Plate Modes Research Articles

Symmetric and asymmetric free vibrations of rotating eccentric annular plate

The symmetric and asymmetric free vibrations of rotating eccentric annular plate in uniform thermal environment are studied in present paper. The priority of research is clarifying the different combined effects of various factors on symmetric and asymmetric vibrations of eccentric annular plate. In order to conveniently obtain the natural frequency and vibration mode of eccentric annular plate with irregular physical domain, the transformed differential quadrature method is employed. Due to the rotational motion, the initial configuration caused by centrifugal force is calculated before vibration analyses. Then the traveling wave vibration arisen from the Coriolis force is investigated. By comparing the vibration characteristics of annular plate with/without eccentricity, the different impacts of interaction between the geometrical size, boundary conditions, temperature rise, rotational motion, and eccentricity on symmetric and asymmetric vibrations are discussed. Results show that eccentricity leads to the splitting phenomena only in asymmetric vibrations. And it does not affect the symmetry of vibration. Temperature rise results in that the fundamental vibration mode shape shifts from symmetric to asymmetric. However, eccentricity inhibits the change. Rotational motion causes the occurrence of traveling wave vibration in asymmetric vibration whereas not in symmetric vibration.

Performance study on a novel greenhouse cover structure with beam split and heat control function

Based on the principle of spacing prism, a novel greenhouse cover plate with beam split and heat control function is proposed. The visible light needed for plant growth transmits into the greenhouse and near-infrared radiation is absorbed to reduce the internal temperature. The target is to design a greenhouse cover plate that can not only reduces the temperature of greenhouse, but also reduces the energy consumption of greenhouses cooling system in summer. The relative position and size of the heat-absorbing plate are obtained through theoretical calculations. Based on the Monte Carlo light tracking principle, optical software is used to optimize the operating mode of the heat-absorbing plate. The relationship between air flow, efficiency and outlet temperature are analyzed by CFD numerical simulations. The integrating box is designed on principle of integrating ball, which is used to test this device's transmission and thermal characteristics. The test results are compared with double-layer vacuum glass under actual weather conditions. The results show that the transmission rate of spectral temperature control cover structure (STCCS) is about 60 % in the morning and afternoon, but it is lower at noon, approximately 47.32 %. Based on the thermal characteristic experiment results, it can be known that the average inside temperature of the STCCS box is decreased by 3.16 °C compared with the double-layer vacuum glass, and the thermal load is reduced by 21 %.

Low Profile Triangle-Shaped Piezoelectric Rotary Motor.

In this paper, we present research on a novel low-profile piezoelectric rotary motor with a triangle-shaped stator. The stator of the motor comprises three interconnected piezoelectric bimorph plates forming an equilateral triangle. Bimorph plates consist of a passive layer fabricated from stainless steel and four piezo ceramic plates glued to the upper and lower surfaces. Furthermore, spherical contacts are positioned on each bimorph plate at an offset from the plate's center. Vibrations from the stator are induced by a single sawtooth-type electric signal while the frequency of the excitation signal is close to the resonant frequency of the second out-of-plane bending mode of the bimorph plate. The offset of the spherical contacts allows for a half-elliptical motion trajectory. By contrast, the forward and backward motion velocities of the contacts differ due to the asymmetrical excitation signal. The inertial principle of the motor and the angular motion of the rotor were obtained. Numerical and experimental investigations showed that the motor operates at a frequency of 21.18 kHz and achieves a maximum angular speed of 118 RPM at a voltage of 200 Vp-p. Additionally, an output torque of 18.3 mN·mm was obtained under the same voltage. The ratio between motor torque and weight is 36 mN·mm/g, while the ratio of angular speed and weight is 28.09 RPM/g.

