Water towers represent a specific class of elevated structures whose structural integrity is governed by the interaction between geometric configuration, material properties, loading conditions, and long-term degradation processes. Many existing water towers were designed several decades ago and are currently operating beyond their original design life which raises concerns regarding their safety and serviceability under contemporary loading requirements. This paper provides a structured overview of water towers from the perspective of structural integrity and remaining life considerations. Particular emphasis is placed on wind and seismic loading effects, material behaviour, and assessment challenges relevant to existing structures. Typical structural configurations and materials are reviewed, and key issues related to inspection, analysis, and integrity evaluation are discussed. The paper aims to support engineers and researchers involved in the assessment and maintenance of water towers by highlighting critical aspects influencing their struc¬tural performance and long-term reliability.
The current study involves the production of composites consisting of Al2005 alloy and B4C using a liquid metallurgical technique. The Al2005 alloy is employed to fabricate composites with 4 and 8 weight percent of B4C particles. The microstructure of the produced composites is examined utilising Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The density, hardness, ultimate strength, yield strength, and elongation are assessed according to the ASTM E8 standard for tensile testing and the E10 standard for hardness testing. The consistent distribution of B4C particles throughout the Al2005 alloy is validated by SEM. EDS analyses indicate the existence of B4C particles within the Al2005 alloy. The incorporation of lighter B4C particles into the matrix diminishes the density of aluminium alloy composites. The incorporation of particles results in an improvement in the hardness, ultimate tensile strength, and yield strength of the Al2005 alloy by 33.73 %, 36 %, and 41.84 %, respectively. The tensile fractured micrographs offer additional proof of the distinct fracture characteristics shown by the Al2005 alloy and its composites.
This study examines the thermal behaviour of edge-loaded disks composed of polystyrene and natural rubber under varying temperatures (T = 0 and T = 0.5). The relationship between angular speed and radius ratio is analysed, revealing that natural rubber disks require higher angular speeds for initial yielding and plastic deformation compared to polystyrene. As the radius ratio increases, angular speed decreases, especially in fully plastic conditions. Elevated temperatures enhance angular speeds for both materials, indicating improved performance. These findings highlight the critical impact of material composition and thermal conditions on the mechanical response of rotating disks, offering valuable insights for engineering applications involving composites.
The current study involves the production of composites consisting ofAl2005 alloy and B4C using a liquid metallurgical technique. The Al2005 alloy is employed to fabricate composites with 4 and 8 weight percent of B4C particles. The microstructure of the produced composites is examined utilising Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The density, hardness, ultimate strength, yield strength, and elongation are assessed according to the ASTM E8 standard for tensile testing and the E10 standard for hardness testing. The consistent distribution of B4C particles throughout the Al2005 alloy is validated by SEM. EDS analyses indicate the existence of B4C particles within the Al2005 alloy. The incorporation of lighter B4C particles into the matrix diminishes the density of aluminium alloy composites. The incorporation of particles results in an improvement in the hardness, ultimate tensile strength, and yield strength of the Al2005 alloy by 33.73 %, 36 %, and 41.84 %, respectively. The tensile fractured micrographs offer additional proof of the distinct fracture characteristics shown by the Al2005 alloy and its composites.
Recent advancements in polymer welding have spotlighted Friction Stir Welding (FSW) as a promising method for creating durable joints in high-density polyethylene (HDPE) without melting the material. This research delves into how three critical factors: tool pin shape, rotation speed, and travel speed affect the ultimate tensile strength (UTS) and ultimate elongation (UE) of the welded HDPE. Two distinct tool pin geometries, cylindrical and hexagonal, are employed to evaluate their effect on the quality of the welded HDPE. A full 23 factorial experimental design is used to study the effect of each parameter, while regression equations are employed to forecast the resulting mechanical properties. The study reveals that the tool pin geometry is the most influential parameter on both ultimate tensile strength and ultimate elongation, with the hexagonal pin yielding stronger welds due to improved stirring action. The welding gave generally good results concerning the UTS in the contrary of UE, where it gave unsatisfactory results. Statistical analyses, like ANOVA confirm the dominant influence of tool pin geometry and give a detailed information about the contribution of all parameters and their interaction on the final weld quality. These findings provide insights into optimising FSW parameters for polymer welding applications.
