/SiC 复合材料的抗氧化性能，基于原位观测系统获得的动态烧蚀过程，发现了连续激光热效应可提高短脉冲激光作用于 C/SiC 复合材料时产生的冲击效应；二是利用连续激光与长脉冲激光耦合作用的热-热叠加效应加快复合材料的烧蚀速率，并通过实验验证了复合体制激光的高效破坏效果。
3. 建立了用于预测 C/SiC 复合材料高温热物性参数与热力学性能参数的多尺度分析模型。针对 2D C/SiC-Ti3SiC2复合材料，提出了考虑孔隙在内的基体微观尺度、包含纤维相/界面相/基体相在内的纤维纱线微观尺度、以及由纤维纱线/ 改性相/基体相所组成的平纹编织细观尺度三个层次下的代表性体积单元模型，预测了2D C/SiC-Ti3SiC2复合材料的热传导性能以及热力学性能，基于实验结果验证了所提出的多尺度分析模型的可靠性，分析了孔隙率、纤维含量和改性相含量对热传导性能以及宏观温度场的影响；对于 3DN C/SiC-Ti3SiC2复合材料，建立了完全均匀化建模方法，提高连续激光与长脉冲激光热-热叠加烧蚀的计算效率，以及适用于连续激光与短脉冲激光热-冲击耦合损伤失效计算的层合结构建模方法，验证了两种建模方法在温度响应方面的一致性和可靠性。
4. 针对连续激光与长脉冲激光复合加载诱导的热-热叠加烧蚀效应，建立了以细观尺度几何特征为传递数据的多尺度烧蚀分析模型。分析了不同连续激光功率密度条件下改性相 Ti3SiC2对 2D C/SiC 复合材料的烧蚀性能影响，以及纤维编织结构对 C/SiC-Ti3SiC2 复合材料烧蚀行为的影响；给出了各个烧蚀机理，包括氧化、热分解和升华反应对总烧蚀的贡献，以及 2D C/SiC 细观编织结构的最大及最小烧蚀深度；在宏观尺度模型中以包络线以及重构后的结果形式描述了细观尺度下因烧蚀速率差异导致的表面粗糙度现象；开展了连续激光与长脉冲激光联合作用时的烧蚀行为研究，分析了激光参数对烧蚀深度的影响，明确了长脉冲激光在复合体制激光烧蚀行为中的增强机理。
5. 针对连续激光与短脉冲激光复合加载诱导的热-冲击耦合破坏效应，建立了包含等离子体压力波模型以及损伤模型在内的数值分析方法。连续激光热效应诱导生成的透明、液态 SiO2类似约束层的作用，能够大幅增加短脉冲激光诱导生成的等离子体压力峰值，因此基于Fabbro 经典理论建立了C/SiC-Ti3SiC2复合材料在连续激光热效应影响下的等离子体压力波模型，明确了模型中的能量转化系数与等离子体初始长度，分析了短脉冲激光的脉宽时间与功率密度对等离子体压力特征的影响；进一步建立了连续激光与短脉冲激光的热-冲击耦合数值计算模型，基于3D Hashin 失效准则分析了损伤状态并开展了不同短脉冲激光参数与连续激光参数对C/SiC-Ti3SiC2 复合材料损伤行为的影响，明确了短脉冲激光对
该作用区域的损伤失效程度的增强效果。
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| Other Abstract | Carbon fiber-reinforced silicon carbide ceramic matrix (C/SiC) composites have gained significant attention as thermal protection materials for hypersonic aircraft due to their excellent mechanical and thermal properties. However, the high laser damage threshold of C/SiC composites poses a challenge in achieving efficient damage effects under limited output laser energy, which is crucial in developing high-power lasers for defense applications. Investigating the damage mechanism of C/SiC composites under high-power laser irradiation can provide insights into developing more effective laser-based defense strategies for high-speed targets. The interaction between lasers and matter is a complex phenomenon that can result in various effects. For instance, the continuous wave laser can induce a thermal effect, whereas the long pulsed laser with pulse widths in the microsecond range can produce an ablation effect, and the short pulsed laser with pulse widths in the nanosecond range can cause an shock effect. C/SiC composites comprise various reinforced and modified multi-component matrix phases, making the laser-matter interaction a multi-scale problem involving intricate physical-chemical reactions and plasma evolution. This study employs a comprehensive research approach integrating experimental measurements, theoretical analysis, and numerical simulations to address these challenges. This approach allows us to comprehensively investigate the diverse effects of laser-matter interaction on C/SiC composites. The research focuses on several key aspects:
1. The experimental platform is established for laser-irradiated damage effects, which incorporates a co-loading combined laser and multi-physical field measurement. The co-loading combined laser is realized through the combination of the continuous wave laser and the pulsed laser. An in-situ observation technology is proposed and verified in the experiment. The formation and shape differences of melt wake regions
in various metal materials are analyzed using an image processing method. The instantaneous ablation depth of composites is obtained by considering the direction of fiber movement in different lay-up directions based on the particle image velocity method. The study investigates the damage effects of combined laser on the typical
metal and composite material. The influence of different timing schemes and laser parameters on the damaging effect is analyzed.
