Testing Machine Research Articles

GNBoost-Based Ensemble Machine Learning for Predicting Tribological Properties of Liquid-Crystal Lubricants.

The intricate development of liquid-crystal lubricants necessitates the timely and accurate prediction of their tribological performance in different environments and an assessment of the importance of relevant parameters. In this study, a classification model using Gaussian noise extreme gradient boosting (GNBoost) to predict tribological performance is proposed. Three additives, polysorbate-85, polysorbate-80, and graphene oxide, were selected to fabricate liquid-crystal lubricants. The coefficients of friction of these lubricants were tested in the rotational mode using a universal mechanical tester. A model was designed to predict the coefficient of friction through data augmentation of the initial data. The model parameters were optimized using particle swarm optimization techniques. This study provides an effective example for lubricant performance evaluation and formulation optimization.

Strain rate-temperature effects and constitutive models for Q690D QT steel

This paper investigates the mechanical properties of the high-strength structural steel Q690D QT (Quenched and Tempered) over a wide temperature range and a wide strain rate range. Firstly, a series of quasi-static and dynamic tests adopting the universal testing machine and Split Hopkinson Pressure Bar were carried out to investigate the mechanical properties at strain rates from 0.00025 s−1 to 5000 s−1 and temperatures from room temperature (20 °C) to 700 °C. Stress-strain curves and dynamic yield strength increase factors were extracted and investigated. Test results show that Q690D QT exhibits different strain rate effects at different temperatures, more significant at the temperatures of 600 and 700 °C, as well as the high-temperature softening effect. Dynamic strain aging effect is identified at temperatures between 300 − 600 °C for plastic strain rates of 800 s−1 and 2300 s−1, nevertheless, this effect is observed at a higher temperature range of 500–700 °C for higher plastic strain rates of 4000 s−1 and 6400 s−1. From the analysis, the adiabatic thermosoftening effect cannot be ignored when the plastic strain rates reach 4000 s−1. Finally, an improved form of the Johnson-Cook model is proposed for capturing the adiabatic temperature effects at different temperatures and validated by the test data. A parameter dynamic temperature factor is proposed to describe the comprehensive effect of strain rate, test temperature, and adiabatic thermosoftening.

Evaluating flexure properties, hardness, roughness and microleakage of high-strength injectable dental composite: an in vitro study

BackgroundRecently, a new generation of high-strength flowable dental composites has been introduced by manufacturers. The manufacturers claim that these materials have enhanced mechanical and physical properties and are suitable for use in a wide range of direct anterior and posterior restorations, even in high-stress bearing areas.AimThe objective of this study was to assess certain physical and mechanical properties of these recently introduced high-strength flowable composites in comparison to conventional multipurpose dental composites.MethodsFour types of high-strength flowable composites (Genial Universal FLO, Gaenial Universal Injectable, Beautifil Injectable, and Beautifil Flow Plus) were tested in experimental groups, while a nanohybrid conventional composite (Filtek Z350 XT) was used as the control. For flexure properties, ten rectangular samples (2 × 2 × 25 mm) were prepared from each composite material and subjected to 5000 cycles of thermocycling. Samples were then subjected to flexural strength testing using the universal testing machine. Another twenty disc-shaped specimens of dimensions (5 mm diameter × 2 mm thickness) were fabricated from each composite material for surface roughness (Ra) (n = 10) and hardness (VHN) test (n = 10). All samples underwent 5000 cycles of thermocycling before testing. Additionally, microleakage testing was conducted on 60 standardized class V cavities prepared on molar teeth and divided randomly into five groups (n = 12). Cavities were then filled with composite according to the manufacturer’s instructions and subjected to thermocycling for 1000 cycles before testing using methylene blue solution and a stereomicroscope.ResultsAll tested materials were comparable to the control group in terms of flexural strength and surface roughness (p > 0.05), with Gaenial Universal FLO exhibiting significantly higher flexural strength compared to the other flowable composite materials tested. However, all tested materials demonstrated significantly lower elastic modulus and surface hardness than the control group (p < 0.05). The control group exhibited higher microleakage scores, while the lowest scores were observed in the Gaenial Universal FLO material (p < 0.05)ConclusionThe physical and mechanical behaviors of the different high-strength flowable composites investigated in this study varied. Some of these materials may serve as suitable alternatives to conventional composites in specific applications, emphasizing the importance of dentists being familiar with material properties before making material selections.