In order to optimise surface characteristics, corrosion and scratch damage, as important factors for accepting a metallic implant at conditions of a human body, commercially pure titanium (cpTi) can be modified by different treatments, including high pressure torsion (HPT) and anodic oxidation (AO). Here, a nanotube oxide layer on the surface of ultrafine-grained commercially pure titanium (UFG cpTi) is formed using AO in 1M H3PO4 + NaF solution during 60 min. SEM microphotographs show that AO with selected parameters can lead to the formation of a highly regular oxide layer with nanotubes on the surface of UFG cpTi. Determination of the surface contact angle shows that the surface of UFG cpTi after AO is more hydrophilic than before AO treatment. In order to characterise the surface topography and adhesion of formed nanotubes, scratch testing on the UFG cpTi surface after AO treatment is done. Corrosion resistance is tested in Ringer's solution with pH value of 5.5 at 37 degrees C to simulate the environment in the human body. UFG cpTi before and after AO is analysed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation. The inner barrier and outer porous surface layers are highly resistant with capacitive behaviour for both tested materials, but the synergistic action of HPT and AO treatments led to improved corrosion resistance and therefore a reduced corrosion rate for commercially pure titanium in the conditions of the human body.
The mechanical performance of a product manufactured by injection moulding depends largely on the presence of weld lines, whose occurrence is often inevitable during a production cycle. Due to poor material bonding, the weld line shows loss of strength and impact resistance under the influence of external loads, threatening the overall integrity of the product. These negative effects are particularly pronounced in short fibre reinforced composites, because there is also a local non-uniform fibre orientation. One way to mitigate these effects is to use an overflow tab, in order to create the underflow through the core material layer after the weld line is initially formed. In recent years, due to the extremely complex behaviour of short fibre reinforced composites during injection moulding, the application of numerical simulation to describe these phenomena has gained great importance. The paper presents the application of Moldex3D Studio software to predict the influence of the overflow tab on the localised reduction of mechanical properties at weld lines. This involves describing changes in the distribution of fibre orientation tensor components as well as changes in the position and shape of the weld line region.
Bearing in mind the use of fine-grained micro alloyed steel NIOMOL 490K for welded structures exposed to impact loading at low temperatures, the mechanical and metallographic properties of its welded joint obtained by submerged arc welding (SAW), are examined. A filler metal, EPP 2NiMo2 & Oslash;4 mm wire is used, in combination with OP 40 TT flux powder. The final aim of this research is to analyse the behaviour of welded joints under impact load at low temperatures in order to evaluate its fitness-to-service in real operating conditions.
This study examines the performance of cast iron and stainless steel brake discs under varying loads and temperatures, with a focus on angular speed, radial stress, and circumferential stress. The results show that angular speed decreases with higher radii ratios and loads for both materials, with cast iron outperforming stainless steel due to its lower density and higher stiffness. Stainless steel exhibits higher radial stress and greater sensitivity to temperature changes. Circumferential stress decreases with the radii ratio, with stainless steel consistently showing higher stress efficient in maintaining angular speed, while stainless steel is more sensitive to stress and temperature variations.
In this paper we examine the heat transfer characteristics of three-dimensional rotating flow of convective hybrid nanofluid flow over a stretching/shrinking permeable sheet in the presence of a magnetic field and heat source effects. Hybrid nanofluids exhibit promising characteristics for various applications, particularly in enhancing heat transfer rates. The hybrid nanofluid used in the paper is alumina (Al2O3) and copper (Cu) with water (H2O) serving as the base fluid. The governing nonlinear partial differential equations are transformed into linear ordinary differential equations using similarity transformations and are numerically solved using the bvp4c function in MATLAB (R) software. The influence of various governing parameters on the velocities and temperature profiles is represented through graphs. The parameters include magnetic field, Darcy permeability, Eckert number, suction effects, Biot number, rotating parameter, and heat source parameter. Further, the impact of suction parameter on the skin friction and reduced heat transfer is also examined.
