Issue 2, 39, 2023

• An analytical solution to soil consolidation around a pile considering earthquake effect

  Y. Zhang, J. Zhang, X. Xu

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 19

  
  

  Abstract

  In this paper, an analytical solution is developed to investigate soil consolidation around a pile under earthquake loading. The solution is validated using finite element method. The influence of various parameters on excess pore water pressure is analyzed. The results show that excess pore water pressure increases with depth and is positively correlated with n and Neq/N1, while negatively correlated with η, χ, kv, and td. The values of η, χ, kv, Neq/N1, and td affect excess pore water pressure during and after the earthquake, while the value of n only affects excess pore water pressure after the earthquake. The growth rate of excess pore water pressure during the earthquake is positively correlated with n, η, kv, and Neq/N1, and negatively correlated with χ and td. The dissipation rate of excess pore water pressure during the earthquake is positively correlated with η, χ, kv, Neq/N1, and td, and negatively correlated with n. Additionally, a formula for calculating the reconsolidation settlement of pile-soil foundation after an earthquake is proposed, and the effects of pile and soil parameters on pile-soil foundation reconsolidation settlement are analyzed. The results indicate that reconsolidation settlement can be divided into two stages: rapid settlement stage and slow settlement stage. The total settlement of the foundation is positively correlated with n, η, and Neq/N1, while negatively correlated with χ, kv, and td.

  Abstract
  In this paper, an analytical solution is developed to investigate soil consolidation around a pile under earthquake loading. The solution is validated using finite element [...]

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• Development of a computer program for dimensional synthesis of a four-bar mechanism that generates a prescribed trajectory

  C. Hernandez, J. Rodriguez

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 18

  
  

  Abstract

  '' This work aims to develop a computational tool for synthesizing a four-bar linkage mechanism that can generate a prescribed path for a point coupler link to follow. The dimensional synthesis of the mechanism involves determining the lengths of each of its links. In this case, two possible configurations are evaluated: crank-rocker and/or double crank. The prescribed path consists of an arbitrary number of points contained in a plane, along with the corresponding rotation degrees of the driver element.'' Dimensioning the mechanism involves many variables, and it is possible to obtain various configurations that generate paths that are approximately the desired path. Therefore, the synthesis problem arises as an optimization problem in which the objective function seeks to minimize the Euclidean norm between the prescribed points and the points earned. To solve the optimization problem, a user-friendly computer program called SIDIGETRA was developed using the genetic algorithms numerical technique. Design constraints were imposed to obtain an open configuration of the mechanism and to avoid branching defects, order, and Grashof. The program's proper functioning was validated by comparing the results obtained in case studies published in a research article in which the genetic algorithms technique was also applied. The percentage relative errors between the coordinates of the obtained points and prescribed points were calculated and found to be satisfactory. Additionally, the results generated by SIDIGETRA were validated with a visual comparison between the prescribed trajectory and the one obtained by simulating the position analysis of the synthesized mechanism using a commercial software tool designed for this purpose.

  Abstract
  '' This work aims to develop a computational tool for synthesizing a four-bar linkage mechanism that can generate a prescribed path for a point coupler link to follow. [...]

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• An improved FEM-DEM coupling simulation for granular-media-based thin-wall elbow tube push-bending process

  H. Liu, G. Ma, Z. Geng

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 17

  
  

  Abstract

  The granular-media-based push-bending process has been developed to manufacture thin-wall elbow tube with t/D≤0.01 (the ratio of wall thickness to outer diameter) and R/D≤1.5 (the ratio of bending radius to outer diameter). In the process, a tubular blank is filled with granular media and then pushed into a die to form an elbow shape. To investigate the process, a FEM-DEM coupling model has been developed, in which FEM is used to simulate bending deformation of tubular blank, and DEM is used to calculate contact forces between spherical particles in granular media. In this work, an improved numerical formulation is proposed in order to reach mechanical equilibrium quickly and accelerate the convergence of DEM simulation, when the new contacts are no longer created and the old contacts are no longer deleted in granular media. Using the proposed numerical formulation, the improved FEM-DEM coupling simulation for granular-media-based thin-wall elbow tube push-bending process is less time-consuming than before under the same simulation condition. 

