Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI

Porto, Portugal

Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI

Porto, Portugal
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Monteiro J.P.R.,Polytechnic Institute of Porto | Campilho R.D.S.G.,Polytechnic Institute of Porto | Marques E.A.S.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | da Silva L.F.M.,University of Porto
Applied Adhesion Science | Year: 2015

The automotive industry is currently increasing its use of high performance structural adhesives in order to reduce vehicle weight and increase the crash resistance of automotive structures. To achieve these goals, the high performance adhesives employed in the automotive industry must not only have high mechanical strength but also large ductility, enabling them to sustain severe dynamic loads. Due to this complex behaviour, the design process necessary to engineering structures with these materials requires a complete knowledge of their mechanical properties. In this work, the mechanical properties of a structural epoxy, Sikapower® 4720, were determined. Tensile tests were performed to determine the Young’s modulus (E) and tensile strength (σf). Shear tests were performed to determine the shear modulus (G) and the shear strength (τf). Tests were also performed to assess the toughness of the adhesive. For mode I toughness determination (GIc), the double-cantilever beam (DCB) test was employed. For determination of toughness under mode II (GIIc), the end-notched flexure (ENF) test was performed. The data obtained from the DCB and ENF tests was analysed with the compliance calibration method (CCM), corrected beam theory (CBT) and compliance-based beam method (CBBM) techniques. The test results were able to fully mechanically characterize the adhesive and demonstrate that the adhesive has not only high mechanical strength but combines this with a high degree of ductility, which makes it adequate for use in the automotive industry. © 2015, Monteiro et al. All Right Reserved.


Viana G.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Costa M.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Banea M.D.,Federal University of Rio de Janeiro | da Silva L.F.M.,University of Porto
Latin American Journal of Solids and Structures | Year: 2017

Structural adhesives are increasingly being used in the aerospace and automotive industries. They allow for light weight vehicles, fuel savings and reduced emissions. However, the environmental degradation of adhesive joints is a major setback in its wide implementation. Moisture degradation of adhesive joints includes plasticization, attacking of the interface, swelling of the adhesive and consequent creation of residual stresses. This may lead to reversible and irreversible damage. In this work double cantilever beam (DCB) specimens using two different adhesives for the automotive industry were subjected to two different ageing environments. They were tested periodically until the toughness of the adhesives stabilized, which means that they were fully degraded. An association was made between the toughness of the adhesive and the amount of water that it had absorbed. This way it was possible to indirectly measure the water uptake in an adhesive joint taking into account the water uptake properties of the adhesives studied, which had been determined in another study. It was found that diffusion of water into the studied adhesive joints was faster than diffusion through the bulk adhesive alone. A model that takes into account diffusion through the interface between the adhesive and the adherends was proposed. © 2017, Brazilian Association of Computational Mechanics. All rights reserved.


Marques E.A.S.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Carbas R.J.C.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Silva F.,Robert Bosch GmbH | da Silva L.F.M.,University of Porto | And 2 more authors.
International Journal of Adhesion and Adhesives | Year: 2017

Advancements in materials technology and the use of innovative designs have led to extensive application of adhesive bonding techniques in the electric appliance industry. While the static strength of such joints is sufficient for the intended applications, long term durability remains a major concern, mainly due to creep effects. Conventional creep testing can be performed at the service temperature but it is a long test that can take decades, although it can be accelerated using high temperatures. In this work, glass-aluminium joints were studied under static and creep loads. Glass-aluminium specimens were subjected to creep testing at various temperatures. Using the time temperature superposition principle, the results of these individual creep tests were combined in a master curve that approximates the creep behaviour of the adhesive joint in a long time period. These master curves were used to guarantee a minimum service life of the joint. © 2017 Elsevier Ltd


Viana G.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Costa M.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Banea M.D.,Federal University of Rio de Janeiro | da Silva L.F.M.,University of Porto
Journal of Adhesion Science and Technology | Year: 2017

