Three-dimensional Element Research Articles

Calculation of the strength of water management facilities for the sustainable development of rural areas

The physical relations are presented at the loading step of a bulk body in two variants. In the first version, the theory of plastic flow is used. In the second variant, to determine the increments of plastic deformations, a hypothesis is proposed about the proportionality of the increments of plastic deformations to the components of the deviator of stress increments, which made it more correct and easier to obtain the defining equations at the loading step. Variants of physically nonlinear defining equations in the calculation of three-dimensional elements of water management objects are implemented in the developed tetrahedral finite element with nodal unknowns in the form of displacement increments and stress increments.

Mathematical and computer simulation of semiconductor systems of various dimensions and the elements of device structures based on them

The article, in the form of a minireview, reflects the results of theoretical, and partly experimental investigations of the electrical, optical and magnetic phenomena in three-dimensional, two-dimensional, one-dimensional and zero-dimensional systems and elements of device structures made of germanium, silicon, carbon and other chemical elements carried out at the Faculty of Physics of Belarusian State University over the past 25 years.

Adaptive multi-fidelity (AMF) modelling of progressive damage in notched composite laminates

In recent years, high-fidelity simulations with discrete crack modelling techniques have been shown to accurately model the mechanics of progressive failure in composite laminates. However, these require high computational effort and are currently not practical beyond small coupon-sized specimens with a few tens of plies. In this paper, an adaptive multi-fidelity (AMF) modelling approach is proposed, wherein actively damaging areas are modelled with high-fidelity three-dimensional (3D) brick elements and discrete cracks, while dormant and inactive sites are modelled with lower-fidelity shell elements and smeared cracks. The transition criteria between the two levels of modelling are studied in order to preserve as much fidelity to the physics as necessary while improving computational efficiency. The results are benchmarked with that of high-fidelity simulations and experimental data of open-hole tension (OHT) of cross-ply and quasi-isotropic laminates in the literature.

Structures and Settlement Control of Yujingshan High-Speed Railway Tunnel Crossing Massive Rockfill in a Giant Karst Cave

The Yujingshan high-speed railway tunnel crosses a giant cavern system with a 108 × 104 m3 volume chamber and an 18 km long underground river. The massive project, which lasted three years, was eventually awarded the “Overcoming the Challenges” award by the International Tunneling and Underground Space Association (ITA) in 2020. However, since the cave chamber was filled with large-scale rockfill, structural settlement is a non-negligible problem. This paper presents the unique structures of a bridge supporting railway tracks wrapped by tunnel lining and the settlement control of the Yujingshan tunnel crossing massive rockfill in the giant cave. The geological characteristics and design considerations are systematically introduced. A three-dimensional coupling discrete element method (DEM) and finite difference method (FDM) numerical model and 13 months of long-term settlement monitoring were conducted to evaluate the settlement behavior. The results indicate that the morphology of cavern and internal deposits caused the whole rockfill to migrate to the lower left. The tunnel structure consequently developed a significant inclined settlement. The continuous construction load would increase the settlement value by 31.4%. The bottom reinforcement of steel-pipe pile with grouting could effectively inhibit settlement and differential settlement. Considering the simulation results, the tunnel bottom had greater settlement than the limit standard for high-speed railway embankment, which means this special structure form is reasonable for operation. Meanwhile, the monitoring results show that the tunnel bottom settlement in D3K279+891~D3K279+947 had not performed an apparent convergence trend after 13 months. Further structural monitoring and compensation grouting should be actively considered for operation maintenance.