  Abstract
  The granular-media-based push-bending process has been developed to manufacture thin-wall elbow tube with t/D≤0.01 (the ratio of wall thickness to outer diameter) and R/D≤1.5 [...]

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• Design and performance research of single rubber cylinder for high pressure gas injection packer

  L. Zhang, S. Wang, W. Lv, G. Yue, Y. Ge, Z. Zhao, X. Zhou

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 16

  
  

  Abstract

  In order to solve the problem of "gas explosion" at the end of common rubber cylinder in the process of high temperature, high pressure and gas drive operation, the rubber cylinder with new structure suitable for 51/2 in casing pipe is developed. The "M" type single rubber cylinder structure is adopted in the new structure rubber cylinder, and the "gas explosion" problem of the end gas in the low-pressure side is solved by setting the double-layer staggered slotted steel cover to prevent outburst. The finite element method is used to simulate the setting of the rubber cylinder, and the structural parameters of the new rubber cylinder are obtained by single factor analysis and orthogonal optimization, simulation test and seal test were carried out to verify the sealing performance of the rubber cylinder. According to the actual working condition, the simulation test results and seal test results show that the sealing capacity of the packer reaches 50 MPa under the temperature resistance of 120℃, and the end steel cover is fully opened to wrap the rubber cylinder, which meets the operation requirements of high temperature and high pressure gas injection packer.

  Abstract
  In order to solve the problem of "gas explosion" at the end of common rubber cylinder in the process of high temperature, high pressure and gas drive operation, [...]

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• Behaviour of self excited synchronous generator loaded by different sizing induction motors

  N. Mounir, F. Said, M. Enany

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 15

  
  

  Abstract

  The modeling of both the synchronous generator and induction motor which is represented by the rotor reference frame was studied where the modeling was established using MATLAB /SIMULINK software package for an isolated synchronous generator direct-on-line with different sized induction motors; 20, 50, and 100 Hp, at manually adjusted excitation voltage values which were maintained constant at 3.35, 4.55, and 6.21 V, respectively. The purpose of this work is to study the impact of a sudden increase in the load torque; from 0 to 150 % with an increase of 25 %, of full load torque was studied at a constant motor speed of 188.49 rad sec-1. On the other hand, the impact of a sudden decrease in the rotor speed by about 20 % from its rated value; from 188.49 to 150.79 rad sec-1 was also studied at full load torque of the same different-sized induction motors. These values were manually recorded and response variables of the generator including terminal voltage, current, output power, electromagnetic torque, and load angle were determined and represented as a function of time. The results illustrated the Changes in the terminal voltage, the current, the output power, the electromagnetic torque, and the load angle as parameters of a synchronous generator for different-sized induction motors.

  Abstract
  The modeling of both the synchronous generator and induction motor which is represented by the rotor reference frame was studied where the modeling was established using MATLAB [...]

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• A deep learning-based prognostic framework for aeroengine exhaust gas temperature margin

  W. Fu, X. Tan, L. Ao, Y. Fu, P. Guo

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 14

  
  

  Abstract

  The value of the gas-path parameter, exhaust gas temperature margin (EGTM), is the critical index for predicting aeroengine performance degradation. Accurate predictions help to improve engine maintenance, replacement schedules, and flight safety. The outside air temperature (OAT), altitude of the airport, the number of flight cycles, and water washing information were chosen as the sample input variables for the data-driven prognostic model for predicting the take-off EGTM of the on-wing engine. An attention-based deep learning framework was proposed for the aeroengine performance prediction model. Specifically, the multiscale convolutional neural network (CNN) structure is designed to initially learn sequential features from raw input data. Subsequently, the long short-term memory (LSTM) structure is employed to further extract the features processed by the multiscale CNN structure. Furthermore, the proposed attention mechanism is adopted to learn the influence of features and time steps, assigning different weights according to their importance. The actual operation data of the aeroengine are used to conduct experiments, where the experimental results verify the effectiveness of our proposed method in EGTM prediction.

