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Article
Publication date: 8 March 2011

Sudipto Ray and S.K. Roy Chowdhury

Although dependence of contact surface temperatures between rough sliding bodies on surface topography is more explicitly described in terms of three‐dimensional (3D) topographic…

683

Abstract

Purpose

Although dependence of contact surface temperatures between rough sliding bodies on surface topography is more explicitly described in terms of three‐dimensional (3D) topographic parameters, no work has yet been reported on this aspect. The paper seeks to carry out experiments to systematically correlate the 3D surface parameters to the contact temperature rise.

Design/methodology/approach

The surface temperatures at the contact between a relatively smooth zinc sulphide pin held against a rotating mild steel disc of varying surface topography were measured using an infrared thermal imaging system under different load and sliding velocity conditions. The main objective was to study the effect of 3D surface roughness parameters on the contact temperature rise.

Findings

The results indicate a rise in maximum contact temperature with the increase in a number of 3D parameters, such as, average surface roughness Sa, ten‐point height parameter Sz, skewness of the surface height distribution Ssk, mean summit curvature Ssc, and developed interfacial area ratio parameter Sdr while temperature was found to decrease with increasing values of another set of parameters, such as, kurtosis of the 3D surface texture Sku, summit density of the surface Sds, surface bearing index Sbi, core fluid retention index Sci, valley fluid retention index Svi, and root mean square slope of the surface Sdq.

Practical implications

In any sliding system, with mixed or boundary lubricated conditions, it can be attempted to find the optimum value of the roughness parameters so that on suitable processing of the surfaces a lower contact temperature rise can be achieved.

Originality/value

No work has yet been reported on the effect of 3D roughness parameters on contact temperature.

Details

Industrial Lubrication and Tribology, vol. 63 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 August 2011

Sudipto Ray and S.K. Roy Chowdhury

The paper's aim is to predict numerically the contact temperatures between two rough sliding bodies and to compare with the experimental results.

767

Abstract

Purpose

The paper's aim is to predict numerically the contact temperatures between two rough sliding bodies and to compare with the experimental results.

Design/methodology/approach

An elastic contact algorithm is used to analyze the normal contact between two nominally smooth surfaces. The algorithm evaluates real contact area using digitized roughness data and the corresponding contact pressure distribution. Using finite element method a steady state 3D temperature distribution at the interface between the sliding bodies is obtained. Using infrared (IR) imaging technique, experiments were carried out to measure the contact temperature distribution between rough rubbing bodies with a systematic variation of surface roughness and operating variables.

Findings

Contact temperature distributions over a wide range of normal load, sliding velocity and surface roughness have been obtained. It was seen that the maximum contact temperature expectedly increases with surface roughness (Sa values), normal load and sliding velocity. The results also indicate that the “hot spots” are located exactly at the positions where the contact pressures are extremely high. Temperatures can be seen to fall drastically at areas where no asperity contacts were established. The temperature contours at different depths were also plotted and it was observed that the temperatures fall away from the actual contact zone and relatively high temperatures persist at the “hot spot” zones much below the contact surface. Finally it is encouraging to find a good correlation between the numerical and experimental results and this indicates the strength of the present analysis.

Research limitations/implications

Experimental accuracy can be improved by using a thermal imaging camera that measures emissivity in situ and uses it to find the contact temperature. The spatial resolution and the response time of the camera also need to be improved. This can improve the correlation between numerical and experimental results.

Practical implications

One of the major factors attributed to the failure of sliding components is the frictional heating and the resulting flash temperatures at the sliding interface. However, it is not easy to measure such temperatures owing to the inherent difficulties in accessing the contact zone. Besides, thermal imaging techniques can be applied only with such tribo‐pairs where at least one of the contacting materials is transparent to IR radiation. In practice, such cases are a rarity. However, the good correlation observed between the numerical and experimental results in this work would give the practicing engineer a confidence to apply the numerical model directly and calculate contact temperatures for any tribo‐material pairs that are generally seen around.

Originality/value

A good correlation between the numerical and experimental results gives credence to the fact that the numerical model can be used to predict contact temperatures between any sliding tribo‐pairs.

