Plate Thickness Research Articles

Moving-Load Dynamic Analysis of Thick Sandwich Plates with Titanium Alloy Face Sheets and a Porosity-Dependent FG-GPLRC Core

Moving-Load Dynamic Analysis of Thick Sandwich Plates with Titanium Alloy Face Sheets and a Porosity-Dependent FG-GPLRC Core

Study on Damage Index for Beam–Column Joints with Flush End-Plate Connections

Experimental results from 109 flush end-plate (FEP) connections were analyzed to investigate the failure modes and damage index of FEP connections across various damage states. The present study was conducted in accordance with the performance design objectives specified in China’s GB50011-2010 Code for Seismic Design of Buildings. The observed rotation angles and corresponding rotation factors were systematically categorized using a probabilistic statistical approach, with the 95% confidence lower limit as the primary constraint. The damage states of FEP connections were classified as virtually undamaged, lightly damaged, moderately damaged, severely damaged, and joint failure. A minimum plate thickness of 12 mm and a minimum high-strength bolt diameter of 20 mm are recommended to be used for the FEP connections, in accordance with building codes in China, the United States, and Europe. Quasi-static tests of six FEP connections were conducted to validate the damage-state categorization. The results revealed that for connections undergoing moderate and severe damage, the mean rotation factor deviated from the theoretical values proposed in this study by 3.7% and 9.4%, respectively. Therefore, the damage state of FEP connections can be reliably predicted based on different rotation angles using the damage-state categorization presented herein.

Hydrogen-as-a-probe applied to investigate the influence of extraction and preparation methods on TDS spectra of 13CrMo4-5 samples

AbstractThermal desorption spectroscopy (TDS) provides rich information on the desorbed hydrogen flow rate activated at different heat energy levels, supporting high-resolution assessment of small-scale features that are preferential trapping sites. TDS spectra are also highly sensitive to hydrogen uptake from the sample’s extraction and preparation methods, whose influence requires further evaluation. In this research, hydrogen-as-a-probe is applied to evaluate the influence of extraction, surface grinding, dwelling time, plate thickness, and sample thickness on TDS spectra of 13CrMo4-5 steel. Validation of TDS results confirms that all hydrogen present in the sample before the TDS measurement, including metallurgical hydrogen and hydrogen uptake from the studied methods, is desorbed during the first heating cycle. Results indicate that peaks 1 and 3 are negligibly influenced by the studied methods. Peak 2 and total hydrogen concentration are significantly influenced by sample extraction and surface grinding methods, which provide the main outcomes of this work. Methods based on severe solid-state distortion, like machine cutting and grit P320, present an increased total hydrogen content of 99% and 142%, respectively. Dwelling time and plate thickness have small influence on hydrogen content. Reducing the sample thickness results in less total hydrogen concentration at a rate of 5.7 at.ppm/mm.

Laser Hybrid Welding—An Advanced Joining Technique for Welding of Thick Plates of Maraging Steel

Laser Hybrid Welding—An Advanced Joining Technique for Welding of Thick Plates of Maraging Steel

Novel quadrilateral strain-based finite element for static, free vibration, and buckling analysis of plates

This paper focuses on the static analysis, free vibration, and buckling validation of Reissner–Mindlin plates using a newly developed quadrilateral finite element, termed FNSBP, which is based on the strain approach. The proposed element is equipped with three essential external degrees of freedom at each of its four corner nodes. The displacement field is formulated using assumed strain functions that inherently satisfy the compatibility equations. This new element was developed to improve upon the previously introduced SBRP strain-based rectangular plate element. The effectiveness and robustness of the FNSBP element are evaluated through various numerical examples involving both thick and thin plates of different geometries. Its performance is benchmarked against displacement-based elements from the literature and analytical solutions, demonstrating superior accuracy and convergence in many cases. The results indicate that the FNSBP element provides significant improvements in computational efficiency and accuracy, especially for complex plate configurations under different loading and boundary conditions, validating its applicability in structural analysis.

