Three-dimensional Analysis Method Research Articles

Automatic scaled boundary finite element method for three-dimensional elastoplastic analysis

This paper introduces an automatic way of performing 3D static and dynamic elastoplastic analyses in the framework of the scaled boundary finite element method (SBFEM), which only requires the boundary discretization and thus can provide high flexibility in automatic mesh generation. The input models in this paper are described by Standard Tessellation Language (STL) format due to its simplicity and popularity in computer-aided design. The automatic mesh generation from any input geometry is achieved by utilizing the octree decomposition algorithm and boundary trimming. An efficient approach for 2D static image-based elastoplastic analysis based on SBFEM is extended to 3D static and dynamic elastoplastic analyses in this present work. In this improved approach, the return mapping algorithm is only required to be performed at the scaling center of each subdomain in the yield zone. Constant elastoplastic constitutive matrix and internal stresses are used within each yielded subdomain as well. This will greatly simplify the implementation of elastoplastic formulation and reduce the costs involved in the elastoplastic analysis as the return mapping algorithm is computationally expensive. Meanwhile, stabilization matrix is also introduced in the elastoplastic stiffness matrix to eliminate the spurious modes. Numerical examples are presented in this paper to show the feasibility and accuracy of the proposed approach as well as its capability of modelling complex structures in practical applications.

Effect of oblique incidence on the optical engine of extinction ratio

The optical engine (OE) is the core component of a projection optical system. The extinction ratio (EO) directly affects imaging contrast. A three-dimensional EO calculation and analysis method, based on traditional EO theory, is proposed to obtain the optimal incidence angle range and solve the problem of ignoring the oblique incidence’s influence on the EO’s existing research process. The method is simulated and verified by LightTools. Results show that, when the incident azimuth half angle is less than4.7∘, and the spatial half angle is less than180∘, the EO is 0.016, distribution is uniform, and the stray light is effectively suppressed.

Three-dimensional morphological analysis of cervical foraminal stenosis using dynamic flexion-extension computed tomography images

BackgroundMorphological features of foraminal stenosis in cervical spondylotic radiculopathy and the adequate extent of facet resection in posterior cervical foraminotomy remain uncertain. Herein, we evaluated quantitatively foraminal widths in cervical spondylotic radiculopathy on dynamic flexion-extension computed tomography using a novel three-dimensional analysis method and determined the extent of facet resection in posterior cervical foraminotomy. MethodsSeventeen patients undergoing posterior cervical foraminotomy for cervical spondylotic radiculopathy were evaluated. A neuroforamen three-dimensional model was built from preoperative images of flexion-extension computed tomography myelography, and an ordinary cervical spine coordinate system and an original neuroforaminal coordinate system, were established. In the neuroforaminal coordinate system, minimum areas perpendicular to the long axis by the slices from inlet to outlet of neuroforamen and narrowest foraminal width in a slice of minimum area were measured. The location of the narrowest region from inlet of the foramen was calculated. Ratios of minimum and sufficient facet resection were obtained from the location of the narrowest region in the neuroforaminal coordinate system. ResultsThe narrowest foraminal widths (flexion/extension) in the cervical spine coordinate system and the neuroforaminal coordinate system were 2.9/2.3 and 2.6/1.9 mm, respectively. The mean values of the location of the narrowest region (flexion/extension) were 0.27/0.22 and 0.50/0.45 mm, respectively, and the narrowest region in the neuroforaminal coordinate system was located on the outer side than in the cervical spine coordinate system (p < 0.001). The ratios of minimum and sufficient facet resection were 23 ± 8% and 32 ± 9%, respectively. ConclusionsThe narrowest regions both in flexion and extension are located at the middle of the foramen based on the neuroforaminal coordinate system. Ordinary evaluation of axial computed tomography images likely underestimates the extent of facet resection, whereas certain extent of facet resection does not exceed 50% in cases with single-level cervical spondylotic radiculopathy. Study designA retrospective case control study.

The combination of two-dimensional and three-dimensional analysis methods contributes to the understanding of glioblastoma spatial heterogeneity.

