Hasil untuk "Mechanical industries"

N. Aboulkhair, I. Maskery, C. Tuck et al.

Selective laser melting (SLM) of aluminium is of research interest because of its potential benefits to high value manufacturing applications in the aerospace and automotive industries. In order to demonstrate the credibility of SLM Al parts, their mechanical properties need to be studied. In this paper, the nano-, micro-, and macro-scale mechanical properties of SLM AlSi10Mg were examined. In addition, the effect of a conventional T6-like heat treatment was investigated and correlated to the generated microstructure. Nanoindentation showed uniform hardness within the SLM material. Significant spatial variation was observed after heat treatment due to phase transformation. It was found that the SLM material's micro-hardness exceeded its die-cast counterpart. Heat treatment softened the material, reducing micro-hardness from 125±1 HV to 100±1 HV. An ultimate tensile strength (333 MPa), surpassing that of the die cast counterpart was achieved, which was slightly reduced by heat treatment (12%) alongside a significant gain in strain-to-failure (~threefold). Significantly high compressive yield strength was recorded for the as-built material with the ability to withstand high compressive strains. The SLM characteristic microstructure yielded enhanced strength under loading, outperforming cast material. The use of a T6-like heat treatment procedure also modified the properties of the material to yield a potentially attractive compromise between the material's strength and ductility making it more suitable for a wider range of applications and opening up further opportunities for the additive manufacturing process and alloy combination.

Z. Ma, A. Feng, Daolun L. Chen et al.

T. A. Rodrigues, V. Duarte, J. Avila et al.

Abstract Wire and arc additive manufacturing (WAAM) is a viable technique for the manufacture of large and complex dedicated parts used in structural applications. High-strength low-alloy (HSLA) steels are well-known for their applications in the tool and die industries and as power-plant components. The microstructure and mechanical properties of the as-built parts are investigated, and are correlated with the thermal cycles involved in the process. The heat input is found to affect the cooling rates, interlayer temperatures, and residence times in the 800–500 °C interval when measured using an infrared camera. The microstructural characterization performed by scanning electron microscopy reveals that the microstructural constituents of the sample remain unchanged. i.e., the same microstructural constituents—ferrite, bainite, martensite, and retained austenite are present for all heat inputs. Electron backscattered diffraction analysis shows that no preferential texture has been developed in the samples. Because of the homogeneity in the microstructural features of the as-built parts, the mechanical properties of the as-built parts are found to be nearly isotropic. Mechanical testing of samples shows excellent ductility and high mechanical strength. This is the first study elucidating on the effect of thermal cycles on the microstructure and mechanical properties during WAAM of HSLA steel.

Xue Wang, Liping Zhao, J. Fuh et al.

Additive manufacturing (commonly known as 3D printing) is defined as a family of technologies that deposit and consolidate materials to create a 3D object as opposed to subtractive manufacturing methodologies. Fused deposition modeling (FDM), one of the most popular additive manufacturing techniques, has demonstrated extensive applications in various industries such as medical prosthetics, automotive, and aeronautics. As a thermal process, FDM may introduce internal voids and pores into the fabricated thermoplastics, giving rise to potential reduction on the mechanical properties. This paper aims to investigate the effects of the microscopic pores on the mechanical properties of material fabricated by the FDM process via experiments and micromechanical modeling. More specifically, the three-dimensional microscopic details of the internal pores, such as size, shape, density, and spatial location were quantitatively characterized by X-ray computed tomography (XCT) and, subsequently, experiments were conducted to characterize the mechanical properties of the material. Based on the microscopic details of the pores characterized by XCT, a micromechanical model was proposed to predict the mechanical properties of the material as a function of the porosity (ratio of total volume of the pores over total volume of the material). The prediction results of the mechanical properties were found to be in agreement with the experimental data as well as the existing works. The proposed micromechanical model allows the future designers to predict the elastic properties of the 3D printed material based on the porosity from XCT results. This provides a possibility of saving the experimental cost on destructive testing.

