Numerical Finite Element Analysis Research Articles

A Stope Mining Design with Consideration of Hanging Wall When Transitioning from Open Pit Mining to Underground Mining for Sepon Gold Mine Deposit, Laos

This study investigates the transition from surface to underground mining at the Sepon Gold mine. The stability of surface slopes is assessed prior to commencing underground operations. Stope mining is adopted based on ore body characteristics and geological features. Finite element numerical analysis, employing the Generalized Hoek–Brown criterion, evaluates slope stability for surface slopes and opening stopes. The pit design comprises a 70° slope angle, 20 m height, and 10–15 m safety berm, meeting stability requirements with a factor of safety of 2.46. Underground mining design includes a 62° ore body dip, a 50 m thick crown pillar to prevent surface subsidence, and 5 m wide, 5 m high stopes. Sill pillars are left for support after each level of excavation. Rock bolts are employed in specific stope areas where necessary, with continuous monitoring for surface deformation. This study analyzes the influence of stope sizes on the pit wall and pit bottom stability, identifying slope failures near the hanging wall close to the pit bottom during underground mining. A slight increase in the displacement zone is observed on the upper crest of the top footwall. Overall, the findings demonstrate successful stability in the transition from surface to underground mining at the Sepon Gold mine.

Effects of Volute Structure on Energy Performance and Rotor Operational Stability of Molten Salt Pumps

A double-volute molten salt pump with two outlet pipes is proposed based on the original pump model. A numerical approach coupling finite element analysis and computational fluid dynamics (CFD) is implemented to investigate the operational stability and energy performance of two molten salt centrifugal pumps for high-temperature molten salt. The entropy production of the single-volute and double-volute molten salt pumps is investigated. The effects of the volute structures on the mechanical behavior of the impeller and shaft are considered. According to the findings, the local entropy production in the molten salt pump is dominated by the local pulsating entropy production (Spro-T), with the double-volute scheme achieving reduced energy loss. A visualization of the flow field and the local entropy production rate (LEPR) distributions indicate that the LEPR is positively correlated with the complexity of the flow, and higher levels of turbulence intensity lead to greater LEPR. The double-volute scheme enhances the complexity of the flow in the impeller, resulting in an increase in the LEPR compared with the single-volute design. However, the LEPR in the whole double-volute molten salt pump is reduced compared with the single-volute design. It is discovered that the double-volute molten salt pump experiences a less radial hydraulic force. Although the double-volute design has a slightly higher maximum equivalent stress on the impeller than the single-volute scheme, the rotor deformation is significantly less. In general, the double-volute scheme reduces energy loss and ensures better structural stability.

Numerical Analysis and Experimental Study on Seismic Coupling Response of Pipe-Soil System Under Bidirectional Seismic Excitation

The seismic response of buried pipeline is significantly affected by the soil around the pipeline. In this study, a numerical analysis model of the pipeline and the soil around the pipeline is built, and the finite element numerical analysis of its seismic response law is conducted to address the problem of pipeline soil seismic coupling response. A shaking table test of the seismic response of buried pipeline under two-way seismic excitation is performed based on the developed two-way layered shear continuum model soil box. The peak strain response at the middle section of the pipeline grows fastest, the peak strain of the pipeline under non-uniform seismic excitation constantly exceeds that under uniform excitation, and the axial strain of the pipeline exhibits more sensitivity to earthquake than the bending strain, as indicated by the results of numerical analysis and shaking table test. The peak value of soil acceleration response under non-uniform excitation exceeds under uniform excitation. The displacement of soil increases with the height. The pipeline soil interaction becomes more intense under non-uniform excitation, and the relative movement between pipeline and soil becomes more significant. The seismic excitation more significantly affects the axial displacement of soil. The peak value of soil acceleration response varies from larger along the pipeline to larger along the axis with the increase of the loading grade. A slight difference exists between the peak value of axial and transverse acceleration response of the pipeline. The peak value of pipeline acceleration response declines in the axial direction than the peak value of soil acceleration response, whereas it rises in the transverse direction than the peak value of soil acceleration response, especially under non-uniform excitation. As revealed by the above results, the effect of bidirectional non-uniform seismic excitation on the lateral pipeline soil interaction is enhanced, and soil is more seriously damaged.