Effect of Process Parameters on the Mechanical Properties of Simultaneous Double-Sided Friction Stir Welding Joints

Currently, conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys, and its application to thick plates is still challenging in terms of welding efficiency and joint mechanical properties. Simultaneous double-sided friction stir welding (SDS-FSW) is a high-efficiency joining technique specifically developed for welding thick plates. However, there is little research on the influence of SDS-FSW process parameters on the joint mechanical properties. In this study, a 12 mm thick AA6061-T6 aluminum alloy and dual robot welding equipment are used to conduct SDS-FSW experiments exploring the influence of rotational speed ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} and welding speed v on the mechanical properties and microstructure. The results show that when the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 60–80 mm/min, smooth and defect-free thick plate aluminum alloy SDS-FSW joints can be obtained, and the macroscopic morphology of the joints is distributed in a “dumbbell” shape. The grain size in the weld nugget zone increases with increasing welding heat input. The microhardness distribution in the joint displays a “W” shape, and the hardness value of the weld nugget zone can reach 67% to 86% of that of the base metal (BM). The junction between the thermo-mechanically affected zone and the heat affected zone is the weakest region of the joint, with the lowest hardness being approximately 51% of that of the BM. When the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 140 mm/min, the SDS-FSW joint has the highest tensile strength, reaching 78.43% of the BM strength and exhibiting ductile fracture characteristics. This research indicates that acceptable weld strength in thick aluminum alloys can be achieved via the SDS-FSW joining mechanism, highlighting its significant potential for industrial applications.

Automatic Defects Recognition of Lap Joint of Unequal Thickness Based on X-Ray Image Processing

It is difficult to automatically recognize defects using digital image processing methods in X-ray radiographs of lap joints made from plates of unequal thickness. The continuous change in the wall thickness of the lap joint workpiece causes very different gray levels in an X-ray background image. Furthermore, due to the shape and fixturing of the workpiece, the distribution of the weld seam in the radiograph is not vertical which results in an angle between the weld seam and the vertical direction. This makes automatic defect detection and localization difficult. In this paper, a method of X-ray image correction based on invariant moments is presented to solve the problem. In addition, a novel background removal method based on image processing is introduced to reduce the difficulty of defect recognition caused by variations in grayscale. At the same time, an automatic defect detection method combining image noise suppression, image segmentation, and mathematical morphology is adopted. The results show that the proposed method can effectively recognize the gas pores in an automatic welded lap joint of unequal thickness, making it suitable for automatic detection.

Research on axial compression behavior of cold-formed steel built-up T-shaped columns

A series of axial compression tests were conducted on cold-formed steel (CFS) built-up T-shaped columns consisting of three identical single-limb sections connected by longitudinally arranged high-strength bolts and filler plates at the webs. At first, the buckling behavior, failure mode, ultimate bearing capacity, and load response curves of columns are analyzed. Subsequently, finite element models of tested columns were then developed and validated to provide a base for conducting parametric studies of built-up T-shaped columns with different slenderness ratio, web height to plate thickness ratio and bolt spacing. Finally, the design methods in the Chinese code GB50018–2002 and AISI S100–16 specifications for predicting the resistance of the built-up T-shaped columns were evaluated by using both the test and numerical results. The study shows that the current design procedure in AISI S100–16 are unstable in predicting the resistance of the built-up T-shaped columns within a certain range of overall slenderness ratio, while the provisions in the Chinese code GB50018–2002 are overly conservative. Hence, a reliable design procedure is proposed based on the the Effective Width Method (EWM) in the Chinese code GB50018–2002 equations obtained from the paper. The strength predictions of the proposed design procedure match well with those of experimental studies in the literature and the experimental and numerical studies of this paper.