Seismic performance of PVA textile cementitious composites used as permanent formwork in full-scale circular RC columns

The strength, stiffness and ductility capacity of structural systems must be protected under seismic effects. In the presence of lateral reinforcement, the confinement effect provides these critical properties to reinforced concrete (RC) structures. Textile reinforced cementitious composites (TRCC) have very good tensile, flexural and long-term performance. The effect of confinement will occur in RC columns by using these multilayer composites as permanent formwork. In addition, thanks to the permanent formworks, the service life will be extended against the drawbacks of structural defects. In this study, TRCC circular permanent formworks were manufactured by using a newly developed PPR (Pull-Pour-Roll) technique and machine. A cementitious mortar was designed and 4 & 6 layers of PVA textile were selected for the production of composite permanent formworks. The most important feature of permanent formworks is that they are hollow, thin sectioned and three-dimensional structural elements. Four full-scale circular column specimens were tested in the laboratory under the combination of constant axial load and reversed cyclic lateral load. Two of the columns were constructed as permanent formwork, while others were reference specimens built by temporary formworks. Composite formwork columns and one of the reference specimens include insufficient lateral reinforcement whereas the other reference column has adequate lateral reinforcement. This study was conducted to evaluate the effects of TRCC permanent and conventional temporary formworks in RC columns on key parameters of confinement. These parameters are respectively the hysteretic response, strength, displacement ductility, stiffness degradation, energy absorption capacity, damping ratio, residual displacement, crack pattern and failure mechanism. Extensive experimental studies have shown that the lateral load capacities, ductility, initial stiffness and energy dissipation in composite formwork columns have increased considerably compared to conventional columns. Thus, the TRCC permanent formwork increases the efficiency of confinement. Consequently, there is a great potential for use of TRCC permanent formworks as an alternative for conventional formworks in the RC columns.

Post-process hot-pressing of wood-polymer composites: Effects on physical properties

Replacing plastic with wood fibres in polymer-based products, such as façade panels, makes building more sustainable. One such bio-based material is Wood-Plastic Composites (WPC) made of wood fibres and a thermoplastic matrix. The latter enables post-process thermal forming of WPC semi-finished components. As an additive industrial manufacturing process, three-dimensional elements can be prefabricated using hot pressing technology. This could promote new building applications. However, knowledge about which essential characteristics change physical parameters to what extent is so far scarce. This study revealed that, in contrast to heating time and pressing force, the temperature causes the most significant and strongest physical changes. Extreme hot-pressing temperature resulted in 37% higher water absorption, and this was least dependent on the compound formulation. Colour, density and wettability changed differently depending on WPC composition and hot-pressing parameters. Apart from density, monitoring of colour, wettability and water absorption are suitable measures for production control as they respond most sensitively to the process. As a practical implication, product developments from hot-pressed WPC elements should consider lower temperatures and shorter heating times, whereas the pressing force hardly plays a role.

Flow control by distributed suction behind three-dimensional roughness element on the straight wing model

The paper is devoted to the close investigation of the flow over perforated suction section in the presence of the three-dimensional roughness element. Measurements were conducted over the surface of the straight wing with and without suction. It was shown that distributed suction allows diminishing the intensity of longitudinal structure. Also the boundaries of the effective suction usage were found.

Enhanced 3D solid finite element formulation for rotor dynamics simulation

In this paper, an enhanced solid finite element formulation for rotor dynamics analysis is presented. The element kinematics is first defined with a Total Lagrangian formulation in order to account for possible centrifugal stiffening effect and its associated pre-stress deformation. The novelty of the three-dimensional element proposed in this study is then to correctly consider the effect of inertia due to small rotational deformation occurring around the pre-stressed equilibrium position. The rotational motion is characterized by interpolation of the translational degrees of freedom of the element. The accuracy and convergence of the proposed finite element are tested on several numerical examples consisting of a rotating rigid disk and a rotating Timoshenko beam with different slenderness ratios. All results agree well with analytical solutions excerpted from literature and demonstrate the usefulness and applicability of the proposed finite element formulation. • Initial stress effect from centrifugal force is included. • A total-Lagrangian formulation is used. • The change of direction of the spin velocity induced by deformation is accounted for. • Results show good accuracy and convergence rate at high rotating speed.