The use of a bamboo reinforced concrete foundation for a simple environmentally friendly house in Indonesia

In typical rural house construction, reinforced concrete foundation plates are not commonly used due to economic factors and the high cost of steel, which often results in compromised safety. Bamboo offers an affordable, renewable, CO2-absorbent material with high tensile strength. This research supported low-income communities by exploring the application of bamboo-reinforced concrete (PB) foundation plates. Technical feasibility, such as load capacity, crack pattern, and failure, were examined and compared with steel-reinforced concrete (PS) plates. Four foundation specimens with dimensions of 70 × 70 × 15 cm3 consisting of three PB foundation plates and one PS foundation were analyzed. The bamboo reinforcement had dimensions of 15 mm × 15 mm, and the steel reinforcement had a diameter of 10 mm. Different spacing variations were tested, including bamboo reinforcement spacings of 100 mm, 125 mm, and 150 mm, with a steel reinforcement spacing of 130 mm. During testing, a concentrated load was applied at the four corners of each foundation. The results showed that the PB foundation plate with a reinforcement spacing of 100 mm exhibited a 3.16% higher load capacity compared to PS foundation plate with a 10 mm reinforcement spaced at 130 mm. The stress zones, crack patterns, and failure modes of the PB foundation plates exhibited similarities to the PS foundation serving as the control. Based on these findings, PB foundation plates are a feasible option for a simple rural house foundation.

Study on energy conversion efficiency of wave generation in shake plate mode

In recent years, increasing attention has been paid to factors affecting the efficiency of converting wave energy from kinetic energy using shake plates. This research was based on the volume of fluid method to evaluate the energy conversion efficiency of waves generated in the shake plate mode. The effects of different shake plate parameters and water depths on the kinetic energy conversion efficiency were studied, and the results agreed well with experimental data. Results indicated that the angular velocity of the shake plate had the highest influence on kinetic energy conversion efficiency. In the range of ωx to 1.8ωx, the maximum kinetic energy conversion efficiency was 52.1 %. The influence of the oscillation amplitude of the shake plate on the kinetic energy conversion rate was relatively low. As a result, the kinetic energy conversion efficiency remained at approximately 18.10 % even with changes in oscillation amplitude. The kinetic energy conversion efficiency of the shake plate increased with an increase in water depth, with maximum increase 87.39 % seen between 0.15 and 0.2 m. Our research is expected to serve as a reference for the implementation of efficient wave energy generation systems worldwide.

NEW-GENERATION SUPERIOR SINGLE PLATING VERSUS LOW-PROFILE DUAL MINI-FRAGMENT PLATING OF DIAPHYSEAL CLAVICLE FRACTURES: A BIOMECHANICAL STUDY

Recently, a new generation of superior clavicle plates was developed featuring the variable-angle locking technology for enhanced screw positioning and optimized plate-to-bone fit design. On the other hand, mini-fragment plates used in dual plating mode have demonstrated promising clinical results. However, these two bone-implant constructs have not been investigated biomechanically in a human cadaveric model. Therefore, the aim of the current study was to compare the biomechanical competence of single superior plating using the new generation plate versus dual plating with low-profile mini-fragment plates.Sixteen paired human cadaveric clavicles were assigned pairwise to two groups for instrumentation with either a 2.7 mm Variable Angle Locking Compression Plate placed superiorly (Group 1), or with one 2.5 mm anterior plate combined with one 2.0 mm superior matrix mandible plate (Group 2). An unstable clavicle shaft fracture AO/OTA15.2C was simulated by means of a 5 mm osteotomy gap. All specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with bidirectional torsion around the shaft axis and monitored via motion tracking.Initial stiffness was significantly higher in Group 2 (9.28±4.40 N/mm) compared to Group 1 (3.68±1.08 N/mm), p=0.003. The amplitudes of interfragmentary motions in terms of craniocaudal and shear displacement, fracture gap opening and torsion were significantly bigger over the course of 12500 cycles in Group 1 compared to Group 2; p≤0.038. Cycles to 2 mm shear displacement were significantly lower in Group 1 (22792±4346) compared to Group 2 (27437±1877), p=0.047.From a biomechanical perspective, low-profile 2.5/2.0 dual plates demonstrated significantly higher initial stiffness, less interfragmentary movements, and higher resistance to failure compared to 2.7 single superior variable-angle locking plates and can therefore be considered as a useful alternative for diaphyseal clavicle fracture fixation especially in unstable fracture configurations.

