Deformation Plate Research Articles

Study on structural damage mechanisms and defence of rectangular closed-section simplified hull girders with thinner plates under near-field underwater explosions

Understanding the damage mechanisms of typical ship structures under fatal underwater explosion loads is crucial for developing effective defensive measures. To provide references for enhancing the survivability of ships, this paper conducts analyses of the damage mechanisms of simplified hull girders (SHGs) using a combination of experimental and simulation methods, and proposes targeted structural improvements. Initially, two types of thin-walled rectangular closed-section SHGs are subjected to near-field underwater explosion experiments. Corresponding simulation models are established, and the validity of the computational results is verified. The progressive damage processes of SHGs in hogging and sagging are examined from a structural perspective. Furthermore, the thin-walled plate deformation transfer processes are analyzed. Finally, based on the analyzed damage mechanisms, targeted defensive structures for overall damage are designed. The study results show that enhancing the anti-deformation capability of the upper and lower edges of the side plates can effectively improve the overall bending resistance of the SHG.

Experimental investigations of beam-column joints with replaceable BRFCPs using sliding restraint plates

This paper proposes a replaceable buckling-restrained flange cover plate (BRFCP) for steel beam-column joints with cantilever beam segments, in which a sliding restraint plate (SRP) with slotted holes is used to constrain the core plate buckling deformation and simultaneously control the restraint plate without significant damage. First, theoretical analyses and design considerations were presented for this joint. Second, cyclic loading tests were conducted on five joints with different BRFCP configurations, including different formats of restraint plates (discontinued or sliding restraint plates), filling plates (discontinued or sliding filling plates), and restraining gaps with different sizes. The test results showed that the damage of the proposed joint was visually observed only on the replaceable core plates and was not observed at any other structural components. The SRP can effectively constrain the buckling deformation of the core plate in comparison to the discontinued restraint plates; thus, the proposed joint showed more stable force–deformation hysteresis. The continuity of the filling plates and the restraining gap size had little influence on the overall hysteretic response of the joint. However, a larger restraining gap caused larger stress in the restraint plates. Finally, numerical models of the test joints were established in ABAQUS and validated by the test results, which can serve as a reference for further research.

In situ white mica Rb/Sr geochronology of the Leszczyniec metaigneous complex, West Sudetes: evidence of upper plate deformation at the onset of Variscan collision

The Karkonosze-Izera Massif in the West Sudetes preserves evidence of subduction of the Saxothuringian Ocean beneath the Teplá-Barrandian Domain. Within the massif, the Leszczyniec metaigneous complex (LMC) is identified as the upper allochthon. It exhibits a unique structural history in comparison to the underlying allochthons, suggesting that the LMC records a distinctive tectonic history. To investigate the timing of this history, two orthogneisses were studied from a single outcrop of the LMC for in situ white mica Rb/Sr geochronology. The outcrop bears a southeast-dipping foliation (S1) and a north/northeast plunging stretching lineation (L1), defined by white mica and quartz. Quartz recrystallization textures, white mica chemistry (celadonite content of 0.23–0.47), preservation of igneous plagioclase phenocrysts, and the metamorphic mineral assemblage, all indicate maximum epidote–amphibolite facies conditions. Single-spot Rb/Sr dates were calculated from white mica using initial 87Sr/86Sr values obtained by titanite and epidote. Results are similar for both rocks, providing weighted averages of 352.4 ± 4.1 Ma (MSWD: 0.6; n: 24) and 349.3 ± 2.5 Ma (MSWD: 0.4; n: 31). The rocks are interpreted to have the same structural and metamorphic history; thus, a pooled weighted average of 350.1 ± 5.3 Ma (2σ) is reported as the timing of white mica (re)crystallization during S1 and L1 development in epidote–amphibolite facies conditions. This event is bracketed by the timing of blueschist-facies metamorphism for the subjacent middle (c. 364 Ma) and lower (c. 345–341 Ma) allochthons, associated with an east/southeast-plunging L1. Considering the different structural and metamorphic histories of the LMC compared to the subjacent allochthons, it is likely that the complex was extracted from the Teplá-Barrandian upper plate due to subduction erosion prior to collective exhumation and stacking of the Karkonosze-Izera Massif.Graphical abstract

