Search results

The present study deals with the numerical modeling of the low-velocity impact damage of laminated composites which have increasingly important applications in aerospace primary structures. Such damage, generated by various sources during ground handling, substantially reduces the mechanical residual performance and the safe-service life. The purpose of this paper is to present and validate a computationally efficient approach in order to explore the effect of critical parameters on the impact damage characteristics.

Numerical modeling is considered as one of the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intralaminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS® programme.

The employed modeling approach is validated using corresponding numerical data found in the literature and the presented results show a reasonable correlation to the available literature data. It is demonstrated that the current model can be used to capture the force-time response as well as damage parameter maps showing the intralaminar damage evolution for different impact cases with respect to the physical boundary conditions and a range of impact energies.

Low-velocity impact damage of laminated composites is still not well understood due to the complexity and non-linearity of the damage zone. The presented model is used to predict the force-time response which is considered as one of the most important parameters influencing the structural integrity. Furthermore, it is used for capturing the damage shape evolution, exhibiting a high degree of capability as a damage assessment computational tool.

Drawing on the service-dominant logic and the institutional theory, this paper aims to explore the value-creating mechanisms of branding in the destination context and the brand co-creation process at and between different levels of a service ecosystem.

An exploratory research design was used to generate qualitative data from 18 in-depth interviews with important stakeholders and investigate how and why brand co-creation is fostered in the service ecosystem.

The study proposes a stepwise process of strategic imperatives for brand co-creation in the destination context. It presents the multi-directional flows of the brand meaning across levels of the tourism ecosystem and thereby interprets stakeholders’ efforts to co-create sustainable brands that gain prominence in the global tourism arena.

Future research might validate the framework in a quantitative research setting. The extended analysis of the value-creating ecosystem could investigate the role of institutions and brand value propositions across levels.

Acknowledging their limited control over the brand co-creation process, tourism practitioners are offered step-by-step guidance to help shape a destination brand that may retain relevance in the tourists’ minds. Critical insights are provided into resource sharing between actors and subsequent responsibilities for a sustainable destination branding strategy.

The paper considers the significance of the various levels in the ecosystem and the underlying mechanisms of brand co-creation in a somewhat neglected branding domain.

The purpose of this paper is to implement a micromechanical hybrid finite element approach in order to investigate the stress transfer behavior of composites reinforced with hexagonal boron nitride (h-BN) nanosheets.

For the analysis of the problem, a three-dimensional representative volume element, consisting of three phases, has been used. The reinforcement is modeled discretely using spring elements of specific stiffness while the matrix material is modeled as a continuum medium using solid finite elements. The third phase, the intermediate one, known as the interface, has been simulated by appropriate stiffness variations which define a heterogeneous region affecting the stress transfer characteristics of the nanocomposite.

The results show a good agreement with corresponding ones from the literature and also the effect of a number of factors is indicated in stress transfer efficiency.

This is the first time that such a modeling is employed in the stress transfer examination of h-BN nanocomposites.

The purpose of this paper is to simulate and investigate the thermomechanical properties of graphene-reinforced nanocomposites.

The analysis proposed consists of two stages. In the first stage, the temperature-dependent mechanical properties of graphene are estimated while in the second stage, using the previously derived properties, the temperature-dependent properties of graphene-reinforced PMMA nanocomposites are investigated. In the first stage of the analysis, graphene is modeled discretely using molecular mechanics theory where the interatomic interactions are simulated by spring elements of temperature-dependent stiffness. The graphene sheets are composed of either one or more (up to five) monolayer graphene sheets connected via van der Waals interactions. However, in the second analysis stage, graphene is modeled equivalently as continuum medium and is positioned between two layers of PMMA. Also, the interphase between two materials is modeled as a medium with mechanical properties defined and bounded by the two materials.

The mechanical properties including Young’s modulus, shear modulus and Poisson’s ratio due to temperature changes are estimated. The numerical results show that the temperature rise and the multiplicity of graphene layers considered lead to a decrease of the mechanical properties.

The present analysis proposes an easy and accurate method for the estimation of the temperature-dependent mechanical properties of graphene-reinforced nanocomposites.

A computational structural mechanics approach, based on the exclusive use of standard bar elements is utilized in order to investigate the elastic stability of single-walled carbon nanotubes (SWCNTs) with atom vacancy defects under axial compressive loads. The paper aims to discuss this issue.

The proposed model uses three dimensional, two nodded, linear truss finite elements of three degrees of freedom per node to represent the force field appearing between carbon atoms due to the basic interatomic interactions.

