The biomaterials polylactic acid (PLA), polycaprolactone (PCL), and hydroxyapatite (HA) were selected to fabricate composite filaments for 3D printing fused filament fabrication (FFF), which was used to fabricate a composite biomaterial for an interlocking nail for canine diaphyseal fractures instead of metal bioinert materials. Bioactive materials were used to increase biological activities and provide a high possibility for bone regeneration to eliminate the limitations of interlocking nails. HA was added to PLA and PCL granules in three ratios according to the percentage of HA: 0%, 5%, and 15% (PLA/PCL, PLA/PCL/5HA, and PLA/PCL/15HA, respectively), before the filaments were extruded. The test specimens were 3D-printed from the extruded composite filaments using an FFF printer. Then, a group of test specimens was coated by silk fibroin (SF) using the lyophilization technique to increase their biological properties. Mechanical, biological, and chemical characterizations were performed to investigate the properties of the composite biomaterials. The glass transition and melting temperatures of the copolymer were not influenced by the presence of HA in the PLA/PCL filaments. Meanwhile, the presence of HA in the PLA/PCL/15HA group resulted in the highest compressive strength (82.72 ± 1.76 MPa) and the lowest tensile strength (52.05 ± 2.44 MPa). HA provided higher bone cell proliferation, and higher values were observed in the SF coating group. Therefore, FFF 3D-printed filaments using composite materials with bioactive materials have a high potential for use in fabricating an interlocking nail for canine diaphyseal fractures.

The full-thickness articular cartilage defect (FTAC) is an abnormally severe grade of articular cartilage (AC) injury. An osteochondral autograft transfer (OAT) is the recommended treatment, but the increasing morbidity rate from osteochondral plug harvesting is a limitation. Thus, the 3D-printed bilayer’s bioactive-biomaterials scaffold is of major interest. Polylactic acid (PLA) and polycaprolactone (PCL) were blended with hydroxyapatite (HA) for the 3D-printed bone layer of the bilayer’s bioactive-biomaterials scaffold (B-BBBS). Meanwhile, the blended PLA/PCL filament was 3D printed and combined with a chitosan (CS)/silk firoin (SF) using a lyophilization technique to fabricate the AC layer of the bilayer’s bioactive-biomaterials scaffold (AC-BBBS). Material characterization and mechanical and biological tests were performed. The fabrication process consists of combining the 3D-printed structure (AC-BBBS and B-BBBS) and a lyophilized porous AC-BBBS. The morphology and printing abilities were investigated, and biological tests were performed. Finite element analysis (FEA) was performed to predict the maximum load that the bilayer’s bioactive-biomaterials scaffold (BBBS) could carry. The presence of HA and CS/SF in the PLA/PCL structure increased cell proliferation. The FEA predicted the load carrying capacity to be up to 663.2 N. All tests indicated that it is possible for BBBS to be used in tissue engineering for AC and bone regeneration in FTAC treatment.

The aim of this research is to investigate the sequence of processes for improving the welded surface integrity of AA7075-T651 aluminum alloy joined by friction stir welding (FSW). The improvement processes that will be investigated herein include mechanical surface improvement with deep rolling (DR) and post-weld heat treatment (PWHT). Therefore, this study investigated welded surface integrity, which comprises residual stress, microhardness, surface roughness, microstructure, and fatigue life (screening). The experiment consists of three sets of combinations. In the first set, only FSW was applied; in the second set, FSW was applied, followed by DR, and then PWHT processes (FSW-DR-PWHT); and in the last set, FSW was applied, followed by PWHT, and then DR processes (FSW-PWHT-DR). Fatigue testing was carried out by undertaking a four-point bending test using a bending stress of approximately 300 MPa with a test frequency of 2.5 Hz at room temperature and stress ratio R = 0. The study found that residual stress plays an important role in the fatigue life. Finally, the fatigue test showed that FSW workpieces subject to the PWHT process followed by the DR process (FSW-PWHT-DR) had the highest fatigue life, with an increase of 239% when compared with unprocessed FSW workpieces.

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This research is based on the purposes to find suitable hot compression conditions of composites materials, also to optimize mechanical and biological properties of the plate specimen. The type of composites materials under this investigation are bio-polymers (polylactic acid: PLA) and bio-ceramic (Hydroxyapatite: HA). In this research, the term “The design of the experiment (DOE)” was implemented to find the relation between forming factors including the ratio of HA ratio, molding temperature, and molding pressure. The result showed that the optimum conditions of the bending test were at 5%wt. of HA, 160 °C, 7 MPa of molding temperature and pressure respectively. Biodegradation rate of a specimen was 0.0175 g/day and the specimens acquired a good biocompatibility and they were non-toxic to living cells.