3D Finite Element Model Research Articles

A facile approach for enhancing mechanical resilience, and corrosion protection in epoxy coatings using bismuthene nanosheets

AbstractThis study presents novel mechanochemical methods for the synthesis and chemical modification of bismuthene nanosheets (BINS) using a high‐speed blender and planetary ball milling. Atomic force microscopy (AFM) measurements confirmed successful exfoliation of 1.5‐nm BINS. Epoxy/BINS nanocomposites exhibited enhanced mechanical properties, thermal stability, and chemical resistance. Chemical modification via ball milling improved the interface and dispersion of BINS within the epoxy matrix, leading to significant enhancements in mechanical performance and chemical resistance. Compared to neat epoxy, at 0.75 vol% m‐BINS, Young's modulus, impact strength and fracture toughness KIC were respectively enhanced by 30%, 88.6%, and 144.4% while these increments were 10%, 55.7%, and 97.8% for pristine BINS‐based epoxy nanocomposite. A 3D finite element model of the impact test of the nanocomposite was developed to predict its behavior under high‐strain rate loadings; the numerical model showed high agreement with experimental measurements. Epoxy/m‐BINS nanocomposites demonstrated exceptional chemical resistance, attributed to the small lateral dimensions of m‐BINS, which fill the spaces between cross‐linked epoxy molecules and uniformly distribute within the matrix. These findings highlight the crucial role of interface and dispersion in defining the mechanical properties of nanocomposites. Overall, this study provides a facile and scalable method for synthesizing and modifying bismuthene, showcasing its potential for developing functional polymer nanocomposites.Highlights Bismuthene nanosheets & modified BINS (m‐BINS) are prepared by eco‐friendly method. m‐BINS is ~1.5 nm thick and ~0.5 μm wide. m‐BINS shows good dispersion and strong interface adhesion within epoxy matrix. Impact strength and KIC of epoxy/m‐BINS nanocomposite are enhanced by 88.6% and 144.4%. Numerical model for impact strength is developed to predict behavior at high‐strain rate.

Numerical simulation of fabric cold pad-batch winding and quality assessment of fabric in roll

Proper fabric winding quality is crucial for achieving desired finishing effects in cold pad-batch dyeing. In this work, a detailed 3D finite element model and assessment criteria were established to analyze the influences of winding pattern, pick-up, and tension function on fabric winding quality, revealed the complex relationship between winding process and fabric roll shape. Material viscoelasticity’s time-dependent effects on stress distribution were considered. Results show that employing a following roller effectively suppresses tangential creases and axial streaks but increases seam imprints and reduces fabric roundness. Increasing pick-up improves winding quality by reducing creases, streaks, and compression deformations. However, it also elevates internal radial stress, hindering control over seam imprints. Winding with variable tension, conicity coefficient α and power index i have significant impacts on coiling quality. In addition, increasing α or decreasing i effectively enhances winding quality, with the power function performing better in tension adjustment and overall winding quality.

Numerical Prediction of Ride Comfort of Tracked Vehicle Equipped with Novel Flexible Road Wheels

Enhancing ride comfort has always constituted a crucial focus in the design and research of modern tracked vehicles, heavily reliant on the driving system’s performance. While the road wheel is a key component of the driving system, traditional road wheels predominantly adopt a solid structure, exhibiting subpar adhesion performance and damping effects, thereby falling short of meeting the demands for high-speed, stable, and long-distance driving in tracked vehicles. Addressing this issue, this paper proposes a novel type of flexible road wheel (FRW) characterized by a catenary construction. The study investigates the ride comfort of tracked vehicles equipped with flexible road wheels by integrating finite element and vehicle dynamic. First, three-dimensional (3D) finite element (FE) models of both flexible and rigid road wheels are established, considering material and contact nonlinearities. These models are validated through a wheel radial loading test. Based on the validated FE model, the paper uncovers the relationship between load and radial deformation of the road wheel, forming the basis for a nonlinear mathematical model. Subsequently, a half-car model of a tracked vehicle with seven degrees of freedom is established using Newton’s second law. A random road model, considering the track effect and employing white noise, is constructed. The study concludes by examining the ride comfort of tracked vehicles equipped with flexible and rigid road wheels under various speeds and road grades. The results demonstrate that, in comparison to the rigid road wheel (RRW), the flexible road wheel enhances the ride comfort of tracked vehicles on randomly uneven roads. This research provides a theoretical foundation for the implementation of flexible road wheels in tracked vehicles.

