Finite Element Analysis Research Articles

Improvement of bionic surface of thrust rod ball joint and finite element analysis

The thrust rod is an important component of heavy-duty vehicles. It can transmit force and torque during vehicle driving and play the role of flexible connection. This paper mainly applies the bionic friction-increasing principle of locust foot pads to the rubber surface of the thrust rod ball joint of commercial vehicles. A bionic ball crown-shaped flexible protrusion is constructed on the surface of the rubber ball joint to increase the stiffness of the ball joint. The height, radius and spacing of the bionic flexible protrusion are changed, and the finite element analysis is performed using Abaqus software to study the radial stiffness, deflection stiffness and torsional stiffness of the thrust rod ball joint. The results show that the best effect is achieved when the protrusion height is 1 mm, the radius is 4 mm and the spacing is 10 mm. Finally, the optimal solution is comprehensively analyzed, and the feasibility of the solution is verified through simulation and experiment.

Mechanical analysis of polyester resin using digital image correlation and finite element method

The primary objective of this study is to perform a comprehensive mechanical analysis of unsaturated polyester (UP) resin under unidirectional tensile loading. The Digital Image Correlation (DIC) technique was employed to accurately determine the mechanical properties of the material, with full-field strain measurements used to extract both transverse and longitudinal strains through virtual extensometers. This approach facilitated the precise calculation of the Poisson’s ratio of the UP resin. The results obtained via DIC demonstrated strong correlation with the experimental data obtained through the machine’s control software, particularly in capturing vertical displacement and longitudinal strain with high precision. The Poisson’s ratio was found to be 0.46. To further validate the DIC findings, Finite Element Analysis (FEA) was conducted. The FEA results aligned closely with the experimental data, confirming the reliability and accuracy of the DIC method in this context. The values of Young’s modulus determined from experimental tests and FEA data were 3620.02 MPa and 3598 MPa, respectively, with a percentage error of only 0.61%.

Validation of patient-specific flatfoot models on finite element analysis

Adult-acquired flatfoot causes various deformities. If a patient-specific foot model can be created using the finite element method, it can be used to study the appropriate surgical technique for each patient. Nine patient-specific flatfoot models were created, and loading simulations were performed. To validate the models, the patients’ weight-bearing radiographs were compared with the parameters of the models. The CCC values ranged from 0.917 to 0.993 , all exceeding the moderate threshold according to the McBride criteria. Our model reproduces the biomechanics of a patient’s foot under loading conditions, which may be useful for investigating patient-specific surgical procedures.

Impact of bolt positioning on the stiffness of angular support brackets

Bolts and screws are usually preferred over other joining techniques when assembly and disassembly operations are required. However, they add extra weight to the system, so it is essential to reduce their size and weight by optimizing bolt parameters. Additionally, the stiffness of bolted members is very crucial; those with low stiffness may affect the correct functioning of the other connected components. This study focuses on the impact produced by bolt positions, specifically their center of gravity and spacing among them, on the stiffness of angular L-shaped brackets using Finite Element Analysis. Bending and torsional loads were applied to the free end of the member and deformations were recorded under these loads. The results revealed that a triangular bolt pattern is recommended for three bolts, whereas for four or more bolts, the pattern should be uniform to avoid stress concentrations. Moreover, the center of gravity and bolt spacing have a significant impact on stiffness. By optimizing bolt spacing and the center of gravity, a combination of six bolts can be replaced with four bolts of the same size while maintaining the same stiffness.

Design strategy for the prototyping of 3D-printed continuous fiber-reinforced components for solar-powered vehicle

Continuous fiber fused filament fabrication is an advanced 3D printing method that allows designers to produce high-performing lightweight structures, leading toward innovative design philosophies and sustainable production chains. In this work, we proposed a design strategy to manufacture selected components for a solar-powered vehicle, which consists of three stages. Firstly, the prototypes’ CAD models are developed, considering their geometric and manufacturing requirements. Then, a finite element analysis is carried out to ensure optimal fiber reinforcement of prototypes’ critical regions. Lastly, the manufacturing stage involves the slicing process and optimization of the time and cost of the printed part employing Markforged® technology. Adopting the proposed methodology, the experimental campaign investigated the print quality and performance of several prototypes of each component by adjusting printing parameters.

Prediction of bone ingrowth into a porous novel hip-stem: A finite element analysis integrated with mechanoregulatory algorithm.