Influence of fractal-based contact friction coefficient on the stiffness of disc springs: Experimental and numerical studies

In order to study the influence of friction coefficient on the stiffness of disc spring, A series of disc springs ( D = 71 mm) were selected in this paper. The tension and compression experiments of disc spring components were carried out by universal testing machine. The load-displacement characteristic curves of disc springs with different friction surfaces were obtained. The results show that in the loading process, the friction effect hinders the increase of the deformation of the disc spring, so that the actual stiffness of the disc spring is improved and the actual compensation amount is reduced, so this result is worthy of attention. In order to further study the influence of friction coefficient on the loading process of disc spring, according to the load-deformation formula of disc spring in A-L method, the tangential stress caused by friction is added, and the stiffness calculation model of corresponding disc spring is established by Workbench finite element software. The coefficients of different friction surfaces are used as variables for numerical calculation. The results show that the theoretical calculation, numerical calculation and experimental results of stiffness increase with the increase of friction coefficient under 0.55 h (the compensation displacement of A71 disc spring under the working displacement of corrugated tube ±10 mm). Among them, the numerical calculation results are close to the experimental results, and the error value is less than 1%. The numerical calculation results are corrected by using the experimental data, and the corrected model calculation results are in good agreement with the measured results.

Infrared temperature evolution law and thermal effect mechanism of concrete impact failure

Concrete impact failure can occur quickly and cause severe failure, which is of great significance for effective monitoring of concrete impact failure. Infrared thermal imaging technology possesses the merits of high sensitivity, noncontact, and nondestructive monitoring, rendering it extensively employed in monitoring the stability of concrete structures. However, the infrared radiation temperature (IRT) evolution law and thermal effect mechanism of concrete impact failure are not clear at present. In this study, infrared monitoring experiments were conducted on concrete impact failure and static load failure using drop hammer (DH) testing machines, pressure testing machines, and infrared thermal imagers. The infrared thermal images and the IRT change law of concrete subjected to DH impact failure were analysed. The infrared thermal effect difference and mechanism between DH impact and static load failure were compared. The results indicate that there is an infrared high-temperature point at the impact location of concrete DH impact failure, and both average infrared radiation temperature (AIRT) and maximum infrared radiation temperature (MIRT) increase suddenly. The increase in the MIRT is tens of times that of the AIRT. Compared with that of static load failure, the infrared high-temperature area of concrete DH impact failure is concentrated, while the IRT of static load failure increases overall, and the heating area is large. Moreover, the change in the IRT under DH impact failure is much greater than that under static load failure. The infrared thermal effect of concrete under DH impact failure was mainly composed of the thermoelastic effect, frictional thermal effect and tensile failure endothermic effect. The infrared data obtained for concrete impact failure should focus on the highest and lowest IRT change indicators. The highest IRT corresponds to the impact failure point, and the lowest IRT corresponds to the tensile failure position. The research results provide a new infrared thermal effect approach for monitoring the stability of concrete under impact failure.

Stretch-forming characteristics of austenitic material stainless steel 304 at hot working temperatures