Numerical simulation of heat transfer in the selective laser sintering process of Polyamide12

Selective laser sintering (SLS) process is the most perfect seven three-dimensional printing processes that produces three-dimensional parts from a polyamide or metal powders in stratified, the need of this process is in all different fields, the medical field, art, aerospace and other industries. The thermal phenomena generated by SLS is essential to analysis the microstructure, mechanical properties, residual stress, and all deformation of produced parts. This study applied three-dimensional element finite (EF) method by COMSOL Multiphysics software to investigate the temperature evolution in SLS. The surface heat source and the dependence of material properties on temperature are considered. It is found that the developed element finite (EF) method is able to capture the high gradients of temperature in the center of the spot laser of polyamide powder 12 (heat affected zoon). The effects of physical proprieties and laser parameters are also investigated, it was observed in the polyamide 12 powder bed, the temperature increase with the increase of pre-heating temperature and also with increasing the power laser which sintered the polyamide powder bed, the temperature increases. Also, this simulation helps us to control all the parameters and optimize the SLS process of polyamide 12, to make a perfect polyamide part manufactured by this machine with excellent quality.

Resource-environment joint forecasting using big data mining and 3D/4D modeling in Luanchuan mining district, China

The Fourth generation industrial age and 5G + intelligent communication in the "Fourth Paradigm of Science" in the 21st century provide a new opportunity for research on the relationship between mining development and environmental protection. This paper is based on the theory of metallogenic geodynamics background, metallogenic process and quantitative evaluation and chooses the Luanchuan district as a case study, using deep-level artificial intelligence mining and three/four-dimensional (3D/4D) multi-disciplinary, multi-parameter and multi-scale modeling technology platform of geoscience big data (including multi-dimensional and multi-scale geological, geophysical, geochemical, hyperspectral and highresolution remote sensing (multi-temporal) and real-time mining data), carrying out the construction of 3D geological model, metallogenic process model and quantitative exploration model from district to deposit scales and the quantitative prediction and evaluation of the regional Mo polymetallic mineral resources, the aim is to realize the dynamic evaluation of highprecision 3D geological (rock, structure, hydrology, soil, etc.) environment protection and comprehensive development and utilization of mineral resources in digital and wisdom mines, it provides scientific information for the sustainable development of mineral resources and mine environment in the study area. The research results are summarized as follows: (1) The geoscience big data related to mineral resource prediction and evaluation of district include mining data such as 3D geological modeling, geophysics interpretation, geochemistry, and remote sensing modeling, which are combined with GeoCube3.0 software. The optimization of deep targets and comprehensive evaluation of mineral resources in Luanchuan district (500 km2, 2.5 km deep) have been realized, including 6.5 million tons of Mo, 1.5 million tons of W, and 5 million tons of Pb-Zn-Ag. (2) The 3D geological modeling of geology, mineral deposit, and exploration targeting is related to the mine environment. The data of exploration and mining in the pits of Nannihu – Sandaozhuang – Shangfang deposits and the deep channels of Luotuoshan and Xigou deposits show a poor spatial correlation between the NW-trending porphyryskarn deposits and the ore bodies. The NE-trending faults are usually tensional or tensional-torsional structures formed in the post-metallogenic period, which is the migration pathway of hydrothermal fluid of the related Pb-Zn deposit. There is a risk of groundwater pollution in the high-altitude Pb-Zn mining zones, such as the Lengshui and Bailugou deposits controlled by NE-trending faults are developed outside of porphyry-skarn types of Mo (W) deposits in the Luanchuan area. (3) Construction of mineral resources and environmental assessment and decision-making in intelligent digital mines: 3D geological model is established in large mines and associated with ancient mining caves, pit, and deep roadway engineering in the mining areas to realize reasonable orientation and sustainable development of mining industry. The hyperspectral database is used to construct three-dimensional useful and harmful element models to realize the association of exploration, mining, and mineral processing mineralogy for the recovery of harmful elements (As, Sb, Hg, etc.). 0.5 m resolution Worldview2 images are used to identify the distribution of Fe in the wastewater and slag slurry of important tailings reservoirs, so as to protect surface runoff and soil pollution.

