Finite Element Analysis Approach Research Articles

The influence of stiffener geometry on flexural properties of 3D printed polylactic acid (PLA) beams

We used finite element analyses (FEA) on Abaqus to study flexural properties of additive manufactured beams using polylactic acid (PLA) polymer. Experimental stress–strain data from flexural testing are used to define elastic–plastic properties of the material in the computation software. The flexural experiments are used to validate the FEA approach suggested. The method provides good results of deflection and stress with errors well below 10% in most of the cases. Therefore, by using the proposed approach, costs related to repeated experimental works can be avoided. In addition, the flexural rigidities of the additive manufactured beams are studied. Five different beam stiffener designs (diamond, honeycomb, square, triangular and wiggle) are studied based on beam bending theory. The force–deflection data from the flexural tests are used to determine the area moments of inertia of the beams. The honeycomb stiffener showed the highest force–deflection behaviour that led to the highest calculated area moment of inertia. However, with the lowest force–deflection behaviour, the square stiffener had the lowest calculated area moment of inertia.

Gibbs–Appell method-based governing equations for one-dimensional finite elements used in flexible multibody systems

Lagrange’s equations represent the common approach in finite element analysis of an elastic multibody system. The most important step in this case is to write the governing equations. The work develops an alternative method to obtain these equations, using so-called Gibbs–Appell formalism. The advantage of this method is the decrease in the number of calculations to be made. The acceleration energy will be calculated first for a one-dimensional finite element, and then Gibbs–Appell equations are applied in the classical form. The number of differentiations required, compared to the method of Lagrange’s equations, decreases significantly, with effects on the computational time required to solve such a problem. We can assume that, due to its simplicity, this method will determine the interest of researchers in the case of large industrial applications.

Stenting-induced Vasa Vasorum compression and subsequent flow resistance: a finite element study.

Vascular stenting is a common intervention for the treatment for atherosclerotic plaques. However, stenting still has a significant rate of restenosis caused by intimal hyperplasia formation. In this study, we evaluate whether stent overexpansion leads to Vasa Vasorum (VV) compression, which may contribute to vascular wall hypoxia and restenosis. An idealized multilayered fibroatheroma model including Vasa Vasorum was expanded by three coronary stent designs up to a 1.3:1 stent/artery luminal diameter ratio (exp1.1, exp1.2, exp1.3) using a finite element analysis approach. Following Poiseuille's law for elliptical sections, the fold increase in flow resistance was calculated based on VV compression in the Intima (Int), Media (Med) and Adventitia (Adv). The VV beneath the plaque experiences the smallest degree of compression, while the opposite wall regions are highly affected by stent overexpansion. The highest compressions for Adv, Med and Int at exp1.1 are 60.7, 65.9, 72.3%, at exp1.2 are 62.1, 67.3, 73.5% and at expp1.3 are 63.2, 68.7, 74.8%. The consequent fold increase in resistance to flow for Adv, Med and Int at exp1.1 is 3.3, 4.4, 6.6, at exp1.2 is 3.5, 4.7, 7.2 and at exp1.3 is 3.8, 5.1, 7.9. Stent overexpansion induces significant VV compression, especially in the Intima and Media layers, in agreement with previously observed Media necrosis and loss in elasticity after stenting. The observed steep increase in flow resistance suggests the blood flow and associated oxygen delivery would drop up to five times in the Media and almost eight in the Intima, which may lead to intimal hyperplasia and restenosis.

A biomechanical study on the laminate stacking sequence in composite bone plates for vancouver femur B1 fracture fixation

