Three-dimensional Force Research Articles

A Three-Dimensional Body Force Modeling of Fans in Windmilling Condition and Its Application

To investigate the aerodynamic characteristics of the fan in windmilling conditions, a new body force model with the fan rotational speed prediction model was developed. The fan rotational speed prediction model was built based on the balance of fan output torque and resistance torque. The rotational speed of the fan spool can be iteratively solved simultaneously with solving the governing equations without requiring mass flow rate or other inputs. The comparison with the experimental results shows that using the body force model can accurately predict the rotational speed of the fan spool under different operating conditions. The radial distribution of flow parameters can be obtained. Moreover, numerical simulations of the fan under different circumferential total pressure distortion inflow conditions were conducted using the body force model. The results show that, unlike the design point and non-design point at which the fan operates normally, the high radius region of the fan is in the “turbine mode” while the low radius region is in the “compressor mode” under windmilling conditions. The different effects on the longitudinal vortex in the two regions deepen and alleviate the circumferential distortion, respectively. There are strong circumferential and radial pressure gradients at the junction of the distortion-affected zone and the non-distortion-affected zone, adding additional mixing losses.

A THREE-DIMENSIONAL TIRE REF MODEL IN ROLLING CONTACT WITH APPLICATION TO INTELLIGENT TIRES

ABSTRACT A new three-dimensional tire REF (ring on elastic foundation) model in rolling contact has been proposed and verified in this paper. The motivation is to apply this new physical model to the three-dimensional forces estimation for intelligent tires, which is currently a research hotspot in the automotive industry. The core contribution is the analytical solution of the three-dimensional tire deformation, stress, and forces in complex rolling contact. This new physical model is universal and efficient in linking intelligent tire signals with the solution results, which provides a powerful theoretical tool for intelligent tire modeling. Furthermore, the results have been validated by sensitivity analysis of key structural parameters on tire performance. In summary, through the modeling, verification, and application in case studies, it has been shown that the proposed methodology can be used for real practical three-dimensional forces estimation, which has the potential to simplify the vehicle state observer and benefit autonomous vehicles.

Shallow stability of soil slope with frame protection considering rainwater seepage: A calculation method

This paper introduces an integrated calculation method for analyzing the impact of frame protection engineering on the safety factor of shallow stability for soil slopes. The calculation method is based on the infinite long slope model, but it produces superior results by comprehensively taking into account the anti-sliding effect of the shallow slope sliding body. It combines the tension zone at the upper edge, the main sliding zone in the middle section, and the compression zone at the lower edge, while considering the anti-sliding force system of the frame protection structure and its contact surface with the soil. By converting the three-dimensional force system into a two-dimensional plane problem, an approximate calculation method for the shallow stability analysis of soil slopes with frame protection under rainfall seepage was established and numerically verified using the finite element method. The analysis indicates that the safety factor of the slope decreases significantly when seepage force is considered. As the length of the main sliding zone increases, the safety factor gradually decreases and approaches the result of the infinite long slope model. When the length decreases to zero, the safety factor gradually increases and approaches the result of the circular slip model. The use of frame protection significantly improves slope stability under rainfall seepage, and the safety factor increases with the number and embedded depth of the frame structure.

Analysis of technical characteristics of typical lower limb balance movements in Tai Chi: a cross-sectional study based on AnyBody bone muscle modeling.

Tai Chi is an excellent traditional Chinese physical fitness exercise, and its unique balancing movements are very important for improving human balance. In this study, the two most representative Tai Chi balance movements, "knee lift balance" and "leg stirrup balance", were selected to establish the lower limb bone muscle model of Tai Chi balance movements by using computer simulation modeling technology, aiming to analyze the characteristics of the lower limb movement mechanisms of typical balance movements, to provide a quantitative theoretical basis for improving the scientific level of Tai Chi. A total of 16 subjects were recruited for this study. the BTS three-dimensional motion capture system and three-dimensional force platform were used for motion data acquisition, the physiological electromyographic signals were collected using BTS surface electromyography, and the lower limb bone muscle model of Tai Chi balance movements was established by AnyBody human simulation. In the knee lift balancing movement, the balance leg hip abduction/adduction angle, hip flexion/extension moment, and the strength of the rectus femoris muscle, biceps femoris short capitis, and iliacus muscle of the amateur group was significantly smaller than that of the professional group (P<0.01). In the leg stirrup balance movement, the knee flexion/extension angle of the balancing leg in the amateur group was significantly greater than that in the professional group (P<0.01), and the hip flexion/extension angle, hip inversion/abduction angle, knee flexion/extension moment, hip flexion/extension moment, the strength iliacus, gluteus maximus, and obturator internus were significantly smaller than those in the professional group (P<0.01). The integral EMG of the biceps femoris of the support leg in the amateur group was significantly smaller than that of the professional group (P<0.01). The integral EMG of the lateral femoral muscle of the balance leg was significantly smaller than that of the professional group (P<0.01). In this study, we found that the balancing leg of the balancing movement has a larger hip joint angle, the stirrup balancing knee joint angle is smaller, and the hip and knee joint moments are larger. This is related to joint activity and muscle activation, and amateurs should pay attention to increasing the range of motion of the hip joint and decreasing the range of motion of the knee joint when practicing to better stimulate exercise of the lower limb joints. In addition, the practice of balancing movements should strengthen the iliacus muscle, which plays an important role in maintaining the stable balance of the lower limbs, and strengthen the knee flexor and extensor muscles and hip adductor/abductor muscles of the balancing leg, thus promoting the stability of the balancing leg movements.

2.5D Traction Force Microscopy: Imaging three-dimensional cell forces at interfaces and biological applications.

