Series Solution-Based Approach for the Interlaminar Stress Analysis of Smart Composites under Thermo-Electro-Mechanical Loading

This paper introduces a new loading condition considering the combined thermo-electro-mechanical coupling effect in a series solution-based approach to analyze the free-edge interlaminar stresses in smart composite laminates. The governing equations are developed using the principle of complementary virtual work. The assumed stress fields satisfy the traction-free and free-edge boundary conditions. The accurate stress states of the composite structures are acquired through the procedure of generalized eigenvalue problems. The uniform temperature is employed throughout the laminate, and the electric field loading is applied to the symmetric piezo-bonded actuators to examine the combined effect of thermal and electrical stresses on the overall deformation of smart composite laminates. It was observed that the magnitude of the peeling stresses generated by mechanical loading was reduced by the combined thermal and electric excitation loading (up to 25.3%), which in turn resulted in expanding the service life of the smart composite structures. The proposed approach is implemented on three different layup configurations. The efficiency of the current methodology is confirmed by comparing the results with the 3D finite element (FEM) solution computed by ABAQUS.

Experiment and Analysis of Mechanical Properties of Lightweight Concrete Prefabricated Building Structure Beams

Recent years have witnessed that the prefabricated concrete structure is in the widespread use of building structures. This structure, however, still has some weaknesses, such as excessive weight of components, high requirements for construction equipment, difficult alignment of nodes, and poor installation accuracy. In order to handle the problems mentioned above, the prefabricated component made of lightweight concrete is adopted. At the same time, this prefabricated component is beneficial to reducing the load of the building structure itself and improving the safety and economy of the building structure. Nevertheless, it is rarely found that the researches and applications of lightweight concrete for stressed members are conducted. In this context, this paper replaces ordinary coarse aggregate with lightweight ceramsite or foam based on the C60 concrete mix ratio so as to obtain a mix ratio of C40 lightweight concrete that meets the engineering standards. Besides, ceramsite concrete beams and foamed concrete beams are fabricated. Moreover, through three-point bending tests, this paper further explores the mechanical properties of lightweight concrete beams and plain concrete beams during normal use conditions. As demonstrated in the results, the mechanical properties of the foamed concrete beam are similar to those of the plain concrete beam. Compared to plain concrete beams, the density of foamed concrete beams was lower by 23.4%; moreover, the ductility and toughness of foamed concrete were higher by 13% and 3%, respectively. However, in comparison with the plain concrete beam, the mechanical properties of the ceramsite concrete beam have some differences, with relatively large dispersion and obvious brittle failure characteristics. Moreover, in consideration of the nonlinear deformation characteristics of reinforced concrete beams, the theoretical calculation value of beam deflection was given in this paper based on the assumption of flat section and the principle of virtual work. The theoretically calculated deflection values of ordinary concrete beams and foamed concrete beams are in good agreement with the experimental values under normal use conditions, verifying the rationality and effectiveness of the calculation method. The research results of this paper can be taken as a reference for similar engineering designs.

Sound Insulation Performance of Composite Double Sandwich Panels with Periodic Arrays of Shunted Piezoelectric Patches

The existing sandwich structure of the aircraft cabin demonstrates a good sound insulation effect in medium and high frequency bands, but poor in the low frequency band. Therefore, we propose an infinite new lightweight broadband noise control structure and study its sound transmission loss (STL). The structure is an orthogonally rib-stiffened honeycomb double sandwich structure with periodic arrays of shunted piezoelectric patches, and demonstrates lighter mass and better strength than the existing sandwich structure. The structure is equivalent according to Hoff’s equal stiffness theory and the effective medium (EM) method. Using the virtual work principle for a periodic element, two infinite sets of coupled equations are obtained. They are solved by truncating them in a finite range until the solution converges. The correctness and validity of the model are verified by using simulation results and theoretical predictions. Eventually, a further study is performed on the factors influencing the STL. All the results demonstrate that the STL in low-frequency can be improved by the structure, and the sound insulation bandwidth is significantly broadened by adding shunted piezoelectric patches. The structure can provide a new idea for the design of broadband sound insulation.

Smart control of functionally graded sandwich plates by incorporating Murakami zig-zag function

This study is aimed at incorporating the zig-zag effect by Murakami zig-zag function in the development of a finite element model for active constraining layer damping treatment of functionally graded sandwich plates. The present sandwich construction consists of functionally graded facings distanced by a ceramic core. The substrate functionally graded plate is subjected to active constraining layer damping treatment, which in itself is a two-layered material system comprised of a viscoelastic layer and a 1–3 piezoelectric composite layer. The deformation kinematics of the functionally graded sandwich plate active constraining layer damping system is shaped using Murakami zig-zag function , and the finite element model is obtained by the virtual work principle. A standard feedback control system has been implemented, and a MATLAB subroutine has been developed to present the open- and closed-loop responses. Substrate plates with functionally graded configurations 1-1-1, 1-2-1, and 2-1-2 are considered to evaluate the effect of active constraining layer damping on damping the frequency responses of these plates. Investigation on damping performance has been carried out, bearing in mind the change in power-law index with top and bottom ceramic-/metal-rich surfaces. Also, the effect of variation in fiber orientation angle (obliquely reinforced) of the piezoelectric composite material on the active constraining layer damping performance has been examined thoroughly.

