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Investigation of the carbon fiber-thermoplastic matrix interfacial adhesion
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Insinööritieteiden korkeakoulu |
Master's thesis
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en
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72 + 9
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Abstract
Composite materials such as CFRPs are of great interest in modern technologies since their high mechanical properties make them ubiquitous in aerospace, automotive and sports industries. Using additive manufacturing methods such as material extrusion to print composite is also common, and many mechanical parts in which carbon fiber has been embedded into the 3D-printed thermoplastic matrix are being utilized in various sectors. However, there are limitations in using additive manufacturing to manufacture CFRPs, such as weak interlaminar shear strength between carbon fiber and matrix materials. Therefore, this property needs to be investigated to enhance the mechanical properties of CFRPs in the future.
In this study, the interfacial adhesion between the carbon fiber and thermoplastic matrix is investigated. The theories behind the material extrusion, the carbon fiber and thermoplastics as reinforcement and matrix materials, and their interfacial adhesion and the wetting process of carbon fiber are reviewed. The samples used for the study are printed via material extrusion by Ultimaker and Anisoprint printers. The interfacial adhesive force is calculated and studied using the tensile testing method by measuring the peak force needed to slip the carbon fiber out of the matrix. SEM imaging is also utilized to observe the effects of wetting on the carbon fiber in the samples.
From the experiment, the carbon fiber starts slipping out of the thermoplastic matrix when the embedded length is below 5 mm. There is a linear relationship between the embedded length and the peak load, in which the higher embedded length of the fiber leads to needing higher peak load to slip out the matrix due to higher interfacial adhesion. This phenomenon is caused by the greater contact surface area between the fiber and the matrix at the higher embedded length.
Overall, this thesis develops a methodology to investigate the interfacial adhesion between the carbon fiber and thermoplastic matrix and presents how the embedded length of fiber affects the interfacial adhesive force. It also provides the groundwork for future avenues of research, such as the effects of printing parameters and additive manufacturing processes on interfacial adhesion.
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Supervisor
Partanen, JouniThesis advisor
Kukko, KirsiKumar, Sunil Siddharth