  Abstract
  The value of the gas-path parameter, exhaust gas temperature margin (EGTM), is the critical index for predicting aeroengine performance degradation. Accurate predictions help [...]

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• Simulación de fenómenos de daño para metamateriales

  R. Montero-Mayoral, V. González-Albuixech, M. Sanz-Gómez, V. Yanes

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 13

  
  

  Abstract

  Metamaterials are generated from an interrelated set of cells and can present a macroscopic behaviour that differs from the one that characterizes its basic constituents. Modelling the influence that the damage and fracture of the elemental constituents have in the macroscopic properties of the metamaterial is relevant for its mechanical analysis. Altering the resistant behaviour of the elements (changing their longitudinal elastic modulus), it is possible to approximate the effect of the damage in the complete structure.  It is considered as valid the substitution of the damage and plastic deformation phenomena by intermediate states contained in the linear elastic deformation regime. Each state is characterized by the elastic module of the element, whose geometry remains unmodified. In an iterative process, when the induced stress in the elements is greater than the one stablished as the limit, they progress through the different states, diminishing their elastic modulus until they are considered as fractured and are eliminated from the structure. Mass effects are ignored, and a stress-free structure is implemented to calculate each iteration. A simple algorithm is presented to simulate the effect of damage in metamaterial structures, applicable to any finite element software.

  Abstract
  Metamaterials are generated from an interrelated set of cells and can present a macroscopic behaviour that differs from the one that characterizes its basic constituents. [...]

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• Combination of 3D solid finite elements with rotation-free beam elements for non-linear analysis of fiber reinforced polymer rebars

  F. Zarate, T. Villette, X. Martinez, F. Rastellini Canela, D. Cendón, C. Andrade, E. Oñate

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 12

  
  

  Abstract

  We present a combination of three dimensional (3D) solid elements and rotation-free beam elements for non-linear analysis of fiber-reinforced polymer (FRP) of rebars. The matrix material is modelled by 3D solid elements while the fibers are modelled with rotation-free beam elements. The absence of rotation variables in the beam elements allows the straightforward coupling of 3D solid and beam elements using a formulation with displacement nodal degrees of freedom only. Both solid and beam elements are formulated in an updated Lagrangian description. The behavior of the matrix and the fiber material are modelled with an elastic-damage model. The efficiency and accuracy of the combined 3D-beam element formulation are verified in examples of application to the analysis of FRP rebars up to fracture in axial, bending and shear tests for which experimental results are available.

  Abstract
  We present a combination of three dimensional (3D) solid elements and rotation-free beam elements for non-linear analysis of fiber-reinforced polymer (FRP) of rebars. The [...]

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• Bearing life prediction based on critical interface method under multiaxial random loading

  J. Ling, L. Haoyu, Q. Wang, L. Cheng

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 11

  
  

  Abstract

  The bearing was a key component of the mining machine tire unloader machine and was subjected to random multiaxial stress during operation. Therefore, the life prediction of bearing was of safety guidance. In this paper, a bearing life prediction method based on the critical plane method under multiaxial random loading was proposed. Firstly, a virtual prototype model was built based on the actual working conditions of the tire unloader machine to obtain the time load history of the bearing. Transient dynamic analysis of the bearing was carried out to obtain the triaxial stress-strain time histories at the hazardous locations of the bearing. A new coordinate system was established using the hazard node as the coordinate origin, and the location of the critical plane was searched for based on the critical plane multiaxial fatigue theory, combined with the maximum shear strain amplitude on the critical plane for multi-axial rain flow cycle counting to obtain the damage amount in each direction. At the same time, the life calculated from the maximum damage amount was used as the final life, resulting in a cycle count of the bearing of 268,303 cycles and a duration of 1490.58h. The results of this study could be used as a guide to predict the service life of the bearing in large machinery subjected to multiaxial random stress conditions.

