Mechanical APDL Research Articles

Numerical simulation, constructal design, and systematic search applied to the geometrical evaluation of hat-stiffened plates under bending

Steel plates have wide structural applications in various engineering sectors due to their combination of lightness, efficiency, and high load-bearing capacity. When stiffeners are added to these structures, the deflections can be significantly minimized. In this study, hat-stiffened plates having box-girder stiffeners with a trapezoidal shape, positioned longitudinally along the plate, are considered to evaluate their influence on the maximum and central deflection of the structure. The analyses in this work are carried out using ANSYS Mechanical APDL software, employing a validated and verified computational model developed with the SHELL281 finite element. Starting from a reference plate without stiffeners, the Constructal Design method was applied, allowing to propose different geometric configurations for plates with longitudinal hat-stiffeners, keeping the total steel volume constant. All these cases were simulated numerically and their results were compared through a Systematic Search technique. Among these 100 different cases investigated, the geometric configuration with 1 hat-stiffener of 250 mm in height and 9.53 mm in thickness achieved the best performance, resulting in a reduction of approximately 86% in maximum and central deflections compared to the reference plate. This highlights its effectiveness in minimizing out-of-plane displacements.

Determination of stresses in welded connections of railway bridges with the finite element method and global-local approach

Steel bridges are used due to their large spans with reduced self-weight, and therefore, are widely used for expanding the Brazilian railway network. However, due to the cyclic loading acting on the structure, and their limited damping capacity, the dynamic effects must be evaluated. In addition, due to the cyclic loading, the effects of fatigue must be considered. In bridges, fatigue failures account for most of the damage and collapse of structures. Thus, techniques are proposed for assessing their service life, considering fatigue failure effects. Fatigue life assessment can be performed considering the history of stresses acting on the structure, and obtaining stress history data using the finite element method yields more accurate results compared to normative methods, but it requires an extremely refined mesh to obtain adequate stress values. Therefore, this study presents a strategy for obtaining stress histories with the passage of a vehicle on a railway bridge using the commercial software Ansys Mechanical APDL v. 2020R1 and Python routines to assess the fatigue life of connections. A global-local methodology is proposed, in which a model of a bridge span using shell and beam elements is developed and subjected to the passage of a vehicle. Its displacement results are then transferred to a local connection model developed with solid elements, to determine stresses for future use in assessment of fatigue life.

Design optimization via genetic algorithms of acessible Ferris Wheels

In Brazil, systematic studies related to the design of amusement park equipment are still incipient. Essential normative references for these projects, such as NBR 15926-2 and ISO 17842-1 which deals with design and installation safety requirements, are often not effectively applied, increasing the risk of structural failures and neglecting stability and operational safety evaluation. Consequently, most of these equipment are imported, lacking national designs. The aim of this paper is to perform a preliminary analysis of the structural design of an accessible flexible Ferris wheel, evaluating safety coefficients through a parametric study of its geometry, including actions related to its operation, loading, and wind action. The structure modeling is conducted via Finite Element Method (FEM) using Ansys Mechanical APDL software using beam and mass elements. A routine implemented through MATLAB software communicates the input parameters and the modeled structure via FEM, allowing an easy alteration of the geometric variables, as well as the rectangular or square steel tube sections standardized by NBR-6591. Finally, a multi-objective optimization is implemented via Genetic Algorithms (GAs) with a fitness function aiming to maximize the safety coefficient and minimizing the mass. Optimal combinations are investigated and compared, proving the efficiency of this design methodology.

Разработка математической модели деформационного поведения изоляционной перемычки в процессе гидрозакладки горной выработки

Implementing measures to eliminate the negative consequences of soil subsidence during mine workings is an urgent problem. One of the methods to close mine workings not in operation is the technology of hydraulic filling; new types of insulating jumpers are studied in order to improve the technology. To select optimum dimensions of the structural elements, a comprehensive study of the impact of geometry and materials structure on its operability is required. The ANSYS Mechanical APDL software package provides a mathematical model of the deformation behavior of the insulating jumper with step-by-step backfilling of the worked space with a backfill mixture. The model is fully parametrized in accordance with the geometrical dimensions of the structure, the mechanical properties of materials, the space-filling rate, and the backfill mixture properties. This enabled the automation of the process of analysis of the impact of technological solutions and the nature of filling the worked mine space on the operability of load-bearing structural elements. Within the framework of the first approximation, the impact of the bearing frame wall thickness on the waterproof jumper stress-strain state has been evaluated; the behavior of the structure during a step-by-step filling and under instantaneous load has been compared.

