Defect Depth Research Articles

Investigating the failure mechanism of solid electrolyte interphase in silicon particles from an electrochemical-mechanical coupling perspective

Silicon is considered one of the most promising anode materials owing to its high theoretical energy density, however, the volume expansion/contraction during electrochemical lithiation/delithiation cycles leads to instability of the solid electrolyte interphase (SEI), which ultimately results in capacity degradation. Herein, the local stress and deformation evolution status of an SEI layer on an anode particle are investigated through a quantitative electrochemical-mechanical model. The impacts of structural uniformity, mechanical strength, and operating conditions on the stability of the SEI layer are investigated in detail. The simulation results demonstrate that when the silicon particle radius decreases from 800 ​nm to 600 and 400 ​nm, the failure time increases by 29% and 65%, respectively, of the original failure time; When the structural defect depth ratio is reduced from 0.6 to 0.4 and 0.2, the failure time increases by 72% and 132%, respectively; For the discharge rate, the condition at 0.1 C has 34% and 139% longer time to failure than that at 0.2 C and 0.3 C, respectively. This work provides insight into the rational design of stable SEI layers and sheds light on possible methods for constructing silicon-based lithium-ion batteries with longer cycling lives.

Failure pressure prediction of high-strength steel pipe bend considering pipe and corrosion geometry

This study examines the influence of pipe bend geometry and corrosion geometry on the failure pressure of high-strength steel pipe bends subjected to internal pressure and axial compressive stress. Finite element analysis determines the impact of bend angle, bending radius, defect depth, defect length, defect spacing, and axial compressive stress on failure pressures. The findings reveal that increasing the bend angle reduces failure pressures significantly, with corrosion defects exacerbating this effect. Increased bending radius increases normalized failure pressure from 0.88 to 0.91 for intrados defects and decreases it from 0.98 to 0.93 for extrados defects. Additionally, single defects cause a slight 2.5–3.0% reduction in normalized failure pressure, while longitudinally and circumferentially aligned defects result in a 13–15% decrease in normalized failure pressure. Defect depth and length also significantly influence the failure pressure, particularly for deeper and longer defects (up to 48.2%). Furthermore, an empirical equation for predicting failure pressures in corroded pipe bends with high accuracy (R2 = 0.99) is developed based on Artificial Neural Network. This enhances pipeline integrity assessment and design practices.

Two-dimensional line defect lattice solitons in nonlinear fractional Schrödinger equation

The existence, stability, and propagation dynamics of two-dimensional line defect lattice solitons (LDLSs) in a photorefractive crystal with focusing saturable nonlinearity under fractional diffraction effect are numerically investigated. It is shown that, the LDLSs stability domain narrows with increasing Lévy index in the semi-infinite bandgap either in the negative or positive defect lattice. While in the first bandgap, LDLSs are stable for the negative defect lattice and unstable for the positive defect lattice. Additionally, linear stability analysis indicates that the stability and power of LDLSs depend strongly on the Lévy index, defect depth, and propagation constant in different bandgaps. For LDLSs in the semi-infinite bandgap, the stability can be improved by decreasing either the Lévy index or the negative defect depth.

Detection Method for Bolt Loosening and Washer Damage in Flange Assembly Structures Based on Phased Array Ultrasonics

ABSTRACT During the service life of flange assembly components, factors such as corrosion and vibration can lead to washer damage and loosening of fastening bolts, resulting in fluid leakage. Traditional inspection methods are not applicable for assessing the extent of washer damage and bolt loosening due to the non-dismantlable nature of flanges and the challenges posed by the working environment. To address these issues, this paper proposes a detection method utilizing phased array ultrasonic testing (PAUT). By analyzing the peak and side-lobe states of reflected signals, the extent of washer damage can be determined. A mathematical relationship is established between the depth of washer defects and the peak reflection amplitude, enabling the assessment of washer damage in flange structures. This method facilitates the measurement of the positions of washer damage and bolt loosening in flange structures, providing technical support for practical industrial applications.

