Full 3D Model Research Articles

Application of Intelligent Art Design Technology Based on MBD

Contemporary public art needs to be carefully designed with its unique advantages to achieve its wider diversity, participation and interaction. Based on the MBD process model, the basic process description and evaluation method of process design features are established. Based on the model definition, the key equipment information of process design is the initial data of process optimization. The process design and optimization are realized. It provides an application method based on full 3D model for art design and optimization. An application example of process design is established. Combined with the actual demonstration of MBD, the design optimization process model is an important guarantee for process design. The results show that the distribution of intelligent hardware users in South China accounts for 34.9%, and that in Central China accounts for at least 16.9%.

Gravity mapping of basement depth in seismogenic, fault-controlled basins: The case of Middle Aterno Valley (Central Italy)

Ground-shaking phenomena in intermontane basins emplaced in seismically active areas are strongly affected by sediment thickness. There, the development of human settlements, encouraged because of the flat topography in a mostly mountainous region, implies demographic growth and an increased seismic risk, as recent earthquakes in Central Italy confirmed. The knowledge of the thickness of the basin infills and of their density distribution is critical for the ground-motion amplification analysis.We apply the recently proposed ITerative RESCaling (ITRESC) method for 3D gravity modelling to the Middle Aterno Valley (Apennines, central Italy), a fault-controlled basin where a strong seismic activity recently occurred. Although the structural framework was previously investigated through 1D or 2D geophysical studies, here for the first time a full 3D model of the carbonate basement morphology is computed by the inversion of gravity data.Differently from usual gravity modelling approaches, the ITRESC technique 1) does not assume a density contrast function, which is instead determined through a data-driven process, and 2) integrates geological or geophysical constraints to define a global “gravity/depth-to-basement” rescaling law, valid in all the investigated area.Our model integrates a number of depth constraints of different nature while at the same time honoring the gravity anomalies. The obtained gravity model of the basement depth shows several analogies with previous studies, although with significant, localized discrepancies. The results of this study are only partially consistent with a structural evolution of the Middle Aterno Valley through a polyphasic sequence, as previously hypothesized.

Simulation Optimization and improvement of conducted emission for DC/DC converter in electric vehicle

Based on the simulation of conducted emission noise voltage of electric vehicle DC/DC converter, this paper uses a co-simulation analysis method with HFSS- Simplorer, to predict the optimization and improvement impacts by adding magnetic core into the full 3D model, or changing the value of lumped capacitor in the simulation circuit. According to the difference of the simulation results, the effectiveness of improvement can be determined quickly, it provides an important support for the location and rectification of component level electromagnetic interference problem of conducted emission in DC/DC converter.

Wall-function method used to simplify the solid oxide fuel cell model

Numerical model is a powerful tool in the solid oxide fuel cell (SOFC) study, but its application is seriously restricted by the tremendous demand of computational resources and time due to the high aspect ratio of functional layers. In this paper, the wall-function method widely used in turbulent flow model is introduced to simplify the SOFC model. By analyzing the similarity in SOFC functional layers to the viscous flow nearby wall, a set of wall functions is developed to calculate the generating current in functional layers instead of the traditional complex partial differential equations. Compared with traditional full 3D model, the simplified model based on wall-function method shows similar accuracy but uses only about one third mesh elements and spends less than a half of solution time. Numerical results show that there are two important advantages for the wall-function method: 1) it allows a coarse mesh which can significantly reduce the computational storage and time; 2) it allows the introduction of other information in wall-functions and uses denser points in thickness direction which can considerably improve the accuracy of model.

Measurement error using a SeeMaLab structured light 3D scanner against a Microscribe 3D digitizer.