Effect of Lode angle in predicting the behaviour of stiffened 921A steel target plates in ballistic impact by truncated ogive projectiles

Two sets of penetration experiments with truncated ogive projectiles were carried out on large unstiffened and stiffened target plates made of 921A steel; the residual velocity of the projectile was recorded, and the failure mode of the target was analysed. The experimental results show that the unstiffened target plate exhibited obvious petaling failure, whereas the stiffened plate exhibited a coupled complex failure mode because of its spatial structure. Many recent studies have shown that the failure strain of metals can be affected by the Lode angle in addition to the stress triaxiality, so this study introduced the Lode angle into the fracture criterion to investigate whether it affects the ballistic behaviour of the target plate. A numerical model was established in the Ansys LS-DYNA finite-element software, with the mechanical properties of 921A steel characterized by the Johnson–Cook (JC) constitutive equation and the failure strain controlled by either the JC fracture criterion independent of the Lode angle or the modified Mohr–Coulomb (MMC) fracture criterion dependent on the Lode angle. The numerical and experimental results shows that both fracture criteria predict well the residual velocity after penetration. However, the failure mode of the target plate obtained with the JC fracture criterion exhibits a reaming process, as reflected in the local upward dish deformation, and although the target plate also forms multiple petals, they are all connected and gathered inward, acting as a whole. The results calculated with the MMC fracture criterion predict the experimental ones well, with the unstiffened plate exhibiting obvious petaling failure. Finally, the MMC fracture criterion is added to the numerical model of the stiffened plate, and the calculation results show that the ballistic impact behaviour of the target plate can still be predicted effectively.

Electrodeposited Sn-Cu-Ni alloys as lead-free solders on copper substrate using deep eutectic solvents: The influence of electrodeposition mode on the morphology, composition and corrosion behaviour

In this work we present the pulsed current (PC) electrodeposition of Sn-Cu-Ni alloy as lead-free solder candidate, from choline chloride – ethylene glycol eutectic mixtures (1:2 molar ratio) onto copper metallic substrates. Electrolytes containing Sn2+, Cu2+ and Ni2+ salts in the selected deep eutectic solvent have been considered. The effect of the applied frequency of PC on the morphology, composition and melting point of the alloy is discussed and compared to the ones obtained using direct current (DC) plating mode. A refinement of the grain size and lower melting temperature of the alloy were noticed when pulsed current was applied.A comparative analysis of the electrochemical corrosion behaviour at macro- and micro- scale has been performed in 0.5 M and 0.1 M NaCl solutions involving potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode (SVET) techniques. Furthermore, an analysis after 96 h of exposure to salt mist test simulating a corrosive attack in harsh environment is presented, too. The obtained results showed enhanced corrosion resistance of the ternary alloys electrodeposited under PC conditions (the best for 1.67 Hz frequency) as compared to those using DC. Additionally, Raman spectroscopy evidenced the presence of tin oxi/hydroxy chloride and tin oxides as surface corrosion products. A corrosion mechanism has been proposed.

Analytical study on the dynamic mechanical behaviours of foam-core sandwich plate under repeated impacts

The foam-core sandwich structures are probably subjected to repeated impact loadings in engineering applications, resulting in structural plastic deformation and accumulative damage. A valuable analytical approach is needed to predict the accumulative plastic deformation of foam-core sandwich structures under repeated impacts. In this paper, an analytical model of the dynamic responses of foam-core sandwich plates under repeated impacts is proposed using the circumscribing yield locus and the inscribing yield locus based on the rigid-perfectly plastic theory. By employing the principle of energy dissipation rate balance, the analytical expressions of structure permanent deformation and peak force are obtained from the iteration of initial conditions. In addition, polyvinyl chloride (PVC) foam has steady chemical properties and corrosion resistance, which can better adapt to the practical environment and meet the needs of structural protection. To validate the proposed analytical model, the repeated impact dynamic mechanical behaviours of PVC foam-core sandwich plates were experimentally and numerically studied. Results show that theoretical results such as the permanent deformation, peak force, and deformation modes of foam-core sandwich plates under repeated impacts are in good agreement with experimental and numerical results. With the increase in impact numbers, the global bending deformation and local indentation deformation of facesheets increase, the PVC foam core layer is constantly being compressed, and the bottom facesheet plays an increasingly important part in the repeated impact energy absorption with a maximum value of 29.20 %.

