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Abstract The tensile properties of coal under dynamic loading are important mechanical characteristics of coal and are highly important for controlling coal rock stability under impact loading conditions, selecting blasting engineering parameters, and studying the mechanism of rockburst disasters. To investigate the dynamic tensile failure process of coal subjected to impact loading, this study used high-speed photography and digital image correlation technology to capture the dynamic tensile failure of coal under impact loading. The dynamic tensile evolution was quantitatively analyzed from the beginning of coal sample being loaded to failure. The captured images of the coal were processed, and the fractal dimension was used to quantitatively describe the evolution of the coal surface cracks under impact loading. The following conclusions were drawn from the experimental results: (1) An empirical formula was established to describe the dynamic tensile strength characteristics of coal under different loading rates. (2) Under impact loading, the maximum strain of a Brazilian disc coal sample first appeared at the contact end between the sample and the incident rod. (3) Under impact loading, a Brazilian disc coal sample cracked from the center of the sample outward, and the crack subsequently extended toward both ends. The fractal dimension of the crack exhibited a power function relationship with time, and the variation range of the fractal dimension of the crack was 1.05–1.39.

In this study, we present a new implementation of the phase field fracture approach in the finite element code ANSYS and its numerical background. The framework is general, and is supported by addressing several classical 2D boundary value problems as well as the ductile fracture and 3D surface flaws behaviors of particular interest. The 3D implementation exploits the analogy between the phase field formulations and the magnetic vector potential equation. The influence of the mode mixity and biaxiality loading conditions of the cracked bodies on phase fields is evaluated as a function of the crack length scale parameter, characterising the scale at which damage effects become significant. As a result of the FE calculations of phase field distributions for propagating cracks, the effects of both the fracture mode and the biaxial stress-strain state are determined. The size of the fracture process zone or damaged region is determined across a wide range of cracked body loading conditions. Developed code: https://github.com/Andrey-Fog/ANSYS-USERELEMENT-PHFLD.

Sintered sludge ash (SSA) represents a promising alternative to traditional cement, offering a potential pathway for reducing carbon emissions. This study examined the flexural performance of SSA-modified cement paste (SSC paste) at varying SSA proportions (S0 (0%), S1 (5%), S2 (15%), and S3 (25%)) and employed innovative digital image correlation (DIC) technology to track the evolution of surface cracks during flexural strength testing. Furthermore, Griffith’s theory of fracture toughness was employed to evaluate the fracture performance of SSC paste. The observations of flexural strength at 3, 7, and 28 days indicated that the content of SSA had an adverse effect on flexural performance. Furthermore, the monitoring of cracks confirmed the practicality of DIC in evaluating flexural properties. The analysis of maximum strain and crack propagation via DIC revealed a distinct trend: the presence of 5% SSA inhibited crack propagation and enhanced flexural ductility, whereas the presence of 25% SSA produced the opposite effect. This was corroborated by fracture toughness calculations based on Griffith’s theory. It is noteworthy that 15% SSA represented a critical threshold that delineated variations in flexural strength, ductility, and fracture toughness, which may be linked to the Ca/Si and Ca/Al ratios in the composite matrix. This study demonstrates the innovative application of digital image correlation (DIC) in the monitoring of crack behavior and offers new insights into the crucial proportion of SSA that affects the mechanical properties of SSC paste.

Gas absorption and emission characteristics are very important for the prediction, inspection and prevention of coal and gas outburst disasters, which are related to the structural distribution characteristics of coal fractures closely. In this paper, the coal samples of No.2, No.4, No.8 and No.9 coal seams in Dongqu Coal Mine are selected, and the fractal dimension is used to quantitatively characterize the distribution of coal surface fractures. The relationship is studied between the characteristic parameters of fracture distribution and gas absorption and emission. The results show that the fractal dimension parameters of the fracture distribution on the coal surface are solved by fitting based on the fractal theory. The value range of the fractal dimension parameters is 1.4-1.5, and the development degree of primary fractures is No.9 coal seam>No.4 coal seam>No.8 coal seam>No.2 coal seam. The isothermal adsorption constants of coal and the initial velocity of gas emission are analyzed through the gas adsorption and emission experiment. The value range of adsorption constants a is 34.180-36.920 m3/t, while the value range of initial velocity of gas emission is 12-18 mL/s, which is consistent with the fractal dimension value. The correlation between fractal dimension parameters and gas adsorption and emission parameters of coal in Dongqu Coal Mine are statistically analyzed. It shows that there is a significant positive correlation between them. The fractal dimension value can characterize the values and capabilities of gas adsorption and emission of coal in this coal mine.

