Commercial Finite Element Analysis Software Research Articles

Buckling of planar curved beams with finite prebuckling deformation

The serpentine structure with a sufficiently thick cross section has recently been proposed as an important design concept in stretchable electronics, which features mechanically stable in-plane deformation mechanism and very low electrical resistance, bringing unique advantages for devices compared with the traditional thin ribbon layout. However, unduly increasing the thickness is well known to sacrifice the overall flexibility and functionality of devices. Such a contradiction leads to challenges in structural stability, as a relatively thick but insufficient serpentine structure may eventually undergo the out-of-plane buckling after significant in-plane prebuckling deformation and appreciable alterations in initial configuration, which is ignored by most conventional buckling theories (CBTs) and linear buckling analysis in commercial finite element analysis software, producing intolerable errors when predicting the critical loads. In this paper, a systematic and straightforward theory considering the finite prebuckling deformation (FPD buckling theory) is established to investigate the underlying mechanism. Two sets of governing equations related to the prebuckling and FPD buckling behavior are obtained. Four representative examples, including two classical problems of planar curved beams and two typical loading conditions of serpentine structures, have been carefully studied. Comparisons with the accurate geometrically-nonlinear-analysis-based (GNAB) buckling analysis have amply demonstrated the validity of our theory in predicting the reinforcement effect of prebuckling deformation on the buckling resistance of structures. Key dimensionless geometric parameters that govern this effect have also been identified, providing direct and effective guidance for the design and optimization of stretchable electronic devices.

Design and Testing of Vehicle-Mounted Crop Growth Monitoring System

The aim of this study was to overcome the impact of vibration generated by agricultural machinery on the monitoring accuracy and performance of vehicle-mounted crop growth monitoring systems during field operation. This paper developed a vehicle-mounted crop growth monitoring system with vibration damping capability to achieve this goal. The system consists of a multispectral crop growth sensor, signal conditioning module, and truss-type sensor bracket with self-vibration damping capability. The commercial finite element analysis software ABAQUS 6.10 was used to conduct modal and dynamic simulation analyses of the sensor bracket, which indicate that the truss-type sensor bracket can damp vibrations effectively. The p-values (least significant differences) of crop canopy DNRE (red edge normalized difference vegetation index) under different operating speeds (1.5, 3, and 4.5 km/h) are 0.454, 0.703, 0.81, and 0.838, respectively, for four different crop growth stages. In a comparative experiment between the proposed monitoring system and two similar vehicle-mounted sensors (CropSpec and GreenSeeker RT 200) for measuring agronomic parameters at different stages of crop growth, the proposed monitoring system yielded R2 values of 0.8757, 0.7194, and 0.795, respectively, and RMSE values of 0.7157, 2.2341, and 2.0952, respectively, in the tillering stage, jointing stage, and tillering and jointing stage, outperforming the other two sensors.

Evaluation of borehole interface shear test simulations for cohesive soils under monotonic loading: A comparison of Mohr–Coulomb and hypoplasticity constitutive models

The Cyclic Interface Shear Test (CIST) device was recently developed to evaluate the response of soil–structure interfaces subjected to monotonic or cyclic loading. Numerical models of the CIST have not been documented. Such simulations may be beneficial to help guide the design of experiments, interpret results, and inform the development of further experimental device modifications. In the present paper, a series of interface shear tests utilizing the CIST system on a cohesive soil under monotonic loadings were simulated using a proposed three-dimensional model in the commercial finite element analysis software ABAQUS/Standard. Comparisons of simulations with experimental results are presented for the Mohr–Coulomb and hypoplasticity models for cohesive soils. It is found that (i) the clay-based hypoplasticity model outperformed the simpler Mohr–Coulomb model in terms of predicting the interface shear stress evolution and the soil volume change and (ii) the clay-based hypoplasticity model allows for identification of trends in shear response as a function of normal confining pressures at the soil–structure interface (e.g. soil–structure interface shear zone thickness). Neither of these capabilities have previously been documented or experimentally validated for cohesive soil–structure interface simulations using clay-based hypoplasticity models.

