Crack In Strip Research Articles

Asphalt pavement crack detection based on infrared thermography and deep learning

ABSTRACT The current intelligent detection of asphalt pavement cracks relies on visible images, which are ineffective in handling temporary shadow and reflection. In contrast, infrared images reflect thermal radiation intensity, making them suitable for crack detection by mitigating environmental interference. The GSkYOLOv5 method is proposed in this study for accurate crack detection in infrared images of asphalt pavement. Firstly, an infrared dataset consisting of 2400 images of asphalt pavement cracks was captured and produced, including three types of cracks – strip cracks, cross cracks and reticular cracks. And the imbalanced samples were balanced using generative adversarial networks. Secondly, GhostNet and Selective Kernel Networks were added to enhance crack information perception, and the SPPF module was replaced to improve feature learning for different scale cracks. Lastly, GSkYOLOv5 was tested with a self-built infrared dataset of asphalt pavement cracks. GSkYOLOv5 improved detection accuracy by 4.7% and recall rate by 1.3% compared to YOLOv5s, outperforming the other tested algorithms. This method can be combined with visible image-based crack detection for comprehensive intelligent detection of asphalt pavement cracks using dual lenses for visible and infrared images.

Analytical Solution for a 1D Hexagonal Quasicrystal Strip with Two Collinear Mode-III Cracks Perpendicular to the Strip Boundaries

We considered the problem of determining the singular elastic fields in a one-dimensional (1D) hexagonal quasicrystal strip containing two collinear cracks perpendicular to the strip boundaries under antiplane shear loading. The Fourier series method was used to reduce the boundary value problem to triple series equations, then to singular integral equations with Cauchy kernel. The analytical solutions are in a closed form for the stress field, and the stress intensity factors and the energy release rates of the phonon and phason fields near the crack tip are expressed using the first and third complete elliptic integrals. The effects of the geometrical parameters of the crack configuration on the dimensionless stress intensity factors are presented graphically. The studied crack model can be used to solve the problems of a periodic array of two collinear cracks of equal length in a 1D hexagonal quasicrystal strip and an eccentric crack in a 1D hexagonal quasicrystal strip. The propagation of cracks produced during their manufacturing process may result in the premature failure of quasicrystalline materials. Therefore, it is very important to study the crack problem of quasicrystalline materials with defects as mentioned above. It can provide a theoretical basis for the application of quasicrystalline materials containing the above defects.

Bending of a plate with circular rigid inclusion and system of cracks on the assumption of strip crack face contact

The article presents a solution to the bending problem for an infinite isotropic plate with a circular rigid inclusion and arbitrarily oriented straight through cracks. It is assumed that under the action of an external load at infinity, the faces of all cracks are in smooth contact along a region of constant width near the upper surface of the plate. The solution is obtained using methods of the theory of functions of complex variable and complex potentials and is reduced to a system of singular integral equations, which is numerically solved by the mechanical quadrature method. On the basis of numerical analysis, the graphical dependences of the contact force, forces and moments intensity factors are constructed at various parameters of the problem.

Tearing behavior induced by van der Waals force at heterogeneous interface during two-dimensional MoS<sub>2</sub> nanoindentation

Combining with <i>in situ</i> nanomechanical testing system and video module of scanning electron microscope, the nanoindentation testing is performed to study the peeling-tearing behavior of two-dimensional material van der Waals heterostructures. After two-dimensional MoS<sub>2</sub> nanosheets prepared by chemical vapor deposition are assembled into MoS<sub>2</sub>/SiO<sub>2</sub> heterostructures by wet transfer, the nanoindentation is carried out by manipulating the tungsten probe in the<i> in situ</i> nanomechanical testing system. When the tungsten probe is tightly indenting into MoS<sub>2</sub> nanosheets, a new W/MoS<sub>2</sub>/SiO<sub>2</sub> heterostructure is assembled. With the tungsten probe retracting, the adhesive effect makes the two-dimensional MoS<sub>2</sub> nanosheet peel off from SiO<sub>2</sub>/Si substrate to form a bulge. After reaching a certain height, under the van der Waals adhesion interaction, an incomplete penetration fracture occurs along the arc line contacting the needle. Then cleavage appears and produces two strip cracks and MoS<sub>2</sub>/SiO<sub>2</sub> interface separation takes place simultaneously, before a large area of MoS<sub>2</sub> nanosheet is teared. Based on the density functional theory calculation of interface binding energy density of van der Waals heterogeneous interface, the interface binding energy density of MoS<sub>2</sub>/W is verified to be larger than that of MoS<sub>2</sub>/SiO<sub>2</sub>, which explains the adhesion peeling behavior of MoS<sub>2</sub> induced by van der Waals force between heterogeneous interfaces, perfectly. By using the peeling height and tearing length of MoS<sub>2</sub> recorded by video module, the fracture strength of MoS<sub>2</sub> is obtained to be 27.055 GPa and stress-strain relation can be achieved according to the film tearing model. The density functional theory simulation results show that the fracture strength of MoS<sub>2</sub> is in a range of 21.7–32.5 GPa, and the stress-strain relation is consistent with the experimental result measured based on film tearing model. The present work is expected to play an important role in measuring the fracture strengths of two-dimensional materials, the assembly, disassembly manipulation and reliability design of two-dimensional materials and van der Waals heterostructures devices.