Surface cracks are alluded to as one of the early signs of potential damage to infrastructures. In the same vein, their detection is an imperative task to preserve the structural health and safety of bridges. Human-based visual inspection is acknowledged as the most prevalent means of assessing infrastructures’ performance conditions. Nonetheless, it is unreliable, tedious, hazardous, and labor-intensive. This state of affairs calls for the development of a novel YOLOv8-AFPN-MPD-IoU model for instance segmentation and quantification of bridge surface cracks. Firstly, YOLOv8s-Seg is selected as the backbone network to carry out instance segmentation. In addition, an asymptotic feature pyramid network (AFPN) is incorporated to ameliorate feature fusion and overall performance. Thirdly, the minimum point distance (MPD) is introduced as a loss function as a way to better explore the geometric features of surface cracks. Finally, the middle aisle transformation is amalgamated with Euclidean distance to compute the length and width of segmented cracks. Analytical comparisons reveal that this developed deep learning network surpasses several contemporary models, including YOLOv8n, YOLOv8s, YOLOv8m, YOLOv8l, and Mask-RCNN. The YOLOv8s + AFPN + MPDIoU model attains a precision rate of 90.7%, a recall of 70.4%, an F1-score of 79.27%, mAP50 of 75.3%, and mAP75 of 74.80%. In contrast to alternative models, our proposed approach exhibits enhancements across performance metrics, with the F1-score, mAP50, and mAP75 increasing by a minimum of 0.46%, 1.3%, and 1.4%, respectively. The margin of error in the measurement model calculations is maintained at or below 5%. Therefore, the developed model can serve as a useful tool for the accurate characterization and quantification of different types of bridge surface cracks.

Structural deterioration is a primary long-term concern resulting from material wear and tear, events, solicitations, and disasters that can progressively compromise the integrity of a cement-based structure until it suddenly collapses, becoming a potential and latent danger to the public. For many years, manual visual inspection has been the only viable structural health monitoring (SHM) solution. Technological advances have led to the development of sensors and devices suitable for the early detection of changes in structures and materials using automated or semi-automated approaches. Recently, solutions based on computer vision, imaging, and video signal analysis have gained momentum in SHM due to increased processing and storage performance, the ability to easily monitor inaccessible areas (e.g., through drones and robots), and recent progress in artificial intelligence fueling automated recognition and classification processes. This paper summarizes the most recent studies (2018–2022) that have proposed solutions for the SHM of infrastructures based on optical devices, computer vision, and image processing approaches. The preliminary analysis revealed an initial subdivision into two macro-categories: studies that implemented vision systems and studies that accessed image datasets. Each study was then analyzed in more detail to present a qualitative description related to the target structures, type of monitoring, instrumentation and data source, methodological approach, and main results, thus providing a more comprehensive overview of the recent applications in SHM and facilitating comparisons between the studies.

Taking Daliuta Coal Mine in Western Shendong mining area as the engineering background, this paper selected typical shallow buried high-intensity mining panel 52307 to establish the observation station for surface movement. Combined RTK technology and 3D laser scanning technology for real-time monitoring, based on key layer theory and CISPM comprehensive surface subsidence prediction model software, the characteristics of surface movement and deformation, surface movement angular parameters and surface cracks in high-intensity mining of shallow buried was studied. The results showed that with the advance of the panel from the set-up room, the surface subsidence was small at the set-up room position and then increased suddenly and rapidly. Simultaneously, the subsidence curve became steep sharply. When the maximum subsidence value was reached, the subsidence velocity tended to slow down. The surface movement deformation was mainly concentrated in the middle of the panel, while the subsidence deformation around the panel and the influence range of surface movement was small. The surface movement angular parameters were quite larger in the Daliuta coal mine area, while the bedrock movement angle and boundary angle reached 87.7 ° and 84.1 ° respectively. The surface cracks caused by mining were in an overall “C” shape, mainly distributed in the middle of the panel. Then, As the working face continued to advance, the ground fissures continue to slowly extend, develop, and gradually close from the set-up room to the tailgate side, eventually forming a continuous surrounding "funnel" shape. Ground fissures always lagged behind the working face position and the lag distance of surface cracks increases linearly with the mining speed. According to the analysis of surface subsidence law and surface cracks development, it was concluded that under the condition of high-intensity mining of shallow buried with thick coal seam, due to the high mining intensity of the working face, fast advancing speed, single key layer structure and low occurrence horizon, the roof activity was intense and easy to slide and lose stability. As a result, it was appeared resulting in rapid convergence around the surface movement basin, serious damage in the middle, and intensive development of ground fissures.

To solve the problems of low efficiency and high risk of crack detection in high-rise buildings, the author proposes a building crack image acquisition and processing system based on unmanned aerial vehicle (UAV), expounds the working principle of the system, and analyzes the selection of hardware in the system. The experiment is carried out by combining the acquisition system with the image processing system of the ground station. Based on the characteristics of building surface crack image, an adaptive filtering method is introduced to improve the classic system file checker combination method. The experimental results show that the accuracy of Canny’s method was 96.88%. Canny-based crack target detection method is trained and tested on the crack data set to obtain the classification results and the best detection effect. It is proved that the Canny algorithm based on UAV images can effectively detect cracks on building surface.

