Hole In Plate Research Articles

Algorithm analysis of defect depth for PVC plate with flat-bottomed holes in active pulsed infrared thermography

Active infrared thermography (IRT) has been extensively employed in non-destructive testing in a wide variety of fields. It is capable of extracting defect information of tested object based on the infrared thermal image sequence. However, conventional infrared thermal images are often subjected to defect information with low pixel resolution, and defects are difficult to quantitatively analyze. By exploiting flat-bottomed holes in a PVC plate as defect specimens, a method for quantitative defect depth recognition based on the fusion principal component analysis (PCA) algorithm with sliding-window mechanism and the one dimensional—residual neural network—convolutional block attention module (1DResnet50_CBAM) model was proposed for the reconstructed image sequence of active IRT to address the above-described issues in this study. First, defect information and location were extracted from the original infrared sequence thermal image of the specimen using PCA algorithm with sliding-window mechanism. Then, the dimension of the defect data was reduced using the temporal characteristic of the infrared temperature field. That is, the three-dimensional defect data were transformed into 1D temporal infrared thermal signal. Moreover, the 1D infrared signal time series corresponding to the defect pixel points in the infrared sequence image served as the input to the network, and the defect depth served as the output for automatic defect detection and depth quantification. As indicated by the results, the proposed method based on the fusion PCA algorithm with sliding-window mechanism and 1DResnet50_CBAM model is capable of accurately detecting and quantifying defects. Compared with conventional prediction algorithms, the proposed model can more effectively extract defect information from the infrared detection images, with the defect depth relative prediction error less than 1.5%. Thus, the proposed model was confirmed as an effective method and model for defect recognition and quantitative analysis using infrared thermal detection technology.

Correlation between Geometrical Accuracy and Building Angle of 3D Printed Flat Plate with Circular Hole of Aluminum Alloy and Polyamide

Among variety of 3D printing or additive manufacturing methods, the laser power bed fusion (LPBF) technology for metals is now widely spread. In this study, the geometrical accuracy of 3D printed circular hole in a flat plate was investigated using aluminum alloy, Al-Si10-Mg, and polyamide, PA12. Some types of geometrical imperfections have been reported, for instance, in lattice structures or for overhang structures, but the distortion of a circular hole in a component made by LPBF has not yet been discussed in detail. This paper revealed the correlation between the geometrical parameters for distorted circular hole and the building angle. This enabled us to predict the distortion for unexperienced building angle by the interpolation, and to perform finite element analysis of mechanical behavior of a component with a circular hole. The influence of the geometrical inaccuracy on the mechanical behavior and that of the variability in mechanical properties were compared, and the former was found to be more influential. Finally, the geometry compensation in the design phase was also discussed using the statistically measured database.

Numerical Investigation of Parameters Affecting Energy Losses in Multi-Stage Perforated Plates

Abstract Perforated plates are commonly used for flow control in pressurized systems. In different industrial applications, these devices are also used in series (multistage perforated plates) to manage high-pressure drop or reduce cavitation occurrence in industrial pipelines and enhance efficiency of gas turbines in power plants. In some specific conditions, the installation of perforated plates in series is a simple and cost-effective solution that increases plant efficiency. However, the large number of design parameters complicates the search for the optimal solution. With the aim of improving the knowledge of the most relevant design parameters, in the present investigation, the dissipation characteristics of multistage perforated plates are studied. Specifically, the analysis of the dependence of the pressure loss coefficient Eu on relative spacing and hole alignment for two subsequent identical plates is performed with CFD approach. Eight plates with different characteristics such as porosity, thickness, diameter, position, and number of holes are studied. The considered porosities vary in a range of 0.3–0.5, the ratio between plate thickness and hole diameter ranges between 0.7 and 1.3, and the number of holes between 4 and 26. A critical spacing between the plates, beyond which the pressure losses are independent of the alignment of the holes, has been calculated. The results obtained are relevant for a deeper understanding of the complex phenomenon of multistage perforated plates and can be used for the design and the installation of these devices commonly used in different engineering applications.