Analysis of FGM-type porous sandwich plates subjected to free vibration using Student Order Theory

This research adopts a high-order shear deformation theory to explore the free vibration characteristics of square porous sandwich plates constructed from functionally graded materials (FGMs). This theory effectively addresses shear deformation effects without necessitating a shear correction factor. The material properties of the FGMs change continuously throughout the plate's thickness, following a power-law distribution (P-FGM) based on the volume fractions of the component materials. The outer layers are metal, while a uniform ceramic layer constitutes the core. The governing equations are derived from the principle of virtual displacements. This study examines three different porosity distributions. By utilizing Hamilton's principle, the equations of motion were formulated. The numerical analysis demonstrates how the distribution of materials, geometry, and porosity affect the free vibration responses of FGM sandwich plates. The validity of the present theory is studied by comparing certain results obtained with other results published in the literature.

Multi-pass laser welding with cut-wire particles of 50 mm thick steel plates

Multi-pass laser welding with filler wire feeding shows significant potential for welding thick plates. However, this method faces challenges due to the need for edge preparation and stringent control of parameters such as wire feed speed and the relative positioning to the laser beam. Utilizing cut-wire particles instead of solid wire may address these limitations. This investigated the usage of cut-wire particles in multi-pass laser welding of 50 mm thick square groove butt joints. The study involved welding experiments to optimize the amount of cut-wire particles, laser power density, and travel speed for root and buildup passes. The final pass employed hybrid laser-arc welding to compensate for the voids between the cut-wire particles. The joints were successfully welded in eight passes. Mechanical testing demonstrated that the welded joints exhibited strength surpassing that of the base metal. The heat-affected zone displayed a hardness exceeding 350 HV. The fusion zones of the hybrid and buildup passes showed an impact toughness of 100 J, while the root pass fusion zone exhibited an impact toughness of approximately 45 J. This difference was attributed to the presence of a bainitic/martensitic microstructure in the root pass, compared to a mixture of acicular and grain boundary ferrite in the hybrid and buildup passes.

Correction: Investigation of stress corrosion cracking behavior of friction stir welded thick al 6061-t6 alloy plate

Correction: Investigation of stress corrosion cracking behavior of friction stir welded thick al 6061-t6 alloy plate

Free Vibration and Buckling Analyses of Functionally Graded Plates With Graphene Platelets Reinforcement

Abstract While existing research has focused on using graphene platelets (GPLs) as reinforcement for homogeneous matrices, this study proposes a new nanocomposite for plate structures consisting of GPLs incorporated into a conventional functionally graded matrix with the aim of enhancing their overall stiffness. The performance of such plates is evaluated via free vibration and buckling analyses in the present study. Note that the matrix phase is graded continuously with the power law distribution across the plate's thickness, whereas various GPL dispersion patterns along the thickness are studied. The material properties of the typical functionally graded matrix are determined by the rule of mixture, and then those of the composite are estimated by the modified Halpin–Tsai model as well as the rule of mixture. Based on Hamilton's principle and the novel four-unknown refined plate theory (RPT4), the governing equations of the plate are developed. The Navier-type solution scheme is then adopted to get the critical buckling load and natural frequency of the nanocomposite plate. Numerical findings are examined to evaluate the novel nanocomposite plate model, and a parametric study is also conducted. In addition, high-accurate results are provided via the Navier-type solution here as benchmark solutions for further studies on functionally graded material structures reinforced by GPLs.

Microstructure and development of the dermal ossicles of Antarctopelta oliveroi (Dinosauria, Ankylosauria): A complex morphogenetic system deciphered through three-dimensional X-ray microtomography.

