Showing papers on "Virtual work published in 2023"

Bending Analysis of Laminated Composite Cylindrical Shell Using Fifth Order Shear Deformation Theory

Abstract: AbstractIn the present study, a fifth order shear and normal deformation theory is extended for the bending analysis of laminated composite cylindrical shells. The effect of transverse normal and shear deformations is included to predict the displacement and stresses. The governing equations are derived using principle of virtual work, and solved by using Navier’s technique. The accuracy and efficacy of the present theory is checked by comparing the present results with those available in the literature.KeywordsCylindrical shellLaminated compositeShear deformation

Buckling of Coated Functionally Graded Spherical Nanoshells Rested on Orthotropic Elastic Medium

Abstract: Coated functionally graded materials (FGMs) are used in several industrial structures such as turbine blades, cutting tools, and aircraft engines. Given the need for analytical and numerical analysis of these complex structures, a mathematical model of tricoated FG structures is presented for the first time in this paper. The objective of this work was to analyze analytically the buckling problem of unidirectional (1D), bidirectional (2D), and tridirectional (3D) coated FG spherical nanoshells resting on an orthotropic elastic foundation subjected to biaxial loads. Based on the generalized field of displacement, a 2D higher-order shear deformation theory was proposed by reducing the number of displacement variables from five to four variables for specific geometry cases. The nonlocal strain gradient theory was employed to capture the size-dependent and microstructure effects. The equilibrium equations were performed by applying the principle of the virtual work, and the obtained differential equations were solved by applying the Galerkin technique to cover all possible boundary conditions. The proposed elastic foundation was defined based on three parameters: one spring constant and two shear parameters referring to the orthotropy directions. A detailed parametric analysis was carried out to highlight the impact of various schemes of coated FGMs, gradient material distribution, length scale parameter (nonlocal), material scale parameter (gradient), geometry of the nanoshell, and variation in the orthotropic elastic foundation on the critical buckling loads.

A look at the future of work: The digital transformation of teams from conventional to virtual

Abstract: This study addresses the challenges of digitally transforming teams from conventional to virtual environments in response to the unique conditions of a global pandemic lock-down and the need for business survival, rather than as a proactive strategic move initiated and encouraged by senior management. Based on dynamic capabilities theory, we use 18 in-depth interviews to identify the skills and capabilities required for successful transition at the individual and organizational levels. First, at the individual level, communication differences (i.e., informal vs. formal, spontaneous vs. structured, and synchronous vs. sequential) were identified when comparing conventional and virtual teams. Second, at the organizational level, this study identified several challenges related to the digital transformation of teams (e.g., onboarding challenges, barriers in the virtual environment, structural challenges, new team roles such as change manager, chief officer of happiness, etc.). Finally, seven different digital dynamic capabilities are proposed for teams transforming to a virtual environment.

Effects of transverse normal strain on the deformation of laminated and sandwich arches under the action of concentrated force

Abstract: It is well-known that the concentrated force develops high-stress concentration at the point of application which is one of the important parameters to be considered while designing the laminated composite structures under the action of concentrated force. The literature available shows that the study on static deformation of laminated sandwich shallow arches under the action of the concentrated force is limited. In the present study, static deformation of laminated sandwich arches under the action of concentrated loading is investigated using higher-order arch theory considering the effects of transverse normal strain. An exponential type higher-order arch theory is developed in this study which satisfies the traction-free boundary conditions at the top and the bottom surfaces of the arch using constitutive relations. Governing equations are derived within the framework of the principle of virtual work. An analytical solution for the static deformation of simply supported laminated and sandwich shallow arches are obtained using Navier’s technique. The effects of the lamination scheme, radius of curvature and aspect ratio on the deflection, and stresses of shallow arches are evaluated. The present results are compared with previously published results wherever possible for the verification of the present theory.

Elastodynamics of an overconstrained 8-SS platform for touchdown impact force measurement

Abstract: Passive overconstrained parallel mechanism has many advantages due to extra constraints to the platform. When applied to the force sensor field, it can increase the capability, stiffness and dynamic response of the sensor. In this study, an overconstrained [Formula: see text] platform is presented to measure the multi-dimensional landing impact force. Screw theory is used to obtain the concentrated inertia force. Then, by adding the inertial force into the VJM (Virtual Joint Method) stiffness model, the static analysis is extended to elastodynamics analysis. Natural frequency and modal are derived from the elastodynamics equation and show well agreement with the FEA result in Abaqus. Theoretical force measurement equation is deduced. The FEA simulation result proves the effectiveness of the theoretical equation. Experiments are also conducted to verify the feasibility of the platform.