Improvement of melting performance in a longitudinal finned latent heat thermal energy storage unit

AbstractThis article presents an analysis and enhancement of the charging behavior of a double‐pipe LHTES unit with longitudinal fins for concentrated solar power applications using a finite element numerical analysis approach. The finite element approach is applied to this numerical analysis by using “COMSOL Multiphysics” software. The investigated LHTES system has an operating temperature range of 180°C‐300°C and uses “DelcoTerm Solar E 15” as the heat transfer fluid (HTF) with a eutectic inorganic mixture of sodium nitrite and sodium nitrate as the phase change material (PCM). While also taking into account the impact of the tube material and the number of fins, the primary goal of this study is to evaluate performance improvement by changing the thickness and number of fins in a linked manner without changing the storage unit capacity. The results show a maximal impact on thermal performance which decreased the melting time by 46% and the charging time by 49.6% for the configuration with a fin thickness of 1 mm, 27 longitudinal fins, an inner tube made of aluminum, and a mass flow rate of 60 kg/h.

Study on the Influence of an Under-Crossing Parallel Double-Line Shield Tunnel on the Existing Tunnel Structure

Extra care should be taken when new tunnels pass through an existing tunnel. If it is not handled properly, this will affect the operation safety of the existing line, and bring security risks to the train’s operation. In order to study the impact of an under-crossing parallel double-line shield tunnel on the existing shield tunnel structure, the influence of tunnel construction on the deformation of overlying strata was analyzed, and the formula for estimating the formation settlement at depth Z below the surface, caused by the excavation of a double-tunnel parallel tunnel, was deduced. Then, a series of three-dimensional finite element numerical simulations were carried out. We analyzed and systematically studied the adverse effects of the tunnel structure of Guangzhou subway Line 5, caused by the tunneling of subway Line 18, evaluated its structure and operational safety, and provided suggestions for site construction. This research demonstrates the following conclusions. (1) The tunnel structures of subway Line 5 and Line 18 are mainly in the strongly weathered argillaceous siltstone stratum, and lightly weathered argillaceous siltstone stratum, respectively, and the stratum where the Line 18 tunnel is located is relatively safe. (2) According to three-dimensional finite element numerical simulation analysis, during the shield-tunneling process of subway Line 18, the maximum X horizontal displacement, the maximum Y horizontal displacement, and the maximum Z vertical displacement of the tunnel structure in subway Line 5 are 1.09, 3.50, and 4.55 mm, respectively. It is considered that the impact of the shield-tunnel penetration of subway Line 18 on the tunnel structure of subway Line 5 is relatively controllable, and does not affect the structure and operational safety. (3) It is suggested that settlement monitoring should be strengthened within the range of 12 m (about 1.5 tunnel diameter D). before and after the excavation axis of the underpass tunnel, and it is necessary to carry out local reinforcement treatment, to prevent adverse effects on the operation of the existing tunnel.

Study on Pressure Reconstruction Method of Explosion Shock Wave

Shock waves are one of the primary damage parameters of an ammunition explosion. Therefore, accurately obtaining the shock wave pressure distribution law after ammunition explosion is greatly significant for the ammunition damage power evaluation and the guidance of ammunition selection in the operations course. This study established the mapping function between the surface reflected and free-field shock wave pressures, considering the altitude effect on shock wave pressure. Finite element numerical simulation analysis of typical (trinitrotoluene) TNT explosive quality and static explosion shock wave pressure test were performed, and the model calculation accuracy was verified by using the obtained shock wave pressure data. The Validation results show that the model had 84% calculation accuracy and could well reflect the explosion shock wave pressure distribution law. Furthermore, the results provided a new calculation method and scientific data support for the accurate evaluation of the damage power of an ammunition explosion. Additionally, the results are significant for applications in engineering testing and the military.

