Finite Element Structural Analysis Research Articles

Systematic Approach for Finite Element Analysis of Thermoplastic Impregnated 3D Filament Winding Structures—Advancements and Validation

This work aims to enhance and validate a systematic approach for the structural finite element (FE) analysis of thermoplastic impregnated 3D filament winding structures (fiber skeletons). The idealized modeling of geometrically complex fiber skeletons used in previous publications is refined by considering additional characteristic dimensions and investigating their mechanical influence. Moreover, the modeling approach is transferred from the meso- to the macro-level in order to reduce modeling and computational effort. The properties of meso- and macro-level FE models are compared using the example of simple loop specimens. Based on the results, respective application fields are defined. In the next step, the same modeling approach is applied to a more complex, three-dimensional specimen—the inclined loop. For its macro-level FE model, additional material characterization and modeling, as well as enhancements in the modeling of the geometry, are proposed. Together with previously determined effective composite properties of fiber skeletons, these results are validated in experimental tensile tests on inclined loop specimens.

Nonlinear Finite Element Analysis of γ-Graphyne Structures under Shearing.

In this study, a nonlinear, spring-based finite element approach is employed in order to predict the nonlinear mechanical response of graphyne structures under shear loading. Based on Morse potential functions, suitable nonlinear spring finite elements are formulated simulating the interatomic interactions of different graphyne types. Specifically, the four well-known types of γ-graphyne, i.e., graphyne-1 also known as graphyne, graphyne-2 also known as graphdiyne, graphyne-3, and graphyne-4 rectangular sheets are numerically investigated applying appropriate boundary conditions representing shear load. The obtained finite element analysis results are employed to calculate the in-plane shear stress–strain behaviour, as well as the corresponding mechanical properties as shear modulus and shear strength. Comparisons of the present graphyne shearing response predictions with other corresponding estimations are performed to validate the present research results.

Nonlinear Finite Element Structural Analysis of Reinforced Concrete Beams with out of Plane Parts

The purpose of this study was to investigate and compare the structural behavior of the reinforced concrete beams contain out of plane parts with the straight beam by finite element analysis (FEA) using ABAQUS software package. The studied models were evaluated by comparing their results with previous experimental results of the research done by the same authors. The study focused on the effects of the number of the out of plane parts on the beams' mid span deflection, the cracking and ultimate loads, and failure mode. The obtained results showed that load bearing capacity of the beams with one, two, and three out of plane parts was lower than the capacity of the straight beam by about 35%, 33%, and 68%. In addition, the results of the beams with an even number of out of plane parts were generally better than the results of those with odd number, and the increasing number of out of plane parts changed the failure mode from flexure to combined flexure plus torsion. Finally, the FEM analysis was comparable with those obtained from the experimental procedures with an average difference ratio not exceeding 5% in the ultimate load and 7% in the deflection.

Finite Element Analysis of Silver Nanorods, Spheres, Ellipsoids and Core-Shell Structures for Hyperthermia Treatment of Cancer.

The finite element analysis technique was used to investigate the suitability of silver nanorods, spheres, ellipsoids and core–shell structures for the hyperthermia treatment of cancer. The temperature of the silver nanostructures was raised from 42 to 46 °C, in order to kill the cancerous cells. The time taken by the nanostructures to attain this temperature, with external source heating, was also estimated. The heat transfer module in COMSOL Multiphysics was used for the finite element analysis of hyperthermia, based on silver nanostructures. The thermal response of different shapes of silver nanostructures was evaluated by placing them inside the spherical domain of the tumor tissue. The proposed geometries were heated at different time intervals. Optimization of the geometries was performed to achieve the best treatment temperature. It was observed that silver nanorods quickly attain the desired temperature, as compared to other shapes. The silver nanorods achieved the highest temperature of 44.3 °C among all the analyzed geometries. Moreover, the central volume, used to identify the thermal response, was the maximum for the silver nano-ellipsoids. Thermal equilibrium in the treatment region was attained after of heating, which made these structures suitable for hyperthermia treatment.

