Mohd Rashid, Umesh S. Waware, Afidah A. Rahim and A.M.S. Hamouda
The purpose of this study is to compare the inhibitive effect of polyaniline (PAni) and N-cetyl-N,N,N trimethyl ammonium bromide (CTAB)-stabilized PAni in a hydrochloric acid…
Abstract
Purpose
The purpose of this study is to compare the inhibitive effect of polyaniline (PAni) and N-cetyl-N,N,N trimethyl ammonium bromide (CTAB)-stabilized PAni in a hydrochloric acid (HCl) medium.
Design/methodology/approach
PAni has been deposited potentiodynamically on mild steel in the presence of CTAB as a stabilizing agent to achieve high corrosion inhibition performance by the polymer deposition. The corrosion inhibition studies of CTAB-stabilized PAni inhibitor in 0.1 M HCl acidic solution was carried out by electrochemical methods, namely, open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy technique.
Findings
The results of electrochemical studies have shown that the CTAB-stabilized PAni inhibitor has higher corrosion efficiency than PAni on mild steel in 0.1 M HCl solution. The maximum per cent efficiency evaluated using the potentiodynamic polarization method is approximately 91.9.
Originality/value
CTAB-stabilized PAni has never been studied as a corrosion inhibitor for mild steel in an acidic medium. The investigations demonstrate relatively the better corrosion inhibition efficiency and high dispersion of the polymer in the acidic medium.
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Madjid Tavana and Vahid Hajipour
Expert systems are computer-based systems that mimic the logical processes of human experts or organizations to give advice in a specific domain of knowledge. Fuzzy expert systems…
Abstract
Purpose
Expert systems are computer-based systems that mimic the logical processes of human experts or organizations to give advice in a specific domain of knowledge. Fuzzy expert systems use fuzzy logic to handle uncertainties generated by imprecise, incomplete and/or vague information. The purpose of this paper is to present a comprehensive review of the methods and applications in fuzzy expert systems.
Design/methodology/approach
The authors have carefully reviewed 281 journal publications and 149 conference proceedings published over the past 37 years since 1982. The authors grouped the journal publications and conference proceedings separately accordingly to the methods, application domains, tools and inference systems.
Findings
The authors have synthesized the findings and proposed useful suggestions for future research directions. The authors show that the most common use of fuzzy expert systems is in the medical field.
Originality/value
Fuzzy logic can be used to manage uncertainty in expert systems and solve problems that cannot be solved effectively with conventional methods. In this study, the authors present a comprehensive review of the methods and applications in fuzzy expert systems which could be useful for practicing managers developing expert systems under uncertainty.
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Manish Garg, B S Salaria and V K Gupta
– The purpose of this paper is to investigate steady state creep behavior of a functionally graded rotating disc under varying thermal gradient (TG).
Abstract
Purpose
The purpose of this paper is to investigate steady state creep behavior of a functionally graded rotating disc under varying thermal gradient (TG).
Design/methodology/approach
The steady state creep in a rotating FGM disc with linearly varying thickness has been investigated by using von-Mises yield criterion. The disc under investigation is assumed to be made of FGM containing non-linear distribution of silicon carbide particle (SiCp) in a matrix of pure aluminum along the radial distance. The creep behavior of the FGM composite disc is described by threshold stress-based law. The stresses and strain rates in the FGM disc have been estimated for different kinds of TG.
Findings
The results indicate that when the FGM disc is subjected to a radial TG, with temperature increasing with increasing radius, the radial stress in the disc increases over the entire disc but the tangential and effective stresses increase near the inner radius and decrease toward the outer radius. The imposition of such a radial TG in the FGM disc leads to significant reduction in the radial and tangential strain rates. With the increase in magnitude of TG in the FGM disc, the inhomogeneity in creep stresses increases but the inhomogeneity in strain rates decreases significantly, thereby reducing the chances of distortion in the FGM disc.
Originality/value
The creep strain rates in rotating FGM disc could be significantly reduced when the disc is subjected to a radial TG, with temperature increasing with increasing radius.
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Royal Madan and Shubhankar Bhowmick
Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such…
Abstract
Purpose
Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such variations of materials, the properties of structure vary either lengthwise or thickness wise. This paper aims to investigate models for effective estimation of material properties, as it is necessary for industries to identify the properties of composites or functionally graded materials (FGM’s) before manufacturing and also to develop novel material combinations.
Design/methodology/approach
Available models were compared for different material combinations and tested with experimental data for properties such as Young’s modulus, density, coefficient of thermal expansion (CTE) and thermal conductivity. Combinations of metal–ceramic and metal–metal were selected such that their ratios cover a wide range of materials.
