Hasil untuk "Mechanical industries"

Shady Farah, Daniel G. Anderson, R. Langer

Poly(lactic acid) (PLA), so far, is the most extensively researched and utilized biodegradable aliphatic polyester in human history. Due to its merits, PLA is a leading biomaterial for numerous applications in medicine as well as in industry replacing conventional petrochemical-based polymers. The main purpose of this review is to elaborate the mechanical and physical properties that affect its stability, processability, degradation, PLA-other polymers immiscibility, aging and recyclability, and therefore its potential suitability to fulfill specific application requirements. This review also summarizes variations in these properties during PLA processing (i.e. thermal degradation and recyclability), biodegradation, packaging and sterilization, and aging (i.e. weathering and hygrothermal). In addition, we discuss up-to-date strategies for PLA properties improvements including components and plasticizer blending, nucleation agent addition, and PLA modifications and nanoformulations. Incorporating better understanding of the role of these properties with available improvement strategies is the key for successful utilization of PLA and its copolymers/composites/blends to maximize their fit with worldwide application needs.

Hao Chen, M. Ling, Luke Hencz et al.

Tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. However, binders, as an important component of energy-storage devices, are yet to receive similar attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. To address these concerns, in this review we divide the binding between active materials and binders into two major mechanisms: mechanical interlocking and interfacial binding forces. We review existing and emerging binders, binding technology used in energy-storage devices (including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and supercapacitors), and state-of-the-art mechanical characterization and computational methods for binder research. Finally, we propose prospective next-generation binders for energy-storage devices from the molecular level to the macro level. Functional binders will play crucial roles in future high-performance energy-storage devices.

Amer Hassan, M. Arif, M. Shariq

Abstract Geopolymer concrete (GPC) has been researched during the past few decades as an alternative to sustainable construction materials, which can minimize CO2 emission for its use of industry by-products. Past researches on GPC show that it can be suitable for the structural applications, with a workable slump, and comparable grade of strength to ordinary Portland cement concrete. In this review paper, the mix design, mechanical properties, durability and microstructure of GPC have been discussed to figure out and report the last data and information regarding geopolymer concrete. In addition to that, the microstructure of GPC and OPC concrete have been investigated to understand the internal structure of GPC and evaluate its engineering properties such as strength and durability etc. Review of literature revealed that the production of geopolymer concrete requires great care and correct material composition. During the activation process in making the geopolymer, high alkalinity also requires safety risk and enhanced energy consumption and generation of greenhouse gases. Furthermore, the production of GPC is also affected by the curing time and curing temperature. Therefore, there is an urgent need to develop user-friendly design geopolymer concrete procedure/code that can be used in a variety of construction areas. In summary, this literature review offers guidance for civil engineers and industrial community in future researches regarding geopolymer concrete.

Te Han, Chao Liu, Wenguang Yang et al.

Abstract In recent years, deep learning has become an emerging research orientation in the field of intelligent monitoring and fault diagnosis for industry equipment. Generally, the success of supervised deep models is largely attributed to a mass of typically labeled data, while it is often limited in real diagnosis tasks. In addition, the diagnostic model trained with data from limited conditions may generalize poorly for conditions not observed during training. To tackle these challenges, adversarial learning is introduced as a regularization into the convolutional neural network (CNN), and a novel deep adversarial convolutional neural network (DACNN) is accordingly proposed in this paper. By adding an additional discriminative classifier, an adversarial learning framework can be developed to train the convolutional blocks with the split data subsets, leading to a minimax two-player game. This process contributes to making the feature representation robust, boosting the generalization ability of the trained model as well as avoiding overfitting with a small size of labeled samples. The comparison studies with respect to conventional deep models on two fault datasets demonstrate the applicability and superiority of proposed method.

Tianqiao Liu, Xing-zhan Liu, P. Feng

Abstract Pultruded fiber-reinforced polymer (FRP) composite is expected to be widely applied for civil infrastructures due to its advantages of lightweight, anti-corrosion, and industrial manufacturing. Its long-term performance has attracted increasing attentions from academia and industry. This paper presents a comprehensive review on experimental studies investigating the mechanical performance of pultruded FRP composites subjected to long-term environmental effects, including water/moisture, alkaline solutions, acidic solutions, low/high temperatures, ultraviolet radiation, freeze-thaw cycles, wet-dry cycles, and in situ environments. Over 1900 experimentally determined mechanical properties of FRP materials were collected, including tensile, compressive, flexural and shear strength and moduli. The reported test data were highly dispersed, and no uniform conclusions could be drawn from these data. Exposure to water and water-based solutions (alkaline and acidic solutions) had detrimental impacts on the mechanical properties of pultruded FRP materials, whereas other environmental effects induced various levels of degradation. The degradation mechanisms for each environmental effect were discussed, and the existing design approaches were presented. Based on the findings from this review, recommendations were proposed for future works. The database presented herein, which is the largest in the available literature, enables a comprehensive understanding of the degradation behavior of pultruded FRP composites. Moreover, this work can serve as a foundation for deriving predictive models for pultruded FRP materials exposed to long-term environmental effects.

