MANUFACTURING OF AIRCRAFT WING STIFFENERS USING 4D PRINTING OF COMPOSITES

2021 ◽  
Author(s):  
SUONG VAN HOA ◽  
BHARGAVI REDDY ◽  
DANIEL IOSIF ROSCA
Keyword(s):  
Room Temperature ◽  
Complex Structures ◽  
4D Printing ◽  
Aircraft Wing ◽  
Final Structure

This paper presents the procedure to make omega stiffeners using the method of 4D printing of composites. The method allows the manufacturing of complex structures without the need for a complex mold. Instead, flat layers of composite prepregs are laid on a flat mold. Due to the anisotropy of the different layers in the laminates, the stack of prepregs will change from its flat configuration into the omega shape upon curing and cooling to room temperature. The cavity is filled with foam to make the final structure.

scholarly journals 4D Printing: A Review on Recent Progresses

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 796 ◽  
Author(s):  
Honghui Chu ◽  
Wenguang Yang ◽  
Lujing Sun ◽  
Shuxiang Cai ◽  
Rendi Yang ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Three Dimensional ◽  
Complex Structures ◽  
Future Prospects ◽  
4D Printing ◽  
Stimulation Method ◽  
Shape Property ◽  
External Stimuli

Since the late 1980s, additive manufacturing (AM), commonly known as three-dimensional (3D) printing, has been gradually popularized. However, the microstructures fabricated using 3D printing is static. To overcome this challenge, four-dimensional (4D) printing which defined as fabricating a complex spontaneous structure that changes with time respond in an intended manner to external stimuli. 4D printing originates in 3D printing, but beyond 3D printing. Although 4D printing is mainly based on 3D printing and become an branch of additive manufacturing, the fabricated objects are no longer static and can be transformed into complex structures by changing the size, shape, property and functionality under external stimuli, which makes 3D printing alive. Herein, recent major progresses in 4D printing are reviewed, including AM technologies for 4D printing, stimulation method, materials and applications. In addition, the current challenges and future prospects of 4D printing were highlighted.

scholarly journals 4D Printing Self-Morphing Structures

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1353 ◽  
Author(s):  
Mahdi Bodaghi ◽  
Reza Noroozi ◽  
Ali Zolfagharian ◽  
Mohamad Fotouhi ◽  
Saeed Norouzi
Keyword(s):  
Composite Structures ◽  
Fused Deposition Modeling ◽  
Functionally Graded ◽  
Complex Structures ◽  
Mechanical Behaviors ◽  
4D Printing ◽  
Digital Tool ◽  
Fused Deposition ◽  
Straightforward Method ◽  
Deposition Modeling

The main objective of this paper is to introduce complex structures with self-bending/morphing/rolling features fabricated by 4D printing technology, and replicate their thermo-mechanical behaviors using a simple computational tool. Fused deposition modeling (FDM) is implemented to fabricate adaptive composite structures with performance-driven functionality built directly into materials. Structural primitives with self-bending 1D-to-2D features are first developed by functionally graded 4D printing. They are then employed as actuation elements to design complex structures that show 2D-to-3D shape-shifting by self-bending/morphing. The effects of printing speed on the self-bending/morphing characteristics are investigated in detail. Thermo-mechanical behaviors of the 4D-printed structures are simulated by introducing a straightforward method into the commercial finite element (FE) software package of Abaqus that is much simpler than writing a user-defined material subroutine or an in-house FE code. The high accuracy of the proposed method is verified by a comparison study with experiments and numerical results obtained from an in-house FE solution. Finally, the developed digital tool is implemented to engineer several practical self-morphing/rolling structures.

scholarly journals Room temperature structure and transport properties of the incommensurate modulated LaNb0.88W0.12O4.06

2019 ◽  
Vol 48 (5) ◽  
pp. 1633-1646 ◽  
Author(s):  
Cheng Li ◽  
Stevin S. Pramana ◽  
Stephen J. Skinner
Keyword(s):  
Ion Transport ◽  
Transport Properties ◽  
Room Temperature ◽  
Cation Ordering ◽  
Temperature Structure ◽  
Complex Structures ◽  
Ion Conducting ◽  
Oxide Ion

Cation ordering in the modulated La(Nb,W)O4+d phases has been demonstrated and the role of W in inducing occupancy modulation to this phase discussed. This is linked with the oxide ion transport, highlighting that modulated complex structures are viable candidates for ion conducting applications.

Complementary JFET Logic for Low-Power Applications in Extreme Environments

2013 ◽  
Vol 740-742 ◽  
pp. 1052-1055
Author(s):  
H. Habib ◽  
N.G. Wright ◽  
A.B. Horsfall
Keyword(s):  
Power Dissipation ◽  
Room Temperature ◽  
Supply Voltage ◽  
Extreme Environments ◽  
Building Blocks ◽  
Silicon On Insulator ◽  
Complex Structures ◽  
Noise Margin ◽  
Static Power ◽  
Logic Functions

The static and dynamic characteristics of Complementary JFET (CJFET) logic inverter are studied across a range of temperatures and supply voltages to assess potential improvements in performance of digital logic functions for operation in extreme environments. The logic inverter is truly the core of all digital designs. The design and analysis of inverter enables the design of more complex structures, such as NAND, NOR and XOR gates. These complex structures in turn form the building blocks for modules, such as adders, multipliers and microprocessors. At 500 deg C and operating at a supply voltage of 1 V, the CJFET inverter have noise margin comparable to that of room temperature silicon and silicon on insulator CMOS inverters. Furthermore, the static power dissipation by CJFET inverter at 500 deg C is 20.6 nW which is six orders of magnitude lower than that by current SiC technologies, making CJFET technology ideal for achieving complex logic functions, far greater than a few-transistors ICs, in the nearer term.

4D Printing in Biomedical Applications: Emerging Trends and Technologies

2021 ◽  
Author(s):  
Tarun Agarwal ◽  
Sung Yun Hann ◽  
Irene Chiesa ◽  
Haitao Cui ◽  
Nehar Celikkin ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Complex Structures ◽  
4D Printing ◽  
Environmental Stimuli ◽  
Emerging Trends ◽  
Material Systems

Nature's material systems during evolution have developed the ability to respond and adapt to environmental stimuli through the generation of complex structures capable of varying their functions across the direction,...

4D Printing of Complex Structures with a Fast Response Time to Magnetic Stimulus

2018 ◽  
Vol 10 (42) ◽  
pp. 36435-36442 ◽  
Author(s):  
Pengfei Zhu ◽  
Weiyi Yang ◽  
Rong Wang ◽  
Shuang Gao ◽  
Bo Li ◽  
...  
Keyword(s):  
Response Time ◽  
Fast Response ◽  
Complex Structures ◽  
4D Printing ◽  
Fast Response Time ◽  
Magnetic Stimulus

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

1982 ◽  
Vol 40 ◽  
pp. 56-57
Author(s):  
J. N. Turner ◽  
D. N. Collins
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Dose Group ◽  
Methyl Cellulose ◽  
Uranyl Acetate ◽  
Target Organ ◽  
Office Building ◽  
Lead Citrate ◽  
Control Groups ◽  
Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

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