Numerical results concerning the critical forces which cause instability of pristine nanotubes are compared with corresponding data given in the open literature in the effort to demonstrate the good accuracy of the method. Then, it is assumed that SWCNTs present-specific structural defects defined by their length, width, orientation and longitudinal position. The influence of these four geometric parameters of the imperfections considered on the stability of SWCNTs is investigated in detail and essential conclusions are revealed.

To the authors’ best knowledge, is the first time that the specific method is introduced for the prediction of buckling behavior of defective SWCNTs. The structural defect here is considered as atoms vacancy that forms a like-crack defect having a specific length, width, orientation and position along the nanotube length.

The paper is devoted to presenting a systematic investigation on the mechanical model and nonlinear dynamic characteristics of spur gear system with and without input shaft crack.

Considering the backlash, load-distribution, time-varying meshing stiffness and sliding friction, the modelling of a 5DOF gear system is proposed. Likewise, stiffness and damping models under elastohydrodynamic lubrication are developed, and sliding friction between gear pair is also outlined. In particular, a cracked input shaft which affects the support stiffness is presented, and breathing crack in keyway is adopted. On this basis, the dynamic responses of a gear system with and without input shaft crack are examined using numerical method, and some classical response diagrams are given, illustrating the effect of the important parameters on the gear system.

Dynamic simulation demonstrates that there exist periodic, quasi-periodic and chaotic motions in the gear system, and rational speed of the gear pair has noteworthy effects on vibration characteristic. Besides, comparison between healthy and cracked condition of input shaft indicates that occurring of crack convert periodic motion to quasi-periodic or chaotic motion.

The results give an understanding of the operating conditions under which undesirable dynamic behavior occurs, and provide some useful information to design and diagnose such gear system with crack fault.

The purpose of this paper is to examine the potential of single-walled carbon nanotubes as mass sensors by developing analytical expressions and then comparing the outcome with structural mechanics corresponding predictions.

The carbon nanotube (CNT) resonators are assumed to be either single or double clamped. Analytical formulas capable of describing the vibrational behavior of such CNT-based nanoresonators with an attached mass at nanotube tip or various intermediate positions are developed by combining the Euler–Bernoulli theory and Krylov–Duncan functions.

The validity and the accuracy of these formulas are examined for a wide range of cases via comparisons with corresponding results arisen by spring- or beam-based structural mechanics predictions. Both structural mechanics approaches utilize three-dimensional nanoscale elements formulated according to the molecular theory. The results indicate that the new sensor equations may be utilized for the estimation of vibration response of CNT-based mass sensors with reasonable accuracy.

Simple analytical formulas are proved to approximate the mass sensing ability of CNTs adequately, the fact that may significantly contribute in the effort of developing new sensor devices.

This paper aims to examine the dynamic behaviours of a three-dimensional (3D) rod-fastening rotor bearing system (RFBS) with a crack in a fastening rod.

Based on the 3D finite element method model and stress analysis of a cracked RFBS, a 3D dynamic model of the RFBS with a crack in a fastening rod is established with considering the initial bending and stress redistribution caused by the crack. A combined numerical simulation technology is used to investigate the dynamic behaviours of the system.

The distribution of contact stress between the two disks will be not uniform, and the initial bending of the system will occur due to the presence of a crack. This will lead to the change of system stiffness and the dynamic behaviours such as vibration amplitude, and motion orbits will change significantly.

A 3D finite element method dynamic model is proposed for the study of dynamic characteristics of complex combined rotor bearing system with cracks.

It is helpful and significant to master the dynamic behaviours of cracked RFBS. It is helpful to detect the presence of a crack of the rotor bearing system.

Some of the losses caused by crack failure may be reduced.

The proposed 3D method can provide a useful reference for the study of dynamic characteristics of complex combined rotor bearing system with cracks.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0189

Though customer experience (CX) is identified as a key research priority, empirically led insight with tourism consumers' resulting emotional attachment (EA) and customer loyalty (CL) remains scarce, particularly during the COVID-19 crisis. Adopting service-dominant logic, this study develops a model that investigates the impact of customer engagement (CE) and customer co-creation (CC) on CX, which consequently effects EA and CL during the COVID-19 crisis in the tourism industry. First, our results suggest that CE and CC positively affect tourism CX. Second, results revealed the CX's significant positive effect on EA and CL. Third, findings confirmed the CE's and CC's indirect impact on EA and CL, as mediated via CX in pandemic situations. Our study offers key implications for destinations to develop tactics in surviving during a pandemic to rebuild tourism.