Hasil untuk "Materials of engineering and construction. Mechanics of materials"

Rubén Rodríguez Elizalde

Stone materials are widely used in facades due to their durability and esthetic appeal, yet they are subject to various deterioration processes that compromise structural integrity. This chapter examines the most commonly used stones (granite, limestone, sandstone, and marble) and their physical and mechanical properties, including absorption, density, compressive strength, flexural resistance, and abrasion resistance. A comprehensive review of facade pathologies reveals that porosity plays a critical role in degradation, particularly under aggressive environmental conditions. Using advanced diagnostic techniques, this research evaluates the performance of stone materials in historical and contemporary buildings. Key findings indicate that sandstone and limestone exhibit higher vulnerability to pollution-related decay, while granites demonstrate superior resistance but require precise specification to avoid anisotropic failures. Additionally, the effectiveness of various cleaning and conservation treatments is assessed, highlighting the risks of over-aggressive cleaning methods. This chapter underscores the necessity of standardized selection criteria to enhance facade longevity and proposes guidelines for sustainable maintenance strategies. The findings provide essential insights for architects, conservation specialists, and engineers aiming to optimize the use and preservation of stone facades in both heritage and modern constructions.

FEI Fan, WEI Renchao, YANG Zhiwen, FENG Min, WANG Xiuyun

With the increasing urgency of hydrogen blending transportation in in-service natural gas pipelines in the development demand of hydrogen energy utilization， in-service pipeline materials will face the safety risk of running in hydrogen environment.To investigate the hydrogen embrittlement properties of in-service natural gas pipelines under hydrogen blending conditions， the slow strain rate tensile test and fatigue crack growth test of pipeline steel in hydrogen environment were carried out on X60 pipeline steel of an in-service natural gas pipeline， the effect of hydrogen on the tensile and fatigue properties of the tube was analyzed.The results indicated that under a total pressure of 6.4 MPa and a hydrogen blending ratio of 5%， the hydrogen embrittlement sensitivity of the in-service X60 pipe was relatively low， with fractures exhibiting mostly ductile fracture characteristics.The 5%hydrogen blending ratio did not affect the fracture characteristics.In the same hydrogen blending environment， however， the fatigue crack growth rate of X60 pipeline steel was influenced by the hydrogen environment and the stress intensity factor range at the crack tip.When the stress intensity factor range exceeded a certain threshold， the fatigue crack growth rate of X60 pipeline steel increased dramatically.The fatigue crack growth mode transitioned from ductile fracture dominated by plastic deformation at the crack tip to a mixed fracture of brittle and ductile fracture under the combined effects of hydrogen and cyclic loading.The hydrogen embrittlement sensitivity and fatigue performance of the X60 bend pipe material will be key evaluation indicators for hydrogen blended natural gas transportation in in-service pipelines.

Anton Tian

This comprehensive review examines recent advances across multiple domains in construction materials and structural engineering. The review synthesizes findings from research on bacterial/microbial concrete and self-healing materials, advanced structural modeling techniques, composite beams and post-tensioning, fatigue and cyclic loading behavior, connections and joints in composite structures, and biophilic design principles. By integrating insights from these diverse yet interconnected fields, the review identifies emerging trends, current challenges, and promising directions for future research and application. Cross-cutting themes of sustainability, technological integration, and interdisciplinary collaboration are highlighted as essential considerations for advancing construction innovation. The review concludes that the integration of biological processes, computational modeling, composite action optimization, life-cycle thinking, and human-centered design approaches collectively point toward a more sustainable, resilient, and efficient built environment.

Sallehan Ismail, Mahyuddin Ramli

Jian Yang, Xifeng Gao, Jie Xu et al.

Prabhu Azhagapillai, Karthikeyan Gopalsamy, Israa Othman et al.

