Figure 9 - uploaded by Omar Ahmed Mohamed
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Citations
... Additive Manufacturing (AM), also known as 3D printing, is an evolving technology that constructs products by progressively adding materials layer by layer [1]. This method has demonstrated efficient performance across various materials, geometries, and manufacturing techniques, offering numerous advantages over traditional manufacturing processes. ...
This study investigates the influence of ultraviolet (UV) radiation on the mechanical properties of Fused Deposition Modeling (FDM) 3D printed materials, specifically polycarbonate (PC) and polylactic acid (PLA) specimens. The research involves conducting experiments on five test specimens of each material exposed to UV radiation and comparing their mechanical properties to those of five control specimens that remain unexposed. The results reveal a significant mean difference between the mechanical properties of the control and UV-exposed materials. UV radiation caused a decrease in tensile strength for the PC material, while the PLA material exhibited an increase in tensile strength. The impact of UV radiation on PLA was more substantial compared to PC. Flexural strength testing showed an enhancement in strength for the UV-treated materials, with UV treatment having a greater influence on the flexural strength of PLA compared to PC. The mechanical properties of PLA were more significantly impacted by UV radiation than those of PC. The study findings suggest that PC and PLA materials exhibit different responses to UV exposure, which may have implications for their practical applications. Further research is needed to fully understand the underlying mechanisms governing these divergent responses and to optimize the performance of each material under UV radiation.
... The remarkable size reduction enabled by the introduction to the waveguide metamaterial resonators meets the 3D-printing technique on the basis of fused deposition modeling (FDM), turning into extra weight reduction. The metallic WG ZOR filter has been transformed to its 3D-printed version, manufactured as in Figure 9a, which was introduced by [18]. Using the 3D printer of FDM shown in Figure 9b, a polymer named PC (Polycarbonate) is additively grown to become the geometry appearing in Figure 9c,d owing to the filament projected by the tip of Stratasys (Fortus 450 mc) [19]. ...
... ContPrototyped eighth-order WG ZOR BPF via 3D-printing process: (a) basic idea of FDM[18], (b) the 3D printer employed here and its working mechanism[19], (c) front view of the inside garnished by the flange body, (d) top view of the 3D-printed filter, (e) our 3D-printed WG filter under test and (f) S11 and S21. ...
In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG ZOR) are designed on the cross section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG ZOR is shorter than one-eighth of a wavelength. A substantial reduction in the size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band that is much longer than that in K- or Ka-bands. The proposed metamaterial filter is realized as a 3D-printed structure to be lighter and thus more suitable for low earth orbit (LEO) satellites. An X-band of 7.25–7.75 GHz is chosen to verify the method as the passband with an attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured in two ways, namely the CNC-milling technique and metal coating–added 3D printing. The design is carried out with a geometrical parameter of not 10−2 mm but rather 10-1 mm, which is good for manufacturers but challenging for component designers. The measurement of the manufactured metal waveguide filters reveals that the passband has about ≤1 dB and ≤−15 dB as the insertion loss and the reflection coefficient, respectively, and the stopband has an attenuation of ≤−40 dB, which are in good agreement with the results of the circuit and the simulation. The proposed filter has a length of 14 cm as the eighth-order BPF, but the conventional waveguide is 20 cm as the seventh-order BPF for the same area of the cross section.
... U disertaciji [4] predstavljeni su rezultati eksperimentalnog istraživanja uticaja odabranih parametara izrade kod FDM postupka 3D printanja (visina sloja, razmak između rastera, ugao rastera, orijentaciju izrade, širinu rastera i broj kontura) na različite osobine printanog uzorka kao što su: dimenziona tačnost, vrijeme izrade, količina utrošenog materijala, tribološke osobine i dinamičke mehaničke osobine kod PC-ABS materijala. Analiziran je zaseban i interaktivan uticaj FDM parametara na navedene osobine, kroz sveobuhvatno istraživanje korištenjem različitog dizajna eksperimenta i statističkih analiza kao što su metode "IV-optimal design", DSD, analizom varijanse, analizom višestruke regresije i PLS (engl. ...
... Oblik ispune; 2 Gustina ispune;3 Ugao ispune4 Interakcije između parametara dizajna ispune Na osnovu rezultata ANOVA analize, za sva četiri ispitivana materijala, može se zaključiti da su oblik ispune, gustina ispune kao i njihova interakcija značajni faktori dizajna ispune i bitno utiču na ukupno vrijeme printanja uzorka, količinu potrošenog materijala kao i vrijeme printanja strukture ispune. Također, na osnovu -vrijednosti (> 0,05) zaključuje se da kod sva četiri materijala ugao ispune, te interakcije ugla ispune sa gustinom i oblikom ispune, nemaju značajan uticaj na ukupno vrijeme printanja uzorka, količinu potrošenog materijala kao i vrijeme printanja strukture ispune. ...