Abstract The need for sheet metal forming using highly resistant materials such as titanium alloys and stainless steel has increased recently. These materials possess elevated mean flow stress values, which make them difficult to draw at room temperature. To achieve a homogeneous distribution of strain in the stretched component, reduce the load required for plastic deformation, and greatly improve material formability, hot forming is helpful. The goal of the current study is to conduct stretch-forming experiments to investigate the forming characteristics of Austenitic material Stainless Steel (ASS) 304 at Hot working temperatures. Stretch forming experiments have been conducted on the Servo electrical sheet press test machine at 650 and 800°C. The formability has been estimated by constructing a Fracture forming diagram (FFLD), limiting the height of the dome (LDH) and the distribution of the strain of stretched cups. It has been discovered that the limit of forming bounds rises with the temperature reaching 800°C, while the DSA effect causes the necking region – the area between the safe and fracture limits ‒ to decrease with additional temperature rise from 800 to 900°C. Within the experimental limitations, it has been considered that the Hot forming of ASS 304 at 650°C gives the highest strain forming limits with a uniform strain distribution in the stretched cups. From the Formability limit diagram, dome height, and strain distribution, it can be observed that ASS 304 has good limiting strain up to 800°C with lower load application.

The hemp-reinforced polypropylene composite: Effect of the alkaline and coupling agents treatment

The hemp-reinforced polypropylene composite was produced by the twin-screw extrusion in the presence of polypropylene-graft-maleic anhydride (PP-g-MA) and silane as coupling agents and subsequence by the compression molding. The hemp fiber was obtained by sodium hydroxide treatment prior to the twin-screw extruder. The PP/Hemp composite was analyzed using a universal testing machine, scanning electron microscope, differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy. The mechanical properties of the PP/MA/Hemp demonstrated a better result than that of PP/Si/Hemp in most hemp contents. The SEM images of the PP/MA/Hemp exhibited excellent interfacial bonding in PP/MA/Hemp30 without fiber pullouts. However, the fiber breakage and some fiber pullout with gaps around the fiber of PP/Si/Hemp indicate the poor bonding of the PP matrix. The functional group of the PP/Hemp composite showed the –OH cellulose result peak of the reaction between hemp fibers and polypropylene.

Anorectal lymphogranuloma venereum among men who have sex with men: a 3-year nationwide survey, France, 2020 to 2022.

BackgroundIn France, lymphogranuloma venereum (LGV) testing switched from universal to selective testing in 2016.AimTo investigate changes in LGV-affected populations, we performed a nationwide survey based on temporarily reinstated universal LGV testing from 2020 to 2022.MethodsEach year, during three consecutive months, laboratories voluntarily sent anorectal Chlamydia trachomatis-positive samples from men and women to the National Reference Centre for bacterial sexually transmitted infections. We collected patients' demographic, clinical and biological data. Genovars L of C. trachomatis were detected using real-time PCR. In LGV-positive samples, the ompA gene was sequenced.ResultsIn 2020, LGV positivity was 12.7% (146/1,147), 15.2% (138/907) in 2021 and 13.3% (151/1,137) in 2022 (p > 0.05). It occurred predominantly in men who have sex with men (MSM), with rare cases among transgender women. The proportion of HIV-negative individuals was higher than that of those living with HIV. Asymptomatic rectal LGV increased from 36.1% (44/122) in 2020 to 52.4% (66/126) in 2022 (p = 0.03). Among users of pre-exposure prophylaxis (PrEP), LGV positivity was 13.8% (49/354) in 2020, 15.6% (38/244) in 2021 and 10.9% (36/331) in 2022, and up to 50% reported no anorectal symptoms. Diversity of the LGV ompA genotypes in the Paris region increased during the survey period. An unexpectedly high number of ompA genotype L1 variant was reported in 2022.ConclusionIn rectal samples from MSM in France, LGV positivity was stable, but the proportion of asymptomatic cases increased in 2022. This underscores the need of universal LGV testing and the importance of continuous surveillance.

Effect of wood flour and compatibilizer content on the properties of wood-plastic composites

Wood-plastic composites (WPC) with are prepared by melting and mixing wood flour (WF) and thermoplastics which has green and biodegradable advantages and is of great significance in the development of the era of global resource scarcity. In this work, recycled polypropylene and WF were used as raw materials and commercially available maleic anhydride grafted polypropylene (MAH-g-PP) was used as a compatibilizer. The extrusion injection molding method was used and investigated by varying the amount of WF and compatibilizer added. The composites were analyzed for micro-morphology, melt mass flow rate, mechanical properties, and thermal stability by scanning electron microscopy (SEM), melt flow rate tester (MFR), electronic universal testing machine, and thermogravimetric analysis (TGA). According to the results, WF shows a positive effect in terms of storage and loss modulus of the composites, but it shows a negative effect in terms of thermal stability and mechanical properties. As an effective compatibilizer, MAH-g-PP plays an important role in improving the mechanical properties of the composites, especially at an additional level of 4 wt%, which maximized the overall performance of the composites.

