Search

This study investigates the effects of process parameters including scanning strategy, build orientation, and hatching distance on the mechanical properties of AlSi10Mg parts produced by Laser Powder Bed Fusion (L-PBF). The experiment varied these parameters within defined ranges and used statistical analysis to evaluate their impact on tensile strength and ductility. Results showed that scanning strategy had the greatest influence, followed by hatching distance, while build orientation affected anisotropic properties. Microstructural analysis showed clear correlation between process conditions and mechanical strength, thereby showing the underlying mechanisms that govern material behavior. Moreover, Machine learning models, including Random Forest Regression (RFR), Support Vector Regression (SVR), and Artificial Neural Networks (ANNs), were applied to predict tensile strength and ductility characteristics. RFR and SVR outperformed ANNs, showing high predictive accuracy with limited datasets. These findings emphasize the importance of optimizing L-PBF process parameters to minimize anisotropy and achieve consistent mechanical properties in produced parts. [ABSTRACT FROM AUTHOR]

Background: Supply chain performance (SCP) is impacted by complexity brought about by static and dynamic drivers. This study aims to investigate the effects of supply chain complexity (SCC) on SCP and ascertain whether additive manufacturing best practices have moderating effects on this relationship. Methods: Using data from 29 Ethiopian footwear industries and 205 respondents, the relationship established in the theoretical framework was validated using structural equation modelling (SEM). Results: The study's findings provided several important insights. First, upstream supply chain complexity (USSCC), midstream supply chain complexity (MSSCC), and downstream supply chain complexity (DSSCC) negatively affect SCP. Second, additive manufacturing best practices have significant moderation effects between supply chain complexity and supply chain performance. Third, the negative impacts of USSCC and MSSCC on SCP are reduced at a higher level of additive manufacturing adaptation. The findings of this study also revealed that the effects of DSSCC on SCP have no difference at both low and high levels of additive manufacturing best practices. Conclusions: This work offers the first empirical investigation to which the detrimental effects of SCC on SCP are mitigated or improved through the moderating role of additive manufacturing best practice. [ABSTRACT FROM AUTHOR]

Metal matrix composites (MMCs) epitomize a promising class of resources in modern manufacturing, offering an enhanced strength-to-weight ratio and high-temperature performance which make them ideal for applications demanding over conventional metals. However, their machining presents significant challenges due to their inherent material properties. The conventional machining methods including turning, milling, drilling, shaping, and the grinding of MMCs pose several challenges, facing limitations in terms of sustainability and efficiency. This paper explores the current perspective and prospects of the conventional machining techniques applied to MMCs, emphasizing sustainable manufacturing practices. Key aspects include the challenges posed by MMCs' inherent heterogeneity, the MMC materials used, the MMC manufacturing process, the cutting constraints employed, tool wear, surface unevenness, surface integrity, and high energy consumption throughout machining. The study also explores promising advancements in tooling materials, cutting parameters' optimization, innovative machining techniques aimed at minimizing the environmental impact and maximizing material utilization, and the strategies developed to overcome these challenges. The paper concludes by highlighting optimizing tools, and processes, and adopting emerging optimization techniques and opportunities for further research aimed at the industry, allowing it to move towards more efficient, eco-friendly production methods. [ABSTRACT FROM AUTHOR]

Natural fibers are among the most employed reinforcements in the manufacturing process of innovative fiber-based composite materials. As with any composite materials, the properties of composites depend on the type and properties of the fiber, fiber structure, composition (hybridization), and treatment. In this study, the composite was fabricated by using hand lay-up with 100/0, 75/25, 50/50, 25/75, and 0/100 Enset/Sisal (E/S) hybridization ratio. Three cases, i.e., untreated, 5%, and 10% NaOH treatment were considered. The effects of hybridization and treatment on the mechanical and water absorption properties of woven and unidirectional orientation of E/S hybrid composite were evaluated by using a two-factors analysis of variance. The fiber–matrix interfacial fractured surface was characterized by scanning electron microscopy. The treated (5% NaOH) and woven fiber orientation exhibited better mechanical properties than untreated and unidirectional hybrid composites. The flexural and tensile strength of the woven composite was improved by 5% and 9%, respectively, when compared with woven untreated 50/50 volume ratio of composites. In both samples and orientations, the hybridization effects show a higher percentage contribution to the mechanical properties. But, in both orientations of composite samples, the treatment effects show a higher percentage contribution for water absorption properties. [ABSTRACT FROM AUTHOR]