Research on low-frequency bender disk transducer driven by multiple relaxor ferroelectric single crystal disks

In this paper, we investigate the low-frequency bender disk transducer designed by the relaxor ferroelectric single crystal. First, we introduce the principle of the bender disk transducer, and use multiple single crystal disks as driving materials to excite the bending vibration mode of the metal plate, which reduces the operating frequency of the transducer. Then we establish the three-dimensional finite element model of the bender disk transducer driven by multiple single crystal disks, analyze the influence of the number and position distribution of single crystal disks on the transducer performance, and compare with that of the piezoelectric ceramic transducer with the same structure. Finally, we manufacture the proposed relaxor ferroelectric single crystal, piezoelectric ceramic transducers and the conventional piezoelectric ceramic bender disk transducer respectively, and carry out the experimental measurement in an anechoic water tank. The experimental results show that for the proposed single crystal transducer, its measured maximum transmitting voltage response (TVR) is 126.2 dB at 1.1 kHz, which is 13.4 dB higher than that of the proposed piezoelectric ceramic transducer, and its frequency corresponding to the maximum TVR is reduced by 700 Hz compared with the conventional piezoelectric ceramic bender disk transducer.

Vibration of microperforated plate with spatial distribution of multiple-sized perforations

Recent works by the authors on homogeneous MPPs have highlighted the structural damping capabilities of MPPs in the low frequency range. The developed theoretical approach was based on the analogy between an MPP and a porous plate. The added damping is due to visco-thermic effects coupled to fluid-structure interactions. The added damping maxes out at a characteristic frequency depending on perforation diameter. In order to reduce plate vibrations, it was advised to match the characteristic frequency to a plate mode. It is proposed here to maximize the added damping effect on several vibration modes by focusing on MPPs with multiple-sized perforations and with spatial distribution of perforations. As an extension of the previous analytical model, an approach based on the electro-acoustic analogy is established to capture the effect of multiple-sized perforations. Moreover, a perforation ratio gradient is included in the approach to model an MPP with inhomogeneous spatial distribution of perforations. Experimental measurements on MPPs validate the proposed analytical model. Results show that: (i) MPP with multiple-sized perforations increases the frequency band of the effective damping; (ii) the added damping increases when the perforations are distributed around the antinodes of the considered mode, (iii) the two effects can be combined.

Analyzing vibration modes in non-homogeneous parallelogram plates

This study analyzes vibration modes in non-homogeneous orthotropic parallelogram plate with a one-dimensional circular thickness, focusing on SCCC edge condition, where C and S represent the clamped and simply supported edges of the plate, respectively. Circular Poisson’s ratio variation is considered, along with linear temperature changes. The study demonstrates the advantages of variable Poisson’s ratio over density parameter variation in obtaining shorter vibration time periods. Orthotropic parallelogram plate, thermal gradient, circular tapering, nonhomogeneity.

Direct numerical simulation-based vibroacoustic response of plates excited by turbulent wall-pressure fluctuations

