3D Geometric Model Research Articles

Study of three-dimensional crack extension in turbine discs of short-life turbojet engines

Abstract A simulation study on the 3D crack extension of short-lived turbojet engine turbine discs was carried out using FRANC3D 3D fracture mechanics software combined with ABAQUS finite element software. By establishing a 3D geometric model of the turbine disc, the crack extension process is simulated by using the sub-model method, and the crack extension behavior and failure mode are analyzed to predict the remaining life of the cracked wheel disc. The results show that the crack expansion path matches well with the crack failure phenomenon of the turbine disc under the actual working conditions; the turbine disc crack is dominated by Type I (open Type) crack expansion, and the stress intensity factors of Type II and Type III are negligible; the crack expansion rate increases slowly with the increase of crack depth, and it rises steeply at the critical value of the fracture failure; and the residual life of the turbine disc is 32 cycles. This study provides empirical analyses for crack monitoring and life prediction of turbine discs and is of great significance for engine maintenance and reduction of end-of-life costs of turbine components.

Stress distribution by parafunctional loading on tooth–implant, implant–implant, and tooth–tooth-supported prosthesis: A comparative three-dimensional finite element analysis

Aim: The study’s objective was to evaluate the stress distribution in tooth-implant, implant-implant, and tooth-tooth supported prostheses under parafunctional loading in axial and oblique directions employing a 3D finite element analysis in the mandibular posterior region which had D3 bone (porous cortical bone and fine trabecular bone). Setting and Design: In vitro study, Finite element analysis. Meterials and Methods: Cone-beam computed tomography data was used by Mimics software (Materialize Mimics 19) to create a three-dimensional finite element simulation of the jaw. Solid Works 2018 (Dassault Systems) was used to produce a geometric 3D model of the three systems. Each model consisted of a bone, an implant, and teeth (Model I tooth-tooth supported, Model II tooth-implant supported and Model III implant-implant supported). The three models’ geometrical models were transferred to Ansys Workbench (19.2 software) for the analysis portion. A load that mimicked masticatory force was delivered in both axial and oblique directions. Statistical Analysis Used: In the present study, statistical analysis was not required because 3D finite element analysis uses deterministic numerical methods to simulate physical behavior and stress distribution patterns. Result: The results demonstrated that under the parafunctional combined loading process, the implant- implant supported prosthesis showed significantly higher stress concentrations in the bone. It was found that the cortical bone around the crestal region had the highest stresses. Conclusion: Within the constraints of this investigation, we could draw the following conclusion: Of the three models, the tooth-tooth supported prosthesis exhibited the least amount of stress distribution, which was also least when functional loading was applied in the axial direction.

A 3D Seismotectonic Model and the Spatiotemporal Relationship of Two Historical Large Earthquakes in the Linfen Basin, North China

The Shanxi Graben is a transitional zone between the Ordos Block and North China Plain with complex structures and frequent earthquakes. Six earthquakes with M ≥ 7.0 have been recorded in the area, including the 1303 Hongtong M 8 and 1695 Linfen M 7.8 earthquakes in the Linfen Basin. Research on these two large earthquakes, closely related in time and space, is lacking. Our objective was to use deep seismic reflection profiles and 3D velocity structure data from previous research, along with seismological observation results, to interpret the geological structure near the source of the two earthquakes. A 3D geometric model of the seismogenic fault was constructed, and the relationships among the deep and shallow structures, deep seismogenic environment, and two large earthquakes were explored. Differences in seismogenic environment between the southern and northern Linfen Basin were identified. The distribution of small earthquakes in the southern Linfen Basin was scattered, and the overall distribution was at depths <25 km. The small earthquakes in the northern part of the basin were dense and concentrated at depths of 25–35 km. Low-velocity layers at an approximate depth of 15–20 km in the southern basin led to differences in seismogenesis between the two regions. Based on the area of the 3D geometric model of the Huoshan Fault, the maximum magnitude of an earthquake caused by fault rupture is Mw 7.7, so the magnitude of the 1303 Hongtong earthquake might be overestimated. Numerical simulation results of Coulomb stress showed that the 1303 Hongtong earthquake had a stress-loading effect on the 1695 Linfen earthquake. The change in Coulomb rupture stress was 1.008–2.543 bar, which is higher than the generally considered earthquake trigger threshold (0.1 bar). We created a new 3D source model of large earthquakes in the Linfen Basin, Shanxi Province, providing a reference and typical cases for risk assessment of large earthquakes in different regions of the Shanxi Graben.

