Rectangular Defects Research Articles

Time-varying Meshing Stiffness Calculation of Spur Gears with Asymmetric Spalling Defects

Gear systems are subjected to repeated loads during long-term operation, and factors such as insufficient lubricant to increase friction between gears, resulting in elevated temperatures and wear, are highly susceptible to tooth spalling. Tooth spalling is a common form of failure in gear failure. In previous studies, the vibration response of a gear pair with spalling defects at the tooth center near the pitch circle has been investigated. However, the location of the spalling defects offset from the center of the tooth flank is rarely studied. Tooth spalling faults occur in the pitch circle, but not necessarily in the center of the tooth, often formed on both sides of the center of the tooth and torsion in the meshing process. the symmetric and asymmetric rectangular spalling defects are considered, the torsional deformation is introduced. “torsional stiffness” is introduced into the overall TVMS due to the spalling defect. Therefore, it is meaningful to grasp the reasons for the formation of tooth spalling.

Quantitative Evaluation of Deformation in High-Speed Magnetic Flux Leakage Signals for Weld Defects in Oil and Gas Pipelines

Complex multiphase flow in oil and gas pipelines raises safety risks. Magnetic flux leakage (MFL) detection effectively identifies pipeline defects. However, the high-speed movement of MFL inspection tools induces motion-induced eddy currents (MIECs), complicating defect recognition and quantification. Most prior research has primarily focused on rectangular defects, leaving a gap in understanding the impact of MIECs on weld defects. This paper proposes the amplitude and shape deformation coefficients to analyze the influence of velocity on various weld defects, including internal reinforcement, lack of penetration, crack, external corrosion, internal corrosion, porosity, and lack of fusion. Utilizing these coefficients, this study examines the influence of the defect size and magnetizer configuration on these velocity-induced effects. The results show that the shape deformation coefficients range from 2.75 to 3.57 for Bx and from −0.13 to −0.3 for By, indicating a significant change in the MFL signal shape at 10 m/s compared to 0 m/s. The amplitude deformation coefficients for lack of penetration, internal corrosion, and porosity range from −0.01 to 0.1 for Bx, and from 0.86 to 0.98 for By, suggesting a decrease in peak-to-peak values. In contrast, other defects exhibit an increase in peak-to-peak values, indicating that the velocity effect may enhance the MFL signal. Also, the defect size and magnetizer configuration can affect the velocity effect on signals. These findings provide essential guidance for quantifying defect sizes and a solid foundation for designing more effective magnetization devices.

Mechanical properties of TPDH-graphene: atomistic aspect

Abstract TPDH-graphene is a new type of two-dimensional carbon material predicted by first-principles calculations to have tetragonal (T), pentagonal (P), decagonal (D) and hexagonal (H) carbon ring structures. First-principles calculations show that this special structure gives it excellent mechanical properties and promising applications in nanoelectronics. In this paper, a comprehensive test of its mechanical properties was carried out using the classical molecular dynamics (MD), mainly exploring the effects of factors such as tensile direction and temperature on its mechanical properties, and exploring the effects of introducing rectangular and circular defects on its mechanical properties. The results show that: TPDH-graphene exhibits significant anisotropy in zigzag and armchair directions, and the material exhibits some tensile toughness in armchair direction; the mechanical properties of the material are weakened at higher temperatures; the adding of defects leads to the reduction of the mechanical properties of the material in different directions to different degrees, and the The tensile toughness in the armchair direction is weakened by the addition of defects.

Measurement of surface rectangular defect depth based on laser-excited transmitted surface waves

ABSTRACT In order to study the effect of laser-excited surface waves on the transmission of surface rectangular defects, the transmission information of surface waves is used to achieve the quantitative calculation of defect depth. In this paper, the finite element method is employed to analyse the transmission process of laser-excited surface waves on rectangular defects. Subsequently, the influence of the front and back edges of rectangular defects on the transmission of surface waves is examined, and the formation mechanisms of feature points in the time-domain signals at detection points are elucidated. Ultimately, the calculation formula for defect depth is derived on the basis of the propagation path of each component after transmission. The experimental results are consistent with the simulation results, and the relative error of the surface rectangular defect depth calculation is within 9%. The validation of the proposed method on homogeneous isotropic metallic materials demonstrates the effectiveness and applicability of the proposed method. These results will provide a reliable method for characterising the depth of rectangular defects on surfaces by laser ultrasonic technology.