AN EXPEDITIOUS PARAMETRIC APPROACH FOR CITY INFORMATION MODELING AND FINITE ELEMENT ANALYSIS

Abstract. The mitigation of seismic risk passes through the assessment of seismic hazard of urban fabrics on a given territory. Statistical methods and damage probability matrices are currently used to facilitate seismic safety knowledge and assessment operations. These methods, despite being fast and low cost, often return results that differ from reality and prone to the expertise of the operator. Indeed, in order to have more accurate information it is necessary to conduct Finite Element Analysis (FEA). However, this type of analysis requires considerable surveying and modeling time and therefore are not easily applied to the urban scale. The key to implement this analysis at the territorial scale lies in the way of acquisition of urban data (geometric and informative) and their management within appropriate modeling environments that allow their treatment. Currently, the information modeling paradigms used for urban data collection and management are either time and resource consuming (HBIM) or overly simplified (GIS). In this research we investigate the potential of City Information Modeling (CIM) in a parametric environment (with reference to CityGML standards) combined with urban survey procedures. Aim of the work presented here is the definition of a parametric modeling protocol that allows, in a short time, the acquisition, modeling and finite element structural analysis of urban aggregates.

Effect of Restorative Crown of Different Cuspal Inclination and Occlusal Contact on Stress Distribution in Mandibular Second Premolar with Different Ferrule Configuration and Peripheral Bone- 3D Finite Element Analysis

Background: Restoration of pulpless teeth have been difficult because of coronal loss from dental caries, diminished moisture content, endodontic therapy and fractures, resulting in prone to fracture of the tooth during function. Cast metallic band enclosing around cervical surface of a tooth is called ferrule. The role of ferrule is to assist in strengthening the endodontically treated tooth.
 Purpose: In case of ferrule less tooth, the post performs as a wedge and may result in root fracture. Therefore modification in design of ferrule is required. Presence or absence of ferrule of coronal dentin influenced stress distribution pattern within tooth structure. Failure or success of a restoration may be influenced by on how the stress is dispersed to the tooth structure so it is essential to study the stress dispersal pattern within tooth and associated structure.
 Materials and Methods: A three-dimensional FE method (FEM) will be carried out for study and finite element structural analysis programs will be HYPERMESH 11 and ANSYS 18.1 software. Eight 3D models will be created to simulate endodontically restored mandibular second premolar with different coronal dentin configurations. The complete crown will be modeled with a 20-degree, 33- degree, 45-degree facial cusp inclination. The oblique force of 200 N will be executed to the buccal cusp of mandibular second premolar. Analysis of results will be done by both color-coding and numerically. By using FEA software the von Mises equivalent stress (MPa) will be calculated.

Aeroelastic Analysis of a Single Element Composite Wing in Ground Effect Using Fluid–Structure Interaction

Abstract This work focuses on an advanced coupling of computational fluid dynamics (CFD) and structural finite element analysis (FEA) on the aeroelastic behavior of a single element inverted composite wing with the novelty of including the ground effect. The front wing of the formula one (F1) car can become flexible under the fluid loading due to elastic characteristics of composite materials, resulting in changing the flow field and eventually altering overall aerodynamics. The purpose of this study is to setup an accurate fluid–structure interaction (FSI) modeling framework and to assess the influence of elastic behavior of the wing in ground effect on the aerodynamic and structural performance. Different turbulence models are studied to capture better the changes of the flow field and variation of ride heights are considered to investigate the influence of ground effect on aerodynamic phenomena. A steady-state two-way coupling method is exploited to run the FSI numerical simulations using ansys, which enables simultaneous calculation by coupling CFD with FEA. The effect of various composite structures on the wing performance is extensively studied concerning structure configuration, ply orientation, and core materials. The numerical results generally represent good agreement with the experimental data, however, discrepancy, especially in the aerodynamic force, is presented. This may be a consequence of a less effective angle of attack due to the wing deflection and deterioration of vortex-induced effect. For the structural analysis, the woven structure gives rise to more stable structural deflection than the unidirectional structure despite the associated weight penalty.