Automated recognition and rebar dimensional assessment of prefabricated bridge components from low-cost 3D laser scanner

Dimension quality inspections for rebar spacing and length of prefabricated bridge components are critical for subsequent efficient assembly on-site. Currently, the traditional manual inspection method is time-consuming, labor-intensive, and error-prone. The existing commercial 3D LiDAR-based methods are difficult in making balances between inspection cost, efficiency, and accuracy. Thus, the automated recognition and segmentation method of 3D point clouds acquired by a self-developed low-cost LiDAR is proposed to evaluate the rebar spacing and length of bridge prefabricated components. Due to the high-cost commercial 3D laser scanner, a spinning 2D LiDAR-based low-cost 3D laser scanner device and geometric calibration model were developed to acquire the 3D spatial point cloud. Then, two-stage automated point cloud segmentation framework is proposed with coarse extraction of the point cloud in the interest region and fine recognition of point cloud using machine learning methods, including plane segmentation and circle fitting employing random sample consensus (RANSAC) algorithm, and rebars segmentation utilizing Gaussian mixture model (GMM) and density-based spatial clustering of applications with noise (DBSCAN) algorithm. The proposed system was evaluated in two prefabricated concrete columns and shows the potential for improving the quality inspection efficiency and accuracy.

Experimental investigation of junction growth of rough contacts using X-ray computed tomography

The real contact area (RCA) of randomly rough contacts has received a great deal of attention because it correlates strongly with friction, lubrication, sealing, and conductivity. Simulations have revealed that the RCA associated with deterministic normal squeezing loads increases when tangential loads are also applied, in a phenomenon called junction growth. However, experimental investigations of the junction growth of randomly rough contacts are rare. Here, we used X-ray computed tomography (CT) to measure junction growth when two aluminum alloy surfaces were in contact. A high-resolution experimental setup was used to apply loads and observe contact behaviors at a resolution of 4 µm. The RCA and average contact gaps were computed using a three-dimensional (3D) geometric model constructed from gray CT images using the Otsu thresholding method. The results showed that the RCA increased as the normal load increased. The RCA increased by 22.67% after a tangential load was applied (junction growth), and the average gap decreased by 14.01% after a tangential load was applied. Thus, X-ray CT accurately measured the junction growth as a novel quantitative method.

3D reconstruction of semantic-rich digital twins for ACMV monitoring and anomaly detection via scan-to-BIM and time-series data integration

Current research in air-conditioning and mechanical ventilation (ACMV) operation focuses on isolated sub-processes and analytical models. Digital twins, as digital replicas of assets, processes, or systems in the built environment, enable facilities manager (FM) to gain insights into the physical features of space, equipment performance, and energy efficiency. This study presents the 3D reconstruction of semantic-rich digital twins, which encompasses conditional and machine learning-enabled monitoring with 3D geometric models, for ACMV modeling and operation. The proposed framework involves a hybrid rule-based and data-driven approach to forecast the performance of indoor environment and identify potential anomalies throughout ACMV operation. Following this, a scan-to-BIM process is undertaken, with the aid of Simultaneous Localization and Mapping algorithms, to semi-automatically generate the as-built geometric models. Lastly, semantic enrichment of BIM is performed by incorporating time-series data from the rule-based and data-driven approach with 3D geometric models. The proposed approach supports the reconstruction of content-aware and semantic-rich digital twins, which utilize sensor-derived time-series data and 3D geometric models, to conduct advanced analysis for intelligent ACMV operation towards energy efficiency and occupant comfort.