2. The ablation mechanism of C/SiC composites under different laser parameters is studied. Firstly, the study investigates the effect of different laser power densities on the ablation behavior of C/SiC composites exposed to continuous wave laser irradiation. The in-situ observation technology obtains the instantaneous laser ablation behavior at the mesoscale. Microscopic morphology and ablation composition are analyzed using electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The ablation behavior of different braided structures and the MAX phaseTi3SiC2 modified C/SiC composite is compared and analyzed to determine the laser ablation mechanism. The mechanism of the "Temperature Jump" phenomenon is also discussed. Secondly, two combined laser modes are proposed based on the laser ablation mechanism. The first method combines the thermal-shock coupling effect of continuous wave laser and short pulsed laser to reduce oxidation resistance. The thermal superposition effect accelerates the ablation rate, and experiments verify the enhanced destruction effect of the combined laser.
3. A multi-scale model has been developed to predict the thermophysical and thermomechanical parameters of the C/SiC-Ti3SiC2 composite. The model considers the matrix microscale, which includes pores. The fiber yarn microscale includes the fiber, interface, and matrix phases. Moreover, the fiber yarn/modified phase/matrix phase representative volume unit model is established at the plain weave mesoscale. This model predicts the thermal conductivity and thermal diffusion properties of the 2D C/SiC-Ti3SiC2 composite material and has been verified based on experimental results, demonstrating its reliability. Additionally, the effects of porosity, fiber, and modified phase content on thermal conductivity and the macroscopic temperature
field have been analyzed. For the 3DN C/SiC-Ti3SiC2 composite, a fully homogenized modeling method is established to improve the computational efficiency of ablation. A laminated structures modeling method is established for thermal-shock coupling damage failure calculation. The consistency and reliability of the two modeling
methods regarding temperature response are verified, laying the foundation for subsequent ablation and shock calculations.
4. A multi-scale ablation model with mesoscale geometric features as transfer data is established to study the thermal-thermal superposition ablation effect induced by the combined loading of continuous wave laser and long pulsed laser. The influence of the Ti3SiC2 phase on the ablation of the 2D C/SiC composite is analyzed. Furthermore, the effect of fiber structure on the ablation behavior of the C/SiC-Ti3SiC2 composite is studied. Individual ablation mechanisms are identified, including the contribution of oxidation, thermal decomposition, and sublimation reactions to the total ablation. The maximum and minimum ablation depths of mesoscopic braided structures are also determined. The results are displayed as an envelope function in the macro-scale model, which exhibited the surface roughness phenomenon caused by the difference in ablation rate at the mesoscale. The effect of laser parameters on ablation depth is also studied, clarifying the enhanced contribution of long-pulse lasers in the combined laser ablation.
5. A numerical simulation including plasma pressure model and damage model is established to study the thermal-shock coupling damage effect induced by the combined loading of continuous wave laser and short pulsed laser. The generation of transparent and liquid SiO2 under the thermal effect of continuous wave laser has significantly increased the plasma peak pressure induced by a short pulsed laser. In this study, we developed a numerical calculation model based on the Fabbro model to
investigate the shock coupling effect in the C/SiC-Ti3SiC2 composite under continuous and short pulsed laser interaction. The model aims to clarify the energy conversion coefficient and the initial length of the plasma and to analyze the influence of pulse width time and power density of the short pulsed laser on the plasma pressure characteristics. The effect of different laser parameters is examined on the damage
behavior of the C/SiC-Ti3SiC2 composite. Furthermore, we have investigated the enhancing damage effect of short pulsed laser.
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| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://dspace.imech.ac.cn/handle/311007/95694 |
| Collection | 流固耦合系统力学重点实验室 |
| Recommended Citation GB/T 7714 | 马特. 复合体制激光对C/SiC复合材料的多尺度耦合破坏机理研究[D]. 北京. 中国科学院大学,2023. |
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| 84900.pdf（40047KB） | 学位论文 | 开放获取 | CC BY-NC-SA | Application Full Text | ||
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