Low‐Temperature Synthesis of Amorphous Silicon and Its Ball‐in‐Ball Hollow Nanospheres as High‐Performance Anodes for Sodium‐Ion Batteries

AbstractSilicon is widely developed and deemed as a hopeful anode material for lithium‐ion batteries. However, till now there is very little literature devoted to its study for sodium‐ion batteries (SIBs). One possible reason is the preparation difficultly of carefully crafted amorphous silicon (a‐Si) structures by a facile and low‐cost method. Another reason is that a‐Si suffers from large volume expansion, slow sodium diffusion kinetics, and poor electrical conductivity. Herein, a new method called as “sodiothermic reduction” is used to prepare a‐Si hollow nanospheres at a much lower temperature. Moreover, an a‐Si‐based composite with yolk‐shell structure is designed via atomic layer deposition of alumina, in situ chemical polymerization of pyrrole, and dilute HCl etching. The obtained composite as an anode material for SIBs displays a great initial discharge capacity of 645.6 mAh g–1 at 100 mA g–1, superior long steadiness up to 5000 cycles at 800 mA g–1, and preeminent rate capability (646.4, 193.5, 138.6, 105, 77.5 mAh g–1 at 100, 400, 800, 1500, 3000 mA g–1, respectively). In situ transmission electron microscopy observation on the structure evolution and finite element analysis of the stress–strain behavior are combined to further prove the merits of the well‐designed yolk–shell structure.

A Geomatics Approach in Scan to FEM Process Applied to Cultural Heritage Structure: The Case Study of the “Colossus of Barletta”

Artistic, architectural and Cultural Heritage (CH) structures are often exposed to a high risk of damage caused by seismic events, natural disasters and more by negligence and poor state of preservation and conservation; the use of a series of technologies, based on digital acquisition and high-level data processing, allows the realisation of a three-dimensional model of high detail. In order to preserve structures of particular historical and architectural value, it is necessary to assess their structural stability. In addition, many structures, such as statues, have rather complex geometries. Therefore, it is necessary to identify a methodology able to transform the point cloud generated through a geomatics approach into a model suitable for FEM (Finite Element Analysis) analysis. This process, known as Scan to FEM, is addressed in this paper. The paper shows the case study of the “Colossus of Barletta”, a bronze statue dating back to the 5th century A.D. located in the city of Barletta, Italy. To analyse this structure, a suitable methodology has been developed which is based on the optimisation of the surface model of the structure; in this way, it is possible to obtain an efficient transformation from a digital photogrammetric model with complex geometry into a model suitable for structural finite element analysis. The digital photogrammetry technique was applied for the survey of the structure, which allowed us to obtain a very high-resolution dense point cloud and a geometrically accurate three-dimensional mesh model, i.e., in a TIN (Triangulated Irregular Network) model. Subsequently, the TIN was transformed into a quad mesh model (identifying a suitable reduction value) and finally into NURBS (Non-Uniform Rational Basis-Splines) to be optimised and imported into a finite element calculation software. This geomatics approach has validated an efficient Scan to FEM process; in fact, thanks to this methodology, it is possible to elaborate three-dimensional models with complex geometry and draw a series of considerations related to structural behaviour or specific restoration interventions.

Analysis of a Celestial Icosahedron

AbstractThis paper presents the experimentation and finite-element analysis of a unique structure called a celestial icosahedron. The structure is being considered in a project related to lighter-t...

