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Article
Publication date: 5 May 2015

Babruvahan Pandurang Ronge and Prashant Maruti Pawar

– This paper aims to focus on the stochastic analysis of composite rotor blades with matrix cracking in forward flight condition.

Abstract

Purpose

This paper aims to focus on the stochastic analysis of composite rotor blades with matrix cracking in forward flight condition.

Design/methodology/approach

The effect of matrix cracking and uncertainties are introduced to the aeroelastic analysis through the cross-sectional stiffness properties obtained using thin-walled beam formulation, which is based on a mixed force and a displacement method. Forward flight analysis is carried out using an aeroelastic analysis methodology developed for composite rotor blades based on the finite element method in space and time. The effects of matrix cracking are introduced through the changes in the extension, extension-bending and bending matrices of composites, whereas the effect of uncertainties are introduced through the stochastic properties obtained from previous experimental and analytical studies.

Findings

The stochastic behavior of helicopter hub loads, blade root forces and blade tip responses are obtained for different crack densities. Further, assuming the behavior of progressive damage in same beam is measurable as compared to its undamaged state, the stochastic behaviors of delta values of various measurements are studied. From the stochastic analysis of forward flight behavior of composite rotor blades at various matrix cracking levels, it is observed that the histograms of these behaviors get mixed due to uncertainties. This analysis brings out the parameters which can be used for effective prediction of matrix cracking level under various uncertainties.

Practical implications

The behavior is useful for the development of a realistic online matrix crack prediction system.

Originality/value

Instead of introducing the white noise in the simulated data for testing the robustness of damage prediction algorithm, a systematic approach is developed to model uncertainties along with damage in forward flight simulation.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 6 August 2010

Chetan S. Jarali and D. Roy Mahapatra

The purpose of this paper is to investigate the stress distribution in shape memory alloy (SMA) composite due to phase transformations in the fiber in view of the applied boundary…

Abstract

Purpose

The purpose of this paper is to investigate the stress distribution in shape memory alloy (SMA) composite due to phase transformations in the fiber in view of the applied boundary conditions on the matrix.

Design/methodology/approach

A consistent homogenization of a SMA wire‐reinforced polymer composite volume element undergoing quasi‐static deformation was performed and SMA wire‐matrix interface behaviour was presented. For the SMA wire, a one‐dimensional phenomenological constitutive model was used. Eshelby's inclusion theory was employed for homogenization. A strain averaging approach was reviewed in which the average strain was substituted back to obtain the expressions for the effective stiffness, the inelastic strain, and the average stresses in the constituent phases. In order to study the stress distribution in SMA composite and constituent phases (fiber and matrix) as a consequence of the SMA wire‐matrix interface effect, interfacial stress model was derived. Interfacial axial and shear stress distribution is characterized for forward and reverse phase transformations. Finally, the thermomechanical behaviours were computed by applying strain energy approach incorporating the interface effects.

Findings

The results presented show that due to the difference between the shear modulus of matrix and SMA wire, and because of the strain non‐uniformity at the SMA wire‐matrix interface, shear stress is developed within the matrix under the axial loading of the representative volume element (RVE). The shear stress increases more rapidly as the SMA wire radius is increased but not with increase in the length. However, the axial stress does not increase much with increase in the SMA wire radius and length. Further, the average stress equation of the RVE at the SMA wire‐matrix interface is effectively addressed. The modeling approach is successfully validated extensively for different geometric and volumetric parameters for different loading conditions. It is evident that the interface effect of SMA wire composites is SMA stiffness dominated due to the fact that the geometric parameters do not influence much the stresses as compared to the change in SMA wire stiffness.

Originality/value

The approach is based on modeling the fiber matrix interface effect using homogenization scheme. Further, the strain energy approach is applied to compute the stress‐strain response. This indicates the importance of modeling the SMA wire‐matrix interface effect, and in particular, the energy exchange between the constituent phases. The results have been compared for different geometric parameters as well as volume fractions of the constituent phases under different loading conditions.

Details

Multidiscipline Modeling in Materials and Structures, vol. 6 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 1 June 2000

R.V.N. Melnik

The dynamics of coupling between spectrum and resolvent under ε‐perturbations of operator and matrix spectra are studied both theoretically and numerically. The phenomenon of…

4157

Abstract

The dynamics of coupling between spectrum and resolvent under ε‐perturbations of operator and matrix spectra are studied both theoretically and numerically. The phenomenon of non‐trivial pseudospectra encountered in these dynamics is treated by relating information in the complex plane to the behaviour of operators and matrices. On a number of numerical results we show how an intrinsic blend of theory with symbolic and numerical computations can be used effectively for the analysis of spectral problems arising from engineering applications.

