Orientation Distribution Research Articles

Fracture simulation of fiber reinforced composite panels with holes

Fiber reinforced composite (FRC) with holes have broad applications in various fields. In this study, the influence of fiber orientation and hole distribution on the fracture behavior of FRC was investigated. A phase-field modeling was established to simulate the fracture process of the composite, and the mechanical performance of unidirectional fiber reinforced composite and woven fiber reinforced composite were analyzed, respectively. Our numerical results showed that fiber orientation and hole distribution have a significant impact on the fracture behavior of FRC. We observed that aligning the fibers parallel to the loading direction led to an increase in the maximum load bearing capacity of the composite. A more uniform hole distribution can enhance the overall mechanical performance of FRC. Furthermore, in the presence of thermal shock, crack propagation tends to grow towards the hole. These findings are of great significance for understanding the fracture behavior of FRC, and for optimizing material design and fabrication processes.

Rapid reversion of martensite in low-alloy steel under electropulsing treatment: Exploring feasibility of reversible transformation

Reversibility is an essential feature of martensitic transformation but is always believed impossible in FeC alloys since martensite (α') is unstable, which decomposes and forms cementite (θ) before reversion begins. Here we used electropulsing treatment (EPT) to inhibit θ precipitation and explored the feasibility of reversible transformation without α' decomposition in low-alloy steels (22MnB5 and 35CrMo steels). The reversion behaviors of the electropulsed specimens were analyzed by morphology, orientation, elemental distribution, and final microstructure. The result shows that in low carbon, low-alloy steel (22MnB5 steel), acicular γ abruptly grows through the whole pack without composition change. The prior γ grains are reproduced with the same grain size, shape, and orientation, indicating that inhibiting the θ precipitation does make steels with low carbon content achieve the reversibility of martensitic transformation. This phenomenon mainly results from reducing the effective driving force for θ precipitation by the current. However, in low-alloy steel with higher carbon content (35CrMo steel), 3D orientation distributions reveal that the prior γ grain is divided into equiaxed grains with various orientations and irregular grains with slightly changed orientations. This result suggests that when carbon content increases above a limit, high dislocation densities lead to recrystallization and destroy the original orientation relationship.

Orientation engineering of magnesium alloy: A review

Mg and its alloys have garnered significant attention due to their exceptional properties, including low density, good damping capacity, biocompatibility, recyclability, and high hydrogen storage capacity. These attributes position them as promising materials for applications in aerospace, transportation, electronics, and biomedical. The wrought Mg alloys, particularly in sheet form, are important materials for manufacturing lightweight structural components. However, their application is often constrained by relatively low room temperature formability. Preferred orientation, also known as texture, plays a crucial role in determining the plasticity and formability of Mg alloys. In this paper, we propose the concept of “orientation engineering”, which involves controlling the crystallographic orientation, thereby enhancing the plasticity and formability of Mg alloys. This review addresses two main aspects: firstly, it systematically explores how preferred orientation influences the plasticity and formability of Mg alloys, providing a foundation for orientation engineering. Secondly, it comprehensively introduces the development of methods to control grain orientation distribution, including alloying, pre-deformation, and asymmetric processing. This review might enhance the scientific understanding of orientation modification in Mg alloys and offer valuable guidance for future research on high-formability Mg alloys.

Artificial intelligence-aided semi-automatic joint trace detection from textured three-dimensional models of rock mass

It is of great importance to obtain precise trace data, as traces are frequently the sole visible and measurable parameter in most outcrops. The manual recognition and detection of traces on high-resolution three-dimensional (3D) models are relatively straightforward but time-consuming. One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces. In this study, a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured three-dimensional (3D) model. A virtual digital image rendering was then employed to capture virtual images of selected regions. This technique helps to overcome limitations caused by the surface morphology of the rock mass, such as restricted access, lighting conditions, and shading effects. After AI-powered trace detection on two-dimensional (2D) images, a 3D data structuring technique was applied to the selected trace pixels. In the 3D data structuring, the trace data were structured through 2D thinning, 3D reprojection, clustering, segmentation, and segment linking. Finally, the linked segments were exported as 3D polylines, with each polyline in the output corresponding to a trace. The efficacy of the proposed method was assessed using a 3D model of a real-world case study, which was used to compare the results of artificial intelligence (AI)-aided and human intelligence trace detection. Rosette diagrams, which visualize the distribution of trace orientations, confirmed the high similarity between the automatically and manually generated trace maps. In conclusion, the proposed semi-automatic method was easy to use, fast, and accurate in detecting the dominant jointing system of the rock mass.

