Nonlinear Finite Element Analysis Research Articles

Nonlinear Finite Element analysis of concrete corbels with hybrid reinforcements

This study utilizes nonlinear finite element analysis to simulate the structural response of Reinforced Concrete (RC) corbels with hybrid reinforcements under monotonic loading. The models implemented in ABAQUS examine RC corbels with combined Carbon Fiber Reinforced Polymer (CFRP) and steel reinforcing bars to study the interaction between the concrete and hybrid reinforcement system. Specifically Ultimate load capacity, energy absorption and failure mode. Compressive strength, shear span/depth ratio, and the ratio of CFRP/steel reinforcement were the main parameters that considered in this paper. Results demonstrated a significant improvement in the ultimate load capacity of concrete corbels by up to 53% when both conventional steel and CFRP bars were integrated within the concrete corbel. The numerical test outcomes revealed that an increased hybrid reinforcement ratio effectively managed crack distribution, resulting in reduced concrete crack widths.

Transverse compressive behavior of plain and polypropylene fiber-reinforced concrete infilled steel tubes as hybrid steel-concrete nodes for discrete reticulated shell structures

This study investigates using concrete infilled steel tubes as hybrid nodes for discrete reticulated shell structures under compressive loading transverse to the tube axis. Three configurations were tested: empty, plain concrete infilled and polypropylene fiber-reinforced concrete infilled steel tubes. Displacement-controlled loading was applied through welded steel plates. Simplified beam theory models and nonlinear finite element analysis were used to evaluate the structural behavior. The concrete infilled steel tube specimens had higher stiffness and load-bearing capacity than the empty ones. The structural behavior of the concrete infilled specimens could be split into pre- and post-split-tensile cracking phases. No significant difference was found between the plain and fiber-reinforced concrete specimens under loads up to 1500 kN, which was the load limit of the testing machine. An additional fiber-reinforced concrete specimen, tested on a higher capacity machine, had a load-bearing capacity of 2400 kN and exhibited ductile failure.

Explainable machine learning models for predicting the ultimate bending capacity of slotted perforated cold-formed steel beams under distortional buckling

This study develops explainable machine learning (ML) models to predict the ultimate bending capacity of cold-formed steel (CFS) beams with staggered slotted perforations, focusing on distortional buckling behavior. Utilizing a dataset from 432 non-linear finite element analysis simulations of CFS Lipped channels, ten ML algorithms, including four basic and six ensemble models, were evaluated. Ensemble models, specifically CatBoost and XGBoost, demonstrated superior accuracy, with test-set performances reaching a coefficient of determination (R2) of 99.9%, outperforming traditional analytical methods such as the Direct Strength Method (DSM). SHapley Additive Explanations (SHAP) were applied to highlight how features like plate thickness and root radius critically influence predictions. The findings underscore the enhanced predictive capabilities of ML models for structural performance, suggesting a significant potential to refine traditional design methodologies and optimize CFS beam designs.

Experimental and numerical investigation on RC beams with web openings subjected to pure torsion strengthened by ferrocement technique or GFRP sheets

