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Most rapid prototyping (RP) relies on energy fields to handle materials, among which electricity has been much more utilized, resulting in distinctive responsiveness of non-linear, overshoot, variable inertia, etc. The purpose of this paper is to eliminate the drawbacks of array nozzle clogging, stringing, melt sagging, particularly in multi-material RP, by focusing on the electrothermal response so as to adaptively distribute thermal more accurate, rapid and balanced.

This paper presents an electrothermal response optimization method of nozzle structure for multi-material RP based on fuzzy adaptive control (FAC). The structural, physical and control model are successively logically built. The fractional order electrothermal model is identified by Riemann Liouville fractional differential equation, using the bisection method to approximate the physical model via least square method to minimize residual sum of squares. The FAC is thereafter implemented by defining fuzzy proportion integration differentiation control rules and fuzzy membership functions for fuzzy inference and defuzzification.

The transient thermodynamic and structural statics, as well as flow field analysis, are conducted. The response time, mean temperature difference and thermal deformation can be found using thermal-solid coupling finite element analysis. In physical experimental research, temperature change, together with material extrusion loading, were measured. Both numerical and physical studies have revealed findings that the electrothermal responsiveness varies with the three-dimensional structure, materials and energy sources, which can be optimized by FAC.

The proposed FAC provides an optimization method for extrusion-based multi-material RP between the balance of thermal response and energy efficiency through fulfilling potential of the hardware configuration. The originality may be widely adopted alongside increasing requirements on high quality and high efficiency RP.

The purpose of this paper was to synthesise a thermally expandable microsphere (TEMS) with fast thermal response property and small expansion temperature range, and investigate the factors affecting the expansion properties of the microspheres.

A new kind of TEMS with fast thermal response property was synthesised by suspension polymerisation method, using acrylonitrile, ethyl methacrylate and methacrylic acid as the main monomers; Mg(OH)₂ as the main dispersing agent; and isooctane or n-hexane or n-pentane as the blowing agent.

The TEMS possessed the best expansion capacity when encapsulated isooctane and n-hexane were about 18.5 Wt.%. The expansion process of the TEMS could be finished by raising the temperature to 18°C from the expansion onset, much less than the reported 30-50°C. The morphology of the TEMS turned from sphere to irregular concave shape following the content increase of the blowing agent.

A new kind of TEMS composed of acrylonitrile/ethyl methacrylate/methacrylic acid as the polymer shell was synthesised. These TEMS showed the fastest thermal response speed reported.

The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.

The temperature imaging or mapping techniques include thin coating methods such as liquid crystal thermography and fluorescence microthermography, contact mechanical methods such as scanning thermal microscopy, and optical techniques such as infrared microscopy and thermoreflectance. Their principles, characteristics and applications are discussed.

Thermal issues play an important part in optimizing the performance and reliability of high‐frequency and high‐packing density electronic circuits. To improve the performance and reliability of microelectronic devices and also to validate thermal models, accurate knowledge of local temperatures and thermal properties is required.

The paper provides readers, especially technical engineers in industry, a general knowledge of several commonly used thermography techniques in the semiconductor and micro‐device industries.

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities.

This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted.

This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures.

Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.

Fast, accurate digital readout of coating thickness is provided by the latest eddy current testing unit from Magnaflux Ltd.

Measurement of corrosion in water‐based environment. Cormon announce the completion of a development program, which, with the backing of major concerns in the measurement of erosion and corrosion will significantly improve the ability to accurately measure corrosion in acqueous environments.

The paper aims to capture the rack-level thermal dynamics in data center. It proposes the rack-level response experiments as well as transient Computational Fluid Dynamics (CFD) analysis to characterize the local thermal environment of the system.

A single sever simulator rack and its two neighboring racks with its cold and hot aisle containment have been modeled with known cold air supply temperature and flow rate for transient CFD analysis. The heat load was kept constant initially and varied case-to-case basis, which includes capturing the rack-level response with respect to changes in input. However, the response experiments on simulator rack were performed for 14 h by variation of server heat loads as step and ramp input.

The paper provides the detailed transient CFD analysis of data center racks. The local cold air flow rates and temperature at the vicinity of the racks showed significant effect due to changes in input. It was concluded that the rack-level dynamics impacts the thermal environment of data center and hence cannot be ignored.

The high computing devices and faster internet demands have led to major thermal management concerns for data center operators. To tackle this issue, capturing the system thermal dynamics is imperative. However, the system-level CFD analysis is computationally expensive. Therefore, this paper deals with the rack-level transient CFD study using commercial tool STAR CCM+.

