Evaluation of Advanced Adhesives for Aerospace Structures (original) (raw)
Related papers
Characterization of Adhesives Bonding in Aircraft Structures
Materials
Structural adhesives play an important role in aerospace manufacturing, since they provide fewer points of stress concentration compared to faster joints. The importance of adhesives in aerospace is increasing significantly because composites are being adopted to reduce weight and manufacturing costs. Furthermore, adhesive joints are also studied to determine the crashworthiness of airframe structure, where the main task for the adhesive is not to dissipate the impact energy, but to keep joint integrity so that the impact energy can be consumed by plastic work. Starting from an extensive campaign of experimental tests, a finite element model and a methodology are implemented to develop an accurate adhesive model in a single lap shear configuration. A single lap joint finite element model is built by MSC Apex, defining two specimens of composite material connected to each other by means of an adhesive; by the Digimat multi-scale modeling solution, the composite material is treated; a...
Fracture toughness and shear behavior of composite bonded joints based on a novel aerospace adhesive
Composites Part B: Engineering, 2012
In this paper, the mechanical performance of the newly developed LMB aerospace structural adhesive has been characterized experimentally. To this end, a comparison has been performed with the Epibond 1590 A/B adhesive on the basis of the effects of thermal aging, wet aging and adhesive thickness on the fracture toughness and shear behavior (static and fatigue) of bonded joints between CFRP laminates. Mode-I and -II fracture toughness was measured through tensile and 3-point bending tests on doublecantilever beam specimen, respectively, while the shear behavior of the joints was assessed through static and fatigue double-lap shear tests. A fractographic analysis of the fracture surfaces was performed in order to detect the failure mode of the bonded joint. The experimental results show a higher fracture toughness and improved fatigue behavior for the LMB adhesive.
Nanofilled epoxy adhesive for structural aeronautic materials
Composites Part B: Engineering, 2014
The aim of this work was to develop new adhesive formulations based on epoxy/nanostructured carbon forms. Different types of nanofillers were dispersed into an epoxy matrix for developing toughened epoxy paste aeronautic adhesives. The reinforced adhesives were used for bonding carbon nanofilled/epoxy composite adherents. Data were also compared to the results obtained both for the unfilled adhesive and/or adherents. Tensile butt joint, and single lap joint samples were prepared to measure mechanical strength and adhesion properties of the different joint configurations. The inclusion of carbon nanofillers inside the epoxy adhesive caused a significant improvement in the bond strength of the joints, changing the failure mode of joints in single lap joint shear tests. Significant change of the bonding performance was observed as the weight fraction of carbon nano-fillers increased from 1.37 to 5 wt/wt%. Adhesion between nano-reinforcements and adherents substrate was studied by means of Scanning Electron Microscopy.
The Journal of Adhesion, 2013
Adhesive bonding is an interesting structural assembling technique for weight saving in modern commercial aircraft, in which the use of composites materials is increasing. In order to meet both optimization and respect of safety conception constraints, the development of accurate numerical strategies is required. Thus, improvement in the experimental characterization and in the design of reliable numerical tools for bonded assemblies is necessary. This paper presents the characterization of the elastic-plastic behaviour of four aeronautical adhesive films, consisting of two epoxy-based resins supported by two types of carrier. The characterization over a wide range of monotonic proportional tensile-shear loads is performed using a modified Arcan test device designed to strongly limit the influence of edge effects. Moreover, to obtain an accurate definition of the initial elastic limit of the adhesives, further experimental tests have been performed using a pressure vessel especially designed to study the influence of the hydrostatic stress. Inverse identification techniques using finite element analysis have been used to identify the material parameters of an elastic-plastic model based on the experimental results (the load-displacement curves). Results underline the potential of such a model to represent the non-linear behaviour of ductile adhesives under tensile/compression-shear proportional monotonic loads.
Experimental investigation of adhesive layer properties
This paper dealing with investigations of adhesive layer characteristics and it is a part of our continuous research on adhesively bonded joints. Previous experimental analysis has shown that bonding of different adherend materials using the same adhesive leads to the different behaviour of adhesive. This effect is more evident in numerical modelling of adhesively bonded joints, especially in bonding of adherends of higher yield strength. To understand how adhesives work, it is necessary to understand their mechanical properties and the chemistry used to create those properties. The object of present investigation is therefore to research cohesive and adhesive characteristics of chosen structural adhesives in correlation with adherend materials to be bonded. In particular, two- component structural epoxy adhesive and aluminium as adherend material have been tested. The knowledge of adhesive and cohesive properties of the adhesive is necessary in strength calculation of bonded joints...