The main objective of the current experimental and numerical study is to investigate the effect of strengthening by ferrocement layers on the behavior of reinforced concrete (RC) beams with openings subjected to pure torsion and compare it with the beams that were strengthened by Glass Fiber Reinforced Polymer (GFRP). The experimental investigation consists of twelve reinforced concrete (RC) beams that have been divided into four groups. The parameters under investigation included the strengthening technique (ferrocement or External Bonded Glass Fiber Reinforced Polymer EB-GFRP), type of steel mesh (welded wire mesh and expanded metal mesh), number of layers of mesh (1, 2, 3), extension length outside opening (50, 100 or 200) mm, strengthening configuration (full or U-shape) wrapping, and the anchoring system effect. The experimental work consists of one solid beam and eleven beams with openings. The tested beams yielded results such as cracking and ultimate torques, angle of rotation, and mechanism of failure. Creating an opening in the control solid beam resulted in a 38.46 % decrease in ultimate torque, while using different techniques during this research proved efficiency in the strengthening process. Using GFRP U-wrapping and fully wrapping to strengthen the area around the beam's opening increased the ultimate torque by 50 % and 81.25 %, respectively, compared to the un-strengthened beam with an opening. Adding fully wrapped ferrocement layers to the beam with an opening greatly improved its torsional strength. The ultimate torque increased by 40.63 % to 81.25 % compared to the beam with an unreinforced opening. Increasing the number of welded steel mesh layers from 1 to 3 in the ferrocement strengthening technique led to an increase in ultimate torque from 40.63 % to 75 % compared with the un-strengthened beam with the opening. The tests showed that using expanded metal mesh instead of welded wire mesh in strengthened beams with holes led to a 9.43 % higher ultimate torsional capacity, indicating that the expanded metal mesh worked better than the welded wire mesh. Using the U-shape ferrocement wrapping with anchors was better than without anchors, resulting in a 9.1 % increase in the ultimate torsional capacity. Applying a fully wrapped GFRP sheet or expanded metal mesh ferrocement strengthening achieved the highest ultimate torque, 81.25 % more than the un-strengthened beam with an opening. Moreover, a 3D non-linear finite element analysis is conducted using ABAQUS software to forecast the torsional properties of beams strengthened by either ferrocement or EB-GFRP. The numerical model captured the failure patterns, twisting angle, and ultimate load of tested beams. The experimental and analytical results were in good agreement. The research concluded the effectiveness of using the ferrocement reinforced with different steel mesh types in strengthening reinforced concrete beams with openings under pure torsion, the cost-efficiency and simplicity of ferrocement as a solution compared to its results with EB-GFRP techniques.

Study on Mechanical Properties of Steel-Strengthened Bamboo Beams with Webbing Opening

Bamboo beams are often reinforced with built-in steel sections to enhance their strength and load-bearing capacity. In this paper, we studied the effect of different parameters, including the location of the hole, the hole size, and the thicknesses of the steel and bamboo, on the mechanical properties of reinforced beams. The damage patterns, deformation characteristics, and force-transfer mechanisms, as well as the mechanical properties of reinforced beams with different hole shapes, underwent non-linear finite element analysis. The damage sustained by the reinforced bamboo beam differed from that of the traditional bamboo beam; two diagonal points formed a plastic hinge, mainly during the process of shear damage to the hole. It was determined that the hole size and the thickness of the bamboo have the greatest influence on the mechanical properties of the reinforced beam. The damage characteristics of the composited beams with different holes are similar; the bearing capacity of reinforced beams with open square holes is reduced by 10%–25%compared with circular holes.

A Novel Application of Computational Contact Tools on Nonlinear Finite Element Analysis to Predict Ground-Borne Vibrations Generated by Trains in Ballasted Tracks

Predictive numerical models in the study of ground-borne vibrations generated by railway systems have traditionally relied on the subsystem partition approach (segmented). In such a method, loads are individually applied, and the cumulative effect of the rolling stock is obtained through superposition. While this method serves to mitigate computational costs, it may not fully capture the complex interactions involved in ground-borne vibrations—especially in the frequency domain. Recent advancements in computation and software have enabled the development of more sophisticated vibrational contamination prediction models that encompass the entire dynamics of the system, from the rolling stock to the terrain, allowing continuous simulations with a defined time step. Furthermore, the incorporation of computational contact mechanics tools between various elements not only ensures accuracy in the time domain but also extends the analysis into the frequency domain. In this novel approach, the segmented models are shifted to continuous simulations where the nonlinear problem of a rigid–flexible multibody system is fully considered. The model can predict the impact of a high-speed rail (HSR) vehicle passing, capturing the key intricacies of ground-borne vibrations and their impact on the surrounding environment due to a deeper comprehension of the occurrences in the frequency domain.