Evaluating the biomechanical effects of pedicle subtraction osteotomy at different lumbar levels: a finite element investigation

BACKGROUNDPedicle subtraction osteotomy (PSO) is effective for correcting spinal malalignment but is associated with high complication rates. The biomechanical effect of different PSO levels remains unclear, and no finite element (FE) analysis has compared L2-, L3-, L4-, and L5-PSOs. PURPOSETo assess the effects of PSO level on the spine's global range of motion, stresses on posterior instrumentation, load sharing with the anterior column, and proximal junctional stresses. STUDY DESIGNA computational biomechanical analysis. METHODSA validated 3D spinopelvic FE model (T10-Pelvis) was used to perform PSOs at L2, L3, L4 and L5. Each model was instrumented with a 4-rod configuration (primary rods + in-line satellite rods) from T11-Pelvis. Simulation included a 2-step analysis; (1) applying 300 N to thoracic, 400 N to lumbar, and 400 N to sacrum, and (2) applying a 7.5 Nm moment to the top endplate of the T10 vertebral body. Acetabulum surfaces were fixed in all degrees of freedom. The range of motion, spinopelvic parameters (lumbar lordosis [LL], sacral slope [SS], pelvic incidence [PI], and pelvic tilt [PT]), PSO force, and von Mises stresses were measured. All models were compared with the L3-PSO model and percentage differences were captured. RESULTSCompared to the intact alignment: LL increased by 48%, 45%, 59%, and 56% in the L2-, L3-, L4-, and L5-PSO models; SS increased by 25%, 15%, and 11% while PT decreased by 76%, 53%, and 45% in L2-, L3-, and L4-PSOs (SS and PT approximated intact model in L5-PSO); Lumbar osteotomy did not affect the PI. Compared to L3-PSO: L2-, L4-, and L5-PSOs showed up to 32%, 34%, and 34% lower global ROM. The least T10-T11 ROM was observed in L5-PSO. The left and right SIJ ROM were approximately similar in each model. Amongst all, the L5-PSO model showed the least ROM at the SIJ. Compared to L3-PSO, the L2-, L4-, and L5-PSO models showed up to 67%, 61%, and 78% reduced stresses at the UIV, respectively. Minimum stress at UIV+ was observed in the L3-PSO model. The L2-and L3-PSOs showed the maximum PSO force. The L5-PSO model showed the lowest stresses on the primary rods in all motions. CONCLUSIONOur FE investigation indicates that L5-PSO results in the greatest lumbar lordosis and lowest global, SIJ, and T10-T11 ROMs and stresses on the primary rods, suggesting potential mechanical benefits in reducing the risk of rod breakage. However, L4- and L5-PSOs led to the least force across the osteotomy site, which may increase the risk of pseudarthrosis. These findings provide biomechanical insights that may inform surgical planning, though further clinical investigation is essential to determine the optimal PSO level and validate these results. CLINICAL SIGNIFICANCEUnderstanding the biomechanical impact of PSO level is crucial for optimizing surgical outcomes and minimizing the risks of postoperative complications.

Coupled Eulerian–Lagrangian model prediction of neural tissue strain during microelectrode insertion