VMFNet: visual-microwave dual-modality real-time target detection model for detecting damage to curved radar absorbing materials.

Damage to radar absorbing materials (RAMs) reduces the stealth capabilities and battlefield survivability of the equipment. Research on RAM damage detection technology is key to outfield equipment maintenance. In this paper, an intelligent RAM damage detection method based on visual and microwave modalities is proposed. A compressed sensing planar-scanning microwave imaging method based on a range migration algorithm (RMA) imaging operator and fast Gaussian gridding nonuniform fast Fourier transform (FGG-NUFFT) is proposed, achieving high imaging quality and speed. A dual-modality, curved RAM dataset (DCR dataset) is constructed, composed of visual images and microwave images showing two kinds of damage: round shedding and strip cracks. A new dual-modality target detection model, the visual-microwave fusion network (VMFNet), is designed to detect RAM damage. Its mean average precision (mAP) reaches 81.87%, and its inference speed reaches 35.91 fps. A visual network (VisNet) and microwave network (MicNet) are designed as the backbone of VMFNet for extracting the visual and microwave features of RAMs. A path aggregation network (PANet) unit is designed to fuse the multiscale features of the two modalities, resulting in good retention of shallow-level features and high detection accuracy. The head contains different receptive fields and outputs three scales of detection results, effectively detecting damage of different sizes.

Dynamic splitting tensile behaviours of distilled-water and river-water ice using a modified SHPB setup

The tensile strength of ice subjected to dynamic loading constitutes many ice engineering applications such as ice blasting and hail-aircraft impact. In this study, the dynamic tensile behaviours of distilled-water and river-water ice were firstly investigated using the flattened Brazilian disc method with a modified split Hopkinson pressure bar system. Columnar freshwater ice samples were tested at strain rates ranging from 20 to 135 s−1 and temperatures ranging from −5 to −45 °C. The effects of impact velocity, loading rate, and ice sample thickness on the dynamic splitting tensile strength were also explored. Distilled-water ice specimens exhibited a higher indirect tensile strength than their river-water counterparts. The lower the temperature, the greater is the tensile strength, particularly in the case of distilled-water ice in the strain rate range of 89–135 s−1. The temperature had less effect on the dynamic tensile strength of distilled-water ice compared to the loading rate, and the specimen thickness had little effect on the dynamic indirect tensile strength. A large number of non-penetrating cracks were observed on the disc surface, indicating the inhomogeneous distribution of the tensile stress interpreted based on the 3D Brazilian disc theory. The closer the two end faces in the central cross section, the greater the tensile stress. The presence of single and multiple strip cracks on the splitting surface were discovered, possibly because of the instant expansion of the ice specimen and subsequent formation of mode-I cracks in the thickness direction.

A Robust Automated Vision Based Filamentous Steel Strip Crack Detection System Based on Neuron Model Segmentation

Crack detection has always been a dominant requirement for steel industries to ensure quality production and seamless infrastructure maintenance. However, application complexities and defect morphological differences make existing approaches confined. Steel-strip surface often undergoes scratch, crack and fatigue conditions during production. Manual crack detection schemes are no longer effective in current day complex environment. Amongst major steel strip crack detection approaches vision based techniques have found potential; Filamentous crack which is caused due to fatigue or strain is fine-grained and thin and hence highly difficult to be detected by classical morphology and static threshold based schemes. In the present work steel strip surface (filamentous) crack detection system has been developed which employs Varying-Morphological Segmentation (VMS) also called Neuron-Model Segmentation (NMS) in conjunction with local directive filtering and active contour propagation. The proposed method can be stated as an augmented variational framework that employs multi-directional filters for local crack-region identification followed by automated multi-directional region growing and iterative contour evolution which performs level set energy minimization to achieve accurate crack detection even under topological non-linearity and varying illumination conditions Simulation results with standard benchmark data has confirmed that the proposed method exhibits satisfactory performance for steel strip surface cracks.

