V. V. Singh, Abubakkar Idris Mohhammad, Kabiru Hamisu Ibrahim and Ibrahim Yusuf
This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The…
Abstract
Purpose
This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable system performability analysis.
Design/methodology/approach
In this paper, the authors have analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The supplementary variable technique has employed for analyzing the performance of the system.
Findings
Reliability measures have been computed for different types of configuration. It generalized the results for purely series and purely parallel configurations.
Research limitations/implications
This research may be beneficial for industrial system performances whereas a k-out-of-n-type configuration exists.
Practical implications
Not sure as it is a theoretical assessment.
Social implications
This research may not have social implications.
Originality/value
This work is the sole work of authors that have not been communicated to any other journal before.
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Ritesh Kumar, Himanshu Pathak, Akhilendra Singh and Mayank Tiwari
The purpose of this paper is to analyze the repair of a straight and angular crack in the structure using a piezoelectric material under thermo-mechanical loading by the extended…
Abstract
Purpose
The purpose of this paper is to analyze the repair of a straight and angular crack in the structure using a piezoelectric material under thermo-mechanical loading by the extended finite element method (XFEM) approach. This provides a general and simple solution for the modeling of crack in the structure to analyze the repair.
Design/methodology/approach
The extended finite element method is used to model crack geometry. The crack surface is modeled by Heaviside enrichment function while the crack front is modeled by branch enrichment functions.
Findings
The effectiveness of the repair is measured in terms of stress intensity factor and J-integral. The critical voltage at which patch repair is most effective is evaluated and presented. Optimal patch shape, location of patch, adhesive thickness and adhesive modulus are obtained for effective repair under thermo-mechanical loading environment.
Originality/value
The presented numerical modeling and simulation by the XFEM approach are of great benefit to analyze crack repair in two-dimensional and three-dimensional structures using piezoelectric patch material under thermo-mechanical loading.
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Rajul Garg, Harishchandra Thakur and Brajesh Tripathi
The study aims to highlight the behaviour of one-dimensional and two-dimensional fin models under the natural room conditions, considering the different values of dimensionless…
Abstract
Purpose
The study aims to highlight the behaviour of one-dimensional and two-dimensional fin models under the natural room conditions, considering the different values of dimensionless Biot number (Bi). The effect of convection and radiation on the heat transfer process has also been demonstrated using the meshless local Petrov–Galerkin (MLPG) approach.
Design/methodology/approach
It is true that MLPG method is time-consuming and expensive in terms of man-hours, as it is in the developing stage, but with the advent of computationally fast new-generation computers, there is a big possibility of the development of MLPG software, which will not only reduce the computational time and cost but also enhance the accuracy and precision in the results. Bi values of 0.01 and 0.10 have been taken for the experimental investigation of one-dimensional and two-dimensional rectangular fin models. The numerical simulation results obtained by the analytical method, benchmark numerical method and the MLPG method for both the models have been compared with that of the experimental investigation results for validation and found to be in good agreement. Performance of the fin has also been demonstrated.
Findings
The experimental and numerical investigations have been conducted for one-dimensional and two-dimensional linear and nonlinear fin models of rectangular shape. MLPG is used as a potential numerical method. Effect of radiation is also, implemented successfully. Results are found to be in good agreement with analytical solution, when one-dimensional steady problem is solved; however, two-dimensional results obtained by the MLPG method are compared with that of the finite element method and found that the proposed method is as accurate as the established method. It is also found that for higher Bi, the one-dimensional model is not appropriate, as it does not demonstrate the appreciated error; hence, a two-dimensional model is required to predict the performance of a fin. Radiative fin illustrates more heat transfer than the pure convective fin. The performance parameters show that as the Bi increases, the performance of fin decreases because of high thermal resistance.
Research limitations/implications
Though, best of the efforts have been put to showcase the behaviour of one-dimensional and two-dimensional fins under nonlinear conditions, at different Bi values, yet lot more is to be demonstrated. Nonlinearity, in the present paper, is exhibited by using the thermal and material properties as the function of temperature, but can be further demonstrated with their dependency on the area. Additionally, this paper can be made more elaborative by extending the research for transient problems, with different fin profiles. Natural convection model is adopted in the present study but it can also be studied by using forced convection model.
Practical implications
Fins are the most commonly used medium to enhance heat transfer from a hot primary surface. Heat transfer in its natural condition is nonlinear and hence been demonstrated. The outcome is practically viable, as it is applicable at large to the broad areas like automobile, aerospace and electronic and electrical devices.
Originality/value
As per the literature survey, lot of work has been done on fins using different numerical methods; but to the best of authors’ knowledge, this study is first in the area of nonlinear heat transfer of fins using dimensionless Bi by the truly meshfree MLPG method.