Objective.Implanted neural microelectrodes are an important tool for recording from and stimulating the cerebral cortex. The performance of chronically implanted devices, however, is often hindered by the development of a reactive tissue response. Previous computational models have investigated brain strain from micromotions of neural electrodes after they have been inserted, to investigate design parameters that might minimize triggers to the reactive tissue response. However, these models ignore tissue damage created during device insertion, an important contributing factor to the severity of inflammation. The objective of this study was to evaluate the effect of electrode geometry, insertion speed, and surface friction on brain tissue strain during insertion.Approach. Using a coupled Eulerian-Lagrangian approach, we developed a 3D finite element model (FEM) that simulates the dynamic insertion of a neural microelectrode in brain tissue. Geometry was varied to investigate tip bluntness, cross-sectional shape, and shank thickness. Insertion velocities were varied from 1 to 8 m s-1. Friction was varied from frictionless to 0.4. Tissue strain and potential microvasculature hemorrhage radius were evaluated for brain regions along the electrode shank and near its tip.Main results. Sharper tips resulted in higher mean max principal strains near the tip except for the bluntest tip on the square cross-section electrode, which exhibited high compressive strain values due to stress concentrations at the corners. The potential vascular damage radius around the electrode was primarily a function of the shank diameter, with smaller shank diameters resulting in smaller distributions of radial strain around the electrode. However, the square shank interaction with the tip taper length caused unique strain distributions that increased the damage radius in some cases. Faster insertion velocities created more strain near the tip but less strain along the shank. Increased friction between the brain and electrode created more strain near the electrode tip and along the shank, but frictionless interactions resulted in increased tearing of brain tissue near the tip.Significance. These results demonstrate the first dynamic FEM study of neural electrode insertion, identifying design factors that can reduce tissue strain and potentially mitigate initial reactive tissue responses due to traumatic microelectrode array insertion.

To Evaluate the Favourable Distribution Pattern of Stress in Maxilla and Mandible during Maxillary Protraction Using Miniplates of Varying Diameters and Thread Pitches under Different Levels of Inter Maxillary Forces: A Study Using Finite Element Analysis

Introduction The aim of the study is to compare the stress distribution pattern by three different diameters of miniplate (1.5 mm, 2 mm, 2.5 mm) of three different mini- implant thread pitches (0 .5 mm, 1 mm, 1.5 mm), in the maxilla and mandible during maxillary protraction using different inter-maxillary elastic force of (2 N,4N,6N,8 N).  Materials and Methods Using Autocad software and plate geometry, a 3D finite element model of the maxilla was made with a miniplate at the infrazygomatic buttress and a mandibular miniplate at the mandibular parasymphysis. Stress distributions and displacements were analyzed in Von Mises stress form using Ansys software.  Results In the implant study, the Von Mises stress in bone (Mpa) was 142 Mpa for the 1 mm diameter implant, which was the lowest compared to 170 Mpa for the 0.5 mm pitch and 233 Mpa for the 1.5 mm pitch. Whereas in skull study when 2N elastic force was applied for a 2 mm diameter minimplant, the maximum Von Mises stress at 0.5mm,1mm and 1.5mm thread pitch was (18.454 Mpa, 18.47 Mpa, and 18.344 Mpa. For elastic force of 4N was (18,465 Mpa, 18.492 Mpa and 18.244 Mpa), for 6N elastic force was 18.388 Mpa, 18.43 Mpa and 18.086 Mpa), and for 8N was (18.272 Mpa, 18.324 Mpa and 17.883 Mpa), which was similar compared from other two diameters.  Conclusion When comparing 1.5 mm, 2 mm, and 2.5 mm diameter implants with 0.5 mm, 1 mm, and 1.5 mm pitch thread , the 2 mm diameter at 1 mm pitch thread shows the least strained bone in the implant study. Whereas,in the skull study, 2 mm diameter mini-implants had similar stress distribution in the maxilla and mandible,in all the thread pitches and elastic force which shows pitch variants and different force application is not a factor for stress distribution in the bone.

Blast Performance of Polyurea-Coated Modular Structure Composed of Fiber-Reinforced Polymer and Foam Sandwich Panels

Lightweight modular structures have become a requirement in today’s world, especially for areas that are prone to occurrence of extreme events, such as earthquakes and blasts, and are situated in difficult terrains with challenging accessibility. Sandwiched composites can be one of the most suitable building units for construction of these structures due to their engineered mechanical and physical properties. Therefore, in this numerical study, performance assessment of a sandwich modular structure in the shape of a truncated cylinder is conducted under blast load. The sandwich modular structure is composed of flat and curved carbon fiber-reinforced polymer (CFRP) and extruded polystyrene (XPS) foam sandwich panels. A three-dimensional (3D) finite element (FE) model of the sandwich modular structure is developed considering the orthotropic behavior of CFRP facesheets and the crushing foam behavior is accounted for the XPS foam core in the FE modeling. The damage assessment in the CFRP facesheet is performed using Hashin’s damage criterion. Furthermore, the effect of polyurea with varying thicknesses on the blast-resistance of the structure is investigated. The polyurea is modeled as hyperelastic material using the Mooney-Rivlin model. The influence of polyurea positioning is studied when (a) applied externally to flat and curved walls of the structure directly exposed to the blast and (b) applied internally to flat and curved walls of the structure opposite to the exposure of the blast (rear face). It is observed that the flat walls of the structure are more vulnerable to the blast load than the curved walls of the structure. Moreover, a quadratic and linear reduction in the deflection of flat and curved walls with increasing thickness of polyurea coating is obtained, respectively. In addition, with increasing thickness of the additional polyurea coating, a logarithmic reduction in the kinetic energy of the sandwich modular structure is reported.

