Finite Element Analysis Techniques Research Articles

Effect of Thermal Response and Vibration on the Multicracked Rotor Immersed in a Fluid Medium Using Finite Element Method

A rotor shaft under high rotating speeds and heavy loading may establish fatigue damage in terms of cracks due to the long duration of the operation. Analysis of the size and location of the crack in the rotor shaft becomes very difficult, especially while the rotor shaft revolves in a viscous fluid medium. This research is an attempt to measure the vibration signature of a multicracked cantilever rotor shaft with additional mass at the free end in a different fluid medium at a finite region. The dynamic response of a cracked cantilever rotor shaft, with additional mass at the free end, partly immersed in air and diverse viscous mediums are measured experimentally. The existence of open cracks in the rotor shaft in both transverse directions, along the crack and perpendicular to the crack, was considered. The experimental analysis is performed to examine the variation in vibration response with varying the size of the rotor shaft, crack depth, and fluid properties. The finite element analysis technique is employed by using ANSYS to authenticate the vibration response of the same multicracked cantilever rotor shaft in air and different viscous mediums.

Buckling Analysis of Laminated Composite Plate Using FE Method

Abstract: This study investigates the use of finite element analysis to composite plate structures. The major purpose of this research is to use FEA techniques to evaluate the buckling behavior of composite plates. FEA simulation and CAD modeling are both possible with the help of ANSYS APDL. It has been determined that carbon composite is a material and that the individual plates may take on either a hexahedral or a quadrilateral geometry. The buckling load of the plate is determined by applying the structural loads on it. The FEA is performed for all permutations, which include changing the h/b ratio from 0.08 to 0.16 and then from 0.16 to 0.24. The buckling load is determined by the eigenvalues and is different for each h/b ratio. According to FEA predictions, increasing the h/b ratio increases the buckling load. The findings of this study suggest that finite element analysis (FEA) may be utilized to enhance the design of composite structures subjected to a wide range of loading scenarios.

Multifunctional Structure Calibration by Optimal Measurement Using Hybrid Approach for Response Monitoring

Multifunctional structure calibration by optimal measurement using hybrid approach is developed for the conventional strain gauges for response monitoring. In the hybrid calibration approach, we have used the finite element analysis and experimental modal technique to quantify the measured output of distributed sensors. Smart materials such as piezoelectric (PZT and PVDF) in thin film form are widely appreciated for distributed sensing application in composite structures. The light weight composite structures can be made multi-functional by incorporating the piezoelectric materials to have non-structural functionalities such as sensing, actuation, energy harvesting and health monitoring. In the present study, in addition to load carrying and damping, which are the essential structural functions, the composite plate is made to have self sensing capability with four distributed strain gauges and PZT patches respectively. Further, it has been shown that using a single strain measurement, the finite element strains can be updated at different assumed strain gauge locations in order to calibrate the PZT patch sensors placed nearby to output engineering strains.

NUMERICAL ANALYSIS OF SEISMIC RESPONSE OF STEEL CYLINDRICAL LNG STORAGE TANKS

Numerical analysis of the seismic response of steel cylindrical LNG (liquified natural gas) storage tanks is essential to designing such structures to ensure their safety and structural integrity during earthquake events. The seismic analysis involves the assessment of the tank's response to ground motion and evaluating its structural performance under seismic loads. The LNG storage tanks' seismic behavior is rarely reported when the tank is subjected to strong earthquakes. This paper evaluates the vibration characteristic (modal analysis) and the seismic response analysis, e.g., time history response, displacement vs. time, and distribution of the maximum Von-Mises stresses of the perfect cylindrical storage tanks. This paper uses the finite element analysis (FEA) technique using ABAQUS CAE-2019 to evaluate the seismic capacity in peak ground acceleration (PGA). Three perfect cylindrical tanks (PCT) have been considered first for modal analysis, with two having high-yielding strength and the rest with low-yielding strength. Then El-Centro 1940 seismic waves are applied as a horizontal ground motion at the fixed base of the tanks. Finally, the results from the modal analysis regarding the first natural frequency of the tank models are compared with those obtained from experiments. The result’s comparisons illustrate that the numerical simulation agrees well with the experimental test results.

