Fracture Plane Research Articles

Study of temperature effect on hydrogen embrittlement in X70 pipeline steel

The study investigates the temperature effect on hydrogen embrittlement (HE) in X70 steel using Devanathan-Stachurski and tensile tests under varying cathodic hydrogen-charging currents. The most severe HE temperature threshold is identified via scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) methods. The temperature thresholds for 10 mA/cm2 and 20 mA/cm2 are 293 K and 283 K, respectively, while no critical temperature at 30 mA/cm2. The underlying mechanism is studied, and a predictive model is established. Also, the primary hydrogen-induced fracture plane is identified as {110}, beneath where hydrogen enhances plastic deformation in {110}<111> and inhibits in {112}<111>.

Dip effect on the orientation of rock failure plane under combined compression–shear loading

Shear failure often occurs in engineering rock mass (such as inclined pillar) in gently inclined strata. Prediction and characterization the orientation of shear failure plane is the foundation of rock mass engineering reinforcement. In this paper, sandstone samples are used to perform uniaxial and shear tests to obtain the basic mechanical parameters. Then, by employing the numerical method, the combined compression–shear loading tests were carried out for inclined specimens varied from 0° to 25° at an interval of 5°, to obtain the dip effect on the orientation of rock failure plane. The results show that the failure plane of rock changes with the change of dip angle of rock sample. Based on the Mohr–Coulomb criterion, the ultimate stress state of rock was characterized under combined compression–shear loading. The ultimate strength of rock is equal to the ratio of the stress circle radius of rock under combined compression–shear condition to the stress circle radius of rock under uniaxial compression condition, multiplied by the uniaxial compressive strength. The fracture angle of rock was defined under combined compression–shear loading. A theoretical model was developed for predicting the fracture angle. The developed model could be characterized by internal friction angle, dip angle of rock sample and Poisson's ratio. Finally, the numerical results of the fracture angle were analyzed, which are consistent with the predicted results of the model. The investigation shows that the rock fracture angle has a dip effect, which decreases with the increase of the inclination angle of the sample. The research results provide a new means to identify the potential failure plane of engineering rock mass, and lay a theoretical foundation for calculating the orientation of rock fracture plane.

Jake Seller Draw impact structure, Bighorn Basin, Wyoming, USA: The deepest known buried impact structure on Earth and its possible relation to the Wyoming crater field

We provide evidence demonstrating the impact origin of a structure, here named the Jake Seller Draw impact structure, which is buried below the Jake Seller Draw drainage basin, in the Bighorn Basin of Wyoming, western United States. The 4.3-km-diameter structure was first recognized as a seismic disturbance at a depth of ∼6.5 km in two- and three-dimensional seismic profiles. Microstructural analysis of drill cuttings situated in the center and outside of Jake Seller Draw revealed the presence of multiple sets of planar deformation features and planar fractures in nine quartz grains, thereby confirming the hypervelocity impact origin of the structure. The seismic data show that Jake Seller Draw is a complex impact structure containing a 1-km-wide central uplift. The geologic and seismic data suggest that Jake Seller Draw is the most deeply buried impact structure known on Earth to date. The stratigraphic framework suggests that the crater was formed in a nearshore environment at the Pennsylvanian−Permian boundary, ∼280 m.y. ago. This age coincides with the age of the Wyoming crater field 300 km southeast of Jake Seller Draw and may suggest a common origin.

A Two-Dimensional Planar Fracture Network Model for Broken Rock Mass Based on Packer Test and Fractal Dimension

Broken rock masses with the complexity and concealment widely exist in nature such as underground mine, collapse column, and zone. It is extremely difficult to model fracture networks and to simulate water diffusion for broken rock masses. To explore a reasonable fracture network model for broken rock masses, a new method for modeling a two-dimensional planar fracture network model is proposed in this paper. It includes packer test, empirical relationship, fractal width description, and symmetric expansion modeling. Then, the fluid-solid coupling is used to simulate the diffusion properties of water in the two-dimensional planar fracture network model. It is found that the diffusion velocities vmax and vmin do not appear in the fracture widths λmax and λmin. It indicates that the fracture widths λmax and λmin in the fracture network model for broken rock mass have little impact on the diffusion velocity. Furthermore, the fracture distribution pattern in the fracture network model is an important factor affecting the diffusion velocities vmax and vmin. The simulation results of water diffusion in the currently proposed model are almost consistent with the actual process of the packer test. Also, the validity of the two-dimensional planar fracture network model is verified by comparing the simulation results with the existing research.

