Strength Behavior Research Articles

Structure and corrosion properties of multilayer metal/nitride/oxide ceramic coatings formed on austenitic-martensitic steel by magnetron deposition

The design of protective coatings preventing the degradation and failure of austenitic steels in humid climate is a relevant issue. In this work, a conventional magnetron sputtering method was utilized in order to fabricate a four-layer Ni/Al-Si-N/Ni/Al-Si-O coating onto austenitic-martensitic steel. At the first stage of deposition, a three-layer coating was formed in an Ar+N2 atmosphere using a mosaic target (Ni or Al-Si), while the second stage included the deposition of the outer ceramic Al-Si-O layer in an Ar+O2 gas mixture. The studies of the structure, hardness, adhesion strength and electrochemical behavior (in 3.5 wt.% NaCl) of the «coating/steel» system were performed by means of X-ray Diffraction, electron microscopy, mechanical (indentation and scratch) tests and electrochemical impedance spectroscopy. The ceramic Al-Si-O layer exhibits an amorphous structure. The adjacent nickel layers have submicrocrystalline columnar grains. The ceramic Al-Si-N layer possesses a nanocrystalline columnar structure based on AlN + Si3N4 phases. Hardness behavior of the multilayer coating varies nonmonotonically due to a contribution of the soft amorphous phase in the upper surface layer and high-strength nanocrystalline phases in the underlying sublayers. It has been revealed that as-deposited multilayer coating decreases a corrosion rate of the substrate. The layered structure of the coating hinders the transport and diffusion of chloride ions to the substrate and decreases the corrosion rate of the substrate. However, a transport of chloride ions into the inner layers of the coating may occur through the microstructural defects preserved in the amorphous Al-Si-O layer. The scheme describing an initiation of corrosion damage and formation of corrosion products under critical corrosion conditions was proposed.

Experimental analysis of the compressive behaviour of perforated brick masonry using digital image correlation

The paper presents an experimental program on the characterisation of the mechanical behaviour of perforated brick masonry (PBM) under uniaxial compression. The study is aimed to provide a better understanding on the compressive strength and elastic behaviour of a kind of masonry hardly dealt with in the literature. The mechanical response of the investigated masonry shows actually two complexities, linked respectively to the perforated nature of the bricks and the asymmetric cross-section of the units. The latter feature is particularly recurrent in exposed brickwork composed of perforated bricks, whenever one of the face shells has a larger thickness than the other one. For this purpose, an experimental campaign was carried out on units and PBM subjected to uniaxial compressive loading. The mechanical response of PBM is investigated to accurately determine the masonry Young’s modulus and the compressive strength. Measurements obtained with conventional sensors are compared with those derived from the Digital Image Correlation (DIC) technique. Lastly, the experimental findings in terms of compressive strength and Young’s modulus are cross-referenced with the estimations derived from empirical criteria available in Eurocode 6 and ACI 530.1–02.

Study on the influence of contact surface characteristics on strength and fracture evolution of layered cemented backfill (LCB)

The stability of backfill plays a crucial role in the process of mine operation. In this study, author combined indoor experiments, surface fitting, numerical simulation, and theoretical derivation to investigate how the filling times (FTs), cement tailings ratio (CTR), and minimum CTR filling position (MCFP) affect the uniaxial compressive strength (UCS) and fracture evolution behavior of LCB. The findings demonstrate that an augmentation in FTs reduces the UCS of LCB. Moreover, the highest strength ratio resulting from diverse MCFP amounts to 2.25 times. When once filling, backfill sustain damage as a result of cracks penetrating, whereas LCB that are filled multiple times first encounter damage at the layered contact surface, followed by the gradual spread of cracks until penetrate the LCB. Through an interactive regression model, it is evident that FTs, CTR, and MCFP significantly affect the UCS. Additionally, the interaction between CTR and MCFP has a considerable impact on the UCS. Based on numerical simulation, an increase in FTs results in a wider large displacement area generated by the backfill, leading to greater horizontal and vertical displacement. The MCFP has a significant impact on the lateral displacement and maximum stress of the backfill. Theoretical derivation verifies that MCFP at the top or middle layer results in an increase in the UCS, which is consistent with the experimental findings and numerical simulation. This paper elaborates on the mechanical mechanism behind the interaction between CTR and MCFP. These findings can provide a foundation for assessing the durability and stability of LCB in subsequent stages.