Research on electrical strain gages and experimental stress analysis: Case study for a full wheatstone bridge

This study investigated electrical strain gage technology, which is widely used in experimental stress measurement, on an application. Strain gages are used to precisely measure strain directly in a system. This method is carried out to verify the numerical and analytical calculations performed or to record the strain data generated during the active duty of a system and to investigate the fatigue damage. In particular, verifying numerical calculations in the strength-material recovery optimizations of mass-produced systems contributes to the development of the system. In this study, strain measurement using strain gage and strain measurement technology is presented on an application. Information was given about strain gages. A full bridge wheatstone bridge consisting of 4 linear gages was created on a prototype. The system was tested with a load cell validation. Structural finite element analysis of the prototype and analytical calculation of the fullbridge strain gage connection were performed. The results showed that the measurement with the strain gauge differed 1.20% and 1.40% from the analytical and numerical results, respectively. Thus, precision strain measurement technology was successfully presented in engineering systems.

Structural FEA-Based Design and Functionality Verification Methodology of Energy-Storing-and-Releasing Prosthetic Feet

The prosthetic feet that are most often prescribed to individuals with K3/K4 levels of ambulation are the ESR feet. ESR stands for energy-storing and -releasing. The elastic energy is stored by the elastic elements in composite materials (carbon fiber or glass fiber). ESR feet must be developed and optimized in terms of stiffness, taking into account the loads that a healthy human foot undergoes and its kinematics while walking. So far, state-of-the-art analyses show that the literature approaches for prosthetic foot design are not based on a systematic methodology. With the aim of optimizing the stiffness of ESR feet following a methodological procedure, a methodology based on finite element structural analysis, standard static testing (ISO 10328) and functional verification was optimized and it is presented in this paper. During the path of optimization of the foot prototypes, this methodology was validated experimentally. It includes the following: (i) geometry optimization through two-dimensional finite element analysis; (ii) material properties optimization through three-dimensional finite element analysis; (iii) validation test on physical prototypes; (iv) functionality verification through dynamic finite element analysis. The design and functional verification of MyFlex-γ, a three-blade ESR foot prosthesis, is presented to describe the methodology and demonstrate its usability.

The analyses of frictional losses and thermal stresses in a diesel engine piston coated with different thicknesses of thermal barrier films using co-simulation method

This study comparatively presents the thermal and mechanical effects of different Thermal Barrier Coatings (TBCs) and their thicknesses on the performance of aluminum diesel engine piston by combining Finite Element Analyses (FEA) and Artificial Neural Network (ANN) methods. The piston structure of MWM TbRHS 518S indirect injection six-cylinder diesel engine was modeled. The clustered TBCs (NiCrAlY–Gd2Zr2O7, NiCrAlY–MgO-ZrO2, NiCrAl–Yttria Partially Stabilized Zirconia (YPSZ), and NiCrAlY–La2Zr2O7) were implemented to the related surface of aluminum alloy piston and then static, thermal, and transient structural FEA were conducted for each model. Based on both of the temperature and equivalent stress distributions, NiCrAlY–Gd2Zr2O7 coated model displayed the best performance. Additionally, the effects of top coating thicknesses of TBCs were investigated in the range of 0.1–1.0 mm with 0.1 mm increments in FEAs. The thermally effective top coating thickness was predicted as 0.95 mm for the selected TBC using ANN method. Then the effects of coating thickness on frictional performance were revealed by generating transient structural FE models and utilizing stribeck diagram. The uncoated and 0.95 mm NiCrAlY–Gd2Zr2O7 coated models were adjusted as transient and the related crank angle – dependent in-cylinder combustion pressure data was implemented. The friction force was reduced by at least 15% in NiCrAlY–Gd2Zr2O7 coated model.

An efficient exponential based integration for von Mises plasticity combined with Lemaitre damage model

In elastoplastic problems, integrating the constitutive equations decides the final state of stress and the related plastic variables. Integration based on exponential-mapping strategy is a new and promising method to fulfill the task and has not been implemented for the problems of damage mechanics yet. For the first time, here, the exponential-mapping technique is developed for the elastoplastic finite element analyses of structures combined with Lemaitre damage model. Subsequently, the associated stress-updating algorithm is presented to clearly show the process of finding stress and its pertinent variables during a nonlinear finite element analysis with the derived method. Afterwards, an extensive range of numerical tests is carried out to evaluate the performance of the suggested formulae including verification, precision, convergence rate, and efficiency investigations. Consequently, the outcomes demonstrate a high level of performance by the new algorithm to solve the fundamental elastoplastic equations and update the stress in nonlinear finite element analyses.

