Search Results (15)

Timber–steel hybridisation offers a balanced approach by capitalising on the high strength-to-weight ratio and sustainability of the timber while also benefiting from the high stiffness and ductility of the steel, contributing to the improved performance of hybrid structural elements. This paper reviews key aspects of timber–steel hybridisation, with a particular emphasis on the connection methods between timber and steel, including adhesive bonding and mechanical fastening, as well as the different types of reinforcement configurations. In particular, this review covers two main types of adhesives used in timber–steel hybrid systems, namely, epoxy and polyurethane, and two primary types of mechanical fasteners, namely, bolts and screws. The mechanical performances of all hybridisation methods are reviewed. The importance of surface treatments, such as shot blasting for steel and mechanical abrasion for timber, is also discussed as a key factor in optimising adhesive bonds. Furthermore, various reinforcement configurations, including top, bottom, side, and embedded arrangements, are evaluated for their impact on the structural efficiency and fire performance. To support this evaluation, calculations have been carried out to illustrate how different reinforcement configurations influence the stress distribution in timber–steel hybrid beams. By providing detailed insights into these critical aspects, this paper serves as a valuable decision-making tool, offering guidance for researchers and industry professionals for selecting the appropriate bonding techniques and configurations to meet specific structural objectives and advance sustainable construction practices. Full article

In the manufacturing process of precision micro parts, burrs generated in cutting and grinding processes cause various problems. Shot blasting was used in the deburring technology of cutting and grinding burr in the process of manufacturing hypodermic needles for the human body. However, we found that a secondary burr facing the inside occurs on the chin part of the needle during the blasting process. The existence of burrs on a hypodermic needle also causes several problems. We developed a new deburring method by using a vibration magnetic abrasive machining process. Our experimental results validated the effectiveness of the magnetic deburring method. Full article

This study evaluates the effects of three mechanical pre-treatment methods on S235JRG2 steel sheets: blasting with a synthetic corundum (F40), blasting with steel shot (S170), and grinding with synthetic corundum (P40). Untreated samples served as a reference. The analysis of mechanical pre-treatments focused on surface integrity, including measurements of surface roughness parameters Ra and Rz (ISO 21920-2) and subsurface microhardness (ISO 6507-1). Zinc coatings were assessed through mechanical testing (cupping test, ISO 1520) and corrosion testing in a neutral salt spray environment (ISO 9227), with results evaluated using digital image analysis. Experimental findings indicate that electroplated zinc deposition rates are influenced by surface roughness, while subsurface microhardness has no significant effect. In contrast, for hot-dip galvanizing, both parameters impact the process. The mechanical properties of electroplated zinc coatings are further affected by steel surface integrity, whereas hot-dip zinc coatings are primarily governed by intermetallic phase formation, making the influence of steel surface integrity statistically negligible. Corrosion testing revealed that blasting with a synthetic corundum is particularly unsuitable, as it leads to numerous inhomogeneities in both coating types, accelerating corrosion degradation. Full article

The vibration caused by blasting load may result in damage to high-rise buildings. In view of this consideration, an investigation of the vibration law was conducted in the context of an actual engineering project. The objective of this study was to analyze the peak particle velocity (PPV), vibration frequency, and peak particle stress (PPS) of the buildings within a range of 50 m to 250 m from the epicenter, under the condition of a single-shot charge of 30 kg. To achieve this, a combination of theoretical analysis, field tests, and numerical experiments was employed. Sadovsky’s formula was used in combination with the least squares method to fit the propagation law of ground PPV. ANSYS 17.0/LS-DYNA and Origin 8.0 software were applied to study the amplification effect of building PPV and the relationship between PPV and PPS. Taking into account the difference between the height of the ground measuring point and the height of the explosive center, we investigated the PPV of high-rise buildings under three conditions of 36 m, 6 m, and −24 m drop from the explosive center, to strengthen the in-depth understanding of resonance effect. The following conclusions were reached: the ground PPV decreases with increasing horizontal distance from the explosive center, with the radial PPV being the largest. The vertical PPV of buildings exhibits a height amplification effect, with a magnification factor of 2.66. The radial and tangential PPVs of buildings demonstrate that the middle layer exhibits a relatively modest speed, whereas the low and high layers demonstrate considerably higher speeds. The greater the vertical distance from the explosion center is, the greater is the PPV. The vibration frequency is irregular, with an average of 10 Hz. The PPV of buildings is not proportional to the PPS, which is the highest at the bottom. It is recommended that the PPS of buildings be included in the criteria for safety allowances in blasting vibration. Full article