Applicability analyses on the end-bearing capacity of gravity installed anchors in clay

As an efficient solution for deepwater moorings, gravity installed anchors (GIAs) have many attractive attributes and play a remarkable role in various deepwater applications. The end-bearing capacity factor offers an efficient method to evaluate GIA end bearing under complex conditions involving multiple factors. It can also assess total anchor bearing capacity. Based on numerous large deformation finite element (LDFE) analyses, two formulas have been developed to calculate the end-bearing capacity factors for GIAs in clay under quasi-static or dynamic conditions. Through rigorous statistical analysis, it is demonstrated that the formulas provide accurate predictions of the end-bearing capacity for various GIAs, particularly those with loading characteristics similar to OMNI-Max anchors, i.e., the padeye location and the loading angle. The contribution of the end bearing to the overall bearing capacity of GIAs is analyzed under various loading conditions. Furthermore, a comparative study proves that the formula accounting for the loading rate effect can be degenerated to evaluate the end-bearing capacity factor of the anchors under quasi-static conditions. The results provide a comprehensive understanding of the end bearing and offer an efficient solution for determining the total bearing capacity of various GIAs in clay under complex conditions. These findings contribute to the advancement of design and performance assessment of GIAs, enhancing their reliability and effectiveness in applications.

Evaluating interfacial bonding quality of multilayered structure based on ultrasonic testing technology

An ultrasonic evaluation method of interfacial bonding quality from layered structures is proposed for enhancing the testing accuracy. The ultrasonic reflection and transmission characteristic is theoretically analyzed, which focus on the different quality of the single and double bonding interface with spring-type. The reflection coefficient and transmission coefficient mathematic models, which include multiple parameters, are derived from the transfer matrix. Taking the first, second, and the double bonding interface as the research objects, respectively, two types of resonant frequencies have been presented by numerical solving the model, namely, the first type resonance frequency (RFI) and the second type resonance frequency (RFII). The results show that the interval of the RFⅠ is related to medium thickness of the maximum acoustic impedance. Similarly, the interval of the RFⅡ depends on other layers’ thickness. In addition, the transmission coefficient shows a change in different trends with the bonding interface gradually tending to rigid. When the adhesive layer thickness is sufficiently small compared with the wavelength, the reflection coefficient shows many local minima points at a certain frequencies range, the frequency of local minimum point increases with the increase of the stiffness coefficient. The experimental results are in good agreement with the numerical solution results and finite element analysis results.

Far-field identification of ice loads on ship structures by radial basis function neural network

The ice load is an environmental load that dominates the ice-resistant design of polar ship structures, and field measurement of ice-induced strains is an important approach to obtain ice loads. Constrained by narrow spaces and watertight structures in the ship-ice interaction area, the monitoring area where strain sensors are mounted sometimes has to be arranged separately from the loading area, which makes the classical influence coefficient matrix method no longer applicable. The far-field identification method for ice loads, based on the radial basis function neural network (RBFNN) with a simple structure and fast convergence, provides an alternative way to solve this problem. The potential mapping relationship between ice loads and far-field ice-induced strains is effectively established based on a generalised RBFNN. The influence of noise on the identification results of the ice loads on the bow shoulder of RV Xue Long 2 is thoroughly studied with finite element numerical analysis and effectively eliminated by noise injection learning algorithm. Under weak strain response and low signal-to-noise ratio, the accurate results of the subsequent scale model test indicate the possibility of engineering application. According to the rationality analysis of the identification results based on full-scale data, the applicability of the RBFNN method to field measurements is verified.