Numerical Investigation of Cracks at Girder Ends of Prefabricated Post-Tensioned Prestressed Concrete I-Girders

Prefabricated post-tensioned prestressed concrete (PTC) girders with high degrees of prestressing have been developed continuously in recent bridge designs to reach longer spans, higher quality, and larger load-bearing capacity. However, during the prefabrication process, several inclined and horizontal cracks were observed at the ends of a new style post-tensioned concrete girder, which could have a negative impact on the girders' longevity. In this study, a nonlinear finite element analysis technique was utilized to illustrate how concrete reacts and the mechanisms behind typical cracking patterns during the actual post-tensioning sequence. The prestressing load of a PTC girder was simulated with an improved cooling temperature method that accounts for immediate prestress losses. The field of principle tensile strain patterns and primary strain trajectories explained the overall mechanism underlying typical cracking behaviors. The results showed that the horizontal cracks under the anchorage plate (behavior 1) were generated by the bursting force, whereas the inclined cracks (behavior 2) and the horizontal cracks between the strands N1 and N2 anchor plates (behavior 3) were caused due to the spalling force. The effects of self-weight, girder end forms, as well as the transfer length of the prestressing strands, were discussed. The result demonstrates that both the self-weight and girder end shapes have a considerable effect on the behaviors of the anchorage zone. It is suggested that the transfer length of the anchor head be greater than 26 times of strand diameter to achieve the same effective stresses as the theoretical values.

Structural optimization of pitch bearings for offshore wind turbines

Pitch bearings are key components for the pitch system of wind turbines, and their reliability is closely associated with normal operation of wind turbines. In this paper, to solve the low efficiency problem of the GH Bladed and MATLAB software in design and analysis due to its operation in a single-user, stand-alone and single-key mode, GH bladed and MATLAB were combined based on Python for the integrated load spectrum calculation of pitch bearings through the full life cycle. Based on theories of contact strength analysis and fatigue life, finite element analysis and sub-modelling refinement techniques are established to investigate the relation between structural parameters and raceway stress of the bearings. Based on the Artificial Fish Swarm Algorithm (AFSA), the structural parameters are optimized to minimize the maximum contact stress on the bearing raceways and maximize the fatigue life of the bearings. The results show that the maximum contact load and the maximum contact stress on the pitch bearing raceways are significantly reduced and the bearing fatigue life is notably increased by 8.7%. The method proposed in the present study applies not only to pitch bearings, but also to other large four-point contact ball bearings.

A Finite-Element Method for Enhancement Issues of Frame of Battery Operated Ridge Planter with Drip Line Installer

Using distinct partial differential equations, complicated structures breaks down into small elements using the computational approach known as finite element analysis (FEA). Engineers in agriculture can investigate the behavior of numerous input products using numerical simulation based on the FEA technique in order to enhance the design of any machine without constructing a prototype. The current study employed the FEA technique to develop and simulate the frame of a battery-operated ridge planter with a drip line installer. A static structural test was performed through using the FEA technique in the ANSYS version 15.0 workbench software, and a 3D-CAD model of the frame of a battery-operated ridge planter with drip line installer was made using the Solid Works software. To determine the force necessary in the universal testing machine and the applied forces, respectively, on the frame, a specific fixture has been generated.
 Total deformation was measured at 23313 mm, and the simulation revealed that the maximum shear stress, equivalent stress, normal stress, stress intensity, and strain energy were, respectively, 8.40 MPa, 16.68 MPa, 16.4 MPa, 16.8 MPa, and 3.55 MPa at 1817.5 N of total load acting on the frame.
 The stress values are within the material's yield strength, it was also observed. The FEA methodology was discovered to be a way for creating and simulating the frame of a battery-operated ridge planter with drip line installer that is very effective and scientific.