Propagation Law of Stress Wave and Cracks in Non-penetrating Jointed Rock Mass: A Numerical Study Based on Particle Flow Code

It is important to study the interaction between stress wave propagation and rock joints to prevent dynamic disasters in rock mass engineering. In this manuscript, the numerical SHPB system and sandstone rock model were established firstly and then considering different joint vertical and horizontal distance analyzed the propagation law of stress wave and cracks. The research results show that the vertical and horizontal distance of the joints affect the waveform, rise time, wave coefficient of the transmitted and reflected stress wave when compared with the intact rock specimens. The crack propagation process can be divided into three stages. Under the influence of the joint vertical distance, the cracks spread like a “circle” and with the increase of the joint vertical distance, the size of the crack “circle” increases. Besides, there are some cracks spread like a “circle” within a certain horizontal distance with the vertical distance fixed. However, with the increase of the horizontal distance, the circle shape of the cracks change into a slanted crack strip when beyond a certain horizontal distance.

Pure Bending of Strip (BEAM) with Crack in Strip of Tensile Stress with Allowance for Plastic Strips Near Crack Tips

Abstract In the article, the pure bending problem for strip (beam) with straight, perpendicular to its axis crack located in the zone of tensile stresses is investigated on the assumption of narrow plastic strips near crack tips. Using methods of the theory of functions of a complex variable and complex potentials, the problem is reduced to the several linear conjunction problems. The solutions of latter problems are obtained in the class of functions confined in the edges of plastic strips. Formulas for the calculation of their lengths are derived. Expressions for the determination of crack tip opening values are written. Numerical analysis of the problem is performed.

Non‐uniformly loaded stack of moving elastic antiplane shear cracks

AbstractA stack of moving, non‐uniformly loaded, parallel, antiplane shear strip cracks within an isotropic elastic solid is analyzed, by exploiting an extended dislocation layer technique using moving screw dislocations. Detailed closed‐form expressions are obtained and discussed for the stress components at general points of the deformation that is created. Their variations with the polar angle near a crack tip are investigated and a neat representation of the corresponding novel, comprehensive, stress intensity factor is deduced. Illustrative numerical results are graphically presented. The occurrence of the phenomena of crack branching and crack shielding are observed for particular values of the geometrical parameters and speed of the cracks. Comparisons with some corresponding special cases are provided as validation of these more general results.

Highly Robust and Automated Vision based Filamentous Steel Strip Crack Detection System

Crack detection has always been a dominant requirement for steel industries to ensure quality production and seamless infrastructure maintenance. However, application complexities and defect morphological differences make existing approaches confined. Steel-strip surface often undergoes scratch, crack and fatigue conditions during production. Manual crack detection schemes are no longer effective in current day complex environment. Amongst major steel strip crack detection approaches vision based techniques have found potential; Filamentous crack which is caused due to fatigue or strain is fine-grained and thin and hence highly difficult to be detected by classical morphology and static threshold based schemes. In the present work steel strip surface (filamentous) crack detection system is developed which employs Varying-Morphological Segmentation (VMS) also called Neuron-Model Segmentation (NMS) in conjunction with local directive filtering and active contour propagation. The proposed method can be stated as an augmented vibrational framework that employs multi-directional filters for local crack-region identification followed by automated multi-directional region growing and iterative contour evolution which performs level set energy minimization to achieve accurate crack detection even under topological non-linearity and varying illumination conditions Simulation results with standard benchmark data has confirmed that the proposed method exhibits satisfactory performance for steel strip surface cracks.

Seismic damage mechanism of bedrock and overburden layer slope reinforced by sheet pile wall

Abstract Sheet pile walls, widely used in landslide control projects, have demonstrated excellent seismic performance during the great Wenchuan earthquake, as indicated by an investigation of retaining walls following earthquake damage. To further understand the mechanism of seismic damage based on the Hilbert–Huang transform method and marginal spectrum identification theory, a large-scale shaking table test of bedrock and overburden layer slope reinforced by sheet pile wall was carried out, and the mechanism of seismic damage was analysed. The results show that the change in marginal spectrum amplitude and characteristic frequency can clearly indicate the degree of seismic damage to the slope soil. First, the dynamic response of the slope soil near sheet pile wall is smaller than the response observed in soil farther from the wall, and the degree of seismic damage near the wall is relatively weaker than that farther away from the wall. Second, the energy of the seismic wave cannot be completely transferred behind the wall, and the strip cracks of soil behind the wall can be determined. Finally, the slope soil slides along a slip surface so that the front edge of the slope is squeezed due to the vertical tensile cracks at the rear edge. In addition, the results confirm the feasibility of the Hilbert–Huang transform method for studying the mechanism of the seismic damage to the structure-soil coupling system.