Carbonized hemp hurd powder for eco-friendly polybenzoxazine composite brake material: Excellent friction property and high mechanical performance

Non-asbestos and non-copper polybenzoxazine friction composites were developed with varying mass ratios of synthetic graphite (SG)/carbonized hemp hurd (CHH). Mechanical, thermal, and tribological properties of the polybenzoxazine friction composites were studied. The wear simulation of the polybenzoxazine friction composites has been performed with commercial ANSYS finite element analysis software. The strength and modulus under flexure mode, glass transition temperature of the polybenzoxazine friction composite samples were observed to be improved with increasing CHH content. It appears that the incorporation of the CHH into the polybenzoxazine friction composites not only enhanced the coefficient of friction (COF) but also improved the overall wear resistance of the units. The wear resistance and wear pattern obtained by the wear simulation also showed a good correlation with the experimental results. Based on the findings in this study, it is evident that the carbonized hemp hurd possesses a great potential to be used in green brake pad application.

A Study on the Residual Stress of Seam Pipe Cutting and Girth Welding

Seam pipes are easier to manufacture and cheaper than seamless pipes, and are widely used in the manufacture of pipe spools for marine plant facilities. The manufacturing and assembly of seam pipes involve welding and cutting. The localized heating and cooling that occur during these processes may change the existing residual stress and cause deformation. Uncontrolled deformation can accumulate as assembly errors at the next step, potentially delaying the entire process and causing economic losses. Therefore, characteristics of residual stress redistribution caused by cutting and girth welding of seam pipes need to be studied further. In this study, we performed thermo-mechanical analysis of the manufacturing, cutting, and girth welding processes of seam pipes using the commercial finite element analysis (FEA) software MSC Marc and analyzed the characteristics of residual stress. Furthermore, we measured the residual stress in each process using the hole drilling method, analyzed the characteristics of redistributed residual stress, and ensured reliability. Based on the results of FEA and measured residual stress redistribution, we can provide a basis for reasonable mitigation when performing structural integrity evaluation if there is a defect in the weld of the pipe.

User subroutines platform development for rubber hyperelastic constitutive models and its application in finite element analysis

Aiming at the problem that not enough hyperelastic constitutive models (HCMs) built-in commercial finite element analysis (FEA) software could be utilized, and it is difficult to achieve a high-precision description of the mechanical response behavior of various complex rubber and its composite materials, we developed a UHYPER and UMAT subroutine integration platform based on the user-defined material subroutine function in Abaqus/Standard. The integration platform including 70 HCMs can effectively improve the selection comprehensiveness of HCMs in the material property module of FEA software and the accuracy of simulation results. On the premise that the material parameters are consistent, it is found that the calculation results of the UHYPER subroutine in our integration platform are completely consistent with the calculation results of the built-in HCMs in Abaqus, and the error between the UMAT subroutine result and the built-in model result is within 5.0%. This study indicates the effectiveness and reliability of the user-defined material subroutine integration platform.

Strategies for Reducing Booming Noise Generated by the Tailgate of an Electric Sport Utility Vehicle

This article investigates the source of booming noise emanating from the tailgate of an electric sport utility vehicle (SUV), along with proposed strategies to mitigate it. This annoying low-frequency booming noise, which significantly impacts interior sound quality, is less perceptible in conventional internal combustion engine vehicles. However, this noise is more readily detected in electric SUVs, highlighting the necessity for focused measures to reduce it. This study involved the measurement of booming noises during on-road vehicle tests to pinpoint their origins. Additionally, ODSs were extracted from the tailgate vibration signals to gain insight into its dynamic behavior. Modal tests were conducted on the tailgate to determine its dynamic characteristics and compared with driving test results to reveal the mechanism responsible for tailgate-induced booming noise. It was established that such noise is primarily due to the tailgate modes, resulting from a combination of rigid body motion in the fore-aft direction and deformation in the central section of the panel. An analytical model of the tailgate was developed using commercial finite-element analysis software to propose measures for reducing booming noise. Experimental findings validated this model’s accuracy. Structural enhancements were implemented to enhance the panel stiffness and improve the connection between the vehicle and tailgate via bushings to reduce the booming noise resulting from tailgate motion. Under random force inputs, the analytical results demonstrated a 13.8% reduction in maximum deformation in the tailgate model in the improved structural configuration with increased panel stiffness. This study identifies the mechanism generating booming noise, establishes a practical and simple dynamic model, and proposes improvement measures aimed at reducing the booming noise.