Bone ingrowth into a porous implant is necessary for its long-term fixation. Although attempts have been made to quantify the peri-implant bone growth using finite element (FE) analysis integrated with mechanoregulatory algorithms, bone ingrowth into a porous cellular hip stem has scarcely been investigated. Using a three-dimensional (3D) FE model and mechanobiology-based numerical framework, the objective of this study was to predict the spatial distribution of evolutionary bone ingrowth into an uncemented novel porous hip stem proposed earlier by the authors. A CT-based FE macromodel of the implant-bone structure was developed. The bone material properties were assigned based on CT grey value. Peak musculoskeletal loading conditions, corresponding to level walking and stair climbing, were applied. The geometry of the implant-bone macromodel was divided into multiple submodels. A suitable mapping framework was used to transfer maximum nodal displacements from the FE macromodel to the cut boundaries of the FE submodels. CT grey value-based bone materials properties were assigned to the submodels. Thereafter, the submodels were solved and simulations of bone ingrowth were carried out using mechanoregulatory principle. A gradual increase in the average Young's modulus, from 1200 to 1500 MPa, of the bone tissue layer was observed considering all the submodels. The distal submodel exhibited 82% of bone ingrowth, whereas the proximal submodel experienced 65% bone ingrowth. Equilibrium in the bone ingrowth process was achieved in 7 weeks postoperatively, with a notable amount of bone ingrowth that should lead to biological fixation of the novel hip stem.

Enhanced elastic stress solutions for junctions in various pipe bends under internal pressure and combined loading ([formula omitted] pipe bend, U-bend, double-bend pipe)

Piping systems in nuclear power plants normally operate under high pressure and high temperature. To efficiently manage space within these systems, pipe bends are extensively used. However, the welded joints connecting these pipes may be susceptible to flaws due to weld residual stress, transient loads, and operating environments. When flaws are present in such areas, analytical evaluation of flaws is to be carried out based on fracture mechanics parameters such as stress intensity factor. To calculate the stress intensity factor, distributions of the elastic stress are required. Therefore, this paper presents closed-form approximations of elastic stress in the junction between a pipe bend and a straight pipe under internal pressure. Review of the existing elastic stress solutions for estimating the stresses in pipe bends was carried out analyzing their limitations. Based on those limitations elastic stress solutions for thick to thin wall pipe bends were proposed and were validated against finite element (FE) analysis for thick-wall to thin-wall pipe bends under internal pressure and combined loading (i.e. internal pressure, in-plane bending, out-of-plane bending inflicted simultaneously). 90° pipe bend, U-bend and double-bend pipe configurations were considered and showed good agreement with the FE results exhibiting less than 5.8 % discrepancies. The accuracy of the elastic stress solutions for pipe bends provided in the existing code are summarized and validated in the appendix as well.

Aspect ratio optimization of piezoelectric extensional mode resonators for quality factor and phase noise performance enhancement

Abstract This study focuses on optimizing the resonator geometry via the aspect ratio design of a width-extensional mode resonator to improve its quality factor (Q), which is one of the critical performance parameters for resonators in either sensing (Allan deviation) or frequency reference (phase noise) applications. The proposed approach uses finite element analysis to reduce the strain energy at anchor supports by altering the resonator geometric structure, thereby reducing energy loss through anchors. Moreover, process limitations on feature sizes are used as constraints to find aspect ratios that can not only increase the Q but also reduce spurious modes near the targeted frequency. The devices were fabricated using AlN thin film piezoelectric on a substrate (TPoS) process. The simulated energy dissipation trends for specific length-to-width (L/W) ratios closely match the measured changes in the resonator Q values in vacuum. In vacuum, the highest Q-factor achieved by the device is close to 8816, with a motional resistance of a few tens of ohms. Additionally, a board-level oscillator realized using a commercial low-noise amplifier exhibits phase noise performance of −141.21 dBc Hz−1 and −164.25 dBc Hz−1 at 1 kHz and 1 MHz frequency offsets, respectively. The calculated figures of merit for these offsets are 204 and 168, respectively.

Numerical investigation of thermal influence on debonding behavior in composite structures through a friction and cohesive coupled model

AbstractThis study conducts an in-depth numerical analysis of debonding behavior in composite structures, with a particular focus on the critical role of thermal effects. Utilizing a frictional contact cohesive zone model, the research characterizes the debonding process while sequentially integrating thermal analysis to assess the impact of thermal loading. A thermomechanical coupled model is developed and implemented using the finite element software ABAQUS. The model's accuracy is validated through the Double Cantilever Beam (DCB) test, ensuring reliable results. The methodology involves a detailed finite element analysis, where thermal loads are applied to composite specimens, followed by mechanical loading to simulate debonding. The frictional contact cohesive zone model accurately captures the interface behavior under varying thermal conditions. Quantitative results indicate that thermal loading significantly affects the debonding process, with a noticeable increase in debonding initiation and propagation rates, highlighting the critical influence of thermal effects on structural integrity.

