In-plane and flexural performance of cellulose-fibre reinforced composite as the skin in wood-core sandwich panels
Takala, Saara-Kaisa (2023)
Takala, Saara-Kaisa
2023
Materiaalitekniikan DI-ohjelma - Master's Programme in Materials Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2023-01-10
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202212058890
https://urn.fi/URN:NBN:fi:tuni-202212058890
Tiivistelmä
There has been a growing interest in bio-based raw materials in use for composite manufacturing. Biocomposites are a combination of bio-based raw materials. The usage of natural fibers as a reinforcement for composite structures is a challenging application. The challenges of natural fibers rise from the weaker mechanical properties than traditionally used fibers. Although, natural fibers tend to have for example good damping properties compared to traditional fibers such as glass or carbon.
The main objective of this thesis was to evaluate a new cellulose-based fiber reinforced composite. The focus was on comparison between the new reinforcement fiber and traditional glass fiber in composites. The wanted application where the new fiber reinforcement was willing to be used was downhill skis. On the sports equipment perspective, especially the damping properties were inspected.
The two materials were cellulose-based fiber reinforced composite and glass fiber reinforced composite, and the used matrix was bio-epoxy. Two different sample structures were used: laminate and sandwich structure. The samples were tested in composite laminate form with a tensile test, dynamic mechanical analysis, and a vibration test. For composite sandwich structure a fatigue analysis was performed. The samples were manufactured by using a hand lay-up technique and cured with a heated pneumatic process. The lay-up of manufactured samples was mimicking the final application of a downhill ski.
The tensile properties of the samples differed from each other. The glass fiber reinforced composite was stronger and had higher modulus than the cellulose-based fiber reinforced composite. The glass fiber composite had also higher strain percentage at maximum load compared to the cellulose-based composite. The dynamic mechanical analysis showed that the cellulose-based composite dissipates energy more than the glass fiber composite and has increased damping properties than glass fiber composite. The vibration test supported the test results from the dynamic mechanical analysis. The cellulose-based composite damped vibrations more compared to the glass fiber composite. Finally, the performed fatigue test showed different failure mechanism between the samples. The glass fiber composite samples suffered mostly delamination and face wrinkling in fatigue testing. In the cellulose-based composite samples delamination and permanent deformation was observed in the fatigue test.
The main objective of this thesis was to evaluate a new cellulose-based fiber reinforced composite. The focus was on comparison between the new reinforcement fiber and traditional glass fiber in composites. The wanted application where the new fiber reinforcement was willing to be used was downhill skis. On the sports equipment perspective, especially the damping properties were inspected.
The two materials were cellulose-based fiber reinforced composite and glass fiber reinforced composite, and the used matrix was bio-epoxy. Two different sample structures were used: laminate and sandwich structure. The samples were tested in composite laminate form with a tensile test, dynamic mechanical analysis, and a vibration test. For composite sandwich structure a fatigue analysis was performed. The samples were manufactured by using a hand lay-up technique and cured with a heated pneumatic process. The lay-up of manufactured samples was mimicking the final application of a downhill ski.
The tensile properties of the samples differed from each other. The glass fiber reinforced composite was stronger and had higher modulus than the cellulose-based fiber reinforced composite. The glass fiber composite had also higher strain percentage at maximum load compared to the cellulose-based composite. The dynamic mechanical analysis showed that the cellulose-based composite dissipates energy more than the glass fiber composite and has increased damping properties than glass fiber composite. The vibration test supported the test results from the dynamic mechanical analysis. The cellulose-based composite damped vibrations more compared to the glass fiber composite. Finally, the performed fatigue test showed different failure mechanism between the samples. The glass fiber composite samples suffered mostly delamination and face wrinkling in fatigue testing. In the cellulose-based composite samples delamination and permanent deformation was observed in the fatigue test.