This paper includes the modeling of the servers as a porous media as well as the multigrid method to enhance the computational speed. The successful implementation of this approach validated through experiments. This would help to establish a base for research in any type of data center.

This paper provides the porous media approach to model servers and multigrid method to enhance the computational speed. At the same time, the thought of characterizing the local dynamics at the vicinity of data center racks is unique.

The purpose of this study is to investigate the effect of the airgap on thermal behaviour and structural response of fabricated slim floor beams (FSFBs) in fire.

A detailed analytical model is established and validated by replicating the response of FSFBs. The validated finite element modelling method is then used to perform sensitivity analysis. First, the influence of the airgap presence is analysed, and later, the effect of the airgap size on thermal behaviour and structural response of FSFBs at elevated temperatures is investigated.

Results from the study demonstrate that the presence of the airgap has a considerable influence on their thermal behaviour and structural response of FSFBs. The size of the airgap, however, has no significant influence on their thermal and structural response in fire.

No investigations, experimental or analytical, are available in literature addressing the effect of airgap on the structural response of FSFBs in fire. The presence of airgap is helpful and beneficial; hence, the findings of this research can be used to develop designs for structural members with airgap as an efficient and inexpensive way to improve their response in fire.

The purpose of this paper is to develop, apply and validate a mesh-free graph theory–based approach for rapid thermal modeling of the directed energy deposition (DED) additive manufacturing (AM) process.

In this study, the authors develop a novel mesh-free graph theory–based approach to predict the thermal history of the DED process. Subsequently, the authors validated the graph theory predicted temperature trends using experimental temperature data for DED of titanium alloy parts (Ti-6Al-4V). Temperature trends were tracked by embedding thermocouples in the substrate. The DED process was simulated using the graph theory approach, and the thermal history predictions were validated based on the data from the thermocouples.

The temperature trends predicted by the graph theory approach have mean absolute percentage error of approximately 11% and root mean square error of 23°C when compared to the experimental data. Moreover, the graph theory simulation was obtained within 4 min using desktop computing resources, which is less than the build time of 25 min. By comparison, a finite element–based model required 136 min to converge to similar level of error.

This study uses data from fixed thermocouples when printing thin-wall DED parts. In the future, the authors will incorporate infrared thermal camera data from large parts.

The DED process is particularly valuable for near-net shape manufacturing, repair and remanufacturing applications. However, DED parts are often afflicted with flaws, such as cracking and distortion. In DED, flaw formation is largely governed by the intensity and spatial distribution of heat in the part during the process, often referred to as the thermal history. Accordingly, fast and accurate thermal models to predict the thermal history are necessary to understand and preclude flaw formation.

This paper presents a new mesh-free computational thermal modeling approach based on graph theory (network science) and applies it to DED. The approach eschews the tedious and computationally demanding meshing aspect of finite element modeling and allows rapid simulation of the thermal history in additive manufacturing. Although the graph theory has been applied to thermal modeling of laser powder bed fusion (LPBF), there are distinct phenomenological differences between DED and LPBF that necessitate substantial modifications to the graph theory approach.

Standard fire resistance curves such as ASTM E119 have been used for so long in structural fire practice. The issue with use of these curves that they do not represent real fire scenarios. As a result, the alternatives have been to either conduct experiments or find other tools to represent a real fire scenario. Therefore, the purpose of this paper is to understand the temperature effects resulted from a designed fire on steel beams and whether the standard fire curves represent a designed fire scenario.

Computational fluid dynamics (CFD) models were developed to simulate a designed fire scenario and to understand the structural responses on the beams under elevated temperatures. Consequently, the results obtained from the CFD models were compared with the results of three-dimensional (3D) non-linear finite element (FE) models developed by other researchers. The developed FE models were executed using a standard fire curve (ASTM E119). A parametric study including two case studies was conducted.

Results obtained from performing this study showed the importance of considering fire parameters such as fuel type and flame height during the thermal analysis compared to the standard fire curves, and this might lead to a non-conservative design as compared to the designed fire scenario. The studied cases showed that the steel beams experienced more degradation in their fire resistance at higher load levels under designed fires. Additionally, the models used the standard fire curves underestimated the temperatures at the early stages.

This paper shows results obtained by performing a comparison study of models used ASTM E119 curve and a designed fire scenario. The value of this study is to show the variability of using different fire scenarios; thus, more studies are required to see how temperature history curves can be used to represent real fire scenarios.