Estimating elastic modulus using experimental data without strain measurement device and optimization technique of finite element analysis

Estimating elastic modulus using experimental data without strain measurement device and optimization technique of finite element analysis

Effect of welding current on the microstructural evolution and lap-shear performance of resistance spot-welded 340BH steel

In this study, we used experimental characterizations and finite element analysis (FEA) techniques to investigate the effect that welding current exerts on the microstructural features and mechanical properties of bake-hardened (BH) steels. Resistance spot welding (RSW) experiments were conducted using 5.0 and 7.0 kA of welding current. The microstructure across the weld regions was analyzed using optical microscopy (OM) and electron backscatter diffraction (EBSD). FEA was employed to simulate the RSW process, predict nugget dimensions, and determine cooling rates. The results of the OM analysis showed that nugget size increased with an increase in the welding current, and EBSD characterization revealed similar microstructures under both levels of current, but significant variations were observed within weld zones. Lath martensite formed as a result of rapid cooling in the fusion zone (FZ). Whereas, fine and coarse grains were found in the heat-affected zone (HAZ). In addition, the formation of lath martensite in the FZ resulted in high hardness on a 2D map of microhardness. The welding current had no substantial effect on microhardness, but it did impact the mechanical properties under lap-shear test conditions, which resulted in significant changes in the fracture mode. The deformation and fracture behavior of spot-welded specimens was studied using a lap-shear test coupled with 3D digital image correlation (DIC). The experimental results indicated a fracture in the 5.0 kA current samples near the FZ/HAZ boundary, while 7.0 kA welding current resulted in base metal (BM) necking and tensile fracture. FEA was also employed to elucidate the local deformation properties and fracture modes during lap-shear testing. The results of this study show that nugget size has no effect on a failure site during lap-shear loading, but size does affect the nugget load-carrying capabilities. The failure behavior was influenced by the microstructural properties of the distinct weld areas.

Quantitative Full-Field Data Fusion for Evaluation of Complex Structures

BackgroundValidation of models using full-field experimental techniques traditionally rely on local data comparisons. At present, typically selected data fields are used such as local maxima or selected line plots. Here a new approach is proposed called full-field data fusion (FFDF) that utilises the entire image, ensuring the fidelity of the techniques are fully exploited. FFDF has the potential to provide a direct means of assessing design modifications and material choices.ObjectiveA FFDF methodology is defined that has the ability to combine data from a variety of experimental and numerical sources to enable quantitative comparisons and validations as well as create new parameters to assess material and structural performance. A section of a wind turbine blade (WTB) substructure of complex composite construction is used as a demonstrator for the methodology.MethodsThe experimental data are obtained using the full-field experimental techniques of Digital Image Correlation (DIC) and Thermoelastic Stress Analysis (TSA), which are then fused with each other, and with predictions made using Finite Element Analysis (FEA). In addition, the FFDF method enables a new high-fidelity validation technique for FEA utilising a precise full-field point by point similarity assessment with the experimental data, based on the fused data sets and metrics.ResultsIt is shown that inaccuracies introduced because of estimation of comparable locations in the data sets are eliminated, The FFDF also enables inaccuracies in the experimental data to be mutually assessed at the same scale regardless of differences in camera sensors. For example, the effect of processing parameters in DIC such as subset size and strain window can be assessed through similarity assessment with the TSA.ConclusionsThe FFDF methodology offers a means for comparing different design configurations and material choices for complex composite substructures, as well as quantitative validation of numerical models, which may ultimately reduce dependence on expensive and time-consuming full-scale tests.