Design of the Fall-Block Sensing of the Railway Line Pantograph Based on 3D Machine Vision Sensors.

As an important part of the electric locomotive in railway transportation, the sensing and inspection of the pantograph has a significant effect on the safe operation of the train. In general, the pantograph carbon slip detection items include slide wear detection, slip strip crack detection, carbon slip fall-block detection and slip strip wear detection. The emergence and development of structured light measurement technology with 3D sensors provide new technical means for the acquisition of spatial 3D information. The three-dimensional data can not only obtain more information but also reduce the data deviation, thereby improving the measurement accuracy and work efficiency. At present, few studies have been conducted on the slide block and partial wear of the carbon slide. Therefore, this paper studies the detection of the pantograph slide block based on 3D sensor measurement technology. The experimental results indicate that it is feasible to adopt 3D measurement technology to detect the fall-block of the pantograph slide. In addition, a sound detection effect can also be obtained.

Intermetallic Growth Induced Large-Scale Void Growth and Cracking Failure in Line-Type Cu/Solder/Cu Joints Under Current Stressing

In order to study the electromigration (EM) behavior of solder joints in electronics packaging, especially under high-current and high-temperature working conditions, line-type Cu/solder/Cu butting samples were prepared to observe the microstructural evolution under 1.0 × 104 A/cm2 current stressing. A prominent polarity effect was found such that the Cu6Sn5 intermetallic compound (IMC) layer at the anode side, which thickened linearly with time, was much thicker than that at the cathode side. Compared to the samples subjected to thermal aging at the same temperature of 180°C, EM enhanced the Cu3Sn growth at both the anode and the cathode. Two distinct types of damage were observed after extended duration of current stressing. Back-flow of Cu into Cu3Sn was found at the Cu3Sn/Cu6Sn5 interface of the anode side, causing large voids, while strip cracks developed at the cathode solder/Cu6Sn5 interface, causing a significant increase of joint electrical resistance. With the mass transport characteristics that determine the IMC growth and vacancy accumulation analyzed in detail at each interface, formation mechanisms of the two types of damages are discussed.

正交各向异性带型中裂纹诱导的温度场分析

正交各向异性带型中裂纹诱导的温度场分析

A non-uniformly loaded anti-plane crack embedded in a half-space of a one-dimensional piezoelectric quasicrystal

Closed-form representations are obtained using an extension of the classical continuous dislocation layer method combined with a method of images for the components of the phonon and phason stress and electric displacement fields around a generally loaded strip crack in a half-space of one-dimensional hexagonal piezoelectric quasicrystalline material parallel to its free surface. Representative numerical data are presented graphically.

Равновесие составной упругой плоскости, содержащей полосу и симметрично расположенные взаимно перпендикулярные трещины.

Равновесие составной упругой плоскости, содержащей полосу и симметрично расположенные взаимно перпендикулярные трещины.

One-dimensional piezoelectric quasicrystals with an embedded moving, non-uniformly loaded shear crack

Closed-form expressions are derived and discussed, using an extended dislocation layer method, for the components of the stress and electric fields created by a moving non-constantly loaded antiplane, Griffith-type strip crack within one-dimensional piezoelectric quasicrystals. Some typical numerical results are displayed graphically. Explicit results for the fields of an analogous stationary crack subjected to non-constant loading are derived, as a special case.

An antiplane shear crack moving in one-dimensional hexagonal quasicrystals

An investigation is presented of an antiplane shear strip crack subjected to representative general non-constant crack-face loading conditions which is moving uniformly in one-dimensional hexagonal quasicrystals, using an extended technique of continuous dislocation layers. Readily-calculable explicit closed-form representations are determined and discussed for the components of the phonon and phason stress fields created throughout the media. Illustrative numerical results are presented graphically. As a special case, the corresponding expressions are deduced explicitly for a non-uniformly loaded stationary crack.

Равновесие упругой плоскости, содержащей полосу и симметричные трещины на линиях контакта.

Равновесие упругой плоскости, содержащей полосу и симметричные трещины на линиях контакта.