Study on the folding damage mechanism of SiC fiber braided fabric based on synchrotron radiation CT and finite-element analysis

Silicon carbide (SiC) fiber exhibits high strength, thermal resistance, and chemical stability, but its insufficient flexural strength renders it unsuitable for use in flexible structural materials. In this study, the microstructure evolution and damage mechanisms of SiC fiber braided fabric were investigated at different braiding angles and folding stages using synchrotron micro computed tomography (µ-CT) and finite-element analysis. Results from synchrotron radiation CT scans indicate that, with an increase in the number of folding cycles, both fiber surface fractures and slippage gradually increased, leading to a looser internal structure and diminished fiber continuity. The SiC fiber braided fabric at 37.8° was predominantly influenced by the folding behavior, exhibiting a higher frequency of fiber breakages. Conversely, the 43.1° SiC fiber braided fabric was primarily affected by inter-bundle abrasion, resulting in looser fiber bundles and increased slippage. In the case of the 41.2° SiC fiber braided fabric, under the combined effects of friction and folding, the highest occurrences of fiber slippage and breakages were observed. Finite-element simulation results reveal that the stress at the folding site of the 40° braided fabric was higher than those of the 45° and 50° braided fabrics, confirming the experimental conclusion that the folding resistance of SiC fiber fabrics is poorest at a braiding angle of around 41° to 42°. This research is of significant importance for a deeper understanding of the folding performance and damage behavior of SiC fiber braided fabric, providing valuable insights for further optimizing material design and applications.

Automated detection of deformation mechanisms in re-entrant honeycomb auxetics using machine learning

The intricate geometrical configuration of an auxetic structure enables high energy dissipation capacity at the expense of a highly nonlinear mechanical response. Under external stimuli, complicated deformation mechanisms emerge which dictate the extent of energy dissipation. Recently, the new ‘plastic hinge tracing’ method (Dhari et al., 2021) was introduced to detect such deformation mechanisms for elastoplastic porous materials. This approach is however subjective and cumbersome since it requires monitoring several plastic regions in consecutive deformed configurations. The present study innovatively extends this method by implementing machine learning (ML) techniques for objective detection of deformation modes in auxetics. To this end, a logistic regression ML model was developed to classify the deformation modes of a re-entrant honeycomb structure. The proposed procedure could successfully detect four out of the six deformation modes (‘X’, distorted ‘X’, ‘V’, and ‘V + Z + V’) using the training datasets generated by the finite element analysis and image labels created by K-means clustering algorithm. The success of the proposed automated approach lays the foundation for identifying the deformation mechanisms of other auxetics and porous materials with plastic deformations.

A Novel Caterpillar-Inspired Vascular Interventional Robot Navigated by Magnetic Sinusoidal Mechanism

Magnetic soft continuum robots (MSCRs) hold significant potential in fulfilling the requirements of vascular interventional robots, enabling safe access to difficult-to-reach areas with enhanced active maneuverability, shape morphing capabilities, and stiffness variability. Their primary advantage lies in their tether-less actuation mechanism that can safely adapt to complex vessel structures. Existing commercial MSCRs primarily employ a magnetic-pull strategy, which suffers from insufficient driving force and a single actuation strategy, limiting their clinical applicability. Inspired by the inchworm crawling locomotion gait, we herein present a novel MSCR that integrates a magnetic sinusoidal actuation mechanism with adjustable frequency and kirigami structures. The developed MSCRs consist of two permanent magnets connected by a micro-spring, which is coated with a silicone membrane featuring a specific notch array. This design enables bio-inspired crawling with controllable velocity and active maneuverability. An analytical model of the magnetic torque and finite element analysis (FEA) simulations of the MSCRs has been constructed. Additionally, the prototype has been validated through two-dimensional in-vitro tracking experiments with actuation frequencies ranging from 1 to 10 Hz. Its stride efficiency has also been verified in a three-dimensional (3D) coronary artery phantom. Diametrically magnetized spherical chain tip enhances active steerability. Kirigami skin is coated over the novel guidewire and catheter, not only providing proximal anchorage for improved stride efficiency but also serving similar function as a cutting balloon. Under the actuation of an external magnetic field, the proposed MSCRs demonstrate the ability to traverse bifurcations and tortuous paths, indicating their potential for dexterous flexibility in pathological vessels.