Kineto-static analysis of a hybrid manipulator consisting of rigid and flexible limbs with locking function for planar shape morphing

The incorporation of lockable passive backbones into active compliant morphing systems efficiently results in lightweight, high-load, and large deformation systems. However, there exist challenges in kineto-static analysis due to the interaction between rigid reconfigurable kinematic constraints and the nonlinear deformation of actuated flexible limbs. This paper addresses these issues by developing a kineto-static method to analyze the motion in a novel planar 3-DOF shape-morphing manipulator. The manipulator features two actuated flexible limbs with a lockable variable geometry truss (LVGT). In this study, two isostatic topologies are selected for reconfigurable motion control under external tip loads. A multi-step sequential control strategy is proposed to maneuver the manipulator's platform for desired poses. Then, a constrained-trajectory-based kinematic model is proposed for an inverse kinematic solution considering motion planning. Subsequently, a kineto-static model is introduced, considering constraints from rigid and flexible limbs, aiming to distribute distributing redundant actuation forces. Finally, nonlinear finite element analysis (FEA) and experiments are carried out to validate the effectiveness of the proposed method.

Vibroacoustic simulation for truck tire tread noise prediction

In the last years, the introduction to the market of electric vehicles and a new labeling system introduced by the European Commission raised a strong interest in the noise produced by the tire-road interaction. The reduction of noise emissions became a strong challenge for the tire manufacturers that are constantly in need of developing new simulation tools capable of predicting the noise emitted by a tire. In this paper, the application of a simulation methodology capable of predicting the noise performance of a tire is shown and validated by means of experimental data. The experimental activities consisted of the acquisitions of noise produced by three truck tires made up of a particular tread pattern in which a single geometric feature is analyzed in each configuration, in a near field indoor condition. The simulation process aims to faithfully reproduce the procedure of the experimental test and involves the use of non-linear explicit finite element analysis followed by a vibroacoustic simulation to account for the radiated noise by structural vibrations and fluid-pumping.

Simulation study on the effect of palladium layer thickness and temperature on the bonding properties of palladium coated copper wire

Palladium coated copper (PCC) wire is an emerging bonding wire. There are relatively few studies on the effect of palladium plating thickness and temperature on its bonding performance. In order to investigate the effects of three parameters, namely palladium plating thickness, chip preheating temperature and the free air ball (FAB) initial temperature, on the bonding performance of PCC wires, this paper establishes a transient nonlinear finite element analysis model of thermal coupling between bare copper wires and PCC wires, and simplifies the whole bonding process into two stages of impact and ultrasonic vibration to carry out the experimental simulation. Firstly, the Taguchi orthogonal test method was adopted to obtain the ranking of the degree of influence of the three factors on the bonding results, and the optimum palladium plating thickness and FAB initial temperature of 100 nm and 100 °C were derived, respectively. Then the PCC wires with 100 nm palladium plating thickness were selected, and the bare copper wires were used as the reference, and multiple one-factor simulation experiments were carried out under the condition of changing the chip preheating temperature only. The simulation results show that the FAB and pad stress levels in the bonding results of the PCC wires are significantly higher than those of the bare copper wires, but the GaN layer stress is less than that of the bare copper wires. Moreover, there is an approximate parabolic relationship between the maximum stresses of pad and GaN layer and the preheating temperature of the chip. In the bonding results of bare copper wire, there is also an approximate parabolic relationship between the maximum stress of FAB and the chip preheating temperature. This parabolic relationship allows a prediction of the optimum chip preheating temperature. Selecting the appropriate palladium plating thickness and controlling the appropriate FAB temperature and chip preheating temperature can improve the bonding quality, and this numerical simulation work can provide a reference for the selection of palladium plating thickness and temperature parameter regulation of PCC wires.

