Negative electronic word-of-mouth (NWOM): How to avoid and respond to negative online feedback

The following thesis has two main goals: taking into account extensive research of valuable literature, whose study comprises a series of variables related to both the antecedents/determinants of negative word-of-mouth, and the different strategies that are used when responding to these messages. In addition, its methodology confronts the participants with different combinations of such responding approaches, which aims to showcase whether there is a clear best practice for these situations. Moreover, the primary data collected within the methodology – an online questionnaire – directly addressed the significance of the variables identified in the literature for the antecedents and the negative word-of-mouth response strategies. The conclusions reached are of important value for communication managers by highlighting some of the feelings that lead customers to write negative online comments and the best approaches to answer them. In fact, the major findings of the study reveal that most of the concepts showcased in the literature are confirmed in this methodology and reveal some of the best practices in responding to negative word-of-mouth.A seguinte tese tem dois principais objetivos: baseado num processo de investigação extensivo de literatura relevante, este estudo compreende um conjunto de variáveis relativas tanto aos antecedentes/determinantes de word-of-mouth negativo, como às diferentes estratégias de resposta a estas mensagens. Para além disso, a metodologia desta dissertação confronta os seus participantes com diferentes abordagens de resposta, com o objetivo de demonstrar quais as melhores práticas neste tipo de situações. Ademais, os dados primários da metodologia – um questionário online – abordam diretamente a significância das variáveis identificadas na literatura para os antecedentes e para os diferentes tipos de resposta a mensagens de word-of-mouth negativo. As conclusões aferidas são de valor considerável para gestores de comunicação por salientarem alguns dos sentimentos que levam os clientes a escrever comentários negativos e as melhores abordagens de resposta. Efetivamente, as principais ilações do estudo revelam que a grande maioria dos conceitos referidos na literatura se confirmam nesta metodologia e revelam práticas eficazes de responder a mensagens de word-of-mouth negativo

Experimental and numerical study on GFRP-GLASS adhesively bonded joints

This paper presents experimental and numerical investigations on adhesively bonded double lap joints composed of glass and GFRP pultruded profiles. The experimental programme comprised the study of the effects of using three different adhesives (with varying stiffness) on the bond behaviour of the joints in terms of stiffness, strength, ultimate displace-ment and axial strain development along the GFRP-adhesive interface. In the numerical study, 2D finite element models of the joints were developed in order to simulate the bond behaviour observed in the experiments. Interface elements with either linear or non-linear bond-slip consti-tutive relations were used to simulate the adhesive layers and their shear properties. The numer-ical models were validated by comparing experimental and numerical load vs. relative dis-placement curves and their accuracy was further verified through comparison of the load vs. axial strain distributions along the interfaces.(undefined

Experimental investigations on continuous glass-GFRP beams: preliminary nonlinear numerical modelling

This paper describes results of experimental and numerical investigations about the structural behaviour of composite beams made of annealed glass panes and GFRP pultruded profiles. A brief description of flexural tests previously carried out on simply supported glass and glass-GFRP composite beams is first presented. Then, results of flexural tests on two-span glass-GFRP composite beams, bonded with three different structural adhesives, are described in detail. Finally, a preliminary numerical study of the glass-GFRP composite simply supported beams is presented. In this study, two-dimensional finite element models were developed in order to simulate and analyse the serviceability and post-cracking behaviour of those beams. Experimental and numerical results presented in this paper prove the advantages and technical viability of glass-GFRP composite beams

Numerical simulation of the flexural behaviour of composite glass-GFRP beams using smeared crack models

This paper presents a numerical study about the flexural behaviour of rectangular composite glass-GFRP beams, comprising annealed glass and GFRP pultruded profiles bonded with two different adhesives: (soft) polyurethane and (stiff) epoxy. The main objectives of this study were: (i) to fully characterize the non-linear behaviour of glass using the smeared crack approach; and (ii) to assess the applicability of different options to simulate adhesively bonded glass-GFRP joints. An extensive parametric study was developed to evaluate the influence of five parameters on the glass post-cracking non-linear behaviour: (i) glass fracture energy, Gf, (ii) crack band width, h, (iii) glass tensile strength, fg,t, (iv) shape of the tension-softening diagram, and (v) shear retention factor, β. The wide range of the joints’ shear stiffness was simulated by either (i) assuming a perfect bond between glass and GFRP (i.e., neglecting the presence of the adhesive), or (ii) explicitly considering the adhesive, by means of using (ii.1) plane stress elements, or (ii.2) interface elements. For the beams analysed in this paper, the following material model for glass provided a good agreement with experimental results: Gf in the range of 3 to 300 N/m, h equal to the square root of the finite element area, fg,t = 50 MPa, linear softening diagram and β according to a power law. It was also shown that the hypothesis of perfect bond at the GFRP-glass interfaces allows for an accurate simulation of joints with high levels of interaction (epoxy), while calibrated interface elements are needed for joints with low level of interaction (polyurethane).The authors wish to acknowledge FCT, ICIST/CERIS and ISISE for funding the research, and companies SIKA, Guardian and ALTO for supplying the adhesives, the glass panes and the GFRP pultruded profiles used in the experiments. The first author also wishes to thank FCT for the financial support through his PhD scholarship SFRH/BD/80234/2011