Heterogeneity is regarded as the major factor leading to the poor outcomes of glioblastoma (GBM) patients. However, conventional two-dimensional (2D) analysis methods, such as immunohistochemistry and immunofluorescence, have limited capacity to reveal GBM spatial heterogeneity. Thus, we sought to develop an effective analysis strategy to increase the understanding of GBM spatial heterogeneity. Here, 2D and three-dimensional (3D) analysis methods were compared for the examination of cell morphology, cell distribution and large intact structures, and both types of methods were employed to dissect GBM spatial heterogeneity. The results showed that 2D assays showed only cross-sections of specimens but provided a full view. To visualize intact GBM specimens in 3D without sectioning, the optical tissue clearing methods CUBIC and iDISCO+ were used to clear opaque specimens so that they would become more transparent, after which the specimens were imaged with a two-photon microscope. The 3D analysis methods showed specimens at a large spatial scale at cell-level resolution and had overwhelming advantages in comparison to the 2D methods. Furthermore, in 3D, heterogeneity in terms of cell stemness, the microvasculature, and immune cell infiltration within GBM was comprehensively observed and analysed. Overall, we propose that 2D and 3D analysis methods should be combined to provide much greater detail to increase the understanding of GBM spatial heterogeneity.

Structure Optimization of Battery Module With a Parallel Multi-Channel Liquid Cooling Plate Based on Orthogonal Test

Abstract In order to keep the power battery work within an ideal temperature range for the electric vehicle, the liquid cooling plate with parallel multi-channels is designed, and a three-dimensional thermal model of battery module with the liquid cooling plate is established. Subsequently, the effects of the cooling plate thickness and the cooling pipe thickness, channel number and coolant mass flow rate on the cooling performance of battery modules are analyzed. The results show that four parameters of the cooling plate have an important role in the thermal behavior of the liquid-cooled battery system. It is not good to improve the performance of the cooling system by changing only certain parameters. The four factors discussed above are optimized by using orthogonal test according to the univariate analysis. With the use of the orthogonal test, the optimization model obtained is obviously enhanced in the aspect of maximum temperature control and temperature uniformity of liquid-cooled battery module. Results show that the three-dimensional thermal analysis and orthogonal test method are compatible with optimal design of liquid-cooled battery modules.

A New 3D Method for Reactor Core Vibration Based on Silicon Steel Lamination Rules and Application in UHV Shunt Reactors

A new three-dimensional (3D) analysis method is proposed as the existing two-dimensional (2D) method has low accuracy in analysing the vibration characteristics of oil-immersed shunt reactors, such as ultrahigh-voltage (UHV) shunt reactors. First of all, a set of 3D laminated coordinate systems was defined based on silicon steel lamination rules, in which the anisotropy of magnetic properties for laminated silicon steel in the rolling direction (RD), the transverse direction (TD), and the lamination direction (LD) were considered. Then, the mapping between laminated coordinate systems and space rectangular coordinate system was established to unify the parameters in different laminated coordinate systems. With the mapping, the anisotropy of the magnetic properties in the laminated coordinate systems was transformed into a rectangular coordinate system. Next, two sets of comparative studies between the new 3D method and the traditional 2D method were carried out, which show that the 3D method has high precision and a wide application range. Finally, the relationship between air gap number and core vibration of UHV shunt reactors was studied by the new 3D method. The results show that, as the number of air gaps increases, the magnetic flux density and the total force area of Maxwell force are increased, resulting in the intensification of core vibration. The conclusions of this paper are helpful for the design of large oil-immersed reactors.

Seismic wave input method for three-dimensional soil-structure dynamic interaction analysis based on the substructure of artificial boundaries

The method of inputting the seismic wave determines the accuracy of the simulation of soil-structure dynamic interaction. The wave method is a commonly used approach for seismic wave input, which converts the incident wave into equivalent loads on the cutoff boundaries. The wave method has high precision, but the implementation is complicated, especially for three-dimensional models. By deducing another form of equivalent input seismic loads in the finite element model, a new seismic wave input method is proposed. In the new method, by imposing the displacements of the free wave field on the nodes of the substructure composed of elements that contain artificial boundaries, the equivalent input seismic loads are obtained through dynamic analysis of the substructure. Subsequently, the equivalent input seismic loads are imposed on the artificial boundary nodes to complete the seismic wave input and perform seismic analysis of the soil-structure dynamic interaction model. Compared with the wave method, the new method is simplified by avoiding the complex processes of calculating the equivalent input seismic loads. The validity of the new method is verified by the dynamic analysis numerical examples of the homogeneous and layered half space under vertical and oblique incident seismic waves.