BackgroundGeometric morphometrics is a powerful approach to capture and quantify morphological shape variation. Both 3D digitizer arms and structured light surface scanners are portable, easy to use, and relatively cheap, which makes these two capturing devices obvious choices for geometric morphometrics. While digitizer arms have been the “gold standard”, benefits of having full 3D models are manifold. We assessed the measurement error and investigate bias associated with the use of an open-source, high-resolution structured light scanner called SeeMaLab against the popular Microscribe 3D digitizer arm.MethodologyThe analyses were based on 22 grey seal (Halichoerus grypus) skulls. 31 fixed anatomical landmarks were annotated both directly using a Microscribe 3D digitizer and on reconstructed 3D digital models created from structured light surface scans. Each skull was scanned twice. Two operators annotated the landmarks, each twice on all the skulls and 3D models, allowing for the investigation of multiple sources of measurement error. We performed multiple Procrustes ANOVAs to compare the two devices in terms of within- and between-operator error, to quantify the measurement error induced by device, to compare between-device error with other sources of variation, and to assess the level of scanning-related error. We investigated the presence of general shape bias due to device and operator.ResultsSimilar precision was obtained with both devices. If landmarks that were identified as less clearly defined and thus harder to place were omitted, the scanner pipeline would achieve higher precision than the digitizer. Between-operator error was biased and seemed to be smaller when using the scanner pipeline. There were systematic differences between devices, which was mainly driven by landmarks less clearly defined. The factors device, operator and landmark replica were all statistically significant and of similar size, but were minor sources of total shape variation, compared to the biological variation among grey seal skulls. The scanning-related error was small compared to all other error sources.ConclusionsAs the scanner showed precision similar to the digitizer, a scanner should be used if the advantages of obtaining detailed 3D models of a specimen are desired. To obtain high precision, a pre-study should be conducted to identify difficult landmarks. Due to the observed bias, data from different devices and/or operators should not be combined when the expected biological variation is small, without testing the landmarks for repeatability across platforms and operators. For any study necessitating the combination of landmark measurements from different operators, the scanner pipeline will be better suited. The small scanning-related error indicates that by following the same scanning protocol, different operators can be involved in the scanning process without introducing significant error.

Longhu pagoda: Advanced numerical investigations for assessing performance at failure under horizontal loads

As an important historical building type for human beings, ancient masonry pagodas have key research significance. They are widely diffused in China, and they are tower-like masonry structures, usually massive and tall. This paper takes the Longhu pagoda as a case-study: it was built in 1342 CE, and it is the only masonry pagoda from the Yuan Dynasty. It is located in the Sichuan Province (China), it has a square plane, and the height is about 33 m. This construction severely suffered the so-called “2008 Sichuan Earthquake”. A full 3D model of the Longhu Pagoda has been obtained and subsequently meshed. The FE software Abaqus/CAE has been used for carrying out static analyses, pushover analyses and non-linear dynamic analyses. The material non-linearities have been taken into consideration employing the so-called Concrete Damage Plasticity (CDP) model available in Abaqus. Modal analyses have shown that FEM results and simplified cantilever model results may agree. Pushover analyses (POs) have been performed under different load conditions and along the four principal bending directions to estimate the global capacities and the corresponding collapse mechanisms. Non-linear dynamic analyses (NLDAs) allowed putting in evidence the accuracy of the results provided by the pushover analyses; besides, they gave helpful information about the crack propagation, confirming the damage reported on-site after the 2008 earthquake. The state of damage found and the related failure mechanisms have been deeply commented. Moreover, some sensitivity analyses have been performed to study the influence of some material parameters on the pushover results. Furthermore, two fictitious 3D models of the pagoda have been created by doubling and removing two floors to investigate the influence of the tower slenderness. The before mentioned analyses have also been performed on such models, and the impact of the slenderness on this structural typology has been studied. Finally, the kinematic theorem of limit analysis has been applied, and some values of collapse acceleration have been consequently computed using different a-priori established collapse mechanisms. The results have been compared with FE simulations results, and the ability of limit analysis to quickly predict the seismic vulnerability has been discussed.