VOX-STORM: A stochastic 3D model based on a dual voxel-mesh architecture for the morphological characterization of aggregates

Measuring the 3D morphological properties of granular objects such as aggregates is a critical issue in many fields of science and industry, especially when the objects are fragile or hard to sample. For these reasons, non-invasive techniques based on image analysis are being developed. However, most image analysis techniques can only measure 2D properties. This paper presents a new approach based on both image analysis and a 3D stochastic geometric model called VOX-STORM (VOXel-based STOchastic geometRical Model) to estimate 3D morphological properties. By adjusting the parameters of the model, the latter is able to generate populations of objects whose 2D property distributions match those measured by image analysis, and to predict 3D morphological property distributions. The model is based on a dual architecture combining voxelized structure and alpha-shape meshing of the external surface, which makes object generation extremely fast (about 1000 objects in 20 s), while allowing rapid computation of 3D characteristics. The method is validated twice, first on 3D printed aggregates and then on a population of 40,000 synthetic aggregates, with mean errors of less than 2.5% in all cases and less than 1% for 2D properties. It is then applied to two sets of images of latex aggregates captured by a morphogranulometer. The morphological property distributions and fractal dimensions are compared to ground truth in the 2D case and to laser diffraction measurements in the 3D case. The results are also compared with two other recent stochastic geometric models, and the VOX-STORM model outperforms them in all scenarios, as well as in speed of execution, while agreeing with experimental measurements. Finally, directions for future work are suggested.

Flexibility evaluation of psammophytes using Young’s modulus based on 3D numerical simulation

Flexible psammophytes play an important role in controlling soil wind erosion and desertification, owing to their characteristics. Although flexibility of psammophytes has been considered in previous studies, the interaction between flexible psammophytes and the surrounding airflow field still remained unclear. In this study, we used the Young’s modulus to describe plant flexibility and conducted a 3D computational fluid dynamics simulation using a standard k-ε model and a fluid–structure interaction model. Taking Caragana korshinskii (Caragana), a typical psammophyte, as the research object, we constructed 3D geometric models with different diameters to simulate the airflow field around the flexible psammophytes. By comparing with the simulation results of rigid plants and simulation results of flexible plants at different wind speeds, we could verify the rationality of the simulation method. Based on the simulation results, the maximum swing amplitude of the model and the Young’s modulus were found to have a negative correlation, presenting an exponential functional relationship with good fitting. The relationship between the actual Young’s modulus of the plant branches and that of different diameter models in the numerical simulation was also established. This study is expected to improve our basic understanding of the interaction between flexible psammophytes and the surrounding airflow field, and provide some qualitative reference for the numerical simulation of the airflow field around flexible psammophytes.

Lung divisions for models of cardiopulmonary interaction – preliminary tests

Abstract Introduction: The perfusion of a part of the lung depends on its distance from the pulmonary trunk (differences in vascular resistance) and on the horizontal plane (differences in hydrostatic pressure). The aim of this study was to determine the geometric parameters characterising their positions and sizes in order to analyse the diffusion of the ventilation/perfusion ratio. Material and methods: A developed virtual respiratory system has been supplemented with an appropriate model of pulmonary circulation that uses a lung outline that is divided into parts based on an anatomical atlas and a CT image; it comprises a 3D geometric model of the lungs that was developed using the Inventor CAD software (Autodesk, Inc, San Francisco, USA). Each panel was divided into 2 horizontal and 8 vertical parts; the 16-part division was then modified. Results: When taking human lungs as a research object and simulating their accompanying physical, biological, or biochemical phenomena, one necessary task is to construct a spatial model of the lungs that takes into account, and maintains awareness of, the limitations of the source of data that is relied upon. The developed modified geometric model of lung division turned out to be useful and was successfully applied to a virtual patient, among others, as part of the VirRespir project. Conclusions: Finally, we can conclude that the virtual cardiorespiratory system thus elaborated may serve as a proper tool for the preliminary analysis of such complex interactions, considering the elaborated model of the lung’s divisions and its future improvements.

Analyzing Temperature Distributions and Gradient Behaviors for Early-Stage Tumor Lesions in 3D Computational Model of Breast

The computational modelling and analysis of internal and external temperature distributions and their gradients, associated with the first stage of mammary tumors, was performed to relate thermal parameters to relevant tumor characteristics. A realistic 3D geometric model of breast anatomy was used to simulate tumor cases that were characterized in real life at their primary clinical stage. The thermophysical parameters of three tumors were extracted to implement the models; a fourth case without a tumor was used as a reference to provide quantitative measurements of temperature increases and gradient changes. The analysis considered superficial and internal temperature distributions and gradients, computed throughout specific paths. Finally, an evaluation was made of the ability of the thermometric technologies available today to detect the changes estimated in simulations. Maximum temperature increments in the range of 2.30 to 3.20 °C and in the range of 0.15 to 0.30 °C were found on internal and superficial paths, respectively. Internal gradient peak magnitudes fluctuated within the range of 0.34 to 1.14 °C/mm. Thermal results indicated a direct correlation between tumor size and temperature rise. Nevertheless, gradient results showed that the heat generation rate, an indicator of tumor malignancy, was directly proportional to internal gradient maximum peaks, which were related to tumor boundaries regardless of tumor size.