Modeling and Stability Analysis of Aerially Towed Systems Using Geometric Computational Dynamics

This paper presents a method for three-dimensional simulation and analysis of circularly towed cable–body systems with nontrivial coupling between the attitude dynamics of the towed body and the cable. By application of a Lie group variational integrator, a compact and singularity-free geometric model that maintains its accuracy even for extremely long-time simulations with aggressive maneuvers is developed. Coupling the integrator to a nonvariational model of the towing airplane is also discussed. By employing a variation-based linearization technique, a geometric linear system that is used to investigate the mode shapes and the coupling between the motion of the cable and the attitude dynamics of the towed body is obtained. A distributed parameter model is developed separately that describes the equilibrium configurations of the circularly towed system, the results from which are used to evaluate those of the geometric numerical integrator. For the case of towing a bisymmetric finned body, it is observed that reducing the flight path radius leads to a limit cycle, due to the interactions between the rolling motion of the body and the pendulum mode of the cable.

A Three-Dimensional Discontinuous Deformation Analysis Method for Investigating the Effect of Slope Geometrical Characteristics on Rockfall Behaviors

In the present study, a three-dimensional discontinuous deformation analysis (3D DDA) method was developed and used to investigate the effect of slope geometrical characteristics on rockfall behaviors. The slope geometrical characteristics of rockfall, such as the slope height, slope angle and slope shape, were summarized, and the corresponding calculation models were proposed. The algebraic computation and contact mechanics of the three-dimensional (3D) global contact theory were illustrated and implemented into the 3D DDA method. The accuracy of the developed 3D DDA method was verified through the four basic movement forms of rockfall: freefalling (oblique projectile), sliding, rolling and bouncing. Numerical examples were performed to study rockfall behaviors under different slope geometrical characteristics by analyzing the kinetic energy or velocity conversion, motion trajectories, and damage degree and range of moving blocks. The results demonstrate that the 3D DDA method can accurately simulate rockfall movement, which is significantly affected by slope geometrical characteristics. Furthermore, some suggestions for slope excavation and protection were put forward.

Three-Dimensional Tolerance Analysis Modelling of Variation Propagation in Multi-stage Machining Processes for General Shape Workpieces

The quality control of general shape workpieces has become one of research hotspots because of the increasing diversity of products. The theory of stream of variation (SoV) for machining processes is a successful method in researching variation propagation rule. However, with the consideration of all key elements in manufacturing system, there is no unified and integrated model for workpieces in different kinds of shapes. In this paper, a new variation propagation model in multi-stage machining processes for general shape workpieces is established. It visually demonstrates the variation propagation chain and expands the universality of current SoV models. The connection of all key elements in manufacturing system is defined as an assembly chain, in which the variations are defined and propagated by modified three-dimensional tolerance analysis method. The equivalent conversion of the connection between workpiece and fixture realizes the modelling of general shape workpiece regardless of its machining method and locating scheme. Real experiments validate the effectiveness and accuracy of the new SoV model for different shape workpieces. This model has great potential to be applied toward multi-scale variation modelling, process control, and fault diagnosis for general shape workpieces.

An extended state space method for three-dimensional elasticity analysis of arbitrary graded sandwich plates

A novel procedure, within the framework of the state space method in linear elasticity, is proposed for three-dimensional analysis of simply supported, multi-layered plates including any number of arbitrary graded layers at arbitrary locations along the transverse coordinate. First, the conventional state space method used for single layer exponentially graded plates is extended to multi-layered plates including any number of exponentially graded layers. This is achieved by incorporating additional matrices for implementing continuity of the state variables at interfaces involving at least one exponentially graded layer. Further, a piece-wise exponential model is used to extend the procedure to plates that include any number of layers whose material properties vary as arbitrary smooth functions along the transverse coordinate. Comparisons with existing elasticity and approximate solutions show that the method is capable of providing numerical results with better accuracy for all the cases studied. New results are obtained for three-dimensional deformation analysis of sandwich plates with graded face sheets and graded soft core, including a detailed parametric study.

