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In this paper, dissimilar aluminum (Al) and copper (Cu) metals were joined together using ultrasonic metal welding (USMW), a solid-state welding technology. From the perspective of increasing the base metal welding contact area, the Cu/Al mating surface was innovatively prepared and ultrasonically welded. A comprehensive analysis was carried out on the forming quality, welding process temperature, interface structure, and mechanical properties of the welded joint. Defect-free and squeezed welds were successfully achieved by machining novel patterns especially C4-2. The results indicated that the reference joint can withstand higher loads, but its failure mode is very unstable. Failure may occur at welded interface and on the aluminum plate which is not good for actual production applications. Welded strength of reference joint was 4493 N, and the welded strength of C4-2 joint was 3691 N. However, microscopic analysis discovered that the welded joint internal morphology in C4-2 was more stable and hardest. C4-2 joint has successfully achieved higher tensile strength and stability under failure displacement of 38% which is higher than C4-1 joint. All welded joint failures occurred on aluminum plate, indicating that the joint strength is higher than that of bottom plate. This is attributed to unique structural design of chiseled joint and lesser thickness. SEM–EDS results investigated that the C4-2 joint can transfer more energy to area under welding head which provides welded joint with robust diffusion capacity. The transition layer has a higher thickness while the energy transferred to area away from welding head was smaller. Thickness of transition layer is significantly reduced and reference joint has similar diffusion characteristics. Conversely, the thickness of the transition layer at the corresponding position is smaller than that of pattern morphology. This is due to overall smaller thickness of the pattern joint which is more conducive to the transfer of welding energy. The surface-conformed approach and comprehensive temperature analysis provide a new understanding of USMW in dissimilar welded metals.

In this work, a new attempt was made to study the behavior of the conventional solar still (CSS) by adding a black-painted copper plate and phosphate pellets. Therefore, the performance of the three solar stills has been studied and compared. The first is the CSS, and the second is the modified solar still (MSS). The MSS performance was tested using black-coated copper plate (measuring 49 × 49 cm and 0.2 cm thick) with and without phosphate pellets and compared to the CSS in the similar climatic conditions. The results showed that the combination of black coated copper plate and the inclusion of phosphate pellets improved the evaporation rate and daily productivity. During the experiments, yields using black coated copper plate without and with phosphate pellets were 14.96% and 29.53% greater than the CSS. The effectiveness of the CSS, MSS with copper metal plate (MSS-CP), and MSS with copper metal plate with phosphate pellets (MSS-CP and PP) are around 30.23, 35.3, and 41.44%, respectively.

Due to its high-quality weld seam and excellent arc stability, narrow gap Tungsten Inert Gas (TIG) welding has become a critical technology for welding thick metal plates. However, this technology has the problem of insufficient sidewalls penetration, which has a significant impact on the performance of the components. This study provides a comprehensive overview of three optimization methods, including mechanical improvement, field control, and composite welding. It critically analyzes the principles and research status of each method. The advantages and disadvantages of these methods have been summarized. In Outlook, application scenarios for auxiliary processes have been presented. Further, there is a prospect for the development of an ultra-long arc narrow gap TIG welding process.

