NON-DESTRUCTIVE EVALUATION OF MECHANICAL DAMAGE OF ADHESIVES USING MAGNETO-ELECTRIC NANOPARTICLES

2021 ◽  
Author(s):  
GONZALO SEISDEDOS ◽  
BRIAN HERNANDEZ ◽  
JULIETTE DUBON ◽  
MARIANA ONTIVEROS ◽  
BENJAMIN BOESL ◽  
...  
Keyword(s):  
Adhesive Joint ◽  
Adhesive Bonding ◽  
Mechanical Damage ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Adhesive Joints ◽  
Adhesive Bonds ◽  
Magnetic Signatures ◽  
Looper System ◽  
Lock In

Adhesive bonding has been shown to successfully address some of the main problems with traditional fasteners, such as the reduction of the overall weight and a more uniformly distributed stress state. However, due to the unpredictability of failure of adhesive bonds, their use is not widely accepted in the aerospace industry. Unlike traditional fastening methods, it is difficult to inspect the health of an adhesive joint once it has been cured. For adhesive bonding to be widely accepted and implemented, there must be a better understanding of the fracture mechanism of the adhesive joints, as well as a way to monitor the health of the bonds nondestructively. Therefore, in-field structural health monitoring is an important tool to ensure optimal condition of the bond is present during its lifetime. This project focuses on the advancement of a non-invasive field instrument for evaluation of the health of the adhesive joints. The tool developed is based on a B-H looper system where coils are arranged into a noise-cancellation configuration to measure the magnetic susceptibility of the samples with a lock-in amplifier. The B-H looper system can evaluate the state of damage in an adhesive bond by detecting changes in surface charge density at the molecular level of an epoxy-based adhesive doped with magneto-electric nanoparticles (MENs). Epoxy-based adhesive samples were doped with MENs and then scanned using the B-H looper system. To evaluate the health of the adhesive joint, microindentation and tensile tests were performed on MENs-doped adhesive samples to understand the relationship between mechanical damage and magnetic signal. Correlations between magnetic signatures and mechanical damage were minimally observed, thus future studies will focus on refining the procedure and damaging methodology.

Adhesive Bonding

2020 ◽  
pp. 1-25
Keyword(s):  
Adhesive Bonding ◽  
Adhesive Bond ◽  
Bonding Process ◽  
Manufacturing Processes ◽  
Adhesive Bonds ◽  
Different Types ◽  
Bonding Technology ◽  
Basic Concepts

This chapter presents the application of adhesive bonding technology with a long tradition of use in manufacturing processes. It has an established position among a number of different ways of permanently joining elements together. This work offers a list of many advantages of this technology, alongside the difficulties and limitations in the use of adhesive bonds. The basic concepts of adhesives and their components are described, and the terms related to the bonding process are presented. Attention was paid to the great variety of adhesives and many different criteria of their division and selection to a particular technological situation. In the following chapter, examples of the application of different types of adhesives with regard to using materials and constructions can be found as well as methods and requirements for the preparation of the finished adhesive. Mechanisms of the formation of an adhesive bond are characterized, and various constructions of adhesive bonds that are necessary to form a durable bond of elements are presented.

scholarly journals Adhesive Bond Imaging by Noncontact Measurements With Single-Sided Access

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Shogo Nakao ◽  
Takahiro Hayashi
Keyword(s):  
Flat Plate ◽  
Adhesive Bonding ◽  
Imaging Technique ◽  
Laser Doppler Vibrometer ◽  
Adhesive Bond ◽  
Scanning Laser ◽  
Laser Source ◽  
Adhesive Bonds ◽  
Plate Structure ◽  
Noncontact Measurements

Adhesive bonding, an effective joining technique for platelike structures in aircraft and automobiles, requires postbond inspection preferably with noncontact and single-sided access. The present study discusses the application of an imaging technique with a scanning laser source (SLS) to evaluate adhesive bonds in a platelike structure. When a laser Doppler vibrometer (LDV) is used as a receiver, the SLS technique realizes noncontact measurements with single-sided access. The imaging experiments that used narrowband burst waves and broadband chirp waves indicated that the imaging technique is appropriately applied to adhesive bonds and that the use of broadband chirp waves provides clearer images and reduces spurious images due to resonance. Furthermore, images of adhesive bonds were clearly obtained for a complex plate structure that consisted of a top-hat section and a flat plate, and this demonstrates that the imaging technique can be widely applied to evaluate various adhesive bonds.

