ANSYS Mechanical APDL Research Articles

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.

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.

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.

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.

Comparison of crack growth rates of IPE beams made from stainless steel in three-point bending

The main focus of research dealing with a fatigue of steel components is mostly performed by mechanical testing with focus set on small-scale components. On the other hand, from a civil engineering viewpoint, the steel load-bearing structures or their elements have much larger dimension, when comparing them to laboratory specimens. Therefore, the fatigue testing took place on IPE 80 specimens made from two different stainless steels AISI 304 and AISI 316, loaded in three-point bending with data collection of crack mouth opening displacement placed in mid-span using clip-on extensometer. This presented study focuses on the comparison of crack propagation rate in linear region of well-known Paris’ law. For the assessment of material constants from Paris’ equation C and m, two steel grades of stainless steel, AISI 304 and AISI 316 were experimentally obtained. To evaluate the experimental data, a three-dimensional (3D) numerical model, representing IPE 80 geometry, in a finite element method (FEM) software Ansys Mechanical APDL was created. The generated numerical results were used to evaluate stress intensity factor values, which serves as a main input to crack propagation Paris’ law.

SIMULATION OF INTERIM FORGING OF DEPOSITED PRODUCTS IN ANSYS MECHANICAL APDL (IMPLICIT ANALYSIS)

The paper considers the problem of simulating the interim forging during additive manufac-turing. Wire-arc additive technologies are associated with formation of technological residual stress fields, porosity, inhomogeneous structure and anisotropy, as well as unwanted defects, such as cracks, delamination or warping of the part. Interlayer hardening via forging both com-pensates such disadvantages and improves the mechanical properties of structures. Mathemat-ical modeling is one of main methods of studying these processes. There are a lot of publica-tions on modeling the formation of fields of residual stresses and heat shrinkage deformations in products obtained using additive technologies, including the method of wire welding. The work aims at checking the adequacy of using ANSYS Mechanical APDL for numerical modeling of interim metal forming processes. In this work, the Johnson – Cook viscoplastic model from Ex-plicit Dynamics was adapted to the capabilities of ANSYS Mechanical APDL for three materials: Amg6, 12X18H10T, VT6. As a physical model in ANSYS Mechanical APDL, a multilinear iso-tropic MISO plasticity model is chosen, which, unlike the Johnson – Cook model, does not take into account the effect of strain rate on the elastic-plastic behavior of the material. The values of the material constants for the MISO model are identified. The adequacy of replacing the non-stationary statement with a quasi-static one is proved, due to a slight loss of accuracy. A three-dimensional model of bar forging for three types of materials was built and implemented, its identification and verification were carried out by comparing with the results of a full-scale exper-iment. A good agreement between the calculated data and experiment is shown. Based on the data obtained, a conclusion was made about the admissibility of using the implicit solver ANSYS Mechanical APDL for calculating the processes of interim forging of the deposited products with acceptable accuracy.

Finite Element Analysis of Hybrid Skin Sandwich Composite

Sandwich structured composite is a particular classification in composite materials. This type of structure has been mainly used in recent studies because of its high specific strength, low density, and stiffness. It is increasingly more commonly employed in structural designs due to its features and performance. The sandwich composites used in this investigation are made of aluminium alloys and areca fibre. The sandwich composite’s face sheet comes in a variety of thicknesses. The adhesive skin layer is also varied to investigate the effect of using natural fibre. The sandwich composite is subjected to 3 point bend test. The modal analysis is investigated using the finite element method. The 3D model of sandwich composites is modelled using solid works 2020. Using Altair Hyper Works, the boundary conditions and meshing is carried out. ANSYS Mechanical APDL is used to analyse the sandwich composites. This investigation analyses the behaviour of composite sandwich beams.

Simulation of the thermo-mechanical behaviour of tread braked railway wheels by means of a 2D finite element model

The friction heat generated at the wheel-shoe interface during tread braking operations leads to a temperature rise of the wheel tread surface. Fast cooling as well as residual thermal stresses and strains can cause damages to the wheel surface, thus negatively affecting the vehicle dynamic behaviour and strongly reducing the wheel life. Modelling the thermo-mechanical interaction of the wheel-block pair is thus of paramount importance to improve the reliability of braking manoeuvres. The paper shows the development of a decoupled thermo-mechanical model and its implementation in ANSYS Mechanical APDL, which can compute the contact pressure at the wheel-shoe interface and the resulting wheel temperature field produced during braking operations, considering friction heating, air convection cooling and the rail chill effect.

Influence of connection stiffness on static-dynamic behavior of steel frames

The growing problems of excessive vibration in steel structures due to human rhythmic activities and vibrating machinery have led to the need for increasingly rigorous dynamic analysis in order to verify excessive displacements and ensure the users’ comfort. The present work aimed to carry out, via numerical simulation in ANSYS Mechanical APDL software, static, modal and harmonic analysis in steel frames with two floors and two bays in order to investigate the influence of the connection’s stiffness on the behavior of the structure. The results obtained showed that the natural frequency value of the models increases as the stiffness of the beam-column connections is increased. However, due to the harmonic analysis performed, it was not possible to delineate a behavior between the stiffness of the connections and the amplification.