Background and objectivesComposite bone plates are proposed for fracture fixation in periprosthetic femoral fracture. Metallic plates, having high stiffness compared to bone lead to stress shielding, reduce the compression force in the fracture site, affectthe healing process. Reduction of stiffness in the axial direction due to above reason without lowering the stiffness in transverse to avoid much of shear strain and thus avoiding instability at the fracture site leads to selective stress shielding. This can only be achieved through meticulously designed fiber reinforced composite. In the present work varied fiber orientations in the stacked laminates with varied fiber types are employed in a post-operative femur fixation for the in-silico analyses of their effectiveness using finite element analysis. MethodsIn this study a Total Hip Arthroplasty (THA) model is constructed with composite bone plates. Three-dimensional narrow type metal plate is modeled with 12 holes and length of 194 mm. Three different types of composite bone plates are modeled with 12 holes of different size for the analysis i.e. Type 1 (5.6 mm thickness and 16 mm width), Type 2 (6 mm thickness and 16 mm width) and Type 3(6 mm thickness and 18 mm width). Anatomical 3D FE models of THA with composite bone plates are constructed to find out the interfacial stresses and strains. The finite element software ANSYS is used to perform the analysis. ResultsA three-dimensional FE model of immediately post-operative femur fixation is developed and studied the maximum stress distribution, strain and movement in axial/shear direction in the metal and composite bone plate near to the fracture site. In the present study, the metal and composite plate (carbon/epoxy, glass/epoxy and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in IPO condition using FEA. ConclusionsOptimizing the fiber orientations of composite bone plates of Total Hip Arthroplasty (THA) model by controlling the biomechanical stresses could be a favorable approach. The finite element analysis approach gives a viable solution to design the composite bone plate and for designing future models that preserves the biomechanical function of THA with composite bone plate.

Experimental and numerical study on stiffness and damage of glass/epoxy biaxial weft-knitted reinforced composites

This paper deals with investigating the tensile characteristics of biaxial weft-knitted reinforced composites in terms of stiffness, strength and failure mechanism. The biaxial weft-knitted fabric was produced on an electronic flat knitting machine by E-glass yarns and then was impregnated with epoxy resin. Using an accurate geometrical model, the composite unit cell was designed in Abaqus software’s environment. Tensile tests were simulated in different directions on the created unit cell and the stiffness was calculated. By applying the proper failure theories, the composite strength was predicted and then critical regions of the unit cell were determined. In the next step, a micromechanical approach was also applied to estimate the same tensile features. Failure theories were also applied to predict the strength and most susceptible areas for failure phenomenon in the composite unit cell. The tensile properties of the produced composites were measured and compared with outputs of the finite element and micromechanical approaches. The results showed that the meso-scale finite element analysis approach can well predict the composite strength. In contrast, the meso-scale analytical equation model was not able to predict it acceptably because this model ignores the strain concentration. Both meso-scale finite element analysis and meso-scale analytical equation approaches predicted the similar locations for the composite failure in wale and course directions.

Patient-specific finite element models of the human mandible: Lack of consensus on current set-ups.

The use of finite element analysis (FEA) has increased rapidly over the last decennia and has become a popular tool to design implants, osteosynthesis plates and prostheses. With increasing computer capacity and the availability of software applications, it has become easier to employ the FEA. However, there seems to be no consensus on the input variables that should be applied to representative FEA models of the human mandible. This review aims to find a consensus on how to define the representative input factors for a FEA model of the human mandible. A literature search carried out in the PubMed and Embase database resulted in 137 matches. Seven papers were included in this current study. Within the search results, only a few FEA models had been validated. The material properties and FEA approaches varied considerably, and the available validations are not strong enough for a general consensus. Further validations are required, preferably using the same measuring workflow to obtain insight into the broad array of mandibular variations. A lot of work is still required to establish validated FEA settings and to prevent assumptions when it comes to FEA applications.

Design and performance analysis of a new optimization algorithm based on Finite Element Analysis.

Aiming at the problem that many algorithms could not effectively balance the global search ability and local search ability, a new optimization algorithm is proposed. Inspired by Finite Element Analysis (FEA) approach, a relationship of mapping between Finite Element Analysis approach and a population-based optimization algorithm is constructed through comparing the similarities and differences of FEA node and ideal particle. In algorithm framework, the stiffness coefficient corresponds to a user-defined function of the value of an objective function to be optimized, and the node forces among individuals are defined and an attraction-repulsion rule is established among them. The FEA approach that can simulate multi- states of matter is adopted to balance the global search ability and local search ability in the novel optimization algorithm. A theoretical analysis is made for algorithm parallelism. The conditions for convergence are deduced through analyzing the algorithm based on discrete-time linear system theory. In addition, the performance of the algorithm is compared with PSO for five states which include free state, diffusion state, solid state, entirely solid state, synthesis state. The simulation results of six benchmark functions show that the algorithm is effective. The algorithm supplies a new method to solve optimization problem.

