航空钛合金损伤构件CFRP单面贴补修复界面I型断裂力学特性

方金荣; 胡俊山; 陈培林; 范春浩; 张霖; 田威

航空钛合金损伤构件CFRP单面贴补修复界面I型断裂力学特性

南京航空航天大学　机电学院, 南京 210016

基金项目: 江苏省自然科学基金面上项目(BK20231444)；直升机传动系统能力提升预研专项(TC230Y04S-37)；中央高校基本科研业务费专项资金资助(NT2024013)

详细信息

通讯作者:
胡俊山，博士，副教授，硕士生导师，研究方向为飞行器智能装配/修复技术与装备　E-mail: hujunshan@nuaa.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2024-05-20
- 修回日期: 2024-06-18
- 录用日期: 2024-07-08
- 网络出版日期: 2024-07-26

Mechanical characterization of mode I fracture at the interface of CFRP single-sided patch repair of damaged aerospace titanium alloy components

College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China

Funds: National Natural Science Foundation of Jiangsu Province (BK20231444); Helicopter Drivetrain Capability Enhancement Pre-Research Project (TC230Y04S-37); Special Funds for Basic Research Operating Costs of Central Universities (NT2024013)

摘要

摘要: 针对航空钛合金损伤贴补修复结构在I型受载条件下的力学响应与断裂特性，本文采用共固化成型方法设计了碳纤维增强树脂基预浸料(Carbon Fiber Reinforced Polymer, CFRP)单面贴补钛合金构件的修复试样，通过双悬臂梁试验，系统的研究了补片厚度、铺层方向以及表面处理方法三个典型因素对修复界面I型断裂力学特性的影响规律，以峰值载荷和层间断裂韧性为指标评估整体修复效果。结合试样在宏观和微观尺度下的失效模式与断面形貌分析，揭示了钛合金/CFRP贴补修复试样I型静态分层扩展的破坏机制。研究结果表明，随着补片厚度的增加，试样弯曲刚度和纤维桥联规模呈上升趋势，修复界面的I型断裂性能明显提高，失效模式均表现为胶膜粘附失效与内聚破坏到CFRP界面破坏的演化过程；在复合铺层试样中，补片底部的0°铺层表现出最强的分层路径约束作用，而45°铺层能够诱发裂纹的层间迁移以提高增韧效果，二维编织型补片则具有最佳的修复效果；胶膜内聚破坏为表面处理试样的主要失效模式，其中硫酸阳极化的增韧效果最为显著，断裂韧性较石英喷砂和400#砂纸打磨分别提高3.8%和1.9%，相比无处理试样则提高了19.2%。该结论为I型受载条件下钛合金损伤复合材料贴补修复工艺的优化设计与应用实践提供参考。
- 复合材料 /
- 贴补修复 /
- I型断裂 /
- 断裂韧性 /
- 航空金属 /
- 双悬臂梁
Abstract: To investigate the mechanical response and fracture characteristics of adhesively bonded titanium alloy structures under mode I loading conditions, this study employed a co-curing method to fabricate repair specimens with single-sided carbon fiber reinforced polymer (CFRP) patches bonded to titanium alloy substrates. The effects of patch thickness, ply orientation, and surface treatment on mode I interfacial fracture mechanics were systematically examined using double cantilever beam (DCB) tests. Peak load and interlaminar fracture toughness were utilized as quantitative metrics to evaluate the overall repair performance. Furthermore, failure modes and fracture surface morphologies at both macroscopic and microscopic scales were analyzed to elucidate the underlying failure mechanisms of mode I static delamination in the titanium alloy/CFRP repaired specimens. The results reveal that increasing the thickness of the patch leads to a rising trend in both the bending stiffness of the specimen and the extent of fiber bridging. The mode I fracture performance of the repair interface improves significantly, with failure modes consistently evolving from adhesive failure of the glue film and cohesive damage to failure at the CRFP interface. For multidirectional laminates, the 0° ply at the bottom of the patch exhibits the strongest constraint on delamination paths, while the 45° ply effectively induces inter-ply crack migration, enhancing the toughening effect. Notably, the two-dimensional woven patch demonstrates the best repair performance. For surface-treated specimens, cohesive failure of the adhesive film is the predominant failure mode. Specifically, sulfuric acid anodization provides the most significant toughening effect, increasing fracture toughness by 3.8% and 1.9% compared to quartz sandblasting and 400# sandpaper abrasion, respectively, and by 19.2% compared to untreated specimens. These conclusions provide references for the optimized design and practical application of damage repair processes under mode I loading conditions for titanium alloy components.
- composite materials /
- patch repair /
- mode I fracture /
- fracture toughness /
- aviation metal /
- double cantilever beam