UAV vision-based crack quantification and visualization of bridges: system design and engineering application

Accurately measuring visible cracks in bridges is crucial for their structural health diagnosis, damage detection, performance evaluation, and maintenance planning. The primary means of visual crack detection still relies heavily on manual visual inspection, an inefficient process that can pose significant safety risks. This article develops a unmanned aerial vehicle (UAV) vision-based surface crack measurement methodology and visualization scheme for the bridges that can detect and measure cracks automatically with improved efficiency. The surface crack measurement methodology is achieved by designing a three-stage crack sensing system including the You Only Look Once-based crack recognition, U-shaped network-based crack segmentation, and deep-vision-based crack width calculation. This workflow is integrated into a comprehensive UAV inspection system, which is intended for operation at the field. The surface crack visualization scheme is accomplished by taking advantage of time-series image fusion, GPS information migration, and three-dimensional (3D) point cloud technique to reconstruct the 3D geometrical model of the tested bridge, which is convenient for unveiling the crack information in the bridge. The proposed methodology was successfully validated by a case study on an arch bridge. The achievement of this article promotes the UAV vision-based bridge’s surface crack inspection technology to a new status that no preparation for pasting calibration marker is needed, and crack identification, segmentation, and width calculation are realized promptly during the UAV flying on-site, as well as damage evaluation for bridges is visually fulfilled based on the reconstructed digital-graphical 3D model. The working environments and influencing factors to the developed system are sufficiently discussed. Certain limitations in the current application are pointed out for future improvements.

Deep Blind Fault Activity—A Fault Model of Strong Mw 5.5 Earthquake Seismogenic Structures in North China

North China is one of the high-risk areas for destructive and strong earthquakes in mainland China and has experienced numerous strong historical earthquakes. An earthquake of magnitude MW 5.5 struck Pingyuan County, Dezhou city, in Shandong Province, China, on 6 August 2023. This earthquake was the strongest in the eastern North China Craton since the 1976 Tangshan earthquake. Since the earthquake did not produce surface ruptures, the seismogenic structure for fault responsible for the Pingyuan MW 5.5 earthquake is still unclear. To reveal the subsurface geological structure near the earthquake epicenter, this study used high-resolution two-dimensional (2D) seismic reflection profiles and constructed a three-dimensional (3D) geometric model of the Tuqiao Fault by interpreting the faults in the seismic reflection profiles. This study further combined focal mechanism solutions, aftershock clusters, and other seismological data to discuss the seismogenic fault of the Pingyuan MW 5.5 earthquake. The results show that the Tuqiao Fault is not the seismogenic fault of the MW 5.5 earthquake. The actual seismogenic structure may be related to the NE-oriented high-angle strike-slip blind fault developed in the basement. We further propose three possible fault models for the strong seismogenic structure in North China to discuss the potential seismotectonics in this region.

Estimation of load-carrying capacity of cracked RC beams using 3D digital twin model integrated with point clouds and images

Digital twin (DT) is capable of managing, simulating, and future performance prediction of existing infrastructures by integrating three-dimensional (3D) geometric model and finite element (FE) model. This study aims to automatically generate geometric DT of existing RC members using point clouds and incorporate damages detected from images into FE models. An edge-based modeling method was proposed to extract sharp features for geometry reconstruction with incomplete point clouds, and an automated procedure was established for registering images to point clouds, mapping cracks detected in images to FE models, and assigning reduced material properties. Four RC beams were tested in a laboratory to validate the proposed method. Existing cracks were found to have a significant effect on structural capacity and failure mode. The results also showed that the developed FE model produced a good agreement between experimental and predicted failure loads while providing a more efficient and time-saving assessment protocol.