Maritime navigational assistance by visual augmentation

AbstractSeveral types of equipment have been developed over the years to assist ship operators with their tasks. Nowadays, navigational equipment typically provides an enormous volume of information. Thus, there is a corresponding need for efficiency in how such information is presented to ship operators. Augmented reality (AR) systems are being investigated for such efficient presentation of typical navigational information. The present work is particularly interested in an AR architecture commonly referred as monitor augmented reality (MAR).In this context, the development of MAR systems is briefly summarised. The projection of three-dimensional elements into a camera scene is presented. Potential visual assets are proposed and exemplified with videos from a ship manoeuvring simulator and a real experiment. Enhanced scenes combining pertinent virtual elements are shown exemplifying potential assistance applications. The authors mean to contribute to the popularisation of MAR systems in maritime environments. Further research is suggested to define optimal combinations of visual elements for alternative maritime navigation scenarios. Note that there are still many challenges for the deployment of MAR tools in typical maritime operations.

A reunião: um diálogo entre a arte e o design para gestão e criação de um produto audiovisual em meio a pandemia de COVID-19 Orlando José Dantas Lopes

This project promotes a dialogue between contemporary art, cinema and design, seeking to develop an audiovisual project using limited resources in the midst of the COVID-19 pandemic. The study starts from a creative process focused on a poetics materialized through masks designed in the form of sculptures and installations that are transmuted into three-dimensional performance elements, composing costumes and scenarios suitable for creative exploration in the scope of photography and audiovisual production. The narratives and aesthetics are designed with light and shadow effects, emptiness and filling, space and non-space concepts. The social isolation caused by the new Coronavirus is personified through sensations and experiences of color, light and darkness, creating a ritualistic atmosphere of transformation of the self, starting from the principles of belief and faith, in addition to a cycle of learning and unveiling in an obscure environment. The methodology used was based on design thinking strategies, interviews with creators and potential consumers, scriptwriting, scale, costume development, photomontages and prototyping of the proposed audiovisual product. Making a creative proposal during the social isolation proved to be a methodological, managerial, financial, technical and mental challenge, in view of the overload of activities for the team members and the difficulties generated by remote work, with decision-making that is often time-consuming and dense. This study is relevant for creators, producers, designers and visual artists interested in producing audiovisual products with a strong creative appeal and at the same time with limited resources, using methodologies focused on remote team work.

A review on PLA with different fillers used as a filament in 3D printing

Three-dimensional (3-D) printing is the method of forming a three-dimensional element by layering materials. 3-D printing is commonly done with a variety of materials such as ceramics, polymers and metals. Researchers are working to develop biodegradable additives for 3-D printing to provide sustainable additives. Biodegradable polymeric substances are taken into consideration ability 3-D printing substances because of their abundant assets and beneficial properties. Further, due to their multi-functional characteristics, they are also seen as probable contenders to replace petroleum-based polymeric materials. However, some of their properties are inferior to conventional synthetic polymeric materials. Hence, it is investigated by surveying advanced bio-waste polymer as reinforcement materials with polylactic acid (PLA) filaments for the polymer matrix in 3D printable filaments. The mechanical and thermal properties of polylactic acid filaments (PLA) with various types of fillers were examined in this review work. This overview mainly provides support for young researchers engaged in 3D printing using bio-filled composite materials in the area of PLA processing.