Towards best practice in numerical simulation of blind rivet nut installation

The present paper derives best practices to accurately simulate the installation process of a Blind Rivet Nut (BRN) using FEA. A BRN is a mechanical fastener used to equip plate material with a threaded part. The installation of a BRN inherently induces a high contact force which can have detrimental consequences when applied to non-metals such as polymer composite materials. The effects of the localized stress in the plate on the mechanical performance of the BRN can be studied with the aid of finite element simulations. To this end, the joining by forming process itself is accurately simulated using a computational efficient axisymmetric 2D model. The 2D model enables to predict the metal flow and internal state of stress after setting with sufficient accuracy. The latter is validated using a full 3D model and a multitude of experimental observations. It is shown that the large strain flow curve of the BRN material needs to be adequately identified. An industrially relevant calibration procedure is presented mitigating the experimental effort. In addition, material test selection in case of highly anisotropic BRN materials is discussed based on a thorough stress state analysis. Finally, the sensitivity of the BRN geometry to a change in the most relevant geometrical parameters is demonstrated. The presented experimental methods and numerical models provide fundamental insights in the forming mechanism including process-induced ductile damage while installing the BRN. The latter will foster the development of new BRN applications in multi-material mechanical design.

Multi-objective topology optimization of pin-fin heat exchangers using spectral and finite-element methods

Forced convective pin-fin heat exchangers, due to the high wet surface area per volume and the hindered thermal boundary layers, feature low thermal resistances. However, the considerable coolant pressure drop, particularly for densely packed fin arrays, imposes operational costs for pumping power supply. This paper develops a multi-objective topology optimization approach to optimize sink geometries in order to minimize thermal resistance and pressure loss, concurrently. In accordance to the pin-fin geometrical characteristics, a dedicated pseudo-3D conjugate heat transfer model is utilized, by assuming periodic flow and fin design pattern, to reasonably reduce the high cost of full-3D model optimization. For the solution of flow part, a pseudo-spectral scheme is used, which is intrinsically periodic and features a high spectral accuracy, and the finite element method for the non-periodic conjugate heat transfer model. Exact partial derivatives of the discrete solutions are obtained analytically by hand-differentiation. This task is rather convenient for the flow part, due to the simplicity of the pseudo-spectral implementation; however, the MATLAB symbolic toolbox is selectively utilized for the finite element code to ensure an error-free implementation. Finally, the sensitivities are computed directly or via a discrete adjoint method, for the flow and heat models, respectively. To examine the present approach, two approaches are used for optimization of a practical cooling task: constrained and unconstrained multi-objective formulations, where in all cases more emphasis is placed on thermal resistance minimization. A series of optimized heat sink geometries via constrained or unconstrained multi-objective optimizations are obtained to examine practical utility of the present approach. The optimized topologies demonstrated superior cooling performances at lower costs of pressure losses compared to conventional (circular) in-line and staggered fins, and confirmed the supremacy of topology over pure sizing optimization.

Shear band evolution phenomena in direct shear test modelled with DEM

A direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear box during a geotechnical test. Numerical calculations were performed with open-source discrete code YADE. The full 3D model was used, in order to eliminate some non-physical phenomena. The numerical stress-strain curve was directly compared with the laboratory results and good agreement was obtained. The focus was on the shape of the localized zone, the properties of this zone and its behaviour. The movement of the individual grains was studied. In our analysis, the stresses were also taken into consideration. The conclusions were validated on tests with different initial void ratio (dense or loose material) and with different vertical pressure.

Rigorous 3D modeling of confocal microscopy on 2D surface topographies

Although optical 3D topography measurement instruments are widespread, measured profiles suffer from systematic deviations occurring due to the wave characteristics of light. These deviations can be analyzed by numerical simulations. We present a 3D modeling of the image formation of confocal microscopes. For this, the light-surface interaction is simulated using two different rigorous methods, the finite element method and the rigorous coupled-wave analysis. The image formation in the confocal microscope is simulated using a Fourier optics approach. The model provides high accuracy and advantages with respect to the computational effort as a full 3D model is applied to 2D structures and the lateral scanning process of the confocal microscope is considered without repeating the time consuming rigorous simulation of the scattering process. The accuracy of the model is proved considering different deterministic surface structures, which usually cause strong systematic deviations in measurement results. Further, the influences of apodization and a finite pinhole size are demonstrated.

