An automated shrinkage compensation method for the holes fabricated via FFF process

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2019

Tezin Dili: İngilizce

Öğrenci: SARDAR VAYGHANNEZHAD

Danışman: Ulaş Yaman

Özet:

This thesis presents an automated shrinkage compensation algorithm for 2.5D specimens to be fabricated via Fused Filament Fabrication process. The algorithm operates on a closed curve representing the hole of a 2.5D specimen, and generates a corresponding compensation structure regardless of the hole’s geometric characteristics. Accordingly, this thesis initiates with introducing a viscoelastic model that would reproduce the behavior of the PLA filament from the time of extrusion onto the build plate until it is cooled down to room temperature. Based on the viscoelastic model and corresponding mathematical equations, a final strain associated with a 2.5D structure having a central hole is calculated. Finally, to empirically verify the theory behind this work, three types of tests are designed and conducted. Two of these tests are seek to check the validity of the strain rate already obtained, on specimens without bridge lines. The third test setting, however, brings into play the positive effect that bridge lines have on the shrinkage of the central opening.