The effect of screw insertion configuration of Sinus Tarsi plate on biomechanical performance using finite element analysis

Sinus Tarsi plates are used as implants for minimally invasive surgery of calcaneus bone fractures. This study evaluated the screw fixation patterns of Sinus Tarsi plates for optimal biomechanical performance. Six three-dimensional (3D) finite element models with different positional screws were evaluated for calcaneus fracture stabilization using Sinus Tarsi plates with 5, 6, and 7 holes. Walking stance conditions as heel strike, midstance, and push-off phases were used to compare loading. Results indicated that the equivalent (EQV) stress exhibited in the implant was higher than in the surrounding bone, with the highest value during the push-off phase. The maximum EQV stress or risk of failure decreased when an insertion screw was placed in the anterior bone using a 7-hole plate, and the most stable strain result at the fracture bone site was recorded for a Sinus Tarsi plate with 7 holes (TT 7-1). The screw insertion pattern and configuration of the Sinus Tarsi plate impacted the biomechanical performance of the calcaneal fracture.

Delamination detection in composite pipes using higher harmonic generation of flexural waves

This paper investigates delamination detection in composite pipes using higher harmonic generation technique for the first time. The semi-analytical finite element (SAFE) method is developed to analyze the dispersion characteristics of the composite pipe. Then, a flexural mode at low frequency is selected to detect delamination. The three-dimensional (3D) finite element (FE) model is developed to simulate the flexural mode propagating in the composite pipe and its interaction with delamination. By comparing the simulated radial displacement signals with and without delamination, it is observed that the delamination can contribute to the higher harmonic generation. Subsequently, the ultrasonic measurements are conducted to demonstrate the numerical results. Using a relatively simple piezoelectric transducer (PZT) configuration, an almost pure flexural mode can be excited in the experiment. More importantly, experimental results indicate the higher harmonics induced by the delamination can be observed obviously. Finally, extensive parametric studies are performed to reveal the sensitivity of higher harmonics to the delamination with various sizes and at different interface. The proposed higher harmonic generation of flexural waves is promising for the practical application of delamination detection in composite pipes.

Finite element modeling of active cracking in actively reinforced concrete pavement slab exposed to fluctuating temperature

The continuously reinforced concrete pavement (CRCP) system grapples with challenges such as non-uniform transverse crack patterns and the need for substantial reinforcement. Field research on the Belgian CRCP sections along motorway E313 indicates that active cracking induced by partial surface saw-cuts consistently leads to transverse crack patterns. This study introduces an innovative modification to the CRCP: the actively reinforced concrete pavement design (ARCP). The ARCP leverages partial surface saw-cuts to reduce reinforcement needs by replacing continuous-length steel bars with partial-length counterparts. The main objective of the present study is to develop a 3D finite element (FE) model capturing the active cracking behavior of ARCP under realistic external temperature variations. Comparative analysis with CRCP considers early-age crack patterns, crack strain development, and the distribution of maximum steel stress for different steel ratios (0.67%, 0.75%, and 0.85%). FE simulation results align with field data, indicating that ARCP exhibits similar early-age cracking behavior to CRCP but with a significant 24 to 42% reduction in total reinforcement. This innovation presents a promising avenue for addressing CRCP challenges while optimizing material usage in pavement construction.