  Abstract
  The bearing was a key component of the mining machine tire unloader machine and was subjected to random multiaxial stress during operation. Therefore, the life prediction [...]

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• Study on dynamic response characteristics of radial steel gate under rare earthquake considering fluid structure coupling effect

  S. Shi, Y. Han, K. Hu, Y. Zhou, T. Hu, Y. Lou, J. Wang, T. Hou

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 10

  
  

  Abstract

  The water resources in southwest China is abundant and the seismicity is strong, so it is necessary to study the dynamic response and safety of hydraulic structures under rare earthquake. Taking a typical radial steel gate as an example, a three-dimensional numerical model considering the interaction between water and gate during the earthquake is established. The accuracy and applicability of the model are verified by comparing with the measured results of the dynamic response of Zipingpu dam during the Wenchuan earthquake. Thereafter, the dynamic displacement and stress, and resonance frequency of the radial gate under the rare earthquake of two wave types are analyzed. The water-structure coupling effect has a great influence on the seismic dynamic response of the radial steel gate. The calculated result of the dynamic response of the gate considering the fluid-structure coupling effect is significantly larger than that of the specification, and the maximum ratio of the two is more than 2.27 times. Under the action of EI wave, the peak value of dynamic stress response is at the bottom of the panel, and the maximum value of resonance frequency (about49.13 Hz) is located in the middle and lower part of the panel. Under the action of far-field wave, the peak area of dynamic displacement response of the gate is basically the same as that under the action of EI wave, while the maximum value of some measuring points is only half of the maximum value under the action of EI wave. However, the resonance frequency is significantly greater than that of EI wave, the maximum value reaches 65.24 Hz, which appears at the top of the gate. The dynamic response of the gate structure caused by two different wave types of earthquakes is not completely consistent. The comprehensive consideration of different wave types is of significance for the structural design and safety evaluation of the radial steel gate in the earthquake-prone areas.

  Abstract
  The water resources in southwest China is abundant and the seismicity is strong, so it is necessary to study the dynamic response and safety of hydraulic structures under [...]

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• A new calculation method of bearing reliability of tyre unloader based on heterogeneous dimensional interference model

  J. Ling, R. Zhang, J. Shao, H. Zhang

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 9

  
  

  Abstract

  Bearing is an important rotating support part of tyre unloader, and its fatigue reliability is an important part of the whole system reliability. Because of the huge alternating stress, the support bearing is required to have high fatigue life and reliability. In this paper, combined with stress-strength interference model and statistical theory, the life distribution of bearing steel material is predicted by using group test data; Based on the multi-rigid body dynamics and finite element numerical simulation platform, the reliability of the bearing of tyre unloader under different operating years was predicted by using the different dimensional interference model. The results show that the maximum resultant force of the bearing at the bottom rocker arm of the tyre unloader can reach 150kN, and the maximum transverse and longitudinal forces can reach 108kN and 78kN. When bearing the weight of the whole tyre and turning, the inertia force is the largest, the maximum stress value is 1316.2MPa, which occurs in the bearing inner ring and ball contact part. After the statistics, the stress amplitude distribution of the bearing conforms to Weibull distribution, and the life of the bearing follows lognormal distribution. After 105 tyre unloading, the fatigue reliability of the bearing is lower than 0.82, which is consistent with the actual working condition. Therefore, this model can be used to calculate the fatigue reliability of bearings conveniently and quickly, and provide certain theoretical support for the safety and fatigue reliability prediction of bearings.

  Abstract
  Bearing is an important rotating support part of tyre unloader, and its fatigue reliability is an important part of the whole system reliability. Because of the huge alternating [...]