To improve the seismic performance of a staggered truss steel framing system, the basic force unit in the truss system is replaced by a friction energy dissipation truss. The difference between a friction energy dissipation truss and an ordinary truss is that the upper chord is a friction energy dissipation composite chord. In this paper, we investigate the effects of the number of bolts and the friction surface on the energy dissipation capacity of the chord by a quasi-static test on six composite chord specimens at a scale of 1:2. The results show that the hysteresis curves of friction energy dissipation composite chords are ideal rectangles, and the energy dissipation capacity is excellent. The more bolts there are in the specimen, the slower the energy dissipation capacity of the chord decreases. Among the different friction surface specimens, the energy dissipation capacity of the aluminum friction plate specimen decays the fastest, while the energy dissipation capacity of the shot-blasted treated specimen decays substantially after the first cycle. Friction plates can improve the stability of the hysteresis properties. Based on the test results, this paper proposes a calculation method for the ultimate bearing capacity of the composite chord, which provides a basis for the design of a friction energy dissipation truss. In addition, we studied the effects of different bolt clamping forces and slotted bolt hole lengths on the energy dissipation capacity of composite chords by establishing a finite element analysis. It was shown that as the clamping force of the bolt increases, the energy dissipation capacity of the specimen becomes stronger but the stability decreases. The energy dissipation capacity of the chord is close to a linear relationship with the slotted bolt hole lengths; thus, increasing the slotted bolt hole lengths within the allowable range of inter-story drifts can enhance the energy dissipation capacity of the chord. Finally, we propose the design method of the angle steel by analyzing the force of the chord. Full article

The lack of large balanced datasets in the agricultural field is a glaring problem for researchers and developers to design and train optimal deep learning models. This paper shows that using synthetic data augmentation outperforms the standard methods on object detection models and can be crucially important when datasets are few or imbalanced. The purpose of this study was to synthesize rice leaf disease data using a Style-Generative Adversarial Network Adaptive Discriminator Augmentation (SG2-ADA) and the variance of the Laplacian filter to improve the performance of Faster-Region-Based Convolutional Neural Network (faster-RCNN) and Single Shot Detector (SSD) in detecting the major diseases affecting rice. We collected a few unbalanced raw samples of rice leaf diseases images grouped into four diseases namely; bacterial blight (BB), tungro (TG), brown-spot (BS), and rice-blast (RB) with 1584, 1308, 1440, and 1600 images, respectively. We then train StyleGAN2-ADA for 250 epochs whilst using the variance of the Laplacian filter to discard blurry and poorly generated images. The synthesized images were used for augmenting faster-RCNN and SSD models in detecting rice leaf diseases. The StyleGAN2-ADA model achieved a Fréchet Inception Distance (FID) score of 26.67, Kernel Inception Distance (KID) score of 0.08, Precision of 0.49, and Recall of 0.14. In addition, we attained a mean average precision (mAP) of 0.93 and 0.91 for faster-RCNN and SSD, respectively. The learning curves of loss over 250 epochs are 0.03 and 0.04 for Faster-RCNN and SSD, respectively. In comparison to the standard data augmentation, we achieved a t-test p-value of $9.1\times {10}^{-4}$ and $8.3\times {10}^{-5}$. Hence, the proposed data augmentation pipeline to improve faster-RCNN and SSD models in detecting rice leaf diseases is significant. Our data augmentation approach is helpful to researchers and developers that are faced with the problem of fewer imbalanced datasets and can also be adopted by other fields faced with the same problems. Full article

Surface changes and microbiological effects following shot blast polishing with viscoelastic media of the mucosal surface of resin denture bases were examined. Average surface roughness (Ra) and the depth of surface removal of specimens were measured over time, and the clinical number of microbial adhesions on the mucosal surface of dentures was clinically assessed. The results obtained showed no changes in Ra after 20 s of polishing, Ra of <0.2 µm, and a depth of surface removal < 20 µm. This method of finishing did not affect the fit of the mucosal surface of the dentures. Furthermore, the adhesion of microorganisms to the mucosal surface of dentures was significantly suppressed. Shot blast polishing with viscoelastic media is useful for finishing the mucosal surface of resin denture bases. Full article

