Finite Element Model Of Joint Research Articles

Integration of Swin UNETR and statistical shape modeling for a semi-automated segmentation of the knee and biomechanical modeling of articular cartilage

Simulation studies, such as finite element (FE) modeling, provide insight into knee joint mechanics without patient involvement. Generic FE models mimic the biomechanical behavior of the tissue, but overlook variations in geometry, loading, and material properties of a population. Conversely, subject-specific models include these factors, resulting in enhanced predictive precision, but are laborious and time intensive. The present study aimed to enhance subject-specific knee joint FE modeling by incorporating a semi-automated segmentation algorithm using a 3D Swin UNETR for an initial segmentation of the femur and tibia, followed by a statistical shape model (SSM) adjustment to improve surface roughness and continuity. For comparison, a manual FE model was developed through manual segmentation (i.e., the de-facto standard approach). Both FE models were subjected to gait loading and the predicted mechanical response was compared. The semi-automated segmentation achieved a Dice similarity coefficient (DSC) of over 98% for both the femur and tibia. Hausdorff distance (mm) between the semi-automated and manual segmentation was 1.4 mm. The mechanical results (max principal stress and strain, fluid pressure, fibril strain, and contact area) showed no significant differences between the manual and semi-automated FE models, indicating the effectiveness of the proposed semi-automated segmentation in creating accurate knee joint FE models. We have made our semi-automated models publicly accessible to support and facilitate biomechanical modeling and medical image segmentation efforts (https://data.mendeley.com/datasets/k5hdc9cz7w/1).

The mechanical behaviour of a slip joint for an offshore wind turbine: First monitoring and modelling results

This study aims at shedding light on the mechanical behaviour of a prototype monopile–wind turbine tower connection, constituted by a slip joint. Selected examples of data set recorded during a long term monitoring campaign are illustrated and discussed. The data set encompass axial and hoop stresses measured over the slip joint area, relative displacements of the slip joint with respect to the monopile and acceleration levels recorded above the slip joint. In parallel, an ideal and simplified Finite Element model (FEM) of the slip joint is developed, in order to interpret the observed experimental data. Experiments first highlight the relevance of modelling the manufacturing imperfections of the overlapping steel sections. Subsequently, both experiments and FEM show that states of prestress need to be accounted for. Such prestress states first originate from the installation process, and subsequently from further loading events, triggering settlements of the slip joint. Finally, experiments and FEM showcase the force transfer mechanisms from the upper part to the lower part of the slip joint.

Structural performance of a novel combined nested bolted joint for aluminum alloy mega-latticed structures

A novel steel-aluminum joint system is first presented for aluminum alloy mega-latticed structures. This joint can be effectively applied to the connection of large-diameter tube members with complex spatial locations in space structures. The joint's finite element model is examined and validated, followed by a case study of one joint, including static analysis and an analysis of the bending moment-rotation curve. According to the moment-rotation curve, the joint is classified as a type of semi-rigid joint. Furthermore, the analysis considers key parameters that impact the joint's bending, axial, and torsional performance, such as the number of bolts per ring, the rings of bolts, and the thickness of the joint zone. Two simplified formulas for joint stiffness are proposed to evaluate the overall structural stability. Finally, a stability analysis of an aluminum alloy mega-latticed structure is conducted, incorporating this joint and the proposed simplified formulas. The ultimate load of the mega-latticed structure with the joints is found to be about 0.7 of that with ideal rigid joints with the same parameters. This paper presents a potential solution for appropriate connections in large-span aluminum alloy mega-lattice structures, thereby serving as a reference for the design of the joints in related space structures.

Design of a lightweight universal talus implant using topology optimization.