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• Structure design and performance analysis of downhole hydraulic decoder

  H. Fang, X. Zhou, Z. Liu, Y. Peng, Y. Wu, J. Li

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 8

  
  

  Abstract

  In order to reduce the number of hydraulic decoders and hydraulic control pipelines in hydraulically controlled intelligent wells, reduce production costs and improve oil recovery efficiency, the structural design of ICV control of two hydraulic control pipelines and a single hydraulic decoder for four production layers in the well was completed. By simulating the response law of downhole hydraulic signals and the stress analysis of each structure, the motion equation of the layer selection structure of the hydraulic decoder was established with 4 MPa as the unlocking pressure, and ADAMS was used to complete the dynamic simulation analysis. The variation results of displacement, angle, velocity and acceleration in the process of motion were obtained. Finally, the prototype of the hydraulic decoder was processed by stereo photo curing 3D printing equipment. Two hydraulic pumps were used to press alternately, and the selection of four layers of the hydraulic decoder was realized through two hydraulic control pipelines. The self-locking structure could realize the established function, and there was no interference and stuck between the components, which verifies the effectiveness of the design.

  Abstract
  In order to reduce the number of hydraulic decoders and hydraulic control pipelines in hydraulically controlled intelligent wells, reduce production costs and improve oil [...]

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Issue 1, 39, 2023

• Spectral and wavelet analysis in the wake of an airfoil with Gurney flap

  P. Giacopinelli, A. Scarabino, F. Bacchi, J. Delnero

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 7

  
  

  Abstract

  In this work we identify the coherent vortices in the leeward wake of an HQ 17 airfoil with a Gurney flap. This high-lift device consists of a small plate perpendicular to the airfoil, at or near the trailing edge, with a height H of the order from 1% to 4% of the chord. The overall effect is to produce a significant increase in lift, together with a relatively minor increase in airfoil drag. Its geometry generates vortex shedding of spatial scale H, which modulates the wake and thus influence the global configuration of the flow. A numerical study was performed with the commercial software ANSYS Fluent. Simultaneously, experiments were carried out in the wind tunnel of the Aeronautical Departmental Area from the Engineering School of the National University of La Plata. With a Dantec StreamLine hot-wire anemometer, records of the instantaneous horizontal and vertical velocity components in the airfoil wake were obtained. Both the experimental data and those obtained by numerical simulation were analyzed with the continuous wavelet transform technique, in order to identify and characterize the coherent vortices in the wake. Results show the shed vortices structure and the organization degree of this periodic shedding.

  Abstract
  In this work we identify the coherent vortices in the leeward wake of an HQ 17 airfoil with a Gurney flap. This high-lift device consists of a small plate perpendicular to [...]

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• Characterisation of mechanical behaviour of fibre reinforced thermoplastic composites subjected to off-axis compressive loading

  Y. Ma, Y. Li, L. Liu

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 5

  
  

  Abstract

  This paper presents an experimental and numerical investigation on the mechanisms of damage onset and evolution in unidirectional carbon fibre reinforced thermoplastic (CFRTP) composites subjected to off-axis compressive loadings. A test fixture was designed to prevent buckling, splitting and end collapsing of specimens during test. A series of compression tests were conducted with specimens of various off-axis angles. Different failure mechanisms and nonlinear stress-strain responses were observed and studied. The fracture angles of the tested specimens were evaluated and analysed according to Puck’s theory. The off-axis compression failure envelope based on LaRC05 and Hashin criteria was presented using finite element analysis and compared to experimental results. It is shown that the LaRC05 criterion can provide accurate predictions for matrix cracking failure mode of unidirectional thermoplastic composites controlled by compression-shear combined stresses.

  Abstract
  This paper presents an experimental and numerical investigation on the mechanisms of damage onset and evolution in unidirectional carbon fibre reinforced thermoplastic (CFRTP) [...]

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• Parallel computing for reducing time in security constrained optimal power flow analysis

  D. Alvarez, D. Rodriguez, S. Rivera

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 4

  
  

  Abstract

  This paper presents a novel approach for solving the security-constrained optimal power flow (SCOPF) optimization problem using parallel Computing. In this approach, switched shunt banks, generation power ramp, and demand response are considered in the SCOPF by maximizing the market surplus during regular operation and for a set of contingencies of branches and generators. The optimization problem is solved using the Nonlinear Interior Point Method. The contingency assessment is paralleled in multiple CPU cores to decrease the computation time. Additionally, the test systems used in ARPA-GO competition were used and compared with the ARPA benchmark results to assess the proposed algorithm. The numerical results show this method is suitable for fast SCOPF using paralleling Computing.