Fatigue life prediction of friction-stir-welded aluminum bridge decks – Experimental tests and numerical framework

This paper presents the results of experimental tests and proposes a numerical framework for the prediction of the fatigue behaviour of friction stir welded (FSW) butt-lap joints of aluminium bridge deck extrusions. Fatigue test specimens made of welded real roadway bridge deck extrusions were subjected to cyclic bending under different loading conditions. The fatigue failure modes were thoroughly analyzed. A numerical framework incorporating a 2D finite element (FE) model based on the theory of critical distances (TCD) and a simplified linear elastic fracture mechanics (LEFM) model was developed to predict the fatigue failure initiation location and the fatigue life of the specimens under the test conditions. The location of the failure initiation played a key role in the choice of the numerical approach adopted in the prediction of fatigue life. For fatigue failures initiating from the base metal, the framework utilizes the TCD formulations while for failures in the weld joint, the LEFM model was applied. The proposed numerical framework showed a good agreement with the experimental data.

Real-time dynamic and structural behavior estimation of a steel lazy wave riser through finite-element-based digital twin and hull-motion sensor

A digital twin (DT) method is proposed to estimate the dynamic and structural behaviors of a Steel Lazy Wave Riser (SLWR) under environmental conditions. This method uses a 1D finite element (FE) riser model that can include various loads and boundary conditions measured from sensors. We selected a spread-moored Floating Production Storage and Offloading (FPSO) vessel to validate the proposed method, which hosts multiple Production and Injection SLWRs. Using the time-domain dynamics simulation program, we built a reference model considering the fully coupled FPSO with mooring lines and risers in various wind/wave/current conditions. The synthetic sensor data, which represents the motions and internal fluid density changes, were generated from the simulation of the reference model. Then, two riser DT models, the Top Oscillation Model (TOM) and the Two-Point Oscillation Model (TPOM), were built, considering only a single riser made of the 1D FE model. TOM employed vessel motions as boundary conditions while internal fluid density and ocean current could be inputted as external loads. TPOM incorporated an additional motion sensor attached to the riser. The motion data obtained from the reference model were first inputted into the respective riser DT models. Next, we further evaluated their performance with and without the estimated ocean currents and slugs of internal fluid. The time histories, spectra, and statistical data of displacements and stresses along the riser were systematically compared and analyzed for various test cases and environments. While the hull-motion sensor alone can provide practically acceptable results using the developed methodology, additional consideration of current load and internal fluid's density variation improves the overall riser monitoring performance. The present method can significantly reduce the number of sensors compared to traditional riser monitoring methods.

A novel damage localization technique for type III composite pressure vessels based on guided wave mode-matching method

Damage monitoring during the service life of Type III composite overwrapped pressure vessels (COPVs) is crucial for ensuring their safe operation. This paper focuses on the damage localization in COPVs using ultrasonic guided waves structural health monitoring (SHM) techniques. Firstly, dispersion curves were plotted to establish a foundation for experiments and simulations based on the propagation theory of guided waves in multilayered anisotropic structures. Subsequently, a 3D finite element model of COPV was constructed to capture the propagation characteristics of guided waves within the COPV and their interaction with damage. The effects of different fiber angles and fiber layer numbers on guided waves propagation were analyzed, and their interrelationships were established. Furthermore, the “Wave Velocity Directionality” effect of the A0 mode was identified during its propagation in COPV. The monitoring signals obtained from experiments were analyzed to assess the impact of damage on the time-domain and frequency-domain signals of guided waves. Finally, a damage localization algorithm based on mode-matching was proposed, and its localization accuracy was verified in COPVs with different damage locations and fiber layer numbers. The results demonstrate the significant potential of the proposed damage localization algorithm in the damage monitoring of COPV structures.

Comparative studies on the seismic performances of precast segmental columns with different concrete, reinforcement and tendon materials