Background: The objective of this literature review is to systematically explore the supply chain (SC)-related issues of additive manufacturing (AM)-based production processes. For SC sustainability, efficiency, and performance improvements, the adoptation of disruptive technologies like AM plays a vital role, because the product's SC benefits in terms of reduced total lead time and costs. Methods: To explore the state-of-the-art influences of AM on the SC in this study, 978 papers published in peer-reviewed journals from 2004 to 2023 were retrieved, and 70 of these were identified as the most relevant and then reviewed. Results: As an outcome, the results of this review paper indicated a lack of documented studies in developing countries and, as a result, limited research works, for instance, in fashion industries were observed. In addition, AM best practices in the SC context have been identified and categorized as cost-related, time-related, inventor-related, as well as energy-, waste-, and environment-related factors, SC efficiency factors, and flexibility, marketing, and manufacturing-related factors. Conclusions: By identifying these categories, the study aims to contribute to the efforts of transforming traditional manufacturing into AM-based processes, for which a framework for the AM SC implementation is developed. In summary, the systematic review indicated that further research work is needed on the impacts of the identified AM best practices on SC performance. [ABSTRACT FROM AUTHOR]

Aluminium is a noncorrosive, lightweight material used to fabricate parts for the aerospace, automobile, and construction industries. Due to the low-temperature resistance, more heat is generated. At the same time, in machining, tremendous efforts are taken to keep friction and chatter to a minimum and to attain better quality and perfect output, and also more attention is required while selecting the machining process parameters. Spindle speed, rate of feed, radial and axial depth of cut, and radial rake angle of the tool are the parameters utilized to machine aluminium 6063 using the HSS tool on CNC milling to estimate spindle and worktable vibration using a prediction model. In this study, the design of the experiment of the response surface methodology approach is used to create a second-order statistical equation for experimentation with the Design-Expert v12 software. The performance characteristics are analyzed using the ANOVA method. The spindle speed achieved the lowest vibration between 2000 and 3000 rpm. Next, axial and radial depths were the most vibration-affecting parameter compared to the rate of feed and radial rake angle of the tool. To find the best feasible response, the nondominant sorting genetic algorithm II (NSGA II) approach was trained and tested using MATLAB software. Using a Pareto-optimal technique, the optimum worktable vibration ranged from 0.00284 to 0.00165 mm/s2, whereas the spindle vibration ranged from 0.02404 to 0.01336 mm/s2. The predicted values were found to be in an excellent argument when Pareto-optimal solutions are used. [ABSTRACT FROM AUTHOR]

Thin-walled structures are a significant and growing portion of engineering construction, with a wide range of applications, including storage vessels, industrial buildings, warehouses, aircraft, automobiles, bridges, ships, and oil rigs. Thin-walled components with minimum thickness without compromising strength and other quality characteristics are the desire of modern industry. Reducing wall thickness not only aids in lowering the cost of production. It also improves the effectiveness of engineering systems, resulting in lower fuel consumption and lower emissions of hazardous gases to the environment. Nowadays, even though thin-walled parts are demanded, the constraints of the production process, quality, and reliability are the concerns of current research and development. The ability to produce parts with intricate geometries and tight dimensional tolerances are important criteria for advanced manufacturing processes. In the early days of society, investment casting was used to produce jewelry, weapons, and statues. In modern industry, investment casting is still used to produce thin-walled and intricate parts such as turbine blades. The current advancements in SLM, which has the capacity to produce thin-walled and intricate parts, have recently attracted attention due to several benefits, such as the supreme degree of design freedom and the viability of tool-free production directly from CAD data. However, the current technological applications of SLM and investment casting are crucial for producing parts at the desired quality and reliability. This review article focuses on comparative studies of SLM and investment casting at the current technology level. The basis of comparison via systematic approach is mechanical characterization; quality in terms of porosity, microstructure, surface roughness and dimensional accuracy; and residual stress. Therefore, the latest open scientific sources published are considered to obtain sufficient literature coverage. Better tensile strength and fine microstructure are found in SLM, while better surface quality, fatigue load resistance, ductility, and residual stress are found in investment casting. The research gap for further investigation is indicated. [ABSTRACT FROM AUTHOR]