Details

Engineering Computations, vol. 17 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 31 May 2022

Dipankar Das

To run a job guarantee public policy scheme, it is important to know the aspiration level or the reference point of labor, and accordingly, the labor hour and the wage sequence…

Abstract

Purpose

To run a job guarantee public policy scheme, it is important to know the aspiration level or the reference point of labor, and accordingly, the labor hour and the wage sequence are to be prepared. The existing job guarantee schemes consider the same wage rates for all types of jobs. As a result, it is to identify the reference point. The present work aims to propose a job guarantee scheme where different types of jobs have different wage rates. The paper explains the choice problem between labor and leisure at different wage rates and proposes complete computational tools to be incorporated into the job guarantee schemes. The paper also gives a mechanism to prepare the list of jobs and corresponding wage rates by maintaining a balance between labor and leisure, where productive activities measure labor hours and labor welfare measures leisure hours. Lastly, the paper provides the analytical tools to interpret the ex-post data of the job guarantee public policy schemes.

Design/methodology/approach

The paper has been written based on the Coordination Game and its Welfare Implications in the job guarantee public policy schemes.

Findings

The present paper gives an initial work to measure the choice between labor and leisure for the different wage rates practically. This will help in getting the equilibrium strategies, namely, the combination of the labor hour and the wage rate between the policymaker and the labor. This method will help to implement the job guarantee schemes. For example, to run successfully the Basic Income policy, the basic income calculation should give due care; otherwise, there will be a downward trend in the basic income and the welfare of labor will be reduced, because the labor would have to supply excess labor to meet the target income.

Originality/value

This paper derives theories and explains how the equilibrium in this coordination game can be achieved. The paper explains how the policy of the job guarantee schemes can be practiced practically. In the MGNREGA scheme, the public institution declares different categories of jobs with different wage rates. The categories have been classified with respect to the hours required to complete the job. Therefore, the public institution declares different lists or a sequence of pairs of labor hours and wage rates. Moreover, the list is stochastic, because the list can be changed by the inclusion of an offer from the market as well. The labor has to select from the list. The challenge on the part of the public institution is to prepare the list in such a way so that the inclusion of the market offers will not distort the equilibrium of the coordination game. An important method has been proposed here to analyze the ex-post data of job offers so that the preparation of the future sequence of the job offers can be prepared with due care. One objective of the policymaker here is to make a list of job offers in such a way so that the labor supply will be converging to a point and that will not deviate if the wage rate increases further. This objective will make a balance of the distribution of funds between the existing registered labor and the new entrants into the job guarantee schemes.

Details

Journal of Economic Studies, vol. 50 no. 4
Type: Research Article
ISSN: 0144-3585

Keywords

Article
Publication date: 27 January 2020

Ankang Liu, Bing Wang and Fei Li

This paper aims to study the effect of elevated temperature on the compression behaviour of carbon fibre polyphenylene sulphide (CF/PPS) laminates notched and unnotched specimens…

Abstract

Purpose

This paper aims to study the effect of elevated temperature on the compression behaviour of carbon fibre polyphenylene sulphide (CF/PPS) laminates notched and unnotched specimens made by film stacking method (FSM).

Design/methodology/approach

The surface of CF was coated with a silane coupling agent to form an effective transition layer with PPS, so as to enhance the interfacial interaction between CF and PPS. Considering the influence of fabrication pressure, forming temperature and cooling rate on the properties of laminates to obtain a reasonable preparation process. Conducting a compressive experiment of notched and unnotched specimens at different temperatures, which failure modes were examined by scanning electron microscope and stereo microscope.

Findings

The experimental observations highlight that with the increase of temperature, the transition failure mode from fibre broken to kink-band appeared in unnotched specimens, which were closely attributed to the matrix state. The notched specimens appeared more complex failure mode, which can be attributed to the joint effect of temperature and opening hole.

Research implications

A simple way of FSM for composite material laminates has been developed by using woven CF and PPS films.

Originality/value

The outcome of this study will help to understand the compression response mechanism of composite materials made by FSM at different temperature.

Details

Pigment & Resin Technology, vol. 50 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 February 2000

Antony Beckett, Paul Hewer and Barry Howcroft

Deregulation and the emergence of new forms of technology have created highly competitive market conditions which have had a critical impact upon consumer behaviour. Bank…

14371

Abstract

Deregulation and the emergence of new forms of technology have created highly competitive market conditions which have had a critical impact upon consumer behaviour. Bank providers must, therefore, attempt to better understand their customers in an attempt not only to anticipate but also to influence and determine consumer buying behaviour. The paper accordingly presents and develops a model which attempts to articulate and classify consumer behaviour in the purchasing of financial products and services. The theoretical insights generated by this model are then used to examine qualitative research data gained from focus group discussions on consumers’ attitudes to their financial providers and their financial products. Finally, these findings are examined for the potential insights they provide to bank providers attempting to identify appropriate strategies which are conducive to increased customer retention and profitability.