Findings
This study reveals different models will be required depending on the material used and properties to be identified.
Practical implications
The results of the present work will help researchers in the effective modeling of composites or FGM’s for any analysis.
Originality/value
This paper presents a comparison and review of various analytical methods with experimental data graphically to find out the best suitable method. For the first time, the Halpin-Tsai model was extended in the analysis of the CTE which shows good approximations.
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Xintian Liu and Muzhou Ma
Scholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue…
Abstract
Purpose
Scholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue damage models according to the actual situation. However, relatively few models can be generally accepted and widely used.
Design/methodology/approach
This review introduces the development of cumulative damage theory. Then, several typical models are selected from linear and nonlinear cumulative damage models to perform data analyses and obtain the fatigue life for the metal.
Findings
Considering the energy law and strength degradation, the nonlinear fatigue cumulative damage model can better reflect the fatigue damage under constant and multi-stage variable amplitude loading. In the following research, the complex uncertainty of the model in the fatigue damage process can be considered, as well as the combination of advanced machine learning techniques to reduce the prediction error.
Originality/value
This review compares the advantages and disadvantages of various mainstream cumulative damage research methods. It provides a reference for further research into the theories of cumulative fatigue damage.
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Royal Madan, Kashinath Saha and Shubhankar Bhowmick
The limit elastic speed of rotating disk is an important design criterion, as it defines the limit before onset of yielding initiates. The purpose of this paper is to establish…
Abstract
Purpose
The limit elastic speed of rotating disk is an important design criterion, as it defines the limit before onset of yielding initiates. The purpose of this paper is to establish the limit elastic speeds for S-FG disks and report the stresses induced at such speeds.
Design/methodology/approach
For S-FGM disk, effective Young’s modulus is calculated using modified rule of mixture and subsequently effective yield stress is also calculated by taking into consideration of stress-strain transfer ratio. The S-FGM disk is subject to centrifugal loading and the stress and deformation characteristics are investigated using variational principle wherein the solution is obtained by Galerkin’s error minimization principle. Based on von-Mises yield criteria, equivalent stress is calculated at different angular speeds till the equivalent stress at any given location in the disk attains the value of effective yield stress at the given location (location of yield initiation). This defines the limit elastic speed for the S-FGM disk (for given n).
Findings
The limit elastic speed of S-FGM disks for a range of grading index (n) and corresponding stresses within the disk are reported. Results are reported for uniform disks of different aspect ratio and the results reported could be used as practical design data.
Practical implications
Functional grading of material in structures opens a new horizon to explore the possibility of manufacturing high strength component at low weight. Material grading plays a significant role in achieving desired material properties, and literature review reveals reporting of numerous grading functions to approximate material distribution in structure.
Originality/value
The work has not been addressed earlier and findings provide a pioneering insight into the performance of S-FG disks.
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Royal Madan and Shubhankar Bhowmick
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material…
Abstract
Purpose
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material properties. Three different material models i.e. power law, sigmoid law and exponential law, along with varying disk profiles, namely, uniform thickness, tapered and exponential disk was considered.
Design/methodology/approach
The methodology adopted was variational principle wherein the solution was obtained by Galerkin’s error minimization principle. The Young’s modulus, coefficient of thermal expansion and yield stress variation were considered temperature-dependent.
Findings
The study shows a substantial increase in limit speed as disk profiles change from uniform thickness to exponentially varying thickness. At any radius in a disk, the difference in von Mises stress and yield strength shows the remaining stress-bearing capacity of material at that location.
Practical implications
Rotating disks are irreplaceable components in machinery and are used widely from power transmission assemblies (for example, gas turbine disks in an aircraft) to energy storage devices. During operations, these structures are mainly subjected to a combination of mechanical and thermal loadings.
Originality/value
The findings of the present study illustrate the best material models and their grading index, desired for the fabrication of uniform, as well as varying FG disks. Finite element analysis has been performed to validate the present study and good agreement between both the methods is seen.
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Gulshan Chauhan and T.P. Singh
Manufacturing organizations are under pressure to improve productivity and reduce costs through the realization of lean manufacturing. This paper approaches lean manufacturing and…
Abstract
Purpose
Manufacturing organizations are under pressure to improve productivity and reduce costs through the realization of lean manufacturing. This paper approaches lean manufacturing and aims to identify and measure the intimately associated parameters of lean manufacturing and also examines the weight of their contribution to overall lean manufacturing.
Design/methodology/approach
A questionnaire survey study was performed in Indian manufacturing industries to collect data. The reliability of the survey instrument was pre‐tested and an acceptable value of Cronbach's α (a reliability coefficient) was found. Three experts determined the relative weight of various parameters using analytical hierarchy process (AHP). Pearson's coefficient of correlation analysis was used to measure the strength of the relationships between various parameters of lean manufacturing.