Total talus replacement is a promising alternative treatment for talus fractures complicated by avascular necrosis and collapse. This surgical option replaces the human talus bone with a customized talus implant and can maintain ankle joint functionality compared to traditional treatment (e.g., ankle fusion). However, the customized implant is costly and time-consuming due to its customized nature. To circumvent these drawbacks, universal talus implants were proposed. While they showed clinically satisfactory results, existing talus implants are heavier than biological talus bones as they are solid inside. This can lead to unequal weight between the implant and biological talus bone, and therefore leading to other complications. The reduction of the implants' weight without compromising its performance and congruency with surrounding bones is a potential solution. Therefore, this study aims to design a lightweight universal talus implant using topology optimization. This is done through establishing the loading and boundary conditions for three common foot postures: neutral, dorsi- and plantar-flexion. The optimized implant performance in terms of mass, contact characteristics with surrounding joint cartilage and stress distributions is studied using a 3D Finite Element (FE) model of the ankle joint. The mass of the optimized implant is reduced by approximately 66.6% and its maximum stresses do not exceed 70MPa, resulting in a safety factor of 15.7. Moreover, the optimized and solid implants show similar contact characteristics. Both implants produced peak contact pressures that were approximately 19.0%-196% higher than those produced by the biological talus. While further mechanical testing under in-vivo loading conditions is required to determine clinical feasibility, preliminarily, the use of a lightweight universal implant is expected to provide the patient with a more natural feel, and a reduced waiting period until surgery.

Stiffness Characteristics and Analytical Model of a Flange Joint with a Spigot

Flange joints with spigots are widely used in aero-engines. The spigot will restrict the shear slipping between flanges, which, in turn, affects the stiffness characteristics of the joint. The current model and research on flange joints without spigots may not be suitable for the dynamic characteristics of aero-engines. Moreover, the complexity of contact pairs limits the application of the flange joint finite element (FE) model in aero-engine dynamics analysis. Therefore, a simplified analytical model of a flange joint with a spigot is proposed in this paper. First, the stiffness characteristic of the flange joint with a spigot is studied using the FE method. Second, a corresponding experiment is executed to verify the result of the FE analysis. Furthermore, based on the former FE and experimental analysis, one section of a flange joint is simulated by the Jenkins friction model and a spring. Then, a simplified analytical model of the entire flange joint is built according to the different statuses of each section. Finally, a simulation analysis of the stiffness characteristic is performed. The result shows that the simplified analytical model can be utilized to describe the bending stiffness characteristic of the flange joint with a spigot.

Numerical simulation of plasticity in double lap metallic bolted joints

This article aims to compare three plasticity models, namely Bai-Wierzbicki (BW), von Mises and Drucker Prager, to predict the failure modes in double-lap metallic bolted joints under shear loading. The double-lap bolted joint finite element model has been validated against literature data, which demonstrated the application of BW ductile fracture model to bolt joint failure prediction. Taguchi Design is used to investigate the effects of geometrical parameters, preload and stress triaxiality on the failure modes. Force–displacement response amongst the three models differs up to 20% when failing in shear and a different prediction of the failure mode (shear out vs. net section) under the same loading and geometry conditions is observed.

Theoretical and experimental research on the joint control mechanism of the roll gap in large diameter ratio rolling mill

To adjust the roll gap shape in the large diameter ratio rolling mill, this paper proposes a new mechanism for controlling the roll gap of the large diameter ratio rolling mill, based on the principle of working roll bending technology (WRB) and roll profile electromagnetic control technology (RPECT). According to the principle of the mechanism, it can be called WRB-RPECT joint control mechanism. To analyze the roll gap shape control ability of this mechanism, a joint finite element model of the large diameter ratio roll system with the electromagnetic control roll (ECR) is established, and verified by the rolling experiment in the Y-type electromagnetic control rolling mill. Based on the finite element model, the loaded characteristic of the working rolls, the contact stress between rolls, the transverse thickness distribution of strip and the adjustment range of roll gap crown are analyzed for different rolling forces and different WRB-RPECT joint control mechanisms. The results show that the WRB-RPECT joint control mechanism has certain roll gap shape control ability of the large diameter ratio rolling, and can achieve the roll gap control goal of uniform transverse size distribution.