Detecting Cracks on Plates Using Reflections of Fundamental Symmetric and Anti-symmetric Lamb Waves from Defect

Introduction: Ultrasonic Lamb waves can achieve long-range inspection on plate-like structures and can even detect unreachable cracks and defects. There are multiple modes under a certain generation frequency with most of them dispersive. Method: The dispersion curves of Lamb wave in a steel plate were given by numerical calculation. A 2-D finite element (FE) model of a steel plate was promoted. The fundamental symmetric and antisymmetric Lamb waves were generated by uploading symmetrical and anti-symmetrical displacements on one side of the plane. The wave reflects when it comes across the defect and the edge of the plate. Mode conversion will occur after the asymmetrical discontinuities of the structure. Result: The theoretical and numerical results of the values of group velocities of S0 and A0 in a steel plate show well agreement. The maximum amplitude of the converted A0 wave from the interaction of the incident S0 wave with the cracks was observed. The amplitude will first rise then fall under any depth of the defects. The relationship between the defect reflection and the length as well as the depth of defects were simulated based on the FE model. Phase reversion and phase delay were discovered by controlling the defect size changing in one dimension. The reflection coefficient increases linearly with the defect length while the depth is constant, as well as the defect depth while the length is constant. method: Using finite element (FE) method to simulate Lamb wave motion in a plate, as well as experiments on steel plates with artificial defects. Conclusion: Experiments on steel plates with artificial defects including thorough holes and tapered holes were carried out using ISONICA STAR. The results also show that when the defect size changes in one dimension such as the thorough holes, the reflection coefficient increases linearly correspondingly. However, the testing results of the taper holes were inconsistent with the regulation as the size increases in both the length and the depth. result: The values of group velocities were calculated by time-of-flight method to identify specific modes. The results were calibrated and showed well agreement with theoretical data. Mode conversion will appear when the wave comes across asymmetric discontinuities of the structure.

Demineralized freeze-dried bone allograft with/without i-Platelet-rich fibrin in 3 wall intrabony defects

Demineralized freeze-dried bone allograft (DFDBA) contains bone morphogenetic proteins (BMPs), hence is osteoinductive. Autologous platelet concentrates exhibit a higher quantity of growth factors. Both these biomaterials aid in bone regeneration when placed in three-wall intrabony defects. However, their efficacy when used alone and in conjugation is not clear. Aim: To assess clinical and radiographic efficacy of injectable platelet-rich fibrin (i-PRF) with microsurgical access flap in the treatment of three-wall intrabony defects in chronic periodontitis patients. Methods: Thirty sites with three-wall intrabony defects were randomly assigned to control and test group by computer generated method. The test group obtained i-PRF mixed with DFDBA while the control group received only DFDBA. Clinical parameters such as site-specific Plaque index (PI), Radiographic intrabony defect depth (IBDD), modified- Sulcular bleeding index (mSBI), Clinical attachment level (CAL), and Probing pocket depth (PPD) were measured at baseline, three and six months. Results: Intragroup comparison within the control group and test group exhibited statistically highly significant variation of mean PI, mSBI, PPD, CAL, and IBDD score from baseline to 3 months and from 3-6 months (p<0.001). However, intergroup comparison demonstrated no statistically significant variation of mean IBDD at all 3 intervals (p>0.05). Conclusion: i-PRF combined with DFDBA enhanced the radiographic and clinical parameters as opposed to DFDBA alone. The role of i-PRF is promising in its capacity for easy obtainability and increased potential to aid in regeneration.