Time-varying displacement excitation and dynamic modeling of angular contact ball bearing with local defects

Angular contact ball bearings will produce fault damage when working for a long time, thus affecting the normal operation of the system. This paper takes angular contact ball bearings with local defects on the outer ring as the research object, proposes a method to distinguish different local defect profiles, establishes a generalized characterization model of time-varying displacement excitation of local defects in angular contact ball bearings, and studies the evolution process of local defects and their displacement excitation mechanism. On this basis, considering the influence of time-varying displacement caused by bearing defects on dynamic characteristics, based on Hertz contact theory, a fault dynamics model of angular contact ball bearings is established, and the correctness of the established model is verified by experiments. In addition, the analysis results show that rectangular local defects will eventually evolve into trapezoidal shapes; the displacement excitation change trends induced by different defect morphologies are different; compared with the length of local defects, the width has a greater impact on displacement excitation. The research results provide a theoretical basis for bearing optimization design and fault diagnosis.

Multi-frequency instantaneous wavenumber damage imaging method based on ultrasonic guided waves induced by laser point-by-point excitation

ABSTRACT A multi-frequency instantaneous wavenumber damage imaging method based on ultrasonic guided waves induced by laser point-by-point excitation is proposed in this paper. The experiment involved using the Nd:YAG pulsed laser is used as the excitation source to excite ultrasonic guided waves point-by-point in the detection area, and the piezoelectric ceramic transducer is used to receive ultrasonic guided wavefield at a fixed position. The wavefield information at different frequencies is extracted by a three-dimensional Fourier transform. The spatial phase distribution of the extracted guided wavefield with different frequencies is obtained by the Hilbert transform and phase unwrapping method. Then, the wavenumber of each detection point and the dispersion relations of the test piece with different thicknesses are calculated. Based on the calculated dispersion relation, the mapping relationship between the wavenumber and the thickness of the test piece is obtained. Furthermore, based on the obtained wavenumber information and wavenumber thickness mapping relationship, the thickness reduction depth of the defect can be calculated. Finally, the quantitative detection of defects is achieved through data fusion. The proposed method is verified through quantitative detection of the rectangular groove defects and the flat bottom defects with variable thickness and complex contour in the aluminium plate. At the same time, the detection results of the proposed method are compared with those of the single-frequency instantaneous wavenumber imaging method, single-frequency local wavenumber imaging method, and multi-frequency local wavenumber imaging method. In the detection results, the method proposed in this paper presents a better defect detection effect.

Modelling and experimental study on pipeline defect characterisations using a pulsed eddy current measurement

ABSTRACT Pipelines are widely used as the main transportation method in petrochemical and metallurgical industries. However, the special nature of the materials transported in pipelines means they are often subjected to high temperature, high pressure and corrosive conditions. This can lead to defects, such as thinning and cracking, resulting in pipeline failure and causing serious economic losses. Therefore, regular non-destructive testing of pipelines is particularly important. This paper uses the non-destructive testing method with pulsed eddy current technology to characterise pipeline thinning and defects. A preliminary study is conducted on the pulsed eddy current detection signal patterns for pipeline crack defects with varying orientations and quantities. A more portable pulsed eddy current detection device with an extended wall thickness detection range is developed. It can achieve measurements with a maximum thickness of 30 mm for detections of pipelines with rectangular defects and thickness-stepped reduced. The experimental results are consistent with modelling results, and the accuracy for pipelines with insulation layer is also investigated. On-site measurements using the PEC system are conducted on equipment sections with pipe thickness within 20 mm in a petrochemical plant. It is confirmed that the developed PEC inspection device can accurately characterises the thickness of pipelines with 0–50 mm cladding.