We use direct numerical simulation to study the vibroacoustic response of an elastic plate in a turbulent channel at $Re_\tau$ of 180 and 400 for three plate boundary conditions and two materials – synthetic rubber and stainless steel. The fluid–structure–acoustic coupling is assumed to be one-way coupled, i.e. the fluid affects the solid and not vice versa, and the solid affects the acoustic medium and not vice versa. The wall pressure consists of intermittent large-amplitude fluctuations associated with the near-wall, burst-sweep cycle of events. For stainless steel plates, displacement has similar large-amplitude peak events due to comparable time scales of plate vibration and near-wall eddies. For synthetic rubber plates, large-amplitude displacement fluctuations are observed only near clamped or simply supported boundaries. Away from boundaries, plate displacement resembles an amplitude-modulated wave, and no large-amplitude events are observed. We discuss displacement and acoustic pressure spectra over different frequency ranges. For frequencies much smaller than the first natural frequency, the product of plate-averaged displacement spectrum and bending stiffness squared collapses with Reynolds number and plate material in outer units. At high frequencies, displacement and acoustic pressure spectra scale better in inner units, and the scaling depends on the type of damping. For synthetic rubber plates, the spectra display an overlap region that collapses in both outer and inner units. Soft plate deformation displays a range of length scales. However, stiff plate deformation does not exhibit a similar range of scales and resembles plate mode shapes. The soft plate has two distinct deformation structures. Low-speed, large deformation structures with slow formation/break-up time scales are found away from boundaries. High-speed, small deformation structures with fast formation/break-up time scales formed due to boundary reflections exist near the boundaries.

Mindlin cracked plates modelling and implementation in train-track coupled dynamics

Nowadays, the widely constructed ballastless track in high-speed railways will inevitably suffer from localized damage cracks induced by complicate environmental effects, which would change its designed dynamic performance under train dynamic loads and further affect its service life and durability. To this end, a semi-analytical approach of the in-plane and the out of plane forced vibration for Mindlin plates with a side crack are derived, and is further implemented into the train-track coupled dynamic (TTCD) system which comprehensively considering nonlinear wheel-rail contact and 3D spatial flexibility of the cracked track slab. The dynamic partial differential equation of the cracked slab is derived by Hamilton principle and discretized by Galerkin method. Then the eigenvalues and forced vibrations of the cracked slabs for both in-plane and flexural vibrations are tackled utilizing a set of powerful trigonometric modified by special corner function, which can effectively explain the singularity of stress at the crack tip and the discontinuity of deformation on both sides of the crack. The eigenvalue analysis and mode shapes of the cracked plate mode in free boundary condition are compared with the finite element method to verify its accuracy. Meanwhile, the reliability of the proposed dynamics model is verified by comparing with the responses predicted by the co-simulation technology. Finally, the discrepancies of dynamic responses of the track slab with or without a side crack are analyzed, and the effects of various operation speeds and support stiffness on the dynamic behaviour of both slabs are revealed. Results indicates that the track slab with a side crack has significant distinctions on the slab dynamic signals in both time and frequency domains, and the amplitude amplification phenomenon occurs in some specific areas compared with the intact slab; The type-Ⅱ stress intensity factor (SIF) is more sensitive to train speeds, while the support stiffness is highly correlated to all types of SIFs. This work may contribute to the scientific maintenance and health monitoring of high-speed railway tracks.

Stress intensity factors analysis for crack around film cooling holes in Ni-based single crystal with contour integral method

PurposeThis paper aims to provide SIF calculation method for engineering application.Design/methodology/approachIn this paper, the stress intensity factors (SIFs) calculation method is applied to the anisotropic Ni-based single crystal film cooling holes (FCHs) structure.FindingsBased on contour integral, the anisotropic SIFs analysis finite element method (FEM) in Ni-based single crystal is proposed. The applicability and mesh independence of the method is assessed by comparing the calculated SIFs using mode of plate with an edge crack. Anisotropic SIFs can be calculated with excellent accuracy using the finite element contour integral approach. Then, the effect of crystal orientation and FCHs interference on the anisotropic SIFs is clarified. The SIFs of FCH edge crack in the [011] orientated Ni-based single crystal increases faster than the other two orientations. And the SIF of horizontal interference FCHs edge crack is also larger than that of the inclined interference one.Originality/valueThe SIFs of the FCH edge crack in the turbine air-cooled blade are innovatively computed using the sub-model method. Both the Mode I and II SIFs of FCHs edge crack in blade increase with crack growing.