S. Chokshi, Vijay Parmar, P. Gohil et al.

ABSTRACT Natural Fiber (NF) becomes a vital part of the various industries such as textile, automotive, packaging, construction, etc. nowadays. This is a review of the chemical composition and mechanical properties of a wide variety of NFs including abaca fiber, bagasse fiber, bamboo fiber, banana fiber, coconut fiber, coir fiber, cotton fiber, flax fiber, hemp fiber, jute fiber, pineapple fiber, ramie fiber and sisal fiber. The chemical properties include cellulose, lignin, hemicellulose, pectin, wax, moisture, ash and microfibrillar angle. The physical properties include tensile strength (TS) and elastic modulus (E) and density (ρ). This paper discovers the significant ranges of chemical properties: cellulose, lignin, hemicellulose, pectin, wax, moisture, ash and microfibrillar angle and mechanical properties: tensile strength, elastic modulus and density.

Sharun Hegde, B. S. Shenoy, K. Chethan

Abstract Materials play a huge role in the shaping and development of human civilization. The need for materials started from the early stone-age where man needed fire to keep him warm and also to cook his food. Many materials such as copper, iron have been used in the past for few of the applications. But with the advancement of technology and new innovations brings about the need for lighter, more compact and many such other properties. So in order to fulfill these conditions a material such as composite material was developed. Carbon fiber Reinforced Polymer (CFRP) is a composite material which is very unique. CFRP has been widely used in aerospace industries. Slowly but gradually due to reduction in cost has lead it to be introduced in the automobile sector. The strength of the CFRP depends on the type of application, right combination of fiber to resin, length, type, orientation of fibers, use of anchors and form (sheet, plate). Temperature is an important factor which is taken into consideration. Curing of the adhesive at elevated temperatures and also if temperatures of the structures to which CFRP are bonded are kept below the glass transition temperature (Tg) it leads to longevity of the structure. CFRP is not affected by moisture by using non-reactive adhesive and in certain cases by treating the specimen with silane. The machinability of the CFRP specimens can be accomplished by using cold air, cryogenic environments and also by traditional methods with slight modifications. Hence it can be found useful in construction industry.

S. Nasiri, M. Khosravani

Abstract Although applications of additive manufacturing (AM) have been significantly increased in recent years, its broad application in several industries is still under progress. AM also known as three-dimensional (3D) printing is layer by layer manufacturing process which can be used for fabrication of geometrically complex customized functional end-use products. Since AM processing parameters have significant effects on the performance of the printed parts, it is necessary to tune these parameters which is a difficult task. Today, different artificial intelligence techniques have been utilized to optimize AM parameters and predict mechanical behavior of 3D-printed components. In the present study, applications of machine learning (ML) in prediction of structural performance and fracture of additively manufactured components has been presented. This study first outlines an overview of ML and then summarizes its applications in AM. The main part of this review, focuses on applications of ML in prediction of mechanical behavior and fracture of 3D-printed parts. To this aim, previous research works which investigated application of ML in characterization of polymeric and metallic 3D-printed parts have been reviewed and discussed. Moreover, the review and analysis indicate limitations, challenges, and perspectives for industrial applications of ML in the field of AM. Considering advantages of ML increase in applications of ML in optimization of 3D printing parameters, prediction of mechanical performance, and evaluation of 3D-printed products is expected.

L. Bai, X. Yue, Xiaohong Chen et al.

Abstract A porous lattice structure with highly controllable mechanical properties, low weight, and high strength is the most promising option for many fields, such as the aerospace, automobile, and biomedical industries. However, the most common and critical issue is the excessively high stress concentration at the struts’ nodes when the lattice structure is loaded. Thus, a curving lattice design strategy is proposed, maintaining a light structure, through which either a circular or elliptical arc is used in the lattice struts to obtain new forms of curving lattice structures. By establishing theoretical models and preparing samples by laser powder bed fusion (L-PBF), combined with scanning electron microscopy (SEM), quasi-static uniaxial compressive experiments, finite element analysis (FEA), and Gibson-Ashby models, excellent results were obtained. The stress distribution of the original under the loads was altered in the curving lattice structure and the stress concentration at the nodes of the struts was effectively relieved, dramatically improving its mechanical properties. Compared with the original structure, the specific elastic modulus and specific compressive strength of curving lattice structures were maximally increased by 213.7% and 126.2%, respectively. Meanwhile, the curving lattice structure had a superior energy absorption capacity, with a significant increase of 92.9%.