Yushenfu mining area, with large scale and high intensity, is an important raw coal-producing area in northern Shaanxi, but the fragile ecological environment makes the mine geological environment problems caused by coal mining particularly relevant. To grasp the development law of surface cracks and reveal the formation mechanism caused by coal mining in the Yushenfu mining area, the typical working faces of Anshan Coal Mine, Caragana Tower Coal Mine, and No. 1 Coal Mine of Xiaobaodang in the Yushenfu Mining area were chosen as the research object to conduct the study. The results show that the surface cracks can be divided into four types: step type, extrusion uplift type, sliding type, and tension type, as well as two combination modes of collapse, trough and parallel. In the Yushenfu mining area, the spatial distribution law of surface cracks is relatively unified. The performance characteristics of surface cracks are different and negatively correlated with the ratio of mining depth to mining thickness. The surface cracks induced by very shallow coal seam mining, shallow coal seam mining, and medium-deep coal seam mining have the dynamic law of lagging mining position 1.0 m, advanced mining position 8.5 m, and lagging mining position 30.14 m, respectively, and the relationship between the lag distance of surface cracks and the ratio of mining depth to mining thickness is a polynomial function. The characteristic of the width of boundary cracks and forward slope cracks in the working face was increased until stable. In contrast to the boundary cracks, the characteristic of the width of the reverse slope fractures increases and then decreases, and the width of the cracks in the flat area in the working face increases first, then declines, and then increases. The average activity time was 3.7–7.0 days. The crack with the activity of “opening first and then closing” is controlled by the dynamic evolution of overlying rock structure, and the fracture with the activity of “only opening and then closing” and “opening first and then closing” was controlled by surface dynamic evolution. However, the activation mechanism of slope fracture is closely related to slope slip. The findings of this study can provide theoretical guidance for surface crack control and ecological restoration in the Yushenfu mining area.

In the paper, N1212 working face was taken as the research object, the law and mechanism of surface cracks in shallow coal seam mining were studied by means of field investigation, dynamic monitoring and numerical simulation. The results show that the development degree of surface cracks in shallow coal seam mining is high, mainly “step” cracks, and the in-plane cracks are distributed at parallel intervals with an interval distance of 8-15 m. The cracks have two kinds of activity characteristics: “opening-closing” and “only opening and disconnecting”; the stress evolution and failure in the overlying strata extend forward in the form of “arch”, and the overlying rock fissures and surface cracks are connected with each other; the advanced generation and activity characteristics of surface cracks are closely related to surface movement and deformation, surface “tension-compression” deformation transformation and slope slip. The research results can provide a theoretical basis for the prevention and control of ground collapse in coal mining areas.

In order to study the surface movement and deformation law caused by the middle deep buried thick coal seam mining in northern Shaanxi Province, the first working face （112201 ｗｏｒｋｉｎｇ ｆａｃｅ） of Xiaobaodang Coal Mine which lies in the middle of the third phase planning area of Yushen Mining Area was taken as the research area. The surface movement and deformation characteristics, the movement deformation parameters and development laws of surface cracks caused by coal mining are obtained through the combination of observation station, GNSS observation station and theoretical analysis. The results show that: the maximum subsidence and the maximum subsidence coefficient were 3 840 mm and 0.66 respectively caused by mining of 112201 coal face. The duration of surface movement and deformation was about one and a half years. The start-up stage last 18 days, and the active stage last 110 days. Among the active stage, the surface movement and deformation are mainly concentrated in 43 days. The surface subsidence in the active stage was 91.4% of total subsidence value. The degree of development of surface crack induced by mining of 112201 coal face was weak. Relatively speaking, the development degree of surface cracks above the cut hole was greater than that above the trough, and the degree of the surface cracks above the goaf was weakest. The surface crack in the 112201 coal face was developed behind the mining position, and the width showed a “single peak” dynamic characteristic. There is coupling synchronization between the dynamic change characteristic and the velocity of surface subsidence.

The slope stability is a major concern to geotechnical engineers. Traditional methods of slope stability analysis have potentially ignored the influence of surface cracks. It is also known that seasonal rainfall and seepage through crack are closely related with slope failure. First, surface cracks provide special flow channels which increase the soil permeability and decrease the soil strength. Second, water-filled cracks apply an additional active force on the slope. Finally, cracks can create a part of the critical failure surface that has no shear strength. The objective of this paper is to investigate the influence of existing cracks on the stability of a cracked soil slope in different state. The effects of crack depth, slope angle and water-filled cracks on the stability of the cracked slope are explored. The analysis was conducted using the computer modelling programs Optum G2 to analysis of slope factor of safety. The results show that with increasing of slope angle the factor of safety decreases and this problem is significant in the slope with water filled cracks. Also, Factor of safety for all of slope angles in Dry and water filled cracks states with increasing the crack depth, decrease significantly.