Organic pollutants such as 4-nitrophenol (4-NP) pose serious environmental extortions due to their chemical stability for which efficient catalytic materials are indispensable in treating them. In this regard, the present work involves the synthesis of two different types of ferrites (NiFe2O4, and CuFe2O4), and a combination of NixCuxFe2O4 with various ratios that systemically work as efficient photocatalysts without any additional reducing agents is reported. The structural, and morphological properties of NiFe2O4, CuFe2O4, and NiCuFe2O4 were characterized by XRD, FT-IR, SEM, and HRTEM techniques. Then, the catalytic role of individual ferrite catalysts was evaluated towards catalytic reduction of 4-NP under visible light. The progress dye reduction was examined via UV–vis spectrophotometry. The effect of various concentrations, and reduction time were investigated. The kinetic rate constants determined for NiFe2O4, CuFe2O4, and NixCuxFe2O4 revealed that Ni and Cu in bimetallic ferrites promoted the reduction reaction under visible light. The results demonstrated that the photo-reduction efficiency of the Ni0.7Cu0.3Fe2O4 catalyst over 4-NP (conc. 10 ppm) to 4-AP was determined as 82 % under 120 miniutes with good recyclability up to six cycles. The mechanism of photocatalytic reduction of ferrites without the use of a reducing agent was studied. Such facile and productive ferrite materials could be employed as efficient photocatalysts for the reduction of toxic organic contaminants in environmental treatment.

V. Haldar, S. Pal

Micro plasma arc welding (MPAW) is frequently used for joining thin sheets of ferrous and nonferrous materials. In this study, austenitic stainless steel 316L of 0.5 mm thin sheets are joined by using MPAW. The weld metallurgy is characterized by field electron scanning microscopy (FESEM), Transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques to evaluate different phases formation and their orientation in detail. Mechanical tests like tensile test, micro hardness test is also carried out to measure the joint quality. It is found that the weld joint is constituent of two major phases, δ-ferrite and austenite (γ), and few secondary phases like chromium carbides. The ferrite percentage in the fusion zone is higher than the as received base material. The fusion zone hardness is increased due to the presence of high amount of ferrite and carbides. The tensile fracture surface contains lots of dimples and voids, which indicates good ductility of the joint. A defect free and good joint efficiency is achieved by using MPAW.

Tingting Wang, Xiaoming Li, Siqi Liu et al.

Bacterial infections and inadequate tissue regeneration capacity are prevalent issues in diabetic wounds, impeding the healing process. To solve these problems, a biomimetic hydrogel combined with bacterial cellulose (BC), recombinant human collagen type III (RHC), and ε-poly-L-Lysine (EPL) is fabricated by stepwise co-assembly technology. Owing to the RHC and EPL modifications of BC, the biomimetic hydrogel exhibited antibacterial effects and promoted fibroblast proliferation and angiogenesis, which accelerated the healing of diabetic wounds. Biomimetic hydrogels exhibit good mechanical properties and excellent water absorption, that can protect wounds and provide a moist environment. In addition, in vitro studies have shown that the hydrogels exhibit excellent antibacterial activity and biocompatibility. In vivo studies on diabetic wound healing have shown that biomimetic hydrogels can promote angiogenesis, accelerate collagen deposition, and re-epithelialize wound sites to promote wound healing. This study provides a new and promising strategy for the treatment of diabetic wounds.

Wenqian Zhang, Kangkang Zha, Yuan Xiong et al.

