Damage In Plates Research Articles

In Situ Hydrogel Polymerization to Form a Flexible Polysaccharide Synergetic Binder Network for Stabilizing SiOx/C Anodes.

Today, the commercial application of silicon oxides (SiOx, 1 < x < 2) in lithium-ion batteries (LIBs) still faces the challenge of rapid performance degradation. In this work, by integrating hydrothermal and physicomechanical processes, water-soluble locust bean gum (LBG) and xanthan gum (XG) are utilized to in situ form an LBG@XG binder network to improve the performance of SiOx/C anodes. As a synergy of LBG and XG polysaccharides in hydrogel polymerization, LBG@XG can tightly wrap around SiOx/C particles to prevent plate damage. The flexible SiOx/C anode with the LBG@XG binder exhibits capacity retentions of 74.1% and 76.4% after 1000 cycles at 0.5 A g-1 and 1 A g-1, respectively. The full battery capacity remains stable for 100 cycles at 1 C and the rate performance is excellent (103 mAh g-1 at 3 C). This LBG@XG is demonstrated to be highly electronegative and has a strong attraction to SiOx/C particles, thereby reducing the expansion and increasing the stability of the SiOx/C anodes when coupled with the flexible binder network. In addition to the promising LBG@XG binder, this work also provides a research idea for developing green water-based binders suitable for application in the SiOx/C anodes of LIBs.

Discussion on Fatigue Reliability Evaluation Method of Welded Structure of Carbody Based on Digital Twin

Abstract Taking the key welds of the heavy-duty gondola carbody as the research object, first, the fatigue assessment of the carbody is carried out based on the quasi-static the main S–N curve method, and the quasi-static evaluation method is discussed; second, the typical welds are selected. Based on the full-size bench physical test and virtual test of railway freight carbody, the quasi-static method is discussed; finally, the line test is used to verify the results. The results show that: (1) among all the load conditions in the quasi-static analysis of railway freight cars, the damage of the core plate needs to be considered according to different parts of the carbody, and this condition is effective for the evaluation of the bearing area of the linear load transfer of the carbody for the welds with nonlinear load transfer such as floor, the stress response caused by core plate load has the problem of over-estimation of damage. (2) The lap weld of floor and beam is less damaged under heavy load, but the stress response is larger in empty state, which indicates that the vibration effect should be considered in the design. (3) The virtual test can make up for the problem of traditional quasi-static analysis. The combination of the two can better realize the fatigue reliability evaluation of carbody.

Damage detection and localization based on different types of actuators using the electromechanical impedance method in 3D-printed material

Electromechanical impedance (EMI) measurement, using piezoelectric transducers (PZTs) in the high-frequency range is a potential method for assessing the health of lightweight structures. The major objective of this work is to comprehend how different actuators react to damage in additively manufactured (AM) polymer structures. A novel frequency-range selection technique was suggested based on the maxima of the standard deviation of the impedance frequency spectra gathered for the referential and damage cases. A 3D-printed acrylonitrile butadiene styrene (ABS) plate was used for the investigation, where two PZT and one macro fiber composite (MFC) actuator were glued to the surface. Small magnets were used to simulate damage and were positioned at increasing distances from each transducer as EMI measurements were made using the MFC and 1 PZT. This served both in studying the transducers’ sensitivity to damage and selecting the proper frequency range for damage detection utilizing the standard-deviation approach. The EMI-acquired data from the MFC actuator displays damage-sensitive peaks in a low-frequency band (0–58 ), while the PZT shows a good sensitivity in a higher frequency range (94–304 ). In order to evaluate the PZT and MFC actuators’ sensitivity to damage in the 3D-printed ABS plate, impact damage is also generated in the plate’s center. The impedance-based damage indices obtained from different types of PZTs (2 PZTs and 1 MFC) were projected to the same base level and then fused—for the first time—for impact-damage localization and further added magnetic mass damage localization. The obtained damage index values of impedance are encouraging for the evaluation of AM polymer structures with a 4.48 mm positional error from a real location by fusing data in the different frequency ranges for PZTs and MFC. The damage localization error increases significantly to the new location beyond the damage sensitivity range of the PZT2 and MFC for the added magnetic mass on the 3D printed structure.

