Thick Steel Plates Research Articles

The Use of Geotextiles for Controlling on The Collapse of Gypseous Soils

Gypseous soil is classified as problematic soil, characterised by its characterized by complicated and erratic behavior, and is mostly found in arid and semi-arid areas of the globe. As for Iraq. Gypseous soils cover about 30-35% of the total area of Iraq, as this type of soil is found in the Western Desert and extends to the southern parts of the country. Gypseous soils are considered strong but susceptible to sudden collapse when wet. To control the collapse of gypsum soils, Geotextiles are among the most popular kind of geosynthetic material used for soil reinforcement. The goal of this study is to determine whether woven geotextiles can improve the ultimate bearing capacity of foundations constructed on gypsum soil. The foundation is built from a strong 10mm thick steel plate measuring 100mm x 100mm. In this study, the depth of the geotextile layer that was placed at depths of (0.1B, 0.2B, 0.4B, 0.8B, B) was determined from the width of the foundation used, the number of layers of the reinforcement material (one layer, two layers, and three layers), and the layer-to-layer vertical spacing. Geotextiles: The geotextiles' breadth was also examined. The trials' findings demonstrated that adding geotextile reinforcement to soil can help it have a higher bearing capacity. and reduce the settlement of the gypsum soil. It was found that placing geotextiles at depths of (0.8B-B) is the best depth chosen, and the results were also revealed. The test showed that using three layers of geotextile gave positive results. Additionally, the test findings demonstrated that the reinforcement's composition had a significant impact on the behavior of the foundation

Oxyacetylene Flame Forming of Thick Steel Plates

One of the most widely used processes in ship hull plate manufacturing is the flame forming process (FFP). In this work, the fabrication of saddle-shaped specimens with FFP using a spiral irradiating pattern is studied experimentally. The deformation of the deformed plates by FFP based on the spiral irradiating pattern is affected by process parameters such as the pitch of spiral passes (PSP), the radius of the starting circle (RSC), and the number of irradiation passes (NIP). However, in this work, the effects of process parameters on the deformation of SSS are statistically examined by the design of experiment (DOE) method based on response surface methodology (RSM). The experimental and statistical results show that the deformation of flame-formed SSS increases with the increase in RSC and NIP and the decrease in PSP. In addition, the results of the optimization procedure demonstrate that the maximum value of deformations of flame-formed saddle-shaped specimens is achieved by adjusting the process parameters as follows: PSP = 10 mm, RSC = 75 mm, and five NIPs.

Impact of weld pool geometry on the welding temperature field of 50mm thick Q460-GJ steel plates

Abstract This article utilizes finite element software to calculate and analyze the impact of the molten pool geometry on the welding temperature field during the multi-layer and multi-pass welding process of Q460-GJ steel plates. Addressing the issue of how the molten pool shape affects the peak temperature and temperature distribution of each weld pass during welding, a finite element simulation was conducted for a thick plate with seven layers and 22 weld passes using numerical simulation. By adjusting the size of the double-ellipsoidal heat source model, finite element results considering the impact of the molten pool geometry were obtained. The results show that in the model without considering the molten pool geometry, the temperature of each weld pass ranges from 900°C to 2400°C, with 85% of the area having a temperature higher than 1500°C. In contrast, in the model considering the molten pool geometry, the temperature of each weld pass ranges from 2000°C to 2200°C, with 100% of the area having a temperature higher than 1500°C. The results considering the molten pool geometry are more consistent with the actual conditions.

Numerical simulation of 50mm thick Q420 steel plate welding with multi-layer and multi-pass welding process

Abstract This study uses finite element software to simulate and analyze a multi-layer, multi-pass (seven layers and twenty-two passes) welding technique applied to V-groove butt weld for 50mm thick Q420 steel plates. The simulation accurately depicts the temperature distribution during the welding process using a double ellipsoid heat source model. Temperatures gradually increase along each weld pass trajectory until reaching peak values exceeding 2000°C at specific points, while the underlying base metal reaches temperatures as high as 300°C. By examining metallic phases’ spatial allocation and compositional characteristics alongside thermal distribution after extensive welding simulations, these findings provide valuable insights for optimizing multi-layer, multi-pass welding procedures related to Q420 steel plates.

