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- Xiao, Tian, et al.
(författare)
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Numerical study of heat transfer and load-bearing performances of corrugated sandwich structure with open-cell metal foam
- 2023
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Ingår i: International Journal of Heat and Mass Transfer. - 0017-9310. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Critical engineering applications require lightweight components that can effectively dissipate heat and provide sufficient load-bearing capacity. Examples of such applications include the jet blast deflector (JBD) on an aircraft carrier and engine combustion chambers in supersonic vehicles. While lightweight corrugated sandwich structures (CSSs) exhibit excellent load-bearing capacity, their heat transfer capacity falls short. To overcome this limitation, a strategy of filling the CSS with an open-cell metal foam (MF) is proposed to create a sandwich structure with ultralight load bearing and heat transfer capabilities. Numerical simulations were conducted to study the heat transfer and load-bearing performance of this new structure. The findings indicate that the use of a MF significantly improves the heat transfer capabilities of the CSS. Compared to the CSS, the Nusselt number of MF and CSS-foam composite at a Reynolds number of 240 were enhanced by 51.3% and 102.3%, respectively. The overall thermal performance of CSS-foam composites was optimized under the same pumping power constraints. In turbulent conditions, the overall thermal performance of CSS-foam composites was 5.9% to 55.4% higher than that of CSS in turbulent conditions. Furthermore, the simulations showed that when the CSS was subjected to static and quasi-static compression, the maximum von Mises stress occurred at the connection between the panel and the web.
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| 2. |
- Ahmed, Abubeker W, 1981-, et al.
(författare)
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Pavement performance follow-up and evaluation of polymer-modified test sections
- 2019
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Ingår i: The international journal of pavement engineering. - : Taylor and Francis Ltd.. - 1029-8436 .- 1477-268X. ; 20:12, s. 1474-1487
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Tidskriftsartikel (refereegranskat)abstract
- Between 2003 and 2006, a test road consisting of several conventional and polymer-modified structures was built on a motorway. Different combinations of styrene–butadiene–styrene (SBS) and ethyl vinyl acetate (EVA) polymer-modified binders were used. The test structures have been in service since then and have been monitored for over 9 years. The resistance of the different types of asphalt concrete mixes to rutting and cracking was measured and predicted. The impact of ageing on the mixes was also evaluated. Although all the sections are in good condition after 9 years of traffic, the predicted differences between the test sections based on the PEDRO (Permanent Deformation of asphalt concrete layers for Roads) approach and laboratory evaluations are noticeable. Lateral wander and transverse profile measurements indicated that studded winter tyre wear contributed to most of the rutting compared to permanent deformation due to heavy traffic. The unmodified mixes exhibited considerable ageing and the SBS-modified mixes were least affected by ageing. Furthermore, the SBS-modified base mix produced significantly better fatigue resistance than the conventional base mix. However, further investigations of the relationships between bitumen and mix properties and further follow-ups of the test sections are recommended to validate the findings.
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| 3. |
- Farcas, Florentina Angela
(författare)
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Evaluation of Asphalt Field Cores with Simple Performance Tester and X-ray Computed Tomography
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The importance of aggregate structure and air voids distribution for asphalt mixture rutting and cracking performance has been well established on the basis of experience and is well documented in the literature. Past and current investigations are limited to assessment of performance based on macroscopic behavior due to the difficulty associated with the quantitative measurement and analysis of the internal structure of asphalt mixtures. Lately, technical advances in X-ray Computed Tomography (CT) and image processing and analysis has made possible to bring the attention also to the internal structure of asphalt mixtures. SPT results from asphalt field cores, including dynamic modulus (before and after loading) and microstrain accumulation (flow number), exhibited significant variability; most likely, induced by irregularities in the core shape. The analysis of aggregate structure and air voids distribution performed trough X-ray CT, clearly identified segregation in the asphalt mixture as a key factor that induced variability in SPT results.
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| 4. |
- Hu, Rukun, et al.
(författare)
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Design and assessment on a bottom-cut shape for latent heat storage tank filled with metal foam
- 2024
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Ingår i: International Journal of Thermal Sciences. - 1290-0729. ; 197
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Tidskriftsartikel (refereegranskat)abstract
- The utilization of phase change materials (PCMs) holds tremendous potential of heat storage domain. The PCM's refractory at the latent heat thermal energy storage (LHTES) unit bottom hinders the heat storage efficiency, despite the significant improvement in thermal conductivity achieved through the addition of metal foam. This study employs numerical simulation to examine the impact of applying bottom cross-cut on PCM's spatial distribution in a horizontal LHTES unit. The manuscript analyzes parameters including melting fraction, complete melting time, Rayleigh number, natural convection heat transfer gain, melting phase interface, velocity and temperature distributions, and heat storage. The findings indicate that the proximity to the heating tube results in a reduction of solid volume at the LHTES unit bottom. A 0.6 bottom cross-cut ratio leads to an 18.84 % faster heat storage rate compared to a concentric-circle unit. Furthermore, a bottom cross-cut ratio of 0.5 enhances natural convection heat transfer gain by 3.28 times.
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| 10. |
- Jelagin, Denis, Docent, 1979-, et al.
(författare)
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Asphalt layer rutting performance prediction tools
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Flexible pavement rutting due to permanent deformation accumulation in asphalt layers is one of the most common modes of road failures. In addition to creating high maintenance costs, rutting is a major concern for traffic safety, as the rut development increases the risk of hydroplaning and introduce difficulties in vehicle steering. In this context, accurate methodologies for pavement rutting performance prediction are crucial for decision support in pavement design and rehabilitation. In particular, better rutting performance models are needed to evaluate, new asphalt materials as well as to evaluate the impact of different vehicle types on roads’ service life.The main goal of this report is to present a summary of the existing asphalt rutting performance prediction tools. The present review is limited to available and/or frequently referred to tests and models with an established link to field rutting performance. Accordingly, models focusing solely on permanent deformation on the material level are beyond the framework of the present study.Road structure and its materials, heavy vehicle parameters and climate affecting rutting accumulation in the field are identified. Their significance has been evaluated based on the experimental and numerical findings reported in the literature. Several rutting performance prediction models recently proposed in the literature are summarized along with the material characterization tests used in the models. The reviewed models’ capability to quantify the influence of various structural, material and traffic parameters on the pavement’s rutting performance is examined.It is concluded that implementation of rutting performance models incorporating experimentally measured viscoelastic and permanent deformation properties of asphalt mixtures is a promising way to improve the accuracy of pavement performance predictions. In particular since they allow the effect of novel materials, e.g. polymer-modified, on the pavement’s rutting performance to be quantified.
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