Maximum Equivalent Stress Research Articles

Tailoring of functionally graded spheres using a uniform stress condition

Homogeneous and isotropic thick spheres loaded with constant internal and/or external pressures can not be economically designed because the maximum equivalent stress is a local value. It was analytically demonstrated that, by neglecting the body loads, a functionally graded material (FGM) may be characterized in linear static analyses by two material constants: Young's modulus E(r) and Poisson's ratio ν(r). If these two functions are both known, the solution of the problem, displacement and stress distributions may be relatively easy obtained. For the inverse problem, in which a desired stress combination distribution is imposed, finding of E(r) and ν(r) is more difficult, if such a solution exists. More than that, if the solution exists, it is not unique, because two unknown functions are involved. For ν(r) = const., analytical solutions are available for E(r), but only for two particular stress conditions. In this paper, the inverse problem is solved iteratively using a finite element model and an algorithm of stress uniformization developed by the authors of this paper is proposed. In this original approach, the existing solutions were reproduced as a verification and afterwards new solutions were obtained for the remaining classical theories of resistance. The new obtained solutions were also verified by using the analytical solutions of the direct problem.

Fatigue life prediction for bottom hole assembly with defects based on drillstring dynamics analyses

Fatigue is the main cause of drilling tool fracture. Accurate prediction of drilling tool fatigue life is challenging in drilling engineering. In this study, a drillstring dynamic model was established based on the finite element (FE) method, and the dynamic response of Bottom Hole Assembly (BHA) is obtained by numerical solution. Then the Mises equivalent stress of BHA was obtained using the fourth strength theory. Combined with Walker model, the fatigue life of drillstring with initial defects was predicted. The model was first verified by reproducing the experimental data. Then, the BHA dynamic characteristics were obtained and the effects of weight on bit (WOB), rotational speed, stabilizer (STB) location and crack size on the drillstring fatigue life were discussed. Results show that, increase in rotational speed leads to a small increase in the fatigue life below the neutral point. Decrease in WOB significantly prolongs the fatigue life, and adding STB can decrease the maximum equivalent stress and increase the drillstring fatigue life near the bit. The BHA fatigue life decreases as the size of initial crack increases. When the crack size increases to a critical value, the fatigue life tends to be stable and drilling tool may break instantly. This study could provide important guidance for drilling engineers in designing BHA.

Preliminary design and thermo-mechanical analysis of the ECRH equatorial launcher focusing mirror (M1) towards the CFETR

The Electron Cyclotron Resonance Heating (ECRH) Equatorial Launcher (EL) is under research towards the China Fusion Experimental Tokamak Reactor (CFETR). In the latest pre-research model, 6MW of electromagnetic waves would be guided to the plasma by two focusing mirrors (M1 & M2) and one front plate steering mirror (SM). Since the M1 will experience intense heat generation from ohmic dissipation and neutronic irradiation, a specific water-cooling structure has been designed for it to reduce the thermal deformation, allowing the M1 to experience less mechanical pressure during long pulses. The simulation demonstrates that water can efficiently dissipate ∼0.3 kW of neutronic heat and ∼30 kW of ohmic loss heat. As a result, the maximum deformation and equivalent stress are less than 0.4 mm and 160 MPa, respectively, which satisfactorily meets the system requirements.

Experimental Studies on the Strength of a Flatcar during Shunting Impacts

The increasing demand for container transportation makes it necessary to equip the wagon fleet with appropriate flatcars in good technical condition. The study deals with the determination of the strength of the flatcar during shunting impacts using the finite element method. The flatcar model 13-401 modernized with fixed fittings for securing containers on the frame was used as a prototype. The authors determined the fields of the maximum equivalent stresses in the bearing structure of a flatcar. The strength calculation was made in SolidWorks Simulation. It was found that, during a shunting collision, the maximum equivalent stresses to the flatcar were about 418 MPa and they were concentrated in the fixed fittings. The strength was also studied using the method of electric strain gauging. The research included different impact speeds. The test results showed that the maximum difference between the stresses obtained theoretically and experimentally was 17.0%. The strength model of the flatcar was tested using the Fisher criterion. The study demonstrated that the damage to the bearing structure of the flatcar and containers could be reduced when applying an improved interaction diagram.

