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The purpose of this paper is to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with two immiscible fluids of nanofluid and air.

One surface of the enclosure is jagged and another one is smooth. The finite volume approach is applied for computation. There are two partially side heaters. Furthermore, the Navier–Stokes equations and entropy generation formulation are solved in the 3D form.

The effects of different governing parameters, such as the jagged surface (JR=0, 0.02, 0.04, 0.08, 0.12 and 0.16), Rayleigh number (10³⩽Ra⩽10⁶) and solid volume fraction of nanofluid (φ=1, 1.5, 2 vol%), on the fluid flow, temperature field, Nusselt number, volumetric entropy generation and Bejan number are presented, comprehensively. The results indicate that the average Nusselt number increases with the increase in the Rayleigh number and solid volume fraction of nanofluid. Moreover, the flow structure is significantly affected by the jagged surface.

The originality of this work is to analyze the natural-convection fluid flow and heat transfer under the influence of jagged surfaces of electrodes in high-current lead–acid batteries.

The purpose of this paper is to investigate the effect of welding procedure on the corrosion behaviors of weathering steel 09CuPCrNi in marine atmospheric environment. The corrosion processes of weathering steel 09CuPCrNi and its welded joints in marine atmospheric environment were simulated by a salt spray dry-wet test.

The corrosion behaviors of the base metal and the welded joints at corrosion times of 2, 4, 8, 12, 24 weeks were investigated by weight loss test, electrochemical techniques, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The corrosion rates, as well as the morphologies and electrochemical characteristics of corrosion products, the distribution of major alloying elements in rust layer were obtained. The influence of welding on the atmospheric corrosion of 09CuPCrNi was studied.

The results indicate that the corrosion rate of the 09CuPCrNi welded joints decreases gradually with the corrosion time, and the major alloying elements are enriched in the inner rust layer, which are similar to that of the base metal. In the early stage during the corrosion process, the welded joints with inhomogeneous structure show the poorer corrosion resistance than that of the base metal. However, it looks the opposite way around in the late corrosion stage, when the uniform corrosion products with even thickness of the base metal tend to detach from the substrate easier and earlier and resulting in cracks, which increase the corrosion rate comparatively with that of the welded joints.

09CuPCrNi low alloy steel is a kind of typical weathering steel developed in China which is similar to Corten A developed by USA. Nowadays, 09CuPCrNi low alloy steel is widely adopted in many fields which require welding processes. In the past years, the research of weathering steel welded joints was mainly concentrated on the strength, toughness and weldability. Less work has been done to investigate the difference of corrosion evolution and characteristics between the base metal and its welded joints. Thus, the main objective of the present work was to analyze the influence of welding on the atmospheric corrosion.

Pores and shrink holes are unavoidable defects in the die-casting mass production process which may significantly influence the strength, fatigue and fracture behaviour as well as the life span of structures, especially if they are subjected to high static and dynamic loads. Such defects should be considered during the design process or after production, where the defects could be detected with the help of computed tomography (CT) measurements. However, this is usually not done in today's mass production environments. This paper deals with the stress analysis of die-cast structural parts with pores found from CT measurements or that are artificially placed within a structure.

In this paper the authors illustrate two general methodologies to take into account the porosity of die-cast components in the stress analysis. The detailed geometry of a die-cast part including all discontinuities such as pores and shrink holes can be included via STL data provided by CT measurements. The first approach is a combination of the finite element method (FEM) and the finite cell method (FCM), which extends the FEM if the real geometry cuts finite elements. The FCM is only applied in regions with pores. This procedure has the advantage that all simulations with different pore distributions, real or artificial, can be calculated without changing the base finite element mesh. The second approach includes the pore information as STL data into the original CAD model and creates a new adapted finite element mesh for the simulation. Both methods are compared and evaluated for an industrial problem.

The STL data of defects which the authors received from CT measurements could not be directly applied without repairing them. Therefore, for FEM applications an appropriate repair procedure is proposed. The first approach, which combines the FEM with the FCM, the authors have realized within the commercial software tool Abaqus. This combination performs well, which is demonstrated for test examples, and is also applied for a complex industrial project. The developed in-house code still has some limitations which restrict broader application in industry. The second pure FEM-based approach works well without limitations but requires increasing computational effort if many different pore distributions are to be investigated.

A new simulation approach which combines the FEM with the FCM has been developed and implemented into the commercial Abaqus FEM software. This approach the authors have applied to simulate a real engineering die-cast structure with pores. This approach could become a preferred way to consider pores in practical applications, where the porosity can be derived either from CT measurements or are artificially adopted for design purposes. The authors have also shown how pores can be considered in the standard FEM analysis as well.