Experimental studies and non-linear finite element analysis of flexural behavior of steel fibre-reinforced concrete under monotonic and repeated cyclic loading

Experimental studies were carried out on beams of size 150 mm × 150 mm × 550 mm, subjected to four-point bending under monotonic and repeated cyclic loading. Hooked-end steel fibres of aspect ratio 50 (50 mm length and 1 mm diameter), at fibre volume fractions—1.0, 1.25, 1.5 and 1.75% for concrete of grade M20 was considered for the study. The load-deflection, moment-curvature and toughness responses were arrived through the tests. Non-linear Finite Element (FE) analysis was carried out for all the tested SFRC beams which were modelled and analyzed using robust and reliable FE tool ANSYS Mechanical APDL 2022 R2. The load-deflection responses arrived through FE analysis were compared and validated with the experimental results. Further the moment-curvature response shown was found to be influenced by the random distribution of steel fibres. This aspect considerably influenced the moment-curvature response under repeated cyclic loading. The ultimate load in flexure was found to be 122%, 133%, 156% and 183% higher for fibre volume fractions of 1.0, 1.25, 1.5 and 1.75%, respectively. Also, the toughness measured was found to be higher by 1993%, 2072%, 1748% and 1833% for fibre volume fractions of 1.0, 1.25, 1.5 and 1.75%, respectively when compared to the plain concrete under monotonic loading. The non-linear FE analysis of SFRC beams were found to be reliable for analyzing the flexural behavior of SFRC members.

An ANSYS user cohesive element for the modelling of fatigue initiation and propagation of delaminations in composite structures

A deeper understanding of delamination growth under fatigue loading in composite wind turbine blades is required. A new cohesive model for delamination fatigue initiation, which uses initiation S-N curve data to calculate the number of cycles to the introduction of delaminations, is developed and tailored to a state-of-the-art model for fatigue propagation. Both models are implemented in a novel user-defined cohesive element for ANSYS Mechanical APDL. In fatigue propagation-dominated test cases, including with multiple delaminations, the crack growth rate evolution is accurately predicted. In fatigue initiation-dominated cases, a satisfactory prediction is achieved, also showcasing the ability to model fatigue propagation after initiation.

Thermal responses of a concrete slab under hydrogen fuel cell vehicle fires in a semi-open car park

This work aims to investigate the thermal behaviors of the concrete ceiling slab of a semi-open car park exposed to localized fire in hydrogen fuel cell vehicles. For this purpose, a numerical simulation of the hydrogen fuel cell vehicle fire was performed in the Fluid Dynamic Simulator and then coupled with a subsequent thermal analysis of concrete structure carried out in ANSYS Mechanical APDL. In particular, an automatic procedure was used to extract the output of the fire simulation and apply them as boundary conditions of the thermal model. The one-way coupling procedure involving fire simulation and transient thermal analysis has been validated by comparing it with concrete temperatures of a previous test study. Then, two parameters, the diameter of thermal pressure relief devices (1 mm, 2 mm, 3 mm, and 4 mm) and fire spread time between vehicles (0 min, 20 min, and 30 min), are taken into account to study the thermal properties of concrete. The analysis revealed that an increase in the nozzle diameter of the thermal pressure relief device leads to a rise in the maximum concrete surface temperature. The simulation results also showed that the maximum value of the heat release rate increases with a higher value of the nozzle diameter of the thermal pressure relief device and a shorter fire spread time between vehicles.