Push-Out experiments on bearing capacity of perfobond leiste shear connectors after hydrochloric acid corrosion

The paper study the shear bearing performance and failure mechanism of perfobond leiste (PBL) shear connectors after hydrochloric acid corrosion. Seven groups of specimens with PBL shear connectors were designed, these PBL shear connectors suffered from hydrochloric acid corrosion time of 0 h, 1 h, 4 h, 12 h, 24 h, 48 h and 72 h. Herein, loading process, shear bearing capacity, load-slip curve, and failure mode were obtained by the push-out experiment, and then refined the finite element model (FEM) was established. Following the parameter analysis of 14 experiment specimens and 77 finite element models, the force mechanism of PBL shear connectors after hydrochloric acid corrosion were analyzed. With the extension of the corrosion time of PBL shear connectors, the shear capacity, deformation capacity, and slip decrease gradually. Among them, the finite element parameter analysis of PBL shear connectors demonstrates that their shear bearing capacity has the ability to be modified by raising the concrete strength, the diameter of penetrated steel bar, the diameter of steel plate holes, and changing the end bearing mode. On condition that the concrete strength is raised from C30 to C60, the shear capacity is reduced by 5.19%. When the diameter of penetrated steel bar has mushroomed from 12 mm to 25 mm, the shear capacity declines by 9.59%. Meanwhile, the shear bearing capacity of the end bearing is about 2 times of the non-end bearing. Once the diameter of steel plate holes adds 35 mm to 65 mm, the shear capacity just decreases by 2.48%. Finally, the reliability of PBL shear connectors are analyzed by the exit experiment data and the shear bearing capacity formula of PBL shear connectors. The research results can offer a reference for the shear bearing capacity of PBL shear connectors after hydrochloric acid corrosion.

A Wideband GRIN Dielectric Lens Antenna for 5G Applications.

This paper proposes a graded effective refractive indexes (GRIN) dielectric lens for 5G applications. The inhomogeneous holes in the dielectric plate are perforated to provide GRIN in the proposed lens. The constructed lens employs a collection of slabs that correspond to the specified graded effective refractive index. The thickness and the whole lens dimensions are optimized based on designing a compact lens with optimum lens antenna performance (impedance matching bandwidth, gain, 3 dB beamwidth, and sidelobe level). A wideband (WB) microstrip patch antenna is designed to be operated over the entire band of interest from 26 GHz to 30.5 GHz. For the 5G mm-wave band of operation, the behavior of the proposed lens along with a microstrip patch antenna is analyzed at 28 GHz for various performance parameters, including impedance matching bandwidth, 3 dB beamwidth, maximum gain, and sidelobe level. It has been observed that the antenna exhibits good performance over the entire band of interest in terms of gain, 3 dB beamwidth, and sidelobe level. The numerical simulation results are validated using two different simulation solvers. The proposed unique and innovative configuration is well-suited for 5G high gain antenna solutions with a low-cost and lightweight antenna structure.

Measurement of Work and Power in a Coffee-Mug Stirling Engine as a First-Year Physics Laboratory

This paper describes an experimental setup using a coffee mug, a low delta-temperature model Stirling engine, and a gas pressure sensor. The experiment is targeted toward first-year calculus-based physics labs and was designed to be implemented at low cost (approximately $120 for engine and pressure sensor) and minimal modification to off-the-shelf components for an instructor. The gas pressure sensor we used plugs directly into a USB port, and no data acquisition hub was required. Software to operate the sensor is available from the manufacturer at no additional cost. A sample student procedure handout is provided in Appendix B. Modifications for use in high school physics, algebra-based college physics, and upper-division thermodynamics courses are presented in Appendix A. Two simple modifications to the Stirling engine are required: (1) drilling a hole in the top plate of the Stirling engine and gluing a Luer lock fitting over the hole; and (2) 3D printing a spool that is then hot glued to the driveshaft of the Stirling engine. A more advanced experiment can be performed by 3D printing two gears and using a rotary motion sensor to track the phase of the system. A video demonstration of these modifications is provided. Student calculations of work done by the engine show good correlation with predicted theoretical calculations. Students also rated the experimental procedure highly for both interest and understanding.