Background Fractures involving the posterior acetabulum with its rich vascular and neural supply present challenges in trauma orthopedics. This study evaluates the effectiveness of 3D printing technology with the use of custom-made metal plates in the treatment of posterior wall and column acetabular fractures. Methods A retrospective analysis included 31 patients undergoing surgical fixation for posterior wall and column fractures of the acetabulum (16 in the 3D printing group, utilizing 3D printing for a 1:1 pelvic model and custom-made plates based on preoperative simulation; 15 in the traditional group, using conventional methods). Surgical and instrument operation times, intraoperative fluoroscopy frequency, intraoperative blood loss, fracture reduction quality, fracture healing time, preoperative and 12-month postoperative pain scores (Numeric Rating Scale, NRS), hip joint function at 6 and 12 months (Harris scores), and complications were compared. Results The surgical and instrument operation times were significantly shorter in the 3D printing group ( p  < 0.001). The 3D printing group exhibited significantly lower intraoperative fluoroscopy frequency and blood loss ( p  = 0.001 and p  < 0.001, respectively). No significant differences were observed between the two groups in terms of fracture reduction quality, fracture healing time, preoperative pain scores (NRS scores), and 6-month hip joint function (Harris scores) ( p  > 0.05). However, at 12 months, hip joint function and pain scores were significantly better in the 3D printing group ( p  < 0.05). Although the incidence of complications was lower in the 3D printing group (18.8% vs. 33.3%), the difference did not reach statistical significance ( p  = 0.433). Conclusion Combining 3D printing with individualized custom-made metal plates for acetabular posterior wall and column fractures reduces surgery and instrument time, minimizes intraoperative procedures and blood loss, enhancing long-term hip joint function recovery. Clinical Trial Registration 12/04/2023;Trial Registration No. ChiCTR2300070438; http://www.chictr.org.cn .

Deep rock masses exist in a complex environment with multi-field coupling; therefore, it is necessary to develop a true-triaxial static-dynamic-coupling loading test machine to explore their characteristics and mechanical response mechanism. To meet the test requirements of true-triaxial loading and strong disturbance, a wave-absorbing metal plate was selected as the boundary material between the granite and transmission end, and the modified SHPB was used to perform static-dynamic-coupling loading tests. In this study, two series of experiments on wave- absorbing metal plates were conducted, which were fixed aperture sizes with different thicknesses and fixed thicknesses with different aperture sizes. The static-dynamic-coupling loading tests on each aperture size and plate thickness were carried out under the condition of equal energy impact. The effects of the aperture size and plate thickness on the incident- and reflection-stress curves, reflectivity, energy consumption law, energy evolution, and other mechanical properties of the wave-absorbing metal plate materials were studied. The results show that the peak stress and reflectivity decrease with increasing aperture size and plate thickness, and the influence of the thickness is greater than that of the aperture size. The energy-absorption rate of the wave-absorbing metal plate increased with increasing thickness and aperture size and was maximized when the aperture size and thickness were 6–7 mm and 3–4 mm, respectively. The variation trend of the energy reflectance is opposite to that of the energy absorption and reaches a minimum when the aperture size is 6–7 mm and plate thickness is 3–4 mm. The energy transmittance of the wave-absorbing metal plate fluctuated in a stable range, but the variation range was less obvious compared to that of the energy-absorption rate.

Generally, the thickness of thick metallic plates is measured by exploitation of some physical phenomenon outside of eddy currents which are naturally limited for thin plates with respect to the skin effect. Indeed, it is the capacitive or ultrasound sensors which are the commonly used for thick plates. This paper proposes an alternative for thickness evaluation of thick metallic plates using eddy currents. The measurement system consists mainly of two eddy current sensors, an impedance analyzer LCR-meter and a personnel computer equipped with the Labview software. The plate we want to measure its thick thickness is placed between the two sensors. The proposed measurement procedure is based on lift-offs evaluation of a bi-eddy current sensor. The system has been verified and validated with success using several thick aluminum plates. The realized experimental setup can be used for online thickness measurement in some industrial applications.

Perforated cylindrical shaped metal plates are used with high efficiency in the manufacture of deflectors, components of cooling systems, wind tunnels, climatic chambers, filters, and cylindrical implants. This is particularly important for lightweight cylindrical structures, where even minor changes in stiffness can affect structural strength. One of the most important parameters determining the mechanical behavior of such structures is the effective elastic modulus of the perforated element which characterizes its resistance to deformation. The research involves plates made of stainless steel 304 alloy, where perforations were created using the laser-cutting method. The cylindrical shape of the samples with height 50 mm, thickness 1 mm, and diameter 48 mm of each specimen was obtained using metal rolling and welding techniques. To determine the effective elastic modulus, a non-destructive material property evaluation method was applied by solving an inverse problem. In this research, resonance frequencies were determined using a laser vibrometer and a full factorial experimental plan was developed. Physical samples were digitized into 3D models using 3D scanning technology. To evaluate the accuracy of the applied finite element numerical model, its convergence analysis was performed. Numerical results were approximated using the least-squares method, while the effective elastic modulus was calculated by formulating and minimizing the error functional between experimental and numerical eigenfrequencies. The results indicate that increasing the relative perforation area from 0% to 50.24% leads to a decrease in the effective elastic modulus from 184.76 GPa to 50.69 GPa, confirming that increasing the perforation area in a stainless steel 304 cylinder reduces its elastic properties. The observed reduction in resonance frequencies and elastic properties is primarily due to the stiffness decrease caused by the higher perforation volume.