R. Roychand, R. Gravina, Y. Zhuge et al.

Abstract Recycling of ‘End of Life Tyres’ (ELT) is one of the major environmental concerns faced by the scientific community and the government organisations, worldwide. Every year, an estimated one billion tyres reach their end of life, out of which only about 50% are currently being recycled and the remaining form part of the landfills. Therefore, there is an urgent need to improve the existing and develop new applications of recycled tyre products to address this shortfall in the utilisation rate of the ELT. One application which is actively being researched is the use of waste tyre rubber as a partial replacement of conventional aggregates in concrete applications. Although it shows tremendous potential, it comes with its own challenges such as weak inherent strength of the rubber and poor bond performance with the cement matrix, which hinders its use as an aggregate in large quantities. To overcome this challenge, researchers have looked at various rubber treatment methods that not only improve the bond performance but also significantly improve the mechanical properties of rubber concrete. This review paper considers the effect of rubber particle size, percentage replacement and various treatment methods on different mechanical properties of rubber concrete, studied over the last 30 years. However, to be accepted by the concrete industry, the researchers have to come up with a rubber treatment method that can address the concerns of high flammability and the resultant release of noxious gases from the rubber particles, when exposed to fire.

Lei Yang, R. Mertens, M. Ferrucci et al.

Abstract Functional graded cellular materials (FGCMs) have attracted increasing attentions for their improved properties when compared to uniform cellular structures. In this work, graded Gyroid cellular structures (GCSs) with varying gradient directions were designed and manufactured via selective laser melting (SLM). As a reference, uniform structures were also manufactured. The surface morphology and mechanical response of these structures under compressive loads were investigated. Results indicate high manufacturability and repeatability of GCSs manufactured by SLM. Optimized density distribution gives these structures novel deformation and mechanical properties. GCSs with density gradient perpendicular to the loading direction exhibit deformation behaviours similar to uniform ones, while GCSs with the gradient parallel to the loading direction exhibit layer-by-layer deformation and collapse behaviour. A novel phenomenon of sub-layer collapses is found in GCSs with gradient parallel to the loading direction. Furthermore, mathematical models were developed to predict and customize the mechanical properties of graded cellular structures by optimizing the relative density of each layer. These significant findings illustrate that graded cellular structures have high application prospect in various industries, particularly given the fact that additive manufacturing has been an enabler of cellular structure fabrication.

Xiaoyu Zhang, Li Tang, Jiusheng Chen

The electro-mechanical actuators (EMAs) play an important role in the new-generation aircraft, which makes the fault diagnosis of EMA become a hot topic in the industry. However, the EMA signals usually have nonlinear characteristics and seasonal tendency, which bring great challenge to the fault diagnosis. Furthermore, detecting faults in the early stage helps reduce the risk of serious damage to EMA, but most studies are focusing on the situation that the EMA faults are well-developed. To tackle the challenge, we present an innovative algorithm which combines a hybrid-spatial and temporal attention-based gated recurrent unit (HSTA-GRU) with Seasonal-Trend decomposition procedures based on Loess (STL) to predict multiple time-series data for more failure information. The STL extracts the seasonal factor for mitigating the influence of seasonal fluctuation, and the HSTA-GRU captures the spatio-temporal relationships among multivariate EMA sensors for a long-term prediction of multiple time-series data. Then, for the predicted time series, a similarity measure (SM) function based on dynamic time warping (DTW) is used to classify the fault types without training, so as to reduce the accumulated error and enhance the efficiency of classification. Ultimately, the analysis result on an experimental EMA fault dataset demonstrates that the proposed arithmetic can provide a superior performance not only in the time series prediction, but also for EMA fault diagnosis.

Abdullah Sayam, A. Rahman, Md. Sakibur Rahman et al.

