Defect Depth Research Articles

Strength Analysis of Corroded Seawater Pipeline Based on Finite Element Method

The residual strength of corroded defective pipelines is an important manifestation of pipeline-bearing capacity. The change of residual strength of Q235 steel and B10 Cu-Ni alloy pipeline caused by the change of defect depth, length, and width in the case of grooved corrosion defect was analyzed and studied by the finite element method. The results show that the effect of corrosion defect depth on the residual strength is greater than the defect length and width. At the same time, Q235 steel has better pressure-bearing performance than B10 Cu-Ni alloy.

Defect-aware Super-resolution Thermography by Adversarial Learning

Infrared thermography is a valuable non-destructive tool for inspection of materials. It measures the surface temperature evolution, from which hidden defects may be detected. Yet, thermal cameras typically have a low native spatial resolution resulting in a blurry and low-quality thermal image sequence and videos. In this study, a novel adversarial deep learning framework, called Dual-IRT-GAN, is proposed for performing super-resolution tasks. The proposed Dual-IRT-GAN attempts to achieve the objective of improving local texture details, as well as highlighting defective regions. The generated high-resolution images are then delivered to the discriminator for adversarial training using GAN's framework. The proposed Dual-IRT-GAN model, which is trained on an exclusive virtual dataset, is demonstrated on experimental thermographic data obtained from fibre reinforced polymers having a variety of defect types, sizes, and depths. The obtained results show its high performance in maintaining background colour consistency and removing undesired noise, and in highlighting defect zones with finer detailed textures in highresolution.

Detection and Measurement of Pitting Corrosion using Short Range Guided Wave Scanning

Short range guided wave scanning is an inspection method enabling an indirect, quantitative measurement of remaining pipe wall thickness. It has seen widespread industrial use as an inspection solution for corrosion under pipe support (e.g. [1]). Pitting corrosion represents a significant challenge in industrial pipelines and its presence complicates short range guided wave scanning analysis as the wavelength used for inspection is larger than the diameter of small pitting-type defects. This work investigates the reflected signal from pitting corrosion, both in isolation and in the presence of larger corrosion patches, to improve the understanding of the complex signals received. This work provides the foundation and guidance for analysis techniques used in guided wave scanning. To achieve this a series of representative pitting defects with varying diameter and depth have been investigated using explicit finite element modelling. It is shown that using currently established analysis techniques, the pit depth can be quantified for pitting with a diameter larger than approximately 13 mm. Smaller diameter pitting may only be qualitatively detected at this time due to mode conversion occurring at the defect, which obscure features that are used to provide quantitative analysis of the defect depth. Quantitative sizing of defects where pitting is present will require further investigation.

Analytical Methods for Calculating Dimensional Uncertainty In Ultrasonic Testing

This paper depicts a project undertaken in the offices at Defence Research development Organisation (DRDO), Gas Turbine Research Establishment (GTRE)) Bangalore. Non-Destructive Testing (NDT) methods are used to determine the integrity and reliability of parts without impairing their future usability. They can be classified as methods used for the detection of Surface, Internal anomalies. Ultrasonic Testing is a versatile NDT method which can be used for both the above purposes and use high-frequency sound waves (above 20 KHz) to penetrate the object and conduct the examination. This method was selected for the purpose of estimating the associated dimensional uncertainties while sizing the defects. Specimens were manufactured with artificial holes of 0.5 mm diameter and varying depths in cylinders made out of work-house aerospace materials of Ti-64 (blades and disks of a compressor), Su-718 (Super alloy used for hot end parts) and S-80 (stainless steel used for gear parts) in conformance to international standards. These blocks were subjected to Contact and Immersion Ultrasonic Testing methods. Transducers (probes) of two different frequencies (5 MHz and 10 MHz) were chosen for both the methods to understand the effect of probe sensitivity on the uncertainty estimation. For each of the blocks conducted three different trials for the measured depth of defect Vs actual depth of defect and values were tabulated. Regression Analysis was chosen for obtaining the Type-A uncertainty owing to the availability of limited data and linear relationship among the variables, while Type-B was derived from standard statistical calculations specified in "Guide to Expression of Uncertainty in Measurement" (GUM) as per ISO 17025 and combination of random and systematic errors. Standard uncertainty was calculated for both Type-A and B methods. Combined uncertainty was derived which represents the contribution of ultrasonic system, calibration blocks along with measurement results. The expanded uncertainty represents the combined uncertainty with a confidence interval of k=2 (i.e. 95 % confidence level).The combined and expanded uncertainty were obtained by Type B method. It was analysed and concluded that Type-A is conservative in approach and under estimates standard uncertainty values, whereas Type-B results in higher estimates. The results show that the uncertainties are sensitive to variations associated with material attenuation property, defect diameter, probe frequency.