Recently, during rehabilitation of RHPP in 2025, cracks were discovered in rotor spoke ribs. It was determined that cracking was caused by unexpected overloading due to weight. It was also concluded that cracks cannot be grooved and surface welded due to very limited space and some other limitations. Thus, a different approach had to be taken, leading to a reconstruction of the rotor spoke. To do so, it was necessary to stress release the rotor spoke ribs which was done by hydraulic lifting the whole rotor and then by strengthening the spoke ribs by new additional rib elements. This solution is based on detailed 2D and 3D stress analysis performed by the finite element method.
This study investigates the stability of thermosolutal convection in Walter's (model B)' nanofluid saturated in a porous medium under two different boundary conditions: rigid-rigid and rigid-free. Linear stability analysis is conducted using perturbation theory and normal mode analysis to evaluate the system's stability. The effects of Brownian motion and thermophoresis are incorporated into the nanofluid model. The nanoparticle Rayleigh number, thermosolutal Lewis number and solutal Rayleigh number have a destabilising effect, enhancing the onset of convection. In contrast, parameters such as porosity, thermo-nanofluid Lewis number, modified diffusivity ratio, Dufour parameter and Soret parameter have a stabilising effect, delaying the onset of convection. Effects of these parameters are presented graphically using MATLAB (R) software. This study improves the understanding of thermosolutal convection in nanofluid-saturated in a porous medium, with implications for optimising heat and mass transfer in applications like chemical reactors, oceanic convection, material synthesis, food processing and biological systems.
Properties of fine-grained soils, such as the liquid and plastic limits, are widely used as indicators of geotechnical behaviour. Unlike the liquid limit that can be reliably determined by mechanical testing, the determination of the plastic limit is significantly more complex, and the standard thread-rolling test is increasingly criticised for its subjective nature. Therefore, there is a need for a standardised, mechanical, more reliable and reproducible method to determine the plastic limit. This study compares several alternative methods with the standard rolling test, including tests using 240 g and 400 g cones, the cone penetration index (beta), and an empirical method based on undrained shear strength data. The accuracy of each method is evaluated using MAE, RMSE, and MAPE. The results show that the beta method provides the highest reliability, while the empirical approach shows moderate accuracy.
Self-compacting geopolymer concrete (SCGPC) is an ecofriendly substitute to traditional Portland cement concrete, known for its lower carbon footprint. This study compares two different types of SCGPC made from fly ash, ground granulated blast furnace slag (GGBFS), and waste ceramic powder (WCP), which are subjected to ambient and oven curing at 60 degrees C and 80 degrees C for durations of 24 and 48 hours. The focus has been on the use of WCP in SCGPC, which is essentially industrial waste that can be used in the construction industry. Two batches of SCGPC are prepared: one with 60 % fly ash, 30 % GGBFS, and 10 % WCP (F60G30W10) and another with 70 % fly ash, 30 % GGBFS, and 0 % WCP (F70G30W0). The study investigates the effect of different curing conditions on the fresh state properties, mechanical properties, as well as microstructural characteristics. The results reveal that curing plays a very significant role in enhancing the strength of the SCGPC. In the oven-cured at 80 degrees C, the compressive strength (CS) of the SCGPC mix F60G30W10 is 33.7MPa at 28 days, which was 3.37 % higher than that of the oven-cured mix F60G30W0 under similar curing conditions. Scanning electron microscopy (SEM) analyses confirm that the SCGPC microstructure improves with oven curing. X-ray diffraction (XRD) analysis shows that increased curing temperature and WCP content led to higher intensities of mullite, quartzite, CSH gel, and calcite peaks compared to those observed in composite F70G30W0.
The application of continuously inhomogeneous structural materials in various spheres of modern engineering constantly increases. Very often these materials are used for manufacturing different members and components of machines and mechanisms which perform non-uniform motion. Inertia loads generated by acceleration have to be taken into account when studying fracture in non-uniformly moving members. The current paper concentrates on the effect of energy dissipation on lengthwise fracture in a continuously inhomogeneous beam member that moves up at a varying acceleration. The beam has nonlinear viscoelastic behaviour. A theoretical model with a linear spring and a nonlinear dashpot subjected to time-dependent stress is applied for describing the viscoelastic behaviour of the beam. There are two symmetric lengthwise cracks in the moving beam. The lengthwise fracture under the action of the inertia loads is analysed by the J integral. The effect of energy dissipation is taken into account in the analysis by using the reduced specific strain energy. The latter is extracted from the stress in the spring only (the dashpot dissipates the energy). The J integral solution is checked-up by deriving the strain energy release rate in the beam under inertia loads with considering the effect of energy dissipation. A detailed analysis of the influence of the acceleration of the beam, energy dissipation, mass distribution, and parameters of the viscoelastic model on lengthwise fracture is performed. Applications of the analysis in structural design of moving beams with taking into account the energy dissipation are presented.
