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With the development of technology, the production of industrial products with 3D (3-Dimensional) printing has become widespread. Variables in production methods affect the durability of products. For this reason, studies to increase the durability of products are gaining importance. This paper aims to examine the tribological behavior of products produced in different patterns using 3D printing methods.

Friction wear tests of polylactic acid (PLA) samples produced in different patterns were carried out on a pin-on disc testing device. Friction wear tests were performed according to ASTM G-99 standard. Friction coefficient, weight loss and wear surface images were evaluated.

According to the results obtained, it was determined that pattern differences affected the tribological properties of the samples. The lowest coefficient of friction was observed in PLA1, while the highest wear resistance was found in PLA3.

Studies on the tribological properties of samples produced with a 3D printer are limited. In this study, the effect of samples with a 50% filling rate and different patterns on tribological properties was investigated. It was desired to determine the effect of different patterns on wear characteristics.

The purpose of this study is to look into the hygroscopic and tribo-mechanical properties of a polypropylene/polyamide-6 (PP/PA6) blend and a PP/PA6/Boron sesquioxide composite.

The hygroscopic behaviour of the PP/PA6 blend and PP/PA6/Boron sesquioxide composite was studied using a water contact angle goniometer in this study. To validate the hygroscopic behaviour of the blend and composite, water contact angles and surface energy of the materials were investigated. Tensile strength and hardness tests were used to determine mechanical characteristics, and tribological experiments on a pin-on-disc tribometer were used to demonstrate the friction and wear rates of dry and water-conditioned blends and composites. The melting temperature of dry and water-conditioned composites was determined using DSC analysis.

The hygroscopic effect of the PP/PA6 blend was found to be minimal in the experiment, while it was relatively dominating in the PP/PA6/Boron sesquioxide composite. Tensile strength was found to be somewhat lower in blend and composite compared to virgin PP, whereas hardness was found to be higher in both blend and composite. The composite’s tribological testing findings were fairly outstanding, with the coefficient of friction (COF) and wear rates significantly reduced due to boron sesquioxide reinforcement. The reaction between boron sesquioxide and water molecules produced boric acid, which increased the tribological characteristics of the composite even further. Following 30 days of water conditioning, the weight of the blend increased by 3.64% and the weight of the composite increased by 6.45% as compared to the dry materials. After water conditioning, tensile strength reduced by 0.8% for the blend and 14.16% for the composite. Hardness was determined to be the same in the dry state and after water-conditioning for blend but dropped 1% for composite. As compared to blend, the COF and wear resistance of composite were 15.52% and 25.16% higher, respectively. After absorbing some water, the results increased to 28.57% and 34.9%, respectively.

The mechanical and thermal behaviour of polymer composites (particularly polyamide composites) vary depending on the surrounding environment. Tests were carried out to explore the effect of water treatment on the tribo-mechanical and thermal characteristics of PP/PA6/Boron sesquioxide composite. Water treatment caused polyamides to bind with water molecules, resulting in voids in the material. The interaction between boron sesquioxide and water molecules produced boric acid, which increased the tribological characteristics of the composite.

This paper aims to design a novel test device and study the wear properties and the thermal mechanisms of roller pairs in dual-freedom sliding contacts.

On the transition process of lubrication regimes, experiments were conducted with various values of running speed and slip ratio obtained by two motorized spindles. Temperature and surviving time would be obtained of GCr15/GCr15 and DLC/GCr15 friction pairs. Micro photography was obtained with a PGI 3D stylus profiler and a confocal microscopy OLS4000-3D. An empirical mode decomposition method was used to eliminate measure errors.

Results showed that, even with little initial lubricant, rolling/sliding pairs still rotated for a certain time. With the synthetic actions of the dual-freedom sliding, the loss of lubrication and the tilt, interesting helical grooves appeared. Sliding speeds had remarkable effects on survive time, temperatures and surface topographies. In addition, the equilibrium values of the temperature and the surface roughness were obtained in sufficient oil supply. Extreme wear-out conditions were obtained with starved lubrication. Diamond-like carbon coatings showed better heat resistance and better wear resistance.

This work would be critical for the life design and the heat treatment of rolling bearings in the full flood lubrication and the starved lubrication.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0164/

This study aims to investigate the tribological performance of neat polyamide-imide (PAI) and PAI composite (PAI + 12% graphite + 3% polytetrafluoroethylene [PTFE]) under varying mediums and conditions, including dry sliding, distilled water and seawater lubrication, to determine their suitability for high-stress applications.

Tribological tests were conducted using a pin-on-disc setup with AISI 316 L stainless steel (SS) as counterface. Experiments were carried out under loads of 150 and 300 N and sliding speeds of 1.5 and 3.0 m/s. Values of temperatures, friction coefficients and wear rates were recorded to analyze the effect of fillers and lubrication mediums.