The need to confront the problem of corrosion resistance of steel reinforcement is an issue of major importance and a perpetual challenge to the structural integrity and reliability in reinforced concrete (RC) structures. The current experimental study presents the results of the combined effect of shot blasting and coating on steel reinforcing bars in respect to their anticorrosive resistance and their mechanical behavior, at various times of exposure to corrosive environment. In the present manuscript, a comparison of different abrasive materials was primarily conducted, via electrochemical measurements (Tafel tests), to estimate the corrosion current (i_corr) for each abrasive material. After the indication that corrosion resistance can be modified by shot blasting with corundum, the method of Zn85Al15 coating was chosen to further investigate the combined effect of shot blasting with coating, in terms of percentage mass loss and mechanical behavior of steel reinforcement. The results demonstrated that, upon the completion of the surface treatment process with corundum, the mechanical performance of steel bars was improved in terms of ductility. Moreover, the Zn85Al15 coating provided a satisfactory anticorrosive protection to steel bars in the entire exposure period of accelerated corrosion. The combined contribution of shot blasting and coating processes was deemed to be very encouraging and may trigger further investigation and research, for the production of a better corrosion resistance of B500c steel. Full article

This paper attempts to compare regular shot peening (RSP) and semi-random shot peening (SRSP). A characteristic of the first method is that the peening elements hit the treated surface in sequence, with a regular distance maintained between the dimples. The other method (SRSP) is a controlled modification of the shot-peening process, which is random by nature. The shot-peening method used in this study differs from conventional shot peening (shot blasting and vibratory shot peening) in that it allows controlled and repeatable determination of the configuration and distribution of impacts exerted by the peening element on the workpiece surface, which makes the process more repeatable and easier to model. Specimens of EN-AW 7075 aluminum alloy were used for testing. The following variables were used in the experiments: ball diameter, impact energy, and distance between the dimples. Microhardness distribution in the surface layer, 2D surface roughness, and surface topography were analyzed. FEM simulations of the residual stress distribution in the surface layer were performed. It has been found that regular shot peening results in reduced surface roughness, while semi-random shot peening leads to higher surface layer hardening. Full article

Previous studies have shown that the most reliable way to evaluate the success of an implant is by bone-to-implant contact (BIC). Recent techniques allow modifications to the implant surface that improve mechanical and biological characteristics, and also upgrade osseointegration. Objective: The aim was to evaluate the osseointegration in rabbit tibia of two different titanium dental implant surfaces: shot-blasted with Al₂O₃ (SB) and the same treatment with an acid-etching by immersion for 15 s in HCl/H₂SO₄ (SB + AE). Material and methods: Roughness parameters (R_a, R_t, and R_z) were determined by white light interferometer microscopy. Surface wettability was evaluated with a contact angle video-based system using water, di-iodomethane, and formamide. Surface free energy was determined by means of Owens and Wendt equations. Scanning electron microscopy equipped with X-ray microanalysis was used to study the morphology and determine the chemical composition of the surfaces. Twenty-four grade 4 titanium dental implants (Essential Klockner^®) were implanted in the rabbit’s tibia, 12 for each surface treatment, using six rabbits. Six weeks later the rabbits were sacrificed and the implants were sent for histologic analysis. Resonance frequency analysis (RFA) was recorded both at the time of surgery and the end of the research with each device (Osstell Mentor and Osstell ISQ). Results: The roughness measurements between the two treatments did not show statistically significant differences. However, the effect of the acid etching made the surface slightly more hydrophilic (decreasing contact angle from 74.7 for SB to 64.3 for SB + AE) and it presented a higher surface energy. The bone-to-implant contact ratio (BIC %) showed a similar tendency, with 55.18 ± 15.67 and 59.9 ± 13.15 for SB and SB + AE implants, respectively. After 6 weeks of healing, the SB + AE showed an implant stability quotient (ISQ) value of 76 ± 4.47 and the shot-blasted one an ISQ value of 75.83 ± 8.44 (no statistically significant difference). Implants with different surface properties had distinctive forms of behavior regarding osseointegration. Furthermore, the Osstell system was an invasive and reliable method to measure implant stability. Conclusion: Both surfaces of implants studied showed high osseointegration. The SB and SB + AE implants used in our study had similar behavior both in terms of BIC values and RFA. The RFA systems in Osstell Mentor and Osstell ISQ confirmed nearly perfect reproducibility and repeatability. Full article

Current routine real-time PCR methods used for the point-of-care diagnosis of infectious meningitis do not allow for one-shot genotyping of the pathogen, as in the case of deadly Haemophilus influenzae meningitis. Real-time PCR diagnosed H. influenzae meningitis in a 22-year-old male patient, during his hospitalisation following a more than six-metre fall. Using an Oxford Nanopore Technologies real-time sequencing run in parallel to real-time PCR, we detected the H. influenzae genome directly from the cerebrospinal fluid sample in six hours. Furthermore, BLAST analysis of the sequence encoding for a partial DUF417 domain-containing protein diagnosed a non-b serotype, non-typeable H.influenzae belonging to lineage H. influenzae 22.1-21. The Oxford Nanopore metagenomic next-generation sequencing approach could be considered for the point-of-care diagnosis of infectious meningitis, by direct identification of pathogenic genomes and their genotypes/serotypes. Full article