Wrinkling instabilities for biologically relevant fiber-reinforced composite materials with a case study of Neo-Hookean/Ogden-Gasser-Holzapfel bilayer.

Wrinkling is a ubiquitous surface phenomenon in many biological tissues and is believed to play an important role in arterial health. As arteries are highly nonlinear, anisotropic, multilayered composite systems, it is necessary to investigate wrinkling incorporating these material characteristics. Several studies have examined surface wrinkling mechanisms with nonlinear isotropic material relationships. Nevertheless, wrinkling associated with anisotropic constitutive models such as Ogden-Gasser-Holzapfel (OGH), which is suitable for soft biological tissues, and in particular arteries, still requires investigation. Here, the effects of OGH parameters such as fibers' orientation, stiffness, and dispersion on the onset of wrinkling, wrinkle wavelength and amplitude are elucidated through analysis of a bilayer system composed of a thin, stiff neo-Hookean membrane and a soft OGH substrate subjected to compression. Critical contractile strain at which wrinkles occur is predicted using both finite element analysis and analytical linear perturbation approach. Results suggest that besides stiffness mismatch, anisotropic features associated with fiber stiffness and distribution might be used in natural layered systems to adjust wrinkling and subsequent folding behaviors. Further analysis of a bilayer system with fibers in the (x-y) plane subjected to compression in the x direction shows a complex dependence of wrinkling strain and wavelength on fiber angle, stiffness, and dispersion. This behavior is captured by an approximation utilizing the linearized anisotropic properties derived from OGH model. Such understanding of wrinkling in this artery wall-like system will help identify the role of wrinkling mechanisms in biological artery in addition to the design of its synthetic counterparts.

Machine learning predictions on fracture toughness of multiscale bio-nano-composites

Tailorability is an important advantage of composites. Incorporating new bio-reinforcements into composites can contribute to using agricultural wastes and creating tougher and more reliable materials. Nevertheless, the huge number of possible natural material combinations works against finding optimal composite designs. Here, machine learning was employed to effectively predict fracture toughness properties of multiscale bio-nano-composites. Charpy impact tests were conducted on composites with various combinations of two new bio fillers, pistachio shell powders, and fractal date seed particles, as well as nano-clays and short latania fibers, all which reinforce a poly(propylene)/ethylene–propylene–diene-monomer matrix. The measured energy absorptions obtained were used to calculate strain energy release rates as a fracture toughness parameter using linear elastic fracture mechanics and finite element analysis approaches. Despite the limited number of training data obtained from these impact tests and finite element analysis, the machine learning results were accurate for prediction and optimal design. This study applied the decision tree regressor and adaptive boosting regressor machine learning methods in contrast to the K-nearest neighbor regressor machine learning approach used in our previous study for heat deflection temperature predictions. Scanning electron microscopy, optical microscopy, and transmission electron microscopy were used to study the nano-clay dispersion and impact fracture morphology.

Femoral revision knee Arthroplasty with Metaphyseal sleeves: the use of a stem is not mandatory of a structural point of view