The PAI composite outperformed the neat PAI under all conditions, showing significant reductions in friction coefficients and wear rates. Seawater lubrication yielded the best results, achieving friction coefficients of 0.05 and 0.01 and specific wear rates of 18.10⁻¹⁶ m²/N and 1.10 ⁻¹⁵ m²/N, for neat PAI and PAI composite, respectively. Graphite and PTFE fillers enhanced lubrication, reduced surface temperatures and mitigated abrasive and adhesive wear mechanisms. Superior cooling and lubrication effects of the seawater contributed to these improvements.

Previous studies mainly focused on dry sliding and distilled water lubrication for the PAI and its composites, with no research on the seawater conditions. This study compares the tribological behaviors of the neat PAI and PAI composite against AISI 316 L SS under dry sliding, distilled water and seawater lubrication.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0302/

This study focuses on the impact of creep on the behavior of steel columns at elevated temperatures, considering both loading rates and creep buckling. The loading rate directly influences the duration of loading, while creep buckling illustrates how the critical buckling load depends on load duration. The capacity curve of the steel column is obtained for temperatures ranging from 400°C to 900°C, with loading rates varying from 2.5 to 0.10 mm/min. Additionally, the stress distribution across the cross-section of the column is analyzed.

A set of comprehensive experimental data at elevated temperature, including results from tension, buckling and creep buckling tests, is employed. The data from fast tension tests are used in the current study. Also, accurate coefficients for the creep model are obtained. As a result, a behavioral model for ASTM A992 steel has been developed, which accurately predicts the performance of steel columns at high temperatures. The effect of loading rate on the stress-strain curve of steel was determined and compared with Eurocode and NIST models. Additionally, parametric analysis is performed, specifically focusing on creep buckling of steel columns across a temperature range of 400°C–900°C.

In this study, a behavioral model for ASTM A992 steel has been developed, accurately predicting the performance of steel columns at high temperatures. The phenomenon of creep buckling in ASTM A992 steel columns has been investigated at temperatures ranging from 400 to 900° and compared with Eurocode standards. Reducing the loading rate in steel tensile testing can lead to a decrease of up to 40% in the tensile strength of steel at high temperatures. If a fire lasts for up to 200 min, the buckling load of the steel column can be reduced by up to 50%.

This study assesses the impact of creep on steel columns using unique experimental data obtained from steel samples. The data from fast tension tests are utilized in this study, effectively eliminating errors associated with creep effects. The behavioral model of steel is derived from these fast tension tests, and specific coefficients for the creep model are obtained. The proposed model has been validated through both fast and slow tensile tests of ASTM A992 steel. Additionally, this model has been compared with several commonly used high-temperature steel behavior models. The ability of these models to predict the buckling load of steel columns has also been evaluated.

This research examines the elements that influence consumer behavior regarding food waste reduction in buffet style restaurants. It specifically analyzes the factors that affect consumers' efforts to reduce food waste in these establishments by incorporating the theory of planned behavior (TPB), the norm activation model (NAM), and the social exchange theory (SET). Additionally, this study provides practical coping strategies for the restaurant industry.

Drawing upon an integrated framework, the study collected 547 valid responses through an online survey on Amazon’s Mechanical Turk (MTurk) for structural equation analysis. Participants who are 18 years or older and have prior experience dining in buffet style restaurants were eligible to participate in the study.

The findings underscore the profound impact of consumer awareness on their attitudes (ATT) toward minimizing food waste. Moreover, subjective norms (SN), perceived behavioral control (PBC), personal norms (PN) and establishment policies emerge as critical drivers of consumer behavior in buffet style dining settings. In light of these results, recommended strategies include enhancing consumer awareness initiatives and introducing house policies within restaurant operations.

This study employs an integrated framework that combines the NAM and TPB, taking into account the impact of house policies grounded in the SET. It provides a beneficial insight on reducing food waste in the buffet style foodservice operations from an interactive dynamic perspective between restaurants and consumers. Furthermore, this research offers valuable implications to the industry’s efforts to address food waste concerns and foster environmentally responsible behavior among consumers.

In this study, machine learning (ML) algorithms were employed to predict the shear capacity and behavior of DCSWs.

In this study, ML algorithms were employed to predict the shear capacity and behavior of DCSWs. Various ML techniques, including linear regression (LR), support vector machine (SVM), decision tree (DT), random forest (RF), extreme gradient boosting (XGBoost) and artificial neural network (ANN), were utilized. The ML models were trained using a dataset of 462 numerical and experimental samples. Numerical models were generated and analyzed using the finite element (FE) software Abaqus. These models underwent push-over analysis, subjecting them to pure shear conditions by applying a target displacement solely to the top of the shear walls without interaction from a frame. The input data encompassed eight survey variables: geometric values and material types. The characterization of input FE data was randomly generated within a logical range for each variable. The training and testing phases employed 90 and 10% of the data, respectively. The trained models predicted two output targets: the shear capacity of DCSWs and the likelihood of buckling. Accurate predictions in these areas contribute to the efficient lateral enhancement of structures. An ensemble method was employed to enhance capacity prediction accuracy, incorporating select algorithms.

The proposed model achieved a remarkable 98% R-score for estimating shear strength and a corresponding 98% accuracy in predicting buckling occurrences. Among all the algorithms tested, XGBoost demonstrated the best performance.