Computational Analysis of the Influence of Residual Stress on the Strength of Composites with Different Aluminum Matrices and Carbide Particles

A numerical study of the mechanical behavior of aluminum matrix–carbide particle composites subjected to combined thermomechanical loading is carried out. The composite structure, corresponding to that observed experimentally, is explicitly taken into account in the calculations. The mechanical response of the aluminum matrix and carbide particles is described using the isotropic elastic–plastic and elastic–brittle models. A fracture criterion of the maximum equivalent stress acting in the local regions of volumetric tension is used to study the crack initiation and propagation in the particles. The dynamic plane stress boundary value problems of cooling and tension of the composites are solved by the finite element method ABAQUS/Explicit. The influence of the cooling-induced residual stress and thermomechanical properties of the matrix and particle materials on the strength of the composites is investigated. A positive or negative effect of the residual stress is found to depend on the ratio between the particle strength and the matrix yield stress. Compressive residual stress formed in the particle after the cooling increases the strength of composites with hard matrices and low-strength particles. A decrease in the matrix–particle interfacial curvature results in a change in the fracture mechanism from in-particle cracking to debonding, which increases the composite strength. Composite elongation upon the fracture onset decreases with the volume fraction of the particles.

Numerical study on the start-up strategy of cylindrical tubular receiver filled with nickel foam

A cylindrical tubular receiver filled with nickel foam (CTRNF) appears to be a promising receiver concept due to its capability to provide temperatures over 900 °C at a high pressure. Nevertheless, CTRNF is challenged by the unsteadiness and high intensity of radiant flux may cause inaccurate start-up time predictions, providing unrealistic and unstable outlet temperatures. In this article, these matters are addressed by a numerical model coupling the Monte Carlo ray tracing (MCRT) method and discrete coordinate (DO) radiative transfer model. The model considers the cold, semi-cold, semi-hot, and hot start-up strategies on the CTRNF using N2 and Ar as the working medium. Three preheating methods and their influence on the thermal characteristic of the CTRNF are proposed. Temperature and equivalent stress distribution of internal heat absorber is simulated and analyzed. The results indicate that the duration for four start-up strategies takes 1711 s, 2189 s, 1212 s and 1032 s as the outlet temperature reaches to 1200 K, respectively, when Ar is used as the working medium (10 g/s) and radiative power of 10.5 kW incidents on the solar receiver. Compared with the 68.44 kg Ar consumption of cold start-up strategy, the Ar working medium consumption decrease by 24.44 kg, 51.68 kg, and 63.16 kg for semi-cold start-up, semi-hot start-up, and hot start-up strategy. However, the maximum equivalent stress of the CTRNF under the hot start-up strategy is 100 MPa higher than under the cold start-up strategy, which requires accurate monitoring of the cavity temperature in solar receiver.

Investigation of the Strength of a Chain Binder for Securing a Wagon on the Railway Ferry Deck

The article presents the results of the strength analysis of the chain binder components for symmetry fixing a wagon on the railway ferry deck, taking into account the actual hydrometeorological conditions of the navigation area. The simulation of the wagon dynamic load during the railway ferry rolling was carried out to determine the loads acting on the chain binder. The strength of the chain binder hook was analysed. The calculation results showed that the maximum equivalent stresses in the hook occur in the radial part and exceed the allowable ones by 23%. Therefore, to ensure the strength of the chain binder, it is necessary to comply with the appropriate roll angles of the railway ferry or create measures to reduce its load when rolling. The conducted studies will contribute to ensuring the safety of wagon transportation by sea and increasing the efficiency of rail-ferry transportation.