PurposeAlthough metaphyseal sleeves are usually used with stems, little is known about the exact contribution/need of the stem for the initial sleeve-bone interface stability, particularly in the femur, if the intramedullary canal is deformed or bowed. The aim of the present study is (1) to determine the contribution of the diaphyseal-stem on sleeve-femur interface stability and (2) to determine experimentally the strain shielding effect on the metaphyseal femur with and without diaphyseal-stem. It is hypothesised that diaphyseal-stem addition increases the sleeve-femur interface stability and the strain-shielding effect on the metaphyseal femur relatively to the stemless condition.Material and methodsThe study was developed through a combined experimental and finite-element analysis approach. Five synthetic femurs were used to measure cortex strain (triaxial-rosette-gages) behaviour and implant cortex micromotions (Digital Image Correlation) for three techniques: only femoral-component, stemless-sleeve and stemmed-sleeve. Paired t-tests were performed to evaluate the statistical significance of the difference of cortex strains and micromotions. Finite-element models were developed to assess the cancellous bone strain behaviour and sleeve-bone interface micromotions; these models were validated against the measurements.ResultsCortex strains are significantly reduced (p < 0.05) on the stemmed-sleeve with a 150 μstrain mean reduction at the medial and lateral distal sides which compares with a 60 μstrain mean reduction (p > 0.05) on the stemless condition. Both techniques presented a mean cancellous bone strain reduction of 700 μstrain (50%) at the distal region and a mean increase of 2500 μstrain (4x) at the sleeve proximal region relative to the model only with the femoral component. Both techniques presented sleeve-bone micromotions amplitude below 50-150 μm, suitable for bone ingrowth.ConclusionsThe use of a supplemental diaphyseal-stem potentiates the risk of cortex bone resorption as compared to the stemless-sleeve condition; however, the stem is not essential for the enhancement of the initial sleeve-bone stability and has minor effect on the cancellous bone strain behaviour. Based on a purely structural point view, it appears that the use of a diaphyseal-femoral-stem with the metaphyseal sleeve is not mandatory in the revision TKA, which is particularly relevant in cases where the use of stems is impracticable.

Design analysis of polysilicon piezoresistors PDMS (Polydimethylsiloxane) microcantilever based MEMS Force sensor

This study is aimed for the analysis of different designs for sensing low magnitude forces which lies in the micro-Newton range and suitable for biomimetic microbotics. For this, a flexible and high sensitive Micro Electro Mechanical System (MEMS) based Force sensor using piezoresistive sensing mechanism has been analyzed. Design analysis is carried out for sensitivity enhancement on microcantilever by incorporating various combinations of stress concentrated regions (SCR) and their respective arrays. The materials under consideration for sensor are polysilicon piezoresistors and Polydimethylsiloxane (PDMS) microcantilever. For design analysis, the designing and simulation work is assessed using Finite Element Analysis approach in COMSOL Multiphysics 5.3a software. The results revealed that the electrical sensitivity of 1.62 mV/[Formula: see text]N within (0–100) [Formula: see text]N operating range is achieved for microcantilever with rectangular SCR with square SCR array. This operating range has many applications in microbotic field such as sensing tactile movements. Hence, MEMS Force sensor for low magnitude forces has been designed with high sensitivity and flexibility.

Springback Prediction in Sheet Metal Forming, Based on Finite Element Analysis and Artificial Neural Network Approach

Sheet metal forming is one of the most important manufacturing processes applied in many industrial sectors, with the most prevalent being the automotive and aerospace industries. The main purpose of that operation is to produce a desired formed shape blank, without any material failures, which should lie well within the acceptable tolerance limits. Springback is affected by factors such as material properties, sheet thickness, forming tools geometry, contact and friction, etc. The present paper proposes a novel neural network system for the prediction of springback in sheet metal forming processes. It is based on Bayesian regularized backpropagation networks, which have not been tested in the literature, according to the authors’ best knowledge. For the creation of training examples a carefully prepared Finite Element model has been created and validated for a test case used in similar industrial studies.

WITHDRAWN: A new approach of material nonlinear finite element analysis

Abstract In this article, a novel approach is proposed for solving material nonlinear analysis problems in which a torsion problem is solved. A torsion specimen was tested in the lab and with the experimental data, shear stress and shear strain are first defined. It is to be noticed that in the basic analysis procedure, linearity assumptions are nowhere used. For example, use of shear modulus is eliminated in the basic formulation. Instead, shear stress function and shear strain functions are used as the material input. These shear stress and shear strain functions are derived from the experimental torsion-rotation data. The methodology gives ideal result, either it is linear or nonlinear range of the loading condition, with much more accuracy than the conventional linear analysis approaches. It could be realized that the methodology could be regarded as stress-based structural analysis procedure.