LibHip: An open-access hip joint model repository suitable for finite element method simulation

Background and objective: population-based finite element analysis of hip joints allows us to understand the effect of inter-subject variability on simulation results. Developing large subject-specific population models is challenging and requires extensive manual effort. Thus, the anatomical representations are often subjected to simplification. The discretized geometries do not guarantee conformity in shared interfaces, leading to complications in setting up simulations. Additionally, these models are not openly accessible, challenging reproducibility. Our work provides multiple subject-specific hip joint finite element models and a novel semi-automated modeling workflow.Methods: we reconstruct 11 healthy subject-specific models, including the sacrum, the paired pelvic bones, the paired proximal femurs, the paired hip joints, the paired sacroiliac joints, and the pubic symphysis. The bones are derived from CT scans, and the cartilages are generated from the bone geometries. We generate the whole complex’s volume mesh with conforming interfaces. Our models are evaluated using both mesh quality metrics and simulation experiments.Results: the geometry of all the models are inspected by our clinical expert and show high-quality discretization with accurate geometries. The simulations produce smooth stress patterns, and the variance among the subjects highlights the effect of inter-subject variability and asymmetry in the predicted results.Conclusions: our work is one of the largest model repositories with respect to the number of subjects and regions of interest in the hip joint area. Our detailed research data, including the clinical images, the segmentation label maps, the finite element models, and software tools, are openly accessible on GitHub and the link is provided in Moshfeghifar et al.(2022)[1]. Our aim is to empower clinical researchers to have free access to verified and reproducible models. In future work, we aim to add additional structures to our models.

Ligament mechanics of ageing and osteoarthritic human knees.

Knee joint ligaments provide stability to the joint by preventing excessive movement. There has been no systematic effort to study the effect of OA and ageing on the mechanical properties of the four major human knee ligaments. This study aims to collate data on the material properties of the anterior (ACL) and posterior (PCL) cruciate ligaments, medial (MCL) and lateral (LCL) collateral ligaments. Bone-ligament-bone specimens from twelve cadaveric human knee joints were extracted for this study. The cadaveric knee joints were previously collected to study ageing and OA on bone and cartilage material properties; therefore, combining our previous bone and cartilage data with the new ligament data from this study will facilitate subject-specific whole-joint modelling studies. The bone-ligament-bone specimens were tested under tensile loading to failure, determining material parameters including yield and ultimate (failure) stress and strain, secant modulus, tangent modulus, and stiffness. There were significant negative correlations between age and ACL yield stress (p = 0.03), ACL failure stress (p = 0.02), PCL secant (p = 0.02) and tangent (p = 0.02) modulus, and LCL stiffness (p = 0.046). Significant negative correlations were also found between OA grades and ACL yield stress (p = 0.02) and strain (p = 0.03), and LCL failure stress (p = 0.048). However, changes in age or OA grade did not show a statistically significant correlation with the MCL tensile parameters. Due to the small sample size, the combined effect of age and the presence of OA could not be statistically derived. This research is the first to report tensile properties of the four major human knee ligaments from a diverse demographic. When combined with our previous findings on bone and cartilage for the same twelve knee cadavers, the current ligament study supports the conceptualisation of OA as a whole-joint disease that impairs the integrity of many peri-articular tissues within the knee. The subject-specific data pool consisting of the material properties of the four major knee ligaments, subchondral and trabecular bones and articular cartilage will advance knee joint finite element models.

Analysis of Rotator Cuff Muscle Injury on the Drawing Side of the Recurve Bow: A Finite Element Method.

Background This study establishes the shoulder model on the drawing side of recurve archers by the finite element method and finds out the stress changes on the rotator cuff muscles in the position of the humerus and scapula under different stages of special techniques. The aim of this study is to investigate the mechanism of rotator cuff damage on a recurve archer's drawing arm. Methods A 22-year-old healthy male's shoulder CT and MRI data were collected, and the drawing side shoulder joint finite element model was constructed, which contains the structure of the shoulder blades, clavicle, humerus, supraspinatus, infraspinatus, teres minor, and subscapularis. The humerus on the drawing arm was simulated to raising the bow, drawing, holding, and releasing on the scapula plane, and stress changes in rotator cuff muscles are analyzed. Results The peak stress on the infraspinatus increased slowly, and from the start of raising the bow to hold and release, the stress peak increased from 0.007 MPa to 0.009 MPa. The peak stress on teres minor rises slowly from 0.003 MPa at the start of raising the bow to 0.010 MPa at the moment of releasing. The peak stress in the subscapularis increased from 0.096 MPa to 0.163 MPa between the start of raising the bow and releasing. The peak stress on the supraspinatus varied greatly, and from the start of raising the bow to the start of drawing, the stress peak increased markedly from 1.159 MPa to 1.395 MPa. Subsequently, the stress peak immediately decreased to 1.257 MPa at the start of holding and then increased to 1.532 MPa at releasing. Conclusion The position of the humerus and scapula would change with the different stages of special techniques. It causes stress changes in the rotator cuff muscles, and when the stress accumulates over time, the shoulder 5on the drawing side will gradually become injured and dysfunctional. In combination with the depth of the structural site and the surrounding structural features, corrective exercises can be used to prevent injury to the rotator cuff muscles.