Findings
The experts found “elimination of waste” to be the most important parameter of lean manufacturing, followed by “just in time deliveries”. The survey shows that most of the responding firms are in transition towards the realization of lean manufacturing. These firms believe that the factors that drive the realization of lean manufacturing are “just in time deliveries” and achieving “continuous improvement”. This study also revealed that Indian manufacturing industries are still overlooking the elimination of waste, the most important parameter of lean manufacturing.
Research limitations/implications
The major limitation of this paper is the sample size (n=52).
Practical implications
The present study provides guidelines to assess the status of leanness in the manufacturing industries. According to conclusions, feeble areas in the manufacturing system can be identified and a suitable course of action might be planned for the improvement. Hopefully this study will help the firm's management to identify the problems to implement an effective lean manufacturing.
Originality/value
In this work, the theoretical perspective was used not only to update the original instrument, but also to study the subject from a perspective beyond that usually associated with lean manufacturing.
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Natalia García-Fernández, Manuel Aenlle, Adrián Álvarez-Vázquez, Miguel Muniz-Calvente and Pelayo Fernández
The purpose of this study is to review the existing fatigue and vibration-based structural health monitoring techniques and highlight the advantages of combining both approaches.
Abstract
Purpose
The purpose of this study is to review the existing fatigue and vibration-based structural health monitoring techniques and highlight the advantages of combining both approaches.
Design/methodology/approach
Fatigue monitoring requires a fatigue model of the material, the stresses at specific points of the structure, a cycle counting technique and a fatigue damage criterion. Firstly, this paper reviews existing structural health monitoring (SHM) techniques, addresses their principal classifications and presents the main characteristics of each technique, with a particular emphasis on modal-based methodologies. Automated modal analysis, damage detection and localisation techniques are also reviewed. Fatigue monitoring is an SHM technique which evaluate the structural fatigue damage in real time. Stress estimation techniques and damage accumulation models based on the S-N field and the Miner rule are also reviewed in this paper.
Findings
A vast amount of research has been carried out in the field of SHM. The literature about fatigue calculation, fatigue testing, fatigue modelling and remaining fatigue life is also extensive. However, the number of publications related to monitor the fatigue process is scarce. A methodology to perform real-time structural fatigue monitoring, in both time and frequency domains, is presented.
Originality/value
Fatigue monitoring can be combined (applied simultaneously) with other vibration-based SHM techniques, which might significantly increase the reliability of the monitoring techniques.
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As the manufacturing industry is under pressure to face the global competition, it is necessary to improve productivity and reduce costs through minimization of wastage of…
Abstract
Purpose
As the manufacturing industry is under pressure to face the global competition, it is necessary to improve productivity and reduce costs through minimization of wastage of resources for their survival. This paper aims to present an analysis of the status of resource flexibility and lean manufacturing through conducting a case study in an Indian textile machinery manufacturing company and also demonstrate the various areas of future scope for improving lean manufacturing.
Design/methodology/approach
The case study has been conducted using the flexible system methodology (FSM) framework (Sushil, 1994). For measuring resource (labour and machine) flexibility and lean manufacturing, various factors contributing towards labour flexibility, machine flexibility and lean manufacturing are identified. To determine their relative weights, an analytical hierarchy process (AHP) has been used. A specially designed questionnaire is used to collect the information during case study on different aspects of resource flexibility and lean manufacturing. SAP-LAP analysis has also been carried out to look in to the ways the company is building up resource flexibility and lean manufacturing.
Findings
The status of labour flexibility, machine flexibility and lean manufacturing is merely 49.30, 47.10 and 47.40 per cent, respectively. The most important factors of labour flexibility and machine flexibility attained a value of 59.50 and 61.17 per cent, respectively. Similarly, only 39.09 per cent wastes are eliminated through lean manufacturing. There is a huge scope to achieve a higher degree of lean manufacturing through focusing on continuous improvement, just in time (JIT) and resource flexibility factors.
Research limitations/implications
The present study includes only labour and machines to compute the resource flexibility. Other resources may also be included to compute the overall resource flexibility.
Practical implications
The present study provides guidelines to analyze the status of resource flexibility and lean manufacturing. According to conclusions, frail areas in the manufacturing system can be identified and a suitable course of action could be planned for the improvement. Hopefully, this study will help the firm’s management to identify the problems to manage resource flexibility and implement an effective lean manufacturing.
Originality/value
In this work, the theoretical perspective has been used not only to update the original instrument, but also to study the subject from a perspective beyond that usually associated with resource flexibility and lean manufacturing.