3D FEA Research Articles

Modeling the influence of roughness on nanoindentation data using finite element analysis

Nanoindentation is a popular tool for the study of hardness and elasticity of materials at the nanoscale. However, the roughness of such samples may violate the basic assumptions under which these parameters can be evaluated. In this article we study the effects of roughness on the reduced modulus of contact. A systematic study using 3D FEA modeling to map the apparent modulus on a real rough surface as measured by AFM is presented. The requirements for the assessment of 2D modulus maps are compared to the requirements for the assessment of the average value and found to be much higher, approx. by a factor of ten. The possibility to use a simplified Hertzian model based on the local curvature is explored and found to give acceptable results, at least from a qualitative point of view.

Critically evaluating mechanics of structure genome-based micromechanics approach

The objective of this paper is to critically evaluate the accuracy and efficiency of a general-purpose micromechanics approach based on the Mechanics of Structure Genome (MSG), when it is applied to the constitutive modeling of 3D structures. The Generalized Method of Cell (GMC) is chosen as a reference method during efficiency evaluation. The predictions by Three-Dimensional Finite Element Analysis (3D FEA) are chosen as benchmarks during accuracy evaluation. Composites such as a continuous fiber-reinforced composite, a particle-reinforced composite, two discontinuous fiber-reinforced composites, and a woven composite are analyzed using MSG, GMC, and 3D FEA. During homogenization, MSG is found to be as accurate but much more efficient than 3D FEA, and despite high efficiency, GMC is found to sacrifice accuracy for efficiency. During dehomogenization, MSG is found to be as accurate as 3D FEA, but GMC is found not to be so accurate. The fidelity of MSG, when it is applied to the modeling of other structures (e.g., beams, plates, and shells), can be similarly evaluated.

Performance comparison between consequent‐pole and inset modular permanent magnet machines

This paper proposes some consequent-pole (CP) modular permanent magnet (PM) machines with different flux gap (FG) widths and slot/pole number combinations. The corresponding inset modular PM machines having the same magnet volume are also presented for comparison. It has been demonstrated that the output torques of the consequent pole modular machines are always higher than those of the inset modular machines regardless of FG widths and slot/pole number combinations. Other electromagnetic performances such as back-EMF, cogging torque, and iron losses etc. are calculated by 2D FEA software and compared as well. The advantages and disadvantages of consequent and inset modular PM machines are summarised here.

The Effects of Different Base Materials on the Stress Distribution of the Endodontically Treated Teeth: 3D FEA

Objectives: This study evaluated stress distrubitions formed by oblique forces in dental hard tissues, base materials and restorations of endodontically treated permanent mandibular first molars that were restored with different base materials and direct composite restorations by using 3D-FEA method.Materials and Methods: For two different restorative approaches; an MO cavity design and a MOD cavity design was created. Then root canal obturation was modeled. Composite resin (CR), conventional glass ionomer cement (GIC), fiber reinforced composite resin (FRCR), resin modified glass ionomer cement (RMGIC), flowable composite (FC), and bulk-fill composite resin (BF) were used as base materials. Von Mises, compressive and tensile stresses in enamel, dentin, base materials and final restoration were analyzed using finite element stress analysis method.Results: Regarding the resulting stresses, CR caused highest stresses and RMGIC caused lowest stresses in enamel, base material, and final restoration. RMGIC caused highest stresses and CR caused lowest stresses in dentin. It was noted that MOD cavity design caused more stress than MO cavity design for all analyzed materials.Conclusions: Materials with elastic moduli similar to dentin; FRCR and GIC, may be better choice to avoid high stresses within the tooth and restoration.