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图 1 钛合金/CFRP预浸料单面贴补修复试样示意图

Figure 1. Schematic illustration of titanium alloy-CFRP single-sided patch repaired specimen

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图 2 钛合金/CFRP试样贴补修复过程: (a)补片切割；(b)超声清洗；(c)高温干燥；(d)材料准备；(e)铺贴/辊压；(f)修复试样

Figure 2. Repair process of titanium-CFRP specimen: (a)Prepreg cutting；(b)Ti-alloy cleaning；(c)Drying；(d)Processed materials；(e)Lay up；(f)Repaired specimen

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图 3 修复试样固化过程及温度曲线：(a)待固化试样及加压方式；(b)高精度自动热压机；(c)固化温度曲线

Figure 3. Curing process and temperature curves of repaired specimen: (a) Specimen to be cured and method of pressurization; (b) high-precision automatic machine; (c) curing temperature curve

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图 4 DCB试验装置：(a) 整体实验平台；(b) 试样与夹持装置；(c) 纤维桥联现象

Figure 4. Test setups for DCB specimens: (a) Experimental platform;(b) Specimen and clamping device; (c) Bridging fibers

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图 5 不同厚度补片修复试样的载荷-位移曲线

Figure 5. Load–displacement curves of repaired specimens with different patch thicknesses

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图 6 不同厚度补片修复试样的断裂韧性曲线(R曲线)

Figure 6. Fracture toughness curves (R-curves) of repaired specimens with different patch thicknesses

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图 7 不同厚度补片修复试样的I型断裂性能与弯曲刚度

Figure 7. Mode I fracture properties and bending stiffness of repaired specimens with different patch thicknesses

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图 8 修复试样剥离界面失效模式分类：(a) 胶膜粘附失效；(b) 胶膜内聚破坏；(c) CFRP界面破坏

Figure 8. Failure mode classification of repair specimen peel interface:(a) Adhesive failure; (b) Cohesive failure; (c) CFRP interface failure

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图 9 不同厚度补片修复试样的分层断面：(a) 1.14 mm；(b) 1.52 mm；(c) 1.90 mm；(d) 2.28 mm；(e) 2.66 mm；(f) 失效模式百分比示意图

Figure 9. Delamination sections of repaired specimens with different patch thicknesses: (a) 1.14 mm;(b) 1.52 mm; (c) 1.90 mm; (d) 2.28 mm; (e) 2.66 mm;(f) Failure mode percentage schematic

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图 10 不同铺层方向修复试样的载荷-位移曲线

Figure 10. Load–displacement curves of repaired specimens with different layup directions

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图 11 (a)不同铺层方向修复试样的断裂韧性曲线(R曲线);(b)不同铺层方向修复试样的I型断裂性能与弯曲刚度

Figure 11. (a) Fracture toughness curves (R-curves) of repaired specimens with different layup directions; (b) Comparison of mode I fracture properties and bending stiffness of repaired specimens with different layup directions

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图 12 不同铺层方向修复试样的分层断面：(a) [±45]_{2 s} ; (b) [0/90]_{2 s} ; (c) [90/0]_{2 s} ; (d) [0/±45/90]_s ; (e) [±45/0₂]_s ; (f) [(0/90)_w]₈

Figure 12. Delamination sections of repaired specimens with different layup directions:(a) [±45]_{2 s} ; (b) [0/90]_{2 s} ; (c) [90/0]_{2 s} ; (d) [0/±45/90]_s ; (e) [±45/0₂]_s ; (f) [(0/90)_w]₈

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图 13 不同铺层方向修复试样分层断面的微观形貌：(a) [±45]_{2 s}；(b) [0/90]_{2 s}；(c) [90/0]_{2 s}；(d) [0/±45/90]_s；(e) [±45/0₂]_s；(f) [(0/90)_w]₈