Evaluating and Comparing the Tensile Strength and Clinical Behavior of Monofilament Polyamide and Multifilament Silk Sutures: A Systematic Review

Objective: This systematic review was carried out with the primary objective of verifying which suture (polyamide or silk) of two non-resorbable suture materials with different structures had better/greater tensile strength/resistance to tension, thereby presenting better mechanical behavior. The secondary objective was to verify which one had better performance. The null hypothesis was that both types of sutures had the same behavior. Methods: This systematic study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. The focused clinical question was: “In patients that underwent oral surgery treatment (P), is there significantly higher tensile strength/resistance for silk sutures (I) or for polyamide sutures (C) when comparing the outcomes (O)?”. The bibliographic search was conducted on ScienceDirect, B-On, and PubMed/MedLine between March and May 2023. The following MeSH terms were defined: sutures, breaking strength, tensile strength, oral surgery, and dentistry, which were articulated and combined using Boolean operators. There were restrictions, such as articles published in Portuguese, Spanish, or English between 1 January 2018 and 3 April 2023. The quality assessment involved the use of the Joanna Briggs Institute (JBI) checklist for RCTs and the QUIN tool (Quality Assessment Tool For In Vitro Studies) for in vitro assays. Results: Ten articles were included in this review (eight in vitro studies and two RCTs). For the RCTs, there were moderate and high levels of bias, whereas in the in vitro studies, three were classified as having a high risk of bias and five as moderate risk. The results proved that suture thread with a monofilament polyamide physical structure causes a less inflammatory reaction owing to less bacterial retention and capillarity, while multifilament sutures, such as silk, have superior mechanical characteristics. Regarding hydration, the evidence demonstrated that the preservation and stability of mechanical properties lacked uniformity. Otherwise, hyaluronic acid (HA) presents a promising solution with the same characteristics and antibacterial capabilities. Conclusion: It was possible to reject the null hypothesis that both types of sutures had the same behavior and result. It was proven by the results above that sutures with a monofilament polyamide physical structure cause a less inflammatory reaction owing to less bacterial retention and capillarity. In contrast, multifilament sutures (silk) have superior mechanical characteristics. Regarding hydration using chlorohexidine in surgical sites, the evidence demonstrated in the preservation and stability of mechanical properties lacks uniformity and congruence. However, HA seems to present a promising option with the same characteristics and antibacterial capabilities.

Inhomogeneity and anisotropy of Al-Zn-Mg-Cu alloy manufactured by wire arc additive manufacturing: microstructure, mechanical properties, stress corrosion cracking susceptibility

ABSTRACT In this study, Al-Zn-Mg-Cu alloy components were prepared using wire arc additive manufacturing (WAAM). Through multi-scale characterisation technology, performance testing and slow strain rate tensile (SSRT) testing, the microstructure, mechanical properties and stress corrosion cracking (SCC) susceptibility of WAAM Al-Zn-Mg-Cu components were studied, revealing the generation mechanism of inhomogeneity and anisotropy. The results show that with the increase of WAAM thermal cycles, the matrix precipitates (MPs), grain boundary precipitates (GBPs) and precipitation-free zones (PFZ) evolve in different paths and increase to varying degrees, resulting in performance decrease and increase in stress corrosion susceptibility, so the inhomogeneity is mainly attributed to differences in precipitated phases. The Inter-layer inclined to the scanning direction and the Inner-layer inclined to the building direction led to anisotropy in tensile strength and SCC behaviour, so the anisotropy is mainly attributed to the grain orientation and fracture mode.

Dielectric Properties of Materials Used for Microwave-Based NOx Gas Dosimeters.

