scholarly journals Adhesive Bonding of Aircraft Composite Structures

2021 ◽  
2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Sadik Omairey ◽  
Nithin Jayasree ◽  
Mihalis Kazilas

AbstractThe increasing use of fibre reinforced polymer composite materials in a wide range of applications increases the use of similar and dissimilar joints. Traditional joining methods such as welding, mechanical fastening and riveting are challenging in composites due to their material properties, heterogeneous nature, and layup configuration. Adhesive bonding allows flexibility in materials selection and offers improved production efficiency from product design and manufacture to final assembly, enabling cost reduction. However, the performance of adhesively bonded composite structures cannot be fully verified by inspection and testing due to the unforeseen nature of defects and manufacturing uncertainties presented in this joining method. These uncertainties can manifest as kissing bonds, porosity and voids in the adhesive. As a result, the use of adhesively bonded joints is often constrained by conservative certification requirements, limiting the potential of composite materials in weight reduction, cost-saving, and performance. There is a need to identify these uncertainties and understand their effect when designing these adhesively bonded joints. This article aims to report and categorise these uncertainties, offering the reader a reliable and inclusive source to conduct further research, such as the development of probabilistic reliability-based design optimisation, sensitivity analysis, defect detection methods and process development.


2017 ◽  
Vol 36 (10) ◽  
pp. 725-738 ◽  
Author(s):  
Xiao-Kang Li ◽  
Zhen-Guo Liu ◽  
YuChen Wei ◽  
Xiang Huang ◽  
Bing Lei

Adhesive bonding is usually used to fabricate composite structures that are hard to manufacture in one piece, however, their lightweight advantage is usually impaired by low failure strength. For high performance composite structures, bonding properties of joints dominate the failure performance and commonly are the primary target of structural optimization. Both experimental and numerical studies of failure behavior of single-lap joints with three-dimensional braided composite laminate adherends are presented in this paper. First, tensile failure tests were performed on braid-laminates single-lap joints bonded with epoxy resin. Compared with the laminates–laminates single-lap joints, the failure load of the braid–laminates single-lap joints increased by 18.4%. Then, the Finite Element Method (FEM) coupled with cohesive zone models (CZM), considering different value of overlap length (L), was used to perform the detail stress distribution of the overlap sections of SLJs. Further, damage initialization and crack growth of single-lap joints are analyzed in detail to fully characterize the failure process, and both experimental and numerical results lead to the same conclusion. Lastly, the effect of three-dimensional braided adherends’ braiding angle on braid-laminates single-lap joints’ performance was investigated, which provides suggestions for the design and optimization for adhesive bonded composite structures.


2020 ◽  
Vol 27 (2) ◽  
pp. 145-157
Author(s):  
Xiaowen Li ◽  
Zhaoyi Zhu ◽  
Yan Li ◽  
Zhe Hu

AbstractA new T-type connection structure consisting of composite sandwich plates, reinforced cores and adhesive was proposed for the construction of lightweight ships to resolve connection problems between bulkheads and decks of composite lightweight ship superstructures. Based on the design principles and mechanical properties of composite structures, the mechanical behaviour of the structure under a dangerous loading condition was investigated. In addition, the ultimate bearing capacities and damage modes were examined, the results of which demonstrated that the strength of the structure is weak, and that the adhesive and reinforced core between the face plate and the web plate is the primary weakness of the structure. A numerical simulation method was verified using the results of the mechanical tests, and five characteristic paths at the connection area were established. The stresses and displacements along the five paths were calculated using the numerical method. Then, variations in the geometric parameter and the strength and weight of the connection were summarised. The optimal angle of the adhesive bonding area is approximately 60°, which supports the optimal design and practical application of the lightweight ship adhesive-bonded connection structure.