Details

International Journal of Bank Marketing, vol. 18 no. 1
Type: Research Article
ISSN: 0265-2323

Keywords

Article
Publication date: 5 May 2022

Russo Swart, Feras Korkees, Peter Dorrington and Joshua Thurman

Composites 3D printing has the potential to replace the conventional manufacturing processes for engineering applications because it allows for the manufacturing of complex shapes…

Abstract

Purpose

Composites 3D printing has the potential to replace the conventional manufacturing processes for engineering applications because it allows for the manufacturing of complex shapes with the possibility of reducing the manufacturing cost. This paper aims to analyse the performance of 3D printed fibre reinforced polymer composites to investigate the energy absorption capabilities and the residual properties before and after impact.

Design/methodology/approach

Various composites composed of carbon fibres and Kevlar fibres embedded into both Onyx and nylon matrix were printed using Markforged-Two 3D printers. Specimens with different fibre orientations and fibre volume fractions (Vf) were printed. A drop-weight impact test was performed at energies of 2, 5, 8 and 10 J. Flexural testing was performed to evaluate the flexural strength, flexural modulus and absorbed energy under bending (AEUB) before and after impact. Additionally, 3D printed carbon fibre composites were tested at two different temperatures to study their behaviour under room and sub-ambient temperatures. Failure modes were investigated using optical and high depth of field microscopes for all 3D printed composite samples.

Findings

Kevlar/nylon composites with a unidirectional lay-up and 50% Vf exhibited the most prominent results for AEUB at room temperature. The high-Vf carbon fibre composite showed the highest ultimate strength and modulus and performed best at both temperature regimes.

Originality/value

The work, findings and testing produced in this paper are entirely original with the objective to provide further understanding of 3D printed composites and its potential for use in many applications.

Details

Rapid Prototyping Journal, vol. 28 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 April 1978

HÅKAN ANDERSSON

The theory of relatively closed systems first appeared in Kybernetes as two consecutive papers by Grubbström This work was a development of studies in cybernetic modelling…

Abstract

The theory of relatively closed systems first appeared in Kybernetes as two consecutive papers by Grubbström This work was a development of studies in cybernetic modelling performed by Lange and Klir and Valach. This paper deals with an application taken from the field of inventory control. The purpose is to show how the theory of relatively closed systems can be used to formulate models, analyse stability conditions and compute equilibrium values for the variables involved.

Details

Kybernetes, vol. 7 no. 4
Type: Research Article
ISSN: 0368-492X

Article
Publication date: 8 May 2017

Yong Liu and Kevin W. Li

The purpose of this paper is to propose a novel prospect-based two-sided matching decision model for matching supply and demand of technological knowledge assisted by a broker…

Abstract

Purpose

The purpose of this paper is to propose a novel prospect-based two-sided matching decision model for matching supply and demand of technological knowledge assisted by a broker. This model enables the analyst to account for the stakeholders’ psychological behaviours and their impact on the matching decision in an open innovation setting.

Design/methodology/approach

The prospect theory and grey relational analysis are used to develop the proposed two-sided matching decision framework.

Findings

By properly calibrating model parameters, the case study demonstrates that the proposed approach can be applied to real-world technological knowledge trading in a market for technology (MFT) and yields matching results that are more consistent with the reality.

Research limitations/implications

The proposed model does not differentiate the types of knowledge exchanged (established vs novel, tacit vs codified, general vs specialized) (Ardito et al., 2016, Nielsen and Nielsen, 2009). Moreover, the model focuses on incorporating psychological behaviour of the MFT participants and does not consider their other characteristics.

Practical implications

The proposed model can be applied to achieve a better matching between technological knowledge suppliers and users in a broker-assisted MFT.

Social implications

A better matching between technological knowledge suppliers and users can enhance the success of open innovation, thereby contributing to the betterment of the society.

Originality/value

This paper furnishes a novel theoretical model for matching supply and demand in a broker-assisted MFT. Methodologically, the proposed model can effectively capture market participants’ psychological considerations.

Details

Journal of Knowledge Management, vol. 21 no. 3
Type: Research Article
ISSN: 1367-3270

Keywords

Article
Publication date: 1 June 1993

Carol A. O′Connor

Seeks to help managers to recognize different types of resistanceand how to react to them. Categorizes types of resistance (resistancequadrants) and presents questions to help…

4882

Abstract

Seeks to help managers to recognize different types of resistance and how to react to them. Categorizes types of resistance (resistance quadrants) and presents questions to help identify the personality of the resistor. Resistance to change can be intentional or unintentional, covert or overt. Describes causes of resistance and presents diagnostic questions. Managers with self‐awareness and a sense of humour are most successful in overcoming resistance to change.

Details

Leadership & Organization Development Journal, vol. 14 no. 6
Type: Research Article
ISSN: 0143-7739

Keywords

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