Behavior of Extended Single-Plate Shear Connections Subjected to Combined Shear and Compression Forces Using Finite Element Analysis

Extended single-plate shear connections can be subjected to compression loads in addition to shear loads during extreme events like wind and earthquakes. However, the existing interaction equations found in the AISC Steel Construction Manual, in literature, and in design examples—which are being used in design for combined loading cases—have not been formally validated for use by experimental testing or finite element analysis. This research aims to study the behavior of these connections when subjected to combined loading of shear and compression force by performing a nonlinear finite element analysis in ABAQUS. The variables considered in the study are column web stiffness, connection configurations, and different bracing conditions of the beam. The results from these analyses were compared to the available interaction equations in the AISC Manual and in literature to assess their applicability under different conditions. Shear-compression interaction plots were generated from the results that show the shear strength decreases with an increase in compression force in the connection. The effect of the compression force on the shear strength depends on the column web’s rigidity and the bracing condition of the beam.

A semi-analytical approach for dynamic responses of monopile-supported offshore wind turbines subjected to accidental loads

Offshore wind energy is leading the way in sustainable energy generation. Offshore wind turbines (OWTs) need to be designed to withstand extreme or accidental loads in Ultimate Limit States (ULS) and Accidental Limit States (ALS), whereby high order eigenmodes may become significant. This paper introduces a semi-analytical approach for efficient and reliable analysis of the dynamic responses of monopile-supported OWTs subjected to accidental loads. A Rayleigh-Ritz solution is initially adopted to determine the high-order natural frequencies and eigenmodes of monopile OWTs, explicitly considering tapered towers and soil-pile interactions. Dynamic responses of OWTs are then calculated depending on the interaction schemes between accidental loads and the structures, e.g. soft contact loads (e.g. slamming, wind) and hard contact loads (e.g. ship collisions, ice impact). For soft contact loading conditions, the loads are considered independent of turbine responses, and the transient dynamic response is computed using the classical modal superposition method. While for hard contact loading conditions, the load actions depend on the contact stiffnesses and responses of the interacting bodies. A numerical contact algorithm is thus developed, and numerical iterations are performed to ensure convergence. The proposed approach is applied to the DTU 10 MW monopile-supported OWT subjected to extreme water slamming and ship collisions, respectively as example applications of soft and hard contact scenarios. The results are verified against nonlinear finite element analysis using USFOS and discussed with respect to the turbine natural frequencies and eigenmodes, contact forces and dynamic responses. A parametric analysis is conducted for ship-OWT collisions, exploring different impact scenarios by varying ship sizes, contact stiffnesses, and initial impact velocities. The proposed approach can serve as a promising tool for accidental load response analysis and the design of monopile OWTs.

Improved GAN-based deep learning approach for strain field prediction and failure analysis of precast bridge slab joints

Nonlinear finite element analysis (FEA) is crucial for understanding complex stress-strain behaviors and assessing potential structural failure risks. Building on the recent success of deep learning (DL) methods in physical field predictions, there has been growing interest in forecasting internal force fields of structures beyond the existing data scope. In this study, a data-driven strain field analysis model based on an improved Generative Adversarial Network (GAN) is proposed. To enrich the input data, this novel approach incorporates the Signed Distance Field (SDF) derived from the characteristics of the original Finite Element (FE) models. The generator, based on U-Net, is enhanced with channel attention mechanisms and loss penalty terms, forming the core of the improved GAN. The effectiveness of the proposed method is demonstrated using two parallel datasets comprising 3-Headed bar tension models across two planes. Subsequently, the generated strain field is subjected to feature extraction using the 2D-Principal Component Analysis (2D-PCA) method, followed by structural failure determination through the K-Nearest Neighbor (KNN) algorithm. The results indicate that the proposed improved approach achieves a significant reduction in Root Mean Square Error (RMSE) of 20.71 % and 13.21 % across the two datasets, with the structural failure determination method reaching an F1-score of 0.971. Thus, the intelligent strain field analysis method introduced here effectively predicts strain distributions and promptly identifies failure states, offering valuable insights for further numerical analysis and structural design.