M. Bashir

Dynamic mechanical analysis (DMA) provides reliable information about the viscoelastic behavior of neat and filled polymers. The properties of filled polymers are relevant to different industries as protective organic coatings, composites etc. Interfacial interactions in filled polymers play an important role in determining their bulk properties and performance during service life. In this brief review article, studies that used DMA to characterize the interfacial interactions in filled polymers have been reviewed. The available open literature provides a mixed opinion about the influence of interfacial interactions on the glass transition temperature of filled polymers. Nevertheless, it appears that in the case of strong interfacial interactions between the filler particles and the polymeric matrix, the peak value of tan δ is reduced in comparison to that of a filled polymer where these interactions are weak.

Prerna Mishra, Vivek Gupta, Prateek Deoman Malwe et al.

Abstract Ratcheting fatigue behavior is a critical phenomenon in structural materials undergoing cyclic loading, particularly when combined with nonzero mean stress or multiaxial stress states. This manifests as the progressive buildup of plastic strain in one direction with each loading cycle, ultimately leading to material degradation and failure. This behavior is highly relevant in industries such as automotive, aerospace, nuclear, and civil engineering, where components frequently experience complex loading conditions. Structural materials exposed to ratcheting fatigue often exhibit changes in their mechanical properties, such as cyclic hardening or softening, which influence their ability to withstand cyclic stresses. Factors such as the mean stress, stress amplitude, loading path, material microstructure, and environmental conditions play crucial roles in governing the ratcheting response. Understanding the ratcheting fatigue behavior is essential for the design and life prediction of critical components. Comprehensive investigations through experimental testing and computational modelling are required. This investigation presents the asymmetrical stress-controlled (ratcheting) behaviour of 9 C-1Mo modified steel and IN-617 superalloy at service temperatures of 600 and 800oC respectively at different tensile mean stresses. When there was change in the mean stress, the amplitude of stress as well as the rate of stress was not changed. The fatigue life of these alloys decreased with an increase in tensile mean stress. The maximum stress increases with the mean stress and leads to a higher inducement of the plastic strain, which results in a lower fatigue life. At elevated temperatures, the fatigue life was found to be higher than that at room temperature (RT) owing to dynamic-strain aging.

Shahjadi Hisan Farjana, N. Huda, M. Mahmud et al.

This paper analysed and summarised the significant research outputs published on the environmental impact assessment of mining and mineral processing industries through life cycle assessment. The paper presents valuable insights in identifying the gaps, where should the focus be in the mining and mineral processing industries for a sustainable future. Mining and mineral processing industries have been the key focus of research in many countries due to its increasing sustainability concerns that affect global warming and climate change. Use of heavy equipment that consumes electrical energy, mechanical energy, and an enormous amount of process heat is a key contributor to the overall impacts in the industry. Due to the use of heavy equipment and associated energy consumption, these industrial sectors contribute notably to global warming, human health, ecosystems, and resources. Among the various environmental impact assessment tools which are widely used to identify sustainability indicators, life cycle assessment (LCA) is a well-justified approach among the practitioners and researchers. Though state of the art technological tools and resources are being used now a days, there is still a research gap in identifying the key mining processes which need to be the focus of attention. Renewable energy integration in the mineral processing sector and process heating from green energy sources is becoming the emergent field of research. The review results reveal, the assessment indicators in human health and ecosystems are key factors that are mostly missing in the previous studies which are crucial for people or community living nearby mining area. This review paper identifies the research gaps to the existing literature that can form the base for future research direction in the field of LCA and sustainable energy integration in mining and mineral processing industries.

Wenxiang Xie, Zhenyu Zhang, Longxing Liao et al.