Multilinear model for progressive collapse response of reinforced concrete frames under penultimate column removal scenario

When local damage occurs due to unexpected events, compressive arch action (CAA) and catenary action (CTA) increase the progressive collapse resistance beyond the conventional plastic hinge mechanism. To investigate the progressive collapse behavior, large-scale structural tests and/or finite element analysis are performed, which are time-consuming and requires in-depth professional knowledge. In the present study, a multilinear model was developed to evaluate the progressive collapse resistance of moment sub-frames after the removal of a penultimate column. To estimate the load-carrying capacity and corresponding deformation at each mechanism, the effects of boundary condition, and the geometric and material properties of the beam section on the structural performance were considered. The validity of the proposed method was verified by comparison with the existing test results of moment sub-frames under progressive collapse. Further, a parametric study was performed to investigate the effects of concrete strength, reinforcement ratio, beam section size, and beam span on the progressive collapse resistance of the substructure. The analysis results showed that increasing the beam depth or beam top rebar ratio significantly increased the progressive collapse resistance.

Finite Element Analysis of Vertical and Horizontal Drainage Structures under Vacuum Combined Surcharge Preloading

Combined vacuum and surcharge preloading has gradually been widely used because of its advantages of low cost, green environmental protection, and good treatment effect. The conventional prefabricated vertical drain presents obvious defects in vacuum preloading treatment, such as obvious silting, serious bending of the drainage board, large attenuation of vacuum degree of drainage board along the depth, long construction period, and so on, which affect the final reinforcement effect. In this paper, the MIDAS finite element simulation of combined vacuum and surcharge preloading of prefabricated vertical drains (PVDs) and prefabricated horizontal drains (PHDs) is established through the comparative experiment of the engineering field. The comparative experimental study is carried out from the aspects of the vertical settlement, horizontal displacement, and pore water pressure. The results show that under combined vacuum and surcharge preloading, the consolidation effect of soft soil with PHDs is better than that with PVDs. When PHDs are used, the vertical settlement increases by 7.2% compared with PVDs; the horizontal displacement is larger; and the pore water pressure dissipates faster. This is because when the PHDs are adopted, the consolidation direction of the soil is consistent with the direction of the vacuum suction, which is mainly caused by vertical settlement. With the consolidation, the spacing between PHDs is gradually shortened, and the drainage distance is reduced, which can effectively reduce the consolidation time and improve the reinforcement effect of the soil. In addition, the PHDs can move downward uniformly with the soil during the consolidation process and have almost no bending deformation, which makes the vacuum transfer more uniform and effective.

Thermal and structural behavior of cold-formed steel frame wall under fire condition

Light gauge Steel Frame (LSF) system, are extensively used in residential, commercial and industrial buildings. Its growing popularity in building construction industry is due to several advantages over other construction materials such as light weight, high strength and stiffness, uniform quality, ease of prefabrication and mass production, economy in transportation and handling. Fire safety of cold-formed steel structures has become more important since cold-formed thin-walled steel sections heat up quickly under fire condition (high section factor and high thermal conductivity) and present low fire resistance. LSF wall systems are used as primary load bearing structural members providing strength and stability in multi-story LSF buildings. Therefore a better understanding of the fire performance of LSF wall systems is required. The structural behavior of the LSF walls at high temperatures depends on the temperature distribution at the wall component and the mechanical property of cold-formed steel and other materials used in LSF walls at elevated temperatures. Also, the thermal performance of the LSF wall is influenced by its components, including the stud cross-section, stud size, sheathing, and insulation types and their thicknesses, and thermal properties of them. In this paper, a numerical study was undertaken using the finite element program ABAQUS. The structural finite element analysis were conducted under transient state condition using the time–temperature profiles of wall components obtained from the thermal analysis. The finite element thermal and structural models were first validated by comparing their results with the previous test results and then a parametric study was conducted with considering the effect of various parameters such as type of sheathing and its arrangement, stud web depth, stud flange width, and stud cross-section shape. The temperature distribution and time–temperature profile of the wall component and Fire-Resistance Rating (FRR) of the wall have been calculated. The results showed that sheathing is one of the most critical factors in fire resistance of walls and has a significant influence on the FRR of walls and increasing the stud depth affects the thermal and structural behavior of the LSF wall and leads to an increase in the FRR of the wall against fire. Also, increasing the stud flange width of LSF wall does not affect the thermal behavior and temperature distribution of the wall, but leads to an increase in the FRR of the wall against fire. The stud cross-section shape does not affect the temperature distribution in the cross-section but can affect the wall’s behavior under fire conditions.