High-resolution source imaging and moment tensor estimation of acoustic emissions during brittle creep of basalt undergoing carbonation

SUMMARY As the high-frequency analogue to field-scale earthquakes, acoustic emissions (AEs) provide a valuable complement to study rock deformation mechanisms. During the load-stepping creep experiments with CO2-saturated water injection into a basaltic sample from Carbfix site in Iceland, 8791 AE events are detected by at least one of the seven piezoelectric sensors. Here, we apply a cross-correlation-based source imaging method, called geometric-mean reverse-time migration (GmRTM) to locate those AE events. Besides the attractive picking-free feature shared with other waveform-based methods (e.g. time-reversal imaging), GmRTM is advantageous in generating high-resolution source images with reduced imaging artefacts, especially for experiments with relatively sparse receivers. In general, the imaged AE locations are found to be scattered across the sample, suggesting a complicated fracture network rather than a well-defined major shear fracture plane, in agreement with X-ray computed tomography imaging results after retrieval of samples from the deformation apparatus. Clustering the events in space and time using the nearest-neighbour approach revealed a group of ‘repeaters’, which are spatially co-located over an elongated period of time and likely indicate crack, or shear band growth. Furthermore, we select 2196 AE events with high signal-to-noise-ratio (SNR) and conduct moment tensor estimation using the adjoint (backpropagated) strain tensor fields at the locations of AE sources. The resulting AE locations and focal mechanisms support our previously assertion that creep of basalt at the experimental conditions is accommodated dominantly by distributed microcracking.

An ICME framework for short fiber reinforced ceramic matrix composites via direct ink writing

A manufacturing-driven ICME framework is proposed to model short fiber reinforced ceramic matrix composites (CMCs) via direct ink writing. Currently, there lacks efforts to investigate the effects of properties of short fiber reinforced CMCs due to fiber alignment variance. A multi-scale modeling approach is presented to use representative volume elements to capture the homogenized mechanical behavior at various fiber aspect ratios and volume ratios. The orthotropic material properties are mapped to model the printing process. A series of tensile tests simulations show that with 20∘ standard deviation in fiber alignment, the fracture plane has the maximum local tensile stress range at a printing angle of 30∘ and has the minimum local tensile stress range at 90 ∘ . When the standard deviation increases from 20∘ to 40∘, the average tensile strength across the fracture plane decreases by 2%, but the stress variations increase 27.6%.

ХАРАКТЕРИСТИКА ПОВРЕЖДЕНИЙ МАЛОБЕРЦОВОЙ КОСТИ ПРИ ПЕРЕЛОМАХ ЛОДЫЖЕК И ДИСТАЛЬНОГО ОТДЕЛА ГОЛЕНИ

The study purpose was the evaluation of fibula injuries in malleolar fractures and distal tibia fractures (segments 44 and 43 according to AO/OTA fracture classification), to reveal the most typical types of injuries and morphological fracture parameters, which could be important for the development of the intramedullary fixator of the fibula. Radiological data of 57 patients with malleolar fractures and 54 patients with distal tibia fractures were evaluated. In ankle injuries the vast majority of fibula fractures (84.2%) were presented by transsyndesmotic injuries (type B according to AO/OTA), majority of fibula fractures (89%) were simple, without signs of comminution, the fracture plane passed at an angle of 33.1°±10.7° to the axis of the fibula, the center of fracture was located at the level of 21.6±8.8 mm from ankle articular surface. In distal tibia fractures fibula injuries were more variable: in 20% of cases there were no fibula fracture at all, 6% involved the proximal part, 27% - shaft and 47% distal part of the fibula. Comminuted fractures were seen in 32% of cases, the center of the fracture was located from 10 mm distal to the tibia articular surface to 317 mm proximal to it (Ме 35 mm, Q1-Q3: 15-68 mm). The revealed data shows that most important for the development of the intramedullary fibular fixator are ankle injuries, which have more predictable pattern.