Behavior of eccentrically loaded slender concrete-filled steel tubes with defect representing random local corrosion

This paper focuses on the eccentric compression behavior of slender concrete-filled steel tubes (CFSTs) subjected to random localized corrosion and the localized corrosion was represented by a local defect. The randomness of corrosion includes the random locations and the random geometric characteristics that involve irregular corrosion profiles and uneven surfaces. Corrosion on the steel tube was represented by a defect in the experiment. The influence of spatial characteristics of local corrosion was investigated by seven CFST beam-column specimens, each featuring the defect in different locations along both height and circumferential directions. It was indicated through test results that both dimensions and locations of the defect considerably affected the failure mode and ultimate strength of the CFSTs. A numerical analysis was performed to confirm that local corrosion with irregular shape and uneven surface on a CFST beam-column can be approximated by a constant-depth circumscribed rectangular defect. Subsequently, a parametric analysis was conducted to find out how the corrosion dimensions, locations, and other critical parameters such as steel ratio, slenderness ratio, and material strengths influence the eccentric compression behavior of CFST. It revealed that negligible effects from local corrosion were observed in cases where slight corrosion was located near the column end. Finally, a calculation method was introduced to predict the ultimate strength of randomly localized corroded CFST beam-columns, with high precision.

Towards an optimization of automatic defect detection by artificial neural network using Lamb waves

This paper presents a damage detection method based on the inverse pattern recognition technique by artificial neural network (ANN) using ultrasonic waves. Lamb waves are guided elastic waves, are widely employed in nondestructive testing thanks to their attractive properties such as their sensitivity to the small defects. In this work, finite element method was conducted by Abaqus to study Lamb modes propagation. A data collection is performed by the signals recorded from the sensor of 300 models: healthy and damaged plates excited by a tone burst signal with the frequencies: 100 kHz, 125 kHz, 150 kHz, 175 kHz, 200 kHz, and 225 kHz. The captured signals in undamaged plat are the baseline, whereas the signals measured in damaged plates are recorded for various positions of external rectangular defects. To reduce the amount of training data, only two peaks of measured signals are required to be the input of the model. Continuous wavelet transform (CWT) was adopted to calculate the key features of the signal in the time domain. The feed forward neural network is implemented using MATLAB program. The data are divided as follows: 70% for training the model, 25% for the validation, and 5% for the test. The proposed model is accurate estimating the position of the defect with an accuracy of 99.98%.

Comparison of non-linear vibration of outer race defective ball bearing using two defect functions

The aim of this article is to study the effects of evolution in defect size on vibration of a ball bearing by simulation of a ball bearing by developing a 2-DOF mathematical model and to compare the vibration responses of defective bearings obtained for two widely used defect functions, viz., rectangular function and half-sine wave function. MATLAB codes are developed to prepare a mathematical model of a ball bearing and to solve the differential equations of the model using the Runge-Kutta method. In the model, the mass supported by the bearing is considered as a lumped mass, and the contact between the races and the balls is considered as a series of springs, whose spring stiffness is obtained by using Hertz’s contact deformation theory. This model considers the contact deformation between the balls and the races and the additional displacement between the balls and the inner race due to radial clearance and defect geometry. The maximum possible radial displacement of the ball into the defect is obtained analytically and graphically from the race-ball-defect geometry. First, the impulses generated due to an outer race defect in the ball bearing are modeled using two different defect functions separately and their vibration responses are compared. Secondly, the effects of increase in defect length on vibration of the bearing are simulated separately for two defect functions, and then their responses are compared and analyzed. The results show that when the defect is modeled with a rectangular defect function, the vibration responses obtained are greater than when the defect is modeled with a half-sine wave defect function. And, vibration responses increase rapidly up to a certain level of defect length and then decrease with a further increase in defect length. The vibration analysis performed for different defect lengths can provide good support to vibration analysts and researchers.

(171) Tunical Incision and Grafting for Severe Peyronie’s Disease Using Human Fascia Lata: Surgical Technique