Finite Element Method in L-PBF of Ti-6Al-4V: Influence of Laser Power and Scan Speed on Residual Stress and Part Distortion

Laser powder bed fusion (L-PBF) is widely used in automotive, aerospace, and biomedical applications thanks to its ability to produce complex geometries. In spite of its advantages, parts produced with this technology can show distortion due to the residual stresses developed during the printing process. For this reason, numerical simulations can be used to predict thermal gradients and residual stresses that can result in part distortion. Thus, instead of performing experimental tests and using a trial and error approach, it is possible to use numerical simulation to save time and material. In this work, the effect of laser power and scan speed on residual stress and part distortion was analysed using a commercial finite element analysis (FEA) software DEFORM-3D™ with a layer-by-layer approach. Moreover, the accuracy of the numerical model with respect to process parameters and the utilised mesh was also studied. The results obtained from the numerical simulation were compared to the actual distortions to evaluate the accuracy of the FEM model. The predicted distortions using FEM analysis well fit the trend of the measured ones. The accuracy of the numerical model increases by considering a finer mesh.

Investigation of the influence of sinusoidal internal waves on a SPAR buoy structure

Offshore wind has a great potential as a competitive source of renewable energy, especially in deep waters where wind speeds are more consistent and fewer restrictions apply for running large wind turbines. Previous analyses of Floating Offshore Wind Turbines (FOWTs) mostly considered obvious sources of loading: surface waves, currents, wind and mooring. However, in some deep-water locations, internal waves can occur and these have been shown to significantly affect floating structures. Since the hydrodynamic response of an FOWT governs the structure’s general stability, the aim of this research is to investigate the impact of sinusoidal internal waves on the platform motion of a free-floating SPAR-type cylinder. A potential flow model and Morison’s equation are applied numerically to calculate the forces acting on a free-floating cylinder in an oscillating flow. The commercial Finite Element Analysis software OrcaFlex is verified by the potential flow model of the oscillating flow and is then used to mimic sinusoidal internal waves acting on a free-floating cylinder in a stratified flow. Three different internal wave amplitudes and peak velocities are analysed, and the nine resulting cases are investigated for the oscillating and stratified flow each. It has been found that the pitch rotations of the SPAR cylinder were small (< 0.1°) in all cases and can likely be disregarded. The surge displacements of the free-floating cylinder were substantial in both oscillating and stratified flows, with maximum surge magnitudes of 423m and 120m, respectively. Therefore, significant additional mooring loads due to internal waves could be sustained by SPAR-type FOWTs.

Development of a Treatment Planning Framework for Laser Interstitial Thermal Therapy (LITT).

Develop a treatment planning framework for neurosurgeons treating high-grade gliomas with LITT to minimize the learning curve and improve tumor thermal dose coverage. Deidentified patient images were segmented using the image segmentation software Materialize MIMICS©. Segmented images were imported into the commercial finite element analysis (FEA) software COMSOL Multiphysics© to perform bioheat transfer simulations. The laser probe was modeled as a cylindrical object with radius 0.7 mm and length 100 mm, with a constant beam diameter. A modeled laser probe was placed in the tumor in accordance with patient specific patient magnetic resonance temperature imaging (MRTi) data. The laser energy was modeled as a deposited beam heat source in the FEA software. Penne's bioheat equation was used to model heat transfer in brain tissue. The cerebrospinal fluid (CSF) was modeled as a solid with convectively enhanced conductivity to capture heat sink effects. In this study, thermal damage-dependent blood perfusion was assessed. Pulsed laser heating was modeled based on patient treatment logs. The stationary heat source and pullback heat source techniques were modeled to compare the calculated tissue damage. The developed bioheat transfer model was compared to MRTi data obtained from a laser log during LITT procedures. The application builder module in COMSOL Multiphysics© was utilized to create a Graphical User Interface (GUI) for the treatment planning framework. Simulations predicted increased thermal damage (10-15%) in the tumor for the pullback heat source approach compared with the stationary heat source. The model-predicted temperature profiles followed trends similar to those of the MRTi data. Simulations predicted partial tissue ablation in tumors proximal to the CSF ventricle. A mobile platform-based GUI for bioheat transfer simulation was developed to aid neurosurgeons in conveniently varying the simulation parameters according to a patient-specific treatment plan. The convective effects of the CSF should be modeled with heat sink effects for accurate LITT treatment planning.