Nitrogen oxides (NOx), primarily generated from combustion processes, pose significant health and environmental risks. To improve the coordination of measures against excessive NOx emissions, it is necessary to effectively monitor ambient NOx concentrations, which requires the development of precise and cost-efficient detection methods. This study focuses on developing a microwave- or radio frequency (RF)-based gas dosimeter for NOx detection and addresses the optimization of the dosimeter design by examining the dielectric properties of LTCC-based (Low-Temperature Co-fired Ceramics) sensor substrates and barium-based NOx storage materials. The measurements taken utilizing the Microwave Cavity Perturbation (MCP) method revealed that these materials exhibit more pronounced changes in dielectric losses when storing NOx at elevated temperatures. Consequently, operating such a dosimeter at high temperatures (above 300 °C) is recommended to maximize the sensor signal. To evaluate their high-temperature applicability, LTCC substrates were analyzed by measuring their dielectric losses at temperatures up to 600 °C. In terms of NOx storage materials, coating barium on high-surface-area alumina resolved issues related to limited NOx adsorption in pure barium carbonate powders. Additionally, the adsorption of both NO and NO2 was enabled by the application of a platinum catalyst. The change in dielectric losses, which provides the main signal for an RF-based gas dosimeter, only depends on the stored amount of NOx and not on the specific type of nitrogen oxide. Although the change in dielectric losses increases with the temperature, the maximum storage capacity of the material decreases significantly. In addition, at temperatures above 350 °C, NOx is mostly weakly bound, so it will desorb in the absence of NOx. Therefore, in the future development of a reliable RF-based NOx dosimeter, the trade-off between the sensor signal strength and adsorption behavior must be addressed.

Tensile strength and immersion corrosion behavior of nano-ZnO, rare earth Gd reinforced Mg nanocomposites developed by novel stir ultrasonication process

This paper presents the tensile and immersion corrosion properties of Mg-Zn-0.2Gd-xZnO (x = 1, 1.5, 2 and 2.5 wt.%) alloy and nanocomposites developed by stir ultrasonication coupled with squeeze casting. The immersion corrosion tests were performed under the simulated body fluid (SBF) conditions. The microscopic measurements indicate that the examined alloys/nanocomposites exhibit a significant decrease in grain size when both alloying elements Gadolinium (Gd) and Zinc Oxide (ZnO) nanoparticles are added. The examination of the phase by XRD indicates the presence of α-Mg and Mg2Zn, Mg7Zn3 secondary phases, which act as barriers against corrosion. The study confirmed that the incorporation of nanoparticles ZnO content ranging from 1 to 2.5 wt. % leads to a notable enhancement in yield strength (140 to 230 MPa). From the immersion corrosion test, the nanocomposites with the inclusion of 2 wt. % ZnO ceramic nanoparticles resulted in the highest level of corrosion resistance with a corrosion rate of 0.049 mm per year. This nanocomposite also shows better wettability with improved hydrophilicity. The developed Mg based advanced nanocomposites have the potential to be used in load bearing implant applications as it exhibited high corrosion resistance characteristics.

Joining of Cf/SiC composites using AlCoCrFeNi2.1 eutectic high‐entropy alloy filler by spark plasma sintering

AbstractAlCoCrFeNi2.1 eutectic high‐entropy alloy was introduced to join Cf/SiC composite by spark plasma sintering technique. The influence of holding times on microstructure, shear strength and fracture behavior of the joints was studied. When held for 7 min, the typical microstructure of the Cf/SiC‐AlCoCrFeNi2.1‐Cf/SiC joint was Cf/SiC composite → CrSi2 + FCC + Al8Cr5 + graphite → CrSi2 + FCC + Al8Cr5 → CrSi2 + FCC + Al8Cr5 + graphite → Cf/SiC composite. As the holding time extended, the Ni–Si and Fe–Si brittle phases in the joint gradually reduced, and the diffusion transition layer continued to thicken. The maximum joint strength was 23.9 MPa, which was obtained at 1450°C for 7 min. Analyzed by scanning electron microscopy and energy dispersive spectroscopy, the fracture modes of the joints joined at different holding times were all brittle fracture.