A Five Variable Refined Plate Theory For Thermal Buckling Analysis Uniform And Nonuniform Of Cross-Ply Laminated Plates

This research is devoted to investigating the thermal buckling analysis behaviour of laminated composite plates subjected to uniform and non-uniform temperature fields by applying an analytical model based on a refined plate theory (RPT) with five unknown independent variables. The theory accounts for the parabolic distribution of the transverse shear strains through the plate thickness and satisfies the zero-traction boundary condition on the surface without using shear correction factors; hence a shear correction factor is not required. The governing differential equations and associated boundary conditions are derived by using the virtual work principle and solved via Navier-type analytical procedure to obtain critical buckling temperature. Results are presented for: uniform and linear cross-ply lamination with symmetry and antisymmetric stacking, simply supported boundary condition, different aspect ratio (a/b), various orthogonality ratio (E1/E2), varying ratios of coefficient of uniform and linear thermal expansion (α2⁄α1), uniform and linearly varying temperature thickness ratio (a/h) and numbers of layers on thermal buckling of the laminated plate. It can be concluded that this theory gives good results compared to other theories.

Flexible Environments for Hybrid Collaboration: Redesigning Virtual Work Through the Four Orders of Design

The COVID-19 pandemic made visceral for many the fact that virtual forms of collaboration— simultaneously liberating and frustrating—are here to stay. Workers’ frustrations demonstrate that challenges remain for work and its design in increasingly “hybrid” collaboration— work in which some people, interacting face-to-face, are co-located while others with whom they work are remote. Using Buchanan's four orders of design, in conjunction with management and information systems scholarship, we present a framework for improving these virtual forms of collaboration. In this article, we review the latest knowledge from these disciplines on virtual collaboration through the lens of the four orders of design. In doing so, we demonstrate that conceiving of work in terms of flexible collaborative environments could increase the unity of purpose between work and workers by leveraging the capabilities of varying degrees of virtuality to engender experiences that benefit all those who interact with work systems.

63 Virtual Community Outreach Simulation Programme

The community outreach programme paused during the global pandemic as schools were closed and we were unable to go into schools and colleges to use simulation-based training to educate and inspire young adults to consider a career in the National Health Service. Now that schools and colleges are open it is still difficult to go into schools and colleges due to COVID-19 restrictions. We needed a way to continue to reach out to these schools and colleges using simulation to educate and inspire young adults.The aim was to continue the outreach programme but virtually, via live streams and some pre-recorded simulations. Aiming to help to increase awareness of the different careers, routes into the National Health Service and skills required to work in healthcare. ‘A virtual learning environment is intended not simply to reproduce a classroom environment -’on-line’, but to use the technology to provide a new way of learning’, Britain and Liber [1]. By continuing to provide the outreach simulation project I hope to be able to engage with a larger number of learners at a single time.Streaming live simulations sessions with tutor groups from schools and colleges via platforms such as Microsoft Teams and Zoom using a variety of simulation scenarios. These simulations will be mainly focussing on human factors with some teaching on specific subjects depending on the need of the learners. Example: Virtual work experience for young adults interested in medicine. We plan to mock up our simulation centre to replicate an accident and emergency department and have three admissions of different severity. We will be streaming this to two schools simultaneously and they will have the chance to help prioritize the three patients and explain their choice. The simulations will display good teamwork, good communications skills and leadership. One of the simulations will not include these skills and display poor communication, this will be intentionally included in a simulation for the learners to identify.Feedback forms will be given to all learners to complete asking them if the session has inspired them to consider a career in the National Health Service, feedback will then be used to adjust the way we deliver the virtual side of the outreach programme and perfect the programme so we can continue to educate and inspire young adults.

The potential of virtual global mobility: implications for practice and future research

PurposeThe COVID-19 pandemic has forced global organizations to adopt technology-driven virtual solutions involving faster, less costly and more effective ways to work worldwide even after the pandemic. One potential outcome may be through virtual global mobility (VGM), defined as the replacement of personal physical international interactions for work purposes with electronic personal online interactions. The purpose of this article is to establish VGM as a theoretical concept and explore to what extent it can replace or complement physical global work assignments.Design/methodology/approachThis perspectives article first explores advantages and disadvantages of global virtual work and then discusses the implementation of VGM and analyses to what extent and how VGM can replace and complement physical global mobility.FindingsRepresenting a change of trend, long-term corporate expatriates could become necessary core players in VGM activities while the increase of the number of global travelers may be halted or reversed. VGM activities will grow and further develop due to a continued rapid development of communication and coordination technologies. Consequently, VGM is here to stay!Originality/value The authors have witnessed a massive trend of increasing physical global mobility where individuals have crossed international borders to conduct work. The authors are now observing the emergence of a counter-trend: instead of moving people to their work the authors often see organizations moving work to people. This article has explored some of the advantages, disadvantages, facilitators and barriers of such global virtual work. Given the various purposes of global work the authors chart the suitability of VGM to fulfill these organizational objectives.