Ankylosaurs were a group of heavily armored non-avian dinosaurs (Dinosauria, Ankylosauria), represented by a relatively abundant fossil record from the Cretaceous of North and South America. Their dermal skeleton was characterized by large osteoderms whose development and functional role have been largely investigated. However, interstitial small ossicles, forming between these osteoderms, have been far more overlooked and it remains unknown whether they were formed through the ossification of a preexisting fibrous matrix of connective tissue (i.e., metaplasia) or by a cell-induced differentiation of new fiber bundles followed by mineralization (i.e., neoplasia sensu (Zeitschrift für Wissenschaftliche Zoologie, 1858, 9, 147)). Here, we propose a hypothesis on the developmental origin of these small ossicles in the ankylosaurian Antarctopelta oliveroi using light microcopy, scanning electron microscopy and three-dimensional virtual histology through propagation phase-contrast synchrotron radiation micro-computed tomography (PPC-SRμCT). Ossicles are located in the dermis. They are composed of two layers: (1) a thin external layer, and (2) a thick basal plate, composed of collagen fiber bundles, which forms the main part of the ossicle. The external layer is made of a smooth, vitreous mineralized tissue that does not look like bone. The basal plate, however, is of osseous origin. In this basal plate, the collagen fiber bundles are organized in two orthogonal systems: one horizontal-observable in cross-sections-and one vertical-observable in the primary plane of sections sensu (Journal of Vertebrate Paleontology, 2004, 24, 874). The horizontal system is itself composed of successive layers of collagen fiber bundles arranged into an orthogonal plywood-like structure. The bundles of the vertical system radiate from the center of the ossicle at the level of the transition between the external layer and the basal plate and run towards the periphery of the basal plate. Their thickness increases from the center of the ossicle towards its periphery. Numerous bundles of the vertical system form thin threads that interweave and penetrate within the thick bundles of the horizontal system. Our new data suggest that the ossicles were at least partially formed by metaplasia, that is, through the ossification of a preexisting fibrous matrix of connective tissue. This process was probably supplemented by a cell-induced differentiation of new fiber bundles laid down prior to their incorporation into the fibrous system and its mineralization. This process looks more akin to neoplasia sensu (Zeitschrift für Wissenschaftliche Zoologie, 1858, 9, 147) than to metaplasia. Consequently, metaplastic and neoplastic processes may coexist in these ossicles with a possible differential expression during ontogeny.

Comparison of Rigid Pavement Planning Using PD T-14-2003 and NAASRA 1987 Methods in Industrial Areas

As vital infrastructure, roads are a means of transportation access and function as a distribution route for goods and services. Road pavement plays a crucial role in highway construction, necessitating proper planning according to Indonesian standards and planning criteria to ensure smooth land transportation and provide comfort and safety for its users. This study aims to provide information on road conditions, drainage dimensions, and construction costs. Planning is crucial in every road construction design, particularly for rigid pavement, based on survey data collected from the road section. Numerous methods exist for calculating the design value of rigid pavement. We use the Pd T-14-2003 method and the NAASRA 1987 method (National Association of Australian State Road Authorities) to plan rigid pavement thickness in the industrial area of PT. Bukit Muria Jaya Kudus. The Pd T-14-2003 method yielded a JSKN of 4x107 and a CBR of 35% for the subgrade, resulting in a plate thickness of 150 mm. While the Naasra 1987 planning method achieved a JSKN of 6x107 and a CBR of 35% for the base soil, a plate thickness of 160 mm was obtained with a value of K = 80 kPa/mm. The reinforcement planning using the Pd T-14-2003 and Naasra 1987 methods involves longitudinal reinforcement D10 mm at a distance of 150 mm and transverse reinforcement D10 mm at 250 mm. The drainage dimensions at the cross-section location are width x height (1 m x 1 m), and the guard's height is 0.2 m.