Dravite of Terny Meteoritic Crater (Kryvyi Rih District)

During mineralogical investigations of breccia and volcanic rocks of the Terny structure (Veseli Terny, Kryvyi Rih), so-called Terny meteoritic crater, the mineral tourmaline, previously unknown here, was found. Tourmaline crystals, with a length from 0.05 to 1.0 mm and more and up to 0.1—0.2 mm wide, are associated with quartz, potassium feldspar, graphite and apatite. The morphology and chemical composition of tourmaline were examined using optical microscope and EPMA in transparent thin sections. The tourmaline crystals are unusually parted along two transverse systems of microcracks oriented obliquely to the prism faces. EPMA reveals that tourmaline is dravite. The specific deformations of dravite and observed mineral associations probably indicate the rock formation under conditions of high pressures and temperatures of impact metamorphism. It is also confirmed by the presence of planar fractures in quartz.

Modelling and inferring fracture curvature from borehole GPR data: A case study from the Bedretto Laboratory, Switzerland

AbstractFracture curvature has been observed from the millimetre to the kilometre scales. Nevertheless, characterizing curvature remains challenging due to data sparsity and geometric ambiguities. As a result, most numerical models often assume planar fractures to ease computations. To address this limitation, we present a novel approach for inferring fracture geometry from travel‐time data of electromagnetic or seismic waves. Our model utilizes co‐kriging interpolation of control points in a three‐dimensional surface mesh to simulate fracture curvature effectively, resulting in an unstructured triangular grid. We then refine the fracture surface into a structured grid with equidistant elements so that both small‐scale heterogeneities and large‐scale curvature can be modelled. To constrain the fracture geometry, we perform a deterministic travel‐time inversion to optimally place these control points. We validate our methodology with synthetic data and address its limitations. Finally, we infer the geometry of a large (more than 200 m) fracture observed in single‐hole ground‐penetrating radar field data. The fracture surface closely agrees with borehole televiewer observations and is also constrained far from the boreholes. Our modelling approach can be trivially adapted to multi‐offset ground‐penetrating radar or active seismic data.

Temporal constraints on hydrothermal circulation associated with strike-slip faulting in the Permian Maokou carbonates, central Sichuan Basin (SW China)

Despite the ubiquity of hydrothermal fluid circulation in the crust, its timing is difficult to precisely determine using traditional thermometric dating due to strongly disturbed geothermal fields. We present a case study from the mid-Permian hydrocarbon-bearing dolostone reservoirs, situated proximally to strike-slip faults in the central Sichuan Basin (China), to highlight the utility of carbonate in-situ U-Pb geochronology in delineating the timing of hydrothermal fluid flow. Matrix and void-filling cement dolomite phases were identified in the porous Maokou Formation carbonates. Predominantly manifesting as saddle dolomites along fractures, these cements yielded statistically homogeneous U-Pb ages (242.5 ± 3.1 Ma, 238.9 ± 8.2 Ma, 244 ± 15 Ma, and 239.2 ± 6.5 Ma), slightly postdating the established stratigraphic timeline (ca. 273 to 259 Ma). The narrow temporal span suggests early emplacement following a short burial, compatible with the petrographic observation of burial stylolites crosscutting saddle dolomites. Integrating shallow emplacement depths inferred from a comparison between the dolomite U-Pb ages and a published burial history, with fluid-inclusion microthermometry, elucidates the hydrothermal system that was once present in this field. The pervasive occurrence of hydrofracturing, along with dolomite geochemical indicators represented by bell-shaped (REE + Y) PAAS patterns and elevated Y/Ho ratios, provide additional evidence for the hydrothermal fluid injection and resulting dolomitization. The dolomites' positive Eu anomalies and the parent fluids’ 18O enrichment indicate a source from deeper basinal pore waters that have interacted significantly with ambient rocks. The overlying Triassic evaporites may have provided Mg-rich brines, mixing into the circulating hot fluids responsible for hydrothermal dolomitization. Our dolomite U-Pb ages coincide with the seismically estimated timing of transtensional strike-slip fault activation. This temporal correspondence, combined with spatial associations and lateral slickensides along fracture planes, suggests that the hydrothermal fluid movement is highly relevant to the active strike-slip faults. This observation reveals a previously unrecognized early-middle Triassic, structurally controlled hydrothermal activity in the region. We propose that this episode of hydrothermal circulation was driven by extensional tectonism in response to the spreading of the Proto-Tethys Ocean. This finding is not in line with the earlier research that considered late Permian Emeishan volcanism to have been the main trigger for hydrothermal fluid influx. The long-standing view regarding hydrothermal dolomitization in this region may need to be re-evaluated.