The utilization of carbonaceous reinforcement-based polymer matrix composites in structural applications has become a hot topic in composite research. Although conventional carbon fiber-reinforced polymer composites (CFRPs) have revolutionized the composite industry by offering unparalleled features, they are often plagued with a weak interface and lack of toughness. However, the promising aspects of carbon fiber-based fiber hybrid composites and hierarchical composites can compensate for these setbacks. This review provides a meticulous landscape and recent progress of polymer matrix-based different carbonaceous (carbon fiber, carbon nanotube, graphene, and nanodiamond) fillers reinforced composites’ mechanical properties. First, the mechanical performance of neat CFRP was exhaustively analyzed, attributing parameters were listed down, and CFRPs’ mechanical performance barriers were clearly outlined. Here, short carbon fiber-reinforced thermoplastic composite was distinguished as a prospective material. Second, the strategic advantages of fiber hybrid composites over conventional CFRP were elucidated. Third, the mechanical performance of hierarchical composites based on carbon nanotube (1D), graphene (2D) and nanodiamond (0D) was expounded and evaluated against neat CFRP. Fourth, the review comprehensively discussed different fabrication methods, categorized them according to performance and suggested potential future directions. From here, the review sorted out three-dimensional printing (3DP) as the most futuristic fabrication method and thoroughly delivered its pros and cons in the context of the aforementioned carbonaceous materials. To conclude, the structural applications, current challenges and future prospects pertinent to these carbonaceous fillers reinforced composite materials were elaborated.

N. M. Nurazzi, F. A. Sabaruddin, M. M. Harussani et al.

Developments in the synthesis and scalable manufacturing of carbon nanomaterials like carbon nanotubes (CNTs) have been widely used in the polymer material industry over the last few decades, resulting in a series of fascinating multifunctional composites used in fields ranging from portable electronic devices, entertainment and sports to the military, aerospace, and automotive sectors. CNTs offer good thermal and electrical properties, as well as a low density and a high Young’s modulus, making them suitable nanofillers for polymer composites. As mechanical reinforcements for structural applications CNTs are unique due to their nano-dimensions and size, as well as their incredible strength. Although a large number of studies have been conducted on these novel materials, there have only been a few reviews published on their mechanical performance in polymer composites. As a result, in this review we have covered some of the key application factors as well as the mechanical properties of CNTs-reinforced polymer composites. Finally, the potential uses of CNTs hybridised with polymer composites reinforced with natural fibres such as kenaf fibre, oil palm empty fruit bunch (OPEFB) fibre, bamboo fibre, and sugar palm fibre have been highlighted.

S. C. Devi, R. Khan

Abstract Graphene oxide (GO) may have a huge impact in construction industry in near future. Because of the oxygenated functionalities attached on the aromatic structure, it has better dispersibility property than any other graphene-based derived. Many of the researchers have given their views on the influence of GO on the mechanical and durability properties in ceramic matrix. Five mixes were prepared with inclusion of GO (0%, 0.02%, 0.04%, 0.06% and 0.08% by weight of cement). Tests on mechanical and water permeation properties were conducted. The compressive and tensile strength of the mix with 0.08% GO has shown a better result compared to rest of the mixes. The sorptivity and permeability of the nano-reinforced concrete mixes in addition of GO were observed to have reduced with increasing GO content in the concrete compared to the control mix. The synthesized GO was structurally characterized by means of FE-SEM/EDX, FT-IR and XRD. Microstructural analysis was carried out using SEM/EDX on 90 days old concrete mixes and the quality of the concrete mixes was checked with UPV test.

Shubin Wang, Ming. H. Wu, D. Shu et al.

Abstract The equiatomic TiZrHfNbTa alloy is one of the few refractory high entropy alloys that exhibit tensile ductility at room temperature, the deformation of which is only dominated by dislocation slip. Here, we observed the activation of {112} nano-twinning accompanied by the deformation induced body-centered cubic structure (BCC) to non-closed packed hexagonal ω phase transformation along with the dislocation slip during tensile deformation at cryogenic temperatures, which indicates the intrinsic mechanical instability of the single-phase BCC TiZrHfNbTa solid solution. The alloy maintains a high tensile elongation of 20.8% while the yield strength increases significantly up to 1,549 MPa as the temperature is decreased from 277 K to 77 K, without obvious ductile to brittle transition. This exceptional combination of high strength and high ductility at cryogenic temperatures can be interpreted by considering the synergistic effect of screw dislocation glide, {112} mechanical twinning and BCC → ω phase transformation. These results provide new insights on our understanding of the refractory TiZrHfNbTa-based alloys and extend their application to cryogenic temperatures at the extreme service conditions like aerospace, marine shipbuilding and natural gas industries, albeit they are promising for high-temperature application.