Predmet doktorske disertacije je teoretsko-eksperimentalno istraživanje uticaja dizajna ispune (eng. infill design) na osobine FDM printanih polimernih materijala sa strukturom ispune. S tim u vezi, jedan od primarnih ciljeva istraživanja je razvoj metodologije ispitivanja s ciljem dobivanja matematskih formulacija (matematskih modela) za procjenu zateznih mehaničkih osobina u zavisnosti od dizajna ispune (oblik, gustina i ugao).
Na osnovu teoretskog istraživanja predstavljen je detaljan pregled dosadašnjih istraživanja na temu uticaja dizajna ispune na osobine FDM printanih polimernih materijala. Dat je pregled materijala za aditivne tehnologije sa fokusom na FDM polimerne materijale. Predstavljeni su fizikalni aspekti pri formiranju FDM printanih polimernih materijala, te su predstavljeni uticajni faktori na osobine istih. Opisani su FDM printani polimerni materijali sa strukturom ispune, te navedene njihove karakteristike. Opisan je način ispitivanja mehaničkih osobina FDM printanih materijala sa i bez strukture ispune, pri čemu su analizirani standardi koji se najčešće koriste pri ispitivanju istih.
U eksperimentalnom dijelu, urađeno je ispitivanje zateznih mehaničkih ispitivanja PLA, Tough PLA, PC i PETG FDM printanih polimernih materijala sa strukturom ispune. Analiziran je uticaj 7 različitih oblika ispune, 4 različite gustine i 4 ugla ispune u odnosu na smjer opterećenja, pri čemu su ukupno analizirana 1344 ispitna uzorka. Prikazani su dijagrami napon-deformacija za svaki materijal prema obliku ispune. Također, rezultati su predstavljeni i uspoređeni kroz histograme, gdje je za svaki oblik ispune prikazan uticaj gustine i ugla ispune na maksimalnu silu 𝐹𝑚 i modul elastičnosti 𝐸. Izvršena je i usporedba mehaničkih osobina samih materijala.
Primjenom dizajna eksperimenta, metodologijom potpunog faktorijalnog dizajna, analiziran je uticaj dizajna ispune na maksimalnu silu 𝐹𝑚 i modul elastičnosti 𝐸 za svaki materijal, te su razvijeni matematski modeli za predviđanje istih. Za ocjenu tačnosti matematskog modela korišteni su koeficijent determinacije 𝑅2 (R-sq), 𝑅2 prilagođeni (R-sq adj) i 𝑅2 predviđeni (R-sq pred). Adekvatnost razvijenih matematskih modela, provjerena je pomoću analize reziduala, gdje je posmatran histogram i grafik normalne vjerovatnoće reziduala. Slaganje eksperimentalnih i modelom predviđenih vrijednosti izvršeno je zaračunavanjem koeficijenta korelacije R. Kako bi se provjerio i procijenio uticaj i značaj faktora (oblik, gustina i ugao ispune), korištena je analiza varijanse (ANOVA). Također, predstavljeni su dijagrami glavnih efekata i interakcija. Primjenom Tukey testa izvršena je analiza višestrukim upoređivanjem srednjih vrijednosti izlaza za sve nivoe faktora. Primjenom 3D dijagrama i dijagrama kontura, grafički je predstavljen zajednički uticaj gustine i ugla ispune na maksimalnu silu 𝐹𝑚 i modul elastičnosti 𝐸. Urađena je i validacija matematskog modela kao i optimizacija maksimalne sile 𝐹𝑚 i modula elastičnosti 𝐸.
Na kraju je urađena tehno-ekonomska analiza primjene strukture ispune kod FDM printanih polimernih materijala. Analiziran je uticaj oblika, gustine i ugla ispune na ukupno vrijeme printanja ispitnog uzorka, količina utrošenog materijala tokom printanja, kao i vrijeme printanja strukture ispune. Zatim je kroz dijagrame predstavljena usporedba izrade proizvoda, u ovom slučaju ispitnog uzorka, sa i bez (100% gustina ispune) primjene strukture ispune. Analizirana je ušteda ukupnog vremena printanja kao i količine potrošenog materijala pri promjeni gustine ispune, kao najutjecajnijeg parametra dizajna ispune na iste.
... The dynamic behaviour analysis of printed mechanical structures has gained importance in recent years [10,12,13]. Indeed, these printed structures (solid parts) offer good mechanical performance and a reduced weight [14], unlike the isotropic and composite components. ...