Biomechanical comparison of implant inclinations and load times with the all-on-4 treatment concept: a three-dimensional finite element analysis

The purpose of this study was to compare the effects of implant inclinations and load times on stress distributions in the peri-implant bone based on immediate- and delayed-loading models. Four 3D FEA models with different inclination angle of the posterior implants (0°, 15°, 30°, 45°) were constructed. A static load of 150 N in the multivectoral direction was applied unilaterally to the cantilever region. The stress distributions in the peri-implant bone were evaluated before and after osseointegration. The principal tensile stress (σmax), mean principal tensile stress (σmax), principal compressive stress (σmin) and mean principal compressive stress (σmin) of the bone and micromotion at the contact interface between the bone and implants were calculated. In all the models, peak principal stresses occurred in the bone surrounding the left tilted implant. The highest σmax and σmin were all observed in the 0° model for both immediate- and delayed-loading models. And the 0° and 15° models showed higher σmax and σmin values. The 0°models showed the largest micromotion. The observed stress distribution was better in the 30° and 45° models than in the 0° and 15° models.

Mechanical Characterization of 3D-Printed Individualized Ti-Mesh (Membrane) for Alveolar Bone Defects.

Individualized titanium mesh holds many advantages over conventional mesh. There are few reports in the literature about the effect of mesh pore size and mesh thickness on the mechanical properties of titanium mesh. This study is designed to develop an individualized titanium mesh using computer-assisted design and additive manufacturing technology. This study will also explore the effect of different thicknesses and pore sizes of titanium mesh on its mechanical properties through 3D FEA. According to this study, the mechanical properties of titanium mesh increased when the thickness decreased (0.5 mm to 0.3 mm). With an increase in mesh diameter (3 mm to 5 mm), the mechanical properties of mesh decreased. The diameter of titanium mesh has less influence on its mechanical properties than does the thickness of the mesh. Titanium mesh with a thickness of 0.4 mm is strong enough and causes less stimulation to mucosa; therefore, it is more suitable for clinical use. In addition, parameters of titanium mesh should be decided clinically according to bone defect size, defect location, and force situation.

Stress distribution & deflection in an Aramany class II obturator fabricated with cobalt-chromium & titanium alloys – 3D FEA

Purpose/objectivesThe aim of the research was to develop a model that accurately represents an Aramany class II defect and its obturator prostheses fabricated with Cobalt Chromium alloy & Titanium alloy to compare the deflection and the stress distribution in the rehabilitated area. MethodsAramany class II defect and the obturator prostheses was generated geometrically utilizing ANSYS 14.5, both overlaid on each other to impressionist prostheses and the maxilla as one element. Meshing of models was carried out utilizing HYPERMESH software & materialistic properties were assigned. The 120 N load was constituted on the teeth in different directions. ResultsThe stress distribution & deflection executed by ANSYS provided results that enabled the tracing of Von Mises stress and deflection field in the form of color veiled bands with standards in Mega Pascal (MPa). ConclusionThe study shows that Von Mises stresses are higher for the frame work fabricated with cobalt chromium alloy compared to Titanium alloy. The framework made of titanium alloy showed more deflection than cobalt chromium alloy. Clinical implications3D FEA can be performed on a computer without putting any stress on the human body from technical materials, which is especially difficult for maxillectomy patients.

Application of Finite Element Model in Implant Dentistry: A Systematic Review.

FEM was technologically innovated which initially aimed at answering structural analysis difficulties involving Mechanics, Civil and Aeronautical Engineering. FEM basically stands for a numerical model of analyzing stresses as well as distortions in the form of any agreed geometry. There for the shape is discretized into the so-called ‘finite elements’ coupled through nodes. Accuracy of the results is determined by type, planning and total number of elements used for a particular study model. 3-D FE model was designed for in-depth qualitative examination of the relations amongst implant, tooth, periodontal ligament, and bone. Scholarly work equating work reliability, validated with a 3-D modeling suggested that meticulous data can be acquired with respect to stress distribution in bone. Comparative results from 3-D FEA studies showed that 3D FEA, when matched with in-vivo strain gauge measurements were corresponding with clinical outcomes. The aim of this review of literature is to provide an overview to show the application of FEM in (Short) implant dentistry.

Evaluation of reliability of zirconia materials to be used in implant-retained restoration on the atrophic bone of the posterior maxilla: A finite element study.