Quasi-3D modeling of Li-ion batteries based on single 2D image

Electrochemical physics-based simulations of Li-ion batteries using a mesoscale 3D structure of porous electrodes are one of the most effective approaches for evaluating the local Li concentration in active materials and the Li-ion concentration in electrolytes. However, this approach requires considerable computational resources compared with a simple 2D or 1D homogeneous simulation. In this work, we developed an advanced electrochemical physics-based simulation method for Li-ion batteries that enabled a quasi-3D simulation of charge/discharge using only a single 2D slice image. The governing equations were based on typical theories of electrochemical reactions and ion transport. From referencing the 2D plane, the model was able to simulate both the Li concentration in the active material and the Li-ion concentration in the electrolyte for their subsequent consideration in a virtual 3D structure. To confirm the validity of our proposed model, a full 3D discharge simulation with randomly packed active material particles was performed and compared with the results of the quasi-3D model and a simple-2D model. Results indicated that the quasi-3D model properly reproduced the sliced Li and Li-ion concentrations simulated by the full 3D model in the charge/discharge process, whereas the simple-2D simulation partially overestimated or underestimated these concentrations. In addition, the quasi-3D model made it possible to dramatically decrease the computation time compared to the full-3D model. Finally, we applied the model to an actual scanning electron microscopy equipped with a focused ion beam (FIB-SEM) image of a positive electrode.Graphic abstract

A novel no-sensors 3D model reconstruction from monocular video frames for a dynamic environment.

Occlusion awareness is one of the most challenging problems in several fields such as multimedia, remote sensing, computer vision, and computer graphics. Realistic interaction applications are suffering from dealing with occlusion and collision problems in a dynamic environment. Creating dense 3D reconstruction methods is the best solution to solve this issue. However, these methods have poor performance in practical applications due to the absence of accurate depth, camera pose, and object motion.This paper proposes a new framework that builds a full 3D model reconstruction that overcomes the occlusion problem in a complex dynamic scene without using sensors’ data. Popular devices such as a monocular camera are used to generate a suitable model for video streaming applications. The main objective is to create a smooth and accurate 3D point-cloud for a dynamic environment using cumulative information of a sequence of RGB video frames. The framework is composed of two main phases. The first uses an unsupervised learning technique to predict scene depth, camera pose, and objects’ motion from RGB monocular videos. The second generates a frame-wise point cloud fusion to reconstruct a 3D model based on a video frame sequence. Several evaluation metrics are measured: Localization error, RMSE, and fitness between ground truth (KITTI’s sparse LiDAR points) and predicted point-cloud. Moreover, we compared the framework with different widely used state-of-the-art evaluation methods such as MRE and Chamfer Distance. Experimental results showed that the proposed framework surpassed the other methods and proved to be a powerful candidate in 3D model reconstruction.

Generating Building Infrastructure Modeling Using cGAN

In today’s world to propose a building model to an investor and builder, an architect has to undergo a full process of making a full 3D model of a building and detailing each and every aspect of the building. The details include the interior and exterior of the building. But, at the end the investor and builder are interested in the front elevation design of the building and not the detailed part. Hence, for providing the important information like faces of the building, we propose to generate new synthetic versions of images from sketch, labels, and edges. The model used for developing this platform i.e., pix2pix is an approach for training CNN for image-to-image translations. Pix2pix can be demonstrated on various image translation tasks; transforming an image from one domain to another or to a corresponding output could have innumerable applications, changing art styles, building infrastructure modelling and criminal identification are just a few applications. The building infrastructure modeling platform proposed aims to be feasible and have wide applicability for the architects by providing an interactive pallet and a convenient platform.

Underwater photogrammetry for close-range 3D imaging of dry-sensitive objects: The case study of cephalopod beaks.