Numerical analysis on seismic behavior of beam-column joint with different cement-based materials

Under cyclic loading conditions, the ductility of frame beam-column joints, which can be evaluated by the displacement ductility coefficient ( μ), is strongly affected by the axial load ratio ( n). Due to the high toughness of engineering cementitious composites (ECCs), the normal concrete can be replaced giving better joint ductility. However, the limit values of n for reinforced ECC (R-ECC) joints have not been clarified. Therefore, T- and cross-shaped reinforced concrete (RC) and R-ECC joint finite element models were established and analyzed under n values. The results indicated that the seismic performance of the joints, including μ, equivalent damping coefficient ( ξ eq), and secant stiffness ( K i) were strongly dependent on n. μ and ξ eq became inversely proportional to n when n was over 0.5. The RC and R-ECC joint ductile failure could occur when n was in the range of 0.3–0.7 and 0.3–0.9, respectively. The joint brittle failure occurred in RC and R-ECC joints when n was over 0.7 and 0.9, separately. Under the same n and load history, the maximum value of μ of R-ECC joints increased by 33.7% and 27.9% for T- and cross-shaped joints separately compared to that of RC joints. It is suggested that the n values for RC and R-ECC joints should not exceed 0.7 and 0.9, respectively.

Design of adhesive-bonded structure solutions, contribution of the modelling of the adhesive

Finite element modelling of adhesive joints has been analysed in this work, applying the results and conclusions of the design process of a multi-material base of an elevator. The main approach of the study has been the modelling of the adhesive joint, different parameters and its application in complex models. For that purpose, a case study has been carried out in a simply supported plate model. Several modelling techniques have been analysed and design recommendations have been proposed. Characterization of composite materials and adhesives has also been studied, given the fact that the anisotropy of the composites is an additional difficulty in the Finite Element Analysis. Having the real properties of these materials is a very important factor for efectiveness in terms of economical and computational cost. The correlation of simulation and experimental results has been analysed in the practical case study and the contribution of the adhesive modelling has been studied. To conclude, the importance of the material characterization and the sensitiveness to the variation of their properties are to be mentioned. The work offers the designer several recommendations on adhesive joint modelling as well as parameters that might affect the analysis of a structure that contains adhesive bonding.

Study of Damage to the Drawing Arm Subacromial Bursa in Recurve Archers Based on a Finite Element Model

Background: The purpose of this study was to simulate the drawing arm of male recurve archers by finite element method. And observe the stress changes of humerus and scapula on the subacromial bursa under different stages of special techniques. To investigate the mechanism of the subacromial bursa injury in male recurve archers. Methods: Collected a 22-year-old healthy men shoulder CT and MRI data, construct the bow side shoulder joint finite element model, contains the structure of the shoulder blades, clavicle, humerus, and subacromial bursa. The humerus on the drawing side of the curve was simulated to perform the raising the bow, drawing, holding and releasing actions on the scapula plane, analysis of stress changes in subacromial bursa. Results: The peak stress on the subacromial bursa varied greatly. From the start of raising the bow to the start of drawing, the stress peak decreased markedly from 0.280 MPa to 0.036 MPa. Then, the peak stress immediately increased to 0.347 MPa at the beginning of the holding and decreased to 0.262 MPa at releasing. Conclusions: The reason for the stress surge on the subacromial bursa in the holding phase is that its structure is easily squeezed by multiple surrounding tissue structures, resulting in high stress and susceptibility to damage. In combination with the depth of the structural site and the surrounding structural characteristics, this can prevent subacromial bursa injury. The results of this work are particularly relevant to the prevention of subacromial bursa injury in male recurve archers.