Cathodic protection used in conjunction with surface coatings is now an accepted part of the engineering world, yet relatively little has been done to produce new types of coatings suitable for this important application. The author, who gives here a summary of the information at present available, hopes that some fundamental research can soon be started.

TWO nickel‐bearing commercial steels were oxidised in the range 1100°–1250°C for up to 8 hr. in air and CO2. The increase in thickness of the scale and the inner layer with embedded metal particles was followed in detail. A distinction is made between filaments which retain continuity with the base metal and discrete particles. The continuous filaments may be of practical importance in holding the scale to the metal in hot rolling, leading to surface defects on hot‐rolled products.

Additive manufacturing (AM) technologies, also known as three-dimensional printing (3DP), is a technological breakthrough that have the potential to disrupt the traditional operations of supply chains. They open the way to a supply chains innovation that can significantly benefit hospitals and health-related organizations in dealing with crises or unexpected events in a faster and more flexible way. In this study the authors identify the boundary of this potential support.

The authors adopt a case study approach to understand the dynamics behind a well-known best practice to identify the main opportunities and the main pitfalls that AM may pose to health-related organizations wanting to leverage them.

The case highlights that it is possible to increase hospital flexibility using AM and that by leveraging the Internet it is possible to spread the benefits faster than what it would be normally possible using traditional supply chain processes. At the same time the case highlights that leveraging these technologies needs buy-in from all the relevant stakeholders.

The paper is one of the first, to the best of the authors' knowledge, to highlight the main opportunities and difficulties of implementing 3DP technologies in hospital supply chain management.

A numerical procedure is described for the elastic—plastic finite element analysis of crack propagation with branching. Constraint equations are used to model crack closing and sliding. Constraint conditions are imposed by using a penalty method for the self‐similar crack propagation and an elimination method for the off‐axis propagation. The contact condition is examined during plasticity iterations. The use of multiple constraints at the crack branching point to determine the mode of contact is discussed in detail. The method is then applied to (i) the self‐similar crack growth in a single‐edge notch specimen, (ii) the self‐similar propagation followed by interfacial splitting in a center‐cracked 0° composite plate, and (iii) the bifurcation of a crack in a compact tension specimen.

The construction industry relies increasingly on profits generated from high utilisation of mechanisation. Interruption of this mechanical supply not only incurs the “tangible” costs of labour, replacement parts and consumables, but also the less tangible costs of delays to contract, possible loss of client goodwill and ultimately, loss of profit. Cumulative costs associated with plant breakdown are therefore significant. Predictive maintenance (PM) techniques have evolved to keep a check on mechanical health, by generating information on machine condition. Such data allow just in time maintenance to be conducted. However, recent developments have witnessed an increased interest in determining “root cause” of failure as opposed to monitoring the time to breakdown once the wear process has begun. This paper reviews condition based monitoring (CBM) technologies and introduces the evolving concept of root cause analysis. Both these could have particular relevance to construction plant and equipment. In summary, the paper presents initial findings of ongoing research, which is the development of a model for predicting construction plant and equipment breakdown.

This paper aims to present the methodology and results of the experimental characterization of three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) parts utilizing digital image correlation (DIC).

Tensile and shear characterizations of ABS and PC 3D-printed parts were performed to determine the extent of anisotropy present in 3D-printed materials. Specimens were printed with varying raster ([+45/−45], [+30/−60], [+15/−75] and [0/90]) and build orientations (flat, on-edge and up-right) to determine the directional properties of the materials. Tensile and Iosipescu shear specimens were printed and loaded in a universal testing machine utilizing two-dimensional (2D) DIC to measure strain. The Poisson’s ratio, Young’s modulus, offset yield strength, tensile strength at yield, elongation at break, tensile stress at break and strain energy density were gathered for each tensile orientation combination. Shear modulus, offset yield strength and shear strength at yield values were collected for each shear combination.

Results indicated that raster and build orientations had negligible effects on the Young’s modulus or Poisson’s ratio in ABS tensile specimens. Shear modulus and shear offset yield strength varied by up to 33 per cent in ABS specimens, signifying that tensile properties are not indicative of shear properties. Raster orientation in the flat build samples reveals anisotropic behavior in PC specimens as the moduli and strengths varied by up to 20 per cent. Similar variations were observed in shear for PC. Changing the build orientation of PC specimens appeared to reveal a similar magnitude of variation in material properties.

This article tests tensile and shear specimens utilizing DIC, which has not been employed previously with 3D-printed specimens. The extensive shear testing conducted in this paper has not been previously attempted, and the results indicate the need for shear testing to understand the 3D-printed material behavior fully.