INFLUENCE OF HYDROTHERMAL ENVIRONMENT ON MECHANICAL PROPERTIES AND DAMAGE MECHANISMS OF SANDWICH CFRTP COMPOSITES
Topic(s) : Life cycle performance
Co-authors :
Zhang FAN (JAPAN), Yi WAN (JAPAN), Jun TAKAHASHI (JAPAN)Abstract :
1Introduction
The European Union ("EU") aims to increase its use of renewable energy to at least 32% of the EU's total energy consumption by 2030. To achieve these objectives, further improvements in the lightweighting of wind turbines are necessary. The use of recycled carbon fiber (rCF) in the core of sandwich-structured carbon fiber-reinforced thermoplastic (CFRTP) offers significant advantages, including low density, excellent recyclability, and outstanding mechanical properties, making it potential for offshore wind turbine applications[1]. Currently, some experiments have demonstrated the potential of certain structures, such as using FRP as the skin, flax (natural fiber), and aluminum (metal material) as the core, has noted the potential of sandwich structural[2-3]. However, researchs about the long-term aging impact performance changes of pure carbon fiber sandwich materials, with recycled carbon fiber materials carbon fiber paper-reinforced thermoplastic (CPT) as the core and Sheet Molding Compound (SMC) or unidirectional (UD) are used as the skin, appears to be relatively limited at present.
Besides, when CFRTP materials are used in the components of wind turbine, they must undergo aging in marine environments under operational conditions during this period. These materials are also subjected to potential impact forces, while enduring a hydrothermal environment. Thus, conducting a hydrothermal aging test to evaluate CFRTP is indispensable for the industry application.
2Materials
This study conducted experiments on sandwich structure CFRTP materials manufactured using the spring-backed (SB) phenomenon[4] and rCF. The specimens were fabricated under the condition of 5 MPa and 270 oC by 6 pieces of UD or 2 pieces of SMC, prepregs as skin and 12 pieces of CPT as the core, as shown in the Fig. 1. Additionally, considering the impact of interfacial bonding performance between the skin and core of the sandwich structure on overall material performance, additional resin layers were introduced between the two structures to enhance interfacial bonding and resin infiltration, thereby improving interfacial bonding performance. Then specimens were reheated in 270 oC for 10 min to achieve a certain thickness to achieve the SB ratios of 1, 1.5, and 2. And grouping of specimens are shown in Table 1.
3Experiments
The impact tests were proceeded by a high-speed puncture impact tester (Shimadzu Corporation HITS-P10) for sandwich structures during aging test under the JIS K7084 (Table. 2) after a series of hydrothermal aging tests over five months[5].
Using micro vickers hardness tester (Shimadzu Corporation HMV-G21S) to measure the hardness of the skin following the JIS Z 2244.
4Results
This test tracked the specific impact strength and specific energy absorption which provide insights into the material's dynamic impact performance and energy absorption capability, offering possible insights into improving the design and application of CFRTP materials.
The European Union ("EU") aims to increase its use of renewable energy to at least 32% of the EU's total energy consumption by 2030. To achieve these objectives, further improvements in the lightweighting of wind turbines are necessary. The use of recycled carbon fiber (rCF) in the core of sandwich-structured carbon fiber-reinforced thermoplastic (CFRTP) offers significant advantages, including low density, excellent recyclability, and outstanding mechanical properties, making it potential for offshore wind turbine applications[1]. Currently, some experiments have demonstrated the potential of certain structures, such as using FRP as the skin, flax (natural fiber), and aluminum (metal material) as the core, has noted the potential of sandwich structural[2-3]. However, researchs about the long-term aging impact performance changes of pure carbon fiber sandwich materials, with recycled carbon fiber materials carbon fiber paper-reinforced thermoplastic (CPT) as the core and Sheet Molding Compound (SMC) or unidirectional (UD) are used as the skin, appears to be relatively limited at present.
Besides, when CFRTP materials are used in the components of wind turbine, they must undergo aging in marine environments under operational conditions during this period. These materials are also subjected to potential impact forces, while enduring a hydrothermal environment. Thus, conducting a hydrothermal aging test to evaluate CFRTP is indispensable for the industry application.
2Materials
This study conducted experiments on sandwich structure CFRTP materials manufactured using the spring-backed (SB) phenomenon[4] and rCF. The specimens were fabricated under the condition of 5 MPa and 270 oC by 6 pieces of UD or 2 pieces of SMC, prepregs as skin and 12 pieces of CPT as the core, as shown in the Fig. 1. Additionally, considering the impact of interfacial bonding performance between the skin and core of the sandwich structure on overall material performance, additional resin layers were introduced between the two structures to enhance interfacial bonding and resin infiltration, thereby improving interfacial bonding performance. Then specimens were reheated in 270 oC for 10 min to achieve a certain thickness to achieve the SB ratios of 1, 1.5, and 2. And grouping of specimens are shown in Table 1.
3Experiments
The impact tests were proceeded by a high-speed puncture impact tester (Shimadzu Corporation HITS-P10) for sandwich structures during aging test under the JIS K7084 (Table. 2) after a series of hydrothermal aging tests over five months[5].
Using micro vickers hardness tester (Shimadzu Corporation HMV-G21S) to measure the hardness of the skin following the JIS Z 2244.
4Results
This test tracked the specific impact strength and specific energy absorption which provide insights into the material's dynamic impact performance and energy absorption capability, offering possible insights into improving the design and application of CFRTP materials.