Numerical Modelling and Simulation for Sliding Wear Effect with Microstructural Evolution of Sputtered Titanium Carbide Thin Film on Metallic Materials

Titanium carbide materials are introduced into manufacturing industries for the reinforcement and surface protection of base materials due to their substantial ability to withstand severe environments, which include sliding wear, corrosion, and mechanical failures. A thin film of titanium carbide (TiC) is coated onto brass and copper substrates using the radio frequency magnetron sputtering (RFMS) deposition method. The coating process is carried out at constant processing parameters, which include a sputtering power of 200 W, a temperature of 80 °C, a deposition time of 180 min, and an argon (Ar) gas flow rate at 10 standard cubic centimetres per minute (SCCM). The coating, together with the base materials, is modelled and its behaviours are simulated using ANSYS Workbench R19.2 Academic, supported by Mechanical APDL solver for nonlinear finite element analysis (FEA). The deformation, equivalent stress–strain characteristics, and elastic–plastic properties of the coating are determined at applied loads of 60 N and 25 N and coefficients of friction (CoF) of 0.25 and 0.38 for the thin film deposition on brass and copper substrates. The sliding distance and the speed of the alloy steel ball used during the sliding wear operation are found to be 3 mm and 4 mm/s, respectively. The sliding wear modelling and simulation process are, however, designed for the ball-on-flat (BoF) wear technique with a dry sliding approach. Therefore, BoF wear simulations are also performed on titanium carbide–brass (TiC-Br) and titanium carbide–copper (TiC-Cu) conjugates for the evaluation of surface engineering applications such as cutting tools and in automotive, aerospace, thermomechanical, and biomedical fields. The ball used for the FEA wear simulation is made from alloy steel material (AISI 52100) with a radius of 3.175 mm.

The Geometric Configuration of Lubricant Recesses of the Polymer Sliding Layer of the Bearing

Polymers have gained a foothold in the international market and are actively utilized at a large scale in various industries. They are used as sliding layers in various types of friction units. However, there is a lack of research on their deformation behavior under different design conditions. This work is focused on studying the influence of the geometrical design of lubrication recesses in a polymer sliding layer operating under conditions of frictional contact interaction. The article investigated an element of bridge-bearing steel plate with recesses for lubrication. Two geometrical configurations of recesses are studied: the annular groove and spherical well in the engineering software package ANSYS Mechanical APDL. Polytetrafluoroethylene (PTFE) is considered an elastic-plastic sliding layer. A comparative analysis of two models with different geometrical configurations of cutouts for lubrication, with/without taking into account its volume in the recess, has been conducted. The article establishes that in the absence of lubrication in the recesses, large deformations of the polymer sliding layer occur. This effect negatively affects the structure as a whole. Changing the geometry of the recess for lubrication has the greatest effect on the intensity of plastic deformations. Its maximum level is lowered by almost ~60% when spherical notches are used for lubrication instead of grooves. The friction coefficient of the polymer has a great influence on the contact tangential stress. At the experimental coefficient of friction, it is lowered on average by ~85%. The friction coefficient of the lubricant has almost no effect on the deformation of the cell (<1%).

Influence of tension and deformation indicators on the quality of removable constructions acrylic basis

Background. The question of distribution of masticatory pressure is one of the main branches in quali­tive manufacturing of removable constructions. With the development of software, as well as with the increase in the power of computer technology has also spread to the problems of biomechanics, in particular the biomechanics of the human oral cavity. The aim of our study was to analyze the results of using the method of finite element techniques with the purpose to improve the quality of prosthetic treatment by correct modeling constructional denture elements. Materials and Methods. The study involved 45 patients aged 44–73 years (mean age 59.2±4.3) treated with complete laminar prosthetic constructions for the upper jaw and lower jaw. A powerful method was developed to solve the problems of the theory of elasticity – the finite element method. The main idea is that the body under the study is divided into a finite number of subdomains or elements on which the desired continuous function is approximated by a polynomial (consists of piecewise continuous functions). A two-dimensional quadrangular element with four nodes was chosen as the partition element. Dividing it into elements and further solving the problem was in the ANSYS Mechanical APDL package (USA). Results. Regarding the calibration of the ultimate displacements of nodal points and as a result of the distribution of masticatory pressure under the basis of a complete removable dentures on the tissues of the prosthetic area, the average values of each plane were as follows: for section PM1 – the plane with high pressure was ([675298.14±5.21] m2K). Taking the PM2 region, the values were slightly higher ([369743.3±3.9] m2K) and ([735356.34±4.52] m2K), respectively. Conclusions. Our findings suggest direct relationship between the using of mathematical calculation of material volume, volume deformation, potential data and elasticity theory as auxiliary element in the manufacture of removable dentures and, as a result, direct influence on level of quality of following constructions. Keywords: orthopedic treatment, finite element method, complete removable dentures, tension theory, deformation.