The Change of Sealing Property in the Aging Process of NBR Sealing Equipment Based on Finite Element Analysis

Sealing rings are the core components of flange sealing structures and play a crucial role in the storage and operation of gas generators. The aging and deformation of seals affect the safe operation of the device. This paper aims to investigate the effect of rubber aging on the sealing performance of the components, which is realized by nonlinear finite element analysis. Firstly, an accelerated degradation test method was used to obtain the compression permanent deformation and stress–strain curve of rubber during the aging process. A two-dimensional finite element model of the sealing structure was constructed and the Yeoh model was utilized to describe the mechanical response of rubber. During the simulation, the contact area was modified based on the compression permanent deformation, and the Yeoh model was updated based on the stress–strain curve changes obtained by the test. The impact of key parameters such as material property changes, rubber physical section deformation, and fluid pressure on sealing performance during the seal ring aging process was systematically studied. The numerical results indicate that due to the aging deformation of rubber seals, there is a significant decrease in contact stress and contact width, as well as a shift in maximum equivalent stress area. Taking into account these findings, this study proposes a new design concept for sealing structures. This provides a relatively simple research method for studying flange sealing structure performance.

Static analysis using flexibility disassembly perturbation for material nonlinear problem with uncertainty

Nonlinear finite element analysis of large-scale structures usually requires a lot of calculation cost, because it is necessary to repeatedly inverse the modified stiffness matrix caused by nonlinearity in the calculation process. When considering the uncertainty in materials, the calculation of the nonlinear analysis will be more unbearable. To improve the computational efficiency, this work develops a new method for nonlinear analysis with material uncertainty based on flexibility disassembly perturbation (FDP) approach. The FDP is an algorithm that can quickly calculate the inverse of a stiffness matrix. The basic idea of the proposed method is to introduce the FDP formula into Newton-Raphson iteration method to accelerate the nonlinear iterative calculation. Three numerical examples, one statically determinate structure and two statically indeterminate structures, are used to verify the accuracy and efficiency of the proposed method. The results show that the calculation time of the proposed method is far less than that of the existing complete analysis and combined approximation algorithms. In terms of computational accuracy, for statically determinate structures, the proposed algorithm can obtain exact solutions that are identical to the complete analysis results, while for statically indeterminate structures, the proposed algorithm can obtain approximate solutions that are very close to the complete analysis results.

Contribution of geometrical infill pattern on mechanical behaviour of 3D manufactured polylactic acid specimen: Experimental and numerical analysis

Additive manufacturing is regarded as a very efficient fabrication technique since it permits the manufacturing of any three-dimensional product. The present work determines the effect of various infill pattern on the mechanical properties in term of tensile strength, yield strength and hardness of poly-lactic acid (PLA) samples fabricated by fused deposition modeling method. The mechanical behaviour of the 3D-printed PLAs investigated using dog-bone specimens with six distinct infill patterns: line, triangle, tri-hexagon, cubic, octet, and gyroid. The mechanical characteristics were evaluated using the uniaxial tensile test and shore D type hardness tester. The strain and deformation criteria were employed to substantiate the ductile and brittle characteristics. The fractural surface morphology analyzed using the field emission scanning electron microscope. Nonlinear Finite Element Analysis (FEA) was employed to simulate the uniaxial tensile test and establish a Yeoh third order hyperelastic material model for the predictions of the stress-strain response. This model is chosen for its precise ability to predict the nonlinear stress-strain responses for significant deformation and is crucial in applications that involve high degrees of flexibility and elasticity, such as in tire modeling, polymer and elastomer analysis, sports equipment designing, 3D printed components etc. Results revealed that the cubic infill had a maximum tensile strength 32.648 ± 1.42 MPa and octet infill had a minimum tensile strength 22.373 ± 0.79 MPa. The majority of experimental data indicated a brittle behaviour for line-infilled, but triangular, trihexagonal, cubic, octet, and gyroid infill patterns demonstrated ductile behaviour. In comparison to other geometrical infills, cubic shown relatively superior mechanical responses. Consequently, the geometrical infill effect plays a significant role in finding the appropriate mechanical property for industrial applications. The developed material model possesses potential utility in non-linear FEA investigations pertaining to 3D printed PLA objects that are predicted to sustain tensile strength.