The role of subduction and gravitational collapse in driving extension in the Aegean Sea

The Aegean domain has experienced lithospheric deformation during continuous northward subduction at the Hellenic trench. Early Cenozoic shortening and thickening were followed by late Cenozoic extension and thinning. Thickened lithosphere, in particular its crust, has excess gravitational potential energy, which is thought to promote orogenic collapse (i.e., gravity spreading). In the Aegean domain, release of this potential energy and collapse of the lithosphere has been proposed as the first-order driver for extension of the overriding plate. Here we show, using dynamically self-consistent analogue experiments of subduction and gravity spreading, that the subducting plate significantly influences overriding plate deformation, despite the overriding plate being positively buoyant. With the introduction of a subducting plate, the trench retreat velocity and overriding plate extension rate increase, which is in contrast with a continuous decline during gravity spreading. In addition, ∼E-W trending normal faults emerge, as opposed to arc-parallel faults trending ∼ENE-WSW to ∼ESE-WNW and arc-normal extensional zones that result from gravity spreading only. Similarly, the subducting plate causes overriding plate displacement to be unidirectional (trenchward), in accordance with the present-day geodetic velocity field, whereas gravity spreading causes a radially outward-directed displacement field. As the decline in trench retreat rate, radial spreading, dominantly arc-parallel normal faults, and arc-normal extensional zones are not observed in nature, this implies that gravity spreading cannot be the sole driver of extensional deformation in the overriding plate. Indeed, the models suggest that subduction-induced mantle flow is the dominant driver of overriding plate deformation because it imposes a basal shear stress on the overriding plate, dragging and extending it trenchward in a unidirectional manner. Our experimental results corroborate earlier studies that highlight the important role of subduction-induced mantle flow in driving overriding plate deformation. Additionally, we find that this role is more pronounced in experiments with a thicker brittle layer.

New Method for Precise Measurement of Clamping Plate Deformations on Forming Presses

The deformation of press bolster plates under load can significantly impact the quality of manufactured workpieces. Consequently, press manufacturers are usually obliged to provide the metric proof of the permissible deformation values during the press commissioning process. Unfortunately, the existing measurement methods for determining bolster plate deformations present flaws in the measurement accuracy, the application flexibility, the metrological effort, and other aspects. These issues have been addressed through the development of a new measurement method using multiple inclination profiles on the surface of the measured object. Based on the difference in the inclination between the unloaded and loaded states, the method approximates the inclination surface and calculates the deformation of the measured object through integration. The measurement method was first used for commissioning tests of forming presses. A comparison with the results obtained with a measurement frame equipped with high-resolution measurement probes demonstrates an accuracy of the new method of less than 20 µm.