  Abstract
  This paper presents a novel approach for solving the security-constrained optimal power flow (SCOPF) optimization problem using parallel Computing. In this approach, switched [...]

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• A BP neural network-based micro particle parameters calibration and an energy criterion for the application of strength reduction method in MatDEM to evaluate 3D slope stability

  W. Jiang, Y. Tan, J. Yan, Y. Ouyang, Z. Fu, Q. Feng

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 3

  
  

  Abstract

  To enhance the applicability of discrete element method in 3D slope stability analysis, a BP neural network-based micro parameter calibration method and an energy criterion are proposed by taking MatDEM as an example. Firstly, the relationship between the micro particle parameters and the shear strengths of particle aggregate are represented by using the BP neural network. And then the micro particle parameters are obtained for the given shear strengths by using a correction calibration. Next, the energy conversions are investigated for the stable and instable slope models in MatDEM. From a view of practical application, the abrupt in variation tendency and magnitude of the kinetic energy is selected for indicating the emergence of the limit equilibrium state of a slope. Finally, the effectiveness of the proposed improvements is testified by taking Baijiabao landslide as an example. Results verify that the calibration method established in this study is applicable to provide the micro particle parameters when the shear strength is constantly reduced, and the factor of safety determined by the kinetic energy criterion reflects the landslide stability at the global level.

  Abstract
  To enhance the applicability of discrete element method in 3D slope stability analysis, a BP neural network-based micro parameter calibration method and an energy criterion [...]

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• Passive periodic motion of an asymmetric spring loaded inverted pendulum hopping robot

  Y. Ni, X. Meng

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 2

  
  

  Abstract

  For improving the energy efficiency of hopping robot, an asymmetric spring loaded inverted pendulum hopping model with leg mass is considered. The period orbit problem of one-legged hopping robot is investigated. Firstly, the hybrid dynamic model is constructed. Then the passive hopping gaits are found using quasi-newton optimization method. Secondly, a PD controller is implemented to track the desired pitch trajectory of the body. Through applying control during stance phase, period orbits of the robot with offset body mass is obtained. Finally, the effect of the location of the leg mass and the body mass on hopping performances is investigated.

  Abstract
  For improving the energy efficiency of hopping robot, an asymmetric spring loaded inverted pendulum hopping model with leg mass is considered. The period orbit problem of [...]

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• Construction monitoring and finite element simulation of assembly support for large cantilever cover beam

  C. Qu, H. Fang, Q. Feng

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (1), 1

  
  

  Abstract

  The study on the assembly support for the large cantilevered cover beam was carried out by conducting real-time monitoring on the assembly frames’ strain and displacement development processes in the actual project. Modeling of the support and numerical simulation for actual working conditions were presented. The monitoring data and analysis results show that the overall stress ratio of the support was less than 30%. And as the concrete structure being supported hardened, the support frame was unloaded. When the stress ratio was then reduced to less than 10%, it was the most appropriate time to remove the bracing frame. The maximum strain from the simulation did not exceed 66.26% of the theoretical maximum strain of the rod. The actual construction conditions and the spatial form of the support affected the force situation, resulting in the deviation from the theoretical maximum strain at certain phases. The analysis results and trends reflect the low utilisation rate of such framing rods. The results of the study can be used as a reference for the topology optimisation of assembled support frames for large cantilevered cover beams.

  Abstract
  The study on the assembly support for the large cantilevered cover beam was carried out by conducting real-time monitoring on the assembly [...]

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• Optimal Allocation of UPFC for Congestion Management using ANTLION Algorithm

  K. Duraisamy, P. S, M. Kumar

  Rev. int. métodos numér. cálc. diseño ing. (Online first).

