Solid Model Research Articles

Coarse-Grained Simulation Model for Crystalline Polymer Solids by Using Breakable Bonds.

We propose a highly coarse-grained simulation model for crystalline polymer solids with lamellar structures. The mechanical properties of a crystalline polymer solid are mainly determined by the crystalline lamellar structures. This means that coarse-grained models rather than fine-scale molecular models are suitable to study the mechanical properties. We model a crystalline polymer solid by using highly coarse-grained particles, of which the size is comparable to the crystalline layer thickness. One coarse-grained particle consists of multiple subchains and is much larger than monomers. Coarse-grained particles are connected by bonds to form a network structure. Particles are connected by soft but ductile bonds to form a rubber-like network. Particles in the crystalline region are connected by hard but brittle bonds. Brittle bonds are broken when large deformations are applied. We perform uniaxial elongation simulations based on our coarse-grained model. As the applied strain increases, crystalline layers are broken into pieces and nonaffine and collective motions of broken pieces are observed. Our model can successfully reproduce yield behaviors that are similar to typical crystalline polymer solids.

Study on the influence of guardrails on the mechanical properties of pre-stressed hollow plate beam bridges structure

In order to improve the design level of pre-stressed hollow slab bridge beams, the airport 1# bridge was taken as the research object to study on the influence of guardrails on the mechanical properties of pre-stressed hollow plate beam bridges. On the basis of conducting overall structural verification, a solid model was established to analyze the influence of bridge deck guardrails on the mechanical behavior of cast-in-place joints in hollow slab bridges. Research shows that the maximum deflection and the maximum bending moment internal force decreases by 40 % and 14.5 %, respectively when taking into account the stiffness of the guardrail. However, the maximum shear force of the hollow slab edge joint and middle joint increases by 75 % and 14.5 %, respectively. The maximum shear force increases by 35.62 % when the height of the guardrail increases from 0.5 m to 2 m. The results indicate that the influence of bridge deck guardrails on the shear performance of slab hinge joints should be considered during the preliminary design stage of such bridges. The research results can provide reference for such structures.

Prediction of Particle Dynamics in Bubbling Fluidized Beds with Inertial Number-Based Drag and Solid Stress Models

Prediction of Particle Dynamics in Bubbling Fluidized Beds with Inertial Number-Based Drag and Solid Stress Models

Simulation and Analysis of Double Compound CAM Pusher Tool Changing Mechanism for NC Machine Tool

The core mechanism of existing CNC tool changers is typically a single composite cam swinging rod linkage. This setup has two main drawbacks: amplified vibration errors and high impact forces due to the swinging rod. To address these, this study focuses on CNC tool changers, specifically selecting the up-and-down motion follower and proposing a novel double composite cam push rod type mechanism. Solid modeling for both mechanisms was conducted using Creo and Matlab, and theoretical modeling of the contact forces for each follower type was completed. Comparative analysis shows the push rod follower exhibits lower contact forces than the swinging rod. Using the Adams platform, the dynamic characteristics of both mechanisms were analyzed, leading to an optimized design for the push rod type. An experimental model, scaled to 0.5, was built to compare experimental data with simulation results. The findings verify the accuracy of the models, supporting the feasibility of the push rod type tool changer.

Development of a Methodology for Obtaining Solid Models of Products That Are Objects of Reverse Engineering Using the Example of the Capstone Micro-GTU C 65

Currently, about a thousand micro gas turbine units of small and medium capacity are in operation in the Russian Federation, which are used as an autonomous power source at critical infrastructure facilities. During long-term operation, the component parts of the micro GTU may fail and require replacement or repair. The lack of spare parts and design documentation for their production makes it impossible to operate. As a way to solve the problem, the reverse engineering process can be used to produce components. One of the stages of reverse engineering is to determine the geometric parameters of the object. The fastest and most accurate way to obtain geometric characteristics in the reverse engineering process is 3D scanning. Three-dimensional scanning technology is used to obtain a solid 3D model of the prototype surface, based on which design documentation is subsequently developed. This article presents the results of a study of the influence of the parameters of the distance between polygonal grid points and the scanner exposure on the detailing of the outer surface and the geometric parameters of the resulting polygonal model. As a result of this study, the dependence of the final file size and the time spent on scanning and processing on the distance between the points of the polygonal grid and the model was established. Based on the dependence of the parameters, recommendations were obtained for choosing the distance between the points of the polygonal grid of laser 3D scanning. Also, after performing the stages of reverse engineering, the methodology for creating solid models and design documentation of parts of power equipment units using 3D scanning technology was improved.