Application of Microseismic Monitoring in Fracturing Process Evaluation

Abstract Fracture-mesh control technologies, such as modified liquid system (controlled fracture technology), pulse fracturing reform and directional perforation technology, have been adopted in the large-scale fracturing process of well Qaiping 1 in Qaidam Basin. However, whether the technology has achieved the predetermined goal needs to be verified. In order to fully grasp the fracture morphology in each stage of fracturing construction, the underground microseismic fracture monitoring technology is used to reveal the fracture length, height, width, orientation and spatial distribution characteristics. Based on the analysis of monitoring results, the following conclusions are obtained. (1) The collection of microseismic event data plays a key role in interpreting the properties of fractures, so as to more accurately understand and predict the formation and development of fractures. (2) Real-time microseismic monitoring reveals the application value of a variety of special processes in the formation reconstruction effect, and the transformation of liquid system (controlled fracture process), pulse fracturing and directional perforating process have significant effects on fracture morphology.

Stress evolution in rocks around tunnel under uniaxial loading: Insights from PFC3D-GBM modelling and force chain analysis

In underground engineerings, the evolution of the stress state in the surrounding rocks can effectively reveal its fracture mechanism. To precisely describe this microscopic information, the present study utilizes the three-dimensional Grain-based model based on Particle Flow Code (PFC3D-GBM) to construct a square numerical specimen with a pre-existing hole representing a tunnel and subjected it to uniaxial loading. In this model, different types of mineral structures and internal force chain networks are distinguished at a three-dimensional scale. Furthermore, the evolution of force chain networks in the top, bottom, left and right regions around the tunnel is quantitatively characterized. The anti-fracture capability depending on stress state of various structures is calculated and then the fracture mechanism from the point of anti-fracture capability is discussed. The research results indicate that at at the beginning of loading, some red force chains with higher level have appeared on both sides of the tunnel. As the load goes on, red force chain network extending from both sides of the tunnel to the upper and lower ends of the specimen have emerged. The average value and sum value of all force chains show an increasing trend before the peak load and a decreasing trend after the peak load. The average value of force chains within a specific structure can accurately reflect the microscopic mechanical properties of that structure. The average values of force chains on the left and right sides of the tunnel are higher, both in terms of starting points and ascending rates, than those in the upper and lower regions of the tunnel. The orientation distribution of all force chains is relatively uniform, but force chains with higher level are generally align with the loading direction. The fundamental reason for the high degree of fragmentation on the left and right sides of the tunnel is that these regions bear more external load than the upper and lower regions, rather than being inherently more prone to fracture.

Centrifugal Inertia-Induced Directional Alignment of AgNW Network for Preparing Transparent Electromagnetic Interference Shielding Films with Joule Heating Ability.

Transparent electromagnetic interference (EMI) shielding is highly desired in specific visual scenes, but the challenge remains in balancing their EMI shielding effectiveness (SE) and optical transmittance. Herein, this study proposed a directionally aligned silver nanowire (AgNW) network construction strategy to address the requirement of high EMI SE and satisfactory light transmittance using a rotation spraying technique. The orientation distribution of AgNW is induced by centrifugal inertia force generated by a high-speed rotating roller, which overcomes the issue of high contact resistance in random networks and achieves high conductivity even at low AgNW network density. Thus, the obtained transparent conductive film achieved a high light transmittance of 72.9% combined with a low sheet resistance of 4.5 Ω sq-1 and a desirable EMI SE value of 35.2dB at X band, 38.9dB in the K-band, with the highest SE of 43.4dB at 20.4GHz. Simultaneously, the excellent conductivity endowed the film with outstanding Joule heating performance and defogging/deicing ability, ensuring the visual transparency of windows when shielding electromagnetic waves. Hence, this research presents a highly effective strategy for constructing an aligned AgNW network, offering a promising solution for enhancing the performance of optical-electronic devices.