  
  

  Abstract

  To obtain an optimum power market the deregulation process is implemented for the entire electrical market and further classified as transmission and distribution units. Each firm focuses on delivering its best output which leads to congestion issues on transmission lines as there is in-adequate transmission capability to satisfy the load demand, and transmission congestion occurs. Transmission cable congestion results from a lack of coordination between the utilities that handle generating, transmission, and distribution leading to a generator failure, an abrupt increase in load demand, or the miscarriage of equipment, all of which can be fixed by FACTS devices. In this work, transmission line congestion is reduced using FACTS devices like UPFC and IPFC. The primary goal is to determine where FACTS devices should be placed. The main goal is to use the ANTLION optimization algorithm to locate the optimal position and size for FACTS devices. In an IEEE-14 bus system, UPFC and IPFC are individually connected and parameters are analyzed and formulated for better transmission among energy sectors.

  Abstract
  To obtain an optimum power market the deregulation process is implemented for the entire electrical market and further classified as transmission and distribution units. Each [...]

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• Integración reducida estabilizada y análisis lineales secuenciales en la aproximación del comportamiento no-lineal de estructuras

  H. Amezcua Rivera, A. Milián

  Rev. int. métodos numér. cálc. diseño ing. (Online first).

  
  

  Abstract

  In this paper, a computationally efficient strategy for the approximation of the non-linear behaviour of structures through the finite element method is proposed. This proposal is based on the execution of a set of linear analyses in which the strength of the elements where the damage occurs is sequentially degraded and, in addition, complemented with a stabilized reduced numerical integration scheme for solid finite elements. Thus, the stiffness matrix only contains information of one integration point and, consequently, the stresses are computed only at that point. Also, due to the stabilization, it is possible to use reduced integration not only in the elements where the damage is assumed to occur, but in all the elements, guaranteeing a greater reduction in the computational cost. In this paper, the strategy of sequentially linear analysis with stabilized reduced integration is applied to several validation as well as application examples in which the quality of the approximation and the computational efficiency achieved are discussed. Finally, some future developments for the strategy are proposed.

  Abstract
  In this paper, a computationally efficient strategy for the approximation of the non-linear behaviour of structures through the finite element method is proposed. This proposal [...]

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• Influência das superfícies sub-críticas no comprimento de reforços em estruturas de solos reforçados com geotêxteis ou geogrelhas

  R. Puppi, J. Caron

  Rev. int. métodos numér. cálc. diseño ing. (Online first).

  
  

  Abstract

  '''– Design of steep slopes and retaining walls, reinforced with geotextile or geogrids, requires internal stability checks usually referred to a critical failure surface, which determines the amount of reinforcement required. In determining the length of the reinforcement layers the position of the critical surface and also of the sub-critical surfaces must be considered. In relation to these, are verified the anchorage lengths required to ensure the pullout resistance of the reinforcements. This paper presents a study based on limit equilibrium analysis, with bi-linear failure surface, to determine the amount and length of the reinforcement layers required. The model allows replacing Jewell charts by algebraic equations and iterative calculation processes. The results obtained for the minimum length of reinforcements agree with good accuracy for effective friction angles greater than or equal to 30° and indicate that shorter lengths can be used for materials with lower effective friction angle. Expressions for the calculation of the anchorage length are also presented for the three possible cases: anchorage in a section under the projection, part under the projection and beyond the horizontal projection of the slope face. '''Palavras Chave –''' talude, solo reforçado, geotêxtil, geogrelha, superfície sub-crítica, comprimento de reforço. '''Key words''' – slope, reinforced soil, geotextil, sub-critical surface, reinforcement length. *Professor Associado, D.Sc. UTFPR - Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brasil. E-mail: [mailto:rfkpuppi@utfpr.edu.br rfkpuppi@utfpr.edu.br] / [mailto:rfkpuppi@gmail.com rfkpuppi@gmail.com] **Professor EBTT, M.Sc. UTFPR - Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brasil. E-mail: [mailto:caron@utfpr.edu.br caron@utfpr.edu.br]

  Abstract
  '''– Design of steep slopes and retaining walls, reinforced with geotextile or geogrids, requires internal stability checks usually referred to a critical [...]

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