Analytical modelling of in-situ layer-wise defect detection in 3D Printed parts: Additive Manufacturing

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.This study analyses a software algorithm developed on MATLAB, which can be used to examine fused filament fabrication-based 3D printed materials for porosity and other defects that might affect the mechanical property of the final component under manufacture or the general aesthetic quality of a product. An in-depth literature review into the 3D printed materials reveals a rapidly increasing trend in its application in the industrial sector. Hence the quality of manufactured products cannot be compromised. Despite much research found to be done on this subject, there is still little or no work reported on porosity or defect detection in 3D printed components during (real-time) or after manufacturing operation. The algorithm developed in this study is tested for two different 3-D object geometry and the same filament color. The results showed that the algorithm effectively detected the presence or absence of defects in a 3D printed part geometry and filament colors. Hence, this technique can be generalized to a considerable range of 3-D printer geometries, which solve material wastages by spotting defects during the workpieces layer-wise manufacturing process, thereby improving the economic advantages of additive manufacturing

Microstructural Evaluation of Aluminium Alloy A365 T6 in Machining Operation

The optimum cutting parameters such as cutting depth, feed rate, cutting speed and magnitude of the cutting force for A356 T6 was determined concerning the microstructural detail of the material. Novel test analyses were carried out, which include mechanical evaluation of the materials for density, glass transition temperature, tensile and compression stress, frequency analysis and optimisation as well as the functional analytic behaviour of the samples. The further analytical structure of the particle was performed, evaluating the surface luminance structure and the profile structure. The cross-sectional filter profile of the sample was extracted, and analyses of Firestone curve for the Gaussian filter checking the roughness and waviness profile of the structure on aluminium alloy A356T6 is proposed. A load cell dynamometer was used to measure different parameters with the combination of a conditioning signal system, a data acquisition system and a computer with visualised software. This allowed recording the variations of the main cutting force throughout the mechanised pieces under different cutting parameters. A carbide inserted tool with triangular geometry was used. The result shows that the lowest optimum cutting force is 71.123 N at 75 m/min cutting speed, 0.08 mm/rev feed rate and a 1.0 mm depth of cut. The maximum optimum cutting force for good surface finishing is 274.87 N which must be at a cutting speed of 40 m/min, 0.325 mm/rev feed rate and the same 1.0 mm depth of cut

Nanostructural interface and strength of polymer composite scaffolds applied to intervertebral bone

The pores of bone tissue that play an important part in bone regeneration can emulate the areas of nanoparticles from porous scaffolds. This work evaluated a novel designed and developed nanostructure surface of polyetheretherketone-reduced graphene oxide, calcium hydroxyapatite (PEEK-rGO-cHAp) composite scaffolds of four different lattice structures. The scaffolds were fabricated through fused deposition modeling (FDM), as rGO-cHAp composite was coated on PEEK. The composite scaffolds’ mechanical strength and surface microstructure were studied, using different nanostructure methods of unit cell homogenization and tensile test. The homogenization method for the four lattice structures was designed and analyzed to mimic spine bone structure. A new approach was introduced to homogenize the mechanical characteristics of a periodical lattice of 3D printing structures based on a semi-rigid frame unit cell. They were taking into consideration the impact of geometric approximation errors and joint tightening. A typical frame element with semi-rigid is integrated to assess combined stiffening effects in a discrete homogenization process. The analysis was performed by considering the fundamental unit cell as a scaffold that defined the periodic pattern. Also, this study created an avenue to examine and improve the interfacial bonding between PEEK and rGO-cHAp scaffolds for biocompatibility and degradability, using surface functionalization techniques. The purpose of this research is to compare the manufacturing processes in a model of intervertebral spacer, describe the characteristics of PEEK biomaterial, and explain some parameters related to its processing. In addition to its manufacturing part, a brief theory on the anatomy of the spine region was also presented. To establish its practical applications and benefits in tissue engineering, this study focused on the cervical region via a simulation approach using an anterior method.</p

3D printing of PEEK–cHAp scaffold for medical bone implant

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The major drawback associated with PEEK implants is their biologically inert surface, which caused unsatisfactory cellular response and poor adhesion between the implants and surrounding soft tissues against proper bone growth. In this study, polyetheretherketone (PEEK) was incorporated with calcium hydroxyapatite (cHAp) to fabricate a PEEK–cHAp biocomposite, using the fused deposition modeling (FDM) method and a surface treatment strategy to create microporous architectures onto the filaments of PEEK lattice scaffold. Also, nanostructure and morphological tests of the PEEK–cHAp biocomposite were modeled and analyzed on the FDM-printed PEEK–cHAp biocomposite sample to evaluate its mechanical and thermal strengths as well as in vitro cytotoxicity via a scanning electron microscope (SEM). A technique was used innovatively to create and investigate the porous nanostructure of the PEEK with controlled pore size and distribution to promote cell penetration and biological integration of the PEEK–cHAp into the tissue. In vivo tests demonstrated that the surface-treated micropores facilitated the adhesion of newly regenerated soft tissues to form tight implant–tissue interfacial bonding between the cHAp and PEEK. The results of the cell culture depicted that PEEK–cHAp exhibited better cell proliferation attachment spreading and higher alkaline phosphatase activity than PEEK alone. Apatite islands formed on the PEEK–cHAp composite after immersion in simulated body fluid of Dulbecco's modified Eagle medium (DMEM) for 14 days and grew continuously with more or extended periods. The microstructure treatment of the crystallinity of PEEK was comparatively and significantly different from the PEEK–cHAp sample, indicating a better treatment of PEEK–cHAp. The in vitro results obtained from the PEEK–cHAp biocomposite material showed its biodegradability and performance suitability for bone implants. This study has potential applications in the field of biomedical engineering to strengthen the conceptual knowledge of FDM and medical implants fabricated from PEEK–cHAp biocomposite materials

Lattice design and 3D-printing of PEEK with Ca10(OH)(PO4)3 and in-vitro bio-composite for bone implant

© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/.The addition of biomaterials such as Calcium hydroxyapatite (cHAp) and incorporation of porosity into poly-ether-ether-ketone (PEEK) are effective ways to improve bone-implant interfaces and osseointegration of PEEK composite. Hence, the morphological effects of nanocomposite on surfaces biocompatibility of a newly fabricated composite of PEEK polymer and cHAp for a bone implant, using additive manufacturing (AM) were investigated. Fused deposition modeling (FDM) method and a surface treatment strategy were employed to create a microporous scaffold. PEEK osteointegration was slow and, therefore, it was accelerated by surface coatings with the incorporation of bioactive cHAp, with enhanced mechanical and biological behaviors for bone implants. Characterization of the new PEEK/cHAp composite was done by X-ray diffraction (XRD), differential scanning calorimetry (DSC), mechanical tests of traction and flexion, thermal dynamic mechanical analysis (DMA). Also, the PEEK/cHAp induced the formation of apatite after immersion in the simulated body fluid of DMEM for different days to check its biological bioactivity for an implant. In-vivo results depicted that the osseointegration and the biological activity around the PEEK/cHAp composite were higher than that of PEEK. The increase in the mechanical performance of cHAp-coated PEEK can be attributed to the increase in the degree of crystallinity and accumulation of residual polymer.Peer reviewe