Wall-stabilized arcs dominated by nozzle–ablation are key elements of self-blast circuit breakers. In the present study, high-current arcs were investigated using a model circuit breaker (MCB) in CO${}_2$ as a gas alternative to SF6 (gas sulfur hexafluoride) and in addition a long polytetrafluoroethylene nozzle under ambient conditions for stronger ablation. The assets of different methods for optical investigation were demonstrated, e.g., high-speed imaging with channel filters and optical emission spectroscopy. Particularly the phase near current zero (CZ) crossing was studied in two steps. In the first step using high-speed cameras, radial temperature profiles have been determined until 0.4 ms before CZ in the nozzle. Broad temperature profiles with a maximum of 9400 K have been obtained from analysis of fluorine lines. In the second step, the spectroscopic sensitivity was increased using an intensified CCD camera, allowing single-shot measurements until few microseconds before CZ in the MCB. Ionic carbon and atomic oxygen emission were analyzed using absolute intensities and normal maximum. The arc was constricted and the maximum temperature decreased from >18,000 K at 0.3 ms to about 11,000 K at 0.010 ms before CZ. The arc plasma needs about 0.5–1.0 ms after both the ignition phase and the current zero crossing to be completely dominated by the ablated wall material. Full article

The in-service life of ASTM A36 welded steel pipes in power plants is often shortened by ash corrosion. During the heating condition, the ash deposition on the welded steel pipes gradually reduces the thickness of the pipes, thus, reducing the lifetime. Instead of replacing the pipes with new ones, the cost could be significantly reduced if the lifetime could be further extended. Weld cladding was the method selected in this study to temporarily extend the service life of welded pipes. This paper performed the mechanical investigations of A36—A36 welded steel plates after coating the surfaces with 309L stainless steel with a cladding method. The residual stress was also tested to observe the internal stresses developed during the welding processes of A36—A36 specimens. The comparison between the coated and non-coated surfaces of welded steels was performed by using the tensile tests (at room and elevated temperatures), corrosion (pitting corrosion, intergranular corrosion, and weight-loss corrosion) tests, and wear (shot blasting) tests. The life-extension of both coatings was evaluated based on the tensile tests and the corrosion and wear tests provided the qualitative evaluations of the coating performance. The results showed that surfaces coated by cladding could be used to temporarily extend the life of ASTM A36 welded steel under the studied conditions. Full article

The global production of die forgings is an important branch of the motor industry for obvious reasons, resulting from the very good mechanical properties of the forged products. The expectations of the recipients, beside the implementation of the forging process, include also a range of supplementary procedures, such as finishing treatment including shot blasting, thermal treatment, and machining, in order to ensure the proper quality of the provided semi-product or the ready detail for the assembly line. Especially important in the aspect of the operational properties of the products is the thermal treatment of the forgings, which can be implemented in many variants, depending on the expected results. Unfortunately, a treatment of this type, realized separately after the forging process, is very time and energy-consuming; additionally, it significantly raises the production costs due to the increased energy consumption resulting from the necessity of repeated heating of the forgings for such thermal treatment. The article reviews the most frequently applied (separately, after the forging process) thermal treatments for die forgings together with the devices/lines assigned for them, as well as presents an alternative (thermoplastic) method of forging production with the use of the forging heat. The paper also presents a prototype semi-industrial controlled cooling line developed by the authors, which allows the development of the assumed heat treatment of forgings directly after forging with the use of forging heat, together with sample results of conducted tests. Full article

Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technique that uses a computer-controlled laser beam as the energy source to consolidate a metal powder according to a layer-upon-layer strategy in order to manufacture a three dimensional part. This opens the way for an unprecedented freedom in geometry, but the layer-wise build-up strategy typically results in a very poor surface finish, which is affected by the staircase effect and by the presence of partially molten particles. Surface finishing treatments are therefore necessary to obtain an adequate surface finish, to improve the fatigue behavior and to meet mechanical and aesthetic needs. The present contribution systematically compares numerous surface finishing techniques, including laser shock processing, plastic media blasting, sand blasting, ceramic shot peening and metal shot peening with steel particles of different sizes (ϕ = 0.2 mm and ϕ = 0.4 mm). The results show that all the proposed methods improve the surface quality and the fatigue life of A357.0 L-PBF parts. However, the achievement of the lowest surface roughness does not necessarily correspond to the best fatigue performance, thus suggesting that multiple mechanisms may be active and that besides surface roughness also residual stresses contribute to increase the fatigue strength. Full article