Modal Analysis and Flow through Sectionalized Pipeline Gate Valve Using FEA and CFD Technique

Sectionalized gate valves can reduce the volume of product released in the event of a buried pipeline failure or rupture. The risk of pipeline failure is a constant and common occurrence, and many factors can lead to pipeline incidents. In this paper, the free undamped vibration of the pipeline, sectionalized gate valve structure, and the dynamics of the fluid passing through the system are investigated. First and foremost, a modal analysis based on finite element analysis (FEA) is introduced as a fundamental linear dynamics analysis to provide insight into how a pipeline sectionalized gate valve structure may respond to different types of dynamic loading. Secondly, an implicit numerical analysis using computational fluid dynamics (CFD) is employed to describe physical quantities such as the flow velocity profiles at different stream positions and pressure fields at different points in a control volume. Through modal analysis, the effective mass factor shows the mass involved in each mode and helps identify modes with high potential to cause damage and prioritize efforts to address them. The CFD suggests that the sectionalized design of the gate valve leads to a strong vorticity of the fluid in the transversal direction of the flow and a decrease in efficiency due to pressure drop.

Analysis of heat transfer characteristics of a sandwich cylindrical shell with a metal-rubber core

This work aims to analyze the heat transfer characteristics of a sandwich cylindrical shell with a metal-rubber core (SCS-MR) using both finite element analysis and experimental techniques. The SCS-MR is a lightweight and high-temperature resistant material that is suitable for construction in environments with varying conditions, such as rocket launchers, aircraft injectors and ships. The heat transfer, heat flux, and thermal convection loss were first analyzed using thermal resistance and Fourier law. Subsequently, a representative volume element of the SCS-MR was established to simulate thermal transfer, followed by a series of comparative experiments that measured the temperature gradients, the boundary conditions, and the density of the SCS-MR. Additionally, three types of metal spirals were examined using differential scanning calorimeter (DSC). The convective thermal conductivity, heat flux, and heat convection loss of the SCS-MR were analyzed experimentally, revealing that the metal spiral exhibited an exothermic peak in the DSC. Furthermore, the heat transfer rate of the SCS-MR was faster than that of the solid cylindrical shell (CS) when the set temperature was reached. The insulation cover was capable of providing boundary conditions to minimize the impact of natural convection. In the high-temperature environment, the thermal conductivity decreased with increasing density of the scaled model SCS-MR.

A novel physics-informed neural networks approach (PINN-MT) to solve mass transfer in plant cells during drying

Predicting microscale mechanisms of plant-based food materials has been an enduring challenge due to the inherent complexity of involved physics and prohibitively-high computational costs. As an alternative to conventional methods of solving corresponding Partial Differential Equations (PDEs), Physics-Informed Neural Networks (PINNs) have recently received significant attention from the research community. This article investigates the feasibility of PINNs' Automatic Differentiation (AD) to solve mass transfer (PINN-MT) and effectively predict cellular-level mass loss and subsequent moisture variations during low-temperature drying. PINN-MT has been developed by incorporating the residuals of convective mass transfer equation, Fick's law of diffusion and relevant initial conditions into the loss function. The integration of Adaptive Activation (AA) and Transfer Learning (TL) leads to improved computational efficiency, prediction accuracy and consistency. To the best of the authors' knowledge, this study is the first of its kind to apply PINNs' AD to solve mass transfer for food-drying. The PDE-solving capacity of the proposed approach has been compared with that of the state-of-the-art Finite Element Analysis (FEA) techniques. Compared to benchmark FEA results, percentage errors for PINN-MT-based mass loss and moisture distribution predictions remain below 0.23% and 0.33%, respectively. In addition, TL enhances the solution-based prediction efficiency of PINN-MT by more than 80%. Further, a novel approach has been proposed to achieve time-efficient predictions by feeding mass transfer coefficient-hm as an independent input to the proposed predictive framework, which has the potential to tackle complex and highly non-linear physics-based models, where conventional computational approaches usually struggle.