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Anjali Singh and Sumi Jha
This study explores the critical role of strategic leadership in driving organizational innovation amid rapid technological advancements. It delves into how strategic leaders…
Abstract
This study explores the critical role of strategic leadership in driving organizational innovation amid rapid technological advancements. It delves into how strategic leaders, including top management teams and CEOs, capitalize on technological changes to foster innovation and sustain competitiveness. By employing bibliometric analysis, the research identifies pivotal themes within strategic leadership literature, highlighting the importance of adaptable leadership styles, executive influence, and the emergent role of social capital. The study underscores the necessity for strategic leaders to dynamically adjust their strategies to navigate the evolving technological landscape effectively. Through an extensive review, it offers insights into how leadership practices can drive organizational success in an era of technological disruption. This research not only extends the theoretical framework of strategic leadership in the context of technological innovation but also offers practical implications for leaders aiming to cultivate a culture of innovation within their organizations.
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Muhamad Husnain Mohd Noh, Mohd Akramin Mohd Romlay, Chuan Zun Liang, Mohd Shamil Shaari and Akiyuki Takahashi
Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable…
Abstract
Purpose
Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable crack growth until a complete fracture happens. The SIF calculation of the materials can be conducted by experimental, theoretical and numerical techniques. Prediction of SIF is crucial to ensure safety life from the material failure. The aim of the simulation study is to evaluate the accuracy of SIF prediction using finite element analysis.
Design/methodology/approach
The bootstrap resampling method is employed in S-version finite element model (S-FEM) to generate the random variables in this simulation analysis. The SIF analysis studies are promoted by bootstrap S-version Finite Element Model (BootstrapS-FEM). Virtual crack closure-integral method (VCCM) is an important concept to compute the energy release rate and SIF. The semielliptical crack shape is applied with different crack shape aspect ratio in this simulation analysis. The BootstrapS-FEM produces the prediction of SIFs for tension model.
Findings
The mean of BootstrapS-FEM is calculated from 100 samples by the resampling method. The bounds are computed based on the lower and upper bounds of the hundred samples of BootstrapS-FEM. The prediction of SIFs is validated with Newman–Raju solution and deterministic S-FEM within 95 percent confidence bounds. All possible values of SIF estimation by BootstrapS-FEM are plotted in a graph. The mean of the BootstrapS-FEM is referred to as point estimation. The Newman–Raju solution and deterministic S-FEM values are within the 95 percent confidence bounds. Thus, the BootstrapS-FEM is considered valid for the prediction with less than 6 percent of percentage error.
Originality/value
The bootstrap resampling method is employed in S-FEM to generate the random variables in this simulation analysis.
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I.V. Singh, Masataka Tanaka, J. Zhang and M. Endo
The purpose of this paper is to evaluate the thermal properties of carbon nanotube composites via meshless element free Galerkin (EFG) method.
Abstract
Purpose
The purpose of this paper is to evaluate the thermal properties of carbon nanotube composites via meshless element free Galerkin (EFG) method.
Design/methodology/approach
The EFG method is based on moving least square approximation, which is constructed by three components: a weight function associated with each node, a basis function and a set of non‐constant coefficients. In principle, EFG method is almost identical to finite element method. The EFG method does not require elements for the interpolation (or approximation) of field variable, but only requires a set of nodes for the construction of approximation function.
Findings
The equivalent thermal conductivity of the composite has been calculated, and plotted against nanotube length, nanotube radius, RVE length, and RVE radius. Temperature distribution has been obtained and plotted with RVE length. An approximate numerical formula is proposed to calculate the equivalent thermal conductivity of CNT‐composites. Present computations show that the addition of 6.2 per cent (by volume) of CNT in polymer matrix increases the thermal conductivity of the composite by 42 per cent, whereas 16.1 per cent of CNT addition increases the thermal conductivity of the composite by 352 per cent.
Research limitations/implications
An ideal model, i.e. representative volume element containing single CNT has been taken to evaluate the thermal properties of CNT‐composites.
Practical implications
A simplified approach based on EFG method has been developed to evaluate the overall thermal conductivity of the CNT‐composites.
Originality/value
Continuum mechanics‐based mesh‐free EFG method has been successfully implemented for the thermal analysis of CNT‐composites.
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The purpose of this paper is to study the flow and heat transfer characteristics of a phase transition, melting problem. In this problem, phase transition between solid and liquid…
Abstract
Purpose
The purpose of this paper is to study the flow and heat transfer characteristics of a phase transition, melting problem. In this problem, phase transition between solid and liquid takes place within a square enclosure in the presence of natural convection.
Design/methodology/approach
The physical problem, described with non-linear partial differential equations, is simulated using a hybrid finite element and element free Galerkin method (FEM/EFGM) approach. In energy conservation equation, the fixed-domain, effective heat capacity method is used to take into account the latent heat of phase change. The governing partial differential equations are solved with a meshfree, EFGM near the phase transition front while in the region away from the front with uniform nodal distribution; problem is simulated with traditional FEM.
