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1 – 10 of over 9000Jiahe Wang, Huajian Li, Chengxian Ma, Chaoxun Cai, Zhonglai Yi and Jiaxuan Wang
This study aims to analyze the factors, evaluation techniques of the durability of existing railway engineering.
Abstract
Purpose
This study aims to analyze the factors, evaluation techniques of the durability of existing railway engineering.
Design/methodology/approach
China has built a railway network of over 150,000 km. Ensuring the safety of the existing railway engineering is of great significance for maintaining normal railway operation order. However, railway engineering is a strip structure that crosses multiple complex environments. And railway engineering will withstand high-frequency impact loads from trains. The above factors have led to differences in the deterioration characteristics and maintenance strategies of railway engineering compared to conventional concrete structures. Therefore, it is very important to analyze the key factors that affect the durability of railway structures and propose technologies for durability evaluation.
Findings
The factors that affect the durability and reliability of railway engineering are mainly divided into three categories: material factors, environmental factors and load factors. Among them, material factors also include influencing factors, such as raw materials, mix proportions and so on. Environmental factors vary depending on the service environment of railway engineering, and the durability and deterioration of concrete have different failure mechanisms. Load factors include static load and train dynamic load. The on-site rapid detection methods for five common diseases in railway engineering are also proposed in this paper. These methods can quickly evaluate the durability of existing railway engineering concrete.
Originality/value
The research can provide some new evaluation techniques and methods for the durability of existing railway engineering.
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Ayoub Abou Houraira, Abdellah Ouali, Ouafa Elhammoumi and Ahmed Fekri
Morocco is facing climate change, as shown by national studies conducted to date. The purpose of our research work is, on one hand, to develop an experimental protocol; simulating…
Abstract
Purpose
Morocco is facing climate change, as shown by national studies conducted to date. The purpose of our research work is, on one hand, to develop an experimental protocol; simulating the Moroccan climate, through exposing concretes to accelerated aging in different cycles of temperature variation (+5 to +40 C°) and humidity (60–98% RH) and on another hand, to determine the effect of exposure to temperature and humidity variation cycles on the durability indicators (of concrete [with and without thermal cure]).
Design/methodology/approach
For this purpose, three classes of concrete were studied (C35, C40 and C55). Each class of concrete was considered first with no addition of silica fume (SF) and then with a 10% addition of SF. The concrete samples underwent three types of conditioning before performing the tests. The control concretes (Ct) were demoulated after 24 h and stored under stable temperature and humidity conditions (20 ± 2 °C and 80% ± 5 RH). Treated concretes (CV) demouled after 24 h and exposed to 300 cycles of 12 h of temperature and moisture variation in a climate chamber. And finally, concretes that have undergone a heat cure (CTV) for 5 h at 90 °C, were then removed from the mold and exposed to temperature and moisture variations cycles identical to treated concrete (CV).
Findings
The results obtained show that aging accelerated by temperature change, and humidity improves durability indicators compared to Ct. Concretes that have undergone a thermal cure, followed by accelerated aging, show an improvement in durability indicators between 50 and 200 cycles, but the performance of concrete decreases after 200 exposure cycles. The addition of SF plays a beneficial role in the durability of concrete in the three exposure environments.
Originality/value
The originality of the work is, to develop an experimental protocol, simulating the Moroccan climate, through exposing concretes to accelerated aging in different cycles of temperature variation (+5 to +40 C°) and humidity (60–98% RH) and on another hand, to determine the effect of exposure to temperature and humidity variation cycles on the durability indicators of conventional concrete (with and without thermal cure).
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The consideration of alternative sources of material for construction is imperative to reduce the environmental impacts as two-fifths of the carbon footprint of materials is…
Abstract
The consideration of alternative sources of material for construction is imperative to reduce the environmental impacts as two-fifths of the carbon footprint of materials is attributed to the construction industry. One alternative material with improved biodegradable attributes which can contribute to carbon offset is bamboo. The commercialisation of bamboo in modern infrastructures has significant potential to address few of the Sustainable Development Goals (SDGs) itemised by the United Nations, namely SDG 9 about industry, innovation and infrastructure. Other SDGs covering sustainable cities and communities, responsible consumption and production and climate action are also indirectly addressed when utilising sustainable construction materials. Being a natural material however, the full commercialisation of materials such as bamboo is constrained by a lack of durability. Besides fracture mechanisms arising from load-induced cracks and thermal modification, the durability of bamboo material is greatly impaired by biotic and abiotic factors, which equally affect its natural rate of degradation, hence fracture behaviour. In first instance, this chapter outlines the various factors leading to the durability limitations in bamboo material due to load-induced cracks and natural degradation based on recent findings in this field from the author's own work and from past literature. Secondly, part of this chapter is devoted to a new approach of processing the surge of information about the varied aspects of bamboo durability by considering the powerful technique of artificial intelligence (AI), specifically the artificial neural network (ANN) for prediction modelling. Further use of AI-enabled technologies could have an impactful outcome on the life cycle assessment of bamboo-based structures to address the growing challenges outlined by the United Nations.