Strength and toughness of semicrystalline polymer fibers: Influence of molecular chain entanglement

The mechanical properties of oriented semicrystalline polymers fibers are mainly determined by the semicrystalline morphology in which lamellar crystals and disordered amorphous layers are in staggered arrangement. As a stress transmission channel, amorphous entanglement network can affect the strength and toughness of fiber together with crystalline phase. In this study, the relationship between mechanical properties and amorphous entanglement of oriented poly (l-lactic acid) fibers was clarified by studying the cyclic loading characteristics. Based on the Haward-Thakray model of semi-crystalline polymers, the energy contributions of the crystalline phase and the amorphous phase are separated. During the deformation of oriented fiber, the crystal will be broken under the action of tight entanglement network, and the entanglement network can transfer stress well without failure under the action of straight chain. Therefore, although the crystalline phase and the amorphous phase jointly bear the strength, the toughness and fracture behavior mainly affected by the entangled network of the amorphous phase.

MECHANICAL PROPERTIES OF DIFFERENT TYPES OF FIBER-REINFORCED CONCRETE: BENEFITS AND LIMITATIONS

Fibers are widely used in the concrete industry to enhance the mechanical properties of concrete, especially tensile strength and post-cracking behavior. This study evaluates the mechanical performance of steel, glass, polypropylene fibers, and hybrid fiber-reinforced concrete through a detailed literature review. It was found that fiber addition significantly enhances the tensile strength, flexural strength, and ductility of concrete, with variations attributed to the type and volume of fibers used. The impact on compressive strength was minimal. Fibers with high elastic modulus notably improved concrete strength, whereas fibers with lower modulus enhanced concrete’s ductility and toughness. Each fiber type presents unique benefits and limitations concerning mechanical properties, environmental resistance, and cost. Hybrid fiber reinforcement emerged as particularly effective, offering substantial improvements over single-fiber systems, and mitigating some of their inherent limitations. This research aims to provide comprehensive insights into the effects of fiber reinforcement on concrete's mechanical properties, highlighting the distinct benefits and drawbacks of different fiber types.

Hybridization of concrete by the inclusions of kaolin, alumina and silica fume: Performance evaluation

Concrete is the prime source, which fulfils the applications for construction in various forms. The prime roles of concrete industries are reducing material usage, enrichment of compressive strength, and flexural strength of concrete usage. This research focuses on recycling kaolin (mining waste) and silica fume, a great potential material for replacing coarse aggregate gravel stone and fine aggregate sand in conventional concrete as a hybrid. The developed concrete contained 5% nano alumina (Al2O3), 10% of kaolin waste (KW), and 5, 10, and 15% of silica fume (SF), and its behavior like compressive strength, flexural strength, water absorption, and acid attack behavior is studied. The molecular structure of crystalline is analyzed via X-ray diffraction (XRD). The 15% SF blended with 5% alumina and 10% KW cured within 28 and 90 days recorded high compressive and flexural strength (44 ± 1.76 MPa and 4.3 ± 0.17 MPa). XRD pattern proved their alumina, SF, and KW and found that the concrete blended with 5% alumina, 10% KW, and 15 wt% SF(90 days cured concrete) showed low water absorption (3.1 ± 0.12%). The effect of sulfuric acid behavior on weight reduction was 0.78% compared to CC1 (concrete cube without Al2O3, SF, and KW).

Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions

Although time-dependent deformation of geomaterials underpins slope-failure prediction models, the influence of strain rate on shearing strength and deformation behavior of loess remains unclear. The consolidated undrained (CU) and drained (CD) triaxial testing elucidated the impact of strain rate (0.005–0.3 mm/min) on strength envelopes, deformation moduli, pore pressures, and dilatancy characteristics of unsaturated and quasi-saturated loess. Under drained conditions with a controlled matric suction of 50 kPa, increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress (qf), initial deformation modulus (Ei), and cohesion (c), while friction angles remained unaffected. Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures. Higher rates diminished contractive volumetric strains and drainage volumes, indicating reduced densification and strength in the shear zone. Under undrained conditions, both unsaturated and quasi-saturated (pore pressure coefficient B = 0.75) loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min. For unsaturated loess, reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase. The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses. Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates. Compared to previous studies, the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence. The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.