Benchmarking of analytical photoionization models for solids using photoionization-induced reflection

Benchmarking of analytical photoionization models for solids using photoionization-induced reflection

Dynamic simulation analysis of aircraft engine planetary gear system

The Geared Turbofan (GTF) engine is used for aircraft propulsion with fan drive, characterized by its complex structure and operation in challenging environmental conditions. During its operation, variations in gear meshing and loads on the transmission shaft exacerbate vibration within the transmission system, leading to a decline in engine performance. This paper established three-dimensional solid models of the X-type aviation engine planetary gear system, input shaft, and output shaft, and employed ADAMS for multibody dynamics analysis, achieving simulation of engine operational vibrations. Modal and harmonic response analyses were conducted using ANSYS to observe and analyze critical parameters such as vibration displacement, vibration acceleration, gear meshing forces, modal resonance, and harmonic resonance, evaluating the impact of vibration amplitude, frequency, and their effects on system performance and longevity, providing guidance for vibration control and optimization of aviation engine systems.

Spatiotemporal evolutions of gas pressures in coal seam during gas extraction under mining disturbance

A 3D geometric model is established based on a fluid‒solid coupling model for purpose of identifying the influences of mining disturbances on the distribution of gas pressures in front of a working face during gas extraction. Then, the stress distribution and gas extraction process are simulated using COMSOL software. The spatiotemporal evolutions of gas pressures in front of the working face are analyzed from the dimensions of point, line, surface, and volume. A comparative analysis has been conducted to explore the distribution patterns of gas pressure in fractures and pores. The results show that under mining disturbance, the stresses in front of the working face create a stress-relaxation area, a stress concentration area, and an original stress area. Moreover, a low stress concentration is located near the boreholes. In the early stage of gas extraction, corresponding to the stress distribution, the gas pressures present a depressurization area, pressure concentration area, and almost undisturbed area. As the time increases after mining, the effects of mining disturbances gradually decrease, and the range of the gas pressure concentration area steadily shortens and shifts toward the front of the working face. Under the same temporal conditions, the gas pressure in pores is higher than that in fractures. At the onset of mining, the pore gas pressure is even greater than the initial pressure. Furthermore, during the identical extraction period, the “concentration area” of pore gas pressure is situated farther away from the coal wall of the working face compared to the “concentration area” of fracture gas pressure. These results of the study provide theoretical support for arranging drainage boreholes, enhancing gas extraction efficiency, safeguarding against gas accidents.

Three 3D graphics engineering technologies for fallow deer antlers characterization in ecology and management approaches

Numerous studies focus on creating 3D-models of biological elements for geometric evaluation using CAD tools. A crucial aspect is to obtain accurate geometrical data that is easy to obtain and cost-effective for analysis. The main objective is to evaluate the geometrical accuracy of 3D-models obtained with three graphical techniques of three-dimensional geometrical documentation that characterise the fallow deer antlers in an accurate 3D-model, which is used as input data in biological analyses estimating hunting quality, asymmetry and volume. Three technologies are evaluated: structured light scanning, multi-image photogrammetry (SfM), Structure from Motion, and spatial photogrammetric restitution using two photographs in a CAD system. The geometric accuracy of the 3D-models obtained and the deviation between relevant points of the antler structure, in the main beam, in the main tines and palm, are estimated. Subsequently, the suitability of each 3D-model is studied according to the type of biological application for which it is intended. Based on the results, solid and axial 3D-models, the applicability of the three techniques for the study of biological parameters such as hunting quality, asymmetry and volume is discussed. It concludes on the most appropriate procedure to define the digital characterisation of the antler, depending on the type of biological study to be carried out in order to obtain accurate results. Characterising a geometrically complex structure such as the fallow deer antler in a 3D-model quickly and accurately can help to quantify various biomarkers in populations of specimens, making it possible to infer internal and external influencing factors.

The Observation of Performance Trends by Numerical Simulation with Different Parameters in a Nonlinear Reversible Solid Oxide Cell System

The reversible solid oxide cell model is established by COMSOL Multiphysics® (version 5.4) software under multi-physics coupling. According to the governing equation, the simulations were conducted based on the same parameters for many control groups numerically. At the same time, a comparison of these results was involved. For the air electrode in SOFC mode, the performance of the fuel cell will increase with the increase in the porosity. For the fuel electrode in SOFC mode, the increase is much greater than the impact of the porosity. The design parameters compared in this simulation are used to simulate and analyze and predict fuel cell performance under different conditions. The design parameters related to the electrode microstructure are defined in this model as: porosity (electrode porosity), pore size (electrode internal average pore size), and permeability (electrode internal permeability).