Details

Industrial Lubrication and Tribology, vol. 63 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 4 March 2014

Yanzhong Wang, Bin Wei, Keyan Ning and Ming Han

This research investigated the mechanism of wet friction plates of engagement and solved the problem that the lock-up friction coefficient of sinter material could not be obtained…

277

Abstract

Purpose

This research investigated the mechanism of wet friction plates of engagement and solved the problem that the lock-up friction coefficient of sinter material could not be obtained but from experiments for a long time. The paper aims to discuss these issues.

Design/methodology/approach

Including four steps: surface topology sampling and reconstruction, fractal parameters obtaining and fractal surface simulating, micro-contact mechanics model and friction coefficient fractal model, and experimental verification.

Findings

After running in stage of the friction plates, the fractal dimension would reach a dynamically stable stage for a long time. The proportional coefficient K expresses the correlation between the base hardness and the asperities shear strength. The model could be property for one or more working condition via adjusting the coefficient K. The experiment data of friction coefficient are increased as the load magnified both in the model prediction and experiment practice. The trend is different from other models.

Originality/value

This research is original and it is supported by national defense project. It would be served for tracked vehicles to solve the defect in transmission system. The friction coefficient is obtained via solving the tangential force in MB model. The surface topography could be reconstructed by laser topography instrument and the parameters could be received by program.

Details

Industrial Lubrication and Tribology, vol. 66 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 13 March 2017

Wenjing Zhang, Wei Chen and Zhe Liu

The aim of this study is to understand thermal effects and surface topography of roller bearings with misaligned load under combination of multifactors by an experimental method.

179

Abstract

Purpose

The aim of this study is to understand thermal effects and surface topography of roller bearings with misaligned load under combination of multifactors by an experimental method.

Design/methodology/approach

A series of orthogonal experiments would need to be planned and performed. A ranking of impact degree of factors on edge effect and eccentric load effect can be learned with multivariate analysis of variance by Statistical Product and Service Solutions software. Influence rules of each individual factor can also be obtained through more experiments. A roller surface phase diagram both before and after test can be observed with metallographic microscope. An axial profile data of roller can be measured by PGI 3D Profiler, then a roller generatrix contour can be achieved through filtering measured signal with empirical mode decomposition method.

Findings

Slip fraction has most impact on edge effect, whereas tilting angle plays a key role in eccentric load effect. For the case of low temperature, skidding damage does not occur. Inversely, because of the high pressure in partial elastohydrodynamic lubrication caused by roller tilt, running-in occurs and micro asperity flattening is observed on a rough surface. And, the larger the tilting angle, the more obvious the micro-flattening and the greater the reduction of roller surface roughness after the test.

Originality/value

A lot of theoretical studies on thermal effect of roller bearings surface morphology have been published. However, there are little on relevant experimental study, especially on thermal effect with an integration of sliding, tilting and unbalance loading.

Details

Industrial Lubrication and Tribology, vol. 69 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 January 2017

Catalin Pirvu, Laura Maftei, Constantin Georgescu and Lorena Deleanu

This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the…

96

Abstract

Purpose

This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the composite is sliding on steel in dry contact.

Design/methodology/approach

There were mold disks with the following concentrations in glass beads: 2.5, 5.0, 10, 20, 30 and 50 per cent. The mix of glass beads has diameters in the range of several microns to 50 microns. Tests were done on a pin-on-disk tribotester, in dry regime, for the following parameters: average pressure (1, 2 and 3 MPa) and sliding speed (0.5, 1.0 and 1.5 m/s). Zones of 500 × 500 μm were investigated from worn tracks generated on the composite disks, and the average values of several 3D texture parameters were analyzed.

Findings

The authors plotted maps indicating no correlation between the glass bead concentration and the parameters characterizing the surface quality (amplitude parameters and functional parameters). Composites with concentrations of 10[…]30 per cent glass beads generated worn surfaces with better quality as compared to composites with extreme concentrations: low (2.5 and 5 per cent) and high (50 per cent).