Analysis of delamination of composite laminates via extended finite element method based on the layerwise displacement theory and cohesive zone method

Composite laminates are being more employed as fundamental structures due to its low weight and high stiffness. To predict the material response in presence of damage can be demanding due to composite’s complex nature. Hence, superior computational models should be further investigated to speculate a more accurate composite behavior. This paper proposes an extended finite element procedure, based on the layerwise displacement theory, to simulate delamination to composite laminate. It is assumed a cohesive behavior to the damaged domain, described by a traction separation law. An extra degree of freedom associated to the strong discontinuity (delamination) is added at each layer top and bottom surface for out-of-plane displacement. This extra degree of freedom is only active on the failed nodes. To validate the model, a pre-delaminated composite analysis is performed and compared to results already reported in the literature. In addition, all stress components can be precisely calculated due to layer wise displacement field assumption, without any concern about the membrane and shear locking, not to mention its greater computational efficiency when compared to equivalent three-dimensional elements. Therefore, in the present work, it is shown the limitations and potentialities when a cohezive formulation is combined to extended finite element method using a new kind of approach. Additionally, this formulation makes easier to model delaminations using finite element method keeping a good accuracy without the need of cumbersome finite element models.

Analysis of the effect of bedding attitude on relaxation deformation characteristics of the surrounding rock of an underground powerhouse in a layered rock mass

To study the stability of an underground powerhouse in layered rock mass, a series of numerical simulations was conducted using three-dimensional distinct element code to investigate the effect of bedding attitude on the relaxation deformation characteristics of the surrounding rock of an underground powerhouse. The results showed that when the bedding dip angle was less than 30°, the maximum deformation of the surrounding rock occurred at the arch crown and bottom plate. However, when the dip angle was greater than 60°, the maximum deformation occurred at the side wall. Under the same conditions, with the increase in dip angle, the maximum deformation of the surrounding rock and the depth of the relaxation deformation zone (RDZ) increased first and then decreased, and their peak values were observed when the dip angle reached 60°–70°. With the increase in the angle between the bedding strike and longitudinal axis of the cavern, the maximum deformation and depth of the RDZ decreased gradually and stabilized when the angle was greater than the threshold. For the steeply inclined layered rock mass, when designing the underground powerhouse, the angle between the bedding strike and longitudinal axis of the cavern should not be less than 60°.

Development and application of a three-dimensional GPGPU-parallelized FDEM for modelling rock fragmentation by blast

Numerical modelling of rock fragmentation by blast is an important step to the optimum fragmentation. Combined finite-discrete element method (FDEM) has recently been proven to be one of the most promising methods for modelling the fracture and fragmentation of rocks under various loading conditions including rock blasting. However, almost all FDEM modellings of rock blasts are conducted in two-dimension. Correspondingly, this study implements a three-dimensional (3D) hybrid finite-discrete element method (HFDEM) parallelized on the basis of the general-purpose graphic-processing-unit (GPGPU) to model the fracture and fragmentation process of rock by blast. The main components of HFDEM3D include robust fracturing algorithm, efficient contact activation approach and various implementations of gas and rock interactions, which are firstly briefly reviewed here and introduced in detail in authors’ various former publications. The GPGPU-parallelized HFDEM3D is then applied to model the rock fracture and fragmentation process by the detonation of a single borehole and simultaneous and consecutive detonations of multiple boreholes.

Analysis of Longitudinal Beam Damage of a Container Chassis Semi-Trailer Using Finite Element Method – Case Study

This study investigates the damage of a container chassis loaded with a container having a capacity of 22 thousand litres. The chassis was damaged during full-load operation. Based on the observed effects of damage induced in a longitudinal beam (longeron) of the container chassis, a hypothetical course of events was elaborated. An attempt was made to recreate the actual course of events by eliminating the reasons due to which the effects of damage significantly differed from those observed post factums. To this end, numerical finite element method (FEM) simulations were performed using the Abaqus software. The damaged longitudinal beam of the container chassis was modelled using three-dimensional (3D) solid elements. It was assumed that the beam had the same profile cross-section over its entire length. In the numerical model, the container chassis had a pinned support on the fifth wheel. Elastic elements were used to model the axle-supported regions of the container chassis with the wheels. The following three events were identified as the potential causes of container chassis damage: the container chassis was supported by the bumper on the ground when the wheels on the right side were in contact with the bottom of the road surface cavity; the container chassis was supported by the bumper on the ground when the wheels on the right side were not in contact with the bottom of the road surface cavity; the bumper was subjected to point impact during vehicle reversal. The numerical results demonstrated that for each of the proposed damage hypothesis, the highest reduced stresses were located in the very region where the container chassis damage was actually observed. It was found that the observed damage was most probably induced when the container chassis was supported on the bumper and there was no contact between the wheels and the road surface due to the presence of a cavity in the road surface. Moreover, analytical calculation results demonstrated that the force acting on the structural members of the container chassis in the analysed load case exceeded the force resulting from the static load of the structure by more than 2.5 times. The load-induced stress in the beam material significantly exceeded the strength of the structure.