The Detailed Axial Compression Behavior of CFST Columns Infilled by Lightweight Concrete

The utilization of lightweight aggregate concrete (LWC) plays a major role in reducing the self-weight of CFST (concrete-filled steel tube) columns, which is reflected in the behavior of the structural system. This paper aims to investigate the characteristics of lightweight concrete-filled steel tubular (LWCFST) columns under an axial compressive load, using a total of (48) LWCFST column models. The simulated models were divided into four groups with different concrete compressive strength, length-to-diameter ratios (L/D), and diameter-to-thickness ratios (D/t). Four concrete compressive values were examined (30, 40, 50, and 60) MPa, three length-to-diameter ratios short (L/D = 3), medium (L/D = 6), and long (L/D = 9), and four diameter-to-thickness ratios (36, 31, 26, and 21). The method of nonlinear finite element analysis (NLFEA) was used to fulfill the objective of this study where results were presented as graphical plots between the compressive loading versus the axial and lateral strains along with the failure modes. In addition, the results were compared with the AISC360-16 and EC4 codes predictions to examine their applicability on the LWCFST columns where the AISC was overpredicted in most cases with higher percentages under lower (L/D) values, whereas the EC2 was underestimated in most cases with high percentages up to 28%, which become closer to the NLFEA predictions at higher (L/D) values. It has been revealed that the utilization of steel tubes significantly improves the LWCFST column’s mechanical performance, ductility, compressive strength, and toughness. Moreover, the structural behavior of the LWCFST columns and their associated failure modes was found to be highly affected by the geometrical properties of the CFST column (i.e., L/D ratio and D/t ratio) where specimens with small tube thickness show bad behavior. Finally, the utilization of high-strength concrete has a favorable performance compared to the utilization of thick steel tubes.

Influence of reinforcement reductions on the response of reinforced concrete half-joints

Reinforced concrete half-joints are susceptible to deterioration mechanisms primarily due to the leakage of surface water, often contaminated with chlorides from de-icing salts, through the expansion joint. Due to the joint geometric form, favourable conditions can be created inside the joint for the corrosion of steel reinforcement. To this end, seven reinforced concrete half-joints were tested to failure under three-point bending to investigate the effect of reinforcement reductions that simulate common deterioration scenarios arising from the corrosion of reinforcement. The results were then compared to the predictions of nonlinear finite element analyses and the strut-and-tie method. The results demonstrated that a reduction in the amount of reinforcement close to the re-entrant corner has major influence on the load-deflection response of reinforced concrete half-joints. The largest reductions in load-carrying capacity were obtained from the half-joints with a full removal of diagonal bars and a combined removal of diagonal and U-bars, both showing reductions in load capacity of more than 50 %. The failure mode in each case of simulated deterioration scenarios involved a shear failure at the nib, except one case which displayed a shear failure in the full depth section due to the reduced anchorage of the bottom reinforcement. Furthermore, it was shown that nonlinear finite element analyses provide accurate predictions of the load-deflection response and failure crack patterns. The strut-and-tie method was found to result in overly conservative predictions, with an average observed-to-predicted load ratio of 1.48 and a coefficient of variation (COV) of 10.2 %. This is considerably higher than an average load ratio of 1.05 and a COV of only 3.1 % obtained from the nonlinear finite element analyses.