Comparative evaluation of the clinical and radiographic efficacy of 0.05% zoledronate gel as local drug delivery system in treating intrabony defects in stage III grade B periodontitis patients with and without type-2 diabetes mellitus-A randomized split-mouth clinical trial.

This 6-month randomized split-mouth and placebo-controlled clinical trial aimed to evaluate the clinical and radiographic efficacy of adjunctive use of 0.05% zoledronate (ZLN) gel as local drug delivery to scaling and root planing (SRP) in stage III, grade B periodontitis patients with and without controlled type-2 diabetes mellitus (DM). A total of 120 infrabony sites were divided into two groups: Group-1 (non-diabetic periodontitis) and Group-2 (periodontitis +DM). A total of 60 sites in each group were randomized to receive treatment with SRP+placebo gel (control) or SRP+0.05% ZLN gel (test). Plaque index (PI), modified sulcus bleeding index (mSBI), pocket probing depth (PPD), and relative attachment levels (RAL) were assessed at baseline, 3 and 6 months, and digital intraoral periapical and cone-beam computed tomography imaging were used to measure the linear and percentage reduction of intrabony defect depth (DD, DDR%) after 6 months. Group-1 showed significant reduction in PI (0.56±0.15 and 0.52±0.19 from 0.67±0.17), mSBI (0.7± 0.60 and 0.47± 0.57 from 0.9±0.48), PPD (4.6± 0.85 and 3.43 ± 0.63 from 6.5±1.04) and gain in RAL (7.03±0.85 and 5.93 ± 0.69 from 8.9±1.09) in the ZLN-treated sites than the placebo sites and also from Group-2 sites after 3 and 6 months, respectively. A significant reduction in DD of 28.79% in Group-1 and 22.20% in Group-2 at ZLN sites was seen compared to placebo sites of both groups. ZLN gel applied subgingivally in infrabony pockets resulted in significant clinical improvements evident by probing depth reduction and gain in attachment levels along with radiographic evidence of more bone fill seen in non-diabetic patients compared to diabetic periodontitis patients.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ТОКАРНОЙ ОБРАБОТКИ ЖАРОПРОЧНЫХ СПЛАВОВ ВВЕДЕНИЕМ В ЗОНУ РЕЗАНИЯ ЭНЕРГИИ УЛЬТРАЗВУКОВОГО ПОЛЯ

The use of difficult-to-process heat-resistant alloys is widely used in the design of aircraft engines and gas pumping units. As a rule, thin-walled shell structures are made from them, providing a high density of the layout (for example, blades, electric unicycles). The peculiarity of the manufac-ture of such structures is a small (compared to the occupied volume of the entire product) volume of metal, in which the heat generated during shaping is distributed. Given the low thermal conductivity of such alloys (up to 4-5 times less compared to steels), the shaping of parts from them is associated with the risk of warping in combination with low productivity of blade processing with carbide tools. More effective, but little studied is the processing with tools made of mineral ceramics with the introduction of the energy of the ultrasonic field into the cutting zone. The purpose of the research is to develop a high-performance technology for pre-processing workpieces made of heat-resistant alloys with tools made of mineral ceramics, characterized by a minimum depth of defects in the surface layer.
 Methods. The research was carried out on machine tools in the manufacture of non-rigid parts of aircraft by turning blanks from the heat-resistant alloy HN45MVTYUBR with cutters made of mineral ceramics with the introduction of the energy of the ultrasonic field into the processing zone. 
 It has been established that the use of ultrasonic vibrations during pretreatment with mineral-ceramic tools without coolant can reduce the depth of the defective layer by up to one and a half times and increase productivity by up to 30 times.
 Taking into account the reduction in the depth of the defective layer, it becomes possible to reduce the allowances for final processing, and consequently, to reduce the duration of the technological process and the cost of manufacturing parts.