Improved singular spectrum decomposition method for resonance recognition of air-coupled ultrasonic signals in through-transmission steel plate detection

Abstract Air-coupled ultrasonic resonance detection is an emerging technique that eliminates the need for coupling agents in conventional ultrasonic testing and has a wide range of applications. However, this technique faces challenges, such as weak signal strength and susceptibility to noise, primarily due to the mismatch of acoustic impedance at the air–solid interface and sound attenuation in the air. This study proposed an improved signal processing method based on singular spectrum decomposition (SSD), optimizing the frequency components of each iteration using singular spectrum analysis. Additionally, a weighted Hurst exponent was introduced as a selection criterion to identify useful components and reconstruct the signal. Simulation results demonstrated the effectiveness of this method in denoising components and extracting weak resonance frequency features, especially in low signal-to-noise ratios (SNRs). Compared with conventional SSD and empirical mode decomposition, the proposed method improved the SNR by 39.4% and 301.33%. Furthermore, repeated experimental studies on steel plates with varying air lift-off distances and thicknesses confirmed that the proposed method could effectively reduce noise, thereby enabling accurate measurement of steel plate thickness.

Study on the parameters of steel plate reinforcement rib-deck crack considering local stress disturbances

Local reinforcement will change the local stiffness distribution of the component, causing perturbation effects on the local stress of the fatigue detail. Only considering the reinforcement effect may lead to excessive strengthening and induce new fatigue-prone points. For the fatigue detail of the rib-deck weld, steel plate reinforcement test and numerical simulations were conducted. The stress changes of the deck weld toe and weld root before and after reinforcement were analyzed. The influence of parameters such as steel plate length, thickness, and width on the reinforcement effect of the weld toe crack and local stress disturbance was discussed, and reasonable parameters were recommended. The results show that after the cracking of the weld toe, the stress concentration locations at the weld toe and weld root of the deck shift from the center of the specimen to the crack tip. Steel plate reinforcement can effectively restrain the crack propagation, but can lead to an increase in the stress at the deck weld root within the reinforced area. A good reinforcement effect can be achieved while the steel plate covers the crack, and further increasing the steel plate length has limited improvement on the reinforcement effect but reduces the adverse effect of steel plate reinforcement on the stress of the deck weld root. Increasing the steel plate width will increase the adverse effect of steel plate reinforcement on the deck weld root stress, and it is recommended to use steel plates with a length greater than 120 mm and a length-to-width ratio greater than 4 for reinforcement. Increasing the width of the steel plate has a relatively small effect on the reinforcement effect and the stress at the deck weld root, and steel plates with the same thickness as the deck are recommended.

Hysteretic Performance of Composite Damper with Yielding Reserve Stiffness

Previous research on composite dampers has rarely addressed the issue of large deformations of structures under limit state. However, the proposed damper in this paper takes this issue into account and could provide yielding reserve stiffness for structures, ensuring structural resilience. A composite damper with yielding reserve stiffness (YRSD), consisting of a friction unit and a metal yield unit, was proposed. Low cyclic loading tests with different energy-dissipating steel plate thicknesses and bolt preloads were carried out and experimental results were compared with that of numerical simulation. This paper focuses on the synergistic energy dissipation mechanism of the proposed damper and the effects of various factors on its hysteretic performance, including the bolt preload and thickness of X-shaped steel plates. The results show that the synergistic energy dissipation mechanism of the proposed damper is well, exhibiting the behavior of hardening post-yielding stiffness and multi-stage energy dissipation characteristics, which could provide yielding reserve stiffness for the structure. The experimental hysteresis curve of YRSD is full, indicating its strong energy dissipation capacity, and the skeleton curve of experiment is consistent with that of the theoretical model. The envelope area of the rectangular hysteresis curve of YRSD increases by 107.3% with the preload increased by 100%. When the thickness of the X-shaped steel plates is increased by 2 mm, the resistance of YRSD increases by 26.2% and the post-yield stiffness increases by 37.9%. The stiffness degradation trend of all specimens initially decreases and then increases. The energy dissipation capacity of the friction unit increases by 53.8% as the preload is doubled. The capacity of the metal yield unit increases by 31.7% as the thickness of the X-shaped steel plates is increased by 2 mm. When the energy dissipation capacities of the friction unit and the metal yield unit are close to equal, the optimal energy dissipation capacity of the proposed damper is achieved. The error of results between the numerical analysis and experimentation is less than 10%, providing a basis for the parametric analysis of similar composite damper with yielding reserve stiffness.