Combination of wavelet transform and extreme learning machine for detecting damages in composite plates

This paper reports a two-stage damage detection method for effectively identifying multi-damage in composite plate structures. The first stage focuses on detecting damage locations using the wavelet transform to reveal the singularities from a modal shape of the composite plate. In the second stage, extreme learning machine (ELM) is employed to search the damage severities from the pre-calculated damage evaluation database (the relationship between the natural frequencies and severities). Using finite element method (FEM) and experimental modal analysis (EMA), the numerical simulations and experimental investigations are executed to verify the effectiveness of the combination method for simply supported composite plates structures with various damages. Results show that the proposed two-stage method is effectively to identify multiple damages in composite plate structures with reasonable precision might be extend to real-world applications.

A new diagnostic system for damage monitoring of BFRP plates

This work studies a new framework for damage detection in composite plate systems made of Basalt Fiber Reinforced Polymer (BFRP) through analysis of electrical capacitance sensors (ECS) measurements. First, the plate damage finite element model is established, where one side of the plate is subjected to the fatigue effect of applied pressure, then the electrical potential difference between the electrode pairs (EPD) is measured before and after damage. The distributed ECS measuring electrodes are installed around the Plate and loaded the transient external excitations between each other. The transfer function (TF) of the “open loop” plate system is suggested and applied to reflect damage evolution. The accuracy and reliability of the proposed technique are validated with available experimental results in the literature. Results show that the signal magnitude will suddenly and sensitively change when the damage starts to grow under electrode pairs, which shows the effectiveness of the proposed approach and promising potential for engineering applications.

Detection of Internal Damage in CFRP-Laminated Plates Using Signal Extraction Method

Detection of Internal Damage in CFRP-Laminated Plates Using Signal Extraction Method

Damage Mechanism of Copper Cooling Plate on Large Blast Furnace

This work investigates the application of cooling plate in a 4500 m3 blast furnace in China. Scanning electron microscopy–energy dispersive X‐ray spectroscopy and an optical microscope are used to examine the affected area. The results demonstrate that using a cooling plate in a huge blast furnace has a positive effect, notably in furnace belly and bosh, where the damage rate is less than 3%. While the cooling plates in the middle shaft are more severely damaged, with a damage rate of up to 55.40%. The majority of the copper cooling plate's damage is centered in the water channel area, where there are furrows and numerous microcracks on the damaged surface, as well as a tiny quantity of metallurgical slag attached. Cracks form on both the inside and outside of the water channel, and the grains surrounding the cracks rise significantly, which is the primary cause of the cooling plate's water leaking. The main factor of cooling plate damage in the early stage is wear, and the cracking caused by force in the later stage. The use of a copper cooling plate from the furnace bosh to the lower shaft is preferable to the use of a copper cooling stave.

Detection of barely visible impact damage in composite plates using non-linear pump-probe technique

In the last decades, composite materials have been increasingly used in aircraft structures as a mean to reduce the weight. For safety reasons, periodic checks of impact-induced damage need to be performed. In that framework, ultrasound non destructive testing has proven its ability to detect macro-defects such as delamination. However, at early stages, Barely Visible Impact Damage (BVID) may not be detected via linear ultrasound techniques. In recent years, non-linear ultrasound has gained traction for the inspection of such defects. However, detection of the weak non-linear defect signature buried in ambient noise remains challenging, and depends on an empirical choice of excitation frequencies. This study focuses on the evaluation of a non-linear pump probe ultrasound inspection technique applied to BVID in multilayer carbon fibre reinforced composites used in aeronautics. In particular, the influence of various experimental parameters on the measured non-linear response is studied. A low frequency pump wave (via a shaker) and a high frequency wave (via a piezoelectric transducer) are transmitted to the medium while a second transducer records the ultrasonic response. Both pump and probe waves are sent in the form of a few secondslong frequency sweep, in the audible and ultrasonic range respectively. Appropriate post processing is then applied to the recorded signals to retrieve the non-linear response of the defect. The procedure is repeated on several composite plates with and without impact damages. The nonlinear response appears in the form of modulation sidebands in the frequency spectrum of the post-processed signals. The relative amplitudes of the side bands obtained for the various samples with various defect sizes and excitation amplitude or frequency content are studied. Optimal experimental parameters were obtained and led to a good detection of defects. The limits of the method are also discussed.