Prediction of carbon nanotubes reinforced interphase properties in fuzzy fibre reinforced polymer via inverse analysis and optimisation

This paper presents the parameter identification procedure of carbon nanotubes (CNTs) reinforced interphase in fuzzy fibre reinforced polymer (FFRP). The procedure was completed with ANSYS Workbench 19.2 software by combining Mechanical ADPL and Goal-Driven Optimisation. Firstly, a three-phase representative volume element (RVE) containing carbon fibre, CNTs reinforced interphase and epoxy resin was developed as a collection of Mechanical APDL commands. This RVE model was simulated to evaluate the elastic constants of FFRP lamina. CNTs reinforced interphase was characterised by transversely isotropic model. Interphase properties were parametrised and became input parameters in the Goal-Driven Optimisation. FFRP lamina elastic constants were set as the output parameters. Multi-objective Genetic Algorithm (MOGA) was used to identify the interphase properties, so that the output FFRP lamina elastic constants match the objective and constraints. The optimisation algorithm converged after 585 evaluations. Five potential candidate point, which met required objectives and constraints, were found. The identified interphase properties agreed well with the literature (an average percentage error of around 2%). This inverse procedure shows the potential to identify the interphase properties in nano-engineered composites, which are extremely difficult to measure experimentally.

Fatigue Crack Growth Studies under Mixed-Mode Loading in AISI 316 Stainless Steel

The objective of this study is to examine the behavior of fatigue crack growth (FCG) in the mixed mode (I/II) of the AISI 316 austenitic stainless steel alloy, considering mode mixity angles of 30°, 45°, and 60°. This particular alloy is widely used in the marine industry and various structural components because of its exceptional properties, such as high corrosion resistance, good formability, weldability, and high-temperature strength. By investigating the crack growth behavior, the study seeks to provide insights into the material’s durability and potential for long-term use in demanding applications. To analyze fatigue crack growth behavior using linear elastic fracture mechanics (LEFM), this study utilizes compact tension shear (CTS) specimens with varying loading angles. The CTS specimens provide an accurate simulation of real-world loading conditions by allowing for the application of various loading configurations, resulting in mixed-mode loading. The ANSYS Mechanical APDL 19.2 software, which includes advanced features such as separating, morphing, and adaptive remeshing technologies (SMART), was utilized in this study to precisely model the path of crack propagation, evaluate the associated fatigue life, and determine stress intensity factors. Through comparison with experimental data, it was confirmed that the loading angle had a significant impact on both the fatigue crack growth paths and the fatigue life cycles. The stress-intensity factor predictions from numerical models were compared to analytical data. Interestingly, it was observed that the maximum shear stress and von Mises stresses occurred when the loading angle was 45 degrees, which is considered a pure shear loading condition. The comparison shows consistent results, indicating that the simulation accurately captures the behavior of the AISI 316 austenitic stainless steel alloy under mixed-mode loading conditions.

Vibration Control of Flexible Manipulators by Active Cable Tension

The end point vibrations of the serial manipulator should be controlled during motion or working process. In this study the residual vibrations of the flexible manipulator were controlled with cable tensions. The finite element model was established in ANSYS Mechanical APDL. The open loop and closed loop control simulations were performed under the trapezoidal velocity motion profiles. Zero and three different initial strain values were assigned to the cables. As a result, the end point vibration amplitudes, axial forces of the cables and the bending strain values of the one element near the fixed end were observed in order to define the limitations of the sensors and actuators which will be selected for experimental setup.

Dynamic analyses of long-span cable-stayed and suspension cooperative system bridge under combined actions of wind and regular wave loads