Enhancement on compressive strength of Bangkok clay cement using novel high-strength polyethylene fibers

This study aims to investigate the effect of novel high-strength polyethylene fibers on the unconfined compressive strength (UCS) behavior of concrete produced with admixed Bangkok clay cement. Bangkok clay samples were prepared at a liquid limit of 88% and were added to ordinary Portland cement (OPC) at 2, 4, 6, 8 and 10% by weight; polyethylene fibers were also added at 0.5, 1.0, 1.5, 2.0 and 2.5% by volume. These samples were cured for 7, 14, and 28 days and subjected to an unconfined compressive test. From the test results, the cement content of 8% by weight was the optimum, and a polyethylene fiber content of 1% by volume is recommended. Moreover, the novel high-strength polyethylene fiber with 0.2 mm in diameter and 6 mm in length provided the maximum UCS value.

Quasistatic progressive crack propagation behavior of crystalline rocks based on SCB tests

To explore the influence of mineral grains on the mechanical strength and crack propagation behavior of rocks, this study investigates the quasi-static crack propagation characteristics in four types of granular structured rocks (three varieties of granite and one type of diabase rock) through a semi-circular bend three-point bending test. The implementation of a servo-controlled crack-opening displacement mechanism facilitated the realization of quasistatic crack propagation. The entire experimental procedure was documented on a camera. Subsequently, the quasistatic propagation and development of cracks in crystalline rocks were examined using digital image correlation, whereas the distribution of mineral grains and their relationship with the pattern of crack evolution were investigated under optical microscopy. The paths of the cracks exhibited noticeable deviation, which were further influenced by the mineral grains. Specifically, cracks tended to circumvent harder minerals while gravitating towards softer ones, highlighting the significant role of mineralogical composition in determining the fracture behavior of granite.

MECHANICAL PROPERTIES OF DIFFERENT TYPES OF FIBER-REINFORCED CONCRETE: BENEFITS AND LIMITATIONS

Fibers are widely used in the concrete industry to enhance the mechanical properties of concrete, especially tensile strength and post-cracking behavior. This study evaluates the mechanical performance of steel, glass, polypropylene fibers, and hybrid fiber-reinforced concrete through a detailed literature review. It was found that fiber addition significantly enhances the tensile strength, flexural strength, and ductility of concrete, with variations attributed to the type and volume of fibers used. The impact on compressive strength was minimal. Fibers with high elastic modulus notably improved concrete strength, whereas fibers with lower modulus enhanced concrete’s ductility and toughness. Each fiber type presents unique benefits and limitations concerning mechanical properties, environmental resistance, and cost. Hybrid fiber reinforcement emerged as particularly effective, offering substantial improvements over single-fiber systems, and mitigating some of their inherent limitations. This research aims to provide comprehensive insights into the effects of fiber reinforcement on concrete's mechanical properties, highlighting the distinct benefits and drawbacks of different fiber types.

Nanosuspension-Loaded Dissolving Microneedle Patches for Enhanced Transdermal Delivery of a Highly Lipophilic Cannabidiol.