Currently, hybridizing natural fibers with synthetic fiber is considered as the best solution for reducing the environmental pollution and the cost of materials. This is due to the lower mechanical properties and high water absorption capacity problems of natural fiber reinforced composites and nonbiodegradability and high-cost problem of synthetic fibers that can be solved by hybridizing them. This article aims to investigate the influence of the weight fraction of the sisal fiber on the mechanical property of the E-glass-sisal fiber reinforced epoxy matrix composite. The sisal fiber was treated by 8% sodium hydroxide (NaOH) for three hours. The samples of five different weight fractions of fibers (0%, 20%, 30%, 40%, and 60%) with a constant weight fraction of epoxy matrix (40%) were prepared as per the ASTM standard prepared by the manual hand layup method at room temperature. The tensile, compression, and flexural tests of the samples were carried out on the WP 310 universal testing machine. From the experimental results, it has been observed that the increasing weight fraction of the sisal fiber greatly influences the mechanical properties (tensile, compression, and flexural) of E-glass-sisal hybrid reinforced epoxy matrix composites. From all the tested samples, those consisting of 60% E-glass and 0% sisal fibers with 40% epoxy matrix showed better mechanical properties than other hybrid samples with tensile, compressive, and flexural strengths of 464.03 MPa, 40.1 MPa, and 239.06 MPa, respectively. [ABSTRACT FROM AUTHOR]

Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame's equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm. [ABSTRACT FROM AUTHOR]

Additive manufacturing has gained significant popularity from a manufacturing perspective due to its potential for improving production efficiency. However, ensuring consistent product quality within predetermined equipment, cost, and time constraints remains a persistent challenge. Surface roughness, a crucial quality parameter, presents difficulties in meeting the required standards, posing significant challenges in industries such as automotive, aerospace, medical devices, energy, optics, and electronics manufacturing, where surface quality directly impacts performance and functionality. As a result, researchers have given great attention to improving the quality of manufactured parts, particularly by predicting surface roughness using different parameters related to the manufactured parts. Artificial intelligence (AI) is one of the methods used by researchers to predict the surface quality of additively fabricated parts. Numerous research studies have developed models utilizing AI methods, including recent deep learning and machine learning approaches, which are effective in cost reduction and saving time, and are emerging as a promising technique. This paper presents the recent advancements in machine learning and AI deep learning techniques employed by researchers. Additionally, the paper discusses the limitations, challenges, and future directions for applying AI in surface roughness prediction for additively manufactured components. Through this review paper, it becomes evident that integrating AI methodologies holds great potential to improve the productivity and competitiveness of the additive manufacturing process. This integration minimizes the need for re-processing machined components and ensures compliance with technical specifications. By leveraging AI, the industry can enhance efficiency and overcome the challenges associated with achieving consistent product quality in additive manufacturing. [ABSTRACT FROM AUTHOR]

A walking machine (robot) is a type of locomotion that operates by means of legs and/or wheels on rough terrain or flat surface. The performance of legged machines is greater than wheeled or tracked walking machines on an unstructured terrain. These types of machines are used for data collections in a variety of areas such as large agricultural sector, dangerous and rescue areas for a human. The leg mechanism of a walking machine has a different joint in which a number of motors are used to actuate all degrees of freedom of the legs. In the synthesis of walking machine reported in this article, the leg mechanism is developed using integration of linkages to reduce the complexity of the design and it enables the robot to walk on a rough terrain. The dimensional synthesis is carried out analytically to develop a parametric equation and the geometry of the developed leg mechanism is modelled. The mechanism used is found effective for rough terrain areas because it is capable to walk on terrain of different amplitudes due to surface roughness and aerodynamics.