Effect of thermal damage on dynamic and static mechanical properties of CFRP short pulse laser hole cutting

Carbon fiber reinforced polymer (CFRP) composites are widely used in the aerospace field because of their outstanding performance. Short pulse laser is an effective means for efficient and high-quality cutting of CFRP. However, the inevitable thermal effect of laser processing results in damage such as heat-affected zone, and the exposed area of fiber loses the ability to transmit force, which weakens the mechanical properties of CFRP. However, the effect of thermal damage on mechanical properties is complex. In this paper, the dynamic and static mechanical behavior of short pulse laser cutting CFRP is studied, and the effect of cutting damage on the mechanical properties is explored. The mechanical properties of CFRP plate hole laser cutting is similar to those of mechanical drilling but are lower than those of material without hole due to the existence of holes. Matrix cracking exists in the tensile fatigue of laser cutting holes, while surface cracks occur in the stress-concentrated area due to the not smooth cutting edge of mechanical drilling. Compared with small laser cutting damage, the tensile and bending strength of the CFRP plate were weakened by 11.5% and 6.2%, respectively. The tensile fatigue crack propagation and fiber protrusion are aggravated by large damage. The damage always starts at both sides of the vertical direction of the hole under 0° laying, resulting in cracks along the fiber axis until fracture. The failure mode and fracture cross-section morphology are mainly fiber tears and delamination, and the section of the 90° laying specimen surface is tidier than that of the 0° laying specimen. The mechanical properties under thermal damage studied in this paper will help to lay a foundation for damage suppression and improvement of material mechanical properties.

Failure analysis of Al2O3–C–SiO2 slide gate plates during continuous casting based on numerical simulation

The thermo-mechanical and failure behavior of the burning-free Al2O3 –C–SiO2 slide gate plate materials during the steel casting process are investigated. Firstly, the instantaneous coefficient of thermal expansion and the Young's modulus of the slide gate plate materials with different component contents at high temperature are measured. Secondly, a material constitutive model and a concrete damage plasticity mode are established based on the experiments, and adopted to simulate the failure behavior of the burning-free Al2O3–C–SiO2 slide gate plate during casting based on Finite Element Method (FEM) analysis. Results show that temperature gradient in the slide gate plate near the casting hole increased significantly and had a significant influence on cracking. The area near the casting hole of the slide gate plate is under tensile stress conditions, and then changes towards compressive stress conditions. Under those severe thermal stress conditions, crack formation is evaluated and an optimized composite structure of the slide gate plate combining advantages of reducing the risk of cracking and extending the service life is proposed. Moreover, the thermal shock test further verified that the microcrack extension was significantly alleviated due to the SiC distributed in whisker form and formed an interlocking structure in material. This work provides a reliable theoretical and experimental basis for the design and optimization of high performance Al2O3–C–SiO2 slide gate plates.

Investigation on interfacial anti-sliding behavior of high strength steel-UHPC composite beams

This paper investigates the anti-sliding behavior of high-strength steel (HSS)-to-ultra-high performance concrete (UHPC) composite beams with perfobond strip connectors (PBLs). The experimental program is comprised of two test series. The first series of push-out tests were performed on six PBLs fabricated using HSS and UHPC. For each PBL, the load-slip curve, load-uplift displacement relationship, strain history, shear stiffness, ultimate resistance, failure modes, and ductility were recorded and discussed. For the second series, three HSS-UHPC composite beams were designed and manufactured. Based on the structural responses of the composite beams under four-point flexural loadings, the interfacial sliding behavior was presented and analyzed. By employing the theory of beams-on-elastic-foundation, expressions for calculating the anti-sliding stiffness of the composite beams were deduced. Experimental results indicate that the uneven load distribution among the multiple PBLs significantly reduced the shear performance of an individual PBL. Compared to a single-hole PBL, providing double holes in the perforated plate reduced the stiffness and strength of the individual PBL by 43% and 18%, respectively, while the corresponding stiffness and strength reductions for the PBL with triple holes were 51% and 19%, respectively. The perforated plates’ end-bearing effect improved the anti-sliding stiffness of the composite beam; however, the early cracking of the UHPC slab caused by the end-bearing led to a reduced yield load of the steel beam. The anti-sliding stiffness calculated from the proposed analytical formulas correlated well with experimental results. The proposed method is anticipated to provide a reference for the anti-sliding design of HSS-UHPC composite beams in practical applications.