Figure 13. Microscopic morphology of delamination sections of repaired specimens with different layup orientations: (a) [±45]_{2 s}; (b) [0/90]_{2 s}; (c) [90/0]_{2 s};(d) [0/±45/90]_s; (e) [±45/0₂]_s; (f) [(0/90)_w]₈

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图 14 不同表面处理工艺修复试样的载荷-位移曲线

Figure 14. Load–displacement curves of repaired specimens with different surface treatments

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图 15 (a)不同表面处理修复试样的断裂韧性曲线(R曲线)；(b)不同表面处理修复试样的I型断裂性能与弯曲刚度

Figure 15. (a) Fracture toughness curves (R-curves) of repaired specimens with different surface treatments; (b) Comparison of mdoe I fracture properties and bending stiffness of repaired specimens with different surface treatments

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图 16 不同表面处理工艺修复试样的分层断面：(a) 400#砂纸打磨；(b) 硫酸阳极化；(c) 石英喷砂；(d) 无处理

Figure 16. Delamination sections of repaired specimens with various surface treatments: (a) Sandpapering-400#; (b) Sulphuric acid anodizing; (c) Quartz-blasting; (d) Untreated

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图 17 经处理后的钛合金表面微观形貌：(a)无处理；(b)400#砂纸打磨；(c)硫酸阳极化；(d)石英喷砂；及修复试样粘接界面：(e)无处理；(f)400#砂纸打磨；(g)硫酸阳极化；(h)石英喷砂

Figure 17. Microstructure of the Ti-alloy substrate surfaces treated by: (a) Untreated; (b) Sandpapering-400#; (c) Sulphuric acid anodizing; (d) Quartz-blasting; and bonding interfaces in repaired specimens: (e) Untreated; (f) Sandpapering-400#; (g) Sulphuric acid anodizing; (h) Quartz-blasting

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表 1 钛合金/CFRP单面贴补修复试样几何参数

Table 1. Geometric parameters of titanium alloy-CFRP single-sided patch repaired specimen

Parameter	Description	Value / mm
l₀	Hinge additional length	17
a₀	Length of initial crack	50
L	Total length	150
b	Specimen width	25
t	Ti-alloy thickness	1.5
t₀	Thickness of adhesive film	0.12

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表 2 结构胶膜、单向及平纹编织CFRP力学性能参数

Table 2. Mechanical properties of adhesive film unidirectional (UD) and plain weave (PW) CFRP

Adhesive SY-24 C		UD Laminate (T700/725)		PW Laminate (T700/725)
Property	Value	Property	Value	Property	Value
E/MPa	5750	E₁/GPa	119	E₁/GPa	66.28
G/MPa	1920	E₂/GPa	9	E₂/GPa	61.8
σ/MPa	451.6	E₃/GPa	9	E₃/GPa	10
τ/MPa	36.5	ν_12, ν₁₃	0.309	ν₁₂	0.057
GC n /(N·mm⁻¹)	0.48	ν₂₃	0.35	ν_13, ν₂₃	0.25
GC s /(N·mm⁻¹)	0.64	G₁₂, G₁₃ /GPa	4	G₁₂/GPa	4.52
GC t /(N·mm⁻¹)	0.64	G₂₃/GPa	3.33	G₁₃, G₂₃ /GPa	4
Notes: E, G – Elastic modulus in tension and shear; σ, τ – Failure strengths in tension and shear; GC n– Toughness in tension; GC s, GC t– Toughness in shear; E_ii (i =1, 2, 3) – Young’s modulus (i direction); G_ij (i, j =1, 2, 3) – Shear modulus (i-j plane); v_ij (i, j=1, 2, 3) – Poisson’s ratio (i-j plane).

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表 3 钛合金/CFRP单面贴补修复试样影响因素及参数设置

Table 3. Influencing factors and parameter setting of titanium alloy-CFRP single-sided patch repaired specimen

Repair factors	Symbol	Factor settings
Patch thickness/mm	T_P	1.14, 1.52, 1.90, 2.28, 2.66
Lay-up direction/(°)	θ_P	[0]₈, [±45]_{2 s}, [0/90]_{2 s}, [90/0]_{2 s}, [(0/90)_w]₈, [0/±45/90]_s, [±45/0₂]_s
Surface treatment	R_T	Sandpapering, Quartz-blasting, Sulphuric acid anodizing, Untreated

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