Logoisk impact structure, Belarus: Shock transformation of zircon

AbstractThe 17 km diameter, 30 Ma old Logoisk structure in Belarus (54°12′ N, 27°48′ E) was intensively drilled within the crater area. We summarize geological structure and petrologic information previously published mostly in Russian and describe shock deformation of zircon for the first time. The shock deformation features of zircon in the Logoisk suevite include the transition to reidite, the formation of planar fractures and granular textures, and the thermal decomposition to ZrO2 and SiO2. The presence of reidite in two grains in suevite was confirmed by micro‐Raman spectroscopy and EBSD (electron backscattered diffraction). Reidite was found in suevite glass of the Logoisk structure in grains containing zircon and in the ZrO2‐enriched rims on zircon. Granular zircon is commonly associated with ZrO2 and occurs as rims on zircon with interstitial impact melt, as dendritic rims, and in the inner parts of a zircon grain. A granular zircon from Logoisk represents the highest documented temperature of zircon transformation. The new data expands the knowledge of the P‐T conditions of formation of the Logoisk structure.

Characterization of Failure Behavior in Unidirectional Fiber-Reinforced Polymer via Off-Axis Compression on Small Block Specimens.

An experimental investigation was focused on the failure behavior of unidirectional fiber-reinforced polymers when subjected to combined longitudinal/transverse compression and in-plane shear due to off-axis loading. Block-shaped and end-loaded specimens, spanning ten different fiber orientations (0°, 5°, 10°, 15°, 20°, 30°, 45°, 60°, 75°, and 90° with respect to the loading direction), were loaded to ultimate failure using a dedicated fixture. Different failure modes, including longitudinal compression, in-plane shear, and transverse compression, were identified, along with distinctive characteristics of the corresponding failure envelopes. Four physically based failure theories-Hashin, Camanho, Puck, and LaRC05-were subjected to a comparative analysis. Criteria derived from the concept of the action plane consistently outperformed in describing matrix-dominated failures, providing both qualitative and quantitative predictions of failure stresses and fracture plane orientation. However, for fiber-dominated failures, these theories seem to fall short in providing satisfactory predictions, particularly in accurately describing the influence of shear on fiber compression failure. Although criteria based on fiber-kinking theory can reasonably explain the formation of kink bands, they tend to yield overly conservative results. Recalibrations and minor refinement based on experimental results were implemented, leading to an improved agreement. Finally, the constructive role of off-axis compression tests in characterizing the failure behavior of unidirectional composites is discussed.

A progressive damage model associated with dynamic fracture toughness and IFF criterion with a fast search algorithm of fracture angle

This paper presents a quick search algorithm of the fracture angle of inter-fiber fracture (IFF) criterion and a progressive damage model considering the dynamic fracture toughness effect. The fracture angle determination of the IFF criterion is necessary and time-consuming, which has limited its practicality. Therefore, to accurately calculate stress exposure factors under various combinations of stress states, a highly efficient algorithm is needed. In this paper, a novel algorithm using stress tractions on the fracture plane and the golden section search (GSS) is promoted. Through a series of simulation tests, this novel algorithm has been proven to be exact and efficient compared with other two common algorithms, which saves an average of 63.2 % and 28.1 % of the time in 1 million calculations and 2 h 2 min 4 sec and 39 min 2 sec in simulations. Additionally, fracture toughness, which controls material damage evolution process, also has strain-rate effect like elastic modulus and strength. Hence, a new progressive damage model considering the dynamic fracture toughness effect is proposed. The results of dynamic compression and ballistic impact tests and simulations demonstrate the fidelity of the novel damage model.

Imaging Patterns of Temporal Bone Fracture among Patients with Head Injury at Tikur Anbessa Specialized Hospital, Ethiopia.