Mechanical Behavior of Gas-Transmission Pipeline in a Goaf

To solve the safety hazard of a buried gas pipeline caused by subsidence of a mined-out area, a three-dimensional model of a buried pipeline in a mined-out area was established using geological parameters and the finite-element software ABAQUS. The effects of the friction coefficient of the pipe and soil, the coal-seam dip angle, and the horizontal angle on the mechanical behavior of the pipe under varying widths of goaf area were investigated. The results indicate that the maximum equivalent stress of the pipeline is negatively correlated with the horizontal angle. Concerning longitudinal mining, the pipeline exhibits a high-stress zone when the mining length is >200 m, the surface displacement appears in a small range when the mining length is 40 m, and the stratum displacement range increases gradually with the increase in the mining length. When the width of the goaf is constant, the maximum equivalent stress of the pipeline is positively correlated with the tube-soil friction coefficient and negatively correlated with the coal seam dip angle. The position of maximum stress gradually tends to appear near the uphill side of the coal seam, with an increase in the coal seam dip angle.

Analysis of strength and eigenfrequencies of a steel vertical cylindrical tank without liquid, reinforced by a plain composite thread

A study of the effect of a plain composite wrapping on the stress-strain state of the wall of a steel cylindrical tank is proposed, without taking into account the liquid. The stress assessment in the tank wall was carried out based on finite element modeling of the structure’s three-dimensional model deformation. Two tank wall variants were modeled: with constant and variable thickness, as well as three wrapping variants: with one, double and triple intervals, where the mechanical characteristics of the tank thread and material of different types were considered, taking into account the oil filling level, the wrapping pitch and the thread’s mechanical characteristics. It turned out that the maximum equivalent stresses of an empty traditional tank of continuous thickness are 35 % higher than the stresses of a tank with variable thickness. At that, the equivalent stress index of a prestressed tank with variable wall thickness is 13 % higher than of a tank with constant wall thickness in all three cases of winding a plain composite thread. It should be noted that with an increase in the winding pitch, the equivalent stresses of the prestressed tank decrease by 1.5 times, in the case of winding 1:1 and 1:2. When considering the case of 1:1 and 1:3, the stresses decrease by 2 times, in the case of 1:2 and 1:3, the stresses decrease by 1.35 times. In the modal analysis of the tank with continuous and variable wall thickness without liquid, the first 60 eigenfrequencies were obtained. An analysis of the spectrum of eigenfrequencies and their corresponding eigenvibrations for two models of the tank without liquid showed that the eigenfrequencies of the traditional empty tank are 2–7 % less than the tank with prestressing. However, it was determined that a decrease in the tank wall thickness at the upper free edge from 5 mm to 4 mm does not result in changes in the number of nodes in the circumferential direction. The results obtained will allow to effectively use the prestressing in order to improve the strength and dynamic characteristics to avoid the resonance effect in the structures under study, taking into account the wrapping of a plain composite thread.

A Finite-element Method of Solution for Optimization of Frame of Tractor Operated Single Row Maize Cobs Picker

Finite element analysis (FEA) is a computational technique that divides complex structures into small elements and solves them numerically using various partial differential equations. In agriculture, engineers can use numerical simulation based on the FEA technique to study the behaviour of various input products in order to optimise the design of any machine without developing a prototype. The present study focused to design and simulates the frame of tractor operated single row maize cobs picker by employing the FEA technique. A 3D-CAD model of the frame of a tractor-operated single row maize cobs picker was created using the Solid Works software, and a static structural test was performed using the FEA technique in the ANSYS version 15.0 workbench software. A special fixture has been developed to calculate the force required to scrape the pulpy material of the leaves in the Universal Testing Machine. According to the simulation results, maximum deformation was observed as 0.051mm while maximum shear stress and Von Mises equivalent stress were found to be 0.246 MPaPa and 1. 47 MPa, respectively at 250 N scraping forces. Additionally, it was noted that the stress values fall within the material's yield strength. The FEA approach was found to be a scientific and highly effective method for designing and simulating the frame of a tractor-operated single row maize cobs picker.