Adhesive bond strength of end grain joints in softwood with varying density

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Jürgen Follrich ◽  
Alfred Teischinger ◽  
Wolfgang Gindl ◽  
Ulrich Müller
Keyword(s):  
Bond Strength ◽  
Compression Wood ◽  
Adhesive Bonding ◽  
Adhesive Bond ◽  
Adhesive Joints ◽  
Mechanical Interlocking ◽  
Cross Sectional ◽  
Wall Area ◽  
Spruce Wood ◽  
Adhesive Bond Strength

Abstract Norway spruce wood specimens covering a wide density range, including density samples between 300 kg m-3 (low density wood) and 750 kg m-3 (high-density compression wood), were joined at end grain surfaces and tested in tension perpendicular to the bonded surface to estimate the effect of mechanical interlocking on the adhesive bond strength. It was hypothesised that the higher the density of the specimens the lower will be the mechanical interlocking of the adhesive joints due to a reduced penetration of the adhesive into the cell cavities. An increase of tensile strength was observed with increasing density. These results demonstrate that in the specific case investigated here the cross-sectional cell wall area available for adhesive bonding, which correlates with density, is probably more important than mechanical interlocking.

Loading Behavior Investigation of Composite Single Lap Adhesive Joints

2013 ◽  
Vol 387 ◽  
pp. 202-207
Author(s):  
Hai Xiao Hu ◽  
Yun Dong Ji ◽  
Ai Qing Ni ◽  
Ji Hui Wang
Keyword(s):  
Shear Stress ◽  
Adhesive Bonding ◽  
Nonlinear Behavior ◽  
Adhesive Bond ◽  
Adhesive Joints ◽  
Surface Strain ◽  
Strain Gages ◽  
Composite Joint ◽  
Fbg Sensors ◽  
Peel Stress

Adhesive bonding as a promising join technique for composites is not widely used for the absence of absolutely understanding of loading behavior. In this paper both electric-strain gages and FBG sensors were employed to get the internal and surface strain of adhesive joint. In the experiment, nonlinear behavior is observed. Then the test data were compared with FEM results. It is showed that they meet each other well, FEM could get the stress distribution in adhesive bond composite joint, and both biggest peel stress and shear stress are appear at the end of adhesive.

Detection of failures of adhesively bonded joints using the acoustic emission method

Holzforschung ◽  
2005 ◽  
Vol 59 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Cezary Gozdecki ◽  
Jerzy Smardzewski
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Adhesive Bond ◽  
Acoustic Signals ◽  
Wood Adhesive ◽  
Adhesive Joints ◽  
Structural Defects ◽  
Adhesive Bonds ◽  
Tangential Stresses ◽  
Characteristic Points

Abstract Wooden glued constructions require touch-free monitoring of destructive processes, especially in adhesive bonds that are most exposed to failure. The objective of the investigations was to describe failure processes in the adhesive bond of wood joints, in particular to determine their initiation, propagation, and destruction. The acoustic emission (AE) method was employed as the carrier of information about changes occurring in glued joints, whereas the numerical method was applied to determine values of distribution of tangential stresses generated in adhesive bonds. The acoustic phenomena examined were described using the AE cumulative counts. The authors analysed acoustic signals generated in loaded wooden and plastic overlap samples glued together using polyethyl methacrylate glue as well as in solid samples. On the basis of the acoustic emissions obtained, it was possible to establish characteristic places and stages of escalating structural defects generated from bonds of adhesive joints. This was utilised later on, in conjunction with results of numerical calculations, to determine correlations occurring between the AE cumulative counts and generated tangential stresses. Dependencies established in this way were used to determine characteristic points during the propagation of destructive phenomena of wood adhesive joints. The results obtained proved that it was possible to predict the development of the destruction of wood adhesive joints on the basis of observations of the increasing AE cumulative counts of acoustic signals in combination with tangential stresses determined using the finite elements method.