CityGML Grotto ADE for modelling niches in 3D with semantic information

The regions of East Asia, as well as South Asia and the Middle East are rich in cultural heritage of grottoes where a large number of Buddhist niches exist. Three-dimensional (3D) semantic modelling enriches 3D geometric models with an understanding of the historical and cultural value of cultural heritage, facilitating interoperability and analysis beyond mere visualization. 3D models with semantic information act as essential digital infrastructure for heritage management, knowledge dissemination and simulation analysis in cultural heritage. However, due to the lack of standardized data model for the grotto domain, it is difficult to exchange information, share knowledge and the advancement of spatial analysis and simulation. In order to fill the above-mentioned gap, this study develops a data model for niches as a CityGML Application Domain Extension (ADE) based on the CityGML 3.0 standard. In this ADE, niche components and their attributes are defined on two semantic levels, i.e., niche structural component and niche component member. A famous niche in China belonging to the World Heritage was selected as a case study to demonstrate the integration of geometries, semantics and attributes, illustrating that the extended ADE module complies with the CityGML 3.0 standard. This study provides novel insights into the 3D semantic modelling of niches as well as expands the applications scope of CityGML standard within the cultural heritage sector.

THE METHOD OF SELECTING THE MOST APPROPRIATE MODIFICATION OF THE MECHANISM USING COMPUTER TECHNOLOGIES

The article presents a method for identifying the most appropriate modification of the mechanism with the required output shaft rotation frequency by constructing various geometric models and calculation schemes. This technique based on the design and analysis of modification of the vibration stand mechanism for testing measuring equipment and products for vibration resistance and vibration resistance. The strength analysis of contact stresses and bending stresses in the engagement zone of the elements under various external and boundary conditions was performed using analytical and computer methods. A 3D geometric model of the parts is being created with the display of traces of operation on the surface of the parts, anticorrosion coatings, using materials of various heat treatment in the Compass 3D V.21 package. The most appropriate modification of the mechanism is identified by analyzing the distributions of maximum equivalent stresses according to Mises, the main stresses according to geometric models of parts. If these stresses exceed the limit values or the mechanism is underloaded, the geometric dimensions of the transmission parts should be changed, another material for the transmission parts should be selected and the strength calculations should be repeated.

Simulation of Automatically Annotated Visible and Multi-/Hyperspectral Images Using the Helios 3D Plant and Radiative Transfer Modeling Framework.

Deep learning and multimodal remote and proximal sensing are widely used for analyzing plant and crop traits, but many of these deep learning models are supervised and necessitate reference datasets with image annotations. Acquiring these datasets often demands experiments that are both labor-intensive and time-consuming. Furthermore, extracting traits from remote sensing data beyond simple geometric features remains a challenge. To address these challenges, we proposed a radiative transfer modeling framework based on the Helios 3-dimensional (3D) plant modeling software designed for plant remote and proximal sensing image simulation. The framework has the capability to simulate RGB, multi-/hyperspectral, thermal, and depth cameras, and produce associated plant images with fully resolved reference labels such as plant physical traits, leaf chemical concentrations, and leaf physiological traits. Helios offers a simulated environment that enables generation of 3D geometric models of plants and soil with random variation, and specification or simulation of their properties and function. This approach differs from traditional computer graphics rendering by explicitly modeling radiation transfer physics, which provides a critical link to underlying plant biophysical processes. Results indicate that the framework is capable of generating high-quality, labeled synthetic plant images under given lighting scenarios, which can lessen or remove the need for manually collected and annotated data. Two example applications are presented that demonstrate the feasibility of using the model to enable unsupervised learning by training deep learning models exclusively with simulated images and performing prediction tasks using real images.

STUDY OF THE INFLUENCE OF THE GEOMETRIC FORM OF PIGS ON THE EFFICIENCY OF CLEANING PIPELINES

The effect of the geometric shape of the pigs on their passage and pipeline cleaning efficiency was investigated by numerical modeling and experimentally. For this, a 3D geometric model was built and experimental samples with a convex front and a concave back part were made from silicone compound. The properties of the pigs material are described by the Mooney-Rivlin deformation potential energy model. The simulation results are visualized by constructing three-dimensional colored fields of equivalent Mises stresses on the contours of the pigs for different values of the friction coefficient between its side surface and the inner wall of the pipeline. It was found that making the rear part of the pigs concave leads to a significant increase in the contact forces between the pigs and the inner wall of the pipe, which has a significant impact on its passage and the efficiency of cleaning the internal cavity of the pipeline. Moreover, with an increase in the coefficient of friction, the equivalent stresses near the rear end of the pigs increase, and therefore the contact forces increase and the flow through the pigs decreases.