PURPOSEZirconia materials have been used for implant-retained restorations, but the stress distribution of zirconia is not entirely clear. The aim of this study is to evaluate the stress distribution and risky areas caused by the different design of zirconia restorations on the atrophic bone of the posterior maxilla.MATERIALS AND METHODSAn edentulous D4-type bone model was prepared from radiography of an atrophic posterior maxilla. Monolithic zirconia and zirconia-fused porcelain implant-retained restorations were designed as splinted or non-splinted. 300-N occlusal forces were applied obliquely. Stress analyses were performed using a 3D FEA program.RESULTSAccording to stress analysis, the bone between the 1) molar implant and the 2) premolar in the non-splinted monolithic zirconia restoration model was stated as the riskiest area. Similarly, the maximum von Mises stress value was detected on the bone of the non-splinted monolithic zirconia models.CONCLUSIONSplinting of implant-retained restorations can be more critical for monolithic zirconia than zirconia fused to porcelain for the longevity of the bone.

An Experimental and Numerical Investigation of a Novel 3D Printed Sandwich Material for Motorsport Applications

In this paper, a novel 3-D printed core material is developed to investigate the cores structures’ strength and stiffness under bending. Using powder bed fusion, Nylon PA12 structures have been produced and CFRP skin material has been applied to the 3D printed cores. The three-point bending behaviour and failure of the developed material are compared to the commonly used Al honeycomb structure. The 3D printed re-entrant structure supported the largest load among all tested cores and showed a superior stiffness in comparison to Al honeycomb cores although the latter achieved the maximum strength and stiffness to weight ratio. Additionally, a numerical 3D FEA model has been developed to investigate the re-entrant core’s nonlinear mechanical behaviour under loading. The numerical results were in a very good agreement with the experiments in terms of the loading force, plastic deformation and the failure mode.

A Ply-By-Ply Discretized 2D FEA Approach with the Integrated XFEM-CE Strategy for Predicting Multiple Failures in Laminated Composite Structures

A Ply-By-Ply Discretized 2D FEA Approach with the Integrated XFEM-CE Strategy for Predicting Multiple Failures in Laminated Composite Structures

Are Increased Masticatory Forces Risk for Primary 2nd Molars without Successors? A 3D FEA Study.

Persistent primary teeth with healthy crown-root structures and acceptable functional and esthetic properties may be preserved over a long-term period if needed. However, they may experience root resorption, ankylosis or infraocclusion especially in the second or third decades of life. Despite a lack of sufficient detailed data, increases in occlusal forces by age are known to cause destructive stresses on root surfaces and periodontal tissue. The aim of this study was to evaluate the effect of increasing occlusal forces on mandibular persistent primary molars by using 3D finite element analysis. The impact of increased masticatory forces on compressive and tensile stresses in tooth and surrounding tissue was simulated in two different models (simulating child and adult mouths) by using 3D finite element analysis. In both models, the stress values increased by age and compressive stresses were seen on internal root surfaces, while the tensile stresses focused on the furcation area and external root surfaces. It was concluded that practices such as reducing occlusal surface width may be used to diminish the occlusal forces for long-term tooth survival in persistent primary molars.

Electromagnetic Flux Analysis of Ds Hesfm for Directly Driven Actuator Used in Aircraft Applications

This paper presents the electromagnetic flux analysis of dual stator hybrid excitation switched flux machines (DS HESFM) using segmental rotor for the directly driven electromechanical actuator aimed to use in aerospace applications. The advantage of designing a machine with directly driven system is to eliminate the intermediate gear box system with having minor component count and reduced jamming possibility. The proposed design of DS hybrid excitation with high torque density is investigated in this paper as a potential solution for aircraft applications. The key intentions of the design are high level of actuator integration to reduce the overall weight and volume and fault tolerance ability. The proposed design of DS HESFSM has simple structure, which consist of only six field excitation coils (FECs) housed in outer stator along with six armature coils (ACs) whereas, six permanent magnets (PMs) are positioned in the inner stator. Moreover, DS HESFM structure is analyzed at open circuit and short circuit conditions conditions by means of “commercial 2D FEA package, JMAG-designer ver. 14.0,” released by JSOL Corporation.