Xue Bi, Hang Di, Jia Liu et al.

J. Y. Boey, Chee Keong Lee, G. Tay

The short life cycle and recalcitrant nature of petroleum-based plastics have been associated with plastic waste accumulation due to their composition rather than worldwide overproduction. The drive to replace single-use products has sparked a considerable amount of research work to discover sustainable options for petroleum-based plastics. Bioplastics open up a new horizon in plastics manufacturing operations and industrial sectors because of their low environmental impact, superior biodegradability, and contribution to sustainable goals. Their mechanical properties regarding tensile, flexural, hardness, and impact strength vary substantially. Various attempts have been made to augment their mechanical characteristics and capacities by incorporating reinforcement materials, such as inorganic and lignocellulosic fibres. This review summarizes the research on the properties of bioplastics modified by fibre reinforcement, with a focus on mechanical performance. The mechanical properties of reinforced bioplastics are significantly driven by parameters such as filler type, filler percentage, and aspect ratio. Fibre treatment aims to promote fibre–matrix adhesion by changing their physical, chemical, thermal, and mechanical properties. A general overview of how different filler treatments affect the mechanical properties of the composite is also presented. Lastly, the application of natural fibre-reinforced bioplastics in the automobile, construction, and packaging industries is discussed.

A. Akhnoukh, Chelsea Buckhalter

Abstract Ultra-high-performance concrete (UHPC) is a new class of concrete developed in France in the 1990s with superior characteristics including high workability, high compressive strength, increased ductility, and high resistance to environmental attacks. UHPC is increasingly used in local and international construction markets in the construction of high rise structures, long-span precast/prestressed bridge girders, marine, aviation, and defense construction applications due to its superior mechanical properties, and favorable long-term performance. This study presents recent research findings regarding the UHPC mix designs, fresh and hardened concrete properties, and current UHPC applications in the construction industry including specific bridge applications. Despite of UHPC advantages, multiple impediments are present that delays the widespread of UHPC application in the construction industry including lack of design codes and specifications for estimating UHPC performance, the need for special batching, mixing, and curing. This study assists different construction stakeholders in understanding the unique characteristics, advantages, and impediments to the widespread of UHPC applications. The deciphering of UHPC will help increase its overall market share in local and global construction markets.

Yu Lu, Qi Zhang, Yukai Chen et al.

Metal additive manufacturing (AM) holds significant potential for the rapid prototyping of complex parts in the aerospace, defense, and military industries, biomedicine, and other fields. Despite its advantages over conventional manufacturing methods, AM faces technical bottlenecks (e.g., poor densification, high residual stress, and significant anisotropy of mechanical properties), which hinder its large-scale industrial application. The newly emerging metal hybrid additive manufacturing (MHAM) serves as a viable approach to address the inherent issues associated with AM. This method integrates different auxiliary technologies (e.g., subtractive manufacturing, formative manufacturing, magnetic fields, ultrasonic fields, thermal fields, etc.), leveraging the strengths of these technologies to enhance the performance of metal components produced via AM. MHAM offers numerous advantages, such as controlling the flow of the melt pool, refining the microstructure, optimizing the grain size orientation, reducing the residual stress, enhancing the surface quality, and improving the mechanical properties and fatigue resistance. This work offers a thorough and current analysis of the state of MHAM development, including additive and subtractive hybrid manufacturing, additive and formative hybrid manufacturing, and energy field-assisted additive manufacturing. It delineates the MHAM technology framework and clarifies the interaction mechanisms among various auxiliary technologies used in AM. Additionally, it discusses the impacts of MHAM on melt pool dynamics, solidification processes, densification, microstructure evolution, surface quality, and mechanical and fatigue properties. In summary, the distinct characteristics of various MHAM techniques are outlined, and future trends in MHAM development are anticipated.

Zhenyu Zhang, L. Jie, Wei Hu et al.

