OPTIMIZATION OF PROCESS PARAMETERS DURING CO-CURE OF HONEYCOMB SANDWICH STRUCTURES

2021 ◽  
Author(s):  
NAVID NIKNAFS KERMANI, ◽  
PAVEL SIMACEK ◽  
SURESH G. ADVANI
Keyword(s):  
Process Parameters ◽  
Volume Fraction ◽  
Sandwich Structures ◽  
Bond Line ◽  
Temperature Cycle ◽  
Cure Process ◽  
Premature Failure ◽  
Cure Cycle ◽  
High Dependency ◽  
Honeycomb Sandwich

Honeycomb sandwich structures are co-cured to bond partially cured thermoset prepreg facesheets with an adhesive layer to both sides of the honeycomb core under a pre-defined pressure and temperature cycle in an autoclave. High dependency of the co-cure process on the materials and process parameters makes it susceptible to defect such as poorly consolidated facesheet and highly porous bondline which can cause premature failure of the structure. The temperature and pressure in the autoclave and pressure in the vacuum bag are the parameters that describe the cure cycle of the process. In this work, an optimization of the process cycle for the co-cure process of sandwich structures that maximizes the fiber volume fraction within the prepreg and reduces the porosity is presented. The objective function is constructed to reflect the quality of both the facesheet consolidation and bond-line porosity. The Surrogate Optimization Algorithm is employed to find the cure cycle resulting in the highest facesheet consolidation level and the lowest porosity within the bond-line.

scholarly journals Path-dependent bond-line evolution in equilibrated core honeycomb sandwich structures

2020 ◽  
Vol 6 (3) ◽  
pp. 127-141
Author(s):  
Daniel Zebrine ◽  
Mark Anders ◽  
Timotei Centea ◽  
Steven Nutt
Keyword(s):  
Sandwich Structures ◽  
Bond Line ◽  
Honeycomb Sandwich ◽  
Path Dependent

Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

2021 ◽  
pp. 146442072199749
Author(s):  
H Geramizadeh ◽  
S Dariushi ◽  
S Jedari Salami
Keyword(s):  
Energy Absorption ◽  
Sandwich Structures ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
The Novel ◽  
Energy Absorption Capacity ◽  
Fused Deposition ◽  
Honeycomb Sandwich ◽  
Out Of Plane ◽  
Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

scholarly journals Post-Processing of Cold Sprayed Ti-6Al-4V Coatings by Mechanical Peening

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1038
Author(s):  
Niroj Maharjan ◽  
Ayan Bhowmik ◽  
Chunwai Kum ◽  
Jiakun Hu ◽  
Yongjing Yang ◽  
...  
Keyword(s):  
Surface Integrity ◽  
Volume Fraction ◽  
Aerospace Industry ◽  
Metal Alloys ◽  
High Porosity ◽  
Post Processing ◽  
Premature Failure ◽  
Additive Manufacturing Technology ◽  
Hammer Peening ◽  
Compressive Residual Stresses

Cold spray is an emerging additive manufacturing technology used in the aerospace industry to repair damaged components made of expensive metal alloys. The cold sprayed layer is prone to surface integrity issues such as high porosity and inadequate bonding at the substrate-coating interface, which may cause premature failure of the repaired component. This study explored the use of mechanical peening as a post-processing method to improve the surface integrity of the cold sprayed component by modifying mechanical properties near the surface. Two mechanical peening processes, deep cold rolling (DCR) and controlled hammer peening (CHP), were utilized to improve cold sprayed Ti-6Al-4V coating on the Ti-6Al-4V substrate. Experimental results indicate that DCR and CHP increase the strength of the bond between the coating and substrate due to introduction of compressive residual stresses. In addition, porosity is also reduced by as much as 71%. The improvement is attributed to both the compacting effect of peening processes and the increment in the volume fraction of deformed regions.