The defect depth evaluation based on the dual-sensor strategy: Resisting the lift-off disturbance in magnetic flux leakage testing

The quantitative evaluation of defect information is the key issue in magnetic flux leakage (MFL) nondestructive testing on ferromagnetic materials. For the multi-sensor strategy with the same lift-off values, the arrayed layout of probes improves the testing efficiency, but the evaluation precision is still susceptible to the lift-off disturbance. This paper recommends a dual-sensor strategy with a given lift-off difference to resist the lift-off disturbance. Here, the reason for the possible overestimating and underestimating evaluation is clarified for the traditional single-sensor strategy using the magnetic dipole theory in MFL testing. In this paper, the effectiveness of the proposed dual-sensor strategy is demonstrated by comparison with the traditional single-sensor strategy. Analysis shows that the proposed dual-sensor strategy in MFL testing can overcome the lift-off disturbance and improve evaluation precision of the defect depth in cases with uncertain lift-off values. This study provides a path for the quantitative evaluation of MFL testing based on the dual-sensor strategy.

Infrared defect recognition technology for composite materials

This study mainly involves the methods and experiments of using infrared thermal wave imaging detection technology to detect internal defects in aircraft composite materials. The results were discussed and analyzed. In this paper, the feasibility of the experiment was verified by simulation. In simulation, the minimum accuracy of detectable defects is 4 mm radius under the mesh division accuracy with a correlation coefficient of 5. On this basis, an accurate detection method and prototype nondestructive testing system for defects of aircraft composite materials based on infrared imaging detection technology were designed, which can realize the identification and positioning of defects in aircraft composite material structures, including type, size and accurate depth of defects. Finally, the data collected by the infrared detection system was recognized through YOLO neural network. The test result shows the confidence level for water point defect is more than 0.9, while the confidence level for crack defect is about 0.5. This research result will expand the use case of infrared nondestructive testing technology around the world, and the transformation of the results will help to solve the maintenance problems of aircraft in general aviation.

Research on internal defect detection of epoxy glass fiber composites based on terahertz imaging technology

Composite materials are characterized by light weight and high specific strength, which have been widely used in the field of transportation. The rapid and non-destructive detection of defects in the process of composite material production can be regarded as the key and guarantee for the safety. In this paper, the terahertz imaging technology was used to explore the detection of epoxy glass fiber composite samples with varied defects. Terahertz time-domain spectroscopy (THz-TDS) of different depths of defects in epoxy glass fiber samples were corrected by multiple pretreatment methods. Different variable selection methods were used to screen the spectral data. The Partial Least Squares (PLS) and Least Squares Support Vector Machines (LS-SVM) defect depth quantitative models were established, respectively. The visualization of the defect area is achieved by combining with different types of binary threshold segmentation methods. It was found that the ALS-SPA-LS-SVM model presents the best effects, and Rp and RMSEP of prediction set are 0.9998 and 0.0152 respectively. The grayscale histogram bimodal method has the best effect on detecting the defect area. It is feasible to detect the defects in epoxy glass fiber by THz-TDS combined with LS-SVM and image processing technology, which can achieve rapid and nondestructive detection of the location, depth and area of the defects. It provides the technical basis for defect detection in the process of composite material production. In this way, this study provides new methods and means for defect detection and quality supervision of other types of composite materials.

Reconstruction of Scalp and Forehead Defects: Options and Strategies.

