Challenges in Designing and Manufacturing Fully Optimized Functional Gradient Material Objects

Author(s):  
Anthony Garland ◽  
Greg Mocko ◽  
Georges Fadel

Functionally Gradient Materials (FGM) smoothly transition from one material to another within a single object, allowing engineers to customize the physical response of different regions of the object by modifying the material composition at each region. New FGM research makes design, manufacturing, and use of FGM objects a promising alternative to homogeneous objects or composites with one direction of gradation. Heterogeneous anisotropic artifacts can be manufactured with specific 3D printing processes and potentially bring significant increases in functionalities. However, many challenges exist while designing and manufacturing these objects. This paper explores these challenges and suggests needed research. In particular the ability to model FGM objects, setup and run optimization algorithms, create manufacturing process plans, and control the manufacturing process all need more research and better software tools. In addition, researchers must rigorously test optimally designed FGM objects in order to validate the FGM object properties and the FGM design process before adoption of FGM objects by industry is likely to occur.

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6521
Author(s):  
Yeabsra Mekdim Hailu ◽  
Aamer Nazir ◽  
Shang-Chih Lin ◽  
Jeng-Ywan Jeng

Functionally graded lattice structures have attracted much attention in engineering due to their excellent mechanical performance resulting from their optimized and application-specific properties. These structures are inspired by nature and are important for a lightweight yet efficient and optimal functionality. They have enhanced mechanical properties over the uniform density counterparts because of their graded design, making them preferable for many applications. Several studies were carried out to investigate the mechanical properties of graded density lattice structures subjected to different types of loadings mainly related to tensile, compression, and fatigue responses. In applications related to biomedical, automotive, and aerospace sectors, dynamic bending and rotational stresses are critical load components. Therefore, the study of torsional properties of functionally gradient lattice structures will contribute to a better implementation of lattice structures in several sectors. In this study, several functionally gradient triply periodic minimal surfaces structures and strut-based lattice structures were designed in cylindrical shapes having 40% relative density. The HP Multi Jet Fusion 4200 3D printer was used to fabricate all specimens for the experimental study. A torsional experiment until the failure of each structure was conducted to investigate properties of the lattice structures such as torsional stiffness, energy absorption, and failure characteristics. The results showed that the stiffness and energy absorption of structures can be improved by an effective material distribution that corresponds to the stress concentration due to torsional load. The TPMS based functionally gradient design showed a 35% increase in torsional stiffness and 15% increase in the ultimate shear strength compared to their uniform counterparts. In addition, results also revealed that an effective material distribution affects the failure mechanism of the lattice structures and delays the plastic deformation, increasing their resistance to torsional loads.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ji-Young Jeong ◽  
Je-Ryung Lee ◽  
Hyeonjin Park ◽  
Joonkyo Jung ◽  
Doo-Sun Choi ◽  
...  

AbstractMicrowave absorbers using conductive ink are generally fabricated by printing an array pattern on a substrate to generate electromagnetic fields. However, screen printing processes are difficult to vary the sheet resistance values for different regions of the pattern on the same layer, because the printing process deposits materials at the same height over the entire surface of substrate. In this study, a promising manufacturing process was suggested for engraved resistive double square loop arrays with ultra-wide bandwidth microwave. The developed manufacturing process consists of a micro-end-milling, inking, and planing processes. A 144-number of double square loop array was precisely machined on a polymethyl methacrylate workpiece with the micro-end-milling process. After engraving array structures, the machined surface was completely covered with the developed conductive carbon ink with a sheet resistance of 15 Ω/sq. It was cured at room temperature. Excluding the ink that filled the machined double square loop array, overflowed ink was removed with the planing process to achieve full filled and isolated resistive array patterns. The fabricated microwave absorber showed a small radar cross-section with reflectance less than − 10 dB in the frequency band range of 8.0–14.6 GHz.


Procedia CIRP ◽  
2021 ◽  
Vol 96 ◽  
pp. 57-62
Author(s):  
Alexios Papacharalampopoulos ◽  
Harry Bikas ◽  
Christos Michail ◽  
Panagiotis Stavropoulos

2007 ◽  
Vol 361-363 ◽  
pp. 903-906 ◽  
Author(s):  
R. Gabbrielli ◽  
I.G. Turner ◽  
Chris R. Bowen

The demand in the medical industry for load bearing materials is ever increasing. The techniques currently used for the manufacture of such materials are not optimized in terms of porosity and mechanical strength. This study adopts a microstructural shape design approach to the production of open porous materials, which utilizes spatial periodicity as a simple way to generate the models. A set of triply periodic surfaces expressed via trigonometric functions in the implicit form are presented. A geometric description of the topology of the microstructure is necessary when macroscopic properties such as mechanical strength, stiffness and isotropy are required to be optimised for a given value of volume fraction. A distinction between the families of structures produced is made on the basis of topology. The models generated have been used successfully to manufacture both a range of structures with different volume fractions of pores and samples of functional gradient material using rapid prototyping.


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