Crack propagation under mixed-mode (I + II) conditions has been investigated in a semicircular disc where various levels of mixed-mode can be achieved by means of different geometry configurations. The research has been performed on a novel cementitious material, alkali-activated concrete. Its main advantage is thatit is environment-friendly. On the other hand, its fracture mechanical properties, as of yet, have not been described sufficiently. Therefore, a fracture analysis has been performed. The crack deflection under three-point bending conditions has been investigated numerically as well as experimentally. The numerical approach is based on a combination of the common finite element analysis and a multi-parameter form of the maximum tangential stress criterion. This generalized method is suitable especially for materials with specific (elasto-plastic, quasibrittle etc.) fracture behaviour. The over-deterministic method together with the Williams expansion is applied to approximate selected stress tensor components around the crack tip. In this work, the influence of the eccentric crack is also discussed. In the conclusions, several recommendations about using single-parameter/multi-parameter fracture mechanics are stated.

In order to ensure safe mining and reduce surface damage in shallow multi-seam mining, the failure characteristics of interburden strata with different coal pillars offset distances between pillars in the upper and lower seams, the distribution characteristics of stress concentration in coal pillars, and the development characteristics of stratum cracks and subsidence were investigated by physical and UDEC2D simulation. Meanwhile, the effect of different coal pillar offset distances on stress concentration of coal pillar and development of stratum cracks were studied. Based on those results, a formula for safe mining and reducing surface damage was established, which provided a theoretical basis for safe and environmentally friendly mining in shallow multi-seam. According to the results, the optimal coal pillar offset distance (the side to side horizontal distance of the upper and lower coal pillars) between the upper and lower coal seams was developed to reduce the stress concentration of coal pillars and surface damage. The results of this study have been applied in Ningtiaota coal mine and have achieved good results in safe and environmentally friendly mining.

We propose a new theoretical kinetic model of strength recovery by oxidation-induced self-healing of surface cracks in composites containing a healing agent (HA). The kinetics is a key parameter in the design of structural components that can self-heal the damage done in service. Based on three-dimensional (3D) observations of crack-gap filling, two crack-gap filling models, i.e., a bridging model and a tip-to-mouth filling model, are incorporated in the proposed kinetic model. These crack-gap filling models account for the microstructural features of the fracture surfaces, crack geometry, and oxidation kinetics of the healing-agent. Hence, the minimum and maximum remaining flaw sizes in the healed crack gaps are estimated for various healing temperatures, times, and oxygen partial pressure conditions. Further, the nonlinear elastic fracture mechanics suitable for small-sized remaining flaws, together with a statistical analysis of the original Weibull-type strength distribution, enables the prediction of upper and lower strength limits of the healed composites. Three sintered alumina matrix composites containing silicon carbide (SiC)-type HAs with various volume fractions and shapes, together with monolithic SiC ceramics, are considered. The strength of the healed-composite predicted by our model agrees well with the experimental values. This theoretical approach can be applied to HAs other than SiC and enables the design of self-healing ceramic components for various applications.

A beam blank is ideal for H-beam production, but there are more defects in/on beam blanks than other common blanks. The study of the H-beam blank quality assurance system has great significance for production to determine the key factors causing defects and optimise the casting process parameters. Experimental analysis and numerical simulation, based on an actual production process, were used as research methods. The former was used to test and analyse the cracks, inclusions, and the flux in the mould to determine the preliminary factors causing defects in a beam blank. The latter was used to simulate the flow and temperature fields and the movement of inclusions to determine the key factor leading to defects and to optimize the casting process parameters. Online implementation of the recommendations of this project was developed, which proved that it is very useful and efficient to control surface cracks on the web and enhance cleanliness of an H-beam blank.

As a revolutionary new technique, laser-engineered net shaping (LENS) is a layer additive manufacturing process that enables accurate, rapid and automatic repair of industrial component damage. In the laser repair (LR) process or in service, surface cracks can appear, which have a detrimental effect on the repair quality and the mechanical performance; therefore, the surface crack detection of repaired components has attracted much attention. Laser spot thermography is an important nondestructive testing method with the advantages of non-contact, full-field and high precision, which shows great potential in the crack detection of repaired components. The selection of thermographic process parameters and the optimization of thermal image processing algorithms are key to the success of the nondestructive detection. In this paper, the influence of material properties and thermographic process parameters on the surface temperature gradient is studied based on the simulation of laser spot thermal excitation, and the selection windows of thermographic process parameters for iron-based and nickel-based alloys are obtained, which is applied to the surface crack detection of repaired components. To improve the computational efficiency of thermal images, the Prewitt edge detection algorithm is used in the thermal image processing, which realized fast extraction of cracks with a high signal-to-noise ratio (SNR), and the detection sensitivity of crack width can reach 10 μm. To further study the influence of surface roughness on the thermographic detection, repair layers with and without polishing process are characterized, which show that the Prewitt edge detection algorithm is well applicable to crack detection on surfaces with different roughness level.