Background Aesthetic reconstruction of scalp and forehead defects with local flaps and minimal donor site morbidity is the primary goal of coverage. While selecting the coverage technique, essential factors such as size, location, and components of a defect, hair-bearing or non-hair-bearing nature of skin, status of the exposed skull, need for radiation, patient condition, availability of local tissue, and the potential for hairline distortion should be kept in mind. Materials and methods This is a retrospective analysis in which 54 patients who underwent soft tissue reconstruction of the scalp and forehead defects were included. The defect size was categorized into four groups: small: <4 cm2, medium: 4-50 cm2, large: 50-200 cm2,and very large: >200 cm2. Reconstruction of all defects was done according to the defect's size, location, and depth. All patients were regularly followed at intervals of two weeks, six weeks, and three months, respectively. The outcome was evaluated in terms of flap survival, flap coverage scale, the requirement of secondary treatment, postoperative complications, and final aesthetic appearance. Results In 54 consecutively treated patients with scalp and forehead defects, the male-to-female ratio was 2:1, and the overall mean age of participants was 34.8 years, ranging from 0.5 to 66 years. The most common etiology of the defect was trauma (16; 29.6%), and the most common location of the defect was combined (16; 29.6%). Rotation flap and primary closure were the most commonly performed procedure, each 12 (22.2%) in number. Out of 12 primary closure cases, two patients developed wound dehiscence because of infection. All cases ofskin grafting healed well. All cases of transposition flap with skin grafting at the donor site went uneventful, and the dog ear at the base was revised later. One case of the bipedicle flap in which partial graft loss occurred at the donor area was managed with regrafting. Two cases of single rotation flap, one double rotation flap, and one free latissimus dorsi muscle flap developed distal necrosis. The excellent aesthetic outcome was found in all cases of primary closure and single and double rotation flaps. Conclusions Local flaps have an architecture similar to the recipient site, and low donor site morbidity results in an aesthetically more pleasant outcome. In our experience, scalp defects up to 50 cm2 were covered with the local scalp flaps with primary closure of the donor area. Defects ranging from 50 to 200 cm2 required local scalp flap with skin grafting at the donor area.Free tissue transfers are usually needed when the defect is very large, devoid of the periosteum, or with the calvarial defect.

Numerical analysis and experimental research on detection of welding defects in pipelines based on magnetic flux leakage

Regular inspection of long-distance oil and gas pipelines plays an important role in ensuring the safe transportation of oil and gas, and inspection on welding defects is an important part of the inspection process. Magnetic flux leakage (MFL) is an electromagnetic non-destructive testing technique which has been commonly utilized to detect welding defects in pipelines. In the present study, Maxwell electromagnetic simulation software was used to carry out numerical study on the welding defects in pipelines, including incomplete penetration and undercut. The Ф406 pipeline with a wall thickness of 7 mm was selected as the study case to establish the numerical model. Setting the life-off value at 1 mm, the distribution of magnetic leakage field was investigated for pipeline without defect, pipeline with incomplete penetration defect and pipeline with undercut defect respectively, the characteristic values describing the depth and width of defects were found. Furthermore, quantified equations which can be used to describe the defect depth were proposed. Finally, experimental research was carried out to validate the effectiveness of the numerical model, and the experimental results showed good consistence with the numerical calculation results. The research results indicate that, it is technically feasible and reliable to diagnose the incomplete penetration and undercut welding defects in pipelines using MFL.

Treatment of furcation defects using various bone grafts and guided tissue regeneration membranes: A review on single-center institutional studies

Abstract Bone formation in class II furcation is least due to the morphology of the root in case of multirooted teeth performed by conventional procedure. Hence, various bone grafts with membranes have been tried in the current study to evaluate its efficacy by comparing test and control groups. This collection of research from a single center presents a bone graft and guided tissue regeneration (GTR) membrane-based furcation therapy. Bio-Oss and Bio-Gide, PerioGlas and Atrisorb, Periobone G and Resolut XT, as well as PepGen P-15 and Atrisorb, were among the bone graft materials used, both with and without the GTR barrier. Patients were divided into four groups based on the periodontal regenerative materials used. A periodontal flap procedure was performed where periodontal intraosseous defect along with furcation defects were present. The results show that the bone formation in the furcation area was more with Group C (Periobone G and Resolut XT) as compared to the least amount of bone formation in Group A (Bio-Oss and Bio-Gide) in the test group, and this same group shows least bone formation in control. To conclude, clinical outcomes observed with the combined use of Atrisorb as a GTR barrier and PerioGlas as a bone graft material improved the clinical measurements of furcation defect depth compared to the use of PerioGlas alone.

Two-stage method of free gingival graft prior to periodontal regenerative surgery for the treatment of intrabony defects with insufficient keratinised tissue width: a study protocol for an open-label randomised controlled trial

IntroductionGuided tissue regeneration (GTR) combined with bone grafting for periodontal regenerative surgery has ideal clinical results for intrabony defect. However, some sites of intrabony defects often suffer from insufficient keratinised...