Behavior of a Composite Steel Decking and Boarding System in Fire Based on Large-Scale Experimental Testing and Numerical Modelling

This paper presents experimental and numerical results of an investigation into the thermal and structural behaviour of an innovative modular structural steel system, which includes cellular beams, that was tested in a 1-h standard fire scenario while loaded. The modular system consists of a 5.66 × 3.8 m rectangular steel frame, with a profiled steel sandwich decking (SD) system attached, which comprises of (a) profiled steel decking, (b) fibre cement, and (c) calcium silicate boards and strips. The SD system is suspended from the underside of the horizontal structural members to provide inherent fire protection to the steel beams from the bottom and acts as the load-bearing component of the flooring. The purpose of the experiment was to determine the fire resistance of the structural system, whilst under load, which is primarily based on the fire resistance of the SD system. Temperature data for the SD system was collected during the experiment and used to validate a numerical finite element analysis model. This study shows that the SD system was able to achieve a fire resistance rating of 57 min in the experiment which was governed by insulation resistance. A lower fire resistance rating is estimated based on numerical models. Structural resistance was maintained throughout the test. During preliminary testing structural collapse was observed in a separate experiment which highlights how the system is sensitive to damage to the ceiling boards. Numerical results highlight that thermal bowing and movement may result in changes in thermal interactions between adjacent elements. This paper provides novel large-scale experimental data on a loaded flooring system in fire.

Effect of blank size on impact hydroforming of 2195 Al-Li alloy half-tube part with curvature

Aluminum-Lithium (Al-Li) alloy has excellent properties such as low density, high elastic modulus and high specific strength, and it is considered as the most ideal structural material in aerospace. However, due to the low plasticity of Al-Li alloy at room temperature, it is easy to crack during cold forming, so its application and development have been limited. In order to explore the possibility of improving the plasticity of 2195 Al-Li alloy at room temperature, a half-tube part with curvature and deep cavity structure was formed by using impact hydroforming (IHF) technology. In this paper, the process route of half-tube part was optimized and four sizes of blank were designed. Through finite element numerical simulation and analysis, it was found that the F area was prone to wrinkle defects when there was less material at the inner arc position, and the most serious thinning occurred in the design margin area. After analysis and comparison, the blank size with drawing ratio of 2.22 was finally selected. Based on the verification experiment, it was found that due to the material properties of Al-Li alloy and the characteristics of IHF, one-step forming was difficult, and the forming of half-tube part was prone to insufficient drawing depth or large area fracture; Although the part obtained by two-step forming also had cracks, the overall forming quality of the part would not be affected because they were located in the design margin area to be removed later. In addition, it was observed that the surface quality of the part removed the design margin area were free of wrinkles and cracks, which meets the objective design requirements.

Study of the Behavior of the AL 2017-A Aluminium Plate Corroded and with Horizontal Cracks Treated by the Technique of Composite Materials

Abstract This work presents a comprehensive study consisting of two aspects: a numerical analytical aspect and a laboratory experimental aspect. The numerical study was a three-dimensional finite element numerical analysis of performance of corroded and horizontally cracked aluminium plates, which were repaired by composite patching. The effect of the composite types on the variance of the damaged area of the adhesive (FM-73) and their efficiency on the stress intensity factor were studied. In the experimental study, corroded aluminium plates were prepared and repaired them using technology of the composite. The results showed that the panels that were repaired with composite (boron/epoxy) give values of stress intensity factor (KI) and damaged area ratio (DR) less than the other two studied composites (glass/epoxy and graphite/epoxy), and increase the ultimate strength of plates damage, and this leads to the conclusion that (Boron/epoxy) increases the performance and durability of (Al 2017-A) plates.

Analysis of the Mechanical Properties and Study of Influential Factors of Different Materials in Tape Spring

This paper analyzes and calculates the mechanical properties of composite tape spring structures during folding and bending and establishes a non-linear control equation for the folding and bending of composite laminate tape spring structures. Accurate expressions for folding and bending displacements are obtained. The influence of the cross-section’s central angle and the composite tape spring’s ply thickness on their mechanical properties are analyzed. Finite element numerical analysis is performed on [−45 45]s laminated composite tape springs, and the correctness of the theoretical derivation is proved by comparing the curvature radius-bending moment curve. Based on previous research, the mechanical properties of different tape spring materials and structures are compared, further studying the lightweight design of space deployment mechanisms. The results show that the steady-state bending moment performance of composite tape springs is excellent, with a 162.1% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs. Additionally, the critical bending moment performance of negative Poisson ratio honeycomb structure tape springs is also excellent, with a 62.3% improvement in steady-state bending moment performance per unit mass compared to traditional metallic tape springs.