Numerical simulation of transparent glass-GFRP composite beams using smeared crack models

This paper describes results of experimental and numerical investigations about the structural behaviour of composite beams made of annealed glass panes and GFRP pultruded profiles. A brief description of flexural tests previously carried out on glass and glass-GFRP composite beams is first presented. The second part of this paper describes the numerical simulation of a rectangular glass-GFRP composite beam. Two-dimensional finite element (FE) models of the composite beam were developed in order to simulate and analyse their serviceability behaviour (prior to glass breakage) as well as their post-cracking behaviour until the failure. To this end, a multi-fixed smeared crack model was used, and the effects of the following parameters were evaluated: (i) fracture energy of glass and (ii) shear retention factor. Experimental and numerical results are compared regarding the cracking load and post-cracking behaviour, namely in terms of crack pattern and load-deflection response.(undefined

Numerical simulation of GFRP-reinforced glass structural elements under monotonic loading

Several reinforcing strategies have recently been developed to overcome glass brittleness and numerical simulations are essential to investigate the structural behaviour of such hybrid systems. Based on previous experimental results from monotonic quasi-static tests, this paper presents a numerical study about the flexural behaviour of glass beams reinforced with glass fibre reinforced polymer (GFRP) laminates bonded with two different adhesives: polyurethane and epoxy. The main objective of this study is to evaluate the efficiency of different constitutive models to simulate the non-linear behaviour of glass, considering the following factors: initial stiffness, cracking load, post-cracking stiffness, crack pattern and progressive failure. The glass is simulated using smeared crack (SCM) and damaged plasticity (DPM) models with static and dynamic numerical approaches. Particular attention is paid to the influence of the several parameters that influence the structural behaviour of glass (e.g. threshold angle), as well as to the interfaces between all the materials involved (e.g. thickness of the adhesive layer). In relation to static numerical approaches, dynamic numerical approaches require more computational effort and their dynamic effects may influence the structural responses obtained; however, they also show to be able to capture all the stages of cracking in greater detail, because stability during cracking formation is guaranteed even at smaller loading stages. Since DPM models do not allow considering a maximum absolute damage factor of 1.0, the smeared crack models simulate better the non-linear behaviour of glass.The first and third authors wish also to acknowledge the grants SFRH/BD/122428/2016 and SFRH/BSAB/150266/2019, respectively, provided by Fundação para a Ciência e a Tecnologia, IP (FCT), financed by European Social Fund and by national funds through the FCT/MCTES

Numerical analyses of the effect of SG-interlayer shear stiffness on the structural performance of reinforced glass beams

This paper focuses on the numerical modelling of SentryGlas-laminated reinforced glass beams. In these beams, which have been experimentally investigated in preceding research, a stainless steel reinforcement section is laminated at the inner recessed edge of a triple-layer glass beam by means of SentryGlas (SG) interlayer sheets. The current contribution numerically investigates the effect of the SG-interlayer shear stiffness on the overall structural response of the beams. This is done by means of a 3D finite element model in which the individual glass layers, the SG-interlayers and the reinforcement are incorporated. In the model, the glass parts are allowed to crack, but all other parts are assumed linear elastic throughout the analyses. By changing the shear modulus of the SG-interlayer in multiple analyses, its contribution to the overall structural performance of the beams – especially at the post-breakage stage – is investigated. From the results of the analyses it is observed that the residual load-bearing capacity, i.e. the load-bearing capacity after glass fracture, increases with an increasing shear modulus of the SG-interlayer. Furthermore, the load-displacement response from the numerical model is predicting experimental observations very well. However, the crack pattern resulting from the numerical model is not matching the experimental observations. Further studies are thus needed to fully understand the mechanisms involved in the structural behaviour of SGlaminated reinforced glass beams