航空学报 > 2025, Vol. 46 Issue (22): 431729-431729   doi: 10.7527/S1000-6893.2024.31729

复合材料海水湿热老化机理与拉伸损伤特征

李天震1, 魏景超2, 曹勇1(), 刘靖宇1, 李永存1, 王文智3   

  1. 1.太原理工大学 应用力学研究所,太原 030024
    2.中国飞机强度研究所 强度与结构完整性全国重点实验室,西安 710065
    3.西北工业大学 航空学院,西安 710072
  • 收稿日期:2024-12-30 修回日期:2025-03-05 接受日期:2025-03-21 出版日期:2025-04-11 发布日期:2025-04-10
  • 通讯作者: 曹勇 E-mail:caoyong@tyut.edu.cn
  • 基金资助:
    国家自然科学基金(12472389);山西省自然科学基金(20210302124325);山西省自然科学基金(202203021212259);山西省科技创新人才团队(领军)专项资助(202204051002006)

Mechanism of seawater hydrothermal aging and tensile damage characteristics of composite materials

Tianzhen LI1, Jingchao WEI2, Yong CAO1(), Jingyu LIU1, Yongcun LI1, Wenzhi WANG3   

  1. 1.Institute of Applied Mechanics,Taiyuan University of Technology,Taiyuan 030024,China
    2.National Key Laboratory of Strength and Structural Integrity,Aircraft Strength Research Institute of China,Xi’an 710065,China
    3.School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China
  • Received:2024-12-30 Revised:2025-03-05 Accepted:2025-03-21 Online:2025-04-11 Published:2025-04-10
  • Contact: Yong CAO E-mail:caoyong@tyut.edu.cn
  • Supported by:
    National Natural Science Foundation of China(12472389);Natural Science Foundation of Shanxi Province(20210302124325);Special Fund for Science and Technology Innovation Teams of Shanxi Province(202204051002006)

摘要:

海水中的湿热和盐雾环境会影响复合材料的性能和服役年限。在空气、纯水、海水和10倍浓度海水环境中对碳纤维增强复合材料(CFRP)开展湿热老化试验,基于Fick扩散定律修正循环变温下海水老化的吸湿模型,饱和吸湿后开展准静态拉伸试验测试力学性能。提出保留湿热应力状态的分步耦合仿真计算策略,用于预测吸湿后的复合材料拉伸损伤特征。该策略分步耦合获得湿热应力场,并将湿热应力导入到拉伸仿真分析模型之中,研究在力学计算模型中考虑湿热膨胀对材料性能劣化的影响。通过试验和仿真研究复合材料在多类环境因素下的吸湿特征和吸湿后的拉伸损伤特征。结果表明:修正吸湿模型和分步耦合仿真策略可有效表征循环温度下多浓度环境下的吸湿过程以及湿热膨胀对材料力学性能的影响;饱和吸湿率随浓度增加而降低,吸湿速率与温度呈明显的正比关系,吸湿速率与浓度成反比;老化后CFRP的弹性模量随浓度增加而微弱降低,强度极限略微降低,树脂基体性能退化为主要老化影响因素;试件失效模式受老化影响可分为片状断裂、爆炸性纤维条状碎裂和纤维-树脂抽离破坏,原因是海水浓度越高对树脂基体的老化作用越明显,导致纤维-树脂结合力降低。

关键词: CFRP, 海水老化, Fick扩散定律, 吸湿特性, 力学性能退化, 失效模式

Abstract:

The hot and humid, salt-laden of seawater can affect the properties and service life of composite materials. Hygrothermal aging tests were conducted on Carbon Fiber Rein-forced Polymer (CFRP) in air, pure water, seawater, and seawater with a tenfold concentration. The moisture absorption model for seawater aging under cyclic temperature variation was modified based on Fick’s diffusion law. Additionally, quasistatic tensile tests were performed to assess the mechanical properties after the composites absorbed moisture to saturation. A stepwise coupled simulation strategy that accounts for hygrothermal stress is proposed to predict the tensile damage behavior of composites after moisture absorption. In this strategy, the hygrothermal stress field is obtained incrementally, and the resulting stress is incorporated into the tensile simulation model. This approach allows the effects of hygrothermal expansion on material cracking to be included in the mechanical calculations. Based on experimental results and simulations, the moisture absorption characteristics and tensile damage behavior of composites under various environmental conditions after moisture absorption were investigated. The main findings are as follows: the modified moisture absorption model and the stepwise coupled simulation strategy effectively characterize the hygroscopic process in multi-concentration environments at cyclic temperatures and the effects of hygrothermal expansion on material mechanical properties. Saturated moisture absorption decreases with increasing concentration, and the rate of moisture absorption is directly proportional to temperature but inversely proportional to concentration. The modulus of elasticity of aged CFRP decreases weakly with increasing concentration, and the strength limit decreases slightly. The degradation of the resin matrix properties is the primary aging influence. The failure modes of specimens affected by aging can be categorized as sheet fracture, explosive fiber-strip fragmentation, and fiber-resin pullout damage. These modes are due to the more pronounced aging effects of higher seawater concentration on the resin matrix, resulting in weakened fiber-resin bonding.

Key words: CFRP, seawater aging, Fick’s diffusion law, moisture absorption, mechanical degradation, failure mode

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