Versatile Standing Wave Generation Between Arbitrarily Oriented Surfaces Using Acoustic Metasurface Deflectors and Retroreflectors

Acoustic wave devices using standing wave configurations have gained interest in various fields like healthcare diagnostics and manufacturing. Their functionalities span from cell sorting to microscale fiber assembly through periodic acoustic pressure fields. Conventional methods usually require parallel acoustic emitters and reflective surfaces, producing constrained standing wave patterns. In this paper, an effective approach for creating versatile acoustic standing wave fields using an acoustic metasurface deflector and retroreflector is introduced. The deflector manipulates the direction of incoming acoustic waves coupled with the retroreflector to reflect these waves back to the source. The proposed design allows the creation of standing waves that are not constrained by the relative angles of the two surfaces involved and allows for customizable wave patterns beyond the standard limits with enhanced adaptability. The system's effectiveness is evaluated through computational simulations using finite element analysis and experimental validation based on a 3D‐printed prototype. Results suggest that versatile standing waves between arbitrarily oriented surfaces can be produced through the careful design of the metasurface deflector and retroreflector. This approach can improve the performance of standing wave applications in particle manipulation, thus broadening the range of practical implementations for ultrasound and acoustofluidic technologies.

A Gaussian statistics-based unit-cell modeling method for the mechanical behavior prediction of 2.5D shallow straight-link-shaped woven composites

The shallow straight-link-shaped structure of 2.5D woven composites (2.5D-SSLS-WC) is a novel material with a wide range of promising applications, but the randomness of its internal structure has brought challenges to performance prediction and engineering design. The gap of existing unit-cell models in capturing the internal randomness of the 2.5D-SSLS-WC material limits the accurate prediction of properties and the optimization of engineering design. In this work, the modeling method for random unit-cell model based on Gaussian distribution is proposed for 2.5D-SSLS-WC structure considering random distribution property of weft yarns and extrusion effects between structural surfaces and internal yarns during the molding process, which can more effectively reflect the practical mesoscopic structure of the material, reveal the micro mechanical behavior inside materials and provide theoretical basis for material design and performance optimization. The mechanical property and damage evolution of the proposed model is predicted and analyzed using finite element (FE) analysis and progressive damage method. The maximum errors of equivalent stiffness and strength between prediction and experimental values are 6.7% and 2.3%, respectively. The results show that the proposed model has high prediction accuracy and can reasonably reflect the damage extension and ultimate failure mode of the material during the loading process, which verifies the rationality of the proposed unit-cell modeling strategy. The modeling method proposed in this paper provides a new perspective for the in-depth understanding and description of the microstructure and mechanical behavior of 2.5D-SSLS-WC materials, which is of significant theoretical and engineering value and can be extended to the modeling of other woven composites.

Evaluation and Comparison of Stresses Between All-on-4 and All-on-6 Treatment Concepts With Three Different Prosthetic Materials in the Maxilla: A Finite Element Analysis Study

Evaluation and Comparison of Stresses Between All-on-4 and All-on-6 Treatment Concepts With Three Different Prosthetic Materials in the Maxilla: A Finite Element Analysis Study

Toward painless road-cycling for women: Innovative pressure distribution through lattice-based seat pads

Potential health risks for male athletes in professional road cycling are numerously investigated. For female athletes, necessary information is missing and thus there is a lack of equipment meeting their specific needs. The different pelvic anatomy of women compared to men suggests different saddle designs, different cycling short pads, and even different types of material to avoid pain and health problems. To collect data for a systematic development of pads specifically for women, we performed a study with 29 ambitious female athletes, who road cycle long distances (>90 min) at least once a week. First, we documented each athlete’s recent cycling situation, including the perceived comfort, grievances and the equipment used. Second, molds of the pelvis-saddle interfaces were generated using a previously developed measurement saddle to analyze pressure distributions during both static and dynamic loading. Measures were taken using the idmatch system following a bike fitting, which suggested a bicycle setup incorporating, among other factors, the individual athlete’s anthropometric data. Molds were subsequently digitized with a calibrated 3D scanner. Third, the digital pressure data resulting from the molds was analyzed considering its ability to represent interindividual differences, which validated the developed measurement saddle. Finally, a novel lattice-based pad prototype was designed based on the measured pressure data. Finite element analyses (FEA) were carried out to observe mechanical loads in the lattice structure and enable an optimization of the design. The prototype was additively manufactured using stereolithography (SLA).