Forecasting pipeline safety and remaining life with machine learning methods and SHAP interaction values

In-line inspection (ILI) is a common and useful way to provide comprehensive threat assessments and to detect defect dimensions. However, the ILI is very expensive and most of its costs are unnecessary since very few pipelines contain defects. Many previous studies have used machine learning (ML) methods to predict the safety of pipelines based on the features extracted from ILI signal results, which is very laborious and difficult to apply in industry. In this paper, the ILI results were predicted using multiple ML models through three prediction cases with only pipeline attributes and environmental features as input variables. In the first case, six ML methods were compared to predict whether there are defects in a pipeline section. The Catboost (CAT) method showed the best performance in all evaluation metrics with the highest certain prediction ratio (94%). The second case was using three ML methods to predict a defect depth, defect length, and defect width. The prediction accuracy of the defect depth was much higher than that of the defect length and defect width. A CAT model was the optimal model in this case due to its best performance in all the predictions. In the third prediction case, three ML methods were used to predict a defect length growth rate and defect depth growth rate based on different ILI results from different years. CAT was also the best method in this case with the highest accuracy. The predicted defect length growth rate and defect depth growth rate were used to calculate the remaining lifetime of pipelines based on the maximum allowable defect depth and failure pressure. The remaining lifetime of pipelines with different thickness, land use, and soil types was analyzed with changes in the specified minimum yield strength of a pipeline, a pipeline year, and maximum operating pressure. The accurate predictions in the three cases and the correlation analysis between input features and outputs helped company save a lot of costs and provided valuable information and suggestions in the further progress.

Clinical and Radiological Benefits of Hyaluronic Acid in Periodontal Infrabony Defects: A Systematic Review and Meta-analysis

Purpose:There is no consensus on the clinical and radiological benefits of hyaluronic acid (HA) in patients with periodontitis having infrabony defects. Hence, this study examined the effects of HA in periodontitis patients with infrabony defects through a comprehensive systematic review process.Methodology:A systematic literature search was performed using PubMed/Medline, Scopus, Embase and Cochrane Library from inception to March 2022. Randomized or non-randomized clinical trials and single-arm clinical trials that assessed the clinical and radiological benefits of HA in periodontitis patients with infrabony defects with a minimum of 6 months follow-up were included in this study. Surgical regenerative therapy was considered as the comparator. The Cochrane risk of bias assessment tool and Downs and Black checklist was used for the quality assessment of randomized and non-randomized interventional studies, respectively. A subgroup and sensitivity analyses were performed to explore the heterogeneity and robustness of the findings, respectively.Results:A total of 13 out of 725 studies were included in this systematic review, of which 9 were considered for meta-analysis. The meta-analysis indicated significant benefits of HA in terms of reduction in probing pocket depth (SMD: 1.12 mm; 95% CI: 0.60-1.65; 9 studies), bone defect depth (SMD: 1.04mm; 95%CI: 0.62-1.47; 3 studies) and gain in clinical attachment level (1.04 mm; 95% CI: 0.33-2.47; 8 studies). Overall, the quality of included studies was good.Conclusion:The current evidence indicates that the administration of HA in the periodontal regenerative treatment of infrabony defects was significantly effective in increasing clinical attachment levels and reducing probing pocket and bone defect depth.

The development of modern diagnostic methods and means of controlling the initiation of microcracks in metal structures that are in a stress-deformed state

The possibility of detecting the depth of a micro defect in metals has been proved at the moment of its formation under the action of a load based on the results of simultaneous monitoring of temperature changes on the opposite surfaces of the object of control. Taking into account the fact that in the case of the formation of a defect at a depth other than ½ the sample thickness along its central axis, there will be a time delay in the observation of the maximum temperature on the opposite surfaces of the object of study. The research results are the basis for improving the existing method and system for controlling the moment of microcrack initiation.

Long-Term Outcome and Athletic Level following Operative Treatment for Osteochondritis Dissecans of the Knee in Pediatric and Adolescent Patients.