Toxic and corrosive solutions are widely used in the preparation of abrasives and chemical mechanical polishing (CMP) of sapphire wafers, resulting in potential environmental pollution. Developing a novel green CMP technique to achieve light-emitting diode sapphire wafers is a significant challenge. In this study, a novel green CMP slurry, consisting of silica, sorbitol, aminomethyl propanol, and deionized water was developed for sapphire wafers. After CMP, the sapphire wafers were cleaned with deionized water and dried with compressed air, which is a green process. After CMP, the surface roughness Ra of the sapphire wafer surface with an area of 5 × 5 μm2 was 0.098 nm, which is the lowest surface roughness reported to date for sapphire wafers. Tetrahydroxy-coordinated Al(OH)4- ions were produced in the alkaline CMP slurry, and chelation occurred between sorbitol and these ions. The proposed green CMP has potential applications in the semiconductor and microelectronics industries.

Y. Lei, Z. Wang, Bo Zhang et al.

Stainless steels with high mechanical properties and corrosion resistance are promising structural materials for the next generation of aerospace and some niche industries. In this work, we pre-formed a gradient nanostructured (GNS) surface layer on 316L stainless steel by surface mechanical rolling treatment (SMRT) and subsequently annealed it at 700 °C. Tensile tests showed that the strength-ductility synergy was enhanced in the annealed-SMRT sample, while the grain size and hardness in the GNS layer retained rather stable. In addition, a remarkable Cr-enrichment was found in the GNS surface layer after annealing, resulting in a significantly enhanced corrosion resistance. The underlying mechanisms on the microstructure, composition and phases evolutions, as well as their effects on deformation and corrosion behavior, were analyzed in the annealed-SMRT sample. This work provides insights on developing a simple thermomechanical approach to produce stainless steels with enhanced mechanical properties and corrosion resistance.

P. Ponnusamy, R. R. Rahman Rashid, S. Masood et al.

Selective laser melting (SLM) is a powder bed fusion type metal additive manufacturing process which is being applied to manufacture highly customised and value-added parts in biomedical, defence, aerospace, and automotive industries. Aluminium alloy is one of the widely used metals in manufacturing parts in SLM in these sectors due to its light weight, high strength, and corrosion resistance properties. Parts used in such applications can be subjected to severe dynamic loadings and high temperature conditions in service. It is important to understand the mechanical response of such products produced by SLM under different loading and operating conditions. This paper presents a comprehensive review of the latest research carried out in understanding the mechanical properties of aluminium alloys processed by SLM under static, dynamic, different build orientations, and heat treatment conditions with the aim of identifying research gaps and future research directions.

A. Pistone, C. Scolaro, A. Visco

The accumulation of marine organisms on ship hulls, such as microorganisms, barnacles, and seaweeds, represents a global problem for maritime industries, with both economic and environmental costs. The use of biocide-containing paints poses a serious threat to marine ecosystems, affecting both target and non-target organisms driving science and technology towards non-biocidal solutions based on physico-chemical and materials properties of coatings. The review reports recent development of hydrophobic protective coatings in terms of mechanical properties, correlated with the wet ability features. The attention is focused mainly on coatings based on siloxane and epoxy resin due to the wide application fields of such systems in the marine industry. Polyurethane and other systems have been considered as well. These coatings for anti-fouling applications needs to be both long-term mechanically stable, perfectly adherent with the metallic/composite substrate, and capable to detach/destroy the fouling organism. Prospects should focus on developing even “greener” antifouling coatings solutions. These coatings should also be readily addressable to industrial scale-up for large-scale product distribution, possibly at a reasonable cost.

I. Akande, O. Oluwole, O. Fayomi et al.

Abstract This review paper examined the mechanical, microstructural, corrosion properties, high-temperature applications (HTAs) and protective measures that have been applied for optimal performance of superalloys. The quest for materials with excellent characteristics necessitated the development of superalloys over the years. Superalloys are class of nickel (Ni), cobalt (Co) and iron (Fe) based alloys used in jet and marine turbine engines due to their outstanding dimensional stability at a much higher temperature compared to most structural and high-temperature materials. Superalloys can use a high fraction of their melting point, and this positioned them in the category of high-temperature application materials. They are also reported to exhibit reasonable corrosion resistance and good mechanical properties even at elevated temperature, which facilitates their suitability for high-stress manufacturing and advance applications, such as in the production of turbine engines for the marine and aerospace industries. The surface of superalloys can be protected using diffusion, overlaying and thermal barrier coatings (TBCs), which act as a barrier against oxidation, corrosion, depletion in microstructure and thermal deformation.