БИОМЕХАНИЧЕСКОЕ МОДЕЛИРОВАНИЕ НАПРЯЖЕННОГО СОСТОЯНИЯ ЧЕРЕПА ЧЕЛОВЕКА ПРИ УДАРЕ ПРЕДМЕТОМ ЦИЛИНДРИЧЕСКОЙ ФОРМЫ

Skull fractures are quite often observed in victims of falls, traffic accidents, attacks with the use of bats and rods. The aim of the study is to assess the stress-strain state of the human head under impact on the basis of finite element modelling. The impact is applied to the frontal region of the frontal bone by the middle part and the end of a cylindrical solid (a rod). The solid is differently oriented with respect to the in relation to the Frankfurt plane. The head model includes the epidermis (skin), bone structures of the skull, bone structures of the lower jaw, eyeballs, teeth, meninges (dura, arachnoid and pia mater), cerebrum (white and gray matter), cerebellum, brain stem, muscles and ligaments. The elements of the human head model are described by the models of a linearly elastic material, a viscoelastic incompressible material, an elastic-plastic material considering fracture, and a hyper-elastic material. The eyeballs are assumed as absolutely rigid. The finite element analysis was carried out for different values of the initial velocity of a rod, corresponding to the moment of its contact with the skin of the head. It was found out that the maximum equivalent stresses and deformations of the skull bone structures occur under impact by the middle part of the rod compared to impact by its end. The impact action of the rod leads to the maximum equivalent stresses if the rod is located at an angle of 60° to the vertical. The region of the maximum stresses is located at the intersection of the sagittal and coronal sutures, and to a greater extent, significant stresses are observed along the coronal suture. The results obtained can be used by experts in the field of forensic science to evaluate various scenarios for the occurrence of traumatic brain injury and substantiate further forensic investigations.

Regional differences in bone mineral density biomechanically induce a higher risk of adjacent vertebral fracture after percutaneous vertebroplasty: a case-comparative study.

Adjacent vertebral fracture (AVF) is a frequently observed complication after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compressive fracture. Biomechanical deterioration initially induces a higher risk of AVF. Studies demonstrated that the aggravation of regional differences in the elastic modulus of different components might deteriorate the local biomechanical environment and increase the risk of structural failure. Considering the existence of intravertebral regional differences in bone mineral density (BMD) (i.e. elastic modulus), it was hypothesized in the present study that higher intravertebral BMD differences may induce a higher risk of AVF biomechanically. The radiographic and demographic data of osteoporotic vertebral compressive fracture patients treated using PVP were reviewed in the present study. The patients were divided into two groups: those with AVF and those without AVF. The Hounsfield unit (HU) values of transverse planes from the superior to the inferior bony endplate were measured, and the differences between the highest and lowest HU values of these planes were considered the regional differences of the HU value. The data from patients with and without AVF were compared, and the independent risk factors were identified through regression analysis. PVP with different grades of regional differences in the elastic modulus of the adjacent vertebral body was simulated using a previously constructed and validated lumbar finite element model, and the biomechanical indicators related to AVF were computed and recorded in surgical models. Clinical data on 103 patients were collected in this study (with an average follow-up period of 24.1 months). The radiographic review revealed that AVF patients present a significantly higher regional difference in the HU value and that the increase in the regional difference of the HU value was an independent risk factor for AVF. In addition, numerical mechanical simulations recorded a stress concentration tendency (the higher maximum equivalent stress value) in the adjacent vertebral cancellous bone, with a stepwise aggravation of the adjacent cancellous bony regional stiffness differences. The aggravation of regional BMD differences induces a higher risk of AVF after PVP surgery through a deterioration of the local biomechanical environment. The maximum differences in the HU value of the adjacent cancellous bone should, therefore, be measured routinely to better predict the risk of AVF. Patients with noticeable regional BMD differences should be considered at high risk for AVF, and greater attention must be paid to these patients to reduce the risk of AVF. Level III b.