The Changing Morphology of Global Precipitation Systems during the Last Two Decades

Abstract The morphology of global precipitation systems can enhance our comprehension of precipitation patterns and the underlying physical processes. However, several unresolved issues remain in the existing studies of precipitation system morphology. This study employs Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) (IMERG)-derived precipitation system dataset to investigate the climatological and changing characteristics of global precipitation system morphology from 2001 to 2022. The results show that precipitation systems with larger scales tend to be more flattened in morphology, while no clear differences in morphological characteristics are observed across systems with different intensities. In terms of geographic distributions, a notable land–sea contrast is observed, with land systems more circular than those over oceans. Due to the impact of the Coriolis force, the orientation distribution of precipitation systems shows obvious hemispherical contrast. Precipitation systems over tropical regions are more regular in shape and more likely to be organized convective systems. During the period of 2001–22, there is a significant trend of global precipitation systems becoming more flattened and are more likely to manifest as organized convective systems. Our results also indicate that the precipitation system morphology is under combined influence of subtropical highs, lateral stretching influences of wind, and the organizing effects of moisture transport and convergence. Moreover, the increasing flattening of precipitation systems could be attributed to enhanced atmospheric stability which constrains vertical expansion and increased moisture availability which favors wider horizontal extension. This study could provide new insights into precipitation changes under global warming.

Evaluating the efficacy of uniformly designed square mesh resin 3D printed scaffolds in directing the orientation of electrospun PCL nanofibers

Replicating the architecture of extracellular matrices (ECM) is crucial in tissue engineering to support tissues’ natural structure and functionality. The ECM’s structure plays a significant role in directing cell alignment. Electrospinning is an effective technique for fabricating nanofibrous substrates that mimic the architecture of extracellular matrices (ECM). This study aims to evaluate the efficacy of resin 3D-printed scaffolds made from a low-conductivity material (i.e., a resin composed of methacrylated oligomers, monomers, and photoinitiators) in directing the alignment of electrospun polycaprolactone (PCL) nanofibers. Six 3D-printed scaffolds were fabricated using stereolithography (SLA) technology and strategically positioned on an aluminum foil collector plate during electrospinning. The structured geometry of the scaffolds, rather than the local electric field distribution, is hypothesized to guide nanofiber alignment. Images acquired through the scanning electron microscopy (SEM) were used to analyze and statistically quantify the nanofibrous scaffolds to evaluate the alignment of nanofibers over the scaffolds compared to a set of randomly deposited control nanofiber samples in the absence of the 3D printed scaffolds. SEM images also showed significant alignment of nanofibers within the pores of scaffolds, using histograms as a means for indicating the distribution of orientation angles. Statistical analysis revealed that this distribution deviates from normality due to the deviations in the tails and the existence of relatively smaller peaks at angles relative to 0°, particularly within a range of ± 50° and ± 40°. It is further found that the average peak orientation angle relative to 0° had a maximum probability of 0.014. Furthermore, the statistical analysis confirmed the distribution and significant differences in orientation between test samples with 3D-printed scaffolds and control samples. These findings demonstrate the effectiveness of resin 3D-printed scaffolds, particularly their geometric filtering effect, leading to controlled nanofiber alignment, which is proposed to be beneficial for enhancing cell adhesion, proliferation, and cell migration in tissue engineering applications.

A smart sponge with pressure–temperature dual-mode sensing for packaging and transportation

Conventional sponges are limited to providing mechanical protection and lack the capability to monitor the real-time status of transported object. Consequently, there is an urgent need to develop smart sponges that can simultaneously protect and monitor the status of objects during transportation. In this study, we have developed a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) melamine sponge (PEDOT:PSS@MS) using a dip coating-centrifugation method. The PEDOT:PSS@MS functions as a dual-mode sensor for pressure and temperature. The sensor has a maximum linear pressure sensitivity of 0.411 kPa−1 within 42.7 kPa, and a fast recovery time of 46 ms. On the other hand, the sensor exhibits a linear temperature sensitivity of 9.42 μV/K via the Seebeck effect in the range of 30 to 80 °C. By integrating multiple PEDOT:PSS@MS units into a 3D-printed packing box, the pressure and temperature orientation distribution of the transported objects can be monitored in real-time. The development of these smart sponges enhances multimodal sensors for linear response performance, holding great potential in intelligent logistics security and advanced packaging solutions.