Ship Hull Steel Plate Deformation Modeling Based on Gaussian Process Regression

The linear heating and formation of steel plates is one of the most critical technologies in shipbuilding. Excellent technology not only provides good hydrodynamics for the hull but also affects the whole hull construction cycle and cost. In the heating and formation of a steel plate, the material, size, and thickness of the steel plate; heating temperature; heating position; and many other factors affect the formation of a steel plate. It is a very difficult process to know the influence relationship between various factors. In this study, a steel plate model is established by the Gaussian regression method, which can predict the steel plate deformation according to the selected steel plate material, size and thickness, heating temperature, and heating position. The accuracy of the model was evaluated, and the Gaussian process regression model has a better accuracy compared to other machine learning algorithm models. Finally the model visualization; designing the UI; selecting the steel plate material, size, and thickness; and inputting the heating temperature, the deformation magnitude, and stress magnitude of the steel plate can be obtained. The model can provide guidance to field workers for the heating and formation of hull steel plates and achieve efficient and fast formation of target steel plates.

Enhancing Welding Productivity and Mitigation of Distortion in Dissimilar Welding of Ferritic-Martensitic Steel and Austenitic Stainless Steel Using Robotic A-TIG Welding Process

The P91 martensitic steel and 304L austenitic stainless steels are two mainly used structural steels in power plants. The major problem in conventional multipass tungsten inert gas (TIG) welding of P91/304L steel is high heat input and joint distortion, increased cost and time associated with V groove preparation, filler rod requirement, preheating and welding in multiple passes, and labor efforts. Hence, in this study, a novel approach of robotically operated activated flux TIG (A-TIG) welding process and thin AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) sheet as the interlayer was used to weld 6.14 mm thick P91 and 304L steel plates with 02 passes in butt joint configuration. The joints were qualified using visual examination, macro-etching, X-ray radiography testing and angular distortion measurement. The angular distortion of the joints was measured using a coordinate measuring machine (CMM) integrated with Samiso 7.5 software. The quality of the A-TIG welded joints was compared to the joints made employing multipass-TIG welding process and Inconel 82 filler rod in 07 passes. The A-TIG welded joints showed significant reduction in angular distortion and higher productivity. It showed a 55% reduction in angular distortion and 80% reduction in welding cost and time compared to the multipass-TIG welded joints.

The penetration crater characteristics of thick steel plate impacted by tungsten alloy projectiles

Abstract The mild steel target plates impacted vertically by tungsten spherical projectiles with different initial velocities and projectile diameters were studied by ballistic experiments and numerical simulation. The macroscopic properties of the penetration crater were analyzed by the depth, diameter, and overall shape of the crater. The results show that crater diameter and depth increase as initial velocity or projectile diameter increases. With the increase in velocity, the deformation and erosion of tungsten projectiles significantly increased. Specific kinetic energy is used to normalize the velocity and size of the projectile, the expression of crater depth and diameter varying with specific kinetic energy is given, which accuracy R2 is 0.8. Based on THOR theory and experimental data, the accurate calculation model of penetration depth versus projectile mass, initial velocity, and the area of the contact was obtained, with an accuracy of R2 of 0.97.

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.