This study presents a theoretical analysis of the perforation process of finite-thickness metal plates (with a thickness ratio of T0/D = 0.6–1.5) under normal impact by spherical-nosed projectiles. The model is validated over an impact velocity range of 180–1247 m/s. The entire penetration process is divided into three stages: the crater formation stage, the steady stage, and the shear stage. A thickness-dependent dynamic cavity expansion resistance model is first introduced to quantitatively describe the axial resistance experienced by the projectile during the tip-entry and steady stages. Subsequently, a thickness-related damage parameter is proposed to refine the resistance expression during the transition from the steady stage to the shear stage, thereby eliminating discontinuities in resistance across stages. When the projectile fully perforates the target, the model predicts a gradual decay of resistance to zero as the residual ligament thickness vanishes, which better reflects the actual physical behavior. The model is validated using four sets of experimental conditions. In addition, to illustrate the model's applicability more intuitively, a numerical simulation case from the literature is reproduced, and the resulting resistance-time curve is compared with the model output. The results demonstrate that the proposed model agrees well with experimental data in terms of residual velocity, ballistic limit, and penetration resistance. Finally, a method for adjusting the threshold parameter within the resistance function is provided, and the influence of this coefficient on the model predictions is discussed.

The process of wave formation at the contact boundary of colliding metal plates is a fundamental basis of explosive welding technology. In this case, the metals are in a pseudo-liquid state at the initial stages of the process, and from a mathematical point of view, a wave formation process can be described by compressible multiphase models. The work is devoted to the development of a three-fluid mathematical model based on the Baer–Nunziato system of equations and a corresponding numerical algorithm based on the HLL and HLLC methods, stiff pressure, and velocity relaxation procedures for simulation of the high-speed impact of metal plates in a one-dimensional statement. The problem of collision of a lead plate at a speed of 500 m/s with a resting steel plate was simulated using the developed model and algorithm. The problem statement corresponded to full-scale experiments, with lead, steel, and ambient air as three phases. The arrival times of shock waves at the free boundaries of the plates and rarefaction waves at the contact boundary of the plates, as well as the acceleration of the contact boundary after the passage of rarefaction waves through it, were estimated. For the case of a 3-mm-thick steel plate and a 2-mm-thick lead plate, the simulated time of the rarefaction wave arrival at the contact boundary constituted 1.05 μs, and it was in good agreement with the experimental value 1.1 μs. The developed numerical approach can be extended to the multidimensional case for modeling the instability of the contact boundary and wave formation in the oblique collision of plates in the Eulerian formalism.

Laser bending of elastic pre-loaded metal plates is promising due to many advantages, such as high forming precision and avoidance of plastic instability. To reveal the plastic deformation behavior of the plate, the deformation process is investigated through theoretical analysis and finite element (FE) simulations. The FE model is verified via forming experiments. The results show that the yield strength of the metal material decreases faster than the elastic modulus with the rising temperature of the plate during laser scanning. Then, the equivalent stress which is calculated to be proportional to the elastic modulus overtakes the yield strength in some regions of the plate, so that the plastic deformation occurs. The amount of the plastic deformation inside the plate can be estimated by an analytical formula derived in theory, and it depends on both pre-stress field and peak temperature field. Larger pre-stress and higher peak temperature bring about larger plastic strain. Because of this, for a point of any segment whose midperpendicular is the scan path in the present forming model, the closer position is to the scan path the larger x -axis direction plastic strain it would generate inside.