An experimentally validated anisotropic visco-hyperelastic constitutive model for knitted fabric-reinforced elastomer composites

A new anisotropic visco-hyperelastic constitutive model has been developed to predict the time-dependent deformation response of flexible, knitted fabric-reinforced elastomer composites. These composites exhibit a time-dependent response due to the viscoelastic behavior of the elastomer, while the anisotropic reinforcement effect is attributed to the knitted fabrics. The proposed modeling approach features an invariant-based strain energy density function that incorporates the architecture of knitted fabrics and the hyper-viscoelastic behavior of elastomers. In this study, the elastomer is considered as a viscous neo-Hookean material, and the knitted fabrics are modeled as cords with negligible stiffness in bending. The proposed material model is implemented in commercial Finite Element Analysis (FEA) software, Abaqus (version 2017), through a user-defined material subroutine, UMAT. This approach enables the determination of the constitutive behavior of the composite based on the constituent elastomer, fiber properties, and fabric architectures. The proposed model is verified through a discrete 3D FEA model, in which the elastomer and fabric reinforcement are modeled explicitly. The approach is further validated through physical testing including uniaxial tension, torsion, and three-point bending. Since the proposed strain energy-based constitutive model can predict the deformation response of knitted fabric-reinforced elastomer composites based on the fabric architecture, it can be employed as an efficient modeling tool to aid the design of knitting pattern for target mechanical properties.

Structural Reliability Analysis of Large Planar Steam Solid Oxide Electrolysis Cells

Solid oxide electrolysis cells (SOEC) have been receiving significant attention recently because of their high energy efficiency and fast hydrogen production. In our previous study, a multi-physics modeling framework to simulate the SOEC performance and structural reliability of planar SOEC design was developed and demonstrated. The electrochemical reactions, fluid dynamics, species transport, electron transfer, and heat transfer were modeled in the commercial computational fluid dynamics (CFD) software STAR-CCM+. The thermomechanical analysis and the associated structural reliability evaluations were conducted using the commercial finite element analysis software ANSYS. The electrochemistry model was validated by using the experimentally obtained current-voltage (I-V) characteristics of the electrode-supported SOECs. In this study, this framework was applied on a large 300 cm2 steam planar SOEC design, and systematically studied the structural reliability under combinations of cell operating conditions, with cell voltage 1-1.5 V, steam fraction in fuel inlet 0.7-0.9, air inlet flow rate 0-10 L/min, fuel inlet flow rate 2.5-12.5 L/min, and inlet temperature 600-900 C. In the modeling framework, all the cells were investigated under the adiabatic thermal conditions, which is equivalent to packing the cell in an insulated container. This induced the relatively larger temperature variation than in the smaller cell designs. This cell internal temperature non-uniformity may further enhance the spatial variations of open circuit voltage, activation loss, and ionic conductivity in the cell, which all influence the overall cell performance. This situation is more obvious when the cell voltage is higher than 1.35V, under which the cell is significantly heated along the steam flow direction. Traditionally, it is assumed that the cell internal temperature spatial variation plays an important role on cell structural reliability. However, because it was assumed that all the components in cell are stress free at 850 , the cell temperature deviation from 850 is more critical to the stress distribution and structural reliability in the cell. For the investigated cells in the practical conditions, like 750 C inlet temperature and varying voltage from 1.05 to 1.5 V, the highest first principal stress is always in the air side electrode, which is around 45 MPa. This is explained by the higher coefficient of thermal expansion of LSCF-GDC with respect to the other layers. This may indicate that the failure would possibly occur in the air side electrode, but at low risk due to the relatively higher Weibull characteristic strength.

Progressive Failure Analysis of Composite Overwrapped Pressure Vessel

Stress and progressive failure analysis (First Ply Failure to Last Ply Failure) of a composite overwrapped pressure vessel (COPV) with an aluminum liner using the finite element method (FEM) in general and commercial finite element analysis (FEA) software ANSYS in particular is presented in this paper. Ply failure prediction is based on failure criteria implemented in ANSYS software. The first-ply failure (FPF) does not necessarily imply the total failure of a laminate. After FPF, the laminate stiffness is reduced consistent with identified ply failure mode. The strength of the composite laminate is evaluated again to see if it could carry additional load. This ply-by-ply analysis progresses, until the ultimate strength is reached. In the present study the methodology is validated using benchmarks and applied to a filament wound fibre reinforced plastic composite pressure vessel with an aluminum liner. Significant results are presented and critically assessed. Directions for further work in this field are identified.