Mechanical influence of periacetabular osteotomy on late total hip arthroplasty.

Periacetabular osteotomy (PAO) is an effective technique to treat symptomatic hip dysplasia. However, following PAO, some patients still experience persistent pain or development of hip arthritis, requiring total hip arthroplasty (THA). Issues such as whether patients with PAO are necessarily at increased risk of post-THA complications and revision of the prosthesis remain debatable. The purpose of this study was to evaluate the biomechanical influence of PAO on the acetabulum after THA by finite element analysis. Eight patients with developmental dysplasia of the hip (DDH) diagnosed in the Fourth Medical Center of the PLA General Hospital were enrolled in this research. Patient-specific hip joint models were reconstructed from computed tomography scans, and the hip prosthesises, were established via computer-aided design (CAD) modeling technology. The finite element analysis was conducted to compare the surface and internal stress through the process mapping of the model due to the THA. Compared with the THA after PAO, the position of the high-stress area of the acetabular fossa of patients without PAO decreased, and the high-stress area developed toward the lower edge of the acetabulum. Although the high-stress area of the suprapubic branch did not change significantly, the peak stress was higher (t=.00237). The analysis of the section plane showed that the high-stress area of cancellous bone had a large distribution. The acetabular size and vertical distance of rotation center (VDRC) were significantly correlated with the maximum postoperative acetabular equivalent stress (p=.011, p=.001). In the Post group, both the horizontal distance of rotation center (HDRC) and A-ASA were significantly correlated with postoperative maximal acetabular equivalent stress, with a significance of 0.014 and 0.035, respectively. The risk of postoperative prosthetic revision following THA is not increased by PAO, although the risk of postoperative suprapubic branch fracture is increased.

Evaluation of tensile properties of spherical shaped SiC inclusions inside recycled HDPE matrix using FEM based representative volume element approach

In the current study, a FEM-based representative volume element (RVE) technique is used to evaluate the elastic modulus of recycled high-density polyethylene (rHDPE) filled spherical-shaped shaped silicon carbide (SiC). In the ANSYS 2019, the material designer (MD) module is used to generate a 3D RVE of 500 × 500 × 500 μm cuboid, with randomly dispersed spherical SiC particles (i.e., 10, 15, 20, and 30% volume fractions) inside rHDPE. The Young's modulus values extracted from the RVE technique at various volume % are substantially nearer to experimental data than other micromechanical models. The tensile performance of the composite is simulated, and it was noted that the maximum equivalent stress of 4.1133 MPa for rHDPE/30% SiC composite, which is decreased to 13.8, 7.8 and 6.8% for rHDPE/10% SiC, rHDPE/15% SiC and rHDPE/20% SiC composite respectively. The results are astounding for immediate application in the relevant field of interest.

Vibration Characteristic Analysis of Hollow Fiber Membrane for Air Dehumidification Using Fluid-Structure Interaction.

Hollow fiber membrane dehumidification is an effective and economical method of air dehumidification. The hollow fiber membrane module is the critical component of the dehumidification system, which is formed by an arrangement of several hollow fiber membranes. The air stream crosses over the fiber bundles when air dehumidification is performed. The fibers vibrate with the airflow. To investigate the characteristics of the fluid-induced vibration of the hollow fiber membrane, the two-way fluid-structure interaction model under the air-induced condition was established and verified by experiments. The effect of length and air velocity on the vibration and modal of a single hollow fiber membrane was studied, as well as the flow characteristics using the numerical simulation method. The results indicated that the hollow fiber membrane was mainly vibrated by fluid impact in the direction of the airflow. When the air velocity was 1.5 m/s~6 m/s and the membrane length was 100~400 mm, the natural frequency of the membrane was negatively correlated with length and positively correlated with air velocity. Natural frequencies were more sensitive to changes in length than changes in air velocity. The maximum equivalent stress and total deformation increased with air velocity and length. The maximum equivalent stress was concentrated at both ends, and the maximum deformation occurred in the middle. The research results provided a basis for the structural design of hollow fiber membranes under flow-induced vibration conditions.