Quantification of depth and morphology of internal corrosion defects by stepped eddy current thermography skewness under weak excitation conditions

In the nondestructive testing (NDT) of eddy current thermography of oil and gas tanks, the low and non-uniform temperature rise due to weak excitation conditions makes the quantitative estimation of the depth and area of defects still challenging. This work proposes a mathematical-physical model of skewness to characterize defect depth quantitatively. The skewness image is estimated in Gaussian scale space using the background difference method combined with the chunked threshold segmentation method to characterize the defect morphology. The experimental results show that the skewness is affected by the combination of defect depth and area. As the defect area decreases, the relationship between defect depth and skewness gradually degrades from nonlinear to linear, while the rate of change of skewness becomes insignificant. The skewness analysis model predicted the maximum MRE of 5.15%, the minimum R2 of 0.94 for defect depth, and the MRE of 8.39% for defect area. It shows that the skewness can effectively characterize the depth and morphology of internal corrosion defects.

Dynamic Effect Analysis of Cryogenic Solid-Lubricated Ball Bearings with Geometrical-Frictional Defects

The traction behavior in cryogenic solid-lubricated ball bearings (CSLBBs) of liquid rocket engines (LREs) has a significant effect on the dynamic response of the bearing–rotor system. To reveal the fault mechanism of CSLBBs, a tribo-dynamic model is proposed in this paper that considers the solid-lubricated traction, six-DOF motion of the ball and contact collisions between the ball and the cage. The modified traction model uses fan-shaped and arched sections to discretize the contact area to eliminate the meshing error. The newly developed fault model, called ‘geometrical-frictional defects’, can more realistically represent solid-lubrication coating defects. The results show that the frictional excitation can significantly increase bearing vibration by increasing the traction force on the raceway. The change in the amplitude of the bearing vibration and its derivative can be used as a reference to determine the depth of defects. The width of the defect can be diagnosed by monitoring the double-pulse time interval and spectrum of the bearing vibration signal. This research may provide some theoretical guidance for the design and condition monitoring of CSLBBs.

Integra® Dermal Regeneration Template in Complex Scalp Reconstruction.

Background/Objectives: The need for surgical reconstruction of scalp defects following the excision of cutaneous skin cancers is an increasingly common procedure. Particular challenges arise when considering options for reconstruction of large defects not amenable to local skin flap coverage. The use of skin grafts poses the risk of donor site morbidity. This paper investigates the emerging use of Integra®, a synthetic acellular dermal regeneration template, as an alternative or adjunct to skin grafting in scalp reconstruction. Methods: The study presents a retrospective analysis of 101 patients who underwent Integra®-based reconstruction of scalp defects. Demographics, procedure details, complications, need for further surgery, and time to healing were evaluated. Results: The overall success rate of the one-stage Integra®-only procedure was 95%, with a minor complication rate of 30.7%. Anticoagulation medication was identified as an independent risk factor for post-operative infection, while previous head and neck radiotherapy and increased defect depth were associated with the requirement for a second-stage skin graft. Conclusions: These findings support the consideration of Integra® as a safe and viable alternative for both partial and full thickness scalp defects in a select cohort of complex highly co-morbid patients, reducing complications and the need for additional procedures.

A Multi-Source Data Fusion Network for Wood Surface Broken Defect Segmentation.

Wood surface broken defects seriously damage the structure of wooden products, these defects have to be detected and eliminated. However, current defect detection methods based on machine vision have difficulty distinguishing the interference, similar to the broken defects, such as stains and mineral lines, and can result in frequent false detections. To address this issue, a multi-source data fusion network based on U-Net is proposed for wood broken defect detection, combining image and depth data, to suppress the interference and achieve complete segmentation of the defects. To efficiently extract various semantic information of defects, an improved ResNet34 is designed to, respectively, generate multi-level features of the image and depth data, in which the depthwise separable convolution (DSC) and dilated convolution (DC) are introduced to decrease the computational expense and feature redundancy. To take full advantages of two types of data, an adaptive interacting fusion module (AIF) is designed to adaptively integrate them, thereby generating accurate feature representation of the broken defects. The experiments demonstrate that the multi-source data fusion network can effectively improve the detection accuracy of wood broken defects and reduce the false detections of interference, such as stains and mineral lines.