The transformation matrix in the 7DOFs beam formulation

A non-negligible percentage of steel products for civil and industrial constructions is realised with members characterised by a mono-symmetric cross-section. The non-coincidence between the centroid and the shear centre reflects in a quite complex behaviour that is remarkably influenced by the warping effects. Usually, frame design is based on the output data of commercial Finite Element Analysis Packages (FEAPs) but only few of them offer a refined beam element formulation able to reproduce the response of non-bisymmetric cross-section members (like the 7 degrees of freedom, DOFs, beam element). As a consequence, warping effects are usually neglected in routine design, leading in several cases to assess non-correct internal stresses, global displacements and critical buckling multipliers.This paper is focussed on mono-symmetric cross-section members and deals with the influence of the interaction between axial force, bending moments and bimoment in linear elastic range. In particular, the two strategies that FE developers usually adopt, in the 7 DOFs beam formulation, to pass from the local to the global reference system are herein shortly introduced and discussed. The effects of the associated transformation matrices have been investigated in few examples, also reproduced via closed expressions derived from the mixed torsion theory and FE shell models. Paper outcomes show that the results in terms of generalised displacements, internal forces and, consequently, stress distribution along the member cross-section are significantly different, strictly depending on the adopted transformation matrix. The importance of a correct evaluation of the bimoment distribution is stressed also by the fact that the new edition of the EN1993-1-1, expected in the next months, includes also the bimoment contribution for member checks.

A simplified finite element method for failure analysis in adhesive-bonded nozzle diffuser of solid rocket motors

The adhesive bond between the nozzle diffuser shell and the insulation layer of solid rocket motors (SRM) is widely used due to its lightweight, simple design, and easy operation. The mechanism of adhesive-bonded failure between them is a concern for designers. In this paper, a simplified finite element method for failure analysis in the adhesive-bonded nozzle diffuser of SRM is proposed. In the method, the diffuser shell, insulation layer, and adhesive between them are considered elastic. The maximum Von Mises stress failure criterion is assumed to be suitable for the adhesive. The adhesive-bonded failure is simulated by using the user subroutine VUSDFLD in the commercial Finite Element Analysis software ABAQUS. The method is verified to be simple but effective based on the comparison with experimental results. The adhesive-bonded failure process under external load can be well simulated, and the critical external load of adhesive-bonded failure can be accurately predicted. In addition, the method is utilized to study the failure of the nozzle diffuser with several kinds of original debonding. It is suggested that the original axial debonding ratio should be less than 60%, and the circumferential debonding angle should be smaller than 30° in the conical section of the nozzle diffuser.

A study of a slim compact piezo inertia actuator

Most previously reported inertia actuators suffer from the problems of low speed and large size. To overcome these shortcomings, this study proposes a slim compact piezo inertia actuator based on the principle of stick–slip drive. Actuated by the transverse motion of a cantilever beam forming part of a monolithic elastomer, this actuator achieves a high velocity. The construction and basic operating principle of the actuator are discussed in detail. Commercial finite element analysis software is employed to determine the appropriate geometry for the monolithic elastomer. To study the actuator’s mechanical characteristics, a prototype is fabricated and a series of experimental tests are performed. According to the results of these tests, the maximum velocity and maximum load force are about 24.03 mm/s and 1.96 N, respectively, and the minimum step size is about 0.47 μm. It is shown that the inertia actuator based on a monolithic elastomer with a cantilever beam not only has a slim compact structure, but also exhibits good output characteristics.