This paper presents the dynamic analyses of long-span cable-stayed and suspension cooperative system bridge under combined actions of wind and regular wave loads. First, the wind loads acting on the bridge deck are calculated based on the aerodynamic force coefficients which were obtained in the wind tunnel and wave flume tests. Then, the wind loads acting on the bridge towers, piers and suspension cables are calculated based on the aerodynamic force coefficients which are simulated in FLUENT software. Besides, the regular wave loads acting on the composite foundations are simulated in FLOW-3D software. Finally, the dynamic responses of the bridge subjected to the combined actions of wind and regular wave loads are calculated in the Mechanical APDL module of ANSYS 17.0 software. The results indicate that the root mean square (RMS) values rather than the mean values of the time histories of the aerodynamic force coefficients obtained in the wind tunnel and wave flume tests should be selected to calculate the wind loads acting on the deck to accurately evaluate the dynamic responses of the sea-crossing bridge. The maximum RMS values of the displacement responses of the deck midspan and 5# tower top increase with the increase of the regular wave heights for the wind-wave cases, which are larger than those for the wind-only case, respectively. In general, the linear superposition of the dynamic responses under the actions of wind-only and wave-only is a conservative choice compared to the consideration of the combined actions of wind and regular wave loads. The displacement spectrums of the deck midspan and 5# tower top, and the lateral base shear and lateral base bending moment spectrums of 5# tower are analyzed to reveal the contribution mechanism of the wind loads, regular wave loads and natural frequencies of the bridge.

Совместная оптимизация конструктивных параметров индуктора и алгоритмов управления процессом нагрева под поверхностную закалку

The paper considers an approach for solving the joint optimization problem of design solutions and modes 
 of inductor functioning in the process of heating steel parts of L-shaped form for surface hardening. The first stage solves the problem of optimizing the design of the coils of the inductor and the parameters of the power supply control algorithm, ensuring the maximum uniform heating of the quenched layer to a given temperature above the Curie point in 
 a fixed time. In the second step, a phase limitation is considered, which is a technological requirement to ensure, throughout the heating stage, a temperature not exceeding the limit value. In case of violation of the specified limit, the problem of finding the control algorithm on a special interval within which the maximum temperature in the hardened layer exceeded the maximum permissible value is solved. In the third step, the problem of joint optimization is solved with the found control algorithm at a specific interval of motion on the phase restriction. The described steps can be repeated if necessary. There is presented a test example of the application of the developed strategy for the considered class of technology induction heating for the surface hardening of metal blanks with an angle zone. For the numerical solution in the MATLAB application package developed a software complex, in which integrated two-dimensional nonlinear problem-oriented model of the induction heating process, developed in ANSYS Mechanical APDL. The algorithm for solving the joint optimization problem is based on an alternate method of parametric optimization of systems with distributed parameters. Developed strategy tested on a verified model of interconnected electromagnetic and temperature fields, it is possible to obtain a uniform temperature distribution along the boundary of the hardened layer of steel semi-finished products of complex geometric shape without local overheating throughout the heating stage.

Computational methodology for the optimal design of steel truss frames integrating MATLAB and FEA platforms

Seeking to define more robust and executable structures, this article presents a computational framework for the optimal design of steel truss frames, which integrates two software of great prominence in structural engineering, MATLAB and ANSYS. Computational interfaces were created to enable the automation of the iterative optimization process. The optimization algorithm and computational interfaces were developed on the MATLAB platform, while structural analyses were performed with the ANSYS Mechanical APDL platform. Some details of the computational implementation are presented herein. The objective is to minimize the cost of structures by determining the optimal positioning of nodal coordinates and the optimal choice of commercially available structural profiles - shape and size optimization, respectively. For shape optimization, a computational model was defined to automatically generate the geometry of the structure, maintaining some intrinsic relations of symmetry and collinearity between elements. The design constraints are critical nodal displacements, stresses, and slenderness of elements, following the requirements of ABNT NBR 8800:2008. To exemplify the application of the proposed methodology, this article presents the optimal design of trusses for roofs of industrial sheds, considering its non-linear geometric behavior, typical of this type of structure.

Buckling analysis of an orthotropic cylindrical shell structure in the ANSYS Mechanical APDL software package

Buckling analysis of an orthotropic cylindrical shell structure in the ANSYS Mechanical APDL software package

Preliminary Flutter Stability Assessment of the Double-Deck George Washington Bridge