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Eunice Y. Rhee, Jade Y. Lo, Mark T. Kennedy and Peer C. Fiss
Drawing on the notion of imprinting, we develop a framework for understanding category emergence and durability by suggesting that the durability of a category reflects its…
Abstract
Drawing on the notion of imprinting, we develop a framework for understanding category emergence and durability by suggesting that the durability of a category reflects its emergence conditions. We propose four ideal-typical mechanisms – consensus, proof, fiat, and truce – that arise from differences in the degree of agreement and the centralization of the authority regarding category definitions. Our framework not only relates category durability to emergence but also highlights the role of category promoters and constituencies in an ongoing process of category maintenance. We discuss implications for understanding the dynamics of the categorization process in various social and product market contexts.
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The purpose of this paper is to discuss a method that can evaluate the friction durability of automatic transmission fluid.
Abstract
Purpose
The purpose of this paper is to discuss a method that can evaluate the friction durability of automatic transmission fluid.
Design/methodology/approach
A small clutch was used to test the friction durability. The method adopts a similar sequence to that of SAE No. 2. Three commercial oils were studied. One of them meets the specification of the GM's DEXRONIIE and the others meet the DEXRONIII.
Findings
The results showed that two commercial oils have different friction durability. Two further samples were blended in the lab and friction durability was researched by this method.
Originality/value
The results showed that the samples have a good durability. The research indicates that the method is quite capable of distinguishing between some samples. The results also indicate the difference between the DEXRON specifications at friction durability.
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Yajun Ma, Wancheng Zhao, Shenghua Li, Yuansheng Jin, Yucong Wang and Tung C. Simon
Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine…
Abstract
Purpose
Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine oils.
Design/methodology/approach
The lubricating durability D was defined based on definition of three characteristic points Pd, PS, Pi and three key time lengths Td, Ts, Ti. Two kinds of engine oils, respectively, belonging to GF‐2 and GF‐3 categories, were selected as samples to compare their lubricating durability.
Findings
Test results indicate the GF‐3 oil has much better lubricating durability than GF‐2 oil. With investigation of the topography and chemical composition changes of wear tracks along with the tribotests' time extending, the meanings of three characteristic points were discussed. Analysis indicates much better tribofilm, formed by the synergistic effect of Ca‐containing detergent with MoDTC/ZDTP in GF‐3 oil, is the major factor resulting in GF‐3 oil's longer lubricating durability.
Originality/value
Provides further research on lubricating durability, which is important for engine oil change and maintenance, as well as decreased cost and pollution to the environment, and improved energy conservation.
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Haitao Zhang, Junfeng Sun and Mingyang Gong
The purpose of this study is to compare and analyze the anti-aging durability of asphalt and asphalt mixture under the conditions of inherent and improved performance. The…
Abstract
Purpose
The purpose of this study is to compare and analyze the anti-aging durability of asphalt and asphalt mixture under the conditions of inherent and improved performance. The research contents include: the mechanical properties (dynamic stability, bending strain, freeze-thaw splitting tensile strength ratio (TSR)) of different modified asphalt mixtures were tested by using the best modified asphalt.
Design/methodology/approach
The anti-aging durability of different modified asphalt was analyzed by using the results of macro tests such as penetration and softening point as evaluation indexes. Meanwhile, the change of the asphalt colloid instability index (Ic) in the aging process was used as the evaluation index to verify the results of the macroscopic test, and the best modified asphalt was obtained. On this basis, the composition of different modified asphalt mixtures was designed by using the best modified asphalt. Meanwhile, water stability was used as evaluation indexes to study the anti-aging durability of different modified asphalt mixtures.
Findings
The results show that styrene-butadiene-styrene (SBS) modified asphalt has better aging resistance. Due to the special storage time, the performance of rubber asphalt is also the best. Meanwhile, in terms of modified asphalt mixture, its high temperature performance and durability of anti-aging is as follows: 4% SBS /16% rubber modified asphalt mixture (IV) > 4% SBS modified asphalt mixture (II) > asphalt mixture (90#) (I) > 16% rubber modified asphalt mixture (III). The low temperature performance and durability of anti-aging is as follows: Ⅱ > IV > Ⅰ > Ⅲ. The water stability performance and durability of anti-aging is as follows: IV > Ⅲ > Ⅱ > Ⅰ.
Originality/value
The research results have important theoretical and guiding significance for exploring the change of intrinsic properties and improved properties of asphalt and asphalt mixture in the aging process and revealing the anti-aging mechanism of different modified asphalt mixtures.
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Salvinder Singh and Shahrum Abdullah
The purpose of this paper is to present the durability analysis in predicting the reliability life cycle for an automobile crankshaft under random stress load using the stochastic…
Abstract
Purpose
The purpose of this paper is to present the durability analysis in predicting the reliability life cycle for an automobile crankshaft under random stress load using the stochastic process. Due to the limitations associated with the actual loading history obtained from the experimental analysis or due to the sensitivity of the strain gauge, the fatigue reliability life cycle assessment has lower accuracy and efficiency for fatigue life prediction.