scholarly journals Diffusion Bonding of a Cold-Worked Ni-Base Superalloy

2018 ◽  
Author(s):  
Sung Hwan Kim ◽  
Chaewon Kim ◽  
Changheui Jang
Keyword(s):  
Diffusion Bonding ◽  
Brittle Failure ◽  
Room Temperature ◽  
Boundary Diffusion ◽  
Cold Work ◽  
Bond Line ◽  
Alloy 600 ◽  
Premature Failure ◽  
Cold Worked ◽  
Base Superalloy

Diffusion bonding was conducted on cold-worked Alloy 600. Cold-work of 50 % was applied prior to diffusion bonding in order to incite recrystallization and limit grain growth. Tensile testing was conducted at room temperature and 550 °C for evaluation of joint efficiency, while premature brittle failure at the bond-line was observed for most diffusion bonding conditions. It was found that such premature failure was related to a planar bond-line that indicated lack of grain boundary diffusion across the bonding surfaces. Additional application of post-bond heat treatments did not result in significant bond-line migration. Microstructural analyses revealed the existence of Cr-rich carbides and Ti-rich precipitates along the bond-line, which prevented bond-line migration by acting as pinning points.

Microwave Absorbing Properties of Lightweight Nanocomposite/Honeycomb Sandwich Structures

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
A. A. Khurram ◽  
Sobia A. Rakha ◽  
Naveed Ali ◽  
M. T. Asim ◽  
Zhang Guorui ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Epoxy Composite ◽  
Sandwich Structures ◽  
Wide Band ◽  
Wide Frequency Range ◽  
Simulation Software ◽  
Multiwalled Carbon ◽  
Thin Glass ◽  
Honeycomb Sandwich ◽  
Honeycomb Cores

Thin glass-fiber/epoxy-composite sheets filled with multiwalled carbon nanotubes (MWCNTs) are manufactured to make lightweight honeycomb sandwich microwave absorbers. A multilayered sandwich structure of thin nanocomposite sheets and honeycomb spacers have been also proposed and developed to work in a wide frequency range. The nanocomposite sheets are prepared from 0.5, 1.0, 1.5, 2.0, and 2.5 wt. % of MWCNTs. A commercially available simulation software computer simulation technology (CST) microwave studio was used for the designing and development of radar absorbing structure (RAS) composed of MWCNTs/glass-fiber/epoxy-composite sheets and honeycomb cores. The measurements of return loss (RL) from sandwich structures with 5 mm and 20 mm honeycomb cores in the Ku band (11–17 GHz) show that maximum RL is achieved at 11 GHz and 16 GHz, respectively. The stacking of three nanocomposite sheets and three 5 mm-thick honeycomb spacers produced a wide band microwave absorber with −10 dB RL over 9 GHz bandwidth.

The Research of Spraying SiC/Cu Electronic Packaging Composites

2011 ◽  
Vol 284-286 ◽  
pp. 620-623
Author(s):  
Ming Hu ◽  
Jing Gao ◽  
Yun Long Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Process Parameters ◽  
Electronic Packaging ◽  
High Speed ◽  
Volume Fraction ◽  
Flame Spraying ◽  
Packaging Materials ◽  
Excellent Performance ◽  
Chemical Plating

The SiC/Cu electronic packaging composites with excellent performance were successfully prepared by the chemical plating copper on the surface of SiC powders and high-speed flame spraying technology. The results showed that the homogeneous dense coated layers can be obtained on the surface of SiC powder by optimizing process parameters. The volume fraction of SiC powders in the composites could significantly increase and figure was beyond 55vol% after spraying Copper. The SiC and Cu were the main phases in the spraying SiC/Cu electronic packaging composite, at the same time Cu2O can be tested as the trace phase. The interface combination properties of SiC/Cu in the hot-pressed samples can obviously improve. The thermal expansion coefficient and thermal conductivity of SiC/Cu electronic packaging composite basic can satisfy the requirements for electronic packaging materials.

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