The diabetic wounds remain to be unsettled clinically, with chronic wounds characterized by drug-resistant bacterial infections, compromised angiogenesis and oxidative damage to the microenvironment. To ameliorate oxidative stress and applying antioxidant treatment in the wound site, we explore the function of folliculin-interacting protein 1 (FNIP1), a mitochondrial gatekeeper protein works to alter mitochondrial morphology, reduce oxidative phosphorylation and protect cells from unwarranted ROS accumulation. And our in vitro experiments showed the effects of FNIP1 in ameliorating oxidative stress and rescued impaired angiogenesis of HUVECs in high glucose environment. To realize the drug delivery and local regulation of FNIP1 in diabetic wound sites, a novel designed glucose-responsive HA-PBA-FA/EN106 hydrogel is introduced for improving diabetic wound healing. Due to the dynamic phenylboronate ester structure with a phenylboronic acid group between hyaluronic acid (HA) and phenylboronic acid (PBA), the hydrogel is able to realize a glucose-responsive release of drugs. Fulvic acid (FA) is added in the hydrogel, which not only severs as crosslinking agent but also provides antibacterial and anti-inflammatory abilities. Moreover, the release of FEM1b-FNIP1 axis inhibitor EN106 ameliorated oxidative stress and stimulated angiogenesis through FEM1b-FNIP1 axis regulation. These in vivo and in vitro results demonstrated that accelerated diabetic wounds repair with the use of the HA-PBA-FA/EN106 hydrogel, which may provide a promising strategy for chronic diabetic wound repair.

Awwad Talal, Alkayyal Hassan

In this paper, a dynamic shear strength analysis was performed in a finite elements environment to evaluate the stability of embankments under seismic loadings. In addition, a dynamic factor of safety depending on the results of the numerical analysis was defined. To study these parameters' effects on the embankment's stability, a parametric study concerning the embankment inclination and the soil type was performed. Finally, the numerical analysis results were compared with the results of the pseudo-static analysis according to the EC8. The results of this study show the significance of the numerical seismic analyses in comparison with the analytical calculations.

Cássio Aurélio Suski, César Edil da Costa, Júlio César Giubilei Milan

Abstract This article evaluates the effect of recrystallization annealing soaking time on the tribological behavior of cold upsetted low carbon steel. The 40% cold formed steel was subjected to annealing at 900 °C, for 10, 20, 30, 40, 50 and 60 minutes. The mechanical properties of hardness, tensile strength, yield strength and ductility, measured through specific deformation, as well as the precipitation of carbides through microstructural analysis were examined. In order to analyze the volume of removed material, the wear test was performed using a pin-on-disk tribometer according to ASTM G99. The results showed that the combination of lamellar perlite precipitation and pearlitic interlayer spacing reduction increases the mechanical strength of 1020 steel, reduces ductility, increases friction coefficient and increases wear observed by the volume of removed material increase.

ZHANG Yibo, ZHENG Liang, XU Wenyong et al.

Corundum-based (Al2O3) refractory materials prepared by powder metallurgy superalloy powder were heat treated at 950-1350 ℃ for 60 min in order to study the effect of temperature on the microstructure and particle shedding of corundum-based refractory materials. The phase structure of the refractory materials before and after heat treatment was analyzed by XRD. Scanning electron microscopy (SEM) with energy dispersive spectrum (EDS) was used to characterize the microstructure and phase composition of the refractory samples. In addition, the adhesion experiment was used to evaluate the particle shedding of the refractory materials after heat treatment at different temperatures, and explore the mechanism of pre-heating treatment reducing the possibility of particle shedding. Thermal shock test was used to evaluate the thermal shock resistance of refractory materials after heat treatment at different temperatures. The apparent porosity and bulk density were measured. The results show that with the increase of preheating temperature, the composition of calcium aluminate cement binder in refractories is gradually changed from CaAl2O4 (CA) to CaAl4O7 (CA2), and the fine ceramic particles in refractories are sintered together until the interconnected network structure is formed. With the increase of preheating temperature, the fine refractory particles in the refractory are gradually wet and spread on the large particles as aggregated and connected to form a network structure, and finally the large particles are coated. The particle adhesion of refractory gradually increases with the increase of heating temperature. The heat treatment has minor effect on the apparent porosity, bulk density and heat shock resistance of the refractory materials. However, with the increase of heating temperature, the local peeling degree of the refractory surface and mass loss rate in the thermal shock test are significantly improved. The particle shedding is obviously reduced whereas preheating for 60 min at 1150-1350 ℃, and the relative suitable preheating temperature is in the range of 1250-1350 ℃.