Elimination of pores and microstructural characterization in Ti-6Al-4V alloy welds using fast-frequency double pulse TIG welding

This study utilizes a fast-frequency double pulse tungsten inert gas (FFDP TIG) process to weld 2 mm thick Ti-6Al-4V alloy, with the objective of investigating the influence of a large fast-frequency current amplitude on porosity, microstructure, and tensile properties of the weld joint. Unlike conventional TIG welding, the FFDP TIG welding process led to a reduction and elimination of porosity, and refined the prior β grain and α phase by 34.3 % and 33.3 %, respectively, while also refining the martensitic α′ structure. Stirring of the molten pool resulted in improved uniformity of grain orientation distribution, accompanied by decreased variant selection of the α phase and reduced texture strength of the α phases. Moreover, three-variant clusters of α/α′ phases with triangular morphology and micro- and nanoscale recrystallized α grains appear in the FFDP TIG weld. Concurrently, the FFDP TIG process significantly enhanced the tensile strength and ductility by 14.5 % and 114 %, respectively, compared to the conventional TIG process.

Shale anisotropic rock-physics model incorporating the effect of compaction and nonplate mixtures on clay preferred orientation

Compared with other sedimentary rocks, the strong elastic anisotropy of shale is extremely prominent, which is mainly caused by the preferred orientation and platy nature of its clay minerals. Especially in seismic reservoir characterization, a suitable and correct estimation of the shale elastic anisotropy can improve the accuracy of the shale seismic inversion and prediction. Due to the long-term compaction of shale and the rearrangement of minerals, its microstructure and macrostructure are more complex, resulting in obvious anisotropic characteristics of shale. Existing methods do not incorporate the impact of nonplate particles on clay platelets, or indirectly incorporate it through empirical formulas, resulting in poor applicability and errors in the rock-physics models. To reveal the main causes of the anisotropy of clay minerals, a theoretical model incorporating the effect of compaction and nonplate particles on the preferred orientation of clay platelets is developed using experimental data and electronic scanning results. Based on theoretical analysis, an orientation distribution function (ODF) based on the effect of compaction and nonplate particles is derived, which not only incorporates the influence of compaction but also further incorporates the effect of other nonplate particles, such as quartz, which makes the established shale anisotropic rock-physics model more reasonable and accurate. Then, an improved anisotropic shale rock-physics model is developed using the compaction and nonplate particles-based ODF. The prediction results indicate that the presence of nonplate particles has an inhibitory effect on the preferred orientation of clay platelets, which is verified by the measured experimental data and indicates that our method is reliable and effective.

Influence of one-dimensional material flow on mechanical properties and fiber orientation distribution of thin-ply carbon fiber reinforced thermoplastics sheet molding compounds

The molding flow of carbon fiber reinforced thermoplastic sheet molding compounds (CFRTP-SMC) is complex and requires a comprehensive understanding of underlying processes. This study investigates the material behavior during compression molding processes, focusing on the influence of the ratio of initial material charge area over mold area (charge ratio) on mechanical properties. The results highlight the CFRTP-SMC material's excellent flowability and moldability and confirm that the mechanical properties and internal morphology change with charge ratios. In addition, a correlation between mechanical properties and internal morphology is established through quantitative analysis of fiber orientation distributions using X-ray computed tomography. This comprehensive investigation not only sheds light on the molding ‘behavior of CFRTP-SMCs, but also underscores the importance of material charge ratios in influencing the mechanical properties. This study also provides a case study for validating numerical process models.