Economical design with sufficient fracture resistance is of high importance in any offshore pipeline projects. Using an Engineering Critical Assessment (ECA), alternate acceptance criteria for pipeline girth weld inspection can significantly reduce the cost of constructing of offshore oil and gas pipeline by minimizing unnecessary repairs. Offshore pipelines consist of short pipeline segments connected by girth welding method. Surface and embedded elliptical cracks due to welding operation are often observed at welding zone which pose a potential threat to the reliability of the offshore pipelines. To derive the acceptance criteria for pipeline girth weld defects and pipeline safety during installation and operation phase, an ECA based on fracture mechanics is required. In this paper, ECA of offshore pipeline with semi elliptical surface crack under pure tension loading is performed according to finite element method and BS7910 guideline. Moreover, a comparison between these two methods is offered. It is concluded that, ECA by BS7910 guideline is more conservative than finite element method, and the difference between the two diagrams increases as strain levels are increased. Also, comparisons of critical crack size curve for various strain levels are studied.

The detection of cracks is an important monitoring task in civil engineering infrastructure devoted to ensuring durability, structural safety, and integrity. It has been traditionally performed by visual inspection, and the measurement of crack width has been manually obtained with a crack-width comparator gauge (CWCG). Unfortunately, this technique is time-consuming, suffers from subjective judgement, and is error-prone due to the difficulty of ensuring a correct spatial measurement as the CWCG may not be correctly positioned in accordance with the crack orientation. Although algorithms for automatic crack detection have been developed, most of them have specifically focused on solving the segmentation problem through Deep Learning techniques failing to address the underlying problem: crack width evaluation, which is critical for the assessment of civil structures. This paper proposes a novel automated method for surface cracking width measurement based on digital image processing techniques. Our proposal consists of three stages: anisotropic smoothing, segmentation, and stabilized central points by k-means adjustment and allows the characterization of both crack width and curvature-related orientation. The method is validated by assessing the surface cracking of fiber-reinforced earthen construction materials. The preliminary results show that the proposal is robust, efficient, and highly accurate at estimating crack width in digital images. The method effectively discards false cracks and detects real ones as small as 0.15 mm width regardless of the lighting conditions.

The article presents the state of knowledge and research in the field of surface cracks occurring in disc braking systems of rail and car vehicles. The craze formed during the operation of vehicles is particularly dangerous and leads to breaking the disc into several pieces. It may lead to a loss of braking force and damage to the entire disc brake caliper. The main aim of the research is to identify surface cracks in brake discs made of cast iron and use experimental methods to estimate their depth. Research were conducted on the disc braking system developed by the authors. In examining the location and depth of cracks, the penetration method, ultrasound, as well as a special probe were used. This device measures the crack depth based on the electrical resistance between two points on the surface of the metallic object. The tests showed that the first microcracks on the brake discs appeared after 309 braking tests on the test stand. In addition, it was observed that the surface cracks length of the disc increased linearly to depth until they reached about 11.5–12 mm with corresponded to crack lengths in the range of 65–70 mm. However, determination of the regression functions presented in the article allows to estimate the depth of surface cracks up to 70 mm long on cast iron brake discs by measuring their length.

A new compression test fixture was designed in the present work to study the damage tolerance of composite laminates with surface cracks or notches. The compression failure behaviors of CCF300/5228A quasi-isotropic composite laminates with prefabricated surface cracks were studied experimentally. Through the size design of the test fixture and specimens and an application of a simple test method, the complex crack growth process was captured. The experimental results showed that the compression failure modes were mainly affected by crack angles and depths, and there were two typical failure modes, which were local intra- and inter-laminar damage propagating from the crack tips and delamination growth induced from the crack leading edge. This study verified the validity of the test fixture and test method, and revealed the compression failure mechanisms of composite laminates with surface cracks.

In this study, we present an online-monitoring approach using silver nanoparticle based ink on carbon fiber reinforced plastics (CFRP). After production of CFRP plates in a prepreg autoclave process and printing conductive paths on the material, we investigate the conductive paths of printed silver nanoparticle-based ink on CFRP by light microscopy. Mechanical tests with simultaneous electrical resistance measurements demonstrate the possibility to detect particular modes of failure with samples specifically designed to promote inter-fiber failures and delaminations under bending. Delaminations can be detected and localized inside the material by electrical through-thickness measurements and resistance measurements of the conductive paths allow for surface crack detection.

Aiming at the detection of concrete surface cracks, based on digital image processing technology, OTSU algorithm is processed based on differential image. First, the Gaussian filter is acted on the original image to obtain the smoothed image. Then the smoothed image is subtracted by the original image, the differential image is obtained. According to the OTSU algorithm, the optimal threshold on the differential image was calculated. As the characteristic cracks are a few pixels and with lower grey values, the pixels whose grey values are less than the mean value of the whole image to get the best threshold value were only calculated. Finally, remove the background noise based on the morphologic noise reduction to obtain the binary image of the crack. The experimental results show that the cracks can be discerned in complex backgrounds.