Tensile characteristics of ultra-high-performance fibre-reinforced concrete with and without longitudinal steel rebars

Ultra-high-performance fibre-reinforced concrete (UHPFRC) specimens with and without longitudinal reinforcement were experimentally tested under direct tensile loading. The variables considered were the volume fraction of fibres (1.0% and 2.0%), the type of steel fibres (straight and hooked end) and the longitudinal steel reinforcement ratio (none and 1.2%). All of the specimens were tested using a servo-controlled fatigue testing machine in displacement control mode. The changes in displacement were monitored using linear variable displacement transducers and the digital image correlation technique. The strain profiles at different loading stages were used to identify the crack evolution process. The average localised strain was found to be 0.2–0.36%, with corresponding crack widths of 0.3–0.6 mm. A uniaxial tensile stress–strain model was developed based on the test results and data from the literature. Longitudinally steel-reinforced specimens showed both stiffening and strengthening effects. Tension-stiffened specimens with 1.0% fibres failed at a higher strain due to the formation of multiple macrocracks. In the specimens with 2.0% fibres, the rebar fractured in a brittle manner due to crack localisation. It is concluded that a higher longitudinal reinforcement ratio is needed to utilise UHPFRC effectively under tension-dominant loads.

Development of a combined harvester navigation control system based on visual simultaneous localization and mapping-inertial guidance fusion

Recently, the existing unmanned systems of combine harvesters mostly adopts satellite navigation scheme, lacking real-time observation of harvesting adjustment. To improve the operational efficiency of combine harvester assisted navigation operation, this paper designs a combine harvester navigation control system based on vision simultaneous localization and mapping (SLAM)-inertial guidance fusion. The system acquires field image information and extracts the crop boundary line as the navigation datum by binocular camera. First, the system acquires field image information through binocular camera and extracts the crop boundary line as the navigation datum. Second, fusing camera and inertial guidance information to obtain the real-time relative position of a combine harvester. Third, constrained optimization of image and inertial guidance information is achieved through a sliding window optimization method based on tightly coupled nonlinear optimization. Finally, obtain the position of the combine harvester relative to the navigation datum line, and output a signal to the steering mechanism to realize the combine harvester in the field intelligent positioning navigation control. The system consists of binocular camera, inertial measurement unit, motorized steering wheel, monitor display, angle sensor and microcontroller. During field testing, the system underwent repetitive harvesting trials over a distance of 25 m.. The testing machine performs field operations at a speed of 0.9-1.5 m/s, with an average lateral deviation range of 2.21-8.62 cm, a standard deviation range of 0.13-4.21 cm and an average cutting rate range of 92.2%-96.0%, achieving the expected harvesting effect.

Upgrade of the Universal Testing Machine for the Possibilities of Fatigue Tests in a Limited Mode

The object of the upgrade presented in this paper was an older analogue-based universal testing machine preferably designed for tensile testing. The objective of the upgrade was to create a new digitized measurement chain capable of also operating in the mode of simple fatigue tests with cyclic tensile stresses. The upgrade of the equipment mainly included the processes of calibration, creation of related calibration jigs, creation of transformation dependencies and digitization, creation or completion of missing parts of chain-signal conditioning modules, A/D converters, special jigs, etc., as elements of the experimental hardware. The degree of correctness of the calibration and of the transformation dependencies created was verified by regression analysis, and this was verified by simple correlation analysis. The correctness of the proposed modifications, was verified on the basis of the fatigue tests performed for cyclic loading. Thus, it was possible to design, develop and functionally verify a new measurement chain based on an older universal testing machine. Thus, a partially digitized pulsator was created for the possibility of fatigue testing in a technically or functionally limited mode, mainly for educational purposes as a temporary replacement for the order of magnitude more expensive commercially produced test systems.