Effect of fast frequency double pulse current on microstructural characteristics and mechanical properties of wire arc additively manufactured Ti-6Al-4V alloy

This study introduces an innovative technique known as fast-frequency double pulse wire arc metal additive manufacturing (FFDP-WAAM). This method employs periodic fluctuations in arc plasma and force to enhance the stirring effect within the molten pool, resulting in the fragmentation of β grains and the formation of finer prior-β grains. The microstructure primarily comprises α', attributed to the high cooling rates and minimal heat accumulation. Compared to the conventional gas tungsten arc welding-based WAAM (CGT-WAAM) process, FFDP-WAAM significantly reduces α-variant selection, thereby achieving a more uniform α phase orientation distribution. Additionally, ultrasonic vibration in the FFDP-WAAM process facilitates recrystallization and mitigates residual strain. The tensile strength and elongation of the FFDP-WAAM specimens reached 939.2 MPa and 9.0 %, respectively, whereas the CGT-WAAM specimens showed a lower tensile strength of 830 MPa and elongation of 9.2 %. The enhanced strength, fatigue life and microhardness of Ti-6Al-4V produced by FFDP-WAAM is ascribed to the refined grain-size distribution. Furthermore, the low Schmid factor (SF) distribution and the stable triangular structure of Category I α-clusters are anticipated to contribute to the increased strength of the FFDP-WAAM-fabricated wall.

Analysis for site seismic hazard probability considering the orientation distribution of potential seismic sources

Analysis for site seismic hazard probability considering the orientation distribution of potential seismic sources

Polarization-Switchable Electrochemistry of 2D Layered Bi2O2Se Bifunctional Microreactors by Ferroelectric Modulation.

Ferroelectric catalysts are known for altering surface catalytic activities by changing the direction of their electric polarizations. This study demonstrates polarization-switchable electrochemistry using layered bismuth oxyselenide (L-Bi2O2Se) bifunctional microreactors through ferroelectric modulation. A selective-area ionic liquid gating is developed with precise control over the spatial distribution of the dipole orientation of L-Bi2O2Se. On-chip microreactors with upward polarization favor the oxygen evolution reaction, whereas those with downward polarization prefer the hydrogen evolution reaction. The microscopic origin behind polarization-switchable electrochemistry primarily stems from enhanced surface adsorption and reduced energy barriers for reactions, as examined by nanoscale scanning electrochemical cell microscopy. Integrating a pair of L-Bi2O2Se microreactors consisting of upward or downward polarizations demonstrates overall water splitting in a full-cell configuration based on a bifunctional catalyst. The ability to modulate surface polarizations on a single catalyst via ferroelectric polarization switching offers a pathway for designing catalysts for water splitting.

Three-dimensional fiber patterning in the annulus fibrosus can be derived from vertebral endplate topography.

The annulus fibrosus (AF) of the Intervertebral disc (IVD) is composed of concentric lamellae of helically wound collagen fibers. Understanding the spatial variation of collagen fiber orientations in these lamellae, and the resulting material anisotropy, is crucial to predicting the mechanical behavior of the complete IVD. This study builds on a prior model predicated on path-independent displacement of fiber endpoints during vertebral body growth to predict a complete, three-dimensional annulus fibrosus fiber network from a small number of subject-independent input parameters and vertebral endplate topographies obtained from clinical imaging. To evaluate the model, it was first fit to mid-plane fiber orientations obtained using polarized light microscopy in a population of bovine caudal discs for which computed tomography images vertebral endplates were also available. Additionally, the model was used to predict the trajectories based on human lumbar disc geometries and results were compared to previously reported data. Finally, the model was employed to investigate potential disc-related variations in fiber angle distributions. The model was able to accurately predict experimentally measured fiber distributions in both bovine and human discs using only endplate topography and three input parameters. Critically, the model recapitulated previously observed asymmetry between the inclinations of right- and left-handed fibers in the posterolateral aspect of the human AF. Level to level variation of disc height and aspect ratio in the human lumbar spine was predicted to affect absolute values of fiber inclination, but not this asymmetry. Taken together these results suggest that patient-specific distributions of AF fiber orientation may be readily incorporated into computational models of the spine using only disc geometry and a small number of subject-independent parameters.