In this paper, the results of experimental and numerical studies on joining the thin fins to the thick base plate of a heat exchanger are presented. The elements of the heat exchanger were joined by using developed method of press forming. The joining technology consists in clamping the sheet metal into the channel of the base plate using a punch with specific geometry. The effect of different configurations of the punch geometry (shape, radius and distance between fin and punch) and the indentation depth on the depth of the interface between the fin and base plate is analysed. Furthermore, the effect of different combinations of fin-base plate materials has been numerically studied. The plate material was the AA2219 -T851 aluminium alloy, while the fins were made of the AA5251 aluminium alloy. The elastic-plastic numerical computations of the joining process have been carried out using the finite element-based MSC.Marc program. It was found that the area of the contact of the fin with the base plate can be optimised by choosing the right parameters of the tool geometry and technological parameters. Experimental research has shown that increasing the punch indentation causes the material to flow in the transverse direction to the punch and the indirect extrusion in the region between the punches.

Metallic materials are widely employed in engineering constructions, and one of the most common failure mechanisms in metals is fatigue failure. Even though metal fatigue has been studied for almost 160 years, many problems remain unsolved. Fatigue in metal occurs when the metallic material is subjected to varying loads, resulting in failure due to damage accumulation. The fatigue process consists of a buildup of damage that leads to crack initiation, followed by a period of crack growth until the critical flaw size is reached. The sum of a start phase and a propagation phase represents the total life. To better understand the fatigue phenomenon at its different stages and predict the fatigue life, various types of prediction models have been developed and reported in the literature. This paper reviewed the different models that include microstructure scale parameters that can be used to predict how fatigue cracks start under variable amplitude loading, including the Modified Tanaka-Mura Model, Acoustic Second Harmonic Generation, and the Probability of Crack Initiation on Defects. For perfect life prediction under variable amplitude loading, a stress-based approach, a strain-based approach, and a continuum damage mechanics approach are reviewed. The purpose of this paper is to get overview of the current state of approaches to the life prediction of fatigue crack initiation with variable amplitude. Finally, gaps in knowledge about the prediction of fatigue crack initiation under variable loading at high temperatures are pointed out. [ABSTRACT FROM AUTHOR]

Globally, electricity demand rises by 1.8% per year; according to the American Energy Information Administration, global energy demand will increase by 47% over the next 30 years, driven by demographic and economic growth. Global demand for electricity is growing faster than renewable energy sources. Electricity production from renewable sources (i.e., biomass energy, geothermal energy, hydro energy, solar energy, tidal energy, wind energy) is on its way to strong growth around the world over the next dozen years. With the increasing demand for energy, new technologies and materials are being developed to replace exhaustible traditional construction materials. This article aims to provide a comprehensive overview of the research into the application of composite materials in mainstream power generation. The main energy generation technologies, i.e., photovoltaic panels, wind turbines, fuel cells, and biogas generators, were analysed and discussed. The review presented in this article also covers the latest achievements and prospects for the use of composite materials in energy generation devices. [ABSTRACT FROM AUTHOR]