Offshore pipelines are an efficient long-distance transportation method for oil and gas. These are usually constructed by the use of girth welds, while welds may naturally contain flaws. Hence, it is essential to inspect the fracture response of girth welds in order to check the structural integrity of the pipeline. One of the guidelines that is using wide spread for investigating the fracture response of steel structures is BS 7910 which is based on Engineering Critical Assessment (ECA) method. In this paper Engineering Critical Assessment (ECA) of offshore pipeline girth welds is done according to BS 7910 through Crackwise software and the influence of several parameters on ECA is presented. It is concluded that Influence of misalignment on axial internal surface flaws is more significant than on axial external flaws. Furthermore it is observed that internal surface flaws have always larger values for tolerable defect heights than external surface cracks. In addition, circumferential surface flaws have evermore larger amount of acceptance level in defect heights than axial flaws.

In this work we present an application of InSAR and gravimetric surveys for risk management related to land subsidence and surface ground faulting generation. A subsidence velocity map derived from the 2007–2011 ALOS SAR imagery and a sediment thicknesses map obtained from the inversion of gravimetric data were integrated with a surface fault map to produce a subsidence hazard zoning in the city of Aguascalientes, Mexico. The resulting zoning is presented together with specific recommendations about geotechnical studies needed for further evaluation of surface faulting in these hazard zones. The derived zoning map consists in four zones including null hazard (stable terrain without subsidence), low hazard (areas prone to subsidence), medium hazard (zones with subsidence) and high hazard (zones with surface faulting). InSAR results displayed subsidence LOS velocities up to 10 cm/year and two subsidence areas unknown before this study. Gravimetric results revealed that the thicker sediment sequence is located toward north of Aguascalientes City reaching up to 600 m in thickness, which correspond to a high subsidence LOS velocity zone (up to 6 cm/year).

Multiaxial fatigue behavior is an important topic in critical structural components. In the present study the biaxial-planar fatigue behavior of a powder metallurgical TRIP steel (Transformation Induced Plasticity) was studied by taking into account martensitic phase transformation and crack growth behavior. Biaxial cyclic deformation tests were carried out on a servo hydraulic biaxial tension-compression test rig using cruciform specimens. Different states of strain were studied by varying the strain ratio between the axial strain amplitudes in the range of -1 (shear loading) to 1 (equibiaxial loading). The investigated loading conditions were proportional due to fixed directions of principal strains. The studied TRIP steel exhibits martensitic phase transformation from -austenite via ε-martensite into α‘- martensite which causes pronounced cyclic hardening. The α‘-martensite formation increased with increasing plastic strain amplitude. Shear loading promoted martensite formation and caused the highest α‘-martensite volume fractions at fatigue failure in comparison to uniaxial and other biaxial states of strain. Moreover, the fatigue lives of shear tests were higher than those of uniaxial and other biaxial tests. The von Mises equivalent strain hypothesis was found to be appropriate for uniaxial and biaxial fatigue, but too conservative for shear fatigue, according to literature for torsional fatigue. The COD strain amplitude which is based on crack opening displacement gave a better correlation of the investigated fatigue lives, especially those for shear loading. Different types of major cracks were observed on the sample surfaces after biaxial cyclic deformation by using electron monitoring in an electron beam universal system and scanning electron microscopy (SEM). Specimens with strain ratios of 1, 0.5, -0.1 and -0.5 showed mode I major cracks (perpendicular to the axis of maximum principal strain). Major cracks after shear fatigue had partially mode II orientation (tilted 45° to the loading axes) and afterwards bifurcated into two pairs of mode I cracks. Another shear test revealed a major crack of mode I orientation (parallel to the loading axes). These results are in good agreement to the literature. Micro cracks after shear fatigue were longer than those after biaxial fatigue with strain ratios of 1 and 0.5. Major and minor cracks after equibiaxial and shear loading showed crack branching and crack coalescence. The results on fatigue crack behavior support the assumption that the period of stage I (mode II) crack propagation is much longer under shear loading than under other biaxial conditions due to absence of tensile stress normal to the planes of maximum shear strain under shear loading

Die-casting dies are exposed to high thermal and mechanical loads. Thermal fatigue cracking of dies due to thermal cycling may importantly shorten the life-time of the die. Cracks degrade the surface quality of dies and consequently the surface of castings. In this study, thermal fatigue cracking of dies was analyzed during the process of die casting aluminium alloys. During the process cracks were observed and measured and their location and size were determined. Thermal and mechanical loads cause high local stresses and consequently surface cracks. First cracks occur as early as after 2000 cycles and propagate progressively with cycles.