In this work, the double cantilever beam (DCB) test is analysed in order to evaluate the combined effect of temperature and moisture on the mode I fracture toughness of adhesives used in the automotive industry. Very few studies focus on the combined effect of temperature and moisture on the mechanical behaviour of adhesive joints. To the authors’ knowledge, the simultaneous effect of these conditions on the fracture toughness of adhesive joints has never been determined. Specimens using two different adhesives for the automotive industry were subjected to two different ageing environments (immersion in distilled water and under 75% of relative humidity). Once they were fully degraded, they were tested at three different temperatures (−40, 23 and 80 °C), which covers the range of temperature an adhesive for the automotive industry is required to withstand. The aim is to improve the long term mechanical behaviour prediction of adhesive joints. The DCB substrates were made of a high strength aluminium alloy to avoid plastic deformation during test. The substrates received a phosphoric acid anodisation to improve their long term adhesion to the adhesive. Results show that even though a phosphoric acid anodization was applied to the adherends, when the aged specimens were tested at room temperature and at 80 °C, they suffered interfacial rupture. At −40 °C, however, cohesive rupture was observed and the fracture toughness of the aged specimens was higher. © 2017 Informa UK Limited, trading as Taylor & Francis Group


Araujo H.A.M.,University of Porto | Machado J.J.M.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Marques E.A.S.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | da Silva L.F.M.,University of Porto
Composite Structures | Year: 2017

The automotive industry has significantly increased the use of adhesive joints in vehicle construction, which can be explained in part by the widespread adoption of composite materials and structures. The combined use of composites and bonding allows the manufacture of structures with high mechanical strength and reduced weight. However, to ensure vehicle safety, these adhesive joints must be able to sustain large impact loads, transmitting the load to the structure without damaging the joint. This work aims to study the impact behaviour of composite adhesive joints bonded with a ductile epoxy adhesive, comparing different overlap lengths. For this purpose, a characterization of the behaviour of single lap joints was performed under quasi-static and impact conditions. Dynamic tests were also performed using vibration analysis to assess the damping capabilities of the studied joints. Numerical models were developed with cohesive elements in ABAQUS® software, including both quasi-static and dynamic models. It was demonstrated that joints manufactured with this type of adhesives and substrates can exhibit excellent impact strength and damping capabilities. It was also shown that the behaviour of these joints can be successfully modelled using static and dynamic finite element analysis. © 2017 Elsevier Ltd


Machado J.J.M.,Institute Ciencia e Inovacao Em Engineering Mecanica e Engineering Industrial INEGI | Marques E.A.S.,Institute Ciencia e Inovacao Em Engineering Mecanica e Engineering Industrial INEGI | Campilho R.D.S.G.,Polytechnic Institute of Porto | da Silva L.F.M.,University of Porto
Composites Part B: Engineering | Year: 2017

Knowledge of the fracture properties of composite materials is fundamental to predict the impact behaviour of the lightweight structures currently used in the automotive industry. Although there is substantial research on mode I fracture behaviour of composites, limited information exists on mode II behaviour. This work aims to fulfil this gap, presenting experimental data regarding the influence of temperature and strain rate on the fracture energy in mode II, GIIC, of composite plates. Significant influence of the strain rate and temperature on GIIC of the composite materials was found. Higher strain rates led to a decrease of GIIC up to 17%. An increase of temperature corresponded to an increase of GIIC up to 15% and a decrease of temperature originated a decrease of GIIC up to 7%. © 2017 Elsevier Ltd


Banea M.D.,Federal University of Rio de Janeiro | da Silva L.F.M.,University of Porto | Carbas R.J.C.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | de Barros S.,Federal University of Rio de Janeiro
Journal of Adhesion | Year: 2016

