碳纖維紙對玻璃纖維複材於濕熱老化監測性能之影響

Abstract

玻璃纖維強化高分子複合材料（Glass Fiber Reinforced Polymer, GFRP）因具備高強度、耐腐蝕與輕量化等優勢，廣泛應用於工程結構中。然而長期服役於海水等濕熱環境下，其機械性質易隨時間劣化，為提升其健康監測能力，本研究透過結構健康監測（Structural Health Monitoring, SHM），監測試片在機械負載和濕熱環境影響下的劣化程度。本研究以真空輔助樹脂轉注（Vacuum Assisted Resign Transfer, VARTM）製程製作GFRP試片，並探討在材料基材中將奈米碳管混入環氧樹脂，另外製作玻璃纖維布疊層中加入碳纖維紙疊層之GFRP試片，探討兩種試片對電性監測之幫助。 為了解試片在濕熱老化的拉伸與疲勞破壞情況，對試片在濕熱環境中進行不同天數的環境處理，並同時進行導電性監測，探討不同濕熱環境下的機械性質與監測電壓之間的相關性並透過對機械試驗破壞之試片的微觀觀察探討其關聯性，最後比較在機械試驗之監控上、濕熱老化的監控上，在GFRP的疊層中加入碳纖維紙能否更好的監控試片破壞與老化。 實驗結果顯示，加入碳纖維紙的GFRP在濕熱環境中的電壓監測值隨時間增加，且與拉伸強度與疲勞壽命有一定關聯性，相較單純混入奈米碳管的 GFRP，更好的監控了試片之濕熱老化與破壞。 總體來說，本研究發現濕熱環境對玻璃纖維複合材料的弱化，並運用導電性監測、機械試驗性質來探討兩者的相互關係。進而得知加入碳纖維紙在GFRP 結構健康度監控中可作為提升複合材料感測能力之方法。然而，量化破壞的程度才是能真正運用在實體的結構健康監測上，需更了解進濕熱老化、機械性質、與導電性材料的關係，以提高對複合材料結構性能監測的準確度。

Glass Fiber Reinforced Polymer (GFRP) composites are widely used in engineering structures due to their advantages such as high strength, corrosion resistance, and lightweight characteristics. However, when subjected to long-term service in hygrothermal environments such as seawater, their mechanical properties tend to degrade over time. To enhance their health monitoring capabilities, this study applies Structural Health Monitoring (SHM) to evaluate the degradation behavior of GFRP specimens under mechanical loading and hygrothermal conditions. The GFRP specimens were fabricated using the Vacuum Assisted Resin Transfer Molding (VARTM) process. Two types of conductive GFRP composites were prepared: (1) epoxy resin mixed with carbon nanotubes (CNTs), and (2) GFRP laminates with embedded carbon fiber paper layers. This study investigates how these conductive modifications contribute to electrical signal-based monitoring. To understand the tensile and fatigue failure behavior under hygrothermal aging, specimens underwent environmental conditioning for varying durations. During this process, electrical conductivity monitoring was conducted to explore the relationship between mechanical properties and voltage responses under different hygrothermal conditions. Fractured specimens from mechanical testing were further analyzed microscopically to examine the failure mechanisms. The effectiveness of carbon fiber paper in monitoring mechanical damage and environmental degradation in GFRP laminates was then compared. Experimental results show that the voltage signals of GFRP specimens embedded with carbon fiber paper increased with time under hygrothermal aging, and these changes correlated with tensile strength and fatigue life. Compared to GFRP specimens modified only with CNTs, those with carbon fiber paper demonstrated improved monitoring capability for both aging and failure behavior. In summary, this study confirms that hygrothermal environments weaken the performance of GFRP composites. By integrating electrical conductivity monitoring and mechanical testing, the correlation between material degradation and sensing responses was established. The inclusion of carbon fiber paper is shown to be a promising method for enhancing the sensing capability of GFRP in applications. However, quantitative evaluation of damage severity remains essential for practical SHM deployment. Further investigation into the interplay among hygrothermal aging, mechanical behavior, and conductive networks is necessary to improve the accuracy of structural health assessments for composite materials.