Experimental and finite element analysis of modular prefabricated composite beam-column interior joints

This contribution presents quasi-static tests of three modular prefabricated composite beam-column interior joints (MPCIJs), analyzing the strain distribution, ductility, energy consumption, strength, and stiffness degradation . Three finite element models were established by ABAQUS and compared with quasi-static test results to verify their correctness. The stress mechanism of different materials in MPCIJs was further analyzed. Results showed that the absolute value of the plastic drift ratio was 6.41–8.01% rad, the ductility coefficient was 3.50–4.50, and the equivalent viscous damping coefficient was 0.32–0.33. The overall degradation performance of MPCIJs strength and stiffness were relatively stable. MPCIJs achieved good seismic performance and large rotational deformation capacity. The stress (strain) in the joint module, consistent with the ‘diagonal compression bar’, was diagonally distributed. The high-stress connection bolt at the column end is located on both sides of the centerline along the direction of the beam length. The internal stress of concrete follows an antisymmetric distribution along the diagonal direction and diffuses outward at an angle of 45°. • A new type of modular composite joint is proposed. • Physical tests and finite element analysis of composite joints are carried out. • Verify the correctness of the modular composite joint finite element model. • The stress mechanism of joints with different composition materials is clarified. • The modular composite joint meets the requirements of seismic fortification.

Axial stiffness of concrete filled rectangular steel tubular (CFRST) truss joints

The flexural stiffness of the truss is affected by the joint stiffness. Due to the infilled concrete, the axial stiffness of the concrete filled rectangular steel tubular (CFRST) truss joints is different with the brace under tension and compression. In order to study the axial stiffness of the CFRST joints, the calculating models were developed by employing the component method. The validated finite element (FE) method was proposed to build FE models of joints. Parametric analysis of the inclined angle θ of the brace and the gap g of K joints was performed. Nonlinear fitting of the undetermined factors of stiffness equations was conducted based on FE results. Consequently, calculating equations of the axial stiffness of CFRST T, Y and K joints were adopted to predict the flexural stiffness of CFRST trusses. Results indicated that the predicted flexural stiffness of the truss coincided well with the tested results. The effect of the joint on the flexural stiffness of the truss was well considered.

Finite element model validation based on an experimental model of the intact shoulder joint

The shoulder joint is a complex anatomical system. The main goal of this study was to build a Finite Element (FE) model of the intact shoulder joint and its validation was done using an experimental model comparing cortical strains. Considering the expected differences between the experimental model and an in vivo shoulder, the experimental model developed replicates adequately the in vivo functioning of the joint.For the experimental model we used 4th generation composite bone structures of the humerus and scapula, including the humeral head cartilage, the glenoid cartilage and glenohumeral ligaments. The model also comprises the most important muscles in abduction. The FE model of the intact shoulder was developed mimicking the experimental model regarding the geometry of the bone structures.Strain gage rosettes were used to measure strain responses loading bone structures positioned in a 90° abduction angle. The accuracy of the strains calculated (numerical model) and measured (experimental model) was evaluated with linear regression analysis. The correlation coefficient of 0.76 and RMSE of 107 µε indicate an adequate agreement between numerical and experimental strains.The experimental procedure to simulate the biomechanics of the intact shoulder joint is a difficult task due to the instability of the joint and the number of structures that compose it. The use of FE models is necessary to perform more complex biomechanical studies, which are normally impossible to make with experimental ones, highlighting the importance of validation of FE models. The results of these models can then be used to compare with clinical data considering, however, the inherent characteristics of numerical simulations and differences relatively to clinical models.

Characterization of Adhesives Bonding in Aircraft Structures.

Structural adhesives play an important role in aerospace manufacturing, since they provide fewer points of stress concentration compared to faster joints. The importance of adhesives in aerospace is increasing significantly because composites are being adopted to reduce weight and manufacturing costs. Furthermore, adhesive joints are also studied to determine the crashworthiness of airframe structure, where the main task for the adhesive is not to dissipate the impact energy, but to keep joint integrity so that the impact energy can be consumed by plastic work. Starting from an extensive campaign of experimental tests, a finite element model and a methodology are implemented to develop an accurate adhesive model in a single lap shear configuration. A single lap joint finite element model is built by MSC Apex, defining two specimens of composite material connected to each other by means of an adhesive; by the Digimat multi-scale modeling solution, the composite material is treated; and finally, by MSC’s Marc, the adhesive material is characterized as a cohesive applying the Cohesive Zone Modeling theory. The objective was to determine an appropriate methodology to predict interlaminar crack growth in composite laminates, defining the mixed mode traction separation law variability in function of the cohesive energy (Gc), the ratio between the shear strength τ and the tensile strength σ (), and the critical opening displacement υc.