Abstract Introduction Management of Peyronie’s disease is challenging for patients and can present with deformed penile angulation, pain, and reduction in erectile function. This video demonstrates the usage of cadaveric fascia lata grafting to rectify severe ventral penile curvature symptomatic of advanced Peyronie’s disease. Objective We outline a surgical technique to use fascia lata allografting for the correction of excessive ventral penile curvature caused by Peyronie’s disease if non-surgical treatments are insufficient. Methods A 65 year-old African-American male patient with severe Peyronie’s disease and a history of hypertension presented with a ventral penile curvature of 110 degrees at the proximal third of the shaft. Consequently, he was unable to engage in penetrative sexual intercourse. An artificial hydraulic erection confirmed the curvature, and the areas of fibrotic plaque were palpated. A degloving incision was made proximal to the glans, and a 6 cm segment of Buck’s fascia was elevated ventrally. The neurovascular bundle and urethra were separated from the corporae. A second hydraulic erection was induced, exposing a 6 cm by 3.5 cm rectangular tunical defect which was marked for excision. Bovie electrocautery was utilized to excise the fibrotic section of tunica albuginea. A rectangular section of Biosure human cadaveric fascia lata graft was soaked in saline solution and trimmed to 6 cm by 4 cm. The graft was sutured to the excised region of the tunica albuginea with 4–0 Maxon in a watertight fashion with a running stitch. A final hydraulic erection confirmed the mitigation of the penile curvature, and Buck’s fascia and the shaft skin were re-approximated to the subcoronal skin with 3–0 Vycril suture. Results This grafting procedure resulted in a near complete resolution of the ventral penile curvature with no complications. The patient was admitted overnight for observation and discharged POD 1 with a 3-layer dressing and mesh underwear. The postoperative penile length increased to 17.5cm from 16cm preoperatively as a result of the grafting and mitigation of the penile curvature. Conclusions Fascia lata allografts are robust and easily obtainable, which is ideal for the corporal reconstruction of fibrotic tunica albuginea in patients with Peyronie’s disease. This procedure demonstrates the utility of cadaveric fascia lata as an alternative surgical grafting material for the surgical correction of penile curvature associated with severe Peyronie’s disease. Disclosure No.

(192) Tunical Incision and Grafting for Severe Peyronie’s Disease Using Human Fascia Lata: Surgical Technique

Abstract Introduction Management of Peyronie’s disease is challenging for patients and can present with deformed penile angulation, pain, and reduction in erectile function. This video demonstrates the usage of cadaveric fascia lata grafting to rectify severe ventral penile curvature symptomatic of advanced Peyronie’s disease. Objective We outline a surgical technique to use fascia lata allografting for the correction of excessive ventral penile curvature caused by Peyronie’s disease if non-surgical treatments are insufficient. Methods A 65 year-old African-American male patient with severe Peyronie’s disease and a history of hypertension presented with a ventral penile curvature of 110 degrees at the proximal third of the shaft. Consequently, he was unable to engage in penetrative sexual intercourse. An artificial hydraulic erection confirmed the curvature, and the areas of fibrotic plaque were palpated. A degloving incision was made proximal to the glans, and a 6 cm segment of Buck’s fascia was elevated ventrally. The neurovascular bundle and urethra were separated from the corporae. A second hydraulic erection was induced, exposing a 6 cm by 3.5 cm rectangular tunical defect which was marked for excision. Bovie electrocautery was utilized to excise the fibrotic section of tunica albuginea. A rectangular section of Biosure human cadaveric fascia lata graft was soaked in saline solution and trimmed to 6 cm by 4 cm. The graft was sutured to the excised region of the tunica albuginea with 4-0 Maxon in a watertight fashion with a running stitch. A final hydraulic erection confirmed the mitigation of the penile curvature, and Buck’s fascia and the shaft skin were re-approximated to the subcoronal skin with 3-0 Vycril suture. Results This grafting procedure resulted in a near complete resolution of the ventral penile curvature with no complications. The patient was admitted overnight for observation and discharged POD 1 with a 3-layer dressing and mesh underwear. The postoperative penile length increased to 17.5cm from 16cm preoperatively as a result of the grafting and mitigation of the penile curvature. Conclusions Fascia lata allografts are robust and easily obtainable, which is ideal for the corporal reconstruction of fibrotic tunica albuginea in patients with Peyronie’s disease. This procedure demonstrates the utility of cadaveric fascia lata as an alternative surgical grafting material for the surgical correction of penile curvature associated with severe Peyronie’s disease. Disclosure No.