Finite element analysis of process parameters influences on deformation and von mises stress in drilling

Drilling is a very important machining process which accounts for more than 20% of the machining processes. Failure of drill bit is crucial when drilling difficult to machine materials such as composites and high temperature alloys. Selection of drill bit tool geometry, drill material and process parameters are vital for success of drilling difficult to machine materials. Finite element analysis and Taguchi Techniques are coupled to find out the optimum drilling parameters. Three process parameters such as material used for the drilling bit, cutting speed and drill point angle are used for analysis. Deformation and von mises stress are considered as response variables. The Taguchi method is employed to figure out the optimal process parameters for drilling operations. Based on SN ratio analysis and ANOVO, optimum drilling parameters for deformation were found to be CBN with 2000 rpm cutting speed and 114 as the drill point angle. From ANOVO analysis, it was found that drilling RPM is the most significant process parameter.

Mixed mode stress intensity factors of single edge cracked/notched plates under different boundary conditions using strain energy approach

This paper presents the mixed mode I/II stress intensity factors (SIFs) of slanted cracks/notches under tension loading. A two-dimensional finite element analysis (FEA) was employed using the ABAQUS program. Based on the literature survey, there is a lack of solutions for SIFs of slanted cracks in plane stress plates. The strain energy approach (SEA) was adopted to analyze the notched cases. Mode I and II SIFs are derived via the SEA method from the strain energy computed using the FEA technique. The results show excellent agreement with other researchers' work. The key contribution of the present paper is the presentation of the effect of the crack/notch length to plate width ratio on the mode I and II SIFs of a slant-edge-cracked/notched plate under different boundary conditions. Sets of new data of mode I and II SIFs are provided herein in tabular and graphical formats.

A Finite-element Method of Solution for Optimization of Frame of Tractor Operated Single Row Maize Cobs Picker

Finite element analysis (FEA) is a computational technique that divides complex structures into small elements and solves them numerically using various partial differential equations. In agriculture, engineers can use numerical simulation based on the FEA technique to study the behaviour of various input products in order to optimise the design of any machine without developing a prototype. The present study focused to design and simulates the frame of tractor operated single row maize cobs picker by employing the FEA technique. A 3D-CAD model of the frame of a tractor-operated single row maize cobs picker was created using the Solid Works software, and a static structural test was performed using the FEA technique in the ANSYS version 15.0 workbench software. A special fixture has been developed to calculate the force required to scrape the pulpy material of the leaves in the Universal Testing Machine. According to the simulation results, maximum deformation was observed as 0.051mm while maximum shear stress and Von Mises equivalent stress were found to be 0.246 MPaPa and 1. 47 MPa, respectively at 250 N scraping forces. Additionally, it was noted that the stress values fall within the material's yield strength. The FEA approach was found to be a scientific and highly effective method for designing and simulating the frame of a tractor-operated single row maize cobs picker.

Longitudinal seismic fragility assessment of an integral bridge-ground system in liquefaction-induced lateral spreads

Liquefied soils may induce widespread permanent ground deformation in the vicinity of abutments and cause extensive damage to bridge foundations during earthquakes. As such, it is essential to systematically assess the performance of bridges susceptible to earthquake hazards and associated soil liquefaction. Motivated by details of an actual 18-span bridge system, a three-dimensional (3D) nonlinear Finite Element (FE) framework is presented to quantify the damage exceedance probability conditioned on various earthquake intensity levels. An optimal intensity measure is identified by overall consideration of correlation, efficiency, and coefficient of variation to reduce the degree of uncertainty in the probabilistic seismic demand model, thus enhancing the confidence in the corresponding fragility results. To capture the salient mechanisms associated with soil liquefaction, this study focuses on the longitudinal seismic performance of bridge-ground as an integral system exposed to earthquake hazards. Within the developed 3D FE framework, the potential of geotechnical and structural mitigation measures is explored to reduce the vulnerability of the bridge structure. It is shown that the vulnerability of the bridge at some locations of interest is noticeably reduced by employing these measures. Overall, the 3D FE analysis technique and derived insights are of significance for the seismic response and fragility assessment of integral bridge-ground systems in liquefaction-induced lateral spreads.