Comparisons of finite element models used to predict bending strength of mortise-and-tenon joints

This study aimed to obtain a better method for establishing a finite element model of mortise-and-tenon (M-T) joints. Three types of M-T joint finite element models, which included a whole rigid model, a tie rigid model, and a semi-rigid model, were established and compared with experimental results by predicting the bending moment capacity (BMC) of M-T joints based on the finite element method (FEM). The results showed that the semi-rigid model performed much better than the tie rigid model, followed by the whole rigid model. For the semi-rigid model, the ratios of FEM ranged from 0.85 to 1.09. For the whole rigid model and tie rigid model, the BMC of the M-T joint was overestimated. In addition, the results showed that tenon size remarkably affected the BMC and stiffness of the M-T joint, and tenon width had a greater effect on the BMC of the M-T joint than the tenon length.

Construction and simulation mechanical analysis of dynamic knee joint finite element model based on CT image

To construct a dynamic knee joint finite element model based on CT image data and verify the validity of the model. To provide a simulation model and basic data for biomechanical research of the knee joint by further finite element analysis. The CT data of a healthy male knee joint was selected. With the help of Mimics 19.0 and Hypermesh 12.0 software, a high simulation finite element model of knee joint was established following steps, including geometric reconstruction, reverse engineering, meshing and material characterization. The dynamic knee flexion model was generated by determining the boundary conditions and torque loading, and the validity of themodel was confirmed. The biomechanical changes of the tibiofemoral and patellofemoral joints under different knee flexion angles were analyzed by applying the loads (500 N) to the finite element model during knee flexion. A finite element model of knee joint was established based on CT images and anatomical characteristics. The model included three-dimensional elements such as bone, ligament, cartilage, meniscus and patellar retinaculum. The different finite element models of knee flexion states were produced by applying different torques after establishing boundary conditions. According to equivalent conditions (knee flexion 30 degrees, quadriceps tendon under 200 N stretch), the peak stress value of patella was 2.209 MPa and the average Mises stress was 1.132 MPa; the peak stress value of femoral trochlear was 1.405 MPa and the average Mises stress was 0.936 MPa. The validity of the model was proved by the difference between the model and previous studies of 1% to 13.5%. Dynamic model loading showed that the Mises stressof tibiofemoral joint decreased with the increase of knee flexion angle, while the Mises stress of patellofemoral joint was positively correlated with knee flexion angle. The Mises stress of cartilage stress planes at different knee flexion angles was significantly different(P<0.05). The finite element model established in this study is more comprehensive and can effectively simulate the biomechanical characteristics of dynamic knee joint, which provides support for further simulation mechanics researches of the knee joint.

EMG-Assisted Muscle Force Driven Finite Element Model of the Knee Joint with Fibril-Reinforced Poroelastic Cartilages and Menisci

Abnormal mechanical loading is essential in the onset and progression of knee osteoarthritis. Combined musculoskeletal (MS) and finite element (FE) modeling is a typical method to estimate load distribution and tissue responses in the knee joint. However, earlier combined models mostly utilize static-optimization based MS models and muscle force driven FE models typically use elastic materials for soft tissues or analyze specific time points of gait. Therefore, here we develop an electromyography-assisted muscle force driven FE model with fibril-reinforced poro(visco)elastic cartilages and menisci to analyze knee joint loading during the stance phase of gait. Moreover, since ligament pre-strains are one of the important uncertainties in joint modeling, we conducted a sensitivity analysis on the pre-strains of anterior and posterior cruciate ligaments (ACL and PCL) as well as medial and lateral collateral ligaments (MCL and LCL). The model produced kinematics and kinetics consistent with previous experimental data. Joint contact forces and contact areas were highly sensitive to ACL and PCL pre-strains, while those changed less cartilage stresses, fibril strains, and fluid pressures. The presented workflow could be used in a wide range of applications related to the aetiology of cartilage degeneration, optimization of rehabilitation exercises, and simulation of knee surgeries.