Electronic Theses and Dissertation

Ankle Foot Orthoses (AFO) merupakan alat ortotik yang berfungsi membantu
stabilitas pergelangan kaki dan meningkatkan pola berjalan pada pasien dengan
gangguan gerak. Material konvensional seperti Polypropylene (PP) dan
Polyethylene (PE) memiliki keterbatasan kekuatan dan kekakuan, sehingga
material komposit berbasis karbon prepreg dipertimbangkan sebagai alternatif
yang lebih ringan dan kuat. Penelitian ini bertujuan mengetahui sifat mekanik
material karbon prepreg, menganalisis respons struktural AFO menggunakan
metode Finite Element Analysis (FEA), serta membuat purwarupa sebagai validasi
awal desain. Pengujian tarik dilakukan sesuai ASTM D3039 dan menghasilkan
nilai rata-rata Ultimate Tensile Strength (UTS) sebesar 587,17 MPa, modulus
elastisitas 16,76 GPa, dan densitas 1,336 g/cm³. Hasil FEA menunjukkan bahwa
variasi ketebalan sangat memengaruhi performa struktural AFO. Pada ketebalan
1,2 mm diperoleh tegangan maksimum 94,5 MPa dan deformasi 7,5073 mm;
ketebalan 2 mm menghasilkan tegangan 40,89 MPa dan deformasi 2,0841 mm;
sedangkan ketebalan 3 mm menunjukkan tegangan minimum 16,25 MPa dan
deformasi 0,6999 mm. Purwarupa AFO berhasil dibuat menggunakan empat lapis
karbon prepreg dengan ketebalan rata-rata 1,2 mm, meskipun masih ditemukan
variasi ketebalan dan cacat permukaan pada area tumpang tindih serat.
Berdasarkan hasil simulasi dan pembuatan purwarupa, ketebalan 1,2 mm dapat
digunakan sebagai prototipe, namun ketebalan 2 mm lebih direkomendasikan
untuk penggunaan operasional karena memberikan keseimbangan optimal antara
kekuatan, kekakuan, dan massa.

Ankle Foot Orthoses (AFOs) are orthotic devices designed to assist ankle stability and improve gait patterns in patients with movement disorders. Conventional materials such as polypropylene (PP) and polyethylene (PE) exhibit limitations in strength and stiffness; therefore, carbon prepreg–based composite materials are considered as lighter and stronger alternatives. This study aims to determine the mechanical properties of carbon prepreg material, analyze the structural response of an AFO using Finite Element Analysis (FEA), and fabricate a prototype as an initial design validation. Tensile testing was conducted in accordance with ASTM D3039, resulting in an average Ultimate Tensile Strength (UTS) of 587.17 MPa, an elastic modulus of 16.76 GPa, and a density of 1.336 g/cm³. The FEA results indicate that thickness variation significantly influences the structural performance of the AFO. At a thickness of 1.2 mm, the maximum stress and deformation were 94.5 MPa and 7.5073 mm, respectively; at 2 mm thickness, the stress decreased to 40.89 MPa with a deformation of 2.0841 mm; whereas at 3 mm thickness, the minimum stress of 16.25 MPa and deformation of 0.6999 mm were obtained. The AFO prototype was successfully fabricated using four layers of carbon prepreg with an average thickness of 1.2 mm; however, thickness variations and surface defects were observed in overlapping fiber regions. Based on the simulation and prototyping results, a thickness of 1.2 mm is suitable for prototyping purposes, while a thickness of 2 mm is more recommended for operational use due to its optimal balance between strength, stiffness, and mass.