Passive vision based three-dimensional seam tracking using a stereo vision system with a single HDR camera

Seam tracking is a crucial feature that an automatic welding system must have. The laser tracking algorithm offers high accuracy but faces challenges in identifying seams with extremely narrow gaps, as the deformation of the laser stripe becomes difficult to detect in such cases. In contrast, the passive vision-based algorithm can effectively capture narrow gap information from the welding scene, making it more suitable for recognizing narrow seams. However, most of proposed passive vision-based seam tracking is based on “teaching and playback” mode and can only realize planar tracking. In medium and thick steel plate welding, the workpieces are so large that the “teaching and playback” based control algorithm is unsuitable. Therefore, in this paper, a stereo vision system with a single camera and the corresponding calibration algorithm are developed to achieve three dimensional seam tracking. Compared to stereo system with dual camera, the proposed system is cheaper and easier to synchronize acquisition. Moreover, to get out of the “teaching and playback” control strategy, a vector control algorithm without cumulative error is proposed. Results of nine experiments show that the average error of the proposed seam tracking system is less than 1.0662mm and the maximum error is 1.8030mm.

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.

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.

Modification and experimental validation of the Forrestal-Warren Perforation Model for high hardness armor steel plates of intermediate thickness

This paper proposes a modification of the Forrestal-Warren perforation model aimed at extending its applicability range to intermediately-thick high-hardness armor steel plates. When impacted by armor-piercing projectiles, these plates tend to fail through adiabatic shear plugging which significantly reduces their ballistic resistance. To address this effect, an approach for determining effective thickness was defined and incorporated into the predictive model. Ballistic impact tests were performed to assess the modification’s validity, in which ARMOX 500T steel plates were subjected to perpendicular impacts from 7.62 mm×39 mm steel-cored rounds under various velocities. Frequent target failure by soft plugging was observed, as well as the brittle shatter of the hard steel core. Key properties of the recovered plugs including their mass, length and diameter were measured and reported along with the projectiles' residual velocities. Additionally, independent data from the open literature were included in the analysis for further validation. The original Forrestal-Warren model and the novel effective thickness modification were then used to establish the relationship between impact and residual velocities, as well as to determine the ballistic limit velocity. The comparison revealed that the proposed approach significantly improves the model's accuracy, showing a strong correlation with experimental data and reducing deviations to within a few percent. This enhancement highlights the potential of the effective thickness term, which could also be applied to other predictive models to extend their applicability range. Further exploration into other armor steels and impact conditions is recommended to assess the method's versatility.

Dissimilar unbeveled aluminum to steel butt joint achieved by laser-arc hybrid welding-brazing

In this study, unbeveled butt joints of 2 mm thick steel and aluminum plates were welded using a laser-arc hybrid process. The influence of welding speed and wire feed speed on joint weld formation, microstructures, and mechanical properties were investigated. The results indicate that using a laser-arc hybrid heat source enables good weld formation of steel/aluminum dissimilar metals without groove preparation, even under high welding speed conditions. The steel side interface formed Fe₂(Al,Si)₅ near the steel and Fe(Al,Si)₃ near the aluminum. As the welding heat input decreased, the thickness of the intermetallic compounds gradually reduced. With an increase in welding speed or wire feed speed, the tensile strength of the joint first increased and then decreased, reaching a maximum of 104.47 MPa. Cracks propagated rapidly along the intermetallic compound region, resulting in brittle fracture characteristics. The three-point bending test showed a maximum longitudinal bending angle of 53.82° and a maximum transverse bending angle of 36.54°.

Tension performance of joint made in cold-formed square tube with self-tapping screw connections

The tension behavior of cold-formed square tube (CFST) screw connections was investigated experimentally and numerically. Ten test specimens were fabricated from the square tubes connected by external steel plates and internal tube applying self-tapping screws such that the number of screws was varied. In addition, the mechanical properties of the single-screw connections were obtained through single shear tests. Experimental results revealed that an increase in the number of screws led to higher bearing capacity and stiffness in the specimens. Shear failure of the screws was observed as the primary failure mode. When the number of the screws was equal in both types of the specimens, those with the internal tube exhibited superior tensile behavior than the ones with external steel plates. Subsequently, finite element (FE) models of the test specimens were developed. Upon validation of the test results, an extensive parametric study was conducted to further examine the influence of the design parameters on the tensile behavior of the CFST screw connections. Variation of the arrangement of screws, wall thickness of steel plates and their strength had only a minor influence on the tension behavior, and steel strength had little influence on the tension behavior and the number, spacing, and diameter of the screws were the key parameters affecting the tension behavior of the CFST screw connections. Based on the test results and FE analyses, the existing calculation method was modified, and a formula for calculating the tensile bearing capacity of the CFST screw connections was obtained. Comparison with the results indicate that the formula was conservative and reliable for determining the tensile capacity of CFST screw connections.