Powder bed fusion (PBF) is recognized as one of the most common additive manufacturing technologies because of its attractive capability of fabricating complex geometries using many possible materials. However, the quality and reliability of parts produced by this technology are observed to be crucial aspects. In addition, the challenges of PBF-produced parts are hot issues among stakeholders because parts are still insufficient to meet the strict requirements of high-tech industries. This paper discusses the present state of the art in PBF and technological challenges, with a focus on selective laser melting (SLM). The review work focuses mainly on articles that emphasize the status and challenges of PBF metal-based AM, and the study is primarily limited to open-access sources, with special attention given to the process parameters and flaws as a determining factor for printed part quality and reliability. Moreover, the common defects due to an unstrained process parameter of SLM and those needed to monitor and sustain the quality and reliability of components are encompassed. From this review work, it has been observed that there are several factors, such as laser parameters, powder characteristics, material properties of powder and the printing chamber environments, that affect the SLM printing process and the mechanical properties of printed parts. It is also concluded that the SLM process is not only expensive and slow compared with conventional manufacturing processes, but it also suffers from key drawbacks, such as its reliability and quality in terms of dimensional accuracy, mechanical strength and surface roughness. [ABSTRACT FROM AUTHOR]

In the manufacturing process of innovative fiber-based composite materials, natural fibers are among the most commonly employed reinforcements. In this study, Enset/Sisal (E/S) fiber with a polyester matrix was used to develop the hybrid composites. Hand layup methods were employed for the sample preparation from untreated, 5%, and 10% alkali-treated unidirectional and woven fiber orientations having 50:50 volume ratios. The mechanical properties and water absorption of natural fiber hybrid composites were influenced by fiber treatment and orientation. In the present investigation, the result shows that treated and woven fiber orientation hybrid composites exhibit better mechanical properties than untreated and unidirectional E/S hybrid composites. The 5% NaOH-treated samples have higher tensile and flexural strength properties than the untreated and 10% alkali-treated composites, while the 5% NaOH-treated fiber composites have lower water absorption properties. The tensile and flexural strengths and impacts of 5% NaOH-treated composites were improved by 5.21%, 9.25%, and 5.98%, respectively, over untreated E/S hybrid composites. The morphological properties of the fracture surface of the composite were observed using scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

This study's objective is to review the literature on the environmental impact of the additive manufacturing process. When this new manufacturing technology is employed, it aims to create a healthy environment free of pollutants. The work is motivated by the lack of universal guidelines on new design approaches, the classification of manufacturing materials, and processes that address environmental concerns. Using additive manufacturing over traditional subtractive technologies may result in considerable material and energy resource savings, especially if the component is appropriately designed for manufacture. In this scenario, additive manufacturing, regarded as a potential breakthrough innovation, has grown in popularity in producing parts with complex geometry. AM encourages constant product development and flexible modifications that enable stakeholders to create better products faster. This study examines the state-of-the-art essentials of the fast-expanding manufacturing technique known as additive manufacturing (or 3D printing) and compares the environmental impact caused due to environmental issues. With increasing pressure on firms to provide transparency in their product sourcing and manufacturing processes, sustainability is no longer a distant goal but a strategic requirement. Manufacturers must also pay particular attention to their products' total energy usage and overall environmental impact. [ABSTRACT FROM AUTHOR]

Damaged support bores due to wear and ovality can be critical for a machine and its operation, in addition to representing a safety problem and risk of pin breakage. It can be a costly operation to perform the required repairs in between planned service periods, especially because of the unplanned down time. A joint with a standard cylindrical pin will often experience wear and ovality in the support bore surfaces, and at some point, repairs will have to be performed. This study investigates and compares five options when a joint with a cylindrical pin has reached a severe level of wear and ovality, outside its planned service stop. The work involved testing the viability of 3D scanning of the damaged bore surface, 3D printing of a metal bushing, and inserting the bushing into the damaged joint. In addition, two pin solutions, i.e., a standard cylindrical pin and an expanding pin type, were installed into the repaired joint, loaded, and the strain on the pin ends close to the supports was measured. For the sake of comparison, the supports had both smooth circular bore and severe wear and ovality. It was concluded that it is possible to produce and install the 3D-printed bushing insert without major problems; the insert had satisfactory capability during test loading, and it most probably represents a good solution when it comes to the reduction in unwanted downtime during unplanned repairs of damaged joints. [ABSTRACT FROM AUTHOR]