Temporal bone fracture is usually a sequel of significant blunt head injury. Fracture of the temporal bone is mainly classified according to the orientation of the fracture plane and whether there is involvement of the otic capsule. Despite its frequent occurrence, there is limited research on the frequency and pattern of temporal bone fractures in our setup. Retrospective cross-sectional hospital - based study of 60 patients who underwent computed tomography of the head for head trauma at Tikur Anbessa Specialized Hospital during the study period from October 2020 - October 2022. Among the 60 patients enrolled in the study, the mean age of presentation was 31.1 years with a male-to-female ratio of 4:1. There were 69 temporal bone fractures, 9(15%) were bilateral and 51(85%) unilateral The longitudinal fracture pattern was the most common fracture pattern, occurring in 40(78.4%) of unilateral cases, 15(83.3%) of bilateral cases. Otic capsule sparing fractures accounted for 49(96.07%) of unilateral fracture cases, and all patients with bilateral involvement had an otic capsule sparing fracture. Among the 42 patients for whom data regarding post-traumatic hearing outcome was available, 4 patients had post-traumatic hearing impairment. Anatomically, the squamous portion of the temporal bone was involved in 30(43.5%) of cases. Fractures affecting the squamous portion of the temporal bone, longitudinal fracture patterns, and otic capsule sparing were the most frequent forms. The majority of temporal bone fractures were associated with other bone fractures and intracranial injuries.

24% Single‐Junction GaAs Solar Cell Grown Directly on Growth‐Planarized Facets Using Hydride Vapor Phase Epitaxy

AbstractA 24%‐efficient single‐junction GaAs solar cell grown directly on a faceted, spalled (100) GaAs substrate after in situ planarization growth by hydride vapor phase epitaxy (HVPE) is achieved. Controlled spalling, a promising low‐cost substrate reuse technique, produces large facets in (100)‐oriented GaAs substrates due to the orientation of the fracture planes used for lift‐off. Planarization by HVPE offers a path toward direct use of these spalled substrates without costly polishing steps. Here, the growth rate anisotropy enabling planarization arising from diffusion and differences in the adsorption of growth species on {n11}B‐type facets relative to (100) is determined. Consecutive planarization and device growth that results in a solar cell with a minimal performance difference relative to a control cell grown on an epitaxy‐ready substrate are demonstrated. These results show that controlled spalling coupled with HVPE planarization is a viable pathway for lowering the cost of III‐V photovoltaics.

Predictive factors of distal radioulnar joint instability after surgical treatment of distal radius fractures.

Distal radioulnar joint (DRUJ) instability is a common postoperative complication of distal radius fractures, seriously impacting patients' quality of life. This study investigated its possible influencing factors to determine prognosis and to guide treatment better. We retrospectively included a series of patients with distal radius fractures that underwent volar locking plate fixation. Basic patient information and imaging parameters were collected. The incidence of DRUJ instability during follow-up was recorded, and factors associated with DRUJ instability were determined using univariate analysis and multifactorial logistic regression analysis. A total of 159 patients were enrolled in this study. At 6 months of follow-up, 54 patients (34.0%) had DRUJ instability, and multivariate analysis showed coronal plane displacement (OR, 1.665; 95% CI, 1.091-2.541), fracture classification (OR, 0.679; 95% CI, 0.468-0.984) and DRUJ interval (OR, 1.960; 95% CI, 1.276-3.010) were associated with DRUJ instability after volar locking plate. DRUJ interval, coronal plane displacement, and fracture classification are associated with DRUJ instability during follow-up. Therefore, preoperative risk communication and intraoperative attention to recovering relevant imaging parameters are necessary for these patients.

Investigation of morphological effects on crushing characteristics of calcareous sand particle by 3D image analysis with spherical harmonics

Morphological effects on crushing characteristics of single calcareous sand particle were investigated experimentally. Before test, 3D images of 287 bulky particles with size range of 2.5–5.5 mm were captured using computed tomography scan, and outer and inner morphologies (i.e., size, sphericity, angularity and intra-particle void ratio) were extracted by image analysis with spherical harmonics. Then, uniaxial compression test was performed on individual particle to attain crushing characteristics (i.e., crushing strength, displacement, mode and fragment distribution). Normalized crushing displacement is found insensitive to particle morphologies. Crushing strength is positively correlated to sphericity, and negatively correlated to angularity and intra-particle void ratio. Particularly, crushing strength with intra-particle void ratio >4% is almost half of that lower than 4%. Fragments exhibits a mixed size distribution of large remnants and fines generated from contact damage and fracture plane. All test data can move towards a morphology-related upscaling model for calcareous sand crushing.