Hysteresis performance of section steel reinforced concrete-filled rectangular stainless steel tubular columns

Due to high bearing capacity and excellent seismic performance, the section steel reinforced concrete-filled rectangular steel tube has been widely applied in engineering. The application of stainless steel for outer steel tube can improve the durability performance of members. In this study, ABAQUS software was used to perform nonlinear seismic analysis on section steel reinforced concrete-filled rectangular stainless steel tubular columns, and the numerical model was validated against experimental data. The mechanism and parametric study of the hysteresis performance were conducted. These parameters mainly include: concrete strength, strength of stainless steel, strength of section steel, steel ratio of stainless steel tube, steel ratio of section steel, axial compression ratio, and slenderness ratio. The analysis results showed that: increasing the strength of stainless steel tube and concrete can significantly improve the bearing capacity of members, but the strength of section steel has little effect; the bearing capacity decreases with the increasing slenderness ratio; when the axial compression ratio is smaller than 0.4, increasing axial compression can improve the bearing capacity. The strength of each material shows little influence on the shape of load–displacement skeleton; the axial compression ratio presents high effect on the shape of descending stage of curve, and the larger the axial compression ratio, the steeper the descending stage; the slenderness shows high influence on curve shape, and the larger the slenderness, the less the elastic stiffness, and the more gentle the descending stage of curve. Finally, a simplified load–displacement hysteretic model was proposed, which exhibits good agreement with finite element numerical analysis.

Permeation grouting in soils: numerical discussion of a simplified analytical approach

Permeation grouting – injections at low-pressure values of either microfine cements or chemical products – is frequently adopted to increase the mechanical/hydraulic properties of soils, and standard design approaches are currently either empirical or based on simplified analytical solutions. In this paper, some fundamental hypotheses of these analytical solutions are discussed by carrying out a campaign of finite-element numerical analyses, in which the injection phase in a water-saturated soil is analysed, a Newtonian rheology for the grout is implemented and the hypothesis of immiscibility for the two liquids is assumed. The effect of injection source geometry is discussed, as well as the role of gravity and capillarity. The authors analyse the conditions, in terms of injection flow rate, grout viscosity, soil intrinsic permeability and retention curve, under which the analytical solutions provide reliable results. The numerical results have been compared with the simplified analytical solution herein derived for a one-dimensional spherical geometry, in terms of the ‘characteristic curves’ for the system: the relationship between injection pressure/grout front advancement and injection time.

Thermal Conductivity of Polyvinylidene Fluoride Films with a Multi-Scale Framework.

The orientation of amorphous regions in pure polymers has been noted to be critical to the enhancement of thermal conductivity (TC), but the available reports are still rather few. Here, we propose to prepare a polyvinylidene fluoride (PVDF) film with a multi-scale framework by introducing anisotropic amorphous nanophases in the form of cross-planar alignments among the in-planar oriented extended-chain crystals (ECCs) lamellae, which show an enhanced TC of 1.99 Wm-1 K-1 in the through-plane direction (K⟂) and 4.35 Wm-1 K-1 in the in-plane direction (K∥). Structural characterization determination using scanning electron microscopy and high-resolution synchrotron X-ray scattering showed that shrinking the dimension of the amorphous nanophases can effectively reduce entanglement and lead to alignments formation. Moreover, the thermal anisotropy of the amorphous region is quantitatively discussed with the aid of the two-phase model. Superior thermal dissipation performances are intuitively displayed by means of finite element numerical analysis and heat exchanger applications. Moreover, such unique multi-scale architecture also results in significant benefit in the improvement of dimensional stability and thermal stability. This paper provides a reasonable solution for fabricating inexpensive thermal conducting polymer films from the perspective of practical applications.