Design/methodology/approach
The proposed Markov process embeds the actual maximum and minimum stresses by a continuous updating process for stress load history data. This is to reduce the large credible intervals and missing loading points used for fatigue life prediction. With the reduction and missing loading intervals, the accuracy of fatigue life prediction for the crankshaft was validated using the statistical correlation properties.
Findings
It was observed that fatigue reliability corresponded well by reporting the accuracy of 95–98 per cent with a mean squared error of 1.5–3 per cent for durability and mean cycle to failure. Hence, the proposed fatigue reliability assessment provides an accurate, efficient, fast and cost-effective durability analysis in contrast to costly and lengthy experimental techniques.
Research limitations/implications
An important implication of this study is durability-based life cycle assessment by developing the reliability and hazard rate index under random stress loading using the stochastic technique in modeling for improving the sensitivity of the strain gauge.
Practical implications
The durability analysis is one of the fundamental attributes for the safe operation of any component, especially in the automotive industry. Focusing on safety, structural health monitoring aims at the quantification of the probability of failure under mixed mode loading. In practice, diverse types of protective barriers are placed as safeguards from the hazard posed by the system operation.
Social implications
Durability analysis has the ability to deal with the longevity and dependability of parts, products and systems in any industry. More poignantly, it is about controlling risk whereby engineering incorporates a wide variety of analytical techniques designed to help engineers understand the failure modes and patterns of these parts, products and systems. This would enable the automotive industry to improve design and increase the life cycle with the durability assessment field focussing on product reliability and sustainability assurance.
Originality/value
The accuracy of the simulated fatigue life was statistically correlated with a 95 per cent boundary condition towards the actual fatigue through the validation process using finite element analysis. Furthermore, the embedded Markov process has high accuracy in generating synthetic load history for the fatigue life cycle assessment. More importantly, the fatigue reliability life cycle assessment can be performed with high accuracy and efficiency in assessing the integrity of the component regarding structural integrity.
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Xiaoli Kong, Bo Zhou, Jixiao Wang and Wenping Li
The purpose of this paper is to study the engineering application of diamond like carbon (DLC) coatings on the surfaces of piston pins and bucket tappets for a 2.0 L supercharged…
Abstract
Purpose
The purpose of this paper is to study the engineering application of diamond like carbon (DLC) coatings on the surfaces of piston pins and bucket tappets for a 2.0 L supercharged gasoline engine. The friction loss and durability of DLC-coated components were investigated.
Design/methodology/approach
The tribological characteristics were examined under oil-lubricated conditions in a CETR UMT reciprocating tribometer. In a motored engine test rig, friction loss torque test was performed to estimate the improvement in fuel economy. Fired engine durability bench tests of typical duration of 450 h were completed to access the durability and wear resistance of DLC coating. Before and after durability tests, coated and uncoated components were measured on the sliding surface by a profilometer technique.
Findings
Friction and wear test results show that DLC coating has low friction coefficient and reduces the wear rates by almost ten times compared to those of uncoated surfaces. Friction loss measurements indicate that DLC-coated tappets can reduce valve train friction loss by 29 per cent, and DLC-coated piston pins can reduce piston group friction by 11 per cent. Based on fired engine durability bench tests, it is evidenced that none of the coated tappets and pins show any noticeable peeling or delamination. Wear profiles analysis results indicate that DLC-coated engine components give rise to a substantial reduction in wear.
Originality/value
DLC coating applied onto the working surface of piston pin and bucket tappet can effectively reduce the friction loss of gasoline engine. DLC coating exhibits sufficient durability and improves friction and wear performance.
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Visar Hoxha, Tore Haugen and Svein Bjorberg
The purpose of this paper is to develop the empirically tested framework about the knowledge and perception about sustainability of building materials in Prishtina, Kosovo from…
Abstract
Purpose
The purpose of this paper is to develop the empirically tested framework about the knowledge and perception about sustainability of building materials in Prishtina, Kosovo from the perspective of users, construction industry and facility managers.
Design/methodology/approach
A survey of representative sections of the population was designed and carried out in the capital city of Kosovo to determine the knowledge and perception of the population about the sustainability of building materials and to determine the main criteria of selection of sustainable building materials. The study may be used as guidelines for sustainable real estate developers in Prishtina during the materials selection process. Qualitative interviews were conducted with architects, consulting engineering companies, construction companies and facility managers from the region of Prishtina with open-ended questions also being used.
Findings
Results of quantitative research find that embodied energy, durability and low energy consumption are used as key criteria that influence the materials selection process on the part of users. The results of the cross-case analysis of qualitative measure the perceptions of construction industry and facility managers, according to which durability to a large degree is the main criterion for selection of sustainable building materials followed by embodied energy and low energy consumption.
Research limitations/implications
The study of measurement of level of knowledge and perception about sustainability of building materials in Kosovo focuses only on one pilot city; hence, further research is needed throughout Kosovo to validate the empirically tested tool within other geographical settings in Kosovo.
Originality/value
This survey represents the first quantification of knowledge and perception regarding the sustainability of building materials among users, construction sector and facility managers.
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