Microstructure, microhardness, tensile and fatigue investigation on laser shock peened Ti6Al4V manufactured by high layer thickness directed energy deposition additive manufacturing

Thin layer thickness in additive manufacturing (AM) has always been a hindering factor leading to long completion times. Increasing layer thickness is accompanied by a higher tendency of surface cracks and inferior mechanical properties. These can be improved with laser shock peening (LSP). Emphasizing on the high layer thickness, this paper elucidates the high-layer thickness laser directed energy deposition (LDED) AM and the effects of LSP on the fabricated parts. Primary focus was given to the investigation of surface microcracks, microstructures, tensile and fatigue properties. Ti6Al4V bulk sample was prepared using the LDED process. Tensile, fatigue, and other samples were extracted to investigate the above-mentioned properties using different characterization tools such as optical microscope, scanning electron microscope, Vickers microhardness tester, and universal testing machine. Results showed proper depositions without major defects despite the high-layer thickness. Micro-cracks were limited to the surface only, and typical Widmanstätten patterns with parallel α lath and mixed α+β microstructures are observed. Yield strength (YS) varied from 730 MPa to 940 MPa, while ultimate tensile strength (UTS) ranged from 799.5 MPa to 953.75 MPa. Even though laser peening significantly improved micro-hardness by 49.81 % on average, not all fatigue samples observed enhanced fatigue life. A maximum improvement of 40.34 % in fatigue performance was observed in the LDED+LSPed samples. The strain hardening, plastic deformation, and grain refinement during the LSP process contributed to the enhanced mechanical properties. Some samples’ reduced fatigue life may be due to the anisotropic nature of additively manufactured parts, internal defects, and surface cracks on the specific samples. Considering high layer thickness, vertical orientation of samples, and as-prepared samples, our research shows a promising high layer thickness additive manufacturing process. The current research can be used as a base for further study on other properties and characteristics.

Thermomechanical evaluation of zinc oxide/hydroxyapatite/high‐density polyethylene hybrid composites

AbstractThis study examines the impact of zinc oxide (ZnO) on the spectral, thermal, mechanical, and morphological characteristics of developed composites of high‐density polyethylene (HDPE). Composite samples were fabricated with different compositions of ZnO (0, 5, 10, 15, and 20 wt%) along with a constant quantity of hydroxyapatite (HA, 10 wt%) in pure HDPE. The synthesized hybrid polymer composites were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), and field emission scanning electron microscopy (FESEM) methods, allowing for a thorough assessment of their spectral, thermal, mechanical, and morphological properties, repectively. FTIR analysis revealed the presence of HA and ZnO metal vibrations in the hybrid polymer samples. The thermal stability was increased by the incorporation of different amounts of ZnO, and the decomposition temperature was increased from 319.31 to 412°C for 10 wt% of ZnO hybrid composites as compared to pure HDPE. DSC findings indicated that increasing the ZnO contents, prompted the degree of crystallinity to rise to 14.81% as contrasted to neat HDPE. It was observed that yield strength and ultimate tensile strength for the 10 wt% ZnO composite increased up to 51.85% and 31.72%, respectively, compared to pure HDPE. However, at higher loading of ZnO, surface cracks were observed, which is detrimental for composite materials. Hence, the improved attributes indicated that the synthesized ZnO/HA/HDPE polymer composites can be a promising material for biomedical engineering applications.