Aluminum alloy is the second most abundant metal on Earth, known for its wide range of utilization in commercial goods due to its heat capacity and tensile strength. This study examines the effect of nose radius on the turning process. Further, it explores the implications of cutting parameters such as the cutting speed, the rate of feed, the cutting depth, and the nose radius of the tool. The trials were carried out with an Al 6061 workpiece and an Al2O3-coated carbide tool as the cutter, utilizing the response surface methodology. A mathematical model was developed to investigate the performance characteristics of the turning operation using the analysis of variance method. The multi-response desirability function analysis combines individual desirability values to create a composite desirability value. The ideal parameter levels were determined using the composite desirability value, and the significant influence of parameters was assessed. The obtained optimum surface roughness and temperature parameters are at a cutting speed of 116.37 m/min, a rate of feed of 0.408 mm/rev, a cutting depth of 0.538 mm, and a tool nose radius of 0.20 mm. The related ideal surface roughness and temperature values are 0.374 µm and 27.439 °C. The optimal overall desirability value is 0.829, close to the target response. [ABSTRACT FROM AUTHOR]

Springback phenomenon affects the dimensional and geometrical accuracy of the bent parts. The prediction of springback is a key problem in sheet metal forming. The aim of this paper is the numerical analysis of the possibility to predict the springback of anisotropic steel sheets. The experiments are conducted on 40 x 100 mm steel sheets. The mechanical properties of the sheet metals have been determined through uniaxial tensile tests of samples cut along three directions with respect to the rolling direction. The numerical model of air V-bending is built in finite element method (FEM) based ABAQUS/Standard 2016.HF2 (Dassault Systemes Simulia Corp., USA) program. The FEM results were verified by experimental investigations. The simulation model has taken into consideration material anisotropy and strain hardening phenomenon. The results of FEM simulations confirmed the ability of numerical prediction of springback amount. It was also found that the directional microstructure of the sheet metal resulted from rolling process affects the elastic-plastic deformation of the sheets through the sample width.

The Markforged Metal X (MfMX) printing machine (Markforged Inc., Massachusetts, USA) is one of the latest introduced additive manufacturing (AM) devices. It is getting popular because of its safety, simplicity, and ability to utilize various types of powders/filaments for printing. Despite this, only a few papers have so far reported the various properties and performances of the components fabricated by the MfMX printer. In this study, the microstructure and mechanical properties of MfMX-fabricated 17-4 stainless steel (ss) in the as-printed and heat-treated conditions were investigated. XRD and microscopy analyses revealed a dominant martensitic microstructure with some retained austenite phase. The microstructure is generally characterized by patterned voids that were unfilled due to a lack of fusion between the adjacent filaments. Disregarding these defects (voids), the porosity of the dense region was less than 4%. Depending on the heat treatment conditions, the hardness and tensile strength were enhanced by 17–28% and 21–27%, respectively. However, the tensile strength analyzed in this work was low compared with some previous reports for L-PBF-fabricated 17-4 ss. In contrast, the hardness of the as-printed (331 ± 28 HV) and heat-treated samples under the H900 condition (417 ± 29 HV) were comparable with (and even better than) some reports in the literature, despite the low material density. The results generally indicated that the Markforged printer is a promising technology when the printing processes are fully developed and optimized. [ABSTRACT FROM AUTHOR]

The wind turbine blade is an important component for harnessing wind energy. It plays a vital role in wind turbine operation. In this work, a study was conducted to investigate the dynamic behavior of an optimal rotary wind turbine blade with a bond graph approach simulated with MATLAB/Simulink. The model is considered as a twisted Rayleigh beam which is made of several sections of the type SG6043 airfoil. This type of airfoil is suitable for low wind conditions, and each section is subjected to aerodynamic loads that are computed using the blade element momentum theory. The bond graph model was developed based on the law of conservation of mass and energy in the systems, and then the model was converted to the MATLAB/Simulink toolbox; results were validated with SG6043 airfoil data and real wind data collected from selected specific sites of Abomsa, Metehara, and Ziway areas in Ethiopia. [ABSTRACT FROM AUTHOR]