In this work an innovative technique for multi-material adhesive joints debonding by combining the inductive heating method and the use of thermally expandable particles (TEPs) is presented. First, single lap joints (SLJs) using various combinations of adherends (high-strength steel (HS), aluminum (Al), and carbon fiber reinforced plastics (CFRP)) were fabricated and tested to assess the influence of TEP content on the lap-shear strength of the joints. Further, the ability of the TEP-modified joints to support temperature-controlled debonding was evaluated. It was showed that the control of debonding process by temperature is possible. The temperature needed for debonding is a function of TEP content and can be lowered by increasing the TEP content. Relatively similar debonding temperatures were found for multi-material/dissimilar joints debonding compared with similar joints, but more induction heating power is generally necessary to disassemble multi-material adhesive joints. © 2016 Taylor & Francis


Viana G.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Costa M.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Banea M.D.,Federal University of Rio de Janeiro | Da Silva L.F.M.,University of Porto
Journal of Adhesion | Year: 2016

Structural adhesives are increasingly being used in the aerospace and automotive industries. They allow for light weight vehicles, fuel savings, and reduced emissions. However, the environmental degradation of adhesive joints is a major setback in its wide implementation. Moisture degradation of adhesive joints includes plasticization, attacking of the interface, swelling of the adhesive and consequent creation of residual stresses. This may lead to reversible and irreversible damage. The main factors affecting the strength of adhesive joints under high and low temperatures are the degradation of the adhesive mechanical properties and the creation of residual stresses induced by different coefficients of thermal expansion (between the adhesive and the adherends). The effect of the combined effect of moisture and temperature is not yet fully understood. The aim of this study is to shed light on this subject. In this work bulk water absorption tests were conducted at different moisture conditions in order to assess the diffusion coefficient, maximum water uptake, and glass transition temperature. Aged and unaged small dogbone tensile specimens were tested under different temperature conditions. The glass transition temperature of the adhesives as a function of the water uptake was assessed. The aim is to determine the evolution of the properties of two epoxy adhesives as a function of two variables (environmental temperature and moisture). © 2016 Taylor & Francis


Silva M.R.G.,University of Porto | Marques E.A.S.,University of Porto | da Silva L.F.M.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI
Latin American Journal of Solids and Structures | Year: 2016

The automotive industry is increasingly using adhesive joints bonding advanced lightweight materials to reduce vehicle weight. Strength under impact loadings is a major concern for this application and mixed adhesive joints can effectively improve the joints by combining stiffness and flexibility on the same overlap. This work introduces and studies several configurations for static and impact tests of mixed adhesive joints with four adhesives in different combinations. The main purpose of this work is the development of a strong adhesive joint using a mixed adhesive layer and perform a series of mechanical to study its mechanical behaviour. It is concluded that the use of the mixed adhesive technique improves both static and impact strength by introducing flexibility to the joint which subsequently allows more energy absorption when introduced in crash resistant structures. © 2016, Latin American Journal of Solids and Structures. All rights reserved.


Marques E.A.S.,Institute Ciencia e Inovacao em Engineering Mecanica e Engineering Industrial INEGI | Campilho R.D.S.G.,Polytechnic Institute of Porto | Da Silva L.F.M.,University of Porto
Journal of Adhesion Science and Technology | Year: 2016

The use of adhesives for high-performance structural applications has significantly increased in the last decades. However, the use of adhesive joints in adverse environmental conditions is still limited due to the reduced capability of adhesives to withstand large thermal gradients. Dual adhesive joints, which contain two adhesives with remarkably different mechanical behaviours, are a technique suitable for being used in extreme temperatures. The object of this study is a ceramic-metal joint, representative of the thermal protection systems of some aerospace vehicles. In this paper, several joint-mixed joint geometries are presented, studied with recourse to finite element analysis. In a first phase, the three-dimensional finite element models and the material properties are validated against experimental data. In a second phase, the model geometry is modified, with the aim of understanding the effect of several changes in the joints mechanical behaviour and comparing the merits of each geometry. The models presented good agreement was found between experimental and numerical data and the alternative geometries allowed the introduction of additional flexibility on the joint but at the cost of lower failure load. © 2015 Taylor & Francis.

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