Stress reduction and wafer bow accommodation for the fabrication of thin film lithium niobate on oxidized silicon

Sub-micrometer-thick lithium niobate on an insulator is a promising integrated photonic platform that provides optical field confinement and optical nonlinearity useful for state-of-the-art electro-optic modulators and wavelength converters. The fabrication of lithium niobate on insulator on a silicon substrate through ion slicing is advantageous for electronic-photonic integration but is challenging because of debonding and cracking due to the thermal expansion coefficient mismatch between silicon and lithium niobate. In this work, the fabrication of thin film lithium niobate on insulator on a silicon handle wafer is achieved, informed by structural modeling, and facilitated by accommodating for dissimilar wafer bows using a bonding apparatus. Structural finite element analysis of strain energy and stress, due to thermal expansion coefficient mismatch at elevated temperatures, is conducted. High strain energies and stresses that result in debonding and cracking, respectively, are studied through modeling and reduced by selecting optimized substrate thicknesses followed by an experimental technique to bond substrates with dissimilar bows. A lithium niobate thin film with a thickness of 800 nm is successfully transferred to an oxidized silicon wafer with a root mean square surface roughness of 5.6 nm.

Efficient second-order nonlinear finite-element simulation of concrete-filled FRP tubular arches

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are attractive as beams and arches in harsh environments due to their durability and ease of erection. A successful infrastructure application is the use of multiple, buried CFFT arches in short-span bridges. To effectively analyze and design CFFT arches under complex loadings, there is a need for numerical procedures that capture the structural behavior of CFFT arches including the effects of FRP confinement on the concrete core and second-order response. Here, a computationally efficient structural finite-element analysis technique for the second-order inelastic behavior of these CFFT arches is detailed. A curved, flexibility-based, layered-frame element is employed to handle geometric and material nonlinearities. A concrete constitutive model that explicitly considers the effect of dilation of the concrete core and confinement provided by the FRP tube is implemented. A bending test was performed on a CFFT arch, and experimental data compared with model predictions. Additional comparisons are made with CFFT arch and beam bending tests available in the literature. The model is shown to accurately predict the load-carrying capacity and ductility of CFFT members, and to capture arch collapse mechanisms arising from FRP rupture and concrete crushing.

Investigation of the right first-time distortion compensation approach in laser powder bed fusion of a thin manifold structure made of Inconel 718

The research work first demonstrates modelling techniques for distortion prediction of laser powder bed fusion (LPBF) using the inherent strain approach implemented in structural finite element analyses. The prediction of distortion is compared with experimentally measured results of a thin manifold structure made of Inconel 718. The predicted distortions were used to verify the right first-time approach for distortion compensation where the thin manifold structure was first simulated. The distortion was then compensated using mapping techniques across different source meshes, and the component was finally manufactured using LPBF. Two components were built, one with compensation and one without compensation. The results showed that the right first-time approach compensated the distortion for the majority of the part. There were areas where the compensation was not accurate due to overpredictions of the distortion.