Structural Integrity of Anterior Ceramic Resin-Bonded Fixed Partial Denture: A Finite Element Analysis Study.

This study was conducted as a means to evaluate the stress distribution patterns of anterior ceramic resin-bonded fixed partial dentures derived from different materials and numerous connector designs that had various loading conditions imposed onto them through the utilization of the finite element method. A finite element model was established on the basis of the cone beam computed tomography image of a cantilevered resin-bonded fixed partial denture with a central incisor as an abutment and a lateral incisor as a pontic. Sixteen finite element models representing different conditions were simulated with lithium disilicate and zirconia. Connector height, width, and shape were set as the geometric parameters. Static loads of 100 N, 150 N, and 200 N were applied at 45 degrees to the pontic. The maximum equivalent stress values obtained for all finite element models were compared with the ultimate strengths of their materials. Higher load exhibited greater maximum equivalent stress in both materials, regardless of the connector width and shape. Loadings of 200 N and 150 N that were correspondingly simulated on lithium disilicate prostheses of all shapes and dimensions resulted in connector fractures. On the contrary, loadings of 200 N, 150 N, and 100 N with rectangular-shaped connectors correspondingly simulated on zirconia were able to withstand the loads. However, two of the trapezoidal-shaped zirconia connectors were unable to withstand the loads and resulted in fractures. It can be deduced that material type, shape, and connector dimensions concurrently influenced the integrity of the bridge.

CFD Simulation of Centrifugal Pump with Different Impeller Blade Trailing Edges

The centrifugal pump is one of the most widely used types of power machinery in the field of ship and ocean engineering, and the shape of the impeller blade trailing edge has an important influence on their performance. To reveal the mechanism of the effect of different trailing edges on external performance, the internal flow of 16 types of impeller blade trailing edges of a centrifugal pump, consisting of Bezier trailing edges, rounding on the pressure side, cutting on the suction side, and the original trailing edge is studied by numerical simulation. The reverse flow, shaft power, and energy loss distribution in the impeller and diffuser along the streamwise direction are analyzed by calculating them on each micro control body sliced from the fluid domain. The entropy production theory and Ω-vortex identification method are used to display the magnitude and location of energy loss and the vortex structure. Finally, a static structural analysis of the impeller with different trailing edges is performed. The results show that different impeller trailing edges can clearly affect the efficiency of the pump, i.e., the thinner the trailing edge, the higher the efficiency, with the thickest model reducing efficiency by 5.71% and the thinnest model increasing efficiency by 0.59% compared to the original one. Changing the shape of the impeller trailing edge has a great influence on the reverse flow, shaft power, and energy loss near the impeller trailing edge and diffuser inlet but has little influence on the leading part of the impeller. The distribution of local entropy production rate, energy loss, and reverse flow along the streamwise direction shows similar rules, with a local maximum near the leading edge of the impeller due to the impact effect, and a global maximum near the impeller trailing edge resulting from strong flow separation and high vortex strength due to the jet-wake flow. Thinning the impeller trailing edge and smoothing its connection with the blade can reduce the vortex strength and entropy production near the impeller trailing edge and diffuser inlet, improve the flow pattern, and reduce energy loss, thus improving the pump efficiency. In all models, the maximum equivalent stress is less than 6.5 MPa and the maximum total deformation is less than 0.065mm. The results are helpful for a deeper understanding of the complex flow mechanism of the centrifugal pump with different blade trailing edges.