In recent years, precast segmental columns cast with ordinary Portland cement (OPC) and reinforced with steel rebars have gained popularity in engineering practices owing to its obvious advantages. However, the use of OPC in the construction associates to significant emission of carbon dioxide. Moreover, the corrosion of steel reinforcements and tendon are unavoidable during the lifetime of the structure, which will significantly lower the structural strength and durability. To overcome these issues, very recently, this study proposes using green and sustainable construction materials, i.e., the geopolymer concrete (GPC), together with basalt fibre reinforced polymer (BFRP) reinforcements and tendons, which possess the characteristics of less CO2 emission and excellent corrosion resistant capability, to construct precast segmental columns (i.e., to construct GPC-BFRP segmental columns) for seismic resistant applications. Experimental studies on the proposed GPC-BFRP and the conventional OPC-steel segmental columns were then performed to examine the performances of the proposed design. However, the comparisons of the experimental results were not strictly fair since the key parameters of the two types of columns, e.g., concrete strength and posttension force, in the experiments could not exactly be the same even though they were designed to be the same. This paper therefore extends the recent experimental study and performs numerical simulations. In particular, the experimentally tested columns were used to validate the three-dimensional (3D) finite element models (FEMs) of the two segmental columns with different materials (i.e., OPC-steel and GPC-BFRP). The validated numerical models are then used to examine the seismic performances of these two types of columns under the same design parameters. Numerical results show that under small earthquakes, two types of columns present almost identical structural responses. Under moderate to severe earthquakes, the two columns also have comparable performances, but GPC-BFRP segmental column presents larger displacement responses and failed earlier because of the smaller BFRP elastic modulus. The results in this study demonstrate the potentials of constructing sustainable and durable GPC-BFRP segmental columns in seismic regions.

Thermal Conductivity of AlSi12/Al2O3-Graded Composites Consolidated by Hot Pressing and Spark Plasma Sintering: Experimental Evaluation and Numerical Modeling

Functionally graded metal matrix composites have attracted the attention of various industries as materials with tailorable properties due to spatially varying composition of constituents. This research work was inspired by an application, such as automotive brake disks, which requires advanced materials with improved wear resistance on the outer surface as combined with effective heat flux dissipation of the graded system. To this end, graded AlSi12/Al2O3 composites (FGMs) with a stepwise gradient in the volume fraction of alumina reinforcement were produced by hot pressing and spark plasma sintering techniques. The thermal conductivities of the individual composite layers and the FGMs were evaluated experimentally and simulated numerically using 3D finite element (FE) models based on micro-computed X-ray tomography (micro-XCT) images of actual AlSi12/Al2O3 microstructures. The numerical models incorporated the effects of porosity of the fabricated AlSi12/Al2O3 composites, thermal resistance, and imperfect interfaces between the AlSi12 matrix and the alumina particles. The obtained experimental data and the results of the numerical models are in good agreement, the relative error being in the range of 4 to 6 pct for different compositions and FGM structure. The predictive capability of the proposed micro-XCT-based FE model suggests that this model can be applied to similar types of composites and different composition gradients.

3D electromagnetic assessment of bended CORC® cables

Conductor on round core (CORC®) cables have emerged as a leading contender in high-temperature superconducting (HTS) cable designs, offering exceptional performance with current densities surpassing 300 A/mm2 and the ability to withstand high axial tensile and compressive strain. Despite their remarkable properties, optimizing CORC® cables remains a challenge, particularly in accurately estimating their AC losses under real-world conditions, which necessitates advanced numerical modeling techniques. Building upon recent advancements in simulating straight CORC® cables, where Bean’s-like current profiles were observed across the actual thickness of wound superconducting tapes, we introduce a tailored computational approach to enhance the processing speed of three-dimensional (3D) finite element models of wound HTS tapes. This tailored approach is specifically designed to address the complexities of bent CORC® cables, which exhibit helicoidal winding and are subjected to varying mechanical strain. We focus on analyzing their electromagnetic performance by transitioning from idealized straight-former designs to more realistic scenarios where cable-formers are bent to accommodate flexible cable routing or coil configurations. Our simulations consider a typical cable design comprising three 4 mm-wide SuperPower tapes (SCS4050) with a twist pitch of 40 mm. We demonstrate the capability to accurately model the full electromagnetic behavior of bent CORC® cables without the reduction of degrees of freedom, providing valuable insights into their performance under bending conditions. Our findings contribute to the ongoing optimization of CORC® cable designs for a wide range of practical applications in high-current and high-magnetic field environments.

On the numerical assessment of bending- and torsion-induced stresses in idealised sawn timber beams

ABSTRACT When designing timber beams for bending, shear and torsion, it is common engineering practice to use analytical formulas that neglect the cylindrical nature of the orthotropic material, the annual ring orientation, spiral grain and so on. While they result in stresses that appear reasonable, the approach is in principle theoretically flawed. In this paper a 3D finite element model is used to analyse the stress levels in sawn timber beams, taking into account the radially varying and cylindrically orthotropic material parameters, as well as a number of geometrical features. The beams are assumed to be mechanically idealised without imperfections. Parametric analyses indicate that especially the annual ring orientation has a significant impact on the maximum stresses, even though the cross-sectional stress distributions have distinct similarities with common beam theory. Furthermore, a Monte Carlo simulation is performed, randomly varying all parameters within given intervals. The simulations reveal that the maximum stresses from the finite element model, in almost all cases are noticeably larger than predicted by the analytical formulas, rendering them on the unsafe side in a theoretical sense.