Detection of defects in printed circuit boards by the acoustic emission method

Objectives. Defects in the form of layering may occur during lamination in the production of multilayer printed circuit boards (MPCB). These defects cannot be detected by optical and electrical methods of output control. However, they can lead to breaches of the mechanical mode of operation and failures while running radioelectronic devices. In order to detect such defects, the acoustic emission (AE) method is proposed. This is based on the occurrence and propagation of acoustic waves in MPCBs caused by the presence of defects. The aim of this study is to investigate the possibility of using the AE method to detect defects in multilayer printed circuit boards. These defects can occur, in particular, in the lamination process.Methods. A mechanical processes modeling program (for research on the MPCB model) and various samples of two-layer printed circuit boards with pre-introduced defects (for experimental studies) were used to study the propagation of acoustic signals in the MPCB in the presence of defects. A solenoid mounted on the MPCB was used as a source of acoustic signals, while a piezoelectric sensor was used to receive signals. Data processing was carried out by comparing AE signals obtained for a serviceable MPCB sample and for MPCB samples with defects.Results. Simulation of the acoustic signal propagation in MPCBs in serviceable and faulty (with a rectangular defect in the form of delamination) states was carried out to show the difference in the received signals at the sensor installation point. Experimental studies were also conducted to examine the AE method applicability for detecting defects of various sizes and quantities.Conclusions. The studies demonstrated that the AE method allows the presence of defects in MPCB occurring during the lamination process to be detected effectively and reliably. This study proposes a new approach to non-destructive testing of MPCB using the AE method. This method significantly increases the reliability of MPCBs and the efficiency of their production processes.

Improved Deep Learning Model for Workpieces of Rectangular Pipeline Surface Defect Detection

This study introduces a novel approach to address challenges in workpiece surface defect identification. It presents an enhanced Single Shot MultiBox Detector model, incorporating attention mechanisms and multi-feature fusion. The research methodology involves carefully curating a dataset from authentic on-site factory production, enabling the training of a model with robust real-world generalization. Leveraging the Single Shot MultiBox Detector model lead to improvements integrating channel and spatial attention mechanisms in the feature extraction network. Diverse feature extraction methods enhance the network’s focus on crucial information, improving its defect detection efficacy. The proposed model achieves a significant Mean Average Precision (mAP) improvement, reaching 99.98% precision, a substantial 3% advancement over existing methodologies. Notably, the proposed model exhibits a tendency for the values of the P-R curves in object detection for each category to approach 1, which allows a better balance between the requirements of real-time detection and precision. Within the threshold range of 0.2 to 1, the model maintains a stable level of precision, consistently remaining between 0.99 and 1. In addition, the average running speed is 2 fps lower compared to other models, and the reduction in detection speed after the model improvement is kept within 1%. The experimental results indicate that the model excels in pixel-level defect identification, which is crucial for precise defect localization. Empirical experiments validate the algorithm’s superior performance. This research represents a pivotal advancement in workpiece surface defect identification, combining technological innovation with practical efficacy.

Double right triangular shape full-thickness skin grafts technique for short rectangular or square shape donor site defect - original method with a case report.

Full-thickness skin grafts are essential tools for reconstructive surgery. Rectangular or square secondary defect usually occurs after performing a cross-finger flap or homodigital island flap. With the traditional fusiform ellipse design, trimming out excess graft tissue is necessary. Double right triangular shape full-thickness skin grafts are designed to correct the problem.

Magnetic Dipole Model and Experimental Analysis of Magnetic Signal Detection Based on Magnetic Memory

By assuming that the magnetic charge is evenly distributed in the defect groove, the linear magnetic dipole is integrated in the depth direction of the defect, and the numerical calculation is carried out by using MATLAB to establish a two-dimensional magnetic dipole theoretical analysis model of double-correlated defects, which is suitable for analyzing the influence of stress on magnetic signal in the magnetic memory detection of rectangular and V-shaped combined macroscopic crack defects. To explore the influence factors and change rules of magnetic memory signal. In order to verify the correctness of the model analysis results, tensile tests were carried out on Q235 steel plate with double associated defects with different morphological characteristics, and the Hp(y) value of the normal component of the leakage magnetic field on the surface of the member was measured. The results show that the model based on magnetic dipole theory can explain some experimental phenomena and rules in magnetic memory detection.