Transdermal Drug Delivery System (TDDS) offers a promising alternative for delivering poorly soluble drugs, challenged by the stratum corneum's barrier effect, which restricts the pool of drug candidates suitable for TDDS. This study aims to establish a delivery platform specifically for highly lipophilic drugs requiring high doses (log P > 5, dose > 10 mg/kg/d), to improve their intradermal delivery and enhance solubility. Cannabidiol (CBD, log P = 5.91) served as the model drug. A CBD nanosuspension (CBD-NS) was prepared using a bottom-up method. The particle size, polydispersity index (PDI), zeta potential, and concentration of the CBD-NS were characterized. Subsequently, CBD-NS was incorporated into dissolving microneedles (DMNs) through a one-step manufacturing process. The intradermal dissolution abilities, physicochemical properties, mechanical strength, insertion depth, and release behavior of the DMNs were evaluated. Sprague-Dawley (SD) rats were utilized to assess the efficacy of the DMN patch in treating knee synovitis and to analyze its skin permeation kinetics and pharmacokinetic performance. The CBD-NS, stabilized with Tween 80, exhibited a particle size of 166.83 ± 3.33 nm, a PDI of 0.21 ± 0.07, and a concentration of 46.11 ± 0.52 mg/mL. The DMN loaded with CBD-NS demonstrated favorable intradermal dissolution and mechanical properties. It effectively increased the delivery of CBD into the skin, extended the action's duration in vivo, and enhanced bioavailability. CBD-NS DMN exhibited superior therapeutic efficacy and safety in a rat model of knee synovitis, significantly inhibiting TNF-α and IL-1β compared with the methotrexate subcutaneous injection method. NS technology effectively enhances the solubility of the poorly soluble drug CBD, while DMN facilitates penetration, extends the duration of action in vivo, and improves bioavailability. Furthermore, CBD has shown promising therapeutic outcomes in treating knee synovitis. This innovative drug delivery system is expected to offer a more efficient solution for the administration of highly lipophilic drugs akin to CBD, thereby facilitating high-dose administration.

Shear Strength Behavior of Clayey Soil Reinforced with Natural Agent-Treated Coir Fiber

Shear Strength Behavior of Clayey Soil Reinforced with Natural Agent-Treated Coir Fiber

Strength Behavior of Slurry-Like Mud Treated with Physicochemical Combination Method

Strength Behavior of Slurry-Like Mud Treated with Physicochemical Combination Method

Constitutive modeling structural behaviors of Shanghai deep clay

The rapid development of underground engineering requires a comprehensive understanding of deep soils. Existing study about the deformation and strength behaviors of Shanghai clay is mostly focused on shallow soft clay (generally within 30 m depth), while counterpart for deep clay is needed. This work investigates the physical properties and mechanical behaviors of Shanghai deep clay (block samples of layer (8) obtained at a depth of around 50 m), via conducting a series laboratory tests including physical property tests, onedimensional consolidation tests and undrained triaxial compression tests, performing constitutive modelling. The results show: (1) Shanghai layer (8) clay can be classified as a low-plasticity silty clay, and the void ratio measured in the laboratory of the block samples is larger than remoulded samples; (2) The clay is a normally consolidated clay, and the block samples show greater compressibility and stronger initial structure; (3) The block samples show contraction behaviors in the undrained triaxial compression tests; (4) The structural behaviors is well captured by structural bounding surface model.

Fatty alcohols as sustainable compatibilizer agents for the compound of natural rubber/silica: The curing, rubberiness and tensile strength behaviours

Fatty alcohols are derived from palm oil production and, stearyl and lauryl alcohols are examples of them. The stearyl and lauryl alcohols have the potential to be used as rubber additives for the compounding and vulcanizing processes. These materials are relatively new as rubber additives and, they were added into silica-filled natural rubber (NR) compound. The aim of using them is to increase the grade of silica dispersion inside the NR matrix. Initially, the NR was filled by (precipitate) silica at 30 parts per hundred of NR, whilst the fatty alcohols were added into the silica-filled NR with variable concentrations from 1 to 4 phr, separately. The compounds of NR/silica/stearyl alcohol and NR/silica/lauryl alcohol have been vulcanised at 150 °C by implementing a semi-efficient rubber composition. From the vulcanization behaviour, it was observed that both fatty alcohols have the role of compatibilizer and plasticising agents for the compound of NR/silica. Those fatty alcohols decreased the viscousness but increased the curing rate index (CRI). The more concentration of fatty alcohols was supplied, the less viscousness and the higher the CRI. Those fatty alcohols also shifted the crosslinking level and tensile strength. It also observed that the break elongation or rubberiness has been shifted up. Tensile strength has been shifted to a maximal value with a 2 phr of stearyl alcohol or 3 phr of lauryl alcohol addition.