Three failure modes of High-Strength Steel (HSS) perfobond connector embedded in UHPC

The application of advanced high-performance materials, such as High-Strength Steel (HSS) and Ultra-High Performance Concrete (UHPC), provides innovative concepts for structural designs. To implement lighter, longer-span, and more durable structures, composite structures consisting of HSS and UHPC have been paid more attention recently since their combination might fully develop the superiority of each. Although perfobond connectors (PBLs) were reported to have excellent behavior, most studies focused on the PBLs with conventional materials and dimensions. The failure modes of PBLs with a smaller size embedded in UHPC are unclear. Besides, the current interface design methods are for ordinary composite structures, which could cause an unconservative design for HSS-UHPC composite structures. In this study, the push-out tests of HSS-UHPC PBLs with varying plate thickness and strength were performed. The fracture of perfobond plates, the fracture of perforated rebars accompanied by the yielding of hole walls, and the rebar fracture without hole wall yielding were found as the three failure modes. The failure mode significantly affected the shear strength and slip capacity, and the shear stiffness increased with the plate thickness. Then, the FE models that considered the fracture of perfobond plates and perforated rebars were established and validated. 90 numerical models with different hole diameters, plate thicknesses, and steel grades were built to investigate the transition conditions between the failure modes. Lastly, a shear capacity equation for PBLs considering the varying failure modes was proposed, which matched well with the parametric study results.

Fatigue and Progressive Damage of Thin Woven CFRP Plates Weakened by Circular Holes

BackgroundIn order to design thin-walled components it is necessary to consider the presence of holes and their effects. For high performance composite structures, this is still an issue, since usually only coupons are used in experimental observations and the influence of free edges and the hole affects the fatigue behavior mutually.ObjectiveThis work aims to find, through experimental trials, an empirical model that can be used to describe and predict the damage propagation, originating from a circular hole.MethodsA fatigue test series is performed and the damage initiation and propagation is monitored with three-dimensional digital image correlation, with which the occurring damage can be measured. Validation of the experimentally induced damage size measured with digital image correlation is performed intermediate with an in-situ measurement with active thermography and phased array ultrasonic. The novelty of this approach is that wide specimens are used, where the influence of the free edges on the hole does not occur.ResultsThe progression of the detected damage over the test reflects the applied loads, where higher loads cause larger damage. For all defined load levels a similar damage propagation is identified, allowing to establish an empirical model and fit it to the test data.ConclusionThe proposed empirical model provides a novel approach to describe and predict damage propagation originating from a circular hole in thin-walled composite plates. In addition, it is shown that the damage propagation ceases for the selected plate configuration and thus does not lead to a complete failure.

In-Vitro Antimicrobial Evaluation of Triphala Kwatha (Decoction) And its Alcoholic Extract On Wound Microbes

Triphala is the sanskrit term used in the traditional Indian system of medicine consisting of a combination of three herbal fruits namely Hareethaki (Terminalia chebula), Vibithaki (Terminalia bellerica), and Amalaki (Emblica officinalis). Triphala kwatha( Decoction) is a unique combination which has been used in Ayurveda for wound management since time immemorial. The study aimed to explore the possibilities of Triphala kwatha (decoction) and its alcoholic extract as an antimicrobial agent against wound microbes. In-vitro studies using Amox and Gentamycin as standards were done against four microorganisms i.e Staphylococcus aureus, Citrobacter, Escherichia coli, and Proteus species. These microorganisms were isolated from patient wound samples and identified by gram staining and biochemical reactions. The Agar well diffusion method or hole plate method and Agar disc diffusion method were used for In Vitro study. The in-vitro results found that Triphala kwatha(decoction) had more antimicrobial activity against microbes than the alcoholic extract of Triphala kwatha choorna. Also, it was evident that the activity of Triphala kwatha(decoction) was more against gram +ve organisms like Staphylococcus aureus.