Findings
A sensitivity analysis of characteristic dimensionless numbers Rayleigh number (Ra), Prandtl number (Pr), Stefan number (ste) is presented in order to investigate their impact on thermal and flow fields. Typically computational times of EFGM are higher than that of FEM. Therefore, by using EFGM only in that portion of physical problem where phase transition occurs, the hybrid FEM/EFGM strategy employed in present paper could reduce the computational time of EFGM while still retaining its accuracy. Also, the consistent performance of the results obtained with this hybrid approach is validated with those already available in literature for some special cases.
Originality/value
The hybrid methodology adopted in this paper, is quite new for solving such type of phase transition problem.
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Zhiyong Wang, Jing Gu, Cheng Hou and Ming Song
The purpose of this paper is to propose the interaction integral method combing with a XFEM-based local mesh replacement method to evaluate both the stress intensity factors…
Abstract
Purpose
The purpose of this paper is to propose the interaction integral method combing with a XFEM-based local mesh replacement method to evaluate both the stress intensity factors (SIFs) and T-stress at the crack tip near a circular inclusion.
Design/methodology/approach
Special attention is pay to the effect of T-stress on crack initiation angle in 2D composite medium. The generalized maximum tangential stress criterion is employed during the simulation which simultaneously involves the effects of the mixed-mode SIFs, the T-stress and a physical length scale rc (the size of the fracture process zone).
Findings
It is shown that T-stress could affect the crack initiation angle significantly for mixed-mode conditions. Varies types of material mismatch are also considered and their influences on T-stress are given quantitatively.
Originality/value
The proposed numerical method allows a considerable flexibility for such problems and provides a basic framework for quasi-static crack growth in materials containing complex interfaces.
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Amanpreet Singh, Gurmeet Singh and Satish Kumar
The purpose of this paper is to demonstrate the erosion performance of coated and uncoated surfaces of glass fibre-reinforced polymers (GFRP) wind turbine blade material using…
Abstract
Purpose
The purpose of this paper is to demonstrate the erosion performance of coated and uncoated surfaces of glass fibre-reinforced polymers (GFRP) wind turbine blade material using Taguchi's approach. Taguchi's array (L25) optimized erosion wear by varying three parameters: impact velocity, impact angle and run time across five levels.
Design/methodology/approach
The studies were carried out using a whirling arm rig tester with an impact velocity range of 30–70 m/s (metre per second), an impact angle of 0–90 degree and a run time of 30–90 min. Salt water is used as an erosion agent to replicate the offshore environment. Taguchi's method was used to optimize the process parameters.
Findings
The results showed that erosion is less on the coated surface than on the uncoated surface. When compared to other factors, impact velocity was determined to be the most dominant, whereas run time was the least dominant. In addition, GFRP wind turbine blade material exhibits a ductile erosion process. Furthermore, in all experimental trials less erosion was observed on coated surfaces as compared to uncoated surfaces.
Originality/value
Few researches have been done using different design of experiment techniques to optimize the erosion wear response of uncoated GFRP materials and coatings based on polyurethane. Furthermore, mechanism of the erosion and morphology of both surface conditions was investigated using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy testing and Minitab software.
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Abdulkareem Lado Ismail, Sanusi Abdullahi and Ibrahim Yusuf
This study deals with the reliability analysis of a hybrid series–parallel system consisting of two subsystems A and B with two human operators. Subsystem A has two units in…
Abstract
Purpose
This study deals with the reliability analysis of a hybrid series–parallel system consisting of two subsystems A and B with two human operators. Subsystem A has two units in active parallel while subsystem B consists of two-out-of-four units. Both units have exponential failure and repair time. The system under consideration has two states: partial failure state and complete failure state. The mathematical equations associated with the transition diagram have been formulated using regenerative point techniques. The system is analysed using Laplace transforms to solve the mathematical equations. Some important measures of reliability such as availability of system, reliability of the system, mean time to failure (MTTF), sensitivity for MTTF and cost analysis have been discussed. Some particular cases have also been derived and examined to see the practical effect of the model. The computed results are demonstrated by tables and graphs. Furthermore, the results of the designed model are beneficial for system engineers and designers, reliability and maintenance managers.
Design/methodology/approach
This paper considered a hybrid series–parallel system consisting of two subsystems A and B with two human operators. The performance of the system is studied using the supplementary variable technique and Laplace transforms. The various measures of reliability such as availability, reliability, mean time to system failure (MTSF), sensitivity for MTTF and cost analysis have been computed for various values of failure and repair rates. Maple 13 software has been used for computations.
Findings
In this research paper, the authors have computed various measures of reliability such as availability, reliability, MTSF, sensitivity for MTTF and cost analysis for various values of failure and repair rates and find that failure due to human operators are more responsible for successful operation of the system and also regular repair should be invoked to improve system performance.
Originality/value
This research paper is the original work of authors. The references are well cited based on the importance of study. Nothing has been detached from any research paper or books.