Investigating seismic behavior of a modified widened flange beam-column connection in SMRF utilizing experimental, numerical and hybrid simulation

This manuscript presents the seismic performance of a modified widened flange beam-column connection in a special moment-resisting frame (SMRF). The beam-column connection has been modified by two cover plates welded to the top and bottom flanges of the beam and investigated under earthquake acceleration. One-story one-bay special moment resisting frame with an increased beam flange at the vicinity of column was analyzed in accordance with the Iranian Code of Practice for Seismic Resistance Design of Buildings (Standard 2800). Experimental investigation was carried out in which a cyclic displacement history was applied. Numerical finite element analysis was carried out using ABAQUS and its results validated by experimental test results. A hybrid simulation was conducted utilizing OpenSees as the finite element software, OpenFresco as the middleware and LabVIEW as data collector and actuator motion controller. Results comparison of three above mentioned methods (experimental test, numerical analysis and hybrid simulation) indicate that the hysteresis curves are in great compatibility with each other. As expected, results demonstrate that the yielding occurred immediately beyond cover plates at arc shaped areas of beam. On the other hand, the experimental and numerical results show that the specimen reached at least 0.07 rad drift angle before experiencing strength degradation. Furthermore, parametric studies on ‘c’ and ‘R’ which are two key parameters of modified widened flange beam represent that for a constant dimensions of cover plate, increasing ‘c’ and decreasing ‘R’ will reduce plastic strain and stress demands in beam.

Numerical simulation analysis of the rolling process based on the particle swarm hybrid algorithm

ABSTRACT It is very complicated to study the three-dimensional deformation of metal during rolling. The conventional finite element numerical analysis method generally adopts a fixed algorithm to calculate the whole rolling process. This method consumes huge computing power and sacrifices some computing accuracy. In this paper, according to the characteristics of different rolling stages, on the basis of considering the degree of metal deformation, a particle swarm hybrid algorithm with adaptive weight-learning factor is proposed.The Zoutendijk algorithm, Rosen algorithm, Wolfe algorithm and particle swarm hybrid algorithm are used to numerically simulate the rolling transverse thickness distribution. The accuracy of the rolling model and the particle swarm hybrid algorithm are verified. The influence of work roll edge contact and asymmetric roll bending on the deformation of rolling metal is analysed based on particle swarm mixing algorithm.

Designable mechanical properties of modified body-centered cubic lattice materials

Lattice materials possess broad application potential in many engineering fields due to their excellent mechanical properties. In this paper, a thorough investigation is carried out for the lattice materials with the generalized body-centered cubic (BCC) cell geometry. The investigated geometry variations include (1) adding additional reinforcement bars along several cell edges, and (2) offsetting the central vertex of the cubic cell that the oblique beams connect. The influences of the cell geometry on the stiffness, the Poisson’s ratio, the energy absorption capacity and the deformation pattern of the generalized cubic lattice are ascertained through extensive theoretical and finite element (FE) numerical analyses. The results indicate that adding reinforcement bars along the loading direction can effectively enhance the stiffness and strength, but does not significantly change the deformation pattern as depicted by the shape of shear bands. The additional bars perpendicular to the loading direction can largely influence the Poisson’s ratio, making it possible to approach unity. It is found that a modified BCC lattice with properly offset central cell vertices achieves an optimal energy absorption capacity that is about 2.26 times of traditional BCC lattice. This work could provide a comprehensive reference for the mechanical properties of the most generalized BCC lattice materials.

Numerical simulation of thermal effects in laser diode end-pumped solid-state lasers utilizing finite element method

Based on the finite element numerical analysis method, the temperature field distribution in the crystal with time is simulated by using the PDE-tool in MATLAB. The critical factors affecting the crystal transient temperature distribution are simulated and analyzed. According to the simulation parameters and results, a simplified method for solving the transient heat conduction equation is proposed. The transient thermal focal length is solved to obtain its distribution expression and an approximate analytical solution. The results provide a theoretical basis for the thermal analysis process of suppressing or utilizing the transient thermal effect in high-energy solid-state lasers.