VALIDATED FINITE ELEMENT SIMULATIONS PREDICT OVERLOADING FAILURE OF OSTEOSYNTHESIS PLATES

Osteosynthesis aims to maintain fracture reduction until bone healing occurs, which is not achieved in case of mechanical fixation failure. One form of failure is plastic plate bending due to overloading, occurring in up to 17% of midshaft fracture cases and often necessitating reoperation. This study aimed to replicate in-vivo conditions in a cadaveric experiment and to validate a finite element (FE) simulation to predict plastic plate bending.Six cadaveric bones were used to replicate an established ovine tibial osteotomy model with locking plates in-vitro with two implant materials (titanium, steel) and three fracture gap sizes (30, 60, 80 mm). The constructs were tested monotonically until plastic plate deformation under axial compression. Specimen-specific FE models were created from CT images. Implant material properties were determined using uniaxial tensile testing of dog bone shaped samples. The experimental tests were replicated in the simulations. Stiffness, yield, and maximum loads were compared between the experiment and FE models.Implant material properties (Young's modulus and yield stress) for steel and titanium were 184 GPa and 875 MPa, and 105 GPa and 761 MPa, respectively. Yield and maximum loads of constructs ranged between 469–491 N and 652–683 N, and 759–995 N and 1252–1600 N for steel and titanium fixations, respectively. FE models accurately and quantitatively correctly predicted experimental results for stiffness (R2=0.96), yield (R2=0.97), and ultimate load (R2=0.97).FE simulations accurately predicted plastic plate bending in osteosynthesis constructs. Construct behavior was predominantly driven by the implant itself, highlighting the importance of modelling correct material properties of metal. The validated FE models could predict subject-specific load bearing capacity of osteosyntheses in vivo in preclinical or clinical studies.Acknowledgements: This study was supported by the AO Foundation via the AOTRAUMA Network (Grant No.: AR2021_03).

The influence of the variability of the support of the mortar base plate on the quality of the results obtained in the process of its numerical design

Due to the high costs associated with the purchase of ammunition and firing in certified training ground centers, tests of retaining plate deformations are increasingly replaced by computer simulations using numerical models. Computer programs usually use a single-parameter subsoil model (Winkler-Zimmermann) for calculations, which requires providing the subgrade susceptibility coefficient. The subgrade compliance coefficient is intended to determine the mutual reaction of the subgrade and the structure due to the pressure exerted on the soil by the retaining slab, which settles. When designing slabs in computer programs, it is assumed that the substrate compliance coefficient is constant. Determining the impact of the soil on the retaining slab is important when analyzing its deformations. The subject of the work was the analysis of the influence of ground support on the results obtained during modeling of the retaining slab. In order to obtain data for FEM analysis and validation, the actual strains occurring on the thrust plate were measured using strain gauge rosettes. The plate deformations were measured during field shooting tests. In order to vary the influence of supporting the slab on the ground and obtain reliable stress values on the slab surface, a method of successive iterations was proposed. Calculations are performed using this method until the error is smaller than the assumed one.

ИССЛЕДОВАНИЕ ПОЛЗУЧЕСТИ СТАЛЕЖЕЛЕЗОБЕТОННЫХ ОБРАЗЦОВ

The paper presents the results of investigation of creep and shrinkage of steel-reinforced concrete specimens. For this purpose, parallel tests of specimens made of the same class of concrete but with different reinforcement were carried out. Concrete specimens, specimens reinforced with bar reinforcement frames and steel reinforced concrete specimens with external sheet reinforcement were investigated. The tests were carried out in climatic rooms using spring setups to maintain a constant load acting on the specimens over time. The load on the specimens was selected based on the equality of stresses in the concrete in all series of specimens. The specimens were tested both waterproofed and non-waterproofed, and the effect of waterproofing coating on shrinkage and creep strains was evaluated for different series of specimens. A system was developed to capture information. which allows, in addition to longitudinal shrinkage and creep deformations, to determine transverse deformations, longitudinal deformations along the faces of the specimen to determine the influence of reinforcement and steel of the outer plate, to evaluate the change in longitudinal deformations from the center of the specimen to its edges, to evaluate separately the deformations of concrete and steel plate in steel-reinforced concrete specimens. The analysis of the results allowed a comparative assessment of the influence of conventional bar reinforcement as well as steel sheet of steel-reinforced concrete specimens on creep and shrinkage deformations; the influence of waterproofing coating on the test results in different series was also assessed. Based on the results of this work, extended requirements for experimental and theoretical studies of steel-reinforced concrete specimens with external sheet reinforcement to determine their design stiffnesses were formulated.

Modeling of deformation and fracture processes of unevenly heated round plate subjected to high-temperature hydrogen corrosion

The paper considers modeling of deformation and fracture processes of a round plate subjected to high-temperature hydrogen corrosion in a non-uniform temperature field. The influence of hydrogen-containing medium and temperature on the character of creep and fracture processes is taken into account in model building. The derivation of the solving differential equation of a non-uniformly heated circular plate is described.