Composite Overwrapped Pressure Vessels (COPVs) are widely used in fields including aeronautics and by companies such as SpaceX to hold high pressure fluids. They are favored for these applications because they are far lighter than all-metal vessels, although they demand special design, manufacturing, and testing requirements. In this study, finite element modeling was used to conducted stress and damage assessments on a composite overwrapped pressure vessel that has a 4 mm thick aluminum core cylinder. To develop the optimum COPV, the lamina sequences, thickness, and fiber winding angle were considered. The relationship between these variables and the composite-overwrapped structure's maximum burst pressure bearing capacity was assessed. The ABAQUS composite modeler was used to design and generate 14 models of COPVs from carbon fiber/epoxy plies with a consistent thickness of 6.5 mm and various fiber angle orientations. The effects of the ply stacking order were analyzed by the finite element analysis approach for all designed models, which had 13 layers of uniform thickness but a varying fiber orientation. A ply stacking sequence of [55°, −55°] PP winding pattern had an optimum COPV design profile, with a burst pressure bearing capacity of 24 MPa. The stress–strain distribution along the geometry of the COPV was also obtained using the finite element method, and it was found that the distribution is uniform over the surface of the COPV and that its peak values are found towards the polar boss section of the COPV. Extreme stress gradients were noticed when the boss nears its geometrical transition to the dome phase. This factor is evident from the change in the ply thickness caused by the overlapped fiber orientation. The results obtained from this study are useful for the design and application of composite overwrapped pressure vessels. [ABSTRACT FROM AUTHOR]

Internal water pipe corrosion is a complicated problem due to the interaction of water quality parameters with the pipe wall. This study presents investigations of internal pipe surface corrosion mechanisms related to water physicochemical. Samples of water and corrosion-damaged ductile cast iron (30+ years) and galvanized steel pipe (15-20 years) were collected under in-situ condition from Addis Ababa city water distribution system. Scanning electron microscopy and optical microscopy were used to examine the pipes' corrosion morphology and microstructures, respectively. Additionally, Mountains 9 surface analysis software was used for further pitting corrosion characterization. To identify the causes of internal pipe corrosion, water physicochemical analyses were conducted by using inoLab pH 7310P, DR 900, Palintest Photometer 7100, and Miero 800. Water physicochemical test indicates: CaCO3 is 77-215 ppm, pH is 7.05 - 7.86, total dissolved solids (TDS) is 84.10-262.8 ppm, ClO2 is 0-0.5 ppm, and dissolved oxygen (80-81 ppb). From water test results, major causes of internal pipe corrosion damage mechanisms were identified as dissolved oxygen, CaCO3, TDS, ClO2,and resistivity of water which initiates a differential cell that accelerates pipe corrosion. Using Mountain 9 surface analysis software, corrosion morphology and pitting features were characterized. The outputs of this paper will be helpful for water distribution and buried infrastructure owners to investigate corrosion damage mechanisms at an early stage. To manage corrosion mechanisms, water supply owners need to conduct frequent inspections, recording of pipe data, testing of water quality, periodic pipelines washing, and apply preventative maintenance. [ABSTRACT FROM AUTHOR]