Unified plate finite elements for the large strain analysis of hyperelastic material structures

Abstract: This paper proposes a high-order two-dimensional (2D) finite element model for the analysis of isotropic, nearly incompressible hyperelastic material structures based on a decoupled neo-Hookean strain energy function. The model is based on the Carrera Unified Formulation (CUF) , which allows to automatically implement different kinematics by using an opportune recursive notation. The principle of virtual work and a finite element approximation are exploited to obtain the nonlinear governing equations. Considering the three-dimensional full Green–Lagrange strain components and given the material Jacobian tensor, the explicit forms of tangent stiffness matrices of unified plate elements are presented in terms of the fundamental nuclei, which are independent of the theory approximation order. Several problems of soft material plates under uniform pressure are investigated, including a silicone rubber clamped plate and a simply supported plate made of biological material. The proposed model is compared with literature results including those coming from experiments and numerical solutions. The numerical investigation demonstrated the validity and accuracy of the proposed methodology for the analysis of hyperelastic plates.

Effects of Transverse Normal Stress on Hygrothermomechanical Analysis of Laminated Shallow Shells

Abstract: Hygrothermomechanical analysis of doubly curved laminated composite shallow shells is presented in this paper using a two-dimensional higher-order shell theory considering the effects of transverse normal stress. The present theory accounts for the fifth-order expansion of the thickness coordinates in the in-plane displacements and the fourth-order expansion in the transverse displacement. The main focus of this work is to study the effects of both transverse normal stress and the fifth-order expansion of thickness coordinates on the hygrothermomechanical responses of doubly curved laminated shallow shells. The governing equations of the theory are derived based on the principle of virtual work and solved by using Navier’s method. The theory ensures traction-free boundary conditions using constitutive relations and does not require a shear correction factor. Interlaminar transverse shear stresses are recovered using the three-dimensional equilibrium equations of the theory of elasticity to ascertain the stress continuity at the layer interface. Three-dimensional elasticity solutions are taken as a basis for comparing the present results in thermal problems, whereas this study contributes some useful results to the hygrothermomechanical analysis of doubly curved laminated composite shallow shells.

Analysis of Vibration Characteristics of Electro-hydraulic 3-UPS/S Parallel Stabilized Platform

Abstract: Abstract With the development of fluid power transmission and control and control technology, using electro-hydraulic driven can significantly improve the load-carrying capacity, stiffness, and control accuracy of the stabilization platforms. However, compared to mechanical driven, electro-hydraulic driven parallel stabilization platform needs to consider the stiffness and damping of the fluid, as well as the coupling effect between the fluid and the structure, making the modal and dynamic response characteristics of the mechanism more complex. Aiming at the above problems, taking the electro-hydraulic driven 3-UPS/S parallel stable platform as the research object, considering the hinge stiffness, the vibration characteristic equation of the mechanism was established by using the virtual work principle. Then the variation characteristics of natural frequency and vibration response with the position of mechanism were analyzed basing on the dynamic equation. Finally, the correctness of the model was verified by modal test and Runge-Kutta methods. This study can provide a theoretical basis for the dynamic design of electro-hydraulic driven parallel mechanisms.

Análisis Estructural aplicando el Principio del trabajo Virtual en pórticos isostáticos en Chanchamayo

Abstract: The objective of the investigation was to carry out the structural analysis in isostatic frames in the buildings. The scope is descriptive-comparative, it uses the principle of virtual work, the instrument used for the calculations is the calculation of reactions, equilibrium in real system elements, virtual system and deflections). It is argued that the structural analysis of static frames is the determination of linear or angular displacements, through the analysis of the external forces that cause deformations (c) and stresses (σ) in hyperstatic or isostatic structures. From this, the results were compared with the FTOOL and SAP2000 software. The most relevant results were the deflections at node B with a value of 42.5385 m and the horizontal displacements at node B with a value of 26.009 mm. In the end, it is concluded that the flat reinforcement that was studied under certain aforementioned conditions presented as structural response displacements in the GDL 3,4,6,7, of the reinforcement, where internal forces were produced for all the bars and displacements due to the settlement effect in the entire structure. That said, the results were corroborated and compared manually and using engineering software such as Sap2000 and Ftool.