Simplified 3D model for the uplift analysis of liquid storage tanks

Vertical uplifting of the tank base is perhaps the most relevant characteristic of the seismic behaviour of unanchored cylindrical liquid storage tanks made of steel. When an unanchored tank is subjected to lateral loads due to the earthquake-induced hydrodynamic pressures, a portion of the base plate tends uplift locally. Analysis of the base plate uplifting of unanchored tanks implies many sources of nonlinear behaviour mechanisms such as the varying contact of the base plate with the foundation, large deflections, the material yielding and the plastic rotation of the base plate. This paper presents a comprehensive analysis of the partially uplifted base plate of two thin-walled cylindrical tanks (one slender and one broad). First, a nonlinear quasi-static cyclic analysis with a finite element model and a simplified model is carried out for each tank. Next, an efficient method for three-dimensional dynamic analysis is proposed and used in order to obtain the nonlinear time history response of each tank. The simplified non-linear model proposed in this paper was capable to provide a good estimation of both the rocking resistance of the liquid-loaded base plate and the stress distribution on the tank wall in contact with the foundation. A set of seven seismic ground motions was used for the time history analysis. Finally, the distribution of the tank wall stresses and the critical responses of the tanks are discussed. Both anchored and unanchored tanks may present a high compressive axial stress due to the seismic effect.

Application of 3D-DDA integrated with unmanned aerial vehicle–laser scanner (UAV-LS) photogrammetry for stability analysis of a blocky rock mass slope

In stability analysis of discontinuity-controlled slopes, the rationality of results is related to the accuracy of three-dimensional (3D) slope morphology and the reliability of the discontinuity survey. With the advent of remote sensing technologies for engineering geological surveys and slope stability analyses, step-change increases have been made in the quality of data available and geometrical characterization of rock slopes. Although these techniques are frequently employed in the characterization of slope geometry and joint surfaces at present, limited research has been undertaken to effectively process the derived data and improve the quality in the reconstruction of slope geometry imported into 3D discontinuous numerical models. In this paper, an integrated system coupling 3D-DDA and UAV-LS photogrammetry is presented as a tool to evaluate the stability of a blocky rock mass slope. The system includes a UAV-LS module, a modeling module, a block-generation module, and a 3D-DDA calculation module. In the UAV-LS module, the use of UAV-LS system integrated with field mapping and site observations allows the acquisition of detailed outputs (point clouds) on both the slope and discontinuity geometry. An effective combination of commercial software Geomagic and Hyperworks is used in the modeling module to process oceans of 3D point cloud data and construct complex 3D geometrical models based on reverse engineering. In the block-generation module, the three-dimensional discontinuous deformation analysis (3D-DDA) method is then carried out in order to simulate the movement of potentially unstable blocks, within which an independent block-cutting algorithm is used to generate the blocks with arbitrary shapes and the finite structural planes similar to the real cases. The 3D-DDA calculation module uses 3D-DDA calculation algorithm to derive the simulation results. The capability of the proposed system for stability analysis of a jointed slope is demonstrated by a practical example.

Research on the Effect of Tree Barriers on Rockfall Using a Three-Dimensional Discontinuous Deformation Analysis Method

On rockfall slopes, trees can play a natural and efficient protective role in preventing the occurrence of rockfall disasters. This paper presents a study on the tree barrier effect on rockfall based on a three-dimensional discontinuous deformation analysis (3D DDA) method. The tree barrier effect on rockfall is studied considering the 3D spatial effect of rockfall movement and the 3D spatial distribution of trees. The basic movement forms and collision modes of rockfall related to the tree barrier are classified, and the impact factors of tree arrangements on rockfall are proposed. The contact mechanism employed in the 3D DDA method is illustrated, and the accuracy of the 3D DDA rockfall simulation is verified by comparing with the results obtained from laboratory experiments. Numerical examples are conducted to study the effect of the tree barrier on rockfall, and general laws are derived by analyzing the variation of kinetic energies and motion trajectories of moving blocks. The results show that the 3D DDA method can effectively predict the 3D motion behaviors of rockfall and assess the tree barrier effect. Furthermore, a reasonable arrangement of trees or a combination of protective facilities and trees can prevent or mitigate the rockfall hazards.