Due to their light weight, low density, high-specificity strength, and ease of fiber surface treatment, natural-fiber-reinforced composites are recognized as the most suitable materials for interior part applications. Moreover, natural fibers are widely accessible and environmentally friendly. The fabricated parts are assembled predominantly by fastening using drilled holes, which makes drilling operations common machining processes for the composite parts. Damage occurs at the entry and exit surfaces of drilled holes. In this study, hand layup procedures are used to create unidirectional and woven forms of 1:1 ratio enset (false banana)/sisal hybrid polyester composites that have been treated with 5% NaOH. The drill operation was performed using a computer numerical control (CNC) drill machine with high-speed steel twist drill. A Taguchi design tool was used to complete the analysis. The experiments were conducted at different levels of drilling speeds: 600, 1200, and 1800 rpm. Feed rates of 0.1, 0.2, and 0.3 mm/rev and drill bit diameters of 6, 9, and 12 mm were used. These were determined to be the study parameters that influenced the delamination factors (Fd) and surface roughness (SR) of the hybrid composite drilled parts. Delamination occurred at the entry and exit surfaces of the drilled holes, and surface roughness occurred at the inner surface of the sectioned drilled hole. The quality of the drilled holes was compared based on the delamination factor and the surface roughness, as analyzed by the 3D optical surface profiles. [ABSTRACT FROM AUTHOR]

In the present work, the study of fatigue failure of the disc brake of Volvo truck under thermomechanical effects across the disc thickness is reported. Both analytical and numerical approaches have been used. In the analytical approach, flat rigid asymmetric punch contact behavior was assumed at surface interaction, while in the numerical approach, the 3D finite element model of the vented disc type is subjected to thermomechanical cycles using ABAQUS software. Linear elastic material models were used to simulate the material's behavior under the applied pad pressure on the disc. Surface-to-surface type of contact was used for bodies that have arbitrary shapes with relatively large contact areas at disc pad interfaces. The crack initiated due to hydraulic pressure of 1.47 MPa on the disc was analyzed under mixedmode (mode I and II) conditions. This analysis has shown that the crack propagated up to critical length of 6.02 mm and finally, failure of the disc brake was observed. [ABSTRACT FROM AUTHOR]

An expanding pin locks the pin assembly to its supports and bearings and prevents any relative movements between the surfaces in contact. In this study, the diameter changes of the bearing inner ring as a function of the expanding pin's tightening torque were studied. In addition, the required rotational moment of a set of complete bearings locked to an expanding pin solution was studied by exposing the assembly to a combination of an increasing radially outwards directed load from the bolt torquing and a radially external inwards directed load from a hydraulic jack. The bearings were of type Radial Spherical Plain Bearings (RSPBs), GE 80 ES, steel/steel, and loaded externally up to their maximum dynamic limit of 400 kN. The results indicate a major reduction in the required rotation moment of the bearing when the bearing inner ring is expanded by use of an expanding pin. The reduction of rotation moment indicates reduced contact pressure and friction force between the two bearing rings, which ultimately can have a reduced effect on ring surface wear and a positive effect on the bearing operational lifetime. [ABSTRACT FROM AUTHOR]

Additive manufacturing, also known as three-dimensional printing, is a computer-controlled advanced manufacturing process that produces three-dimensional items by depositing materials directly from a computer-aided design model, usually in layers. Due to its capacity to manufacture complicated objects utilizing a wide range of materials with outstanding mechanical qualities, fused deposition modeling is one of the most commonly used additive manufacturing technologies. For printing high-quality components with appropriate mechanical qualities, such as tensile strength and flexural strength, the selection of adequate processing parameters is critical. Experimentally, the influence of process parameters such as the raster angle, printing orientation, air gap, raster width, and layer height on the tensile strength of fused deposition modeling printed items was examined in this work. Through analysis of variance, the impact of each parameter was measured and rated. The system's response was predicted using an adaptive neuro-fuzzy technique and an artificial neural network. In Minitab software, the Box-Behnken response surface experimental design was used to generate 46 experimental trials, which were then printed using acrylonitrile butadiene styrene polymer materials on a three-dimensional forge dreamer II fused deposition modelling printing machine. The results revealed that the raster angle, air gap, and raster width had significant impacts on the tensile strength. The adaptive neuro-fuzzy approach and artificial neural network predicted tensile strength accurately with an average percentage error of 0.0163 percent and 1.6437 percent, respectively. According to the findings, the model and experimental data are in good agreement. [ABSTRACT FROM AUTHOR]