A constitutive model for amorphous solids considering intrinsic entangling of shear and dilatation, with application to studying shear-banding

A constitutive model for amorphous solids considering intrinsic entangling of shear and dilatation, with application to studying shear-banding

In situ blockade of TNF-TNFR2 axis via oncolytic adenovirus improves antitumor efficacy in solid tumors.

Tumor necrosis factor (TNF) has been recognized as an immune activation factor in tumor immunotherapy. Our study demonstrated that TNF blockade markedly enhanced the antitumor efficacy of oncolytic adenovirus (AdV) therapy. To minimize systemic side effects, we engineered a recombinant oncolytic AdV encoding a TNF inhibitor (AdV-TNFi) to confine TNF blockade within the tumor microenvironment (TME). AdV-TNFi significantly improved therapeutic outcomes across various solid tumor models, including four murine and two golden hamster cancers. Immune cell profiling identified CD8+ T cells as the primary mediators of AdV-TNFi-induced antitumor effects, rather than CD4+ T or NK cells. Additionally, AdV-TNFi significantly decreased the infiltration of suppressive myeloid-derived immune cells within the TME and promoted long-term antitumor immune surveillance. Further investigation indicated that TNFR2, more than TNFR1, is pertinent to the immunosuppressive TME, with a recombinant AdV encoding anti-TNFR2 demonstrating comparable antitumor efficacy to AdV-TNFi. Moreover, AdV-TNFi enhanced the antitumor efficacy of gemcitabine and immune checkpoint blockades (ICBs), such as anti-PD-L1 and anti-TIGIT antibodies, in pancreatic carcinoma, and the anti-EGFR antibody in colon carcinoma. In conclusion, intratumoral blockade of the TNF/TNFR2 axis using AdV augments cancer immunotherapy efficacy while mitigating the risks associated with systemic TNF or TNFR2 suppression, warranting further clinical investigation.

Intraspecific variation in root system structure in a Pinus thunbergii stand grown in a gravelly spit coast.

ABSTRACT Root systems of Pinus thunbergii planted in coastal forests exhibit high phenotypic plasticity under edaphic conditions. The objectives of this study were as follows: 1) to determine intraspecific variation in root system traits, maximum root depth and length of horizontal roots of P. thunbergii in a gravelly spit within a stand by excavation of entire root systems, and root system structure modelling from photographs; and 2) to determine whether the root system traits can be inferred from aboveground traits. The P. thunbergii trees grew twisting roots through the hard soil layer of sand and gravel and exhibited variation in root systems; most individuals had inherent tap root systems, but one had a two-tiered thick horizontal root system with a thinner tap root. Although the maximum length of the horizontal root had no relationship with the aboveground traits, the maximum root depth of P. thunbergii was significantly related to tree height. This suggests that tree height can be a predictive indicator of root depth, which is valuable for the rehabilitation of disaster-resistant coastal forests. Both surface and solid models of root system were produced using structure-from-motion with a multi-view stereophotogrammetry method, which enabled continuous estimation of the sum of the root cross-sectional area at any depth in the depth direction. The new method of reconstructing root system models was effective for post-analysis of traits after excavation. We concluded that intraspecific variations in the root system traits of P. thunbergii were observed even at the stand level on a gravelly spit coast.

Structure and Strength Optimization of the Bogdan ERCV27 Electric Garbage Truck Spatial Frame Under Static Loading

Taking into account the requirements to reduce the release of harmful emissions into the environment, the EU’s environmental standards when transitioning to the Euro 7 standard in 2025 will actually lead vehicles having to operate without producing emissions in all driving situations. Carmakers believe that the new, much stricter regulations will mark the end of the internal combustion engine era. For example, in 2030, the manufacturer SEAT will cease its activities, leaving behind the Cupra brand, which will be exclusively electric in the future. This trend will apply not only to private vehicles (passenger cars), but also to utility vehicles, which is the subject of our research, namely the spatial tubular frame in the Bogdan ERCV27 garbage truck, presented in the form of a solid model. The peculiarity of the studied model is the installation of a battery block behind the driver’s cabin, causing an additional load to be placed on the spatial frame of the garbage truck, which in terms of its architecture is more like the body of a bus. During the conditions involving various modes of operation of a full-scale Bogdan ERCV27 garbage truck sample, questions about the strength and uniformity of its load-bearing spatial frame inevitably arise, which are decisive, even at the stage of designing and preparing the technical documentation. The main static load mode, which, despite its name, also covers dynamic conditions, was modeled using the appropriate coefficient kd = 2.0. The maximum stresses on the model during the “bending” mode were 381.13 MPa before structure optimization and 270.5 MPa as a result of the improvement measures. The spatial frame mass was reduced by 4.13%. During the “torsion” mode, the maximum deformation values were 12.1–14.5 mm, which guarantees the normal operation of the aggregates and units of the truck.