Thermal creep strain test and model of Q460GJ steel at elevated temperatures

Q460GJ steel is a typical high strength and high-performance structural steel. The thermal creep test on two thicknesses (8 mm and 12 mm) of Q460GJ steel plates at elevated temperatures (400–800 °C) was carried out. The test results showed that the thermal creep strain increases with the increases of temperature and stress. When the temperature exceeds about 500 °C and the stress ratio is greater than about 0.55, the Q460GJ steel plate specimens has obvious creep deformations, so it is necessary to consider the thermal creep deformation of steel at elevated temperatures for steel structural design. The difference in plate thickness does not affect the creep properties of the 8 mm and 12 mm Q460GJ steel plates at elevated temperatures. When the temperature is no more than 600 °C, the second stage creep strain rates of Q460 steel are obviously higher than that of Q460GJ steel while the stress levels are close. The Fields & Fields creep model is suitable for fitting the thermal creep strain-time curves for Q460GJ steel. The findings will contribute to providing theoretical support for design of high-performance steel engineering structures under fire.

Seismic Behavior of Concrete Beam-Column Joints Reinforced with Steel-Jacketed Grouting

Joints in frame structures often fail before beams and columns in an earthquake and are a key part of reinforcement. In this study, to enhance the seismic performance of concrete frame structures, a steel-jacketed grouting composite reinforcement method is proposed by combining reinforcement technology, steel cladding technology, and eco-efficient materials from grouting technology. This method effectively utilizes the advantages of various materials, avoids major demolition and construction, and reduces waste and resource consumption. In order to verify the feasibility and effectiveness of the reinforcement method, one of the original joint specimens with a scale of 1:3 and one of the reinforced joint specimens were designed and tested. The experiments involved reversed cyclic testing of beam–column to measure its seismic behavior. The seismic performance indexes such as failure characteristics, hysteretic properties, and the energy dissipation capacity of the specimens were analyzed, and the corresponding finite element model was established. The influence of key parameters such as reinforcement range, steel plate thickness, and grout strength on its seismic performance was explored. The research shows that the method can effectively improve the seismic performance of the joints, and seismic performance indexes such as bearing capacity, ductility, and energy consumption of the specimens are significantly improved. The test results of the established finite element model are in good agreement. The variable parameter analysis of the finite element shows that the thickness of the steel plate has little influence on its bearing capacity. With the increase in the reinforcement range of the clad steel and the strength of the grouting material, the bearing capacity of the specimen increases. The research results can provide a reference for the reinforcement of frame structure joints.

The shear performance of DSCW-RC joints with lap-spliced steel bars

The double steel plate concrete composite shear wall (DSCW) structure combines the advantages of steel and concrete, offering high strength, stiffness, and durability. The joint formed by the DSCW and reinforced concrete foundation (RC foundation) was often unavoidable in engineering practice. Research related to the mechanical behavior of the DSCW-RC foundation is limited. This paper investigated the shear performance of DSCW-RC joints with lap-spliced steel bars. A total of seven specimens were designed and tested. The influences of steel plate thickness, steel bar arrangement, and stud spacing on the shear behavior of the joints are elucidated. The test results indicate that the predominant failure mode of the specimens occurred in the upper part of the local steel plate, with reinforcement yielding. While steel bar diameter and stud spacing minimally affected the shear strength, they significantly influenced the failure displacement at the joint interface. The failure deformation increased with increasing steel bar diameter and decreased with increasing stud spacing. Moreover, the thickness of the steel plate profoundly impacted structural shear strength and deformation, with both deformation and bearing capacity increasing with plate thickness. In addition, this study explores the force-transferring mechanism of such joints under shear load, offering a crucial reference for subsequent analyses of the composite force mechanism of DSCW - RC foundation joints.