Hybrid and virtual work settings; the interaction between technostress, perceived organisational support, work-family conflict and the impact on work engagement

Abstract: PurposeThe study assessed the impact of technostress creators, work–family conflict and perceived organisational support (POS) on work engagement for employees operating within the virtual and hybrid work settings. The idea is to redefine the antecedents of work engagement in work settings that are characterised by excessive technology and work–family conflict.Design/methodology/approachData gathered from 302 academics and support staff employees at a selected university in South Africa were utilised to assess the abovementioned relationships via variance-based structural equation modelling.FindingsThe combined effect of technostress, work–family conflict and POS on work engagement indicates that work–family conflict is a critical component in the relationship between technostress and work engagement. Although POS is seen as a job resource that lessens stress, the study found that the influence of work–family conflict is stronger than that of POS; hence, a negative influence is reported on work engagement. Despite the presence of support, overwhelming technostress creators and work–family conflict issues increase demands and influence work engagement negatively.Research limitations/implicationsThe results noted that, in hybrid and virtual work settings, managers can drive employee engagement by focussing on designing more favourable work–life balance (WLB) policies, providing adequate information communication technology (ICT) support, fostering aspects of positive technology and defining the boundaries between work life and family time.Practical implicationsThe managers need to realise the detrimental effects of both technostress and work–family conflict on work engagement in virtual and hybrid work settings. Expanding the personal and job resources of individuals in hybrid and virtual settings is critical to enable them to meet the additional work demands and to manage the strain imposed by technostress. Instituting relevant organisation support has proved to be inadequate to address the challenges relating to technostress and work–family conflict. Therefore, introducing WLB policies that assist employees to set clear boundaries between work and family time to avoid burn out and spillover is critical. This is especially important when dealing with technostress creators in the remote work setting. Additionally, providing adequate ICT support as well as training related to use of different devices and software should be part of the organisational culture.Social implicationsA manageable and reasonable workload should be maintained bearing in mind the complexity and ambiguity associated with the hybrid work setting. Managers should make allowances for employees to adjust managers' schedules to accommodate personal obligations, as well as adjust employees' workloads to accommodate family responsibilities. As for the coping strategy of technostress and work–family conflict, considering the positive effects of the supportive work environment is important.Originality/valueThis study provides a model on the interaction of the redefined antecedents (technostress and work–family conflict) of work engagement in high-tech environments such as virtual and hybrid work settings.

Determining the centres of mass of a circular arc and a circular sector using the principle of virtual work

Abstract: In studying physics, it is important to solve problems with different methods and compare current and final results, which allows more comprehensive and deep analysis of the observed processes. In this paper, at a level of school physics course, the application of the principle of virtual work is presented as an alternative to the standard method for solving problems of statics. Two approaches are used to analyse two problems, as a result of which, without the use of integral calculus, formulas for the centres of mass of a circular arc and a circular sector are obtained.

Unified three-dimensional finite elements for large strain analysis of compressible and nearly incompressible solids

Abstract: This work proposes a displacement-based finite element model for large strain analysis of isotropic compressible and nearly-incompressible hyperelastic materials. Constitutive law is written in terms of invariants of the right Cauchy-Green tensor; coupled and decoupled formulations of strain energy functions are presented, whereas a penalty function is used to impose an incompressibility constraint. Based on a total Lagrangian formulation, the nonlinear governing equations are thus obtained by employing the principle of virtual displacements. Analytic expression of both internal forces vector and tangent matrix of linear and high-order hexahedral finite elements are derived by adopting a three-dimensional formalism based on the Carrera Unified Formulation. Popular benchmark problems in hyperelasticity are analyzed to establish the capabilities of the present implementation of fully-nonlinear solid elements in the case of compressible and nearly-incompressible beams, cylindrical shells, and curved structures.