Effect of component geometry on the dynamic thermal field generated in the laser forming of AA6061-T6 sheet

Laser forming (LF) technology is an advanced, highly customizable non-contact method for shaping metal sheets, characterized by its heightened precision and flexibility. This experimental and numerical study investigates the influence of component geometry on the dynamic temperature field arising from LF of AA6061-T6 sheet metal. Finite element models were constructed to analyse the dynamic temperature field variations in plates with different dimensions. The findings demonstrate the significant effect of sheet dimensions on the induced thermal field, that consequentially affect the deformation. In contrast to a stable heating and cooling profile observed in a 50mm-wide or greater sample, a 20mm-wide or smaller sample exhibits a temperature resurgence or reflection along the laser pathway. The deformation of the aluminium plate therefore decreases with the reduction in geometry size. The analysis of this thermal behaviour helps to explain this and further advances the understanding of the LF mechanism specific to high thermal-conductivity materials.

A study of plate motion and deformation of South Korea

A study of plate motion and deformation of South Korea

Aesthetic and functional corrections in case of foot plate deformities in rhinoplasty

Aesthetic and functional corrections in case of foot plate deformities in rhinoplasty

Double-layer sheets SPR-bonded hybrid joining method of an extendable die

To further improve the strength and quality of the Sheet connection and increase the traditional self-piercing riveted (SPR) interlocking, a self-piercing riveted-bonded (SPR-bonded) hybrid joining method for double-layer sheets based on an extendable die was proposed. Three kinds of heterogeneous sheets expandable die SPR-bonded hybrid forming rules were investigated. The mechanical properties and failure mechanisms of SPR, adhesive, and hybrid joints were compared. Results show that compared with the traditional SPR die, the expandable die can increase the joint interlocking value to a certain extent and thus improve the strength of the connection by delaying the deformation of the lower plate and guiding the rivets to flare twice. The forming load is low when magnesium alloy is used as the upper sheet. Joint stress concentration, strain concentration, and thinning of the lower sheet are light. From the point of view of the shear strength of each joint, the hybrid joints of the three types of sheet materials increased the shear strength of the joints by 11 %, 36 %, and 30 %, respectively, compared with their respective SPR joints. The existence of the adhesive layer in the hybrid joint can improve the overall strength of the hybrid joint on the one hand and delay the destruction of the interlocking structure in the hybrid joint on the other hand. In general, the combination of an extendable die and SPR-bonded hybrid could improve the overall strength and safety of the joint and can be used for joining heterogeneous sheets.

Numerical analysis and deformation prediction of a novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe

With the further reduction of the thickness of flat heat pipe, vapor–liquid coplanar flat heat pipe (CFHP) has been proven to be an effective method for thermal management system of electronic devices in limited spaces. The large-area, thin, and lightweight CFHP was of great importance for achieving thermal control of high-power outdoor telecommunication equipment. Thus, a novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe (HCFHP) was proposed in this work. Initially, a simplified three-dimensional numerical model was constructed to assess the thermal–hydraulic performance of HCFHP. Comparisons were made between the velocity, pressure, and temperature profiles of HCFHP and CFHP. The simulation results revealed a significant enhancement in the heat transfer performance of the optimized HCFHP structure. Notably, the total thermal resistance of HCFHP was reduced to 0.0567 K·W−1, representing a remarkable 94.144 % reduction compared to CFHP. Additionally, to meet the strength and deformation requirements of HCFHP under high saturated vapor pressure, thermal–mechanical coupling was considered. A fitting formula was developed to predict the maximum deformation of the thin plate between circular support structures within HCFHP. The mechanical simulation results were in excellent agreement with the formula calculations, with a mere 0.063 % relative error. This novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe could be a practical and highly efficient solution for thermal control of high-power telecommunication equipment.