Water towers represent a specific class of elevated structures whose structural integrity is governed by the interaction between geometric configuration, material properties, loading conditions, and long-term degradation processes. Many existing water towers were designed several decades ago and are currently operating beyond their original design life which raises concerns regarding their safety and serviceability under contemporary loading requirements. This paper provides a structured overview of water towers from the perspective of structural integrity and remaining life considerations. Particular emphasis is placed on wind and seismic loading effects, material behaviour, and assessment challenges relevant to existing structures. Typical structural ers involved in the assessment and maintenance of water tural performance and long-term reliability.
To predict the dynamic behaviour of structures under the effect of impact, we approach the dynamic problem in the form of a numerical simulation of impact on a cracked plate. Our choice is focused on a numerical simulation in order to examine the response of a cracked aluminium alloy plate impacted by a spherical steel projectile. The use of ANSYS (R) LS Dyn (dynamic explicit) software allows us to study this behaviour as a function of the boundary conditions, and the geometric parameters of a plate and the sphere, taking into account the variation of the crack length. A comparison is made with the case of a healthy plate without defects dynamically stressed under the same conditions. In addition, the alent elastic deformations are carried out.
The increasing need for energy and the need to ensure sustainable development and ecology of the environment places forward new requirements for improving the technology and increasing the production of liquefied natural gas (LNG). It is possible to solve such problems only by simultaneous involvement of mathematical, physical and technical, and technological methods. At the same time, the development of such optimisation solutions can be carried out for specific equipment, which will allow to increase the productivity and quality of LNG production technology as a whole. One of the key elements of LNG production process chain is cryocondensation. The equipment used in this process is subjected to a wide range of physical and chemical influences, and its design and operating principle have significant impact on LNG production. An important element of system operation which requires improvement is the rapidity of operation of the cryocondensation pump. The operation speed is conditioned by a large complex of interrelated and complicated processes: mass and heat transfer, phase transformations, continuous growth of the cryo-sediment, formation and constant change of the structure and thermophysical properties of the cryo-sediment. Besides, it is necessary to pump out not a single-component gas, but a multicomponent gas medium having different thermophysical properties. Understanding the nature of forces holding gas particles on the cooled surface, as well as the mechanism of cryocondensation capture of gas molecules is one of the most difficult problems of modern physics and the subject of numerous experimental and theoretical works. Fast performance of the cryocondensation pump determines the amount of useful product output and affects its quality. In this study we set a task to carry out mathematical modelling of the cryocondensation pump performance and analyse the factors affecting the process. Taking into account the obtained model, technical solutions that improve the quality of cryocondensation pump operation are formed.
This research explores the impact of rotation and vertical alternating current (AC) electric fields on the onset of convective instability within a rheological dielectric nanofluid layer heated from below and saturated by a Darcy porous medium. Linear stability analysis is employed, and the system’s coupled differential equations are analytically solved under stress-free boundary conditions using the normal mode method. The study examines the influences of parameters such as the modified diffusivity ratio, AC electric Rayleigh number, nanofluid Lewis number, solutal and nanoparticle Rayleigh numbers, porosity, and Taylor number on stationary convection. Results indicate that an increasing nanofluid Lewis number, solutal and nanoparticle Rayleigh numbers, AC electric field, and modified diffusivity ratio accelerate the onset of stationary convection, while the increase of Taylor number and porosity delay it.
This research introduces a novel framework for structural health monitoring technique selection by integrating spherical fuzzy sets with multi-criteria decision-making methods. The approach enhances traditional Multi-Criteria Decision-Making methods by addressing uncertainty and vagueness in expert judgments. A case study validates its effectiveness, showing more reliable outcomes compared to conventional methods. The framework offers a robust tool for optimising structural health monitoring techniques, improving infrastructure safety and sustainability.