In this study, for the first time, ML algorithms were employed to predict the shear capacity and behavior of DCSWs.

As lubricating oils are used, their performance deteriorates and they become contaminated. The purpose of this paper is to investigate the lubrication performance of reclaimed 5 W-30 a fully synthetic used engine oil (UEO) with wear tests after refining it from a solvent-based extraction method using solvent (1-PrOH) and adsorbent materials such as cement, celite and deep eutectic solvent (DES).

The treated oil mixtures were prepared by blending engine oils with various adsorbent materials at 5% (w/w) in organic 1-PrOH solvent at a UEO: solvent ratio of 1:2 (w/w). The measurement of kinematic viscosity, density, the total acid number (TAN) and elemental analysis of oil samples was done by the ASTM standards D445/D446, D4052, D974 and D6595, respectively. Adsorbents and treated oil samples characterized by SEM-EDX, FTIR and UV analysis, respectively. Meanwhile, lubricating performance in tribological applications was evaluated through the wear test device using a rotating steel alloy 1.2379 cylinder and a stationary 1.2738 pin under 20, 40 and 80 kg load conditions. Worn surface analysis was done with SEM and 2.5D images.

It was found that when using the combination of cement and celite as an adsorbent in the reclamation of used engine oil demonstrated better lubricant properties. The properties of used engine oil were improved in the manner of kinematic viscosity of 32.55 from 68.49 mm²/s, VI (Viscosity index) value of 154 from 130, TAN of 3.18 from 4.35 (mgKOH/g) and Fe content of 11 from 32 mg/L. The anti-wear properties of used engine oil improved by at least 32% when 5% cement and 5% celite adsorbent materials were used together.

The paper is based on findings from a fully synthetic 5 W-30 A5 multi-grade engine lubrication oil collected after driving approximately 12.000 km.

The results are significant, as they suggest practical regeneration of used engine oil is achievable. Additionally, blending fresh oil with reclaimed used engine oil in a 1:1 ratio reduced wear loss by over 10% compared to fresh oil.

Reusing used engine oils can reduce their environmental impact and bring economic benefits.

This study showed that the properties of UEO can be enhanced using the solvent extraction-adsorption method. Furthermore, the study provided valuable insights into the metal concentrations in engine oil samples and their impact on lubrication performance. The order of the number of the grooves quantity and the possibility of the observed scuffing region trend relative to the samples was UEO > 5W-30 fresh oil > Treated oil sample with the adsorbent cement and celite together.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0209/

Nowadays, in building structures, dampers are connected to the building structure to reduce the damages caused by seismicity in addition to enhancing structural stability, and to connect dampers with the structure, joints are used. In this paper, three different configurations of double-lap joints were designed, developed and tested.

This paper aims to analyze three different categories of double-lap single-bolted joints that are used in connecting dampers with concrete and steel frame structures. These joints were designed and tested using computational, numerical and experimental methods. The studies were conducted to examine the reactions of the joints during loading conditions and to select the best joints for the structures that allow easy maintenance of the dampers and also withstand structural deformation when the damper is active during seismicity. Also, a computational analysis was performed on the designed joints integrated with the M25 concrete beam column junction. In this investigation, experimental study was carried out in addition to numerical and computational methods during cyclic load.

It was observed from the result that during deformation the double-base multiplate lap joint was suitable for buildings because the deformations on the joint base was negligible when compared with other joints. From the computational analysis, it was revealed that the three double joints while integrated with the beam column junction of M25 grade concrete structure, the damages induced by the double-base multiplate joint was negligible when compared with other two joints used in this study.

To prevent the collapse of the building during seismicity, dampers are used and further connecting the damper with the building structures, joints are used. In this paper, three double-lap joints in different design configuration were studied using computational, numerical and experimental techniques.

Using the Shanghai pilot free trade zone (SPFTZ) as the testing ground for further reform and opening up,the links between global value chain (GVC) and pilot free trade zone (PFTZ) programs are mutually reinforcing. GVC creates opportunities for companies to use PFTZ to reduce their costs and increase their competitiveness, while PFTZ can facilitate the movement of goods within GVC and promote the development of GVC by attracting foreign investment. Overall, in SPFTZ, the industrial structure is promoted due to trade and investment facilitation, innovation promotion, and comprehensive service platform inside SPFTZ.

This study examined industrial upgrading in GVC (IUGVC) using five indicators under three quantitative dimensions: product, process, and skill upgrading. Difference-in-Differences (DID) model is employed for the impact assessment of SPFTZ. Parallel trend analysis and Granger causality analysis are performed to check the reliability of DID outcome. Finally, robustness test using exogenous control variables are carried out.

A positive impact of SPFTZ is found on IUGVC, which is due to promoting effect of SPFTZ on foreign direct investment and technological innovation. Based on the study's findings, policy recommendations are given, such as providing business support to enterprises operating inside a PFTZ.

From a GVC perspective, the impact of theSPFTZ establishment on IUGVC cannot be ignored, and is so far missing in the literature.