Taguchi, Grey Relational Analysis, and ANOVA Optimization of TIG Welding Parameters to Maximize Mechanical Performance of Al-6061 T6 Alloy

This study presents a comprehensive investigation into optimizing Tungsten Inert Gas (TIG) welding parameters to enhance the mechanical performance of the widely used Al-6061 T6 alloy, specifically in a double V joint configuration with a plate thickness of 6 mm, for aerospace applications. The Taguchi method was employed to design the experiments, providing a robust framework for analyzing the influence of the electrical current, voltage, and gas flow rate on weld quality. Additionally, a Grey Relational Analysis (GRA) and an Analysis of Variance (ANOVA) were used to validate the optimal welding parameters and quantify the significance of each factor. The optimized parameters were determined to be an amperage of 180 A, a voltage of 18 V, and a gas flow rate of 10 L/min, resulting in significant improvements of up to 40% in tensile strength and 23% in hardness, demonstrating the effectiveness of the optimized conditions. The findings provide valuable insights into welding metallurgy, offering practical guidelines for enhancing high-performance welded joints in critical industrial applications. This study underscores the potential of combining Taguchi, GRA, and ANOVA methodologies to achieve superior mechanical properties and reliability in welded structures.

A New Method for Measuring Multilayer Thickness Using a Chromatic Confocal Sensor

Multilayer transparent plates play a crucial role in industrial fields, such as optical lenses, electrodes, and solar panels, because of their superior optical and electrical properties. The thickness and uniformity of such plates are decisive for the quality of the final product. However, traditional contact measurement methods are inadequate in accuracy and pose the risk of damaging the plates, making nondestructive measurement of multilayer transparent plate thickness rather challenging. A new measurement technology is urgently needed. This study proposes a new method for the thickness measurement of multilayer transparent plates based on chromatic confocal sensor technology. First, we investigated the dispersive behavior of light in various media layers and derived theoretical measurement models for single-layer and multilayer transparent plate thicknesses. Subsequently, we designed and constructed a measurement system using a C-series chromatic confocal sensor and optical instruments and prepared a five-layer transparent sample consisting of quartz and air layers to confirm the feasibility of the method. The results of the experiment show that the proposed method can accurately measure the thickness of the five-layer sample with a maximum absolute error within 13 µm and a maximum relative error of 4.27%, thus proving its validity, precision, and stability. The results further indicate the high practicality and reliability of this technology in production environments, theoretically enabling the simultaneous measurement of up to 18 layers of the plate and offering broad application prospects in the industry.

Optimization of Rotary Drilling Rig Mast Structure Based on Multi-Dimensional Improved Salp Swarm Algorithm

The mast is a critical component of rotary drilling rigs, which has a cross-section consisting of a rectangular shape formed by two web plates and two flange plates. Structural optimization of the mast is necessary to address the issue of excessive weight. The shortcomings of the traditional structural optimization algorithms are summarized as follows: the optimized steel plate thickness is a non-integer, where rounding upwards may increase the cost to a certain extent, but it can ensure the safety of the structure; rounding downwards its load carrying capacity may not satisfy the requirements, and thus a novel Salp Swarm Algorithm is proposed to solve the optimization problem. First, this study improves the initialization and update strategy in the traditional Salp Swarm Algorithm. In order to obtain a solution for engineering, an innovative multi-dimensional running comparison is carried out. Secondly, the optimization model of rotary drilling rigs is established based on the division of the working conditions. The objective function of the optimization model is to minimize the weight of the mast while considering the constraints of strength, stiffness, stability, and welding process. Finally, the proposed optimization algorithm and the established optimization model are applied to optimize the design of the mast for a rotary drilling rig. The empirical results demonstrate that the weight of the mast has been reduced by 20%. In addition, the Improved Salp Swarm Algorithm exhibits higher solution quality, faster iteration capability, and extreme stability in optimizing welded box sections compared to the conventional algorithm. The example shows that the Improved Salp Swarm Algorithm is applicable to the optimization problem of box sections.