Accuracy improvement of inner defects of cylindrical components using ultrasonic detection with modified ALOK method

The accuracy of defect localisation and its size quantification is poor in the detection of internal defects of cylindrical components using the ultrasonic Amplituden und Laufzeit Orts-Kurven (ALOK) method. The influence of acoustic beam spread is not taken into consideration in the ultrasonic ALOK method, resulting in difficulties with the precise characterisation of the defect state. To address this, the relationship between the acoustic distance, amplitude, ultrasonic frequency, size and depth of hole defects was studied. The acoustic distance curve and the amplitude curve were fitted and then the localisation model of the defect was obtained. The acoustic beam spreading angle and echo sound pressure were introduced and then the size quantification model for defects was acquired based on principal component analysis (PCA). Both the simulated and experimental results show that the modified ALOK algorithm improved the detection accuracy of the defect location and its size and the relative error of defect sizing decreased by more than 35% compared with the original algorithm.

Study on the method of evaluating the failure of stator bar insulation materials based on mechanical damage characteristics

The damage impact of mechanical shocks on stator bar insulation is a key factor in high-voltage motor accidents. This study conducted electrical aging acceleration and breakdown experiments on damaged stator insulating materials to understand failure causes and evaluation methods. The relationship between sample defect area and depth and electrical properties was analyzed, along with the morphology of the damaged surface using a scanning electron microscope. Results show that the defect area correlates with impact mode but does not directly impact electrical performance. Effective insulation thickness is positively linked to electrical performance. This study serves as a valuable reference for evaluating mechanical impact faults in high-voltage motors.

Lower Extremity Trauma: A Multidimensional Reconstructive Approach with Hyperbaric Oxygen Therapy.

Background: Distal lower extremity reconstruction is challenging. This study aims to propose a protocol for the treatment of traumatic soft tissue defects. The key concept is to combine the surgical armamentarium of the reconstructive surgeon with the advantages provided by hyperbaric oxygen therapy. Methods: This retrospective study analyzed data of 57 patients affected with unilateral or bilateral lower extremity trauma distal to the knee and involving soft tissues with no indication of immediate reconstruction between 2010 and 2021. Before the reconstructive procedure, all the patients underwent a stick swab procedure for the collection of microbiological samples and debridement. Patients were divided into two treatment groups and only one group underwent a combined therapeutic procedure with hyperbaric oxygen therapy. Negative pressure wound therapy (NPWT) was employed only if deemed necessary according to the defect's depth and wound exudate. Surgical techniques, outcomes, and complications were discussed. Results: All patients achieved a complete recovery with no major complications and only minor complications observed. The study group treated with HBOT had a lower complication rate and lower percentages of minimal and partial graft loss compared with the same complications observed in the control group. No patients experienced HBOT-related complications. Significant reductions in the time to complete healing and the time from reconstruction to healing were found (p = 0.002 and p < 0.00001, respectively). Conclusions: A lower complication rate was observed in the group treated with HBOT. The administration of HBOT prior to soft tissue reconstruction significantly reduced the time to complete healing and the time interval from skin grafting to healing. However, prospective studies and randomized trials with larger cohorts should be designed to investigate the efficacy of HBOT for the treatment of lower extremity injuries with extensive soft tissue defects.

Failure Pressure Evaluation of Corroded Pipeline Using Semi-Empirical and Finite Element Analysis

Abstract Computational simulation using the finite element method (FEM) has proven to be one of the most efficient methods for the correct evaluation of the structural integrity of pipelines with corrosion-induced defects. In this paper, the results of the failure pressure of corroded pipelines obtained with a computer tool called PIPEFLAW based on nonlinear finite element analyses are presented and compared with the failure pressures of corroded pipes obtained with twelve (12) advanced semi-empirical models from the literature. A computational code was created in the Python language to automatically obtain the failure pressure of randomly generated cases of corroded pipes, which allows the analysis of multiple piping cases with isolated external corrosion defects in an idealized configuration. For this purpose, the LHS (Latin Hypercube Sampling) approach was adopted for the design of experiments to obtain a better distribution of cases in the sample space. Comparisons between the results using the FEM and semi-empirical models show, as expected, that the semi-empirical solutions are more conservative in most cases analyzed in this work. A statistical model is proposed that adheres to the relative error distribution for some of the models used. Moreover, the influence of some parameters (pipeline thickness, defect depth, defect length, defect width, yield stress and ultimate stress) on the failure pressure was evaluated. It was found that in most of the studied models the error increases as the defect depth increases.