A novel 3D-FDEM method using finite-thickness cohesive elements to simulate the nonlinear mechanical behaviors of rocks

The crack closure stage and a high ratio of unconfined compressive strength (UCS) to tensile strength (TS) are frequently observed in laboratory tests of highly fractured rocks. However, few numerical methods can capture the crack closure behavior and high UCS/TS ratio in three dimensions. Hence, in this study, a novel three-dimensional finite-discrete element method (3D-FDEM) using finite-thickness cohesive elements was proposed, and random initial microcracks were introduced to the method. The crack closure stage and high UCS/TS ratio of highly fractured rock (Lac du Bonnet granite) are well matched through the present method. The simulated results show that the crack intensity determines the occurrence of the crack closure stage and the crack width significantly influences the evolution process of tangent modulus and crack closure strain. Due to the combination of stiffness degradation and failure of cohesive elements and initial microcrack closure, this method can capture the evolution trends of tangent modulus of various rock materials. The decreases in the simulated UCS, TS and elastic modulus with an increase in crack intensity are consistent with the experimental results of rocks after thermal treatment. A calibration procedure, which can ease the calibration of the parameters of this method, was proposed.

Nonlinear mechanics of sandwich plates: Layerwise third-order thickness and shear deformation theory

The nonlinear mechanics of sandwich plates is studied using a layerwise third-order thickness and shear deformation theory. In particular, the two face sheets are modelled using a second-order shear deformation theory (well-justified in case of a zero-shear stress only at one outer surface) and the core is modelled with a third-order thickness and transverse shear deformation theory. After introducing continuity of displacements at the interfaces between the core and the face sheets, 16 independent kinematic parameters are retained. An independent parameter is kept to describe the thickness deformation, which allows for introduction of the corresponding boundary condition; this represents a significant novel contribution. Geometric nonlinearity in all the kinematic parameters is introduced. Numerical results are presented for deflection of a sandwich plate under pressure. A thin core was considered, since it is numerically more critical, and a wide range of core stiffnesses was studied in order to verify the validity of the proposed model till the limit case of two plates joined by a core of negligible stiffness (i.e., two independent plates). Numerical results are compared to those obtained by a commercial finite element (FE) program with three-dimensional solid elements till the limit when the FE code fails for large deformations of the extremely weak core.

Optimization of design parameters of displacement isolation piles constructed between a high-speed railway bridge and a double-line metro tunnel: From the view point of vibration isolation effect

A double-line metro tunnel was constructed beneath an existing high-speed railway bridge in a city of east China. To avoid the unexpected displacement of the bridge resulting from the shield tunneling, the displacement isolation piles were employed between the shield tunnels and the pile foundation of the bridge. An accompanied optimization design issue of the isolation piles is analyzed in this work. The optimization target is not only that the displacement criteria of the bridge pile foundation during tunneling process must be met, but also an outstanding vibration mitigation effect in operation process should be achieved. In this work, a steady-state finite element analysis (FEA) is employed to evaluate the limit of the pile spacing according to the displacement criteria of the high-speed bridge. After that an analytical model and a three-dimensional (3D) finite-infinite element model of the bridge-foundation-tunnel system are established, respectively, for further optimization of the pile parameters from the view point of vibration isolation effect. The optimized pile spacing of the isolation piles for the real project case is finally recommended based on in-situ measurement data and the evaluation results.