Evaluation of the trueness and precision of eight extraoral laboratory scanners with a complete-arch model: a three-dimensional analysis

PurposeThe purpose of this study was to evaluate the trueness and precision of eight different extraoral laboratory scanners using three-dimensional (3D) analysis method. MethodAn arch-shaped master model was designed with a computer software (Rapidform XOR2) and manufactured with a 3D printer (Projet 3510 MP). Then the master model was digitized with an industrial 3D scanner (ATOS Core 200). With each scanner master model was scanned ten times and stereolithography (.stl) data were imported into 3D analysis software (Geomagic Control). Accuracy was determined with evaluating trueness and precision. ResultsTrueness of the scanners were 27.5 μm for 7 series; 30.9 μm for D640; 26.8 μm for D710; 33.3 μm for Activity 102; 32.4 μm for Tizian Smart-Scan; 21.6 μm for NeWay; 26.1 μm for inEOS X5 and 17,47 μm for D2000. 28.2 μm for laser; 32.9 μm for white light and 21.7 μm for blue light scanners. Significant differences were found between scanners (p < .001), (p < .001). Precision of the scanners were 30.1 μm for 7 series; 31.7 μm for D640; 26.3 μm for D710; 22.7 μm for Activity 102; 25.1 μm for Tizian Smart-Scan; 15.7 μm for NeWay; 26.1 μm for inEOS X5; 16.6 μm for D2000. 29.2 μm for laser; 24.4 μm for white light and 19.2 μm for blue light scanners. Significant differences were found between scanners (p < .001), (p = .027). ConclusionsThe systems that had the best combination of trueness and precision for complete-arch scanning were D2000 and NeWay. Scanners using blue-light showed more accurate results than the white-light and laser scanners.

Evaluation of one-piece polyetheretherketone removable partial denture fabricated by computer-aided design and computer-aided manufacturing

To explore a novel method for fabricating removable partial dentures (RPDs) using polyetheretherketone (PEEK) by computer-aided design and computer-aided manufacturing (CAD/CAM) technologies and to evaluate their fits for different assemblies in vitro. A standard stone cast of mandibular partial edentulous jaw was scanned using a lab scanner. Based on the digital cast, thirteen complete RPDs were designed combing dental CAD software and reverse engineering software, and then fabricated using PEEK by milling machine. Fits of assemblies were evaluated quantitatively by measuring the spaces between RPDs and casts. The gaps between RPDs and stone casts in different assemblies were duplicated using light-body silicone impression material and then measured using three-dimensional (3D) digital analysis methods in virtue of a dedicated software. Statistically, one-way analysis of variance (ANOVA) was used to compare the difference of gaps among assemblies in different shapes such as occlusal rest, denture base, and major connector. Paired-samples t test was used to compare the gaps difference for the similar shape assemblies in different areas. One-piece PEEK RPDs were successfully designed and fabricated by CAD/CAM, and all the RPDs were well-seated on stone casts. The gaps between occlusal rests and casts [(84.3±23.6) μm] were significantly larger than those of denture bases [(32.5±27.8) μm] and major connectors [(49.9±47.0) μm], which meant that the fits of denture bases and major connectors were better than that of occlusal rests. However, the fits of all assemblies could be accepted clinically. For the similar shape assemblies in different areas, there were no significantly differences for gaps between distal extension denture bases [(25.1±55.3) μm] and non-extensive denture bases [(41.5±17.7) μm]. The gaps of occlusal rests adjacent and nonadjacent to the edentulous space were (86.1±29.8) μm and (80.8±42.1) μm respectively and there were no significantly difference between them either. These results implied that different locations had no apparent effect on the fits of assemblies. With the computer-aided design and computer-aided manufacturing technology, PEEK can be used to fabricate one-piece removable partial dentures. And all assemblies of the one-piece PEEK RPDs showed satisfying fits in vitro, indicating a promising clinical application in the future.