Corrosion Detection and Surface Repair with Coatings on Condensate Storage Tanks Internal Surfaces

In the Nuclear power plant Krško, there are two single hull condensate storage tanks with floating diaphragm each containing up to 757 m3 of demineralized water. The main purpose of these two storage tanks is to provide a capacity of cooling water for cooling the reactor coolant system via steam generators with the use of auxiliary feedwater pumps. This is a very important function from the safety point of view and that is the reason that both storage tanks are listed as safety class 3 components. It is also possible to fill up the condensate system if other means are not available. Condensate storage tanks are subject to periodic testing and periodic inspections to determine the condition of the components. Both tanks are in operation since the start-up of the powerplant, are located outside, and are exposed to different degradation processes. There was a concern that the tanks are leaking because there were often small puddles of water near the tanks. There were no changes in the levels of tanks. The design of tanks is a single hull, so there is no indication if a small leak is present.In the outage 2018, both tanks were emptied and examined with NDE methods to find any corrosion damage of bottom plates and any untight spots on adjacent welds.The article is about the NDE methods that were used (Magnetic Flux Leakage, Ultrasonic and Vacuum Box inspection) to determine the condition of the floor plates and adjacent welds as well as the process of internal surface reparation with coatings. Process of coatings qualification for use in safety class components is also explained: dedication process for material up-grade from non-safety related to safety-related because CY tank linings are classified as safety-related according to RG 1.54, rev 2 and corresponding ASTM standards and NEK technical specification SP-A5001. All activities for surface repair with coatings shall comply with safety-related requirements. Also, extensive immersion tests with selected and specially defined parameters were performed in NEK chemical laboratory in order to select the most suitable coating system for surface repair of CY tank floor lining. Further details concerning immersion tests are presented below.

T-2 toxin-induced chondrocyte apoptosis contributes to growth plate damage through Smad2 and Smad3 signaling

The growth plate cartilage is one of the most common areas that Kashin-Beck Disease attacks. However, the exact mechanism of growth plate damage remains unclear. Here, we demonstrated that Smad2 and Smad3 were closely associated with the differentiation of chondrocytes. Reduction of Smad2 and Smad3 were found both in T-2 toxin-induced human chondrocytes in vitro and in T-2 toxin-induced rat growth plate in vivo. Blunting Smad2 or Smad3 both strikingly induced human chondrocytes apoptosis, implying a plausible signaling pathway to clarify the mechanism of T-2 toxin-induced oxidative damage. Furthermore, decreased Smad2 and Smad3 were also observed in the growth plates of KBD children. Collectively, our findings clearly illustrated that T-2 toxin-induced chondrocyte apoptosis contributes to growth plate damage through Smad2 and Smad3 signaling, which refines the pathogenesis of endemic osteoarthritis and provides two potential targets for the prevention and repairment of endemic osteoarthritis.

Intervertebral disc degeneration and vertebral end plate damage in acute lumbar disc herniation