Y2T2O7-Based Pyrochlores As Alternative Materials for Diffusion Barrier Layer at the Fuel Electrode-Electrolyte Interface in SOFC/SOEC

The introduction of a ceria-based diffusion barrier layer between electrolyte and Sr-containing oxygen electrode is a common approach to avoid the formation of undesirable low-conducting SrZrO3 phase at the electrolyte/electrode interface with negative effects on the performance of solid oxide cell (SOFC/SOEC). However, partial reduction of cerium cation to 3+ oxidation state under reducing conditions induces noticeable chemical expansion of doped ceria ceramics and may cause delamination of the ceria-based buffer layer applied at the fuel electrode side of solid oxide cell. The present work explores pyrochlore-type Y2Ti2O7-based titanates as alternative interlayer materials operating at the interface between the electrolyte and Sr-containing fuel electrodes. A- and/or B-site Y2T2O7-based compositions including (Y0.9Ca0.1)2Ti2O7, (Y0.85Ca0.15)2Ti2O7, (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7, (Y0.9Ca0.1)2(Ti0.9Mn0.1)2O7, (Y0.9Mg0.1)2Ti2O7, and Y2(Ti0.9Mg0.1)2O7 were selected as candidate materials. The materials were prepared by solid reaction method and sintered at 1600-1700°C in air. The characterization included structural and microstructural studies, controlled-atmosphere dilatometry, and measurements of electrical transport properties (electrical conductivity as a function of temperature and oxygen partial pressure by AC impedance spectroscopy, oxygen-ion transference numbers by modified EMF method). The results showed that the solubility of calcium cations in the yttrium sublattice is limited to 10 at.%. Apart from (Y0.9Ca0.1)2Ti2O7, only (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7 and (Y0.9Mg0.1)2Ti2O7 were phase-pure pyrochlores, while other materials contained different types of secondary phases. Total electrical conductivity of single-phase ceramics in air increased in the row (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7 < (Y0.9Mg0.1)2Ti2O7 < (Y0.9Ca0.1)2Ti2O7 reaching 0.02 S/cm at 800°C (Fig.1). The conductivity is predominantly oxygen-ionic at intermediate oxygen pressures, while minor contributions of p-type and n-type electronic transport increase under oxidizing and reducing conditions, respectively. Average oxygen-ion transference numbers under air/(10%H2-N2) gradient at 800°C were 0.995 for (Y0.9Ca0.1)2Ti2O7 and 0.983 for (Y0.9Mg0.1)2Ti2O7. Pyrochlore-type titanate ceramics showed moderate thermal expansion coefficients, 10.2-10.4 ppm/K, under both oxidizing and reducing conditions at 25-1100°C and negligible chemical expansion. On the contrary, gadolinia-doped ceria Ce0.9Gd0.1O2-δ ceramics underwent a substantial chemical expansion and cracking on heating above 700-800°C in 10%H2-N2 atmosphere. (Y0.9Ca0.1)2Ti2O7 was selected as the preferred interlayer candidate material with the highest ionic conductivity. A procedure for the fabrication of a thin interlayer in a model electrolyte-supported button cell was developed. Chemical compatibility was verified in contact with solid electrolyte, yttria-stabilized zirconia, and model fuel electrode materials, Sr0.85Pr0.15TiO3-δ and SrFe0.75Mo0.25O3-δ. Figure 1. Electrical conductivity of pyrochlore-type Y2T2O7-based ceramics in air. Acknowledgments: This work was done within the scope of project CLEARNESS (funded by the ERA-MIN3 program), project SFRH/BD/150704/2020 (funded by the FCT), and project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds through the FCT/MCTES (PIDDAC), Portugal. Figure 1

Fractional order models of viscoelastic polymeric solids undergoing large deformations

We present a fractional order model for nonlinear visco-hyperelastic solids taking into account large deformations. A three-field form of the Hu-Washizu principle is introduced to create a stable finite element method in the context of nearly incompressible dynamics. The β-method (a generalized midpoint rule) for time discretization is implemented into a variational finite element framework for efficient computing of numerical approximations to the initial boundary-value problem for hyperbolic equation of motion. Finally, a 2-D cantilever beam problem with a step end load is considered in order to demonstrate the algorithm.