Fluidelastic instability of a rod bundle subjected to jet cross-flow

Jet flow emanating from loss of coolant accident (LOCA) holes in the baffle plates of some pressurized water reactors (PWRs) was found responsible for flow-induced vibration in nuclear fuel bundles. This could cause fretting wear of the fuel rods at the spacer grid location. Experimental tests on prototypical rod bundles subjected to jet cross-flow showed a strong vibration response akin to fluidelastic instability of tube arrays in uniform cross-flow. Vibrations similar to flow-periodicity resonance response have also been reported.Fluidelastic instability (FEI) is the most critical flow-induced vibration mechanism. For fuel rods subject to jet-cross flow, it is important to identify the specific mechanism underlying the rod vibrations and in particular, confirm possible fluidelastic instability. In previous work, a few stability boundary correlations based on the Connors equation were developed for the baffle jetting (i.e. 2D jet) problem in PWRs. With the exception of these correlations, no theoretical model accounting for fluid–structure interaction under jet cross-flow has been reported.To investigate possible fluidelastic instability, the quasi-steady model, initially developed for tube arrays in uniform cross-flow, is extended to the problem of a rod bundle subjected to a jet cross-flow. In the extended quasi-steady model, a new formulation of the fluidelastic forces as functions of the projected rod area derivative is proposed to account for the variation of the projected area through the LOCA hole (i.e. circular jet).A significant limitation of the ‘classical’ quasi-steady model is the poor representation of the time delay effect, known to be critical for correct fluidelastic instability prediction. This shortcoming is addressed in the present work. Furthermore, unsteady flow effects are partly taken into account experimentally measuring the time delay parameter for this jet-cross-flow configuration.For the present highly compact rod array, a new test apparatus is designed and built to directly measure the time delay parameter. The new results show that the time delay to be non-constant, strongly dependent on Reynolds number while relative independent of reduced velocity for Low Re. For High Re, the time delay depends on both Re and reduced flow velocity. Based on the new measurements, a formulation for the time delay parameter, dependent on Reynolds number and reduced velocity is proposed for the highly packed fuel rod bundle.The new extended quasi-steady model conclusively confirms that the vibration phenomenon observed in experimental tests is clear fluidelastic instability induced by the jet cross-flow. Moreover, the model predicts the critical jet velocity for fluidelastic instability with an error of 9% when the new Reynolds number dependent time delay formulation is employed.

Design modification in an industrial multistage orifice to avoid cavitation using CFD simulation

BackgroundMulti-stage orifices (MSOs) are used in many industries such as oil refineries, nuclear power plants, fertilizer plants and chemical plants for pressure reduction applications. This pressure reduction often leads to an outbreak of vapors from liquid water resulting in cavitation. Cavitation imposes many problems, including loss of efficiency, erosion, and vibrations or noise. In order to mitigate the effects of cavitation on the system, it is essential to thoroughly understand the occurring phenomenon. The main objective of this study is to propose a design modification for an industrial multi-stage orifice that inhibits the onset of cavitation. MethodComputational fluid dynamics (CFD) analysis was made to simulate an actual three dimensional setup of a six-stage orifice in which cavitation occurs after the last stage of the orifice. CFD model was validated by comparing the real-time plant data with actual operating conditions. Significant FindingsVarious modifications in the geometry were tested with a focus on the orientation of the holes in orifices to eliminate the cavitation problem associated with the existing geometry. Multi-holed geometry having four holes in each orifice plate arranged at alternate positions was observed to be the best performing geometry without any cavitation effects under the same operating conditions.