scholarly journals Apparent Young’s Modulus of the Adhesive in Numerical Modeling of Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 328
Author(s):  
Kamil Anasiewicz ◽  
Józef Kuczmaszewski
Keyword(s):  
Numerical Model ◽  
Young’S Modulus ◽  
Adhesive Joint ◽  
Young's Modulus ◽  
Precise Determination ◽  
Adhesive Joints ◽  
Experimental Conditions ◽  
Element Simulation ◽  
Joint Material

This article is an evaluation of the phenomena occurring in adhesive joints during curing and their consequences. Considering changes in the values of Young’s modulus distributed along the joint thickness, and potential changes in adhesive strength in the cured state, the use of a numerical model may make it possible to improve finite element simulation effects and bring their results closer to experimental data. The results of a tensile test of a double overlap adhesive joint sample, performed using an extensometer, are presented. This test allowed for the precise determination of the shear modulus G of the cured adhesive under experimental conditions. Then, on the basis of the research carried out so far, a numerical model was built, taking the differences observed in the properties of the joint material into account. The stress distribution in a three-zone adhesive joint was analyzed in comparison to the standard numerical model in which the adhesive in the joint was treated as isotropic. It is proposed that a joint model with three-zones, differing in the Young’s modulus values, is more accurate for mapping the experimental results.

Adhesives in engineering

1997 ◽  
Vol 211 (5) ◽  
pp. 307-335 ◽  
Author(s):  
A J Kinloch
Keyword(s):  
Molecular Weight ◽  
Fracture Mechanics ◽  
Service Life ◽  
Adhesive Joint ◽  
Adhesive Joints ◽  
Liquid Form ◽  
Engineering Applications ◽  
Advantages And Disadvantages ◽  
Load Carrying ◽  
Made In

When considering methods for joining materials, there are many advantages that engineering adhesives can offer, compared to the more traditional methods of joining such as bolting, brazing, welding, mechanical fasteners, etc. The advantages and disadvantages of using engineering adhesives are discussed and it is shown that it is possible to identify three distinct stages in the formation of an adhesive joint. Firstly, the adhesive initially has to be in a ‘liquid’ form so that it can readily spread over and make intimate molecular contact with the substrates. Secondly, in order for the joint to bear the loads that will be applied to it during its service life, the ‘liquid’ adhesive must now harden. In the case of adhesives used in engineering applications, the adhesive is often initially in the form of a ‘liquid’ monomer which polymerizes to give a high molecular weight polymeric adhesive. Thirdly, it must be appreciated that the load-carrying ability of the joint, and how long it will actually last, are affected by: (a) the design of the joint, (b) the manner in which loads are applied to it and (c) the environment that the joint encounters during its service life. Thus, to understand the science involved and to succeed in further developing the technology, the skills and knowledge from many different disciplines are required. Indeed, the input from surface chemists, polymer chemists and physicists, materials engineers and mechanical engineers are needed. Hence, the science and technology of adhesion and adhesives is a truly multidisciplined subject. These different disciplines have been brought together by developing a fracture mechanics approach to the failure of adhesive joints. The advances that have been made in applying the concepts of fracture mechanics to adhesive joints have enabled a better understanding of the fundamental aspects of adhesion and the more rapid extension of adhesives technology into advanced engineering applications.