Practical implications

This set of parameters allows for evaluating the influence of regime parameters on the surface quality, by comparing the obtained values before and after sliding, and this evolution of roughness parameters could give recommendations for selecting the friction couple of materials for particular contacts that function with repeated starts and stops.

Originality/value

The results encourage the researchers to use a set of 3D texture parameters instead of “classical” two-dimensional parameters, the arithmetic mean deviation of the profile, Ra, because this set of parameters better evaluate the surface quality, especially for worn surfaces.

Details

Industrial Lubrication and Tribology, vol. 69 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 August 2004

Ali Osman Kurban

This paper presents an investigation into the classical problem using an experimental apparatus and applying an artificial neural network (NN) optimisation approach for…

605

Abstract

This paper presents an investigation into the classical problem using an experimental apparatus and applying an artificial neural network (NN) optimisation approach for determining the pressure distribution in a journal bearing at elasto‐hydrodynamic state of lubrication. The experimental system is employed at different working speeds with different surface roughness of shafts for getting pressure distribution. A NN is employed to predict the real data of the system as an optimisation technique. The NN is a radial basis function back propagation network. The NN has a superior performance to follow the desired results of the system and is employed to analyse such systems parameters in practical applications.

Details

Industrial Lubrication and Tribology, vol. 56 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 24 December 2021

Mohammadsina Sharifi Ghalehnoei

The purpose of this study is to develop the performance model of buildings designed by the seismic code 2800 against the explosion wave and determination of safety distance.

62

Abstract

Purpose

The purpose of this study is to develop the performance model of buildings designed by the seismic code 2800 against the explosion wave and determination of safety distance.

Design/methodology/approach

Analytical models of three-, five- and ten story structures that used moment frame system and also a ten-storey building with shaer wall designed based on the seismic code 2800 in term of design and nonlinear analysis were generated for use with Perform-3D software. Extensive parametric analysis is executed on different explosive loads with 100, 500, 1,000 and 5,000 Trinitrotoluene, soil types 2 and 3, models eqs and eqbs, the number of story buildings and the effect of shear wall to determine the safety distance based on collapse threshold performance (CP) level criterion.

Findings

The results indicate that by increasing the explosives mass from 100 to 5,000 kg and the number of the stories three and five induce increasing the safety distance of CP level in buildings to 4.5 meter and 3 meter times, respectively. Ten-story structures modeled on shear wall show very good performance because of stiffness rising and high energy absorption. In addition, by increasing the stories from five to ten, the amount of the safety distance reduces the CP level to 3.9 meter times.

Originality/value

The results of this work are meaningful for explosion-resistant design and damage assessments of reinforced concrete moment framed structures subjected to explosive explosion.

Details

World Journal of Engineering, vol. 20 no. 3
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 28 October 2019

Jaideep Roy and Prabal Roy Chowdhury

In a global environment where terrorist organisations based in a poor country target a rich nation, this paper aims to study the properties of a dynamically incentive compatible…

126

Abstract

Purpose

In a global environment where terrorist organisations based in a poor country target a rich nation, this paper aims to study the properties of a dynamically incentive compatible contract designed by the target nation that involves joint counter-terror tasks with costly participation by each country. The counter-terror operations are however subject to ex post moral hazard, so that to incentivise counter-terror, the rich country supplies developmental aid. Development aid also helps avoid unrest arising from counter-terror activities in the target nation. However, aid itself can be diverted to non-developmental projects, generating a novel interlinked moral hazard problem spanning both tasks and rewards.

Design/methodology/approach

The authors use a dynamic model where the aid giving countries and aid receiving countries behave strategically. Then they solve for the sub game perfect Nash equilibrium of this game.

Findings

The authors characterise the optimal contract, showing that the dynamic structure of counter-terror resembles the shock-and-awe discussed by military strategists. The authors then prove that it is not necessarily the case that a more hawkish (resp. altruistic) donor is less pro-development (resp. softer on terror). In addition, the authors show that it may be easier to contract for higher counter-terror inputs when the recipient is more sympathetic to terrorists. The authors also discuss other problems faced by developing nations where this model can be readily adopted and the results can endorse appealing policy implications.