The aim of this paper is to investigate experimentally the effect of large vibration of a cantilever and a fully free rectangular plate made by a Fused Filament Fabrication process. Furthermore, this investigation attempts to compare our measurements and those obtained in the literature experimentally. For this purpose, a test rig was designed and manufactured for all experimental trials. The plate was excited randomly and harmonically at large displacement respectively, to obtain the linear and non-linear frequencies parameter. The non-linear dynamic behaviour of our structure at forced vibration is figured by exciting the plate at large displacement. The dependence of frequency and amplitude vibration are examined for the first, second, and third mode shapes. The non-linear dynamic behaviour of cantilever plates is compared with literature to illustrate the convergence of our results by using our specific mechanical properties, printing parameters, and process. Furthermore, the non-dimensional comparison is shown by 33.38%, 5.83%, and 20.58% for the first, second, and third mode shapes, respectively. Experimental tests will be performed on a 3D-printed metal plate to improve the present work. This work is intended to determine the dynamic proprieties of our parts in order to manufacture a safe and comfort machine. Actually, the dynamic behaviour of our 3D printing plates is compared with the obtained in the case of the isotropic plate for the aim to predict the convergence of both structures.
... Direct metal deposition process(Mohamed 2017). For a color version of this figure, seewww.iste.co.uk/kumar/materials.zip ...
This chapter explains an appraisal of the methodologies and suitable materials used in additive manufacturing (AM) for advancing the aerospace industry with the performances of topological and material optimization, design integration and part consolidation that promotes profitable quantity and quality products. It discusses several 3D printing methods and the use of different materials and their applications in the aerospace industry. The prominent process of AM is classified into the following seven types, namely laser beam melting, electron beam melting, selective laser melting, direct metal laser sintering, laser metal fusion, and direct metal deposition. The materials play a predominant role in AM, which are considered for engineered operational applications. AM contributes its foremost capability to serving the aerospace industry, because this industry faced a great challenge to reduce the weight and size of components in order to avoid dangers and promote safety and durability.
... Şekil 1. Eİ prosesinin işlem basamakları [26,27] Şekil 2. Eİ teknolojisinin sınıflandırılması [29] 964 Basım sırasında, her katmanın üzerine bir sonraki katman eklenerek, katmanlı bir yapı oluşturulur. İşlem sonrasında, kullanılan yönteme ve malzemeye bağlı olarak ısıl işlem, yüzey işlemleri gibi bitirme işlemleri tercih edilebilmektedir. ...
Objective
To describe the process of three‐dimensional printing in epilepsy surgery using three different methods: low‐force stereolithography (SLA), filament deposition modeling (FDM), and Polyjet Stratasys, while comparing them in terms of printing efficiency, cost, and clinical utility. MRI and CT images of patient anatomy have been limited to review in the two‐dimensional plane, which provides only partial representation of intricate intracranial structures. There has been growing interest in 3D printing of physical models of this complex anatomy to be used as an educational tool and for surgical visualization. One specific application is in epilepsy surgery where there are challenges in visualizing complex intracranial anatomy in relation to implanted surgical tools.
Methods
MRI and CT data from patients with refractory epilepsy from a single center that underwent surgery are converted into 3D volumes, or stereolithography files. These were then printed using three popular 3D printing methods: SLA, FDM, and Polyjet. Faculty were surveyed on the impact of 3D modeling on the surgical planning process.
Results
All three methods generated physical models with an increasing degree of resolution, transparency, and clinical utility directly related to cost of production and accurate representation of anatomy. Polyjet models were the most transparent and clearly represented intricate implanted electrodes but had the highest associated cost. FDM produced relatively inexpensive models that, however, were nearly completely opaque, limiting clinical utility. SLA produced economical and highly transparent models but was limited by single material capacity.
Significance
Three‐dimensional printing of patient‐specific anatomy is feasible with a variety of printing methods. The clinical utility of lower‐cost methods is limited by model transparency and lack of multi‐material overlay respectively. Polyjet successfully generated transparent models with high resolution of internal structures but is cost‐prohibitive. Further research needs to be done to explore cost‐saving methods of modeling.
4D bioprinting is the next-generation additive manufacturing-based fabrication platform employed to construct intricate, adaptive, and dynamic soft and hard tissue structures as well as biomedical devices by using stimuli-responsive materials, especially shape memory polymers (SMPs) and hydrogels, which possess desirable biomechanical characteristics. In the last few years, numerous efforts have been made by 4D printing community to develop novel stimuli-responsive polymeric materials by considering their biomedical perspective. This review presents an up-to-date overview of 4D bioprinting technology incorporating bioprinting materials, functionalities of biomaterials as well as the focused approach towards different tissue engineering and regenerative medicine (TERM) applications, including bone, cardiac, neural, cartilage, drug delivery systems, and other high-value biomedical devices. It also addresses current limitations and challenges in 4D bioprinting technology to provide a basis for foreseeable advancements for TERM applications that will prove helpful for their successful utilization in clinical settings.