Technical advances in 3D imaging have contributed to quantifying and understanding biological variability and complexity. However, small, dry‐sensitive objects are not easy to reconstruct using common and easily available techniques such as photogrammetry, surface scanning, or micro‐CT scanning. Here, we use cephalopod beaks as an example as their size, thickness, transparency, and dry‐sensitive nature make them particularly challenging. We developed a new, underwater, photogrammetry protocol in order to add these types of biological structures to the panel of photogrammetric possibilities.We used a camera with a macrophotography mode in a waterproof housing fixed in a tank with clear water. The beak was painted and fixed on a colored rotating support. Three angles of view, two acquisitions, and around 300 pictures per specimen were taken in order to reconstruct a full 3D model. These models were compared with others obtained with micro‐CT scanning to verify their accuracy.The models can be obtained quickly and cheaply compared with micro‐CT scanning and have sufficient precision for quantitative interspecific morphological analyses. Our work shows that underwater photogrammetry is a fast, noninvasive, efficient, and accurate way to reconstruct 3D models of dry‐sensitive objects while conserving their shape. While the reconstruction of the shape is accurate, some internal parts cannot be reconstructed with photogrammetry as they are not visible. In contrast, these structures are visible using reconstructions based on micro‐CT scanning. The mean difference between both methods is very small (10−5 to 10−4 mm) and is significantly lower than differences between meshes of different individuals.This photogrammetry protocol is portable, easy‐to‐use, fast, and reproducible. Micro‐CT scanning, in contrast, is time‐consuming, expensive, and nonportable. This protocol can be applied to reconstruct the 3D shape of many other dry‐sensitive objects such as shells of shellfish, cartilage, plants, and other chitinous materials.

Local-inertial shallow water model on unstructured triangular grids

Two-dimensional shallow water models are widely used for flood risk assessment. Application of these models to large-scale urban areas significantly increases the computational cost as it requires high-resolution simulations to capture the complex hydrodynamic processes. Hence, simplified models that are based on local-inertial formulations have been proposed by different researchers. Although these models are successful in simulating floods, their applications are limited by the use of structured grids and instability issues. Structured grids do not have the flexibility of providing different mesh resolutions to model the computational domain. Importantly, in the case of structured grids, the use of a single grid or the combination of finer and coarser grids inevitably increases the overall computational time. To overcome all these problems, an unstructured grid-based local-inertial model is developed. The performance of the model is rigorously evaluated by solving analytical test cases and simulating an urban flood in Glasgow, UK. Finally, the model is applied to simulate a catastrophic flood event that occurred in Chennai, India. The simulated water depths and inundation extents are compared with observed data or full-2D model results. The investigations show that the developed model has the potential for simulating floods on a large-scale with high-resolution grids at a comparatively lower computational cost than its predecessors for a similar range of accuracy.

X-ray micro-tomographic data of live larvae of the beetle Cacosceles newmannii.

Quantifying insect respiratory structures and their variation has remained challenging due to their microscopic size. Here we measure insect tracheal volume using X-ray micro-tomography (μCT) scanning (at 15μm resolution) on living, sedated larvae of the cerambycid beetle Cacosceles newmannii across a range of body sizes. In this paper we provide the full volumetric data and 3D models for 12 scans, providing novel data on repeatability of imaging analyses and structural tracheal trait differences provided by different image segmentation methods. The volume data is provided here with segmented tracheal regions as 3D models.

Determination of Transverse Shear Stiffness of Sandwich Panels with a Corrugated Core by Numerical Homogenization.

Knowing the material properties of individual layers of the corrugated plate structures and the geometry of its cross-section, the effective material parameters of the equivalent plate can be calculated. This can be problematic, especially if the transverse shear stiffness is also necessary for the correct description of the equivalent plate performance. In this work, the method proposed by Biancolini is extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board. The method is based on the strain energy equivalence between the full numerical 3D model of the corrugated board and its Reissner-Mindlin flat plate representation. Shell finite elements were used in this study to accurately reflect the geometry of the corrugated board. In the method presented here, the finite element method is only used to compose the initial global stiffness matrix, which is then condensed and directly used in the homogenization procedure. The stability of the proposed method was tested for different variants of the selected representative volume elements. The obtained results are consistent with other technique already presented in the literature.