Research of an Axial Flux Stator Partition Hybrid Excitation Brushless Synchronous Generator

A vehicular generator has stringent requirements on its weight and volume. As a combination of permanent magnet and electric excitation motor, hybrid excitation machine could meet the requirements of vehicular generator, with small size, light weight, adjustable output voltage. In this paper, an axial flux stator partition hybrid excitation brushless synchronous generator (ASHG) is proposed. First, the structure and operation principle of ASHM is illustrated. Afterwards, the shape of the magnetic pole is optimized to obtain the air-gap flux density with low harmonic content. Moreover, the regulation performance of the magnetic field and output voltage are investigated by three dimensional finite element analysis (3D FEA). The result indicates that ASHG has a high performance of adjusting terminal voltage. It can improve the generator efficiency, power density and stability comparing with the conventional vehicular generator.

Determination of Mechanical Properties of Polymer Interphase Using Combined Atomic Force Microscope (AFM) Experiments and Finite Element Simulations

In polymer nanocomposites (PNCs), the physical and chemical interactions at the polymer matrix–filler interface lead to local variations in polymer properties over a substantial “interphase” region in the vicinity of the interface. Characterization of mechanical properties in the polymer interphase region is essential for informed modeling and design of advanced PNCs. Direct contact measurement of the mechanical properties in the interphase region has been performed via high-resolution scanning probe nanoindentation experiments on model polymer–substrate samples. However, the force–displacement data from indentation experiments are affected by the interaction of the elastic stress field with the substrate, which limits determination of the interphase properties close to the polymer–substrate boundary. To extract the mechanical properties of the interphase from experimentally measured data, three-dimensional finite element analysis (3D FEA) models are developed in this study to simulate the indentation exp...

Symmetric snap-through and equal potential energy load of non-uniform shallow arch under a concentrated load considering imperfection effect

This paper deals with analytical investigation of non-uniform circular shallow arch under a concentrated load considering imperfection effect under pinned-pinned boundary conditions. After characterizing the non-uniformity by three piecewise constant stiffness segments, governing equilibrium equations including imperfection effect are derived via least potential energy principle and criteria for possible occurrence of symmetric snap-through are explicitly presented by using L'Hospital's rule after identifying two modified slenderness parameters. The existence of an equal potential energy load is rigorously shown in a straightforward manner and its parametric dependence on imperfection and non-uniformity is discussed. The relationship between equal potential energy load and buckle propagation load is studied by 3D FEA of buckle propagation of corresponding non-uniform shallow panel. Moreover, two limiting cases including rigid end case and rigid center case are analyzed by employing augmented potential energy with Lagrangian multipliers. An asymptotical solution shows that a finite modified slenderness (independent of imperfection) is sufficient to ensure the occurrence of symmetric snap-through when dimension of center segment is approaching to zero in rigid end case and this conclusion holds when there is some rotational restraint at ends. For rigid center case, the closed-form criterion considering imperfection for symmetric snap-through occurrence is presented. Equal potential energy load for two limiting cases is derived and analyzed in detail. This paper is expected to enhance the understanding of stability of imperfect non-uniform shallow arch.

Simplified expressions for elastic lateral torsional buckling of wooden beams

A beam finite element formulation is developed for the elastic lateral torsional buckling analysis of wood beams with rectangular cross-sections. The formulation accounts for moment gradient, load height, and pre-buckling deformation effects. The validity of the finite element and underlying variational principle is established through comparisons with critical moments obtained by 3D FEA simulations and experimental results. The validated variational expression is then adopted to develop approximate analytical expressions that separately characterize the effects of moment gradient, partial twist restraints that may exist at beam-ends, load height, and pre-buckling deformation effects. Dimensionless coefficients were formulated to characterize each effect for simple beams and cantilevers under common loading scenarios. The derived coefficients are then consolidated into a unified framework that accounts for all effects combined to predict the elastic lateral torsional buckling capacity of wooden beams.