Aerodynamic Design and Off-design Performance Analysis of a Multi-Stage S-CO2 Axial Turbine Based on Solar Power Generation System

Solar energy is an inexhaustible source of clean energy. Meanwhile, supercritical carbon dioxide has excellent characteristics such as easy access to critical conditions, high density, and low viscosity, making it one of the most popular circulating working fluids in solar power generation technology. However, solar power generation systems are severely affected by geographical distribution, seasonal variations and day-night cycles. Therefore, efficient and adaptable turbine design is the key to realize supercritical carbon dioxide solar power generation technology. In this paper, the initial thermodynamic design of 10 MW S-CO2 three-stage axial turbine is completed by self-developed thermodynamic design software, and the key thermodynamic and structural parameters are obtained. The optimal design of turbine and its aerodynamic performance at rated operating conditions are obtained by using a three-dimensional aerodynamic numerical analysis and optimization method. At last, nine off-design conditions are analyzed in detail. The results show that the designed turbine output power is 10.37 MW and the total-total efficiency is 91.60%. It can operate efficiently and steadily in the range of output power from 16.2% to 155.9%. It can adapt to the variable operating conditions of solar power generation system and meet the design requirements.

A polyhedral scaled boundary finite element method for three-dimensional dynamic analysis of saturated porous media

This paper presents a polyhedral scaled boundary FEM (SBFEM) to investigate three-dimensional seismic response of saturated porous media. The displacement interpolation functions and the pore-pressure interpolation functions are derived using enhanced SBFEM. The spatial discretization formula of generalized Biot equations is achieved by Galerkin method, and subsequently solved via time-domain solving approach. The proposed method can be applied directly over arbitrary polyhedron and octree grids, possessing desirable flexibility in investigating complex geometries and high-efficiency in discretization, which makes it more versatility for engineering simulation compared to traditional numerical methods. The reliability and advantages of the developed method are validated using three numerical examples.

Numerical and experimental study of phase-change temperature controller containing graded cellular material fabricated by additive manufacturing

The improved phase-change temperature control can be obtained by the rational graded cellular design as the thermal conductivity enhancer. 3D printing as an advanced manufacture technique provides a possibility to fabricate the integrated structure with precisely defined complex geometric architecture including the graded cellular structure, which is changing the design profoundly. In this paper, a three-dimensional numerical analysis method is proposed for the integrated phase-change temperature controller simultaneously containing internal graded cellular material and external packaging structure fabricated by additive manufacturing. In the numerical model, the two-equation model considering the phase change process is employed to describe the heat transfer of internal graded cellular material filled with the paraffin wax and the thermal conduction equation is used to calculate the temperature field of the external packaging structure. In addition, the direct couple strategy in the solving process is adopted by setting the same temperature at the interface. The experiment is carried out in order to verify the effectiveness of the numerical model. The measured temperatures under the different heating powers are all in good agreement with ones by the numerical model, which indicate that the experimental and numerical results are reliable. The parameter analysis shows that the distribution of porosity in the cellular material and the wall thickness of packaging structure have a significant influence on phase change process, and the heat transfer performance of thermal controller should be improved by the collaborative design of the internal cellular material and external packaging structure.

Image analysis for morphology, rheology and degradation study of railway ballast: A review

The performance and deformation of ballast bed are significantly influenced by the particle morphology (size and shape), the rheology (translation and rotation), and the degradation (breakage and abrasion). Regarding the ballast particle morphology, the ballast particle size is generally measured by sieving and described with the Particle Size Distribution (PSD), while the particle shape is normally classified as three characteristics, the form, angularity, and surface texture. Quantifying particle morphology with current manual methods is difficult to obtain accurate results (often subjective). Concerning the ballast particle rheology, almost all the related studies are based on numerical simulations, e.g. the Discrete Element Method (DEM). A limited number of studies were performed to record the translation and rotation with the electronic devices embedded in ballast layer. However, the numerical simulations can only precisely reflect the ballast particle rheology in quasi-static tests (e.g. direct shear test), and the electronic devices can only record the ballast particle rheology in the limited areas, where they were placed. The ballast breakage could be evaluated by the change of the PSD, but the determination of PSD involves significant errors. Additionally, the manual methods could not fully quantify the ballast abrasion. As a result, more accurate evaluation methods need to be developed and utilised for the validation and confirmation of the degradation-related studies.Towards these limitations, the studies on two-dimensional (2D) and three-dimensional (3D) image analysis methods for granular materials are reviewed, discussing their existing and potential utilisation in railway ballast applications. This paper can be of interest to the researchers, who are dealing with the performance and deformation of ballast bed. Additionally, a special attention can be paid to utilising the image analysis for accurate particle morphology quantification, particle rheology investigation and ballast degradation evaluation.