Novel vibration control method of acoustic black hole plates using active–passive piezoelectric networks

In recent decades, many methods have been applied to vibration system damping and control, including acoustic black hole (ABH) structures and active–passive hybrid piezoelectric network(APPN) structures. This paper takes a two-dimensional ABH plate based on Kirchhoff plate theory as the research object, systematically researching the structure of the integration of APPN and ABH. Firstly, the vibration modes of the ABH plate are obtained by the finite element method. Then, Hamilton’s principle and the Rayleigh–Ritz method are used to derive the dynamic models. The open-loop and closed-loop control characteristics are analyzed, respectively. The results show that the ABH plates with active–passive piezoelectric networks perform better than those with active vibration control. Finally, the parameters (resistance and inductance) in APPN are optimized to obtain the best vibration control performance. The results show that the new system combined APPN and ABH firmly controls vibration and noise reduction.

Microstructure and properties of carbon fiber-H62 brass matrix composites prepared by friction stir processing

Carbon fibre (CF) reinforced H62 brass matrix composites were fabricated by friction stir process (FSP). The influence of CF compound amount and welding speed on the microstructure and properties of CF-H62 brass matrix composites was investigated by variable orthogonal experiments by drilling CF filled holes in H62 brass plates. Under the set experimental process parameters, the stirred friction processed composites with good surface formation, all without macroscopic defects, no loosening or holes. Optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure of the joints. The microstructure is a fine isometric crystal that is the result of dynamic recrystallisation. As the welding speed increased from 20 mm/min to 60 mm/min, the average grain size at the weld in the weld zone decreased from 5 μm to 2 μm. When the hole depth of the filled CF was 1.5 mm and the welding speed was 40 mm/min, the CF was most uniformly distributed in the composite area. This paper uses the orthogonal test method to optimise the formulation design of a variety of reinforcement fibre contents. The friction and wear properties as well as the physical properties of the two friction material samples were tested using a constant speed friction tester, a shear strength tester and a Rockwell hardness tester. The influence of each fibre and content on the friction material properties was investigated by extreme difference analysis; The best fibre ratio formulation was selected by combining a fuzzy comprehensive evaluation method. ANOVA was used to investigate the changes in friction material properties after the addition of graphene.

Wheat Seed Phenotype Detection Device and Its Application

To address the problem of low efficiency and automatically sense the phenotypic characteristics of wheat seeds, a wheat seed phenotype detection device was designed to predict thousand seed weight. Five commonly used varieties of wheat seeds were selected for the study, and a wheat seed phenotype detection system was built with a 2 mm sampling hole plate. Grayscale, image segmentation, area filtering and other methods were used to process the image in order to extract and analyse the correlation between thousand seed weight and seven phenotypic characteristics: wheat seed area, perimeter, long axis, short axis, ellipticity, rectangularity, and elongation. The results showed that different varieties of wheat seeds were significantly correlated with different phenotypic characteristics. Among them, the area and short axis for Luomai 26; the area, long axis, short axis, perimeter, and rectangularity for Jinqiang 11; the area and perimeter for Zhoumai 22; the area of Luomai 42; the area, short axis, and perimeter for Bainong 207 were significantly correlated with the thousand seed weight. A multiple linear regression model of thousand seed weight prediction was developed by selecting the significantly correlated phenotypic characteristic. The models showed that the R2 values of the thousand seed weight prediction models for Jinqiang 11 and Bainong 207 were 0.853 and 0.757, respectively; and the R2 values for Luomai 26, Zhoumai 22, and Luomai 42 were less than 0.5. Subsequently, PCA-MLR was used to build a thousand seed weight prediction model, and K-fold cross-validation was used for comparative analysis. Afterwards, three kinds of wheat seeds with 40–50 g thousand seed weight were selected to validate the model. The validation results showed that the more significantly correlated the phenotypic parameters were, the higher the accuracy of the thousand seed weight prediction model. The study provided a set of detection devices and methods for the rapid acquisition of the phenotypic characteristics of wheat seeds and thousand seed weight prediction.