Levy-type analytical series solution for the three-dimensional free vibrations of functionally graded material rectangular plates with piezoelectric layers

Analytical solutions founded on three-dimensional theories play a crucial role in evaluating the credibility and precision of different plate theories and numerical methodologies. While Levy-type analytical solutions are widely recognized, they have been primarily confined to purely elastic plates. This study introduces a Levy-type analytical series solution for three-dimensional vibrations in a sandwich rectangular plate featuring a functionally graded material (FGM) core, along with piezoelectric material (PM) layers on the top and bottom surfaces. The behaviors of the FGM and PM layers were described using three-dimensional elasticity and piezoelasticity theories, respectively. In this study, the displacement functions and electric potential of each layer were expanded by Fourier series and polynomial auxiliary functions. An analytical series solution was then established by satisfying the governing equations of each layer, the mechanical and electric boundary conditions on the six faces of the plate, and the continuity conditions on the interfaces between the PM and FGM layers. To validate the proposed solutions, in-depth convergence studies were conducted for the vibration frequencies of the first six modes of sandwich square plates with various boundary conditions on the other pair of side faces. The well-converged results were then compared with published data based on various plate theories to verify the accuracy of these published data. Finally, accurate nondimensional frequencies were tabulated for the first six modes of sandwich rectangular plates with various aspect ratios, thickness-to-width ratios, PM-to-FGM layer thickness ratios, power law indices for the FGM layer, and six combinations of boundary conditions. These new numerical results when piezoelectric coupling is considered should be very useful to future analytical and numerical studies.

Experimental and analytical investigation on forced and free vibration of sandwich structures with reinforced composite faces in an acidic environment

The main objective of this study is to investigate the impact of nanoparticles as reinforcement material on the vibrational behavior of sandwich structures in an acidic medium. The glass fiber reinforced polymer (GFRP) faces were fabricated with and without the addition of 3 wt% nanoclay and nanosilica to determine the mechanical behaviors of the GFRP faces in the presence of an acidic medium. The obtained results showed adding 3 wt% of nanoclay caused better durability and less mass variation of composite specimens in sulfuric acid. The “Coefficient of acidic immersion expansion” (βacid) is determined by measuring the length and mass variation of GFRP specimens in the immersion, and applied to low order piecewise shear deformation theory (LOPSDT) for the first time; Also the frequency results of LOPSDT have been shown good agreement in validation with the ANSYS numerical solution. It is shown that acidic environment reduces the frequency of the first mode of sandwich plates with reinforced face by 3 wt% nanosilica, and nanoclay has increased by 6.81 % and 4.66 %, respectively. This study indicates after one month of immersion, the natural frequency of the sandwich with pure, and 3 wt% nanoclay reduces about 1 %, and the natural frequency of the sandwich with the faces reinforced with 3 wt% nanosilica reduces by more than 3 %; Moreover, the frequency of forced vibrations, caused by acidic immersion expansion, was improved significantly by 10.04 % and 6.54 % in the first mode by incorporating 3 wt% of nanoclay, and nanosilica into the faces of the sandwich in one month of immersion compared to the sandwich with pure faces.