Load Capacity Estimation of Elliptical Contact Rolling Bearings

Bearing affiliation load capacity is one of the most important aspect while designing the bearings or while selecting it for applications. It has high influence on fatigue life prediction. Various international standards are normally used to calculate bearing load capacity; however, these standards are with predefined approaches only for the bearings with standard rolling elements and do not support for bearings with non-standard shape of rolling elements. To achieve higher load carrying capacity from elliptical contact bearing, a new bearing with concave rolling element geometry has been conceptualized and designed by the first author. The study in this paper explores different methods available for arriving at the load ratings and develops a numerical calculation; finite element analysis approach; for estimating the static and dynamic load ratings of new bearing design - high capacity elliptical contact concave roller bearing, which also called as deep groove roller bearing. The methodology is validated with the bearings that has standard shape of rolling element and known the load rating i.e. deep groove ball bearings. The numerical approach accounts the Hertzian contact pressure and orthogonal shear stresses for load rating estimation. Predicted load ratings are evaluated and compared across the results estimated from different tools

TOPSIS – Taguchi Analysis of Notch Parameters on the Fatigue Life of Super Duplex Stainless Steel

Purpose: The purpose of the current research is to quantify the impact of notch parameters viz. width, depth and central angle (perimeter length) on the fatigue life of UNS S32760 grade of super duplex stainless steel. Design/ Methodology/ Approach: Finite element analysis approach is implemented by using the popular software package ANSYS 18.1 and the experimental runs are selected as per the requirements of Taguchi L9 orthogonal array. TOPSIS approach is used along with Taguchi method to know about the impact of notch parameters and arrive at the optimal condition. Findings: It is quantitatively established that notch depth is the most critical parameter and it affects the fatigue life to a greater extent (63.4%) when compared to other factors viz. notch width (10.6%) and central angle (7.31%).

Investigation of the process parameters and restitution coefficient of ductile materials during cold gas dynamic spray (CGDS) using finite element analysis

Cold gas dynamic spray is a cold spray technique for obtaining solid-state surface coating. Several materials such as metal, metal alloys, composite materials, and polymer have been deposited successfully through cold spray onto a substrate material. A number of industrial applications for cold spray have been developed worldwide in the field of aerospace, energy, automobile, biotechnology, and military applications. In the current study, effects of various processing parameter such as impact velocity, substrate preheating temperature, a combination of different materials and coefficient of friction were used to describe the impact behaviour of ductile materials (copper, Cu, and aluminium, Al) after deposition to find a way of addressing high-strain-rate dynamic problems. The parameters were also used to verify the deposition process for the modelling of cold gas dynamic spray (CGDS) by the Lagrangian approach of finite element analysis. The results of the analysis (simulation) and that of the published experimental results in the literature correlated well. The understanding of the impact behaviour using different parameters was evident by the analysis of temperature and equivalent plastic strain (PEEQ). It was discovered that the deposition process and deformation are largely affected by particle material as compared to the substrate. A lower restitution coefficient was obtained when different materials of varying properties were combined compared to the combination of the same material. Also, the parameters under investigation do not affect the CGDS process individually, as their effects are interrelated.

FEAfix: FEA Refinement of Design Equations for Synchronous Reluctance Machines

The synchronous reluctance (SyR) machine is an attractive substitute of induction motors and synchronous permanent magnet motors, owing to its high efficiency and low cost of manufacturing. Yet, its design cannot be considered a mature topic, especially for what concerns the rotor geometry. Design equations are proposed for SyR machines by different authors, representing a good starting point and a useful guideline for designers, but they are far from giving accurate results. Conversely, the design procedures based on finite-element analysis (FEA) tend to rely on the brute force of optimization algorithms rather than on the designer's insight. In this article, a comprehensive design procedure is proposed, where design equations are complemented by the use of the iron saturation curve and the new fast FEA approach named FEAfix. This corrects the equations results via few static FEA simulations per design plane, i.e., per family of machines, rather than by FEA simulating the single machine under design. The general conclusion is drawn that the considered analytical model alone tends to overestimate torque by as much as 40% (average on the design plane). Upon augmenting equations with the saturation curve, the average overestimate drops in the vicinity of 10% error. Finally, the proposed FEAfix refinement guarantees 2% to 1% torque evaluation error, depending on the admitted computational time. High precision is, therefore, obtained while retaining the generality of the analytical approach.