Fracture Resistance of a Bone-Level Two-Piece Zirconia Oral Implant System—The Influence of Artificial Loading and Hydrothermal Aging

Preclinical and clinical research on two-piece zirconia implants are warranted. Therefore, we evaluated the in vitro fracture resistance of such a zirconia oral implant system. The present study comprised 32 two-piece zirconia implants and abutments attached to the implants using a titanium (n = 16) or a zirconia abutment screw (n = 16). Both groups were subdivided (n = 8): group T-0 comprised implants with a titanium abutment screw and no artificial loading; group T-HL was the titanium screw group exposed to hydro-thermomechanical loading in a chewing simulator; group Z-0 was the zirconia abutment screw group with no artificial loading; and group Z-HL comprised the zirconia screw group with hydro-thermomechanical loading. Groups T-HL and Z-HL were loaded with 98 N and aged in 85 °C hot water for 107 chewing cycles. All samples were loaded to fracture. Kruskal–Wallis tests were executed to assess the loading/bending moment group differences. The significance level was established at a probability of 0.05. During the artificial loading, there was a single occurrence of an implant fracture. The mean fracture resistances measured in a universal testing machine were 749 N for group T-0, 828 N for group Z-0, 652 N for group T-HL, and 826 N for group Z-HL. The corresponding bending moments were as follows: group T-0, 411 Ncm; group Z-0, 452 Ncm; group T-HL, 356 Ncm; and group Z-HL, 456 Ncm. There were no statistically significant differences found between the experimental groups. Therefore, the conclusion was that loading and aging did not diminish the fracture resistance of the evaluated implant system.

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology-like Load.

It is now understood that pedicle screw loosening at the implant-bone interface can lead to poor screw-bone interface purchase and decreased fixation stability. Previous biomechanical tests used cadaveric vertebrae and pull-out or torque loads to assess the effect of the insertional direction of pedicle screws on screw loosening. However, these tests faced challenges in matching biomechanical differences among specimens and simulating in vivo loads applied on pedicle screws. This study aimed to evaluate the effect of the insertional direction of pedicle screws on screw loosening using tension-compression-bending loads and synthetic bone vertebrae. Polyaxial pedicle screws were inserted into nine synthetic bone vertebrae in three directions (three samples per group): cranial, parallel, and caudad (-10°, 0°, +10° of the pedicle screw rod to the upper plane of the vertebra, respectively). Pedicle screws in the vertebrae were loaded using a polyethylene block connected to a material testing machine. Tension-compression-bending loads (100N-250N) with 30,000 cycles were applied to the pedicle screws, and displacements were recorded and then cycle-displacement curve was drawn based on cycle number. Micro-CT scans were performed on the vertebrae after removing the pedicle screws to obtain images of the screw hole, and the screw hole volume was measured using imaging analysis software. Direct comparison of displacements was conducted via cycle-displacement curve. Screw hole volume was analyzed using analysis of variance. The correlation between the displacement, screw hole volume and the direction of pedicle screw was assessed by Spearman correlation analysis. The smallest displacements were observed in the caudad group, followed by the parallel and cranial groups. The caudad group had the smallest screw hole volume (p < 0.001 and p = 0.009 compared to the cranial and parallel groups, respectively), while the volume in the parallel group was greater than that in the cranial group (p = 0.003). Correlation analysis revealed that the insertional direction of the pedicle screw was associated with the displacement (p = -0.949, p < 0.001) and screw hole volume (p = -0.944, p < 0.001). Strong correlations were found between the insertional direction of the pedicle screw and relevant parameters, including displacement and screw hole volume. Pedicle screw insertion in the caudad direction resulted in the least pedicle screw loosening.

Fracture resistance of chairside CAD-CAM lithium disilicate occlusal veneer with various designs after mechanical aging.

This study evaluated the fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate crown, onlay, and non-anatomical occlusal veneer (A-OV) with and without margin fabricated. Sixty-four CAD-CAM lithium disilicate restorations were designed as (1) complete coverage crown (CCC); (2) A-OV with margin; (3) non-A-OV with margin (NA-OV-M); and (4) non-A-OV without margin (NA-OV-NM), 16 of each. Restorations were crystallized and adhesively luted to resin dies using resin cement. Specimens were then subjected to 400,000 cycles of chewing in a mastication simulator. A universal testing machine was used to apply a compressive load at a crosshead speed of 1mm/min to the long axis of the tooth with a stainless-steel sphere until fracture occurred. One-way ANOVA followed by post hoc tests were used to assess the impact of preparation design on the fracture load of CAD-CAM lithium disilicate restorations. The highest fracture load was recorded for CAD-CAM lithium disilicate indirect restorations for non-A-OVs preparation with margin (2549±428 N) and onlay (2549±293 N) and the lowest fracture load was recorded for CCCs (2389±428 N); however, there was no significant (p = 0.640) between groups. CAD-CAM lithium disilicate restorations fabricated for anatomical and non-A-OV preparation display a fracture resistance similar to CCCs. Conservative partial coverage restorations may be considered an acceptable approach for posterior teeth.