Kai Yun, Yongquan Zhu, Renyuan Wang et al.

Mudstone is highly sensitive to water. When it comes into contact with water, the softening phenomena such as the decrease of strength and the increase of deformation are prominent. It is of great significance to clarify its related mechanical properties. For the tertiary mudstone, a triaxial compression test and a Brazilian splitting test are carried out under the conditions of four kinds of water content (0, 10.1%, 12.5%, and 14.1%) and four kinds of confining pressures (0 MPa, 2 MPa, 5 Mpa, and 10 MPa). The test results show that (1) with the increase of confining pressure and water content, the mudstone changes from brittle failure to ductile failure. The higher the confining pressure, the greater the strength and elastic modulus. The higher the water content, the significantly lower the strength and elastic modulus, and the higher the strain. (2) With the increase of water content, the influence of confining pressure on strength is more prominent. High confining pressure can effectively inhibit the trend of strength attenuation. (3) When the water content is low (0–10.1%), the strength of the mudstone is mainly related to its own water content. When the water content increases to 10.1%–14.1%, both the confining pressure and the water content are important factors affecting the strength of the mudstone. Then, the applicability of five commonly used strength criteria to the strength prediction of softened mudstone is compared and analyzed. The results show that the Rocker strength criterion can more accurately and conveniently predict the strength of mudstone under different water content. Finally, based on this strength criterion, a nonlinear strength prediction model of softened mudstone considering water content and confining pressure effect is proposed and its good applicability is verified.

Daniel Prezgot, Stephen W. Tatarchuk, Anatoli Ianoul

Abstract The production of colors by plasmonic nanostructures is an attractive prospect over dyes as they allow ultra‐high resolution, non‐fading colors. Typical techniques for producing plasmonic color patterns such as by electron beam or ion beam lithography are expensive, slow and not well scalable. This work demonstrates a simple, lithography‐free technique for producing plasmonic colors using a silver nanocube (AgNC) based nanoparticle‐over‐mirror (NPoM) system with thermally‐generated colors. AgNC's are deposited over a metal (Au or Ag) film with a polystyrene (PS) dielectric spacer. Upon heating the system past the glass‐transition temperature of PS, the AgNC embed into the polymer, reducing the AgNC/metal film distance. This results in a strong gap‐plasmon that can shift over 200 nm across the visible spectrum during the process. The thermal embedment of AgNC in NPoM systems is tunable across the visible range, producing wide, distinct color palettes depending on the metal film used. This technique can potentially be applied to plasmonic color‐patterning systems to produce high‐resolution microscale or nanoscale patterns over a large area.

Sung-Hoon Kang, Yang-Hee Kwon, Juhyuk Moon

K.K.G.K.D. Kariyawasam, C. Jayasinghe

Nelson Damásio Ferreira, Ricardo Mendes Leal Neto, Marcello Filgueira et al.

Abstract Ti-6Al-4V and TiAl-based alloys are widely used for fabricating the implantable orthopedic devices and automotive components, respectively. Ti6Si2B-based alloys are attractive for use in orthopedic components because their higher hardness, superior biocompatibility and corrosion resistance in simulated body fluid than Ti and Ti-6Al-4V alloy. Limited information on Ti6Si2B stability in Co-dopped 67Ti-22Si-11B alloys are available in literature. This work presents the effect of cobalt doping and milling time on microstructure and Vickers microhardness of 65Ti-2Co-22Si-11B and 61Ti-6Co-22Si-11B (at-%) alloys produced by spark plasma sintering at 1100 oC for 12min using 20MPa. Samples were characterized by X ray diffraction, scanning electron microscopy, energy dispersive spectrometry, laser particle size analysis, and Vickers microhardness. Sintered alloys with 2 and 6at-%Co indicated the major presence of Ti6Si2B and Ti5Si3 dissolving up to 2.7 and 4.2 at-%Co, respectively, besides the minor precipitates of CoTi2 (4.4-16.7at-%Si) and CoTi (4.6-4.7at-%Si). Vickers microhardness of the sintered 65Ti-2Co-22Si-11B and 61Ti-6Co-22Si-11B alloys were in the range of 950-1050 and 1050-1150HV, respectively. Although the increase from 2 to 6at-%Co has reduced the Ti6Si2B stability, the Co-rich phases increased their hardness values up to 1150HV (11.3GPa), which are superior than those of commercial Ti alloys used for joint orthopedic components and automotive rotating parts.