Adhesive bond strength between orthodontic resin and acrylic surfaces

2020 ◽  
pp. 1-5
Author(s):  
Evelyn Guadalupe Torres-Capetillo ◽  
Guadalupe Rosalía Capetillo-Hernández ◽  
Laura Roesch-Ramos ◽  
Flora Moreno-Marín
Keyword(s):  
Bond Strength ◽  
Adhesive Bonding ◽  
Statistical Processing ◽  
Adhesive Bond ◽  
Diamond Bur ◽  
Fine Diamond ◽  
Adhesive Bond Strength ◽  
Application Protocols ◽  
Made In

The use of orthodontic treatments in patients with temporary prostheses has been increasing, the purpose of this in vitro research is to measure the adhesive bond strength between orthodontic resin and acrylic surfaces by applying different procedures. Objective. To compare the adhesive bonding strength between orthodontic resin and acrylic surfaces under different application protocols. Methodology. Transversal, experimental, prospective study. In vitro with acrylic provisions, was carried out in the laboratory of the Faculty of Dentistry of the Universidad Veracruzana region of Veracruz. In the period of February-June of the year 2019. The sample was conformed by two control groups of specimens and four experimental ones, each group conformed by 20 specimens, in total 120 provisional ones were made in acrylic Nic Tone of quick self-cure. The tests performed by the ULTRATESTER machine were expressed in MPa. Later, the data obtained were processed in Excel tables (version) for statistical processing in SPSS version 24. Contribution. When comparing the pre-cutting protocol of acrylic surfaces with fine diamond bur and the protocol without pre-cutting, no statistically significant differences were found, therefore, this step could be omitted in clinical practice.

scholarly journals Durability of flax/bio-based epoxy composites intended for structural strengthening

2018 ◽  
Vol 199 ◽  
pp. 07014
Author(s):  
Karim Benzarti ◽  
Robert Chlela ◽  
Wendlamita Zombré ◽  
Marc Quiertant ◽  
Laurence Curtil
Keyword(s):  
Natural Fibers ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Accelerated Ageing ◽  
Scanning Calorimetry ◽  
Major Drawback ◽  
Sorption Behaviour ◽  
Frp Composites ◽  
Externally Bonded ◽  
Interlaminar Shear

Environmentally friendly FRP composites, made of natural fibres and bio-based polymer matrices, may be used as externally bonded reinforcement for civil structures or buildings subjected to moderate outdoor conditions, in replacement of traditional carbon/epoxy systems. However, a major drawback of natural fibers is their sensitivity to moisture, which can affect both the mechanical properties of FRP composites and their adhesive bond with concrete. This research, funded by the French National Research Agency (ANR Project MICRO), aims at studying the influence of hygrothermal ageing on the performances of “green composites” manufactured by hand lay-up process using unidirectional flax fabrics and a bio-based epoxy matrix. The test program consists in subjecting FRP laminates and FRP strengthened concrete slabs to accelerated ageing conditions under various combinations of temperature and humidity. Aged laminates are then periodically characterized by tensile tests and interlaminar shear tests, while the bond properties of concrete/composite assemblies are assessed by pull-off tests. This paper presents the first results of this ongoing program which is scheduled over a period of 2 years. Results are discussed in the light of complementary investigations (water sorption behaviour, microscopic observations and evaluation of the glass transition temperature by differential scanning calorimetry – DSC) in order to relate observed performance evolutions to actual microstructural changes or damage processes taking place in the material.

Fracture Mechanics of Adhesive Bonds

1974 ◽  
Vol 47 (1) ◽  
pp. 202-212 ◽  
Author(s):  
A. N. Gent
Keyword(s):  
Adhesive Joint ◽  
Unit Area ◽  
Energy Requirement ◽  
Critical Energy ◽  
Thermal Contraction ◽  
Adhesive Bonds ◽  
Adhesive Layers ◽  
Modes Of Failure ◽  
Shear Rupture ◽  
Set Up

Abstract A survey is given of the mechanics of rupture of a simple adhesive joint, comprising two relatively rigid adhering members joined by a layer of a deformable adhesive. Several different modes of failure are treated in terms of a critical energy requirement for growth by unit area of a pre-existing interfacial flaw or debond. They are: (i) Tensile rupture of joints with thick or thin adhesive layers, (ii) Shear rupture, (iii) Separation by stripping apart stiff or flexible adherends, i.e. cleavage. In addition, the stresses set up in joints by shrinkage of the adhesive, for example due to differential thermal contraction, are evaluated. Attention is drawn to probable sites and conditions for failure.

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