Mechanics of vibrotactile sensors for applications in skin-interfaced haptic systems

Recent advances in haptic interfaces support a range of options in adding sensations of touch to virtual and augmented reality experiences. A fundamental understanding of the mechanics associated with coupling between vibro-tactile actuators and the skin is important in considering device designs and interpreting sensory perceptions. Here, we investigate vibrational dynamics induced by the three main classes of such actuators in bilayer elastomer structures that capture essential mechanical properties of human skin. The measurements rely on three dimensional digital image correlation methods, with corresponding simulations based on finite element analysis techniques. Studies examine the effects of key parameters relevant to the mechanics and resulting sensations, such as those related to contact area, actuation amplitude and spatio-temporal distributions of displacements in terms of both surface and body waves. Results reveal that tactor type actuators operate in a power efficient mode to produce deformations largely oriented out of the plane of the skin, for robust sensations that can, however, depend strongly on mounting strategy. Actuators based on eccentric rotating motors yield deformations with similar magnitudes but with substantial in-plane components and reduced sensations. Key attractive features of these actuators are in small, lightweight designs that facilitate mounting on the skin and deployment into large arrays. A third type of device, linear resonant actuators, produce the weakest sensations and the lowest power efficiencies, with limited potential for practical applications.

Review of Physical, Mechanical, and Biological Characteristics of 3D-Printed Bioceramic Scaffolds for Bone Tissue Engineering Applications.

This review focuses on the advancements in additive manufacturing techniques that are utilized for fabricating bioceramic scaffolds and their characterizations leading to bone tissue regeneration. Bioscaffolds are made by mimicking the human bone structure, material composition, and properties. Calcium phosphate apatite materials are the most commonly used scaffold materials as they closely resemble live bone in their inorganic composition. The functionally graded scaffolds are fabricated by utilizing the right choice of the 3D printing method and material combinations to achieve the requirement of the bioscaffold. To tailor the physical, mechanical, and biological properties of the scaffold, certain materials are reinforced, doped, or coated to incorporate the functionality. The biomechanical loading conditions that involve flexion, torsion, and tension exerted on the implanted scaffold are discussed. The finite element analysis (FEA) technique is used to investigate the mechanical property of the scaffold before fabrication. This helps in reducing the actual number of samples used for testing. The FEA simulated results and the experimental result are compared. This review also highlights some of the challenges associated while processing the scaffold such as shrinkage, mechanical instability, cytotoxicity, and printability. In the end, the new materials that are evolved for tissue engineering applications are compiled and discussed.

Response characteristic of crane-wharf interaction system: Numerical simulation and global sensitivity analysis

Crane, an important platform to carry and move cargo in the ports, can evidently affect the overall response of pile-supported wharf system. In many earlier analytical studies, the crane was simply represented by a lumped mass. Such modeling is unable to realistically replicate the salient response characteristics of crane-wharf interaction system. To investigate such interaction effects, a three-dimensional (3D) finite element (FE) model of a typical crane-wharf system is developed. As such, the static/dynamic response of pile-supported wharf with/without crane are systematically studied and directly compared. In addition, global sensitivity analysis is conducted to explore the effects of input parameter uncertainties on global response of crane-wharf system. From the computed results, it is shown that: (1) both the static and dynamic response are considerably dependent on the crane-wharf structure as an integral global system; (2) the bending moment and displacement of pile are more sensitive to the friction angle of soil stratum near pile tip; and (3) the interaction effect among various uncertainty parameters becomes more significant with consideration of crane. Overall, the 3D FE analysis technique and the derived insights provide a useful reference and guidance for evaluation of similar crane-wharf interaction system under static/dynamic loading conditions.