J. Pires, Camila Damásio de Paula, V. G. Souza et al.

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties.

Сергій Орищенко, Віктор Орищенко

Під час робочого процесу навантажувач перемішується на майже горизонтальних майданчиках, допустимий ухил яких. Розрахунок поздовжньої стійкості навантажувачів ведеться з умови перекидання вперед з урахуванням того, що деформуються пневматичні шини, якщо пневмоколісний хід. Кут додаткового нахилу навантажувача вперед внаслідок деформації опор визначається співвідношенням сили тяжкості навантажувача з вантажем жорсткість ґрунту під переднім та заднім котками гусеничного ходу або радіальна жорсткість передніх та задніх пневматичних шин навантажувача на пневмоколісному ході; відстань між центром ваги навантажувача та вертикальною віссю, що проходить через точку перекидання. Тому при розрахунку поздовжньої стійкості гусеничного та пневмоколісного навантажувачів. Найменший запас поздовжньої стійкості має навантажувач у разі руху під ухил з одночасним гальмуванням машини та робочого обладнання при його опусканні. Положення робочого обладнання відповідає максимальному вильоту.

Amal Nassar, Eman Nassar, Ivan Rivilla et al.

A phase-change material (PCM) is recommended for thermal energy storage. However, conventional PCMs suffer from poor thermal conductivity. To solve this problem, this study presented different compositions to improve PCM thermal conductivity. The effects of the average specific surface of metal foams and the weight percentage of metal foams and hybrid nanoparticles on the phase-change materials' thermal characteristics were investigated. The findings demonstrate that thermal performance of the PCM composite is noticeably better than that of pure PCM and increasing the weight content of foam metal and hybrid nanoparticles leads to an increase in thermal conductivity of 37.7% for the same type of copper. The results also reveal that thermal conductivity performance increases as the amount of metal foam and hybrid nanoparticles increases. The average specific surface value of 1600 m2/m3 shows better thermal properties compared with other average specific surface values. Moreover, the heat capacity is affected by the increase in the content of metal foam. Many drawbacks have been found in using foam metal in PCM preparation, mainly the fixed shapes of metal foams compared with the formability nature of the PCM, which effects the shapes of the PCM composites and thus limits its use in applications with limited size. This novel approach to improving PCM's thermal behaviour may be applied to the creation of thermal energy storage devices with predetermined characteristics.

Oleksandr Diachenko, Maksym Delembovskyi, Kateryna Levchuk et al.

The production of concrete mixes, along with their use in the production of building materials and structures, is one of the key processes in the construction industry during the construction, restoration and repair of buildings and structures. Because of this, the need to create modern concrete mixing plants that will meet the requirements of minimum energy consumption and maximum productivity of concrete mixture production is an urgent task. Not only the main operations, which include the dosing of the components of the mixture and their mixing, but also the maintenance operations, namely operations that ensure the timely movement of the components of the concrete mixture from warehouses to the main technological equipment, affect the set rhythm of the concrete mixture production. Conveyors of various types and designs are used to move bulk materials, such as crushed stone and sand. For the rational selection of such equipment in accordance with the characteristics of the cargo to be transported, knowledge of the types of conveyors, their structures and parameters, understanding of operation issues and methods of parameter calculation are required. In addition, it is worth paying attention to the following parameters: maximum cargo transportation productivity, low energy consumption per unit of moved products, low metal content of the structure. The work reviewed the most common designs of conveyors used to move bulk materials in concrete mixing plants, analyzed the disadvantages and advantages of conveyors, as well as technical parameters. As a result, the predominant directions for the use of belt and plate conveyors at construction enterprises were determined. The advantages of belt conveyors, which contribute to their widespread distribution, are high productivity, simplicity of design, reliability, quiet operation, low specific power consumption. When choosing a conveyor, it is recommended to choose the equipment with the highest productivity and the lowest power of the drive motors, however, the performance should be clearly related to other technological equipment.