Investigation of crack in beams using anti-resonance technique and FEA approach

Purpose In the case of machines, structures and assemblies, the crack generation and propagation is becoming a great concern, especially in airplane wings, turbine blades and such other applications. This is because these parts are very large in size and the crack size is very small, i.e. in microns. Hence, there is an important need to locate the crack and to find its severity before it starts to propagate and also to detect these parameters by on-site non-destructive testing methods. This paper aims to develop and test the methodology to locate an unknown single open crack in steel cantilever beam along with its severity. Design/methodology/approach This study covers analytical, numerical and experimental analysis for healthy and cracked beams. Vibration-based approach and finite element analysis (FEA) approach is used for analytical and numerical study respectively. Own designed and dedicated experimental set-up is used for testing purpose along with fast fourier transform analyzer. An anti-resonance technique is used to locate and to find the severity of unknown crack. The statistical approach helps to validate the results. Findings The comparison of the natural frequency of healthy and cracked steel cantilever beam shows that the crack in the beam reduces its natural frequency. The accuracy of results is achieved by finding actual density and Young's modulus of steel specimen under consideration. It is helpful to verify the health of the non-cracked beam by applying dye testing. The study of natural frequency and anti-resonance gives the location of crack and its depth also. The FEA approach proved to be an important tool for numerical analysis of cracked beam. Research limitations/implications The research is limited to steel material and surface cracks only. Practical implications Practically, this study highlights how to locate a surface crack in steel beam along with its depth, i.e. severity with great accuracy. Identification of the factors such as location and depth of a crack provide the severity of damage in airplane wings, turbine blades, bridges and many more, and thereby, it helps in safety at working vicinity. Social implications The identification and solutions of current research helps to predict the operational life of machine elements such as airplane wings, turbine blades, bridges and many more, and thereby, it helps in the safety of people in working vicinity of such structures. Originality/value The work presented, is based on original research and experimentation. This work is valued contribution in the field of methodologies applied for fault detection in structures and also determining its correctness by numerical and experimental work.

Non-Linear Finite Element Approach to Aerodynamic Effects on Horizontal Taut Cable

A horizontal taut cable which has application in a typical power transmission line was subjected to structural nonlinear static analysis. Finite Element Analysis (FEA) approach was employed in this study to ascertain the magnitude of tension on each node on the cable occasioned by induced aerodynamics forces. ANSYS 14.0 software helped in determining the behaviour of the system on the basis of finite element displacement method. Comparison was made between the two FEA cases with respect to the effectiveness of the analytical model which describes the response in form of a couple of degrees of freedom (DOF) while reflecting the complex features of the dynamics of the cable in reaction to the induced aerodynamic effect. In order to avert excessive displacement in the computations, it was necessary to incorporate the convergence procedure in the process. The optimum deflection of the parabolic response obtained from the analytical Finite Element Method (FEM) results in the absence of aerodynamic external effect was at the nodes 12 and 13 corresponding to cable weight of 1.002936N and cable tension of 189396.97kg/km. The cable also showed a maximum displacement of 4483.75mm for the X, Y and Z components at nodal point 2 while the minimum displacement value was 4218.75mm. The obtained result for this study revealed a complex modal behaviour as is quite expected.

Uncoupled CFD-FEA Methods for the Thermo-Structural Analysis of Turbochargers

In turbocharger design, the accurate determination of thermally induced stresses is of particular importance for life cycle predictions. An accurate, transient, thermal finite element analysis (FEA) of turbocharger components requires transient conjugate heat transfer (CHT) analysis. However, due to the vastly different timescales of the heat transfer mechanisms in fluid and in solid states, unsteady CHT simulations are burdened by high computational costs. Hence, for design iterations, uncoupled CFD and FEA approaches are needed. The quality of the uncoupled thermal analysis depends on the local heat transfer coefficients (HTC) and reference fluid temperatures. In this paper, multiple CFD-FEA methods known from literature are implemented in a numerical model of a turbocharger. In order to describe the heat transfer and thermal boundary layer of the fluid, different definitions of heat transfer coefficients and reference fluid temperatures are investigated with regard to calculation time and accuracy. For the transient simulation of a long heating process, the combination of the CFD-FEA methods with the interpolation FEA approach is examined. Additionally, a structural-mechanical analysis is conducted. The results of the developed methods are evaluated against experimental data and the results of the extensive unsteady CHT numerical method.