Achieving microstructural homogeneity in the stir zone across thick AA6061 welds using self-reacting bobbin tool friction stir welding

This study focuses into strategizing the usage of self-reacting bobbin tool friction stir welding (SRBT-FSW) to obtain consistent microstructural homogeneity along the thickness of AA6061 aluminium alloy (AA) thick plates during welding. The SRBT-FSW technology, distinguished by its dual-shoulder design, represents a significant step forward in FSW by eliminating the requirement for a backing anvil and promoting balanced heat distribution. This study seeks to address the issues of maintaining uniform microstructural characteristics throughout the weld zone, which is crucial for the mechanical performance and durability of welded joints in structural applications. The experimental study entails the systematic welding of AA6061 plates of 6 mm thickness using a self-reacting bobbin tool under a fixed processing condition. Electron backscatter diffraction (EBSD) was used to characterize the grain structure and phase distribution over the weld. Mechanical parameters like as tensile strength and hardness were determined to establish correlations between microstructure and mechanical performance. The results demonstrated that SRBT-FSW significantly enhances microstructural homogeneity across the weld zone, leading to improved mechanical properties. In the Bottom Zone (BZ), a refined grain structure with an average grain size (AGS) of 3.53 µm and a random or weak texture was observed, contributing to enhanced hardness and mechanical performance, with an ultimate tensile strength (UTS) of 220 MPa. In contrast, the Top Zone (TZ) exhibited a coarser AGS of 4.33 µm with a pronounced {111} crystallographic texture, resulting in a slightly lower UTS of 205 MPa. The Middle Zone (MZ), influenced by the greater heat input from both the TZ and BZ, showed an intermediate AGS of 3.99 µm, predominantly oriented along the {101} plane, and achieved a UTS of 194 MPa, with a slight reduction in ductility. This study highlights the potential of self-reacting bobbin tool friction stir welding as a reliable method for making high-quality, homogeneous welds in thick aluminium plates and paving way for their wider application in the aerospace, automotive, and shipbuilding industries, where homogeneous microstructural qualities are of significant importance.

Effects of TRIP and TWIP mechanisms on improved Charpy impact energy of thick hot-rolled duplex lightweight steel plates

Charpy V-notch impact testing serves as a fundamental method for assessing the toughness of conventional steels, but its applicability becomes challenging for duplex (δ-ferrite + γ-austenite) lightweight steels due to their complex microstructures and varied deformation mechanisms. In this study, Charpy absorbed energies of hot-rolled duplex lightweight steel plates, incorporating both transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) mechanisms, were investigated to understand their fracture behavior comprehensively. The microstructural analysis revealed that the D4 (0.4C-15Mn-6Al (wt.%)) steel exhibited lower δ-ferrite volume fraction and superior Charpy absorbed energy than the D2 (0.2C-15Mn-6Al) steel, attributed to its dominance of TWIP mechanism. Conversely, the D2 steel, with many ferrite/austenite interfaces, showed lower strain hardening and absorbed energy. At lower temperatures, both TWIP and TRIP mechanisms operated, but dominant TRIP mechanism along with higher δ-ferrite volume fraction in the D2 steel accelerated crack propagation, further reducing absorbed energy. The superior toughness of the D4 steel, driven by the dominant TWIP mechanism at lower temperature, highlighted its potential for practical utilization of thick hot-rolled lightweight steel plates in automotive, shipbuilding, military, and construction industries.

Development of a flat cutoff probe covered with a dielectric layer for non-invasive plasma diagnostics

Abstract Herein, we investigated the effect of a dielectric film on the transmission spectrum of a bar-type flat cutoff probe (BCP). By conducting electromagnetic wave simulations, we found that placing a dielectric film with a thickness of 1 mm or less on the sensor did not affect the measurement of the BCP under thin sheath condition. However, a film thickness of 1 mm or more results in a low-frequency shift in the cutoff frequency. The shift in the cutoff frequency was related not only to the film thickness, but also to the dielectric constant of the film and sheath width, which could be understood through a circuit model of the BCP. The calculated results were experimentally validated using alumina plates of various thicknesses. Consequently, our findings demonstrate that measuring the electron density on a BCP is feasible even when a dielectric film is deposited, thereby improving the accuracy of the measurement.