Intergranular fracture, grain-boundary structure, and dislocation-density interactions in FCC bicrystals

A dislocation-density based crystalline plasticity (DCP) and nonlinear finite element (FE) analysis were used to predict, and fundamentally understand how and why fracture nucleation and propagation are related to the interrelated microstructural mechanisms of dislocation-density pileups, GB structure, orientation, and total and partial dislocation density interactions within and adjacent for a random low angle grain boundary (LAGB) and a random high angle GB (HAGB). The GB orientations and structures were obtained from micropillar experiments, such that LAGBs and the HAGBs can be accurately represented and used for the modeling predictions. The normal stress, density of pileups, and dislocation-density accumulation along and within the GB were higher for the low angle GB bicrystal. These interrelated phenomena delineate how fracture for high angle GBs nucleate and propagate at lower nominal strains than the lower angle GB bicrystal case. These predictions underscore how fundamental mechanisms can be identified and used to understand how failure nucleates and propagates for different GB structures and orientations.

Structural performance of hybrid reinforced concrete beams containing polyvinyl alcohol fibers under thermal loads

This study focused on the efficiency of concrete beams containing polyvinyl alcohol fibers (PVA) under thermal loads. The eighteen concrete beams were reinforced with hybrid bars or a combination of GFRP bars and steel reinforcement bars (hybrid scheme). The main experimental variables were the level of temperature (25o, 300o, and 600o C), PVA fiber volume (0 %, 0.50 %, and 1.0 %), and the flexural reinforcement bars. The experimental test results are discussed in terms of the first crack load, flexural capacity, and load-deflection curves. Moreover, the initial and post-crack stiffness, ductility factor, and failure modes are discussed. The test results demonstrated a significant increase in the capacity of PVA concrete beams reinforced with hybrid reinforcement bars. At a temperature of 300o C, the inclusion of 0.50 % and 1.0 % PVA ratios improved the flexural capacities by 11 % and 24 %, respectively. Furthermore, the addition of PVA fibers enhanced the toughness by 34 % and 67 %, respectively, when compared to normal concrete beams. The results also demonstrate that using PVA fibers prevents the spalling of concrete beams after exposure to elevated temperatures. At 600 °C, beams containing 0.50 % and 1.0 % PVA fibers exhibited flexural capacities that were 9 % and 6 % higher, respectively, compared to normal concrete beams. Additionally, the inclusion of PVA fibers increased the toughness by 27 % and 21 % for the respective fiber ratios. Finally, a nonlinear finite element analysis (NLFEA) simulation was performed to verify the experimental test results and supplement experiments by predicting the results that are difficult to accomplish through experiments. With an average ratio of 1.02 between experimental and NLFEA ultimate capacity, the numerical results were an exact match of the patterns observed in the experimental results.

Finite-element analysis of different fixation types after Enneking II + III pelvic tumor resection

The current primary treatment approach for malignant pelvic tumors involves hemipelvic prosthesis reconstruction following tumor resection. In cases of Enneking type II + III pelvic tumors, the prosthesis necessitates fixation to the remaining iliac bone. Prevailing methods for prosthesis fixation include the saddle prosthesis, ice cream prosthesis, modular hemipelvic prosthesis, and personalized prosthetics using three-dimensional printing. To prevent failure of hemipelvic arthroplasty protheses, a novel fixation method was designed and finite element analysis was conducted. In clinical cases, the third and fourth sacral screws broke, a phenomenon also observed in the results of finite element analysis. Based on the original surgical model, designs were created for auxiliary dorsal iliac, auxiliary iliac bottom, auxiliary sacral screw, and auxiliary pubic ramus fixation. A nonlinear quasi-static finite element analysis was then performed under the maximum load of the gait cycle, and the results indicated that assisted sacral dorsal fixation significantly reduces stress on the sacral screws and relative micromotion exceeding 28 μm. The fixation of the pubic ramus further increased the initial stability of the prosthesis and its interface osseointegration ability. Therefore, for hemipelvic prostheses, incorporating pubic ramus support and iliac back fixation is advisable, as it provides new options for the application of hemipelvic tumor prostheses.