Validation of zero-group-velocity feature guided waves in a welded joint

Extensive research has been conducted on zero-group-velocity (ZGV) Lamb waves in elastic plates, demonstrating significant progress in the field of nondestructive testing. However, there is a scarcity of studies focusing on ZGV modes in complex structures. In this paper, we present our research investigating the presence of ZGV feature guided waves (FGWs) in a welded joint. Our approach follows a similar methodology used to study ZGV Lamb waves in elastic plates. By employing two-dimensional (2D) finite element (FE) modeling, we analyze the response spectra of the welded joint when subjected to a force source, revealing the occurrence of resonance in the response spectra. To investigate resonance modes in the welded joint, we employ the three-dimensional (3D) time-step FE method. By applying spatial 2D and short-time Fourier transforms to the received time-domain signals, we analyze the frequency content and spatial distribution of the signals. This analysis allows us to verify the existence of non-propagation and propagation modes in the welded joint. The non-propagation mode refers to the presence of signals with a zero wavenumber, indicating that they do not propagate or travel along the welded joint. These signals are typically associated with local resonances or vibrations within the welded joint itself. On the other hand, the propagation mode corresponds to signals with nonzero wavenumbers, suggesting that they propagate or travel along the welded joint. Furthermore, by further analyzing the propagation mode in the welded joint, similar to the analysis of ZGV modes in solid plates, we have observed that it also exhibits ZGV characteristics based on the wavenumber-frequency spectra. To further analyze acoustic field distributions at resonance frequencies, we utilize the semi-analytical finite element method in conjunction with the perfectly matched layer method. The results obtained from this analysis are consistent with those obtained from the 2D FE method and 3D time-step FE method, thereby confirming that propagation modes with ZGV characteristics at resonance frequencies correspond to FGWs, which we refer to as ZGV-FGWs. Through this step-by-step analysis, we ultimately establish the existence of ZGV-FGWs in the welded joint. This study introduces fresh ideas and serves as a point of reference for future research on ZGV-FGWs in complex structures.

Study on the deformation of inter-rib shell plate of reinforced conical shell structure under deep-water-explosion loading

The reinforced cylindrical and conical column structures are widely used structural forms in underwater vehicle structures. In this paper, the reinforced conical shell structure in the transition compartment of underwater vehicles was used as the research object. Based on the shock wave propagation theory and ABAQUS acoustic structure coupling numerical simulation method, the numerical simulation model of conical shell structure under deep-water explosion load was established.The deep-water explosion simulation of conical shell structure under the conditions of different water depths, charges and explosion distances was carried out, and the deformation and failure mode of small depressions in the shell plate between ribs of stiffened conical shell structure was obtained, that was, independent small pits were formed along the axis direction. According to the theory of elastic-plastic deformation of plate and shell structure, the small pits of shell and plate between ribs were approximated as the deformation of trapezoidal plate, and the deformation function of trapezoidal plate was obtained by coordinate transformation. The deformation energy of plate and shell was divided into bending deformation energy and midplane strain energy. By establishing the correlation between explosion energy and deformation energy, the theoretical calculation model of the small pit deformation mode of shell and plate between ribs was obtained.

New generation of superior single plating vs. low-profile dual minifragment plating in diaphyseal clavicle fractures: a biomechanical comparative study

Recently, a new generation of superior clavicle plates was developed featuring the variable angle locking technology for enhanced screw positioning and a less prominent and optimized plate-to-bone fit design. On the other hand, mini-fragment plates in dual plating mode have demonstrated promising clinical results. The aim of the current study was to compare the biomechanical competence of single superior plating using the new generation plate versus dual plating using low-profile mini-fragment plates. Sixteen paired human cadaveric clavicles were pairwise assigned to two groups for instrumentation with either a superior 2.7 mm Variable Angle Locking Compression Plate (Group 1), or with one 2.5 mm anterior combined with one 2.0 mm superior matrix mandible plate (Group 2). An unstable clavicle shaft fracture (AO/OTA 15.2C) was simulated by means of a 5mm osteotomy gap. Specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with bidirectional torsion around the shaft axis and monitored via motion tracking. Initial construct stiffness was significantly higher in Group 2 (9.28 ± 4.40 N/mm) compared to Group 1 (3.68 ± 1.08 N/mm), p=0.003. The amplitudes of interfragmentary motions in terms of axial and shear displacement, fracture gap opening and torsion, over the course of 12,500 cycles were significantly higher in Group 1 compared to Group 2, p≤0.038. Cycles to 2mm shear displacement were significantly lower in Group 1 (22792 ± 4346) compared to Group 2 (27437 ± 1877), p=0.047. From a biomechanical perspective, low-profile 2.5/2.0 dual plates can be considered as a useful alternative for diaphyseal clavicle fracture fixation especially in less common unstable fracture configurations. 2.7 single superior variable angle locking plates and can therefore be considered as a useful alternative for diaphyseal clavicle fracture fixation especially in less common unstable fracture configurations.