Originality/value

The authors characterise the optimal contract, showing that the dynamic structure of counter-terror resembles the shock-and-awe discussed by military strategists. It is proved that it is not necessarily the case that a more hawkish (resp. altruistic) donor is less pro-development (resp. softer on terror). In addition, the authors show that it may be easier to contract for higher counter-terror inputs when the recipient is more sympathetic to terrorists. Other problems faced by developing nations are also discussed where this model can be readily adopted, and the results can endorse appealing policy implications. These results have important policy implications, in particular in today’s world.

Details

Indian Growth and Development Review, vol. 13 no. 2
Type: Research Article
ISSN: 1753-8254

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Book part
Publication date: 30 October 2024

Md. Wasiul Islam, Md. Mahfuz Ur Rahman and Shakil Ahmed

Visits to locations connected to historical atrocities, tragedy, suffering, or presumably dreadful events are referred to as “dark tourism”. While Bangladesh may not be widely…

Abstract

Visits to locations connected to historical atrocities, tragedy, suffering, or presumably dreadful events are referred to as “dark tourism”. While Bangladesh may not be widely known for dark tourism, several unexplored avenues may be of interest to those who engage in this type of unique and unconventional tourism experience. In addition to creating job opportunities and income generation in Bangladesh, it can achieve educational objectives, communicate with a broad audience, raise awareness of events of the past, and quench people's thirst for information, which can help them to comprehend a society. Though Bangladesh has several somber locations connected to tragic events including World War II, liberation war sites, mass killing sites, shipbreaking yards, Rohingya refugee camps, riots, and the mother language movement, traditional tourism predominates there. If managed responsibly, these varied resources, somber locations, and histories, some of which date back to 1800, could make Bangladesh a dark tourism destination. Although dark tourism in Bangladesh has the potential to contribute to historical awareness, preservation, educational opportunities, and socioeconomic development, it is yet unexplored due to a lack of knowledge, experience, policy, effective marketing, and some controversies. By approaching responsibly, Bangladesh can leverage its history to attract visitors' interests in exploring the darker aspects of the country's past. Hence, this chapter is designed to explore the status and potential significance, prospects, and challenges of dark tourism in Bangladesh. The findings will help policymakers, tourists, and other stakeholders to explore and enjoy enormous benefits from Bangladesh's untapped dark tourism opportunities.

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Article
Publication date: 13 December 2022

Jimut Bahan Chakrabarty, Soumya Roy and Shovan Chowdhury

In order to reduce avoidably lengthy duration required to test highly reliable products under usage stress, accelerated life test sampling plans (ALTSPs) are employed. This paper…

214

Abstract

Purpose

In order to reduce avoidably lengthy duration required to test highly reliable products under usage stress, accelerated life test sampling plans (ALTSPs) are employed. This paper aims to build a decision model for obtaining optimal sampling plan under accelerated life test setting using Type-I hybrid censoring scheme for products covered under warranty.

Design/methodology/approach

The primary decision model proposed in this paper determines ALTSP by minimizing the relevant costs involved. To arrive at the decision model, the Fisher information matrix for Type-I hybrid censoring scheme under accelerated life test setting is derived. The optimal solution is attained by utilizing appropriate techniques following a nonlinear constrained optimization approach. As a special case, ALTSP for Type-I censoring is obtained using the same approach. ALTSP under Type-I hybrid censoring using the variance minimization approach is also derived.

Findings

On comparing the optimal results obtained using the above mentioned approaches, it is found that the cost minimization approach does better in reducing the total cost incurred. Results also show that the proposed ALTSP model under cost function setting has considerably lower expected testing time. Interesting findings from the sensitivity analysis conducted using a newly introduced failure dataset pertaining to locomotive controls are highlighted.

Originality/value

The research introduces a model to design optimum ALTSP for Type-I hybrid censoring scheme. The practical viability of the model makes it valuable for real-life situations. The practical application of the proposed model is exemplified using a real-life case.

Details

International Journal of Quality & Reliability Management, vol. 40 no. 7
Type: Research Article
ISSN: 0265-671X

Keywords

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