3D modelling of fatigue crack growth and life predictions using ANSYS

This study uses ANSYS mechanical APDL 19.2 to predict crack propagation trajectories and fatigue crack growth at constant amplitude loading. Mixed-mode fatigue life assessment is implemented by the Paris law model for different configuration of modified compact tension specimen (MCTS) in linear elastic fracture mechanics (LEFM). The methodology includes: evaluating stress intensity factors (SIFs), a direction of crack propagation and estimating fatigue life via incremental crack growth process. Predicted crack growth path in the present analysis revealed a change in orientation of the hole proportionately affected fatigue crack life cycles. The propagation of fatigue crack is mostly attracted to the hole and the crack could either curve its path and grow towards it, or bypass the hole and propagate. The mixed-mode fatigue crack path and fatigue crack growth from this study were validated by several crack growth experimental and numerical results in literature.

Design and experimental validation of an exponentially tapering width rotational piezoelectric vibration energy harvester

The efficiency of any rotational piezoelectric vibration energy harvester (RVEH) can be improved by redesigning its host beam and making provision for self-tuning the harvester’s natural frequency with the rotational driving frequency. This article presents the design and analysis of an exponentially tapering width RVEH. The parameters for the proposed harvester’s natural frequency characteristics are acknowledged, and their effects on the peak open-circuit (OC) voltage response are discussed. A mathematical model of the system is formulated using the Euler-Bernoulli beam theory and Hamilton’s principle. Galerkin’s technique is used to acquire the system’s mass normalized mode shapes in matrix form. The proposed mathematical model is verified through ANSYS Mechanical APDL simulations and experimental methods. The harvester’s responses are obtained through MATLAB code. The two types of parameters that modify the harvester’s fundamental frequency are identified and analyzed. The proposed harvester delivered an improved power density (PD) of 5.27 [Formula: see text] and a performance amplification factor (PAF) of 3.14, operating at 7.968 Hz.

Rapid approach for structural design of the tower and monopile for a series of 25 MW offshore turbines

The goal of further reducing the Levelized Cost of Energy (LCOE) has driven the investigation of large-scale wind turbines. This work presents a simple, rapid and detailed approach for the structural design of the tower and monopile without a controller, but with frequency and high fidelity structural verification. The approach uses an optimization to reduce the mass of the structures while meeting strength, buckling and geometric constraints by using analytical equations. A verification of frequency constraints is performed with BModes, and ANSYS Mechanical APDL is used for high fidelity verification of stress and buckling. The approach is applied to study the design space of three 25 MW offshore wind turbines with different rotor diameters and cone angles, and to evaluate the nacelle center of mass fore-aft location effect. Results obtained show that the tower and monopile are more susceptible to changes in the rotor thrust than the overturning moment even for designs with high pre-cone angle and large distance of the nacelle center of mass from the tower axis. But it is possible to obtain structurally feasible tower and monopile designs for the three 25 MW turbines studied while not exceeding diameter and wall thickness limits. However, mass penalties can be decreased by 0.8-14%, to further reduce the cost of energy, by increasing the diameter limit which may require manufacturing technology development. The approach applied and studies serve to understand the design space of the tower and monopile for a 25 MW turbine, and provide baseline designs that can be used in the development of a controller and evaluation of a full suite of design load cases.

ANSYS Simulation of the Thermomechanical Behavior of a Large-Sized Composite Mandrel with Consideration of Viscoelasticity

The article addresses the modeling of the process of manufacturing a large-sized shell, given the thermomechanical behavior and viscoelasticity of the composite mandrel. The results of the experimental identification of viscoelasticity parameters of the examined material are presented. A numerical algorithm for adapting the experimental data for the ANSYS Mechanical APDL finite element analysis package is proposed. A Prony series expansion of the relaxation kernel is used as a model for describing the material behavior. The effect of temperature on the rate of relaxation processes is taken into account through the application of a temperature-time analogy according to the Williams–Landel–Ferry formula. The selected model with the calculated parameters was implanted into the commercial package of ANSYS Mechanical APDL. Simulation of two process steps of manufacturing a large-sized product was performed: winding and heat treatment of the shell. For this purpose, the quasistatic problem of mechanics and unsteady thermal conduction under conditions of convective heat transfer were solved by the finite element method. The influence of thermomechanical behavior of the mandrel material on the normal pressure acting on the mandrel surface as a function of temperature and force factors was estimated quantitatively and qualitatively. It was found that with respect to the nonlinear behavior of the composite material, the pressure level decreases by 50% compared to the case of using models of elastic behavior. This result justifies the importance of using complex models of material behavior in studying long-term technological processes, especially those associated with high-temperature effects.