Characterizing Edible Oils by Oblique-Incidence Reflectivity Difference Combined with Machine Learning Algorithms.

Due to the significant price differences among different types of edible oils, expensive oils like olive oil are often blended with cheaper edible oils. This practice of adulteration in edible oils, aimed at increasing profits for producers, poses a major concern for consumers. Furthermore, adulteration in edible oils can lead to various health issues impacting consumer well-being. In order to meet the requirements of fast, non-destructive, universal, accurate, and reliable quality testing for edible oil, the oblique-incidence reflectivity difference (OIRD) method combined with machine learning algorithms was introduced to detect a variety of edible oils. The prediction accuracy of Gradient Boosting, K-Nearest Neighbor, and Random Forest models all exceeded 95%. Moreover, the contribution rates of the OIRD signal, DC signal, and fundamental frequency signal to the classification results were 45.7%, 34.1%, and 20.2%, respectively. In a quality evaluation experiment on olive oil, the feature importance scores of three signals reached 63.4%, 18.9%, and 17.6%. The results suggested that the feature importance score of the OIRD signal was significantly higher than that of the DC and fundamental frequency signals. The experimental results indicate that the OIRD method can serve as a powerful tool for detecting edible oils.

Energy absorption in expanding metallic wire mesh tubes

The deformation process and energy absorption of metal wire mesh tubes under quasi-static expanding by a hemispherical-cylindrical indenter were investigated by experimental tests, finite element (FE) simulations and analytical modelling. Stainless steel and aluminum alloy tubes were tested on an MTS universal testing machine at a speed of 10 mm/min. The effects of mesh cell size and friction coefficient on the quasi-static force and specific energy absorption (SEA) were examined by FE analysis and analytical modelling. The analysis reveals that a combination of the mesh cell size and cross section dimension of the wire governs the energy absorption of tubes of equal overall dimension (diameter and length) and masses. In general, a decrease of the size of cells with constant height-to-width ratios leads to an increase of the specific energy absorption mainly due to the increased number of cells within the deformed region. An increase of the specific energy absorption is also achieved when the cell size is reduced by only decreasing the cell height. The maximum indenter force predicted by the proposed analytical model of the expanded tube deformation agrees well with the experimental results and FE simulations.

Rate-dependent damage and failure behavior of lithium-ion battery electrodes

The mechanical properties and failure behavior of composite electrodes are critical to understanding the internal short circuits and ensuring the crush safety of lithium-ion batteries used in electric transportation. This study provides a comprehensive experimental investigation into the strain rate–dependent tensile/compressive behavior and failure mechanism of both anode and cathode, covering a range from quasi-static to dynamic conditions. A universal testing machine equipped with an industrial camera was used to assess the mechanical properties and observe the deformation process of the electrodes under quasi-static conditions. Additionally, a split Hopkinson bar system, coupled with a high-speed camera, was utilized to evaluate the mechanical properties and capture the deformation process of the electrodes under dynamic loading. The detailed deformation and failure modes of the electrodes were revealed by a combination of post-mortem characterization and images from high-speed cameras. The experimental results demonstrate a significant strain rate effect on the tensile and compressive mechanical behavior and failure mechanism of both anode and cathode. The rate dependence of tensile/compressive strength and failure strain were discussed, and the underlying mechanism for strain rate sensitivity was analyzed. The results and conclusions from this study provide an important foundation for the detailed modeling and failure prediction of lithium-ion batteries under impact loading. Further, these findings facilitate the safety design of electric vehicles by informing to enhance crash safety.