A Distant Fasciocutaneous Chest Wall Skin Flap for Necrotic Finger Post Reimplantation: A Case Report

The hand is often compromised by scars or potentially necrotic wounds. Complete loss of index finger will result in impairment of 20% of hand and 11% of whole-person. One of the most influential factors in consideration of tissue loss are defect size, site, depth, and orientation. In our case study, a 16-year-old male presented with sensations of tingling and pain in his finger subsequent to an accidental laceration. Examination revealed a necrotic wound located on the distal phalanx of the index finger, accompanied by mild atrophy and discoloration. Subsequently, the patient underwent graft harvesting from the right chest wall flap, followed by primary closure of the donor site on the right chest wall. Upon a three-month follow-up, the patient expressed satisfaction, demonstrating proficient daily activities despite the injury being localized to the left hand. Utilizing a chest wall flap is less prevalent than employing regional or free flaps. Anterior chest wall flaps are specifically crafted on the anterolateral chest wall or within the infraclavicular region. The choice of a chest wall flap was determined to offer a less cumbersome graft and aligns with the patient's preference. The main goal of soft tissue reconstruction is to restore functionality, encompassing tasks such as exploration, sensation, and manipulation of objects, while simultaneously preserving the original length. Nonetheless, achieving this goal remains a complex challenge. Keywords: Necrotic finger, Reimplantation, Chest Wall Skin Flap, Soft Tissue Reconstruction

Comparative evaluation of treatment of angular bone defect related to over-erupted tooth using guided tissue regeneration (GTR) followed by orthodontic intrusion (OI) versus OI followed by GTR: a controlled clinical trial

BackgroundPrematurity resulted from pathological migration of periodontally involved teeth with the loss of vertical stopping points between teeth, which can lead to teeth over eruption with dimensional changes favoring occlusal discrepancies. Therefore, evaluating and comparing the effect of guided tissue regeneration followed by orthodontic intrusion as opposed to orthodontic intrusion tracked by guided tissue regeneration in the treatment of an over-erupted tooth with angular bone loss.MethodsTwenty teeth in ten cases were selected with at least two teeth with vertical over-eruption and angular bone loss with the presence of their opposing. In group one, ten teeth over-erupted were treated by guided tissue regeneration followed by orthodontic intrusion, whereas, in group two, ten teeth over-erupted were treated by orthodontic intrusion followed by guided tissue regeneration. They were evaluated clinically for pocket depth, bleeding on probing, and tooth mobility. Radiographical evaluation assessed by cone beam computed tomography.ResultsClinically, there existed a statistically significant difference (P value ≤ 0.05) in favor of group one at six months post and in favor of group two at one year from re-evaluation regarding pocket depth and tooth mobility. Radiographically, in group one, there was a statistically significant improvement (P value ≤ 0.05) at six months post-guided tissue regeneration or orthodontic intrusion regarding defect depth and dimensional changes of the defect area, with a statistically significant difference (P value ≤ 0.05) in favor of group two at one year from re-evaluation phase regarding defect depth and defect area dimensional changes.ConclusionThere was a short-term improvement in group one, which deteriorated over a long period compared with group two, so it is preferable to start orthodontic intrusion before guided tissue regeneration.

