http://bura.brunel.ac.uk/handle/2438/8625 Mon, 06 Apr 2026 12:32:44 GMT 2026-04-06T12:32:44Z http://bura.brunel.ac.uk/handle/2438/33105 Title: Study on the mechanical state of inner surface crack tips at SA508-52M-316L dissimilar metal welded joint interfaces Authors: Wang, S; Li, Y; Wang, B; Li, W; Cui, L; Wu, G; Anguilano, L; Xue, H Abstract: Low alloy steel SA508 welded to type 316L austenitic stainless steel using nickel-based filler materials, such as alloy 52M, represents one of the most frequently employed configurations of dissimilar metal welded joints (DMWJs) within the primary circuit of a pressurized water reactor (PWR). In response to the issue of structural integrity assessment of DMWJs at the primary circuit safe-end, a three-dimensional full-size finite element model considering the material property gradient was established. The mechanical response characteristics of inner surface crack tips under the coupling effects of complex loading and mechanical heterogeneity were systematically analyzed. By integrating sub-modeling techniques with the predefined field method, a multiscale correlation analysis between the global mechanical behavior of the full-size structure and the local stress–strain fields at crack tips was conducted. The influences of crack location on stress triaxiality and plastic strain distribution at crack tips were specifically investigated. A comparative analysis reveals that the conventional sandwich model underestimates crack-tip peak opening stress by approximately 15% at the SA508-52Mb interface and by about 11% at the 52Mw-316L interface within their respective heat-affected zones (HAZs); corresponding crack-tip peak plastic strain (PEEQ) is overestimated by roughly 13% and 46%. Analysis shows that crack-tip opening stress and plastic strain exhibit higher values in the SA508 and 316L HAZs. Furthermore, cracks near structural discontinuities demonstrate more pronounced mechanical heterogeneity than those in flat regions. The proposed continuous transition model effectively addresses this limitation, providing a more accurate mechanical assessment for engineering applications. Description: Data availability: Data will be made available on request. Wed, 01 Apr 2026 00:00:00 GMT http://bura.brunel.ac.uk/handle/2438/33105 2026-04-01T00:00:00Z http://bura.brunel.ac.uk/handle/2438/33101 Title: A Passive Noise Attenuation Earplug Designed to Minimise Unwanted Air Turbine Driven High-Speed Dental Drill Noise Authors: Jiang, P; Atherton, MA; Mllar, BJ Abstract: Introduction: Air turbine dental drill noise contains high-frequency components that are of concern for patients and dental staff. Meanwhile, verbal communication between the dentist and patient is essential. Conventional active noise-cancelling headphones are ineffective for dental drill noise and simply suppress all sound and hinder communication. Method: A compact passive earplug device was designed specifically to attenuate broadband high-frequency noise ranges from 5 to 8 kHz employing an array of quarter wavelength (QW) resonators. This device was 3D printed and tested against white noise to enhance the objectivity of analysis, using a calibrated ear and cheek simulator to effectively measure its performance. Results: The results showed that the resonators produced an average reduction of 27 dB across the targeted frequency range. When compared with two proprietary passive earplugs, this developed passive device prototype was able to attenuate an average of 9 dB more across the target frequency range whilst delivering louder speech signals of 14 dB more. The results also show that using an array of resonators exhibits an accumulated effect of individual resonator performance. Conclusions: This low-cost passive device could have a place in the dental clinic to reduce unwanted drill noise equivalent to the white noise high frequency spectra tested. Description: Data Availability: All sound recordings used to support the findings of this study are available from the corresponding author upon request. Fri, 01 Sep 2023 00:00:00 GMT http://bura.brunel.ac.uk/handle/2438/33101 2023-09-01T00:00:00Z http://bura.brunel.ac.uk/handle/2438/33066 Title: Modelling hydrogen enriched ammonia combustion through laminar flame speed and mass fraction burn analysis Authors: Rrustemi, DN; Megaritis, T; Ganippa, LC Abstract: Ammonia is a promising zero-carbon fuel for internal combustion engines; however, its low laminar flame speed makes lean combustion highly sensitive to turbulence and flame development. In this study, an entrainment-based two-zone combustion model is developed for hydrogen-enriched ammonia spark-ignition engines. The novelty of the approach lies in calibrating turbulence-related correction coefficients to simulate the combustion phasing using hydrogen-enriched ammonia laminar flame speed values. The results show that hydrogen enrichment accelerates both the early flame development and flame propagation phases due to enhanced chemical reactivity, leading to improved indicated mean effective pressure compared to neat ammonia. For a given excess air ratio, peak IMEP is achieved at 10% hydrogen addition by volume. The developed two-zone combustion model also captured the effects of exhaust gas recirculation through reduced flame speed and changes in thermodynamic properties. At 20% exhaust gas recirculation, nitric oxide emissions decreased by 48%, while the indicated specific fuel consumption increased by 10%. Description: Highlights: • Hydrogen improves performance of ammonia combustion. • NO emissions reduced by 48%, while ISFC increased by 10% with 20% EGR addition. • N2O emissions decreased with hydrogen enrichment. • A time efficient two-zone model for ammonia and hydrogen mixture was developed.; Data availability: Data will be made available on request. Wed, 18 Mar 2026 00:00:00 GMT http://bura.brunel.ac.uk/handle/2438/33066 2026-03-18T00:00:00Z http://bura.brunel.ac.uk/handle/2438/33065 Title: Dynamic programming model for a thermal energy storage-based heat recovery system in a process industry plant Authors: Castro Oliveira, M; Delpech, B; Alhajri, A; Jouhara, H; Montorsi, L; Filipe, RM; Matos, HA Abstract: Heat recovery systems (HRS) exist in conceptual configurations which encompass a set of energy-using processes installed on a particular site, a set of waste heat recovery technologies and all potential recirculation of material and energy streams with the overall aim to generate an overall benefit related to improvement in energy efficiency. A specific example of HRS are those that contain thermal energy storage (TES) components. In the context of the development of computational models, this type of HRS is modelled according to a dynamic simulation and optimisation perspective, owing to the transient state-based nature of these systems. This work presents the development and further analysis of an optimisation model developed according to the dynamic programming (DP) methodology for an HRS set to be implemented in a process industry plant. Such model was developed with the Modelica language, being an integral part of the ThermWatt simulation and optimisation tool. The developed model proved to be useful for the proposed objective of analysing transient state-based heat recovery systems, allowing an accurate modelling of the physical phenomena occurring during the time of operation of these systems. A relative reduction of 20.80% energy-related operational costs has been assessed for the system’s optimal configuration, which corresponds to a 0.51 M€/year absolute reduction (from 2.38 M€/year to 1.87 M€/year). This work is set to compensate for a knowledge gap related to the inexistence of studies approaching the use of mathematical programming methods for the dynamic (transient state-oriented) optimisation of thermal energy storage-based heat integration systems. Description: Highlights: • A Portuguese ceramic industry plant with four kilns was approached and analysed. • A heat recovery system with a thermal energy storage unit was conceptualized. • An dynamic programming model was developed for the conceptualized system. • The developed model was revealed to be robust with respect to the defined objective. • A significant 0.50 M€/year savings, for a 20.82% relative reduction, was assessed.; Data availability: No data was used for the research described in the article. Tue, 10 Mar 2026 00:00:00 GMT http://bura.brunel.ac.uk/handle/2438/33065 2026-03-10T00:00:00Z