Methodology for the Integration of Structural Health Assessment of Masonry Bridges into HBIM

ABSTRACT A methodology is proposed to efficiently develop BIM models of masonry arch bridges, with the objective of generating databases (Level of Information, LoI) associated with 3D geometrical models, incorporating different levels of detail (LoD). The use of parametric libraries is implemented to develop the models. The first step is to perform an experimental campaign to obtain initial data. With these data and the parametric library previously created, a parametric model of the structure is generated (low LoD). A map of the vulnerable areas of the structure is created on this model and the available information is linked to it. A structural model (high LoD) is also created and calibrated. With all this information, an HBIM file is generated. A second experimental campaign is performed on the structure using non-destructive techniques. Point clouds, OMA data, photographs, and visual inspections from the different experimental campaigns are compared to the original HBIM file. In addition, to validate the usefulness of the parametric library, its implementation is carried out on three other historic masonry structures. This comprehensive and technologically advanced approach proves to be a promising strategy for the conservation and sustainable management of architectural heritage.

Evaluation of women's aging influence on sperm passage inside the fallopian tube using 3D dynamic mechanical modeling.

The fallopian tubes play an important role in human fertility by facilitating the spermatozoa passage to the oocyte as well as later actively facilitating the fertilized oocyte transportation to the uterus cavity. The fallopian tubes undergo changes involving biological, physical, and morphological processes due to women aging, which may impair fertility. Here, we have modelled fallopian tubes of women at different ages and evaluated the chances of normal and pathological sperm cells reaching the fertilization site, the ampulla. By utilizing a unique combination of simulative tools, we implemented dynamic three-dimensional (3D) detailed geometrical models of many normal and pathological sperm cells swimming together in 3D geometrical models of three fallopian tubes associated with different women's age groups. By tracking the sperm cell swim, we found that for all age groups, the number of normal sperm cells in the ampulla is the largest, compared with the pathological sperm cells. On the other hand, the number of normal sperm cells in the fertilization site decreases due to the morphological and mechanical changes that occur in the fallopian tube with age. Moreover, in older ages, the normal sperm cells swim with lower velocities and for shorter distances inside the ampulla toward the ovary. Thus, the changes that the human fallopian tube undergoes due to women's aging have a significant influence on the human sperm cell motility. Our model of sperm cell motility through the fallopian tube in relation to the woman's age morphological changes provides a new scope for the investigation and treatment of diseases and infertility cases associated with aging, as well as a potential personalized medicine tool for evaluating the chances of a natural fertilization per specific features of a man's sperm and a woman's reproductive system.

Generation Mechanism and Beaming of Jovian nKOM From 3D Numerical Modeling of Juno/Waves Observations

AbstractThe narrowband kilometric radiation (nKOM) is a Jovian low‐frequency radio component identified as a plasma emission produced in the region of the Io plasma torus. Measurements from the Waves instrument onboard the Juno spacecraft permitted to establish the distribution of nKOM occurrence and intensity as a function of frequency and latitude. We have developed a 3D geometrical model that can simulate at large scale the plasma emissions occurrence observed by a spacecraft based on an internal Jovian magnetic field model and a diffusive equilibrium model of the plasma density in Jupiter's inner magnetosphere. With this model, we propose a new method to discriminate the generation mechanism, wave mode, beaming and radio source location of plasma emissions. Here, this method is applied to the study of the nKOM observed from all latitudes by the Juno/Waves experiment to identify which conditions reasonably reproduce the observed occurrence distribution versus frequency and latitude. The results allow us to exclude the two main nKOM models published so far, and to show that the emission is produced at the local plasma frequency and then beamed anti‐parallel to the local density gradient into free space. We also propose that depending on its latitude, Juno observes two distinct kinds of nKOM: the low frequency nKOM in ordinary mode at high latitudes, and the high frequency nKOM on extraordinary mode at low latitudes. Both radio source locations are found to be distributed near the centrifugal equator ranging from the outer edge to the inner edge of the Io plasma torus.