The homogeneity effects of magnetic flux density distribution on the detection of railhead surface defects via the magnetic flux leakage method

Magnetic flux leakage (MFL) is a non-destructive testing method used to detect railhead surface defects. For effective MFL testing, the homogeneity of the magnetic flux density distribution (MFDD) within the railhead is crucial. Inhomogeneous formation of the MFDD within the railhead reduces the efficiency of the MFL testing. The homogeneity of the MFDD depends on the distance between poles (DBP) of the MFL testing system. According to the literature, as the DBP parameter increases, the MFDD becomes more homogeneous. In this study, four different homogeneity levels of the MFDD are introduced based on the DBP parameter. 3D finite element method (FEM) modelling simulation is conducted to obtain MFL testing analyses. The analyses are performed on a rail that contains rectangular surface defects of varying depth and length. The results of this study are evaluated using characteristic features of the MFL signal BX component, namely the slope of the baseline, the bottom value and the peak-to-peak value. The results show that if the homogeneity level of the MFDD within the railhead is higher, the bottom value and slope of the baseline decrease and the peak-to-peak value increases. This indicates that higher homogeneity of the MFDD enhances the detection efficiency of the MFL testing. Eventually, it is found that with the formation of nearly 100% homogeneous MFDD in the railhead, the slope of the baseline, the bottom value and the peak-to-peak value are enhanced by up to 83%, 77% and 12%, respectively.

Dynamically tunable multiple plasmon-induced transparency effect based on monolayer graphene structure system with rectangular defect cavities

In this article, a dynamically tunable multiple plasmon-induced transparency (PIT) effect in monolayer graphene structure system with rectangular defect cavities is investigated both theoretically and numerically. Because the graphene of our structure exists in a continuous form, the Fermi level of the graphene can be dynamically tuned by simply applying a bias voltage. The expressions of the theoretical transmittance are correctly deduced, and the fitting theoretical results are very consistent with the numerical simulation data. When the Fermi level of the graphene is increased from 0.8 eV to 1.2 eV, the group index of the dual-PIT system is controlled between 383 and 766. Alternatively, the group index of the triple-PIT system is maintained between 445 and 812. Moreover, the maximum group index can reach 812 at 1.2 eV, which shows that it can be designed as an excellent slow light device. Therefore, the proposed structures and results may provide strong guidance towards multichannel optical filters, dynamically tunable and excellent slow light and light storage devices.

A peridynamic model for rail crack initiation with cavity defect

Cavity defects can aggravate the rail crack initiation. To study their effect on rail fatigue crack initiation behaviour, a peridynamic model of rail crack initiation considering the characteristics of the cavity defect was proposed. First, based on the low-cycle fatigue test data, the bond failure criterion of the rail material was derived and verified to characterize the fatigue damage performance. Then, mathematical expressions for circular, triangular and rectangular defect characteristics were proposed, establishing a prefabricated method for rail cavity defects. Based on the ordinary state-based peridynamic fatigue theory, a rail crack initiation model with the cavity defect was constructed. Finally, the behaviour of rail crack initiation with the cavity defect was analysed.

Influence of tensile stress on the magnetic flux leakage signal of the coated steel belt

ABSTRACT The safety of coated steel belts (CSBs) is crucial for reliable elevator operation, as they are critical components in elevator systems. Magnetic flux leakage (MFL) testing is the preferred non-destructive method for evaluating CSBs due to its high sensitivity. Previous studies overlooked tensile stress's impact on in-service MFL testing of CSBs, potentially resulting in inaccurate defect assessments. This research aims to investigate the impact of tensile stress on the MFL signal of CSBs by developing a theoretical model, conducting finite element simulations, and performing experimental verification. In this paper, the rectangular edge defects are considered as the primary defect type in CSBs, and the applied stress on the CSBs varies from 30 MPa to 160 MPa. Under the above conditions, a linear relationship between MFL signal of CSBs and stress is established based on the simplified Jiles-Atherton model and magnetic dipole model suitable for CSBs. The finite element simulation and experiments further indicate that the MFL signal of CSBs increases linearly with the increasing tensile stress. The primary contributions of this study are establishing an MFL model suitable for CSBs and uncovering the linear relationship between the MFL signal of CSBs and tensile stress.