Abstract Background: Although microtrauma, gene polymorphisms, or subclinical infection could initiate lumbar disc herniation (LDH), the final pathway culminating in herniation can involve two possible trajectories—degeneration of nucleus pulposus or vertebral end plate (EP) damage. We performed a retrospective case–control study to understand the relative role played by disc degeneration (DD) and EP changes in acute LDH. Materials and Methods: MRI of 300 consecutive patients with acute LDH (&lt;6 weeks) was evaluated for the type of LDH, severity of DD by Pfirrmann’s grading, and EP Modic changes (MC) for its type, distribution, and location in EPs. Among the1500 discs evaluated in 300 patients, 308 had disc herniation (cases) and 1192 acted as controls. Results: 98.8% of LDH had grade ≥3 DD (P &lt; 0.001). The mean DD was higher in herniated discs (P &lt; 0.05). From a mean 1.98 in normal discs, it increased to 3.31 in disc bulges, 3.73 in disc protrusions/extrusions, and 3.83 in sequestrations. Herniated discs had more MCs than normal discs (38.3%, 118/308) (P &lt; 0.001). Although in normal discs, only 7.7% had MC, herniated disc subtypes showed a progressive increase in the incidence of MC (26.2% in disc bulges, 37.5% in disc protrusion/extrusions, and 58.3% in sequestrations). MC on both EP was strongly associated with LDH (odds ratio = 9.76). Posterior corner MC had a significant association with LDH (72.72%, P &lt; 0.001). Conclusion: DD seems to be a common thread in all patients (98.8%) with LDH, whereas EP damage seems to be specific pathway in a subset (38.3%). The study showed a significant degeneration of nucleus pulposus in most (98.8%) herniated discs. Compared with nonherniated discs, vertebral MC had a higher incidence in herniated discs (38%), and interestingly these were of subacute fatty type 2.

Failure Mechanism of Tensile CFRP Composite Plates with Variable Hole Diameter

Real thin-walled composite structures such as aircraft or automotive structures are exposed to the development of various types of damage during operation. The effect of circular hole size on the strength of a thin-walled plate made of carbon fibre-reinforced polymer (CFRP) was investigated in this study. The test object was subjected to tensile testing to investigate the strength and cracking mechanism of the composite structure with variable diameter of the central hole. The study was performed using two independent test methods: experimental and numerical. With increasing diameter of the central hole, significant weakening of the composite plate was observed. The study showed qualitative and quantitative agreement between the experimental and numerical results. The results confirmed the agreement of the proposed FEM model with the experimental test. The novelty of this study is the use of the popular XFEM technique to describe the influence of the hole size on the cracking and failure of the composite structure. In addition, the study proposes a new method for determining the experimental and numerical damage and failure loads of a composite plate under tension.

Numerical Modeling of Low-Velocity Impact on Composite Laminates

The response over the low-velocity impact of various shape impactors on a glass fiber reinforced polymer composite has been numerically analyzed with a hemispherical, flat, partially flat and truncated shaped impactor used to analyze the behavior of resistance of a GFRP composite at various speeds. The numerical analysis was carried out using finite element analysis software, ABAQUS (Dynamic/Explicit). To assess the response of the composite laminates while impacting, finite element models were developed. The Hashin failure criteria were used to represent braided glass-fiber reinforced composite plate damage. Regarding projectile shape, the impact reaction of the composite was examined. The results also show that the mechanical response of woven glass fiber polymer composite under low-velocity projectile impact largely depends on the impactor’s nose shape and the velocity of the impactor.

Influence of sewage culvert cover plate thickness on dynamic response and damage of the cover plate under gas explosion

In order to address the risk of combustible gas explosions in sewage culverts, a numerical model was established using ANSYS/LS-DYNA software. The model consisted of a culvert and a cover plate, and was used to study the effect of cover plate thickness (ranging from 0.08 m to 0.12 m) on the dynamic response and damage of the structure under explosive loads. The results indicated that, during the loading negative pressure stage, the equivalent stress peak value of the central monitoring unit of the cover plate first increased and then decreased with increasing cover plate thickness. Additionally, the maximum principal stress peak value first decreased and then increased, while the maximum shear stress peak value first increased and then decreased. During the loading positive pressure stage, the maximum principal strain peak value of the monitoring unit decreased overall with increasing cover plate thickness. However, the equivalent plastic strain peak value initially increased and then decreased gradually. The equivalent strain indicated that plastic damage occurred in the cover plate. Beyond a thickness of 0.11 m, increasing the cover thickness did not appear to enhance its resistance to plastic damage. The damage analysis revealed that as cover plate thickness increased, the peak displacement and velocity of the monitoring unit continued to decrease, while the overall stability and explosive resistance of the cover plate increased. Additionally, the number of damaged fragments decreased. However, once the cover plate thickness reached 0.11 m, the bonding performance of the reinforced concrete structure had been fully developed, increasing the thickness of the cover plate no longer had a significant impact on the explosive resistance of the cover plate.