Numerical prediction of the stress state in CFRP induced by installing a blind rivet nut

The present paper offers a FE modeling strategy to predict the stress state in carbon fiber reinforced plastic (CFRP) plate material after installing a Blind Rivet Nut (BRN). In industry, a BRN is a permanent mechanical fastener used to equip plate material with a threaded part. Analogue to the installing process of the more common blind rivet, the BRN deforms plastically in such a way a counter head is formed on the underside of the plate. Simultaneously, the upper side of the deformation chamber expands in the radial direction creating an interference fit. The interference fit together with the counter head units the nut to the plate. However, the high contact forces between the BRN and the plate often cause damage in the CFRP material compromising the integrity of the joint. The latter observation implies that while setting a BRN in CFRP, the detrimental contact forces must be controlled to guarantee a qualitative joint. The necessary understanding of the stress distribution in the plate material is numerically investigated in two steps. In the first step, a computational efficient axisymmetric model is used to reveal the contract pressure between the BRN and the plate during the setting process. In the second step, the contact pressures are transferred to a 3D model of the plate. In this stage, the orthotropic properties of the composite are assigned to the plate material and an adequate failure criterion is adopted. The result is compared to a full 3D model using the Tsai – Wu failure criterion.

Experimental investigation and mass transfer modelling of 3D printed monolithic cation exchangers

3D printing has recently found application in chromatography as a means to create ordered stationary phases with improved separation efficiency. Currently, 3D printed stationary phases are limited by the lack of 3D printing materials suitable for chromatographic applications, and require a strict compromise in terms of desired resolution, model size and the associated print time. Modelling of mass transfer in 3D printed monoliths is also fundamental to understand and further optimise separation performance of 3D printed stationary phases. In this work, a novel 3D printing material was formulated and employed to fabricate monolithic cation exchangers (CEXs) with carboxyl functionalities. CEXs were printed with ligand densities of 0.7, 1.4, 2.1 and 2.8 mmol/g and used in batch adsorption experiments with lysozyme as model protein. All CEXs demonstrated high binding strength towards lysozyme, with maximum binding capacities of up to 108 mg/mL. The experimental results were described using mass transfer models based on lumped pore diffusion and lumped solid diffusion mechanisms adapted to reflect the complex geometry of the 3D printed monoliths. An exact 3D model as well as less computationally demanding 1D and 2D approximations were evaluated in terms of their quality to capture the experimental trend of batch adsorption kinetic data. Overall, the model results indicate that mass transfer in the fabricated CEXs is mostly controlled by pore diffusion at high protein concentrations in the mobile phase, with solid diffusion becoming important at low protein concentrations. Also, the kinetic data were approximated equally well by both the full 3D model as well as the 2D approximation, indicating leaner mathematical models of lower dimensionality can be employed to describe mass transfer in complex three dimensional geometries. We believe this work will help spur the development of 3D printable materials for separations and aid in the development of quantitative platforms to evaluate and optimise the performance of 3D printed monoliths.

Topology optimization of planar cooling channels using a three-layer thermofluid model in fully developed laminar flow problems

This paper investigates the topology optimization of planar cooling channels using a low-cost multilayer thermofluid model. A novel three-layer model including the upper/lower cover-plate layers and the central solid-fluid mixing layer is proposed. The flow boundary layer effect and the heat transfer effect in the thickness direction are modeled as the flow coupling and thermal coupling effects between adjacent layers, respectively. Particularly, in order to estimate more accurate temperature fields, the constructed three-layer heat transfer model in the solid-fluid mixing channel is derived based on the assumption of adaptive temperature profiles in the thickness direction. Further, based on the three-layer thermofluid model, the porosity field is introduced to describe the channel’s topology, and the corresponding topology optimization scheme is presented. Several optimized channels under different constraints and boundary conditions are shown and discussed in comparison. Optimized channels show streamlined boundaries and reasonable layouts and exhibit competitive heat dissipation performance. Parametric studies are conducted to analyze the effectiveness and reliability of the topology optimization scheme. Further, to evaluate the accuracy and efficiency of the proposed three-layer model, optimized channels are simulated with the full 3D model and previous low-cost models. The proposed three-layer model exhibits good consistency with the full 3D model while achieves great improvement in efficiency.