Study on the Mechanical Properties and the Way of Breaking the Shell of Fresh Camellia oleifera Fruit

In this study, based on the physical and mechanical parameters of Camellia oleifera, the mechanical model of Camellia oleifera was rebuilt and analysed to reveal the damage mechanism of fruit shell breakage. The results revealed that under the same conditions (e.g., axial loading form), the stress of the fruit uniformly diffused from the extrusion point to the periphery and depth, and the maximum equivalent stress was 9.4104 Mpa. While under radial loading, the stress of the fruit extended axially along the dorsal line of the tea seed, and the maximum equivalent stress was 6.9467 Mpa. The maximum stress under the two loading modes occurred at the joint between the middle column of the shell and the calyx. The increased loading displacement decreased the stress on the fruit, making it easier to break the shell of Camellia oleifera by radial extrusion. The results can serve as a reference for the development of different equipment to break the shell of the Camellia oleifera fruit.

Finite element simulation of residual stress distribution during selective laser melting of Mg-Y-Sm-Zn-Zr alloy

Selective laser melting (SLM) has been confirmed as a promising additive manufacturing technology for the formation of lightweight structural parts of magnesium alloy. However, it is noteworthy that residual stress is easily generated during the SLM process of magnesium alloy, and it will induce cracks to reduce the compactness of formed parts. In this study, a three-dimensional (3D) nonlinear transient thermodynamic coupled finite element model (FEM) was built to analyze the effects of the scanning strategy on the thermal stress evolution and residual stress distribution during the SLM process of Mg-Y-Sm-Zn-Zr alloy. Moreover, six groups of simulation tests were performed based on three different scanning strategies (i.e., successive scanning, island scanning, and orthogonal scanning). The stress values of equal scale specimens produced with the same process parameters were examined to verify the simulation results. The equivalent residual stress was the largest under the use of the successive scanning strategy, as indicated by the results. Using the island scanning, the stress distribution in the island was similar to that of successive scanning, whereas there was a high-stress island close to the interface. Besides, the average S11 and S22 residual stresses were 4.90% and 36.13% lower than that of the successive scanning, respectively. Orthogonal scanning was confirmed as the most effective scanning strategy to reduce residual stress. To be specific, the average S11 and S22 residual stresses were 25.19% and 43.12% lower than that of successive scanning when using the intralayer orthogonal scanning. The simulation and experimental verification results indicated that the maximum equivalent residual stress is the lowest (229 MPa), and the stress distribution was most uniform when orthogonal scanning was performed between 4 × 4 island.

Flow–Solid Coupling Analysis of Ice–Concrete Collision Nonlinear Problems in the Yellow River Basin

Yellow River ice is the most prominent and significant natural disaster in winter and spring in China. During the drift ice period, water transmission tunnels located in this area tend to be hit by water–drift ice coupling. Thus, it is an important issue to reduce water transmission tunnel damage by drift ice, ensure the safety of operation and maintenance, and prevent engineering failure. In this paper, a numerical simulation of the collision process between ice and the tunnel is carried out by using the fluid structure coupling method and ANSYS/LS-DYNA finite element software. In addition, a model test with a geometric scale of 1:10 is carried out to verify the numerical simulation results, and the mechanical properties and damage mechanism of drift ice impacting the tunnel concrete lining in water medium are studied. The results show the following: the experimental values of maximum equivalent stress and X-directional displacement of the flow ice on the water transfer tunnel have the same trend as the simulated values, both of which show an increasing trend with an increase in flow ice velocity. It is shown that the ice material model parameters, ALE algorithm, and grid size used in this paper are able to simulate the impact of drift ice on the water transfer tunnel more accurately. With an increase in drift ice collision angle and drift ice size, the fitted curves of equivalent stress and peak displacement in X-direction all show relationships of exponential function. The peak value of displacement in the X-direction and maximum equivalent stress decrease with an increase in the curvature of the tunnel structure. It is also shown that the influence of change in drift ice size on the tunnel lining is greater than that of a change in tunnel section form. It is found that a high-pressure field will be formed due to extrusion of flowing ice, which should be fully considered in the numerical simulation. The research method and results can provide technical reference and theoretical support for prevention and control of ice jam disasters in the Yellow River Basin.