Synthesis, characterization, anticancer activity and molecular docking of metal complexes bearing a new Schiff base ligand

2-((E)-((4-(((E)-4-Nitrobenzylidene)amino)phenyl)imino)methyl)naphthalen-1-ol, was synthesised followed by metalation with Fe(III), Co(III), Cu(II), Zn(II) and Ni(II) metals. The compounds were characterised by different methods CHN, AAS, IR, NMR, XRD, TGA and UV–Vis. The results reveal that the ligand has bidentate behavior, and it is bound with metals by a coordination bond through both the nitrogen atom of the azomethine group and the oxygen atom, this provided an octahedral geometry. The X-ray diffraction of the compounds indicate that the ligands and complexes of Co(III), Fe(III) and Zn(II) have a crystalline nature, whereas the Ni(II) and Cu(II) have an amorphous structure. The agar diffusion method (hole plate) was used to evaluate the ligand’s and its complexes’ antibacterial and antifungal effects on Salmonella enterica serovar typhi and Candida albicans, respectively. It was observed that the Fe(III) complex had the best activity among the compounds against microbial strains. Cytotoxicity of new metal complexes was also assessed against A549, HepG-2 and PC-3 cancer cells. Results demonstrated that the Cu(II) complex displayed the preeminent activity among the synthesised compounds against all the tested cell lines. Furthermore, molecular docking simulation revealed that the Fe(III) complex is shown to have a high affinity with the active sites of two targets of microbial strains. Also, the Cu(II) complex shown to has a high affinity with the active sites of three targets of A-549, HepG-2 and PC-3 cancer cells, which was confirmed by the formation of the different modes of interaction. Communicated by Ramaswamy H. Sarma

Numerical modeling of the damage mechanism of concrete-soil multilayered medium subjected to underground explosion using the GPU-accelerated SPH

The prediction of the damage mechanism of the concrete-soil multilayered medium subjected to underground explosion is a challenging task to address. In this paper, the smoothed particle hydrodynamics methodology is introduced to deal with the soil fragmentation and fracture propagation in concrete which are involved in the physical process of explosion in this double-layered medium. The Drucker–Prager constitutive model and the Holmquist–Johnson–Cook concrete constitutive model are employed to describe the dynamic behavior of the soil and concrete, respectively. Firstly, the numerical model was validated by two cases, namely the high velocity impact of an aluminium sphere on a concrete plate and the fracture propagation of rock medium under blast loading. Subsequently, the explosion in the three-dimensional concrete-soil multilayered medium involving millions of particles was simulated and investigated using GPU-accelerated smoothed particle hydrodynamics methodology. The numerical results obtained using smoothed particle hydrodynamics are compared against the available experimental data, which shows that the present SPH model can reproduce the failure pattern and fracture propagation of the concrete medium with cylindrical hole in the concrete plate and different burial depths of the explosive.

Rail transit shield tunnel deformation detection method based on cloth simulation filtering with point cloud cylindrical projection

Subway shield tunnels are important components of urban infrastructure. To maintain the safety of a tunnel during operation, tunnel deformation must be detected in a timely manner. The large quantities of metal brackets, electrical equipment, and other ancillary facilities installed along the lining of subway shield tunnels, along with bolt holes in the shield ring plate, significantly affect the detection accuracy of tunnel deformation. To increase deformation detection accuracy, a filtering method for tunnel ancillary facilities based on cloth simulation filtering with point cloud cylindrical projection is proposed. In this method, a cylindrical projection of the original point cloud of the tunnel cross-section is created. In this projection, each tunnel lining point corresponds to a projection onto the horizontal plane and the tunnel ancillaries are expanded onto the lining surface. The cloth simulation filtering algorithm is then used to separate the point clouds of the tunnel lining and ancillaries. The filtered tunnel section curves are fitted with an ellipse model based on the direct least squares method and the deformation of the tunnel is analyzed using the ellipse parameters. The repeatability values of tunnel measurements of the overall and local deformation are 0.41 and 0.66 mm, respectively. Indicating that the proposed filtering method can effectively obtain a tunnel lining point cloud from the original point cloud of the tunnel and meet the accuracy requirements of subway tunnel deformation detection.