We deal with the flutter analysis of the George Washington bridge, in both the single- and double-deck configurations of 1931 and 1962, respectively. The influence of the additional lower deck on the aerodynamic behavior is investigated. To overcome the lack of aerodynamic data, a simplified approach is followed based on Fung’s formulation, in which the flutter derivatives are expressed in terms of the real and imaginary parts of the Theodorsen function and of the steady-state aerodynamic coefficients of the deck cross-section. The latter are obtained by Computational Fluid Dynamics simulations conducted in ANSYS FLUENT, whereas the ANSYS Mechanical APDL finite element package is used to perform the flutter analyses. Two different methods for the application of the aeroelastic forces are employed for the double-deck configuration: (i) self-excited forces, based on flutter derivatives related to the whole cross-section, acting on the upper deck; and (ii) self-excited forces, based on flutter derivatives related to the single deck, simultaneously applied to the upper and lower decks. The obtained results are critically compared with theoretical predictions of simple formulas available from the literature; it is suggested that laboratory tests are needed since no experimental results seem to be available.

VIBRATION ANALYSIS OF BIO-DEGRADABLE COMPOSITE WITH A NUMBER OF LAYERS

—Modern scientists are now focusing their research on materials that are naturally biodegradable and kind to the environment. Bio-composite materials formed of natural/regular fiber materials and resins, or a mixture of both, are regarded as one of the key accomplishments in the diverse field of experimental work as we are aware that concerns about natural protections are growing worldwide. The two stages of the composited make up the majority of its constituents: 1) Matrix, and 2) Binder. Natural fiber composites have received a lot of attention from scientists throughout the world due to the availability of the necessary characteristic fiber and the ease of assembly. The Mechanical APDL Analysis tool is used to create the desired model, which has different layers (3, 4, 6, and 8 accordingly). To compare the results, the natural frequencies of each individual layer are taken into consideration and documented in a tabular data format. Both eigen buckling analysis and modal analysis are successfully performed on the desired model. The reference research paper demonstrates the buckling loads for glass fiber with various layers made up of various orientations. The main objective of the project is to create a biocomposite with Bamboo fiber and Rice Husk as filler and to perform the vibration analysis with different layers and Eigen buckling analysis. Natural frequencies are obtained from vibration analysis and buckling loads are obtained from Eigen buckling analysis thus for a better understanding of the dynamic behavior of components made from fiber-reinforced composite materials, specifically for the case of plates. This study contributes to a better& more realistic understanding of the dynamical behavior of plates formed of fiber-reinforced composite materials in order to prevent structural damage imposed on or induced by undesirable vibrations.

Nonlinear Tracking Control Algorithm for Dynamical Output Systems Manipulated by the Hardly Constrained Oscillatory Actuator

In this article, a nonlinear control algorithm has been presented, in order to reduce vibrational movements of a flexible beam cantilevered in a cart supported by nonlinear stiffness, actuated by a hardly constrained second-order dynamic system. In the presented control algorithm, the interactive model of the solid body and a flexible beam has been extracted and utilized to design an algorithm, based on which the nonlinear vibrations of the tip point of the beam whose function is smooth and nonoscillatory tracking of the predefined desired trajectory are diminished. To design a nonlinear vibration control system of the beam, it has been assumed that the feedback system includes three modules: a vibrational beam cantilevered on a base, a base affected by nonlinear stiffness and actuator’s control force, and a force imposing system with constraints of bandwidth frequency limitation and actuation saturation boundary. In order to design this control system, the generalized tracking error function has been defined to nonlinearly amplify the vibrationally induced error and its rate, which by properly adjusting them, a new quantity can be extracted that satisfies the control system design constraints. To design a tracking control system for a nonlinear vibrating beam for the aforementioned three-modulus system, first, the generalized tracking error for the three modules is separately defined and parametrized, and then, by simultaneously adjusting all the defined parameters systematically, the predominant system presence in Lyapunov stability conditions is guaranteed. To illustrate the multimodule imitative (MMI) controller design algorithm, a moving support connected to a nonlinear spring and damper is considered, which carries a flexible cantilevered beam. The applied actuation system has second-order linear dynamics with the presence of command control saturation boundaries. For each of the abovementioned modules, a generalized tracking error is defined, and then, it is explained to how simultaneously adjust the parameters based on the stability and actuation constraints. The MMI controller is applied to the mentioned mechanical system modeled in the ANSYS® Mechanical APDL environment, and then, the necessary conclusions are discussed about the performance of the control system in eliminating the vibrations of the flexible arm, considering the actuation constraints while possessing the dominant Lyapunov stability.