Finite element simulation of treatment with locking plate for distal fibula fractures.

An improved Finite Element Model(FEM) is applied to compare the biomechanical stability of plates with three different options in the treatment of distal fibula fractures in this study. The Computed Tomography(CT) scan of the knee to ankle segment of a volunteer was performed. A 3D fibula FEM was reconstructed based on the CT data. Three different loads (uni-pedal standing, torsion, and twisting) were applied, the same as in the experiments in the literature. The stresses and strains of the three options were compared under the same loads, using a 4-hole locking plate (Option A), a 5-hole locking plate (Option B), and a 6-hole locking plate (Option C) in a standard plate for lateral internal fixation. The simulation results show that all three options showed a stress masking effect. Option C had the best overall biomechanical performance and could effectively distribute the transferred weight. This is because option C has greater torsional stiffness and better biomechanical stability than options A and B, and therefore, option C is the recommended internal fixation method for distal fibula fractures. The Finite Element Analysis(FEA) method developed in this work applies to the stress analysis of fracture treatment options in other body parts.

Using Finite Element Models to Assess Spinal Cord Biomechanics after Cervical Laminoplasty for Degenerative Cervical Myelopathy.

Cervical laminoplasty is an established motion-preserving procedure for degenerative cervical myelopathy (DCM). However, patients with pre-existing cervical kyphosis often experience inferior outcomes compared to those with straight or lordotic spines. Limited dorsal spinal cord shift in kyphotic spines post-decompression and increased spinal cord tension may contribute to poor neurological recovery and spinal cord injury. This study aims to quantify the biomechanical impact of cervical sagittal alignment on spinal cord stress and strain post-laminoplasty using a validated 3D finite element model of the C2-T1 spine. Three models were created based on the C2-C7 Cobb angle: lordosis (20 degrees), straight (0 degrees), and kyphosis (-9 degrees). Open-door laminoplasty was simulated at C4, C5, and C6 levels, followed by physiological neck flexion and extension. The results showed that spinal cord stress and strain were highest in kyphotic curvature compared to straight and lordotic curvatures across all cervical segments, despite similar segmental ROM. In flexion, kyphotic spines exhibited 103.3% higher stress and 128.9% higher strain than lordotic spines and 16.7% higher stress and 26.8% higher strain than straight spines. In extension, kyphotic spines showed 135.4% higher stress and 241.7% higher strain than lordotic spines and 21.5% higher stress and 43.2% higher strain than straight spines. The study shows that cervical kyphosis leads to increased spinal cord stress and strain post-laminoplasty, underscoring the need to address sagittal alignment in addition to decompression for optimal patient outcomes.

Digital Image Correlation and Ultrasonic Lamb Waves for the Detection and Prediction of Crack-Type Damage in Fiber-Reinforced Polymer Composite Laminates.

The possibility of using the Digital Image Correlation (DIC) technique, along with Lamb wave analysis, was investigated in this study for damage detection and characterization of polymer carbon fiber (CFRP) composites with the help of numerical modeling. The finite element model (FEM) of the composite specimen with artificial damage was developed in ANSYS and validated by the results of full-field DIC strain measurements. A quantitative analysis of the damage detection capabilities of DIC structure surface strain measurements in the context of different defect sizes, depths, and orientation angles relative to the loading direction was conducted. For Lamb wave analysis, a 2D spatial-temporal spectrum analysis and FEM using ABAQUS software were conducted to investigate the interaction of Lamb waves with the different defects. It was demonstrated that the FEM updating procedure could be used to characterize damage shape and size from the composite structure surface strain field from DIC. DIC defect detection capabilities for different loadings are demonstrated for the CFRP composite. For the identification of any composite defect, its characterization, and possible further monitoring, a methodology based on initial Lamb wave analysis followed by DIC testing is proposed.