Fracture behaviour of transversely isotropic rocks under pure mode III fracture: Experiment and numerical simulation

The fracture behaviour in transversely isotropic rocks is significantly affected by stratification planes. In this paper, experimental tests were carried out using edge-notched disc bending (ENDB) specimens with different stratification plane inclination angles to investigate the fracture characteristics of transversely isotropic rocks under pure mode III loading. The influence of stratification plane inclination fracture toughness and fracture pattern were also analysed. An effective numerical model for ENDB specimens was established to simulate and analyse the microscale fracture process under pure mode III loading in PFC3D, and flat-joint contact (FJC) and smooth-joint contact (SJC) were used to simulate the rock matrix and stratification, respectively. The simulation results showed that the fracture plane development trend of specimens with different inclinations is different. For the specimens with stratification plane inclinations of 0°, 15°, 75° and 90°, the cracks at both ends of the prefabricated notch develop symmetrically. However, for specimens with inclinations of 30° and 60°, the propagation behaviour along the stratification plane occurs prior to cutting the stratification planes. In addition, higher stratification plane strength and wider spacing lead to higher peak loads. The fracture trajectory extends along the stratification plane more obviously with the decrease in the stratification plane strength, and the development degree of the fracture trajectory along the stratification plane decreases with the decrease in the stratification plane spacing.

Mode-{I, III} multiaxial fatigue of welded joints in steel maritime structures: Effective notch stress based resistance incorporating strength and mechanism contributions

The response of maritime structures can be multiaxial, involving predominant mode-I and non-negligible mode-III components. Adopting a stress distribution formulation based effective notch stress as fatigue strength parameter for mixed mode-{I, III} multiaxial fatigue assessment purposes, a mode-I equivalent von Mises type of failure criterion has been established at the critical fracture plane. Counting includes a cycle-by-cycle non-proportionality measure and damage accumulation is based on a linear model. Distinguished mode specific and material characteristic strength and mechanism contributions in terms of respectively the resistance curve intercept and mean stress induced response ratio coefficient, resistance curve slope and material characteristic length, have been incorporated. Evaluating the mid-cycle fatigue resistance, the outperformance is impressive. The analysed multiaxial mode-{I, III} data fits the uniaxial mode-I reference data scatter band and a single resistance curve can be used for fatigue assessment.

Biomechanics of internal fixation in Hoffa fractures – A comparison of four different constructs

ObjectiveCompare the biomechanical effectiveness of four different bone-implant constructs in preventing fracture displacement under axial loading. MethodsTwenty artificial femora had a standardized coronally oriented fracture of the lateral femoral condyle, representing a Hoffa fracture classified as a Letenneur type I. Four different fixation constructs were applied to the synthetic bones for biomechanical testing. The constructs consisted of a posterolateral (PL) buttressing locking plate in conjunction with two cannulated lag screws inserted from posterior to anterior (PA) – Group 1; Two cannulated screws inserted from anterior to posterior (AP) without plating– Group 2; A posterolateral (PL) buttressing locking plate in isolation – Group 3; and a combination of two lag screws from anterior to posterior (AP) in addition to a horizontal one-third tubular locking plate – Group 4. An axial load was applied to the fracture site with a constant displacement speed of 20 mm/min, and the test was interrupted when a secondary displacement was detected determining a fixation failure. We recorded the maximum applied force and the maximum fracture displacement values. ResultsGroup 1 demonstrated the highest overall bone-implant axial stiffness with the lowest secondary displacement under loading. Groups 3 and 4 showed equivalent mechanical behavior. Group 2 presented the lowest mechanical stiffness to axial loading. The combination of the one-third tubular locking plate with anterior-to-posterior lag screws (Group 4) resulted in 302 % increase in fixation stiffness when compared to anterior-to-posterior lag screws only (Group 2). ConclusionsThis study confirms the mechanical superiority of having a plate applied parallel to the main fracture plane in the setting of coronally oriented femoral condyle fractures. The addition of a horizontal plate, perpendicular to the main fracture plane, significantly increased the resistance to shearing forces at the fracture site when compared to constructs adopting just cannulated screws. Level of evidenceBiomechanical study