Research on the long-term outcomes following surgical therapy for osteochondritis dissecans (OCD) of the knee is scarce. A single-center retrospective cohort study was conducted to investigate surgically treated patients for knee OCD between 1993 and 2007. A total of 37 patients with an average follow-up duration of 14 years (range 8-18) were in the final cohort. IKDC and Lysholm scores were assessed. The duration and types of sport activity were reported. Long-term results were compared with existing midterm data. Knee scores showed a very good outcome with a mean of 91.3 in the IKDC score and 91.7 in the Lysholm score. Compared to midterm outcomes, both IKDC (p = 0.028) and Lysholm scores (p = 0.01) improved on final follow-up. Patients with open physes showed a significantly better Lysholm score compared to patients with closed physes (p = 0.034). Defect localization and size did not influence the outcome, but a defect depth of <0.8 cm2 achieved significantly better scores than ≥0.8 cm2. Of all surgical interventions, refixation achieved the best outcome. Long-term results significantly improved compared to midterm results with a follow-up of 40 months (p = 0.01). Thirty-six out of 37 patients were physically active, with 56% of sports being knee-straining activities. Long-term results following surgically treated OCD fragments show excellent function and a good athletic level. Patients with open physes potentially have better knee outcomes. Midterm results are sustainable and could improve further in the long term.

A thickness reduction testing method for ferromagnetic materials based on variable intensity DC magnetization

The assessments of internal thickness reduction of ferromagnetic components are extremely important. Traditional nondestructive testing (NDT) methods are usually non-linear and sometimes the electromagnetic parameters of components are required. In this paper, a thickness reduction testing method based on variable intensity DC magnetization (VIDC-MAG) is proposed. Both theoretical modeling analysis and simulation modeling analysis show that a pole point of magnetic permeability μm appears with the increase of DC magnetization intensity, which corresponds to an inflection point magnetizing current im. The im decreases with the increase of the defect depth of the wall thickness reduction and shows a linear relationship. The experimental results show that the method performs well for the inner wall thickness thinning and the relative error of the measurement results is small. Additionally, the measurement results are related to the width of the thickness reduction, the probe excitation frequency, the magnetic properties of ferromagnetic material and the lift-off distance of the magnetizer. The method is applicable to the thickness variation of the cover layer and does not need to know the electromagnetic parameters of the components in advance, which has greater practical application value.

Quantitative Evaluation of Corrosion Defects on Structural Steel Plates via Metal Magnetic Memory Method

ABSTRACT The detection and evaluation of corrosion defects take on a critical significance to ensure the service safety of steel structures in civil engineering. The quantitative evaluation of corrosion defects has not been well addressed though metal magnetic memory (MMM) testing technology has been investigated in steel corrosion problems. In this study, the Q345qD steel plates were taken as the specimens of MMM testing. Specimens with different corrosion degrees were developed through electrochemical corrosion, and the change laws of the MMM signals and the characteristics of different corrosion specimens were analyzed. A three-dimensional (3D) magnetic charge model of the corrosion area was built based on the magnetic charge theory, such that the change laws of the MMM signal in the corrosion area from the mechanism were explained. The finite element simulation results of the corrosion specimens were well consistent with the experimental and theoretical results. A quantitative evaluation method for corrosion defect depth was proposed in combination with finite element simulation and experimental data. Comparing the experimental data and the inversion data, the relative errors of the determined defect depth h were within 20%, suggesting that the proposed evaluation method is feasible for the quantitative evaluation of steel corrosion depth.

Automatic defect detection and three-dimensional reconstruction from pulsed thermography images based on a bidirectional long-short term memory network

Machine learning techniques have become increasingly applied to non-destructive testing based on pulsed thermography. However, existing methods need to extract characteristic data manually. The present work addresses this issue by applying a bidirectional long-short term memory (Bi-LSTM) network to identify defects, predict defect depths, and reconstruct defective materials in three dimensions automatically based on raw cooling data sequences. The network is trained and tested based on data collected for stainless-steel specimens with multiple flat-bottom holes introduced at various specimen depths. A dual-task method and a single-task method were proposed based on Bi-LSTM network. A classification model and a regression model are constructed in the dual-task method for identifying defects and predicting defect depths. Only the regression network is implemented in a single-task method to more quickly obtain the same results based on a depth threshold. Both methods are demonstrated to achieve satisfactory accuracy in the 3D reconstruction of the defects in the testing specimen. In addition, higher pulse energy and faster acquisition frequency can promote the prediction accuracy. Then the results of Bi-LSTM were compared with the results of 1D CNN and MLP. To verify the generalization of the proposed method, CFRP specimen is employed for 3D reconstruction, which also performed with good results.