Relating Quartz Crystallographic Preferred Orientation Intensity to Finite Strain Magnitude in the Northern Snake Range Metamorphic Core Complex, Nevada: A New Tool for Characterizing Strain Patterns in Ductilely Sheared Rocks

AbstractDocumenting the magnitude of finite strain within ductile shear zones is critical for understanding lithospheric deformation. However, pervasive recrystallization within shear zones often destroys the deformed markers from which strain can be measured. Intensity parameters calculated from quartz crystallographic preferred orientation (CPO) distributions have been interpreted as proxies for the relative strain magnitude within shear zones, but thus far have not been calibrated to absolute strain magnitude. Here, we present equations that quantify the relationship between CPO intensity parameters (cylindricity and density norm) and finite strain magnitude, which we calculate by integrating quartz CPO analyses (n = 87) with strain ellipsoids from stretched detrital quartz clasts (n = 49) and macro‐scale ductile thinning measurements (n = 7) from the footwall of the Northern Snake Range décollement (NSRD) in Nevada. The NSRD footwall exhibits a strain gradient, with Rs(XZ) values increasing from 5.4 ± 1.4 to 282 ± 122 eastward across the range. Cylindricity increases from 0.52 to 0.83 as Rs increases from 5.4 to 23.5, and increases gradually to 0.92 at Rs values between 160 and 404. Density norm increases from 1.68 to 2.97 as Rs increases from 5.4 to 23.5, but stays approximately constant until Rs values between 160 and 404. We present equations that express average finite strain as a function of average cylindricity and density norm, which provide a broadly applicable tool for estimating the first‐order finite strain magnitude within any shear zone from which quartz CPO intensity can be measured. To demonstrate their utility, we apply our equations to published data from Himalayan shear zones and a Cordilleran core complex.

The microstructure and mechanical properties of the laser-welded joints of as-hot rolled AlCoCrFeNi2.1 high entropy alloy

AlCoCrFeNi2.1 hot-rolled eutectic high entropy alloys were welded by laser welding, yielding a free-defect laser-welded connection. With the use of optical microscopy, EDS, EBSD, and XRD, the microstructure of the base metal (BM), fusion zone (FZ), and heat-affected zone (HAZ) of the joint was examined. The produced joint underwent tensile and micro-hardness testing as well as a fracture morphology examination. A similar tensile strength in the FZ and BM is measured, while a decrease in the elongation. The typical layered lamellar structures, in particular an FCC + BCC dual-phase structure, were all visible in the HAZ, BM, and FZ zones. The α-fiber and γ-fiber as well as other textures are determined by the ODF figure, indicating a potential orientation distribution of the as-hot rolled AlCoCrFeNi2.1 joint. A clear grain refinement characteristics in the fusion zone as a result of the uneven thermal cycling during the welding process. The results of the mechanical test demonstrate the base metal has the highest hardness value, i.e. 500–550 HV0.2, within the welded joint zone. The welded joint has a tensile strength ∼1200 MPa, which is marginally higher than ∼1150 MPa in the base metal, and an elongation that decreases by 20 % from base metal to welded joint, indicating a decrease in the plasticity of the welded joint. A combination of brittle and ductile fracture occurs in welded joints during tensile failure. This study may give possibilities for the engineering application of laser welding of AlCoCrFeNi2.1 eutectic high entropy alloy in the future.

The use of digital thread for reconstruction of local fiber orientation in a compression molded pin bracket via deep learning

A deep convolutional neural network (DCNN) was used for microstructure reconstruction using artificial intelligence (MR-AI) by predicting local average fiber orientation distributions (FOD) in a 3D prepreg platelet molded composite (PPMC) pin bracket. To train the MR-AI model, surface strain fields from residual stresses simulated in PPMC plates were used as the input to the DCNN. A training dataset included PPMC plates with various degrees of global fiber alignment, based on the information obtained from high-fidelity flow simulation of a pin bracket. The MR-AI model was then deployed to analyze FOD in the 3D pin bracket by conducting thermo-elastic residual stress analysis. Initially, the MR-AI model was established entirely on the synthetic simulation data. Then, a μCT scan of a physically molded pin bracket was used to create a finite element model that provided data for additional validation of the DCNN model. For the μCT scan finite element pin bracket the MR-AI model predicted the distribution of fiber orientation tensor components with MAE of 0.10 indicating a global prediction error of 10 %. For the flow simulated pin bracket, the MR-AI model predicted the distribution of fiber orientation tensor components with a global prediction error of 11 %. The MR-AI model showed the ability to predict regions of varying alignment in the base and flange of the pin bracket. The proposed MR-AI methodology allows for rapid prediction of FOD in geometrically complex parts and offers a promising path to detecting unique fiber orientation states in molded components.