Enhancing resistance to low-velocity impact of electrospun-manufactured interlayer-strengthened CFRP by using infrared thermography

This study investigates the effect of electrospun nylon nanofibres modification on the low-velocity impact resistance of carbon fibre reinforced polymer (CFRP) laminates. Integration of multiple excitation infrared thermography using advanced image processing techniques is used to characterize the damage as a function of impact energy. The results show an enhanced damage resistance for the modified specimens, which is also validated by force – displacement curves. The interlaminar cracks show a maximum reduction of 24.8%, while delaminated areas and defect depths experience reductions of up to 28.7% and 24.3%, respectively. Interestingly, thermal diffusivity is introduced to identify the damage shape successfully. Finally, a correlation study is conducted, and a novel damage prediction model based on thermal diffusivity is proposed for further quantitative analysis.

Estimation of defect depth on plates by eddy-current coil array

Eddy-current (EC) testing is one of the contactless nondestructive testing techniques that has been frequently applied to evaluate the defects on metallic objects. In this paper, an estimation method of defect depth on metallic plates is proposed based on the approximate analytical model. An EC coil array sensitive to various defect orientation is designed to scan the plate surface. The independent inductance from various ferrite-core coil pairs can be found by the approximate analytical model. The influence of defect on measurements, including depth and edges, is regarded as the variation of probe lift-off in the tested region, defined as the equivalent lift-off. Based on the approximate analytical model, when defect edges have relatively smaller influence, the defect depth on the plate surface can be approximately obtained by estimating the equivalent probe lift-off through optimization. In numerical simulations and experiments, the proposed method is evaluated by testing the aluminum and stainless-steel plates with cracks by the coil array. The reconstructed equivalent lift-off distribution closely relates to the position and dimensions of defects on plates.

Evaluation of the Efficacy of Stem Cells Therapy in the Periodontal Regeneration: A Meta-Analysis and Mendelian Randomization Study.

Stem cell therapy for periodontal defects has shown good promise in preclinical studies. The purpose of this study was to evaluate the impact of stem cell support on the regeneration of both soft and hard tissues in periodontal treatment. PubMed, Cochrane Library, Embase, and Web of Science were searched and patients with periodontal defects who received stem cell therapy were included in this study. The quality of the included articles was assessed using Cochrane's tool for evaluating bias, and heterogeneity was analyzed using the I2 method. An Mendelian randomizationinvestigation was conducted using abstract data from the IEU public databases obtained through GWAS. Nine articles were included for the meta-analysis. Stem cell therapy effectively rebuilds periodontal tissues in patients with periodontal defects, as evidenced by a reduction in probing depth, clinical attachment level andbone defect depth . And delta-like homolog 1 is a protective factor against periodontal defects alternative indicator of tooth loosening. The findings of this research endorse the utilization of stem cell treatment for repairing periodontal defects in individuals suffering from periodontitis. It is recommended that additional extensive clinical investigations be carried out to validate the efficacy of stem cell therapy and encourage its widespread adoption.

Research on Alternating Current Field Measurement Method for Buried Defects of Titanium Alloy Aircraft Skin.

Titanium alloys are extensively used in the manufacturing of key components in aerospace engines and aircraft structures due to their excellent properties. However, aircraft skins in harsh operating environments are subjected to long-term corrosion and pressure concentrations, which can lead to the formation of cracks and other defects. In this paper, a detection probe is designed based on the principle of alternating current field measurement, which can effectively detect both surface and buried defects in thin-walled titanium alloy plates. A finite element simulation model of alternating current field measurement detection for buried defects in thin-walled TC4 titanium alloy plates is established using COMSOL 5.6 software. The influence of defect length, depth, and excitation frequency on the characteristic signals is investigated, and the detection probe is optimized. Simulation and experimental results demonstrate that the proposed detection probe exhibits high detection sensitivity to varying lengths and depths of buried defects, and can detect small cracks with a length of 3 mm and a burial depth of 2 mm, as well as deep defects with a length of 10 mm and a burial depth of 4 mm. The feasibility of this probe for detecting buried defects in titanium alloy aircraft skin is confirmed.