Agus Subagio, Muhamad Abdul Kholil, Wahyu Ristiawan et al.

Anti-radar technology is essential to reinforce countries defense capacity. Previous studies have shown how the combination of a resistive material with a magnetic one is a good option for the development of radar absorbing materials. Multiwalled carbon nanotube (MWCNT)/ZnO material with MWCNT percentage variations of 1, 3, 5, and 7% has been proposed as a promising material in anti-radar technology. ZnO that is used in the synthesis of MWCNT/ZnO material resulting from a hydrothermal method was prepared using ZnSO _4 and Na _2 CO _3 as precursors. X-ray diffractograms show hexagonal phases for both MWCNT and ZnO, in the latter case hexagonal wurtzite. SEM analysis shows micrometer sheets for ZnO. The VNA test in the X-band frequency range (8 − 12.5 GHz) provides the reflection loss values. Based on the reflection loss value, MWCNT/ZnO material has an optimum absorption value of electromagnetic waves with a percentage of 3% MWCNT at a frequency of 11.2 GHz with an RL value of −31.4535 dB and a percentage of 7% MWCNT at a frequency of 11.2 GHz with an RL value of −25.3897 dB.

Ye Wu, Pengfei Ou, Jun Song et al.

Development of nanoparticles with multi-functionalities is of great importance. In this study, praseodymium sulfide (Pr _2 S _3 ) and molybdenum sulfide (MoS _2 ) nanoparticles were synthesized. The structural, morphological and optical properties of the as-obtained products were investigated by XRD, XPS, TEM, UV–vis-NIR spectroscopy, and photoluminescence spectroscopy. Pr _2 S _3 is found to be used in selective photodegradation of fluorescein sodium salt. MoS _2 can be utilized for selective photodegradation of rhodamine B. In the mixture of rhodamine B, fluorescein sodium salt and rhodamine 6 G, most of rhodamine B and part of fluorescein sodium salt are optically degraded by Pr _2 S _3 . In the mixture of rhodamine B, fluorescein sodium salt and rhodamine 6 G, part of fluorescein sodium salt and most of rhodamine B is degraded by MoS _2 . Moreover, they emit near-infrared fluorescence (800–1100 nm) when excited by the 785 nm light. Deep tissues imaging with high-contrast is shown, utilizing a nanoparticle-filled centrifuge tube covered with animal tissues (pig Bacon meat). Maximum imaging depth below the tissue surface of 1 cm is achieved. Our work provides a rapid yet efficient procedure to make nanoparticles for dual-application-potential in dye-photodegradation and near-infrared deep tissue imaging.

Natalia Soledad De Vincentis, Analía Roatta, Raúl Eduardo Bolmaro et al.

The local misorientation and orientation gradient development near grain boundaries (GBs) are analyzed in a deep drawing quality steel sheet (AKDQ) subjected to interrupted tensile tests in a notched sample. The microstructure is studied using electron backscatter diffraction (EBSD) with subgrain-level spatial resolution. The evolution of misorientation accumulation for particular GBs was traced in grains located in different zones inside the notch, identifying the effective area of influence of GBs inside the neighboring grains. A local study was performed, and the evolution in misorientation development near GB was investigated. The results show a low correlation between GB width and sharpness of the orientation gradient with the mesoscopic strain, but instead orientation gradients between GB zones and the interior of the grains were observed with increasing strain. The increase in severity observed in some GBs can be related to dislocation pile up development, which reduces the permeability of a boundary to dislocation transmission.