Konya havzasını batıdan sınırlayan Konya fay zonunun doğusundaki Yazır fayı (YAF), toplam uzunluğu 10 km ye varan, kademeli olarak sıralanmış ve farklı uzunluklardaki bölümlerden oluşmuş bir faydır. KKD-GGB gidişli Yazır fayı (YAF), yörede yüzeyleyen Miyosen-Pliyosen yaşlı gölsel kireçtaşları ile Kuvaterner yaşlı karasal kırıntılılardan yapılı havza çökellerini kesmektedir. Konya merkeze bağlı Parsana ve Yazır mahalleleri arasındaki taş ocağı yarmalarında, YAF gölsel kireçtaşları ile havza çökellerini yan yana getirmiş ve bu faylanma ile gölsel kireçtaşları göreli olarak yükselirken, Kuvaterner yaşlı çökelleri çökmüştür. YAF, 3 km doğusundaki Çiftlikbaşı fayı ile, Konya havzası içinde üçgen geometrili küçük bir graben yapısı oluşturmuştur. Parsana ile Yazır mahalleri arasında YAF, yaklaşık düşeye yakın eğimli ve KKD-GGB yönelimlidir. Kayma çizikleri fayın çok az sağ yönlü doğrultu atıma sahip, düşeye yakın doğuya eğimli bir normal fay karakterinde olduğunu belgeler. Yüzey verilerine göre YAF, en az 25-30 m'lik bir düşey atıma sahiptir. YAF'nın hareketlerine bağlı olarak biri faya paralel, diğeri ise faya dik olarak yönlenmiş iki takım genişleme kökenli yapılar (ekstensiyonel yarıklar) oluşmuştur. Yaklaşık düşey konumlu yarıkların içi üstteki alüviyal çökeller tarafından doldurulmuştur. Düşey kesitlerinde aşağıya doğru kapanan üçgen geometrili yarıkların genişlikleri 15 cm – 2 m arasında değişmekte, boyları ise 10 m'ye kadar varabilmektedir. Yarıklar K10 D, 90 ve K80 B, 85 GB konumlarında yoğunlaşmıştır. Arazi gözlemleri, bu ekstensiyonel yapıların fayın Kuvaterner esnasında en az farklı iki evredeki hareketlerine bağlı olarak yüzey kırıkları şeklinde geliştiğini ve Konya havzasının söz konusu kesiminin, yaklaşık kuzey-güney ve doğu-batı gidişli birbirine dik iki yönelimde çekme gerilmelerinden etkilendiğini ortaya koymaktadır.

Konya havzasını batıdan sınırlayan Konya fay zonunun doğusundaki Yazır fayı (YAF), toplam uzunluğu 10 km ye varan, kademeli olarak sıralanmış ve farklı uzunluklardaki bölümlerden oluşmuş bir faydır. KKD-GGB gidişli Yazır fayı (YAF), yörede yüzeyleyen Miyosen-Pliyosen yaşlı gölsel kireçtaşları ile Kuvaterner yaşlı karasal kırıntılılardan yapılı havza çökellerini kesmektedir. Konya merkeze bağlı Parsana ve Yazır mahalleleri arasındaki taş ocağı yarmalarında, YAF gölsel kireçtaşları ile havza çökellerini yan yana getirmiş ve bu faylanma ile gölsel kireçtaşları göreli olarak yükselirken, Kuvaterner yaşlı çökelleri çökmüştür. YAF, 3 km doğusundaki Çiftlikbaşı fayı ile, Konya havzası içinde üçgen geometrili küçük bir graben yapısı oluşturmuştur. Parsana ile Yazır mahalleri arasında YAF, yaklaşık düşeye yakın eğimli ve KKD-GGB yönelimlidir. Kayma çizikleri fayın çok az sağ yönlü doğrultu atıma sahip, düşeye yakın doğuya eğimli bir normal fay karakterinde olduğunu belgeler. Yüzey verilerine göre YAF, en az 25-30 m'lik bir düşey atıma sahiptir. YAF'nın hareketlerine bağlı olarak biri faya paralel, diğeri ise faya dik olarak yönlenmiş iki takım genişleme kökenli yapılar (ekstensiyonel yarıklar) oluşmuştur. Yaklaşık düşey konumlu yarıkların içi üstteki alüviyal çökeller tarafından doldurulmuştur. Düşey kesitlerinde aşağıya doğru kapanan üçgen geometrili yarıkların genişlikleri 15 cm – 2 m arasında değişmekte, boyları ise 10 m'ye kadar varabilmektedir. Yarıklar K10 D, 90 ve K80 B, 85 GB konumlarında yoğunlaşmıştır. Arazi gözlemleri, bu ekstensiyonel yapıların fayın Kuvaterner esnasında en az farklı iki evredeki hareketlerine bağlı olarak yüzey kırıkları şeklinde geliştiğini ve Konya havzasının söz konusu kesiminin, yaklaşık kuzey-güney ve doğu-batı gidişli birbirine dik iki yönelimde çekme gerilmelerinden etkilendiğini ortaya koymaktadır.