Effect of Nanofillers on Adhesive Toughness Measurement
2020
Joining can be defined as a process to bond two or more parts together. In engineering, joining types are one of the most crucial part in manufacturing decision and therefore significant in design. There are a lot to be considered by engineers for the methods in assembling parts into product where it is related with the manufacturing cost, performance of product and the impact of the end product’s weight. Few things related with the decision making is by making sure the availability of the equipment, skilled labor and also the energy and cost of materials [1-3]. Basically there are three classifications of joining for assembly and joining of engineering components which are by mechanical, chemical and physical. Mechanical joining methods are usually based on localized, point-attachment process where the joint is provided by a rivet, nail, bolt or screw [4]. The joints are depending on the tensile stresses in the attachment where the components are being hold in compression. For chem...
Dynamic shear strength of adhesive joints made of metallic and composite adherents
Materials & Design, 2010
The use of adhesive joints has gained good acceptance in the automotive and aerospace industries in recent years, particularly for joining glass fiber reinforced plastics (GFRP) to metals. Such joints will be subjected to short duration dynamic loads in service. The present study focuses on the evaluation of the shear strength of adhesive joints prepared using four different commercial adhesives at loading rates in the range of 0.6-1.2 MPa/ls. The adhesives used were Araldite 2014, Araldite 2011, Epibond 1590 and A/B Loctite 324. Joints were prepared with two different adherent combinations; aluminum-aluminum and aluminum-GFRP. The results of the study indicated that, depending on the adhesive and adherent combination, the dynamic strength was 2-4 times the static strength. Among the four adhesives, Epibond 1590 exhibited the highest rate sensitivity whereas Loctite 324 exhibited the least. Further it was also observed that the dynamic strength was not sensitive to the adherent combination whenever the failure was predominantly within the adhesive layer.
Research on strength of nanocomposite adhesively bonded composite joints
Composites Part B: Engineering, 2017
Due to their great advantages, adhesively bonded joints are frequently used in many areas like automotive, marine, space and aerospace industries. Especially findings from nanoscience and nanotechnology, which have progressed significantly in recent years, influence adhesives sciences significantly as well as other disciplines. In the present study, nanoparticles were added to the adhesive to increase the damage load of adhesively bonded single lap composite joints and tensile and bending moment damage loads of these joints were experimentally investigated. In the study, carbon fiber fabric reinforced composites (0/90) with Plain Weave were used as the adherend; rigid, tough and flexible adhesive types were used as the adhesive and 1 wt% Graphene-COOH, Carbon Nanotube-COOH and Fullerene C60 were used as the nanoparticles. As a result, based on the AA2024-T3 aluminum alloy used in a study conducted by Akpinar et al. [1], the use of carbon fiber fabric reinforced composites as the adherend considerably increases the damage load of the joint, depending on the adhesive type. Moreover, when failure loads obtained from experiments were examined, the addition of nanoparticles to the adhesive was shown to increase the tensile and four-point bending damage load of joint, depending on the adhesive and nanoparticle type.
Evaluating the Adhesive Properties of Four Types of Conventional Adhesives
Engineering and Technology Journal, 2022
The butt and single lap joint are the powerful techniques to evaluate the adhesives. • Quasi-static loads have been used effectively to find the response of adhesives. • MS Hybrid Polymers can employ in applications that have strength with flexibility. • MS Hybrid Polymers has the cohesive failure in both the normal and shear forces. The development of manufacturing technology led to the appearance of various products that need effective types of adhesives with good strength and durability in different types of joints. Accordingly, the issue is how to choose the appropriate adhesive for the specific application relying on the properties of adhesive besides, the work conditions. This work deals with the experimental testing of four types of an adhesives that have been prepared to test by the two types of joints to comprehend the behavior of adhesives then choose the most effective and optimum type. The Butt and single lap joint tests were achieved according to the ASTM standard D2095-96 and D-1002-99 respectively. The adhesives that were used were epoxy Resins, MS Hybrid Polymers, Polyvinylester, and R.T.V Silicon Rubber, also, used a steel material as adherents. The study concluded important points about these adhesives and the recommendation suggested essential points to select satiable adhesive.