Dynamic responses of aluminum alloy plates coated with polyurea elastomer subjected to repeated blast loads: Experimental and numerical investigation

As one of the commonly used component units of engineering structures, aluminum alloy plates will likely suffer from multiple blast loads in terrorist bombing attacks and industrial explosion accidents. Given such structures, the research of technical measures to resist extreme blast disasters is an important topic. Polyurea, is a potential excellent strategy for improving the blast resistance of aluminum alloy plates, with a promising application prospect. This study experimentally investigated the dynamic response and damage characteristics of polyurea-coated aluminum alloy plates under repeated blast loads, and the microscopic characteristics of polyurea material and Vickers hardness properties of aluminum material after loading were analyzed. Based on the developed numerical model, the plastic deformation and energy propagation laws of composite plates were analyzed. Finally, a parametric study on the coating position of polyurea, blast scaled distance, and number of blasts was conducted. The damage regularity of the aluminum plate was obtained, and the damage assessment was performed. The results revealed that polyurea coated on the back or double sides of the aluminum plate could exhibit improved blast resistance. Under repeated blasts, compared with that of the Category A plate (uncoated polyurea), the Category B plate (coated with polyurea on the back side) exhibited improvements of 33.9% and 31.3% in the local and overall deformation resistances, respectively. The Category C plate (coated with polyurea on both sides) exhibited improvements of 19.3% and 22.5%, respectively. Polyurea significantly alleviated the damage of the aluminum plates after two explosive loads.

Evaluation of Early-Stage Fatigue Damage in Metal Plates Using Quasi-Static Components of Low-Frequency Lamb Waves

Abstract Nonlinear Lamb waves including second harmonic and acoustic-radiation-induced quasi-static components (QSC) have a potential for accurately evaluating early-stage fatigue damage. Most previous studies focus on second-harmonic-based techniques that require phase velocity matching and are hard to isolate interferences from ultrasonic testing systems. The aforementioned requirement and deficiency limit applications of the second-harmonic-based techniques. In this study, a QSC-based technique of low-frequency Lamb waves is proposed for early-stage fatigue damage evaluation of metal plates, which does not need to require phase velocity matching and can remove interferences from ultrasonic testing systems. Both in simulations and in experiments, the primary Lamb wave mode at a low frequency that meets approximate group velocity matching with the generated QSC is selected. In finite element simulations, different levels of material nonlinearities by changing the third-order elastic constants are used to characterize levels of fatigue damage. Numerical results show that the magnitude of the generated QSC pulse increases with the levels of fatigue damage. Early-stage fatigue damage in aluminum plates with different fatigue cycles is further experimentally evaluated. The generated QSC pulse is extracted from received time-domain signals using the phase-inversion technique and low-pass digital filtering processing. The curve of the normalized relative acoustic nonlinearity parameter versus the cyclic loading number is obtained. Numerical simulations and experimental results show that the early-stage fatigue damage in aluminum plates can effectively be evaluated using the QSC generated by low-frequency Lamb waves.

