Influence of nano toughened epoxies in the bonding characteristics of adhesive joints (original) (raw)
Related papers
Springer Proceedings in Energy
Epoxy composite adhesively bonded metal joints are extensively used in various industries including automobile, aerospace, oil and gas, etc. Despite their several structural advantages, the adhesively bonded composite structures suffer from peel stress concentrations due to load path eccentricity that usually act as a stimulator for cohesive and interfacial failures. Most of the adhesive and composite adhesively bonded metal joints reveal adhesive, cohesive and mixed-mode failure at the interface of adhesive and adherend interface, respectively. These failures immensely affect the whole integrity of the structure. A substantial amount of research conducted to overcome these stress concentrations by incorporating nanoparticles in epoxy adhesive for toughening of epoxy composite and achieving better wettability of adherend's surface. In the present study, a critical review has been performed to study the influence of nanoparticle type, size and concentration on performance and safety of epoxy composite adhesively bonded various metals based joints.
Composites Part B: Engineering, 2019
In this study, single lap joints were formed by adding nano-Al 2 O 3 , nano-TiO 2 and nano-Al 2 O 3 powders in various proportions to the epoxy adhesive and using the additive-free epoxy adhesive; and also the mechanical properties of the connections were experimentally investigated at 20, 25, 30, 50 and 70 mm overlap lengths under shear load. In the experimental work, DP460 epoxy adhesive was used as adhesive and AISI 304 stainless steel plate as adherent material. When the results obtained from the experiments were examined, it was revealed that the average damage load in connection with the use of nanoparticle-added adhesives increased considerably in general. As a result of the experiments, the most effective nanoparticle in increasing the failure strength of the adhesive joints with nano-Al 2 O 3 particles and the maximum failure strength increase rate was 20 mm in overlap length and 97% in 4 wt% nano-Al 2 O 3 reinforced specimens. It was also found that the nanoparticle strain was an important parameter in the tensile strength of the adhesive joints. In addition, it has been found that the addition of nanoparticles into the adhesive increases the elongation of the joints. When the adhesion surfaces of the samples were examined as in the case of plain adhesives, damage was observed as adhesion separation while nanoparticle reinforcement was observed as a mixture of adhesion and cohesion.
Journal of Adhesion Science and Technology, 2010
This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Composites Part B: Engineering, 2016
Characteristics of the lap joints of mechanically and chemically treated faying surface of dissimilar metals (Mild Steel and Aluminium) prepared by using UDM processed TiO 2-epoxy nano composite adhesive was investigated. Influence of the extent of TiO 2 nano (25e35 nm) particle reinforcement (5, 10 and 15 wt%) in the composite adhesive on the improvement of tensile lap shear strength of the adhesive joints has been studied. Effect of bond line thickness of the adhesive in lap joints of the differently treated faying surfaces of the dissimilar metals on lap shear strength of the joints has also been studied. The joints of 10 wt% TiO 2 nano-filler content epoxy adhesive shows maximum lap shear strength of the joints. Its lap shear strength was also studied at elevated temperatures in the range of 100e250 C. In order to establish the potentials of nano composite adhesive to relatively improve the properties of the joint, the lap shear strength of the adhesive joint of neat epoxy adhesive was also studied and compared.
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...
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.
Effects of bond gap thickness on the fracture of nano-toughened epoxy adhesive joints
Polymer, 2012
The current work is a combined experimental-numerical study of the fracture behaviour of a nano-toughened, structural epoxy adhesive. The mode I fracture toughness of the adhesive is measured using tapered double-cantilever beam (TDCB) tests with various bond gap thicknesses ranging from 0.25mm-2.5mm. Circumferentially deep-notched tensile specimens are independently employed to measure the cohesive strength of the adhesive as a function of constraint. The experimental TDCB test results are predicted numerically for each bond gap thickness using the Finite Volume method and a Dugdale cohesive zone model. A unique relationship between the fracture energy and the constraint level is established. The effect of bond gap thickness on the fracture behaviour of TDCB joints is hence directly attributed to the variation of the intrinsic fracture energy with constraint and thickness. Using the well known Rice and Tracey void growth model, a link is established between the voids observed in the fracture process zone, the constraint imposed by the thickness of the adhesive and the resulting fracture energy.
Performance Augmentation of Epoxy Adhesives with TiN Nanoparticles
ACS Omega
In the current study, nanoparticles (NPs) of titanium nitride (50−70 nm) in varying amounts (0−4 wt %) were uniformly suspended in an epoxy solution and then used to cast the films of nanocomposites. The same formulations were used to prepare the lap shear strength joints using stainless-steel coupons with the help of standard molds and then employing the compression molding technique. The nanocomposites films were characterized for their physical properties, thermal stability, friction performance, and scratch hardness, while the lap shear strength of joints prepared using nanocomposites as nanoadhesives was evaluated. The failed surfaces of joints were investigated using scanning electron microscopy (SEM) to understand the failure modes, that is, micro-failure mechanisms, while the cross-sectional surfaces of fractured nanocomposites were investigated using SEM to identify the distribution of NPs. The increase in the contents of NPs in the epoxy led to an almost linear increase in the selected performance properties. The highest (70%) improvement in the lap shear strength was observed with 4 wt % NPs, which was correlated with an increase in the hardness of composites.
Nano-reinforcement of Epoxy Adhesives with POSS
2005
The reinforcement of epoxy adhesives with polyhedral-Oligomeric-SilSesquioxane (POSS) was studied. Shear performance of the nano-filled adhesive was evaluated as a function of filler content using the single-strap bonded joint configuration. It is found that maximal stress and maximum shear strain both increase with the POSS loading. X-ray diffraction (XRD) analyses indicated that aggregation and crystallization of POSS occurred over the curing cycle. Dynamic mechanical analyses (DMA) showed an increased storage modulus with the addition of POSS and decreased loss modulus, hence enhanced network elasticity. The increased chain relaxation enhanced the polymer/aluminum interaction at the interface, resulting in increased interfacial strength and toughness, which was evident from the observed shift in failure mode from adhesive to cohesive for the bonded joints with increased POSS content.
International Journal of Adhesion and Adhesives, 2018
In the current study, the synergistic effect of a multi-walled carbon nanotube (MWCNT) and a nanoclay (C30B) on the mechanical, morphological and thermal behaviour of an epoxy based adhesive was investigated. The adhesive strength was investigated by conducting lap shear tests and from the test results it was observed that, Ep/1.0 C30B adhesive possessed the highest adhesive strength among all the adhesive formulations investigated and showed a 52% enhancement as compared to the pristine epoxy. Fracture analysis of different adhesive systems was investigated using scanning electron microscopy (SEM). SEM micrographs revealed that nanomaterials with different shapes and dimensions provide distinct features on the fracture surfaces due to the different energy dissipation mechanisms which they promote. The morphological variations of the epoxy based nanocomposite adhesives were investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The curing kinetics of the different nanofiller reinforced epoxy adhesives were examined using a nonisothermal differential scanning calorimetric (DSC) technique. The activation energy (E a) was calculated by applying Kissinger's method and found to be increased for the Ep/1.0 CNT/1.0 C30B adhesive system as compared to the pristine epoxy. This increment can be attributed to the physical impediment impacted by the nanomaterials on the curing reaction of the epoxy resin. The degradation kinetics of the adhesive systems were also studied using thermogravimetric analysis (TGA). The corresponding activation energies (E) of the adhesive systems obtained by Kissinger's model were found to increase with addition of nanofillers, thus indicating improved thermal stability.