Improving the quality of cold-rolled deformable aluminum alloy billets

A mode of high-speed recrystallization annealing has been developed to increase technological plasticity while maintaining the strength of sheet cold-rolled blanks made of deformable aluminum alloys that are not strengthened by heat treatment. Problem. Cold deformation of cold-rolled plates is achieved by recrystallization annealing in hooded furnaces. However, such annealing often does not provide the technological plasticity for defect-free stamping of products and, as a result, has significant rejects. Hooded furnaces are not suitable for improving the deformation of individual billets. In addition, for products with complex configurations that operate in harsh environments, the requirements for rolled aluminum are increased, which is also not possible to realize in open hearth furnaces. These problems can be solved by high-speed continuous parting heat treatment. Goal. The aim is development of a high-speed recrystallization annealing regime for increasing technological plasticity while maintaining the strength of cold-rolled sheet billets from deformable aluminum alloys. Methodology. The object of the study was thin-sheet (1 mm) billets from cold-rolled aluminum alloys AD1, AMts, AMg3. Strip blanks were subjected to high-speed continuous recrystallization annealing using contact heating. The metal was heated at a rate of 5 ºC/c to temperatures from 250 to 400 ºC with an interval of 50 ºC with a holding time of 5 - 15 min at the heating temperature and cooling in air. The quality of the annealing was judged by the nature of the obtained structure and indicators of mechanical properties. The ability to extract metal in different states was evaluated by the Eriksen method. Result. The least energy-consuming modes of continuous high-speed annealing of workpieces from the studied alloys were developed to obtain increased plasticity indicators (while maintaining strength) and improve cold pressure processing in the manufacture of products of complex configuration. Practical value. High-speed recrystallization annealing provides reduction of defects, saving of metal, improvement of productivity in the production of thin-sheet items by the method of cold deformation with deep and complex drawing.

Residual stress and deformation of thin titanium alloy plates joined by laser deposition

Residual stress and deformation of thin titanium alloy plates joined by laser deposition

Application of the Double Approximation Method for Constructing Stiffness Matrices of Volumetric Finite Elements

Introduction. When numerically solving problems of elasticity theory in a three-dimensional formulation by the finite element method, finite elements (FE) in the form of parallelepipeds, prisms and tetrahedra are used. Regularly, the construction of stiffness matrices of volumetric FE is based on the principle of isoparametricity, which involves the Lagrange polynomials to approximate the geometry and displacements. In computational practice, the most widespread FE are the so-called multilinear isoparametric FE with a linear law of approximation of displacements. The main disadvantage of these elements lies in the “locking” effect when modulating bending deformations. Moreover, the error of the numerical solution increases drastically in the case when the structure, in comparison to conventional deformations, undergoes significant displacements as a rigid whole. Long-term experience in solving problems of deformable solid mechanics by the finite element method has shown that existing volumetric FE have slow convergence, specifically, when modeling bending deformations of plates and shells. This study aims at constructing stiffness matrices of multilinear volumetric FE of increased accuracy allowing for rigid displacements based on the double approximation method.Materials and Methods. The mathematical apparatus of the double approximation method based on the principle of a separate representation of the distribution functions of displacements and deformations inside the element, was used to construct the stiffness matrices of volumetric FE. The storage and processing of the resulting system of equations was implemented in algorithmic terms of sparse matrices. Software development and computational experiments were carried out using the Microsoft Visual Studio 2013 64-bit computing platform and the Intel ® Parallel Studio XE 2019 compiler with the integrated Intel ® Visual Fortran Composer XE 2019 text editor. Visualization of the calculation results was performed using the descriptor graphics of the MATLAB computer mathematics package. A large eight-node SOLID185 CE of the ANSYS Mechanical software complex was used as a test sample.Results. Mathematical tool and software were developed to study the stress-strain state of massive structures under various types of external actions. The authorized application software package was verified on test examples with known analytical solutions. It has been shown that the constructed FE accurately satisfy the basic requirements for finite element modeling of spatial problems of elasticity theory.Discussion and Conclusion. The performed testing of the developed mathematical and program toolkit has shown that the finite elements constructed on the basis of the double approximation method can successfully compete with similar SOLID185 volumetric elements of the ANSYS Mechanical software complex. The proposed elements can be integrated into domestic import-substituting software systems that implement the finite element method in the form of the displacement method.