Study of Unsymmetrical Magnetic Pulling Force and Magnetic Moment in 1000 MW Hydrogenerator Based on Finite Element Analysis

The large dimensions of the 1000 MW hydroelectric generator sets require high mounting accuracy. Small deviations can lead to asymmetry, which in turn triggers unbalanced magnetic pulls and moments. Therefore, symmetry is a central challenge in the installation and operation of giant hydroelectric generators. In this paper, the effects of radial eccentricity, axial offset, and rotor shaft deflection on the unbalanced magnetic pull and moment are investigated by transient finite element analysis of the asymmetric magnetic field. The results of the time-domain and frequency-domain analyses show that asymmetric operation generates unbalanced magnetic forces and moments. These forces and moments increase linearly with increasing offset or deflection rate. When the eccentricity meets the installation criteria, the unbalanced magnetic pull forces are small and within acceptable limits. This study helps to understand the relationship between asymmetry and unbalanced magnetic pulling forces in large hydroelectric generators, and provides a theoretical basis for standardizing installation deviation control.

Automatic High-Resolution Operational Modal Identification of Thin-Walled Structures Supported by High-Frequency Optical Dynamic Measurements.

High-frequency optical dynamic measurement can realize multiple measurement points covering the whole surface of the thin-walled structure, which is very useful for obtaining high-resolution spatial information for damage localization. However, the noise and low calculation efficiency seriously hinder its application to real-time, online structural health monitoring. To this end, this paper proposes a novel high-resolution frequency domain decomposition (HRFDD) modal identification method, combining an optical system with an accelerometer for measuring high-accuracy vibration response and introducing a clustering algorithm for automated identification to improve efficiency. The experiments on the cantilever aluminum plate were carried out to evaluate the effectiveness of the proposed approach. Natural frequency and damping ratios were obtained by the least-squares complex frequency domain (LSCF) method to process the acceleration responses; the high-resolution mode shapes were acquired by the singular value decomposition (SVD) processing of global displacement data collected by high-speed cameras. Finally, the complete set of the first nine order modal parameters for the plate within the frequency range of 0 to 500 Hz has been determined, which is closely consistent with the results obtained from both experimental modal analysis and finite element analysis; the modal parameters could be automatically picked up by the DBSCAN algorithm. It provides an effective method for applying optical dynamic technology to real-time, online structural health monitoring, especially for obtaining high-resolution mode shapes.

A calculation method for ultimate and allowable loads in high-pressure thick-walled worn casing

Casing wear has become a critical issue in oil and gas drilling, significantly reducing casing burst strength. As exploration and development progress, the number of high-pressure, ultra-deep wells continues to rise, requiring high-strength, thick-walled casings capable of withstanding ultra-high internal pressures. However, research on the strength characteristics of worn high-strength, thick-walled casings under such conditions remains limited. This study fills that gap by quantitatively evaluating worn casings to determine the maximum allowable internal pressure, particularly for high-pressure, thick-walled casings. A systematic analysis of existing methods for calculating the ultimate load of casings is conducted, and a suitable approach for high-grade steel casings is proposed. A parametric finite element model (FEM) of worn casings was developed to assess the impact of various dimensionless structural parameters, including the thickness ratio (Do/t), wear percentage (h/t), wear circle ratio (2ri/Do), and nominal yield strength (Rp0.2), on the ultimate load. The results demonstrate that both wear depth and casing dimensions significantly affect the ultimate load. A new formula is proposed for calculating the ultimate and allowable loads of worn casings based on the results of a finite element analysis. This formula is applicable to high-strength casings of varying wall thicknesses, particularly under ultra-high pressure.

Finite element analysis of ductility and flexural capacity of FRP and steel bars hybrid reinforced concrete beams

AbstractTo study the flexural behavior of hybrid reinforced concrete (hybrid‐RC) beams with FRP and steel bars, this paper used ABAQUS finite element (FE) software to model and nonlinear analyze the hybrid‐RC beams and investigate the effects of effective reinforcement ratio, concrete strength, and FRP bars type on the flexural behavior of hybrid‐RC beams. In addition, the FRP bars stress, flexural bearing capacity, and ductility formulas for hybrid‐RC beams were fitted based on the FE results, and existing literature data were used to verify their accuracy. The FE model results indicated that the effective reinforcement ratio, FRP bars type, and concrete strength significantly impacted the flexural bearing capacity and deformation performance of hybrid‐RC beams. Increasing the strength of concrete improved the flexural bearing capacity and ductility of hybrid‐RC beams; increasing the effective reinforcement ratio and the elastic modulus of FRP bars increased the flexural bearing capacity of the hybrid‐RC beams but decreased its ductility. In addition, the fitted FRP bars stress, flexural bearing capacity, and ductility calculation formulas can quickly and conveniently predict the flexural bearing capacity and ductility of hybrid‐RC beams.