Quasi-Coordinates-Based Closed-Form Dynamic Modeling and Analysis for a 2R1T PKM with a Rigid–Flexible Structure

Abstract: This work derives a closed-form dynamic model for a two rotational and one translational degrees-of-freedom (2R1T) parallel kinematic mechanism (PKM) with a hybrid rigid–flexible structure for force-control applications. Based on the three-prismatic-prismatic-spherical (3PPS) kinematic configuration of the 2R1T PKM and its zero-torsion motion characteristics, a symbolic formulation approach is proposed to establish closed-form kinematic models for both forward and inverse kinematics analysis. As the moving platform pose of the 2R1T 3PPS PKM can be readily determined by the three active prismatic joint variables and the three passive prismatic joint variables, these six joint variables are selected as the quasi-coordinates so as to systematically develop the closed-form dynamic model with a Lagrangian formulation, in which the stiffness and deformation of the three flexure-based passive prismatic joints are uniformly taken into consideration. Through eliminating the three passive prismatic joint variables based on the principle of virtual work and the relationships between the active and passive prismatic joint variables, a closed-form dynamic model for the 2R1T 3PPS PKM with a rigid–flexible structure is finally obtained. The correctness of the closed-form dynamic model was validated with the commercial dynamic simulation software. Utilizing the closed-form dynamic model, the effects of different flexure stiffness in driving directions on the required active joint force were investigated, which indicated that little flexure stiffness in driving directions is desired.

Modeling and Analysis of Offshore Gangway under Dynamic Load

Abstract: The safety transfer on the sea is threatened by wind, wave and surge loads. An offshore gangway ensures smooth and safe transfer by compensating the ship’s motion. In a mixed offshore gangway system, the transfer gangway is a huge asymmetric load on top of the stable platform, and the displacement of its center of gravity causes it to exert a large dynamic load on the stable platform. A dynamic model of the offshore gangway under dynamic load is established in this work. The Lagrange equation is used to establish the dynamic model of the transfer gangway; the equivalent center of gravity method is used to visualize its dynamic load. The dynamic of the stable platform is modeled by the virtual work principle. Finally, the accuracy of the mathematical model was verified by the joint simulation. Simulation results indicate that under the influence of dynamic load, the tractive force of the second drive support chain is 2–3 times greater than the tractive force of the first and third drive support chains. With the same excitation, the tractive force of the second drive support chain is 2.83 times higher than that under the static load.

A new shear deformation theory in axiomatic framework for bending and buckling analysis of cross-ply and angle-ply laminated composite plates

Abstract: In this study, a new higher order hyperbolic shear deformation theory for mechanical analysis of cross-ply and angle-ply multi-layered plates is developed. Analytical solution to the static and buckling responses of symmetric and anti-symmetric composite laminates is presented. The proposed theory considers secant hyperbolic function of thickness coordinate in the displacement field. Also the developed theory assumes non-linear distribution of displacements and ensures that the top and lower surfaces of the plates have zero shear stresses. The equilibrium equations are obtained by applying the principle of virtual work (PVW). The stiffness characteristics of cross-ply and angle-ply laminates are taken into account when solving these governing equations. The closed-form Navier solution satisfying the corresponding boundary conditions are derived for simply supported (SS) composite plates. The results for non-dimensional deflections, and stresses of composite laminates under the effect of sinusoidal and uniform distributed load are thus obtained. The uni-axial and bi-axial loading force are used to evaluate critical buckling loads. Further, the impact of span-thickness ratio, aspect ratios, fiber orientation, and modulus ratio, etc. on static and buckling analysis plates is also studied. The validity of present formulation is demonstrated by comparing our results with some of the available results in literature.

Bending Analysis of Asymmetric Functionally Graded Material Sandwich Plates in Thermal Environments

Abstract: This paper investigates the bending of asymmetric functionally graded material (FGM) sandwich plates subjected to thermo-mechanical loads in thermal environments. In this paper, a thermo-mechanical analysis model for asymmetric FGM sandwich plates is proposed, which contains only four control equations and four unknown variables. The governing equation is obtained through refined shear theory and the principle of virtual work, and the Navier method is used to solve it. Numerical examples of simply supported FGM sandwich plates under thermo-mechanical loads are given to verify the accuracy of the model. Finally, detailed studies are conducted on the bending of asymmetric FGM sandwich plates under thermo-mechanical loads, exploring the effects of various parameter changes on their bending behavior, and providing strong guidance for the application of asymmetric FGM sandwich plates in industrial production practice.

Uniform and non-uniform thermal buckling analysis of laminated plates using five-variable refined theory

Abstract: Critical buckling temperature of cross ply and angle ply composite plate under uniform and non-uniform temperature distribution are investigated using refined plate theory (RPT) with five independent unknown variables. This theory accounts for the parabolic distribution of transvers shear strain through the thickness plate thickness and satisfies zero-traction surface boundary conditions without the use of shear correction factors. Equations of motion are derived and solved to find critical buckling temperature of composite laminated plate using the principle of virtual work. Computer program has been used to study the effect of design parameters such as thickness ratio (a/h), aspect ratio (a/b), orthogonality ratio (E1/E2), coefficient of thermal expansion ratio (α2⁄α1) and numbers of plies on critical buckling temperature. It was found that the obtained results were compared with other different theories and give good agreement. Furthermore, a parametrical study was also conducted to investigate the effect of these parameters on buckling temperature of simply supported symmetric and antisymmetric composite plate. Increasing orthotropy ratio and aspect ratio caused increasing critical buckling temperature while increasing thickness ratio and thermal coefficient expansion caused to decreasing critical buckling temperature.

