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Author: search.filters.author.Bonthu, D.Subject: search.filters.subject.3-D printing

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    Additive Manufacturing of Short Silk Fiber Reinforced PETG Composites
    (Elsevier Ltd, 2022) Kn, V.; Bonthu, D.; Doddamani, M.; Pati, F.
    The growing demand for customized medical devices like prostheses, orthoses, and implants is the prime motive for a surge in the investigation of 3D printable biocomposites. PETG (Polyethylene terephthalate glycol) based composites can be a good choice for biomedical applications. Specific characteristics of this material like biocompatibility, ease of formability, stable thermomechanical properties, and high chemical, and abrasion resistance make it suitable for biomedical applications. However, there are very few studies on the 3D printing of PETG-based composites. Development of a robust 3D printing protocol is required for any novel natural fiber reinforced PETG composites. This study presents natural fiber-reinforced PETG biocomposite filament preparation and 3D printing with the developed composite filaments. Silk was used as a filler material due to its high thermal stability and high tensile strength. Composite filaments with 2 wt%, 5 wt%, and 10 wt% silk were prepared using the extrusion process. Further, we developed a protocol for 3D printing with the developed composites to fabricate various 3D structure. Both filaments and printed specimens were characterized morphologically, structurally, and mechanically. The melt flow rate of the filaments decreased with an increase in fiber content which was a bottleneck for printing 10% silk-PETG composites. Micro-CT results validate an increase in void content in filaments on filler addition. The highest flexural modulus and flexural strength were exhibited by 2% silk-PETG printed parts and a 60% increase in compressive modulus compared to pure PETG. Tensile tests show that 2 wt% fiber addition significantly increased elastic modulus (2466.72 MPa) compared to pure PETG (902.81 MPa), whereas the surface roughness of printed composites increased with filler content. Finally, a lower limb prosthetic socket prototype was printed with a desktop 3D printer to demonstrate its potential for biomedical applications. © 2022 Elsevier Ltd
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    Dynamic response of 3D printed functionally graded sandwich foams
    (Emerald Publishing, 2023) Bonthu, D.; Bharath, B.; Bekinal, S.I.; Jeyaraj, J.; Doddamani, M.
    Purpose: The purpose of this study was to introduce three-dimensional printing (3DP) of functionally graded sandwich foams (FGSFs). This work was continued by predicting the mechanical buckling and free vibration behavior of 3DP FGSFs using experimental and numerical analyses. Design/methodology/approach: Initially, hollow glass microballoon-reinforced high-density polyethylene-based polymer composite foams were developed, and these materials were extruded into their respective filaments. These filaments are used as feedstock materials in fused filament fabrication based 3DP for the development of FGSFs. Scanning electron microscopy analysis was performed on the freeze-dried samples to observe filler sustainability. Furthermore, the density, critical buckling load (Pcr), natural frequency (fn) and damping factor of FGSFs were evaluated. The critical buckling load (Pcr) of the FGSFs was estimated using the double-tangent method and modified Budiansky criteria. Findings: The density of FGSFs decreased with increasing filler percentage. The mechanical buckling load increased with the filler percentage. The natural frequency corresponding to the first mode of the FGSFs exhibited a decreasing trend with an increasing load in the pre-buckling regime and an increase in post-buckled zone, whereas the damping factor exhibited the opposite trend. Originality/value: The current research work is valuable for the area of 3D printing by developing the functionally graded foam based sandwich beams. Furthermore, it intended to present the buckling behavior of 3D printed FGSFs, variation of frequency and damping factor corresponding to first three modes with increase in load. © 2023, Emerald Publishing Limited.