Abstract At present, corrosive ingredients are widely employed in chemical mechanical polishing (CMP) of sapphire, bringing a potential threat to both people and environment. This results in high cost and long processing time on the treatment of CMP slurry of sapphire. It is a challenge to develop a novel green CMP for sapphire to meet the stringent requirements of high performance products. In this study, a novel green CMP is proposed for sapphire, consisting of silica nanoparticles of 50 nm, triethanolamine (TEA), sodium metasilicate nonahydrate, and deionized water. After green CMP, surface roughness Ra, root mean square (rms), and peak-to-valley (PV) are 0.11, 0.139, and 1.65 nm, respectively. Material removal rate is 3.31 μm/h during green CMP. To the best of our knowledge, surface roughness Ra and rms after green CMP developed are the lowest on a sapphire wafer, compared with those reported previously. The CMP mechanism is elucidated by X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectra. Sapphire formed Al(OH)4− ions in an alkaline environment, which was chelated by TEA, and removed from the surface of sapphire. These findings provide new insights to fabricate high performance devices of sapphire for the use in semiconductor and microelectronic industries.

Virat Khanna, Vanish Kumar, S. Bansal

Abstract Fast advancements in the mechanical industry constantly place a demand for new and dependable materials. Metal matrix composites (MMCs) are one of the most prominent candidates to perform indispensable jobs in the mechanical industry. In particular, carbon nanostructures, e.g., graphene and carbon nanotubes (CNTs) are found as excellent support reinforcement materials in MMCs. This review article focuses on graphene/CNTs reinforcement in aluminium (Al), the third-most abundant metal on earth, for improvement in mechanical properties. The article evaluates the impact of graphene/CNTs reinforcement in the Al matrix based on key parameters, e.g., yield strength, microhardness, ductilityand tensile strength. Moreover, different Al-graphene/CNTs processing (primary and secondary) methods have been reviewed.

Manvendra Verma, Nirendra Dev, I. Rahman et al.

Geopolymer concrete (GPC) is a new material in the construction industry, with different chemical compositions and reactions involved in a binding material. The pozzolanic materials (industrial waste like fly ash, ground granulated blast furnace slag (GGBFS), and rice husk ash), which contain high silica and alumina, work as binding materials in the mix. Geopolymer concrete is economical, low energy consumption, thermally stable, easily workable, eco-friendly, cementless, and durable. GPC reduces carbon footprints by using industrial solid waste like slag, fly ash, and rice husk ash. Around one tonne of carbon dioxide emissions produced one tonne of cement that directly polluted the environment and increased the world’s temperature by increasing greenhouse gas production. For sustainable construction, GPC reduces the use of cement and finds the alternative of cement for the material’s binding property. So, the geopolymer concrete is an alternative to Portland cement concrete and it is a potential material having large commercial value and for sustainable development in Indian construction industries. The comprehensive survey of the literature shows that geopolymer concrete is a perfect alternative to Portland cement concrete because it has better physical, mechanical, and durable properties. Geopolymer concrete is highly resistant to acid, sulphate, and salt attack. Geopolymer concrete plays a vital role in the construction industry through its use in bridge construction, high-rise buildings, highways, tunnels, dams, and hydraulic structures, because of its high performance. It can be concluded from the review that sustainable development is achieved by employing geopolymers in Indian construction industries, because it results in lower CO2 emissions, optimum utilization of natural resources, utilization of waste materials, is more cost-effective in long life infrastructure construction, and, socially, in financial benefits and employment generation.

Jiang Xu, Haoxiang Qu

Iconic products, as innovative carriers supporting the development of future industries, are key breakthrough points for driving the transformation of new quality productive forces. This article is grounded in the philosophy of technology and examines the evolution of human civilization to accurately identify the patterns of product innovation. By integrating theories from systems science, it analyzes the intrinsic logical differences between traditional products and iconic products. The study finds that iconic products are based on a comprehensive knowledge system that integrates explicit and tacit knowledge, enabling them to adapt to complex dynamic environments. Therefore, based on the method of phenomenological essence reduction and the process of specialized knowledge acquisition, this study establishes the first principle of knowledge phenomenology: "knowledge generation-moving from the tacit to the explicit-moving from the explicit to the tacit-fusion of the explicit and tacit." Grounded in knowledge phenomenology, it reconstructs the product design evolution process and establishes a forward innovative design framework for iconic products, consisting of "design problem space-explicit knowledge space-tacit knowledge space-innovative solution space." Furthermore, based on FBS design theory, it develops a disruptive technology innovation forecasting framework of "technology problem space-knowledge base prediction-application scenario prediction-coupled technology prediction," which collectively advances the innovation systems engineering of iconic products. In light of the analysis of the global future industrial competitive landscape, it proposes a strategy for enhancing embodied intelligence in iconic products.