Konya havzasını batıdan sınırlayan Konya fay zonunun doğusundaki Yazır fayı (YAF), toplam uzunluğu 10 km ye varan, kademeli olarak sıralanmış ve farklı uzunluklardaki bölümlerden oluşmuş bir faydır. KKD-GGB gidişli Yazır fayı (YAF), yörede yüzeyleyen Miyosen-Pliyosen yaşlı gölsel kireçtaşları ile Kuvaterner yaşlı karasal kırıntılılardan yapılı havza çökellerini kesmektedir. Konya merkeze bağlı Parsana ve Yazır mahalleleri arasındaki taş ocağı yarmalarında, YAF gölsel kireçtaşları ile havza çökellerini yan yana getirmiş ve bu faylanma ile gölsel kireçtaşları göreli olarak yükselirken, Kuvaterner yaşlı çökelleri çökmüştür. YAF, 3 km doğusundaki Çiftlikbaşı fayı ile, Konya havzası içinde üçgen geometrili küçük bir graben yapısı oluşturmuştur. Parsana ile Yazır mahalleri arasında YAF, yaklaşık düşeye yakın eğimli ve KKD-GGB yönelimlidir. Kayma çizikleri fayın çok az sağ yönlü doğrultu atıma sahip, düşeye yakın doğuya eğimli bir normal fay karakterinde olduğunu belgeler. Yüzey verilerine göre YAF, en az 25-30 m'lik bir düşey atıma sahiptir. YAF'nın hareketlerine bağlı olarak biri faya paralel, diğeri ise faya dik olarak yönlenmiş iki takım genişleme kökenli yapılar (ekstensiyonel yarıklar) oluşmuştur. Yaklaşık düşey konumlu yarıkların içi üstteki alüviyal çökeller tarafından doldurulmuştur. Düşey kesitlerinde aşağıya doğru kapanan üçgen geometrili yarıkların genişlikleri 15 cm – 2 m arasında değişmekte, boyları ise 10 m'ye kadar varabilmektedir. Yarıklar K10 D, 90 ve K80 B, 85 GB konumlarında yoğunlaşmıştır. Arazi gözlemleri, bu ekstensiyonel yapıların fayın Kuvaterner esnasında en az farklı iki evredeki hareketlerine bağlı olarak yüzey kırıkları şeklinde geliştiğini ve Konya havzasının söz konusu kesiminin, yaklaşık kuzey-güney ve doğu-batı gidişli birbirine dik iki yönelimde çekme gerilmelerinden etkilendiğini ortaya koymaktadır.

Konya havzasını batıdan sınırlayan Konya fay zonunun doğusundaki Yazır fayı (YAF), toplam uzunluğu 10 km ye varan, kademeli olarak sıralanmış ve farklı uzunluklardaki bölümlerden oluşmuş bir faydır. KKD-GGB gidişli Yazır fayı (YAF), yörede yüzeyleyen Miyosen-Pliyosen yaşlı gölsel kireçtaşları ile Kuvaterner yaşlı karasal kırıntılılardan yapılı havza çökellerini kesmektedir. Konya merkeze bağlı Parsana ve Yazır mahalleleri arasındaki taş ocağı yarmalarında, YAF gölsel kireçtaşları ile havza çökellerini yan yana getirmiş ve bu faylanma ile gölsel kireçtaşları göreli olarak yükselirken, Kuvaterner yaşlı çökelleri çökmüştür. YAF, 3 km doğusundaki Çiftlikbaşı fayı ile, Konya havzası içinde üçgen geometrili küçük bir graben yapısı oluşturmuştur. Parsana ile Yazır mahalleri arasında YAF, yaklaşık düşeye yakın eğimli ve KKD-GGB yönelimlidir. Kayma çizikleri fayın çok az sağ yönlü doğrultu atıma sahip, düşeye yakın doğuya eğimli bir normal fay karakterinde olduğunu belgeler. Yüzey verilerine göre YAF, en az 25-30 m'lik bir düşey atıma sahiptir. YAF'nın hareketlerine bağlı olarak biri faya paralel, diğeri ise faya dik olarak yönlenmiş iki takım genişleme kökenli yapılar (ekstensiyonel yarıklar) oluşmuştur. Yaklaşık düşey konumlu yarıkların içi üstteki alüviyal çökeller tarafından doldurulmuştur. Düşey kesitlerinde aşağıya doğru kapanan üçgen geometrili yarıkların genişlikleri 15 cm – 2 m arasında değişmekte, boyları ise 10 m'ye kadar varabilmektedir. Yarıklar K10 D, 90 ve K80 B, 85 GB konumlarında yoğunlaşmıştır. Arazi gözlemleri, bu ekstensiyonel yapıların fayın Kuvaterner esnasında en az farklı iki evredeki hareketlerine bağlı olarak yüzey kırıkları şeklinde geliştiğini ve Konya havzasının söz konusu kesiminin, yaklaşık kuzey-güney ve doğu-batı gidişli birbirine dik iki yönelimde çekme gerilmelerinden etkilendiğini ortaya koymaktadır.