Thermodynamically consistent modeling of viscoelastic solids under finite strain

The present article is concerned with modeling the viscoelastic behavior of Polydimethylsiloxane (PDMS) in large-strain regime. Starting from the basic principles of thermodynamics, an incremental variational formulation is derived. Within this model, the free energy density and dissipation function determine elastic and viscous properties of the solid. The main contribution of this paper is the estimation of the parameters in the proposed phenomenological model from measurements conducted on Sylgard184 samples. This non-linear material model simplifies to a Prony-series representation in frequency domain in case of small deformations. The coefficients of this Prony-series are detected from dynamical temperature mechanical analysis measurements. Time-temperature superposition allows to combine measurements at different temperatures, such that a sufficiently large frequency range is available for subsequent fitting of Prony-parameters. A set of material parameters is thus provided. The incremental variational formulation directly lends itself to finite element discretization, where an efficient and stable choice of elements is proposed for radially symmetric problems. This formulation allows to verify the proposed model against experimental data gained in ball-drop experiments.

Conforming embedded isogeometric analysis for B-Rep CAD models with strong imposition of Dirichlet boundary conditions using trivariate B++ splines

Strong imposition of Dirichlet boundary conditions for immersed finite element methods or immersed isogeometric methods remains a challenge. To address this issue, this paper presents a 3D conforming embedded isogeometric method for Boundary-Represented (B-Rep) solid CAD models by generalizing our bivariate B++ splines to trivariate B++ Splines. The proposed method can convert a B-Rep model into a trivariate B++ spline solid patch with body-fitted boundary representation while retaining key features of B-rep models, such as sharp points, sharp edges, and holes. The basis functions of the trivariate B++ spline solid patch satisfy the Kronecker delta property, which implies that we can strongly impose Dirichlet boundary conditions on B-Rep models without the necessity of Nitsche's method. The presented method can be viewed as a parameterization method that inherits the advantages of volumetric parameterization methods in that the basis functions of a reconstructed geometry satisfy the Galerkin method. In addition, compared with T-splines, the proposed method does not generate the extraordinary point and can achieve optimal convergence rate. Several numerical examples are used to demonstrate the reliability of the presented method.

Micropapillary structure: A natural tumor collective invasion model with enhanced stem-like properties.

Cancer stem cells aggregate to form clusters, which have enhanced stem-like properties and metastasis potential. However, the molecular mechanisms underlying the formation of cancer stem cell cluster-like structures with acquisition of stronger invasion and metastasis abilities remain unclear. Micropapillary carcinoma (MPC) is a subpopulation of small, merulioid, inverted, nonfibrous vascular clusters floating in the stroma present in a range of solid malignant tumors and characterized by frequent vascular/lymphatic vessel invasion and lymph node metastasis. Our results showed that these cell clusters exhibit a stem cell phenotype, supporting the premise that MPC may serve as a promising solid tumor model for studying invasion and metastasis of cancer stem cell clusters. In this review, we discuss the latest advances in MPC research and targeted therapy, focusing on analysis of their stem-like characteristics, mapping their multiomics characteristics, and elucidating the vascular and immune microenvironment of MPC. The existing MPC organoid model was employed to explore potential breakthroughs in targeted therapy and immunotherapy for cancer stem cell clusters.

ON THE MODELING OF BOUNDARY CONDITIONS IN THE PROBLEM OF DETERMINING THE NATURAL FREQUENCIES OF A PIPE

The article discusses the issues of modeling boundary conditions for calculating the natural frequencies of a cylindrical straight pipe based on finite element models. For this purpose, various types of models were used, including rod (Pipe), shell (Shell) and solid (Solid). The study examines various options for implementing the conditions of hinged and rigid fastening: at two points, four points, along the middle surface of the pipe for the Shell model, along the end surface or along part of the outer surface of the pipe for the Solid model. The results of the study showed that the Pipe model provides a better approximation to the analytical solution. For the Shell and Solid models, when hinged, the best option for limit conditions to get closer to the analytical results is to fasten on each edge of the pipe at two points through which the neutral line of the cross-section of the pipe passes during bending. For rigid fastening, the results obtained from the Shell model are closest to the analytical solution if the fastening is carried out at four points or along the line of the middle surface of the pipe. For the Solid model, fastening along the end or part of the outer surface of the pipe is most effective. An analysis of the vibration modes showed that under different fastening conditions vibration modes arise that are associated with the deformation of the pipe as a shell. An assessment of the convergence of the obtained results was given, which confirmed the adequacy of the finite element models. The conclusions from the study made it possible to determine effective ways to set boundary conditions for the Shell and Solid models, which is also confirmed by the preliminary experimental studies of the authors. To obtain clearer results when determining the natural frequencies of pipeline systems, it is recommended to use experimental research methods along with numerical ones. The results obtained are of practical importance for solving problems of design and resource assessment of pipeline systems in various fields of industry.