Bouncing back as a virtual team: essential elements of virtual team resilience

Abstract: Organizational complexity fosters the creation of teams to effectively carry out work. As organizations globalize and adopt the use of virtual work, technology-driven communication and geographic dispersion both contribute to virtual team dynamics and carry the potential to challenge virtual teamwork. Virtual teams equipped to address and bounce back from adversity are poised to maintain or outperform expectations. This chapter discusses the empirical background that comprises virtual team resilience by distinguishing team resilience from individual and organizational-level definitions, stressing implications the virtuality context affords to clarify virtual team resilience. Following this, a multidimensional model for virtual team resilience is proposed. The model includes elements deemed essential to building virtual team resilience and explores how each element functions alongside four critical phases teams cyclically undergo. The chapter culminates with a discussion and recommendations for increasing and utilizing resilient behaviors when required.

Virtual Work as a Job Demand? Work Behaviors of Public Servants during Covid-19

Abstract: The study models the abrupt introduction of virtual work during the COVID-19 pandemic as a job demand within the Job Demands-Resources (JD-R) model. Using survey data from 1,173 public servants collected during the second national lockdown in Germany, we assess the relationships between several job and personal resources with organizational citizenship behavior (OCB), and the relationship between virtual work and counterproductive work behavior (CWB). Additionally, we analyze the moderating role of virtual work for the relationship of resources and OCB, as well as the moderating role of resources for the relationship of virtual work and CWB. Our results show that the direct effects of the resources and the demand for virtual work on workplace behaviors point in the expected direction, while only one out of ten hypothesized interaction effects could be found. These results contribute to theoretical insights about the multiplicative or additive nature of the JD-R model. In addition, virtual work relates positively to both CWB and OCB, which informs the debate about virtual work being a hindrance demand or a positive challenge in the public sector.

Bending Responses of Bi-Directional Advanced Composite Nanobeams Using Higher Order Nonlocal Strain Gradient Theory

Abstract: The bending response of two-dimensional (2D) functionally graded (FG) nonlocal strain gradient nanobeams is explored analytically in this work. The longitudinal and transverse orientations vary in material gradation and material characteristics. Kinematic relations of nanobeams are proposed according to hybrid hyperbolic-parabolic functions. The virtual work principle obtains the equilibrium equations, which are then solved using Navier's method. The accuracy and dependability of the suggested analytical model are demonstrated by comparing the results to predictions made in the literature. A thorough parametric study also determines how sensitive the material distribution, the nonlocal length-scale parameter, the strain gradient microstructure-scale parameter, and the geometry are to how the bending response and stresses of 2D FG nanobeams. The results obtained provide benchmark results, which can be used in the design of composite structures.

Organizational context and climate for virtual work

Abstract: In virtual work, organizational context and climate may affect employee well-being and performance in various ways. Research on this topic has accumulated over the past decades, but yet, a higher level integration of the findings is needed. This chapter reviews the literature on the contextual influences, such as place, space, and configuration of workers, as well as people management practices, including policies, norms and climate and their effects on employees in virtual work. Based on our review, we propose an agenda for future research and discuss practical implications for improving organizational context and human resources practices for virtual and hybrid work.

Kinematic and Static Modelling of a New Two-Degree-of-Freedom Cable Operated Joint

Abstract: This paper proposes a new two-degrees-of-freedom (dof) cable-actuated mechanism which can be utilized for lightweight variable-stiffness manipulators. Using numerical methods, a kinematic model for the proposed mechanism is derived for determining the mechanism’s configurations and cable lengths for a pair of independent task-space variables. The numerical algorithm used for estimating the workspace is cross-validated with a virtual prototype of the mechanism using ONSHAPE®. The work presented in the paper concludes with the static modelling of the mechanism, which yielded insights regarding the magnitude of the actuation forces, depending on the desired wrench-feasible workspace of the mechanism.