Analytical model of functionally graded material/shape memory alloy composite cantilever beam under bending

A new analytical model for a functionally graded material (FGM)/shape memory alloy (SMA) laminated composite cantilever beam subjected to a concentrated tip load is developed. The novelty of this work lays in the analytical modelling of moment-curvature and shear force-shear strain relations, which are derived based on ZM model and Timoshenko’s theory for all stages during loading and unloading. A high-accuracy numerical solution and a three-dimensional finite element analysis (3D FEA) for the composite beam are carried out to validate the analytical solution. The results show very good agreement in each case. The influence of gradient direction, gradient index, temperature, and relative thickness ratio of SMA to functionally graded layer on superelasticity of carbon nanotube (CNT)-epoxy-based-FGM/SMA composite beam is also examined. The results show that the superelasticity of CNT-epoxy FGM/SMA composites increased with an increase in gradient index and decreased with an increase in thickness ratio. The temperature variations induced less effect on the superelasticity of FGM/SMA composites. Furthermore the composite beam with FGM layers having the Young’s modulus graded increasingly in the inward direction exhibits a better superelastic property in comparison with that with FGM layers having the Young’s modulus graded increasingly along the outward direction.

2D-FEA Based Design and Performance Analysis of Low Weight Segmented Rotor HE-FSM for Light Weight Aircrafts

All electric aircraft (AEA), is one of the main intentions of the aerospace industry for future. Where electrical machines are capable to provide high torque density and are dominant for the feasibility of direct drive electrical driving force for aircraft applications. Besides, low weight and high torque capabilities, the best candidate solution should also inherently fault tolerant for aircraft applications. For these reasons, a new sort of machine has been familiarized and published in last decade know as flux switching machine (FSM). FSMs contain all excitation sources on stator side with robust rotor structure. According to the type of excitation, FSMs are characterized into three types such as permanent magnet PM FSM, field excitation FE FSM and hybrid excitation HE FSM. PM FSM and FE FSM use PM and FE coil for their excitation sources respectively, whereas both PM and FE coil is used in HE-FSM for excitation. Subsequently, these machines have shown high torque to weight ratios and high efficiency during research in the last decade. Therefore in this paper, a new structure of 12S-8P HE-FSM with segmental rotor has been proposed and analyzed. The proposed segmented HE-FSM has the simple structure using only three PMs and three FECs. The proposed structure is analyzed using commercial 2D FEA package, JMAG-designer ver. 14.0. This paper presents the coil test analysis of segmented HE-FSM to confirm the working principle. Besides, cogging torque, flux strengthening, torque vs current densities and power vs current densities have been analyzed and presented.

Preliminary Design Investigation of Dual Stator HE FSM using Segmental Rotor

To drop the effect of air transportation on the atmosphere as well as to advance fuel productivity more-electric aircraft (MEA) architectures is a well-known approach. As the electrical machines are competent to deliver higher torque densities and are foremost for the viability of electrical driving force for aircraft applications. For these reasons a new category of machine has been familiar and published in last decade known as flux switching machine (FSM). FSMs comprises all excitation sources on stator side without winding robust rotor structure. Additionally, FSMs are classified into three types such as permanent magnet (PM) FSMs, field excitation (FE) FSMs and hybrid excitation (HE) FSMs. PM FSM and FE FSM use PM and FE coil for their excitation sources respectively, whereas both PM and FE coil are used in HE-FSM for excitation. Afterwards, HE FSMs have shown higher torque to weight ratios with higher efficiency during research in the last decade. Yet, in existing structures of HE FSMs, there is flux cancellation between the fluxes of PMs and FE coil which causes to reduce the performance of machines. Hence, in this paper, a novel structure of dual stator (DS) HE FSM with segmented rotor has been proposed and analyzed. The main reason of dual stator is to make the separate flow fluxes in HE machines to avoid cancellations. The proposed novel DS HE FSM has a simple structure using dual stators to endorse separate dual excitations to be used in fault conditions. The proposed structure has been analyzed using commercial 2D FEA package, JMAG-designer. Initially, this paper presents the coil test analysis of proposed DS HE FSM to confirm the working principle. Besides, performance analysis has been carried out at no load and load conditions.