Risk Assessment and Water Inrush Mechanism Study of Through-Type Fault Zone Based on Grey Correlation Degree

In order to effectively prevent and control the problem of water inrush from the through-type fault floor, based on the analysis of the case data of water inrush from the fault structure in the Fengfeng mining area, the types of karst water inrush from the floor are divided into 3 categories, 6 subcategories, and 17 fine categories. Four water inrush modes are summarized: composite structure water inrush, through-type fault water inrush, roof crack expansion water inrush, and floor vertical crack expansion water inrush. Based on the grey correlation theory and combined with the Analytic Hierarchy Process (AHP), this paper evaluates the water inrush risk of the F55-1 through-type fault zone from a micro individual perspective, taking the Xin’an Mine as the engineering background. Based on the water–rock coupling theory, the FLAC3D numerical simulation software is applied to study the disaster mechanism of the water inrush mode of the through-type fault. Through analyzing the changes of primary fracture stress and displacement of the intact floor strata and the aquifuge, and the pressure changes of confined water in fault zones, the collaborative water inrush mechanism of the damage and fracture of the bottom plate rock layer, the expansion and connection of the original fracture, and the seepage and progressive intrusion of the pressure water during the advancing process of the working face is analyzed. The research results indicate that the evaluation result of the water inrush risk of the F55-1 through-type fault in Xin’an Mine is Level I, belonging to the high risk and consistent with the actual situation model, verifying the rationality of the evaluation model. The process of water inrush in the numerical model is summarized as follows: a rock pressure failure zone is caused by the rupture and instability of floor aquifuge; a progressive intrusion zone develops—water inrush is connected between rock pressure failure zone and progressive intrusion zone; floor lagging flood occurs. Under the combined action of mine pressure and confined water pressure, the progressive intrusion height of confined water is significantly increased. The research results have important reference basis for future coal mining planning. This provides engineering reference and practical experience for the prevention and control of water damage in structured bottom plates under similar conditions.

Study on Time-frequency Imaging of Ultrasonic Detection with Phase Shifted Fiber Bragg Grating Sensing

Abstract The influence of the wavelength difference between the laser source and the phase-shifted fiber Bragg grating (PS-FBG) on the intensity of the power demodulation system based on an adjustable laser source was studied experimentally, and the optimum of the output laser wavelength was determined. Then, the research on time-frequency imaging damage identification based on smooth pseudo-Wigner-Ville distribution was carried out. The Time of Flight of the acoustic wave signal was calculated and time compensation was made according to the Wigner-Ville distribution and the Lamb wave dispersion curve. The ultrasonic waves before and after damage were measured with spatially arranged PS-FBGs. The difference signals were processed in a window, and then the time-frequency energy of the normalized difference signal was imaged to assess the damage detection and location. Although the mode and group velocity of ultrasound measured by each fiber grating were different, the accurate location and identification of artificial damage in an aluminum alloy plate was realized by using only three PS-FBGs and a smooth Wigner time-frequency imaging method.

Simulation and experimental study of fragment penetration into armored steel plate

In order to study the penetration ability of fragment simulation projectile(FSP) to armored steel target, and to detect the protection ability of target plates with different thicknesses. Combined with numerical simulation and experiment, the penetration process of FSP on armored steel target plates with different thickness ratios is studied. The design and implementation preparations were made for the damage of the steel target plate by the fragments, and the relevant data were obtained and analyzed. The analysis results show that the finite element analysis and the experimental study are in good agreement, and the ballistic limit of armored steel targets with different thicknesses and the calculation formula of the residual velocity of the FSP are obtained. The research results provide the basis and support for the evaluation, design and improvement of armored vehicle protection capability.

Study on Tensile Performance of Double-Bolted Joints between Carbon Fiber Reinforced Polymer Plate and Aluminum Plate

Carbon fiber reinforced polymer (CFRP) with high specific strength, specific modulus, and other outstanding properties, which could be used in aerospace, shipbuilding, and railway. The joint of carbon fiber composite material plate and metal material plate plays an important role in the overall performance of the structure. In this paper, a carbon fiber reinforced polymer (CFRP) progressive damage model is developed based on composite laminate theory and 3D Hashian theory. The model of the double bolt single lap joint shear connection is established for the CFRP plate and the finite element method is used to carry out the stress analysis and failure prediction of the lap structure. The effect on structural performance under tensile conditions was studied through the change of double bolt spacing. The results show that the decrease in bolt row spacing can lead to the interference effect between holes. In addition, the progressive damage of the composite plate is located near the center line of the bolt hole.