Experimental and numerical investigation on enhancing capped-end tube energy absorption capacity by orifice effect

This work proposes a method of energy absorption via phase change material (PCM)-filled circular tubes with caps and orifices on their end surfaces. As a novel method of energy absorption, energy absorbers were filled with a squeezable material. These filled tubes were anticipated to offer superior energy absorption performance than hollow tube systems thanks to energy dissipation during material squeezing through orifices. It has been experimentally studied how these tubes react when crushed by quasi-static lateral force. We used a hemi-cylindrical indenter to laterally compress the samples. Using systematic case design (SCD) and finite element (FE) method, we were able to provide guidelines for the effect of geometrical parameters of filled tubes to be employed as energy absorbers under lateral compression. Commercial FE analysis software (LS-Dyna) was used to develop the FE model, which was then validated by experimental results. Specific energy absorption capacity (SE) and force-displacement curves of filled tubes were derived as a function of geometrical parameters including thickness, diameter, and orifice size. A parametric studywas conducted to evaluate the principal and interactive effects of geometrical factors on the SE. In conclusion, we proposed an empirical formulation of energy absorption as a function of geometrical factors for a PCM-filled capped-end tube that can predict energy absorption with more than 95% accuracy. Validation was further achieved by comparison with analytical method.

Temperature Field Analysis of Novel Die Bonding Stage for MEMS Thermopile

Packaging and die bonding of conventional micro‐electro‐mechanical‐systems (MEMS) and semiconductor devices include separate dispensing, mounting and heating curing. A novel die bonder's work stage and temperature control method are proposed so that dispensing, mounting and heating curing can be completed at the same station. This paper introduces the working principle of the thermopile sensor and the requirements for temperature change during die bonding, analyses the main structure and working process of the novel die bonding stage, and uses commercial finite element analysis software to evaluate the temperature field of the novel die bonding stage and devices during the process of heating, holding and cooling to provide process guidance for accurate temperature control of die bonding. Dispensing, mounting and heating curing are integrated in the same station, avoiding the position error of devices when transferring, reducing the number of equipment and floor area, and effectively saving production costs. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Pulsed Eddy Current Sensor for Cascade Electrical Conductivity and Thickness Estimation in Nonferrous Metal Plates

This paper presents a pulsed eddy current (PEC) sensor design for cascade electrical conductivity and thickness estimation in non-ferrous metal plates. With a single excitation coil design, the combined change in magnetic flux density caused by the excitation coil and the induced eddy current (EC) in the test plate is detected by a compact anisotropic magneto-resistive (AMR) sensor. The effects of the varying input pulse width are discussed with both numerical simulations in commercial finite element analysis (FEA) software and experimental results, and the time-domain characteristics of the responses are analyzed in relation to the properties of the test plates. It is revealed that the electrical conductivity can be gauged based on the peak value of the short pulse response, and with a known electrical conductivity value, plate thickness can be subsequently derived with the rise time of the long pulse response. A cascade estimation process is therefore proposed to calculate the parameters sequentially by adopting hybrid input signals with both short and long input pulses. Verified by the FEA results, this cascade estimation process was then experimentally validated with a prototype of the PEC sensor.

A Cartesian spatial discretization method for nonlinear dynamic modeling and vibration analysis of tensegrity structures

For vibration analysis of a tensegrity structure, the development of a dynamic model is a key step. A common issue in the traditional dynamic modeling methods for vibration analysis of tensegrity structures is that structural members are oversimplified. Member internal displacements, including those in longitudinal directions for bar and cable members and those in transverse directions for cable members, were neglected. This oversimplification would inevitably prevent the dynamic model of a tensegrity structure so developed from revealing accurate responses, especially for those in the high-frequency domain. To resolve this issue, a new method called the Cartesian spatial discretization method is developed for nonlinear dynamic modeling and vibration analysis of tensegrity structures. This method can successfully incorporate member internal displacements in dynamic modeling of a tensegrity structure by defining positions of structural members as a summation of internal terms and boundary-induced terms in a global Cartesian coordinate system. The proposed method is applied to vibration analysis of a planar Snelson’s X tensegrity structure, a three-dimensional tensegrity tower, and an irregular tensegrity grid in simulation, and compared with the Lagrangian method based on generalized coordinates, the commercial finite element analysis software ANSYS and the finite element analysis method in literatures, respectively. Results show that the proposed method is accurate in predicting dynamic responses of tensegrity structures, especially for vibration analysis in the high-frequency domain. It is also demonstrated that the proposed method is applicable to both simple and complex tensegrity structures, and computationally efficient as it converges in a super-linear rate by using only a small number of internal terms of member displacements.