Hiemenz stagnation point flow of a second-order micropolar slip flow with heat transfer

Purpose This paper aims to study a non-Newtonian micropolar fluid flow over a bidirectional flexible surface for multiple exact solutions of momentum boundary layer and thermal transport phenomenon subject to wall mass flux, second-order slip and thermal jump conditions. Design/methodology/approach The coupled equations are transformed into ordinary differential equations using similarity variables. Analytical and numerical techniques are used to solve the coupled equations for single, dual or multiple solutions. Findings The results show that the stretching flow, shrinking flow, the wall drag, thermal profile and temperature gradient manifest large changes when treated for special effects of the standard parameters. The role of critical numbers is definitive in locating the domains for the existence of exact solutions. The nondimensional parameters, such as mass transfer parameter, bidirectional moving parameter, plate deformation strength parameter, velocity slips, material parameter, thermal jump and Prandtl number, are considered, and their physical effects are presented graphically. The presence of governing parameters exhibits special effects on the flow, microrotation and temperature distributions, and various exact solutions are obtained for the special parametric cases. Originality/value The originality and value of this work lie in its exploration of non-Newtonian micropolar fluid flow over a bidirectional flexible surface, highlighting the multiple exact solutions for momentum boundary layers and thermal transport under various physical conditions. The study provides insights into the effects of key parameters on flow and thermal behavior, contributing to the understanding of complex fluid dynamics.

Estrogen as a guardian of auditory health: Tsp1–CD47 axis regulation and noise-induced hearing loss

Objectives This study aimed to analyze the role of estrogen in noise-induced hearing loss (NIHL) and uncover underlying mechanisms. Methods An ovariectomized Sprague-Dawley rat model (OVX) was constructed to investigate the hearing threshold and auditory latency before and after noise exposure using the auditory brainstem response (ABR) test. The morphological changes were assessed using immunofluorescence, scanning electron microscopy and transmission electron microscopy. Proteomics and bioinformatics were used to analyze the mechanism. The findings were further verified through western blot and Luminex liquid suspension chip technology. Results After noise exposure, OVX rats exhibited substantially elevated hearing thresholds. A conspicuous delay in ABR wave I latency was observed, alongside increased loss of outer hair cells, severe collapse of stereocilia and pronounced deformation of the epidermal plate. Accordingly, OVX rats with estrogen supplementation exhibited tolerance to NIHL. Additionally, a remarkable upregulation of the thrombospondin 1 (Tsp1)–CD47 axis in OVX rats was discovered and verified. Conclusions OVX rats were more susceptible to NIHL, and the protective effect of estrogen was achieved through regulation of the Tsp1–CD47 axis. This study presents a novel mechanism through which estrogen regulates NIHL and offers a potential intervention strategy for the clinical treatment of NIHL.

Ballistic perforation of aramid laminates: Projectile nose shape sensitivity

The influence of projectile shape on the ballistic properties and mechanism of aramid laminates is investigated through experiments and simulations. Three types of projectiles (blunt, hemispherical, and ogival) are used to obtain ballistic curves. The dynamic penetration process, deformation and damage characteristics of the targets are analyzed. A three-dimensional finite element model is established, and good agreement is observed between the simulation and test results. The findings demonstrate that projectile shape significantly impacts the ballistic response of aramid laminates. As the projectile transitions from blunt and hemispherical to ogival, the ballistic limiting velocity decreases continuously, the area of target plate deformation and damage decreases, and the occurrence of delamination becomes less pronounced. And the energy dissipation through local damage, elastic deformation and overall motion of the aramid material is decreasing and the energy dissipation through friction is increasing.