2021 ◽  
Author(s):  
JULIETTE DUBON ◽  
GONZALO SEISDEDOSMARIANA ONTIVEROS ◽  
MARIANA ONTIVEROS ◽  
BENJAMIN BOESL ◽  
DWAYNE MCDANIEL

Adhesive bonding for composite structures offers multiple advantages over mechanical fasteners. Although the use of adhesive bonding has increased in the aerospace industry, it has still not replaced mechanical fasteners due to it being harder to inspect for damage after being manufactured/assembled, causing unreliability. Therefore, intensive quality control is needed while manufacturing to avoid weak bonds or any type of imperfection at the adhesive-adherend interface. To ensure the reliability of an adhesive bond, this project focuses on the advancement of a non-invasive field tool for adhesive quality evaluation. The tool developed is based on a B-H looper system, which can approximate the quality of an epoxy-based adhesive containing magneto-electric nanoparticles (MENs) by detecting changes in electric fields at the molecular level. Epoxy based adhesive samples containing 5 vol. % of MENs were manufactured and then scanned using the B-H looper system to correlate their magnetic signature as a function of curing time. It was determined that the magnetic signal converged between curing hours 10 and 12, indicating proper curing. Plain adhesive dogbone samples were used to determine the maximum tensile stress of the adhesive as a function of curing time, which also started converging at around the same curing hours until reaching ~41 MPa. Additionally, the evolution of the glass transition temperature of the adhesive was evaluated during the first curing hours. Convergence began at a curing time of 10 hours until reaching ~137 ⁰ C for fully cured samples. B-H looper magnetic signatures, tensile stresses testing, and glass transition temperatures were all correlated indicating a fully cured adhesive sample between 10 and 12 curing hours. These studies demonstrate the capabilities of the B-H looper system as a non-invasive inspection tool for adhesive quality.


Author(s):  
Robert L. Crane ◽  
Giles Dillingham ◽  
Brietta Oakley

2020 ◽  
Vol 13 ◽  
Author(s):  
Hiral Parikh ◽  
Kedar Pathak

Background: Innovative cooling technology is required in every field of life ranging from satellite to terrestrial applications. Novel heat rejection system is of great concern for space applications. Futuristic applications in heat pipe will involve composite structures in various ways as they offer flexibility in design with their inherent advantage of being light weight. However it remains a challenge to join a composite structure with metals. This study investigates the effect of composite section in the adiabatic region of the heat pipe and also proposes a novel approach to joining metals with composite structure. Methods: A flexible composite tube such as carbon fiber reinforced thermoplastics makes the adiabatic section. This section is adhesively bonded with the metal tubes i.e. evaporator and condenser section. Inherent roughness of the metal tube makes first layer for mechanical interlocking followed by adhesive bonding. Results: The effect of adiabatic, condenser and evaporator length, for a normal vs. composite heat pipe, on specific thermal conductivity is evaluated. Conclusion: The numerical studies confirm that the use of composite material for adiabatic section improves performance of heat pipe. It is proposed to use reinforced thermoplastic as the material for adiabatic section.


Author(s):  
Wei Huang ◽  
Lingyu Sun ◽  
Yantao Chu ◽  
Cheng Zhang ◽  
Lijun Li

Adhesive bonding of composite structures has been widely applied in aviation, aerospace, automotive and other industry fields due to the advantages of no holes required, no stress concentration, relative light weight, corrosion resistance and capability of connecting dissimilar materials. However, the strength of joining is greatly influenced by the properties of adhesives and surface treatment of adherents, the geometry and dimension of joints, loading and environmental factors, as well as the curing process and so on. When the finite element (FE) method is used to investigate the influence of above factors on structural response and to optimize the joining design, parametric modeling is required to avoid huge repetitive preprocess work at each evaluation. In this paper, the three-dimensional parametric FE models of Single Lap Joint (SLJ) between carbon fiber-reinforced polymer (CFRP) and steel was established and updated based on the published test data. Using the verified parametric model, the influence of adhesive layer thickness and relative stiffness on the joining strength is investigated, and the results provide a theoretical basis for the design of adhesion joints between CFRP and steel.


2002 ◽  
Vol 24 (3) ◽  
pp. 133 ◽  
Author(s):  
EA Armanios ◽  
RB Bucinell ◽  
DW Wilson ◽  
LJ Hart-Smith

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