The forces that cells, tissues, and organisms exert on the surface of a soft substrate can be measured using Traction Force Microscopy (TFM), an important and well-established technique in Mechanobiology. The usual TFM technique (two-dimensional, 2D TFM) treats only the in-plane component of the traction forces and omits the out-of-plane forces at the substrate interfaces (2.5D) that turn out to be important in many biological processes such as tissue migration and tumour invasion. Here, we review the imaging, material, and analytical tools to perform "2.5D TFM" and explain how they are different from 2D TFM. Challenges in 2.5D TFM arise primarily from the need to work with a lower imaging resolution in the z-direction, track fiducial markers in three-dimensions, and reliably and efficiently reconstruct mechanical stress from substrate deformation fields. We also discuss how 2.5D TFM can be used to image, map, and understand the complete force vectors in various important biological events of various length-scales happening at two-dimensional interfaces, including focal adhesions forces, cell diapedesis across tissue monolayers, the formation of three-dimensional tissue structures, and the locomotion of large multicellular organisms. We close with future perspectives including the use of new materials, imaging and machine learning techniques to continuously improve the 2.5D TFM in terms of imaging resolution, speed, and faithfulness of the force reconstruction procedure.

FR3D: Three-dimensional flow reconstruction and force estimation for unsteady flows around extruded bluff bodies via conformal mapping aided convolutional autoencoders

In many practical fluid dynamics experiments, measuring variables such as velocity and pressure is possible only at a limited number of sensor locations, for a few two-dimensional planes, or for a small 3D domain in the flow. However, knowledge of the full fields is necessary to understand the dynamics of many flows. Deep learning reconstruction of full flow fields from sparse measurements has recently garnered significant research interest, as a way of overcoming this limitation. This task is referred to as the flow reconstruction (FR) task. In the present study, we propose a convolutional autoencoder based neural network model, dubbed FR3D, which enables FR to be carried out for three-dimensional flows around extruded 3D objects with different cross-sections. An innovative mapping approach, whereby multiple fluid domains are mapped to an annulus, enables FR3D to generalize its performance to objects not encountered during training. We conclusively demonstrate this generalization capability using a dataset composed of 80 training and 20 testing geometries, all randomly generated. We show that the FR3D model reconstructs pressure and velocity components with a few percentage points of error. Additionally, using these predictions, we accurately estimate the Q-criterion fields as well lift and drag forces on the geometries.

Measurement of the Three-Dimensional Muscle Endpoint Forces in the Extended Thumb and Its Application to Determining Muscle Combinations that Enable Lateral Pinch Force Production Throughout the Plane of Flexion-Extension.

Functional outcomes of tendon transfer surgeries, designed to restore lateral pinch grasp to persons following cervical spinal cord injury, have been mixed. That is, pinch force magnitudes have varied by 10-fold and have been reported to be as low as low as tenths of a pound. We believe a novel tendon transfer approach in which the donor muscle actuates a small group of paralyzed thumb muscles, instead of just the flexor pollicis longus (FPL) muscle (the current approach), will enable endpoint forces that are better directed and therefore a consistently stronger pinch force following surgery. We further believe that such surgeries can be better designed to account for grasp force production throughout the entire plane of flexion-extension if muscle endpoint forces in the extended thumb are known. Consequently, we measured muscle endpoint forces in the extended thumb in 6 cadaveric specimens after a force of 10 N was applied to each muscle. Further, we simulated a tendon transfer surgery in which the donor muscle applied equal force to each muscle in 246 small groups of muscles, calculated the direction of the resulting endpoint force throughout the flexion-extension plane, and determined if those groups of muscles produced a better directed force than FPL's. While we found that 3 individual muscles and 52 muscle groups could produce desirably directed endpoint forces in parts of the flexion-extension plane, no muscle or muscle group could produce well-directed endpoint forces throughout the flexion-extension plane. We concluded that a group of muscles could likely be found if the donor muscle provided different levels of force to each of the muscles in a muscle group. This would be possible through intentional geometric manipulation of the donor-to-recipient muscle attachment to allow for unequal splitting of donor muscle force.Clinical Relevance-This work aims to determine whether the same combination of thumb muscles can produce well-directed endpoint forces throughout the flexion-extension plane. If so, then this work informs surgeons which muscle groups could be involved in a tendon transfer to restore lateral pinch grasp ability throughout the plane of flexion-extension in person with cervical spinal cord injury.

Legolas 2.0: Improvements and extensions to an MHD spectroscopic framework

We report on recent extensions and improvements to the Legolas code, which is an open-source, finite element-based numerical framework to solve the linearised (magneto)hydrodynamic equations for a three-dimensional force- and thermally balanced state with a nontrivial one-dimensional variation. The standard Fourier modes imposed give rise to a complex, generalised non-Hermitian eigenvalue problem which is solved to quantify all linear wave modes of the given system in either Cartesian or cylindrical geometries. The framework now supports subsystems of the eight linearised MHD equations, allowing for pure hydrodynamic setups, only one-dimensional density/temperature/velocity variations, or the option to treat specific closure relations. We discuss optimisations to the internal datastructure and eigenvalue solvers, showing a considerable performance increase in both execution time and memory usage. Additionally the code now has the capability to fully visualise eigenfunctions associated with given wave modes in multiple dimensions, which we apply to standard Kelvin-Helmholtz and Rayleigh-Taylor instabilities in hydrodynamics, thereby providing convincing links between linear stability analysis and the onset of non-linear phenomena.

Devices to measure calf raise test outcomes: A narrative review.

The calf raise test (CRT) is commonly administered without a device in clinics to measure triceps surae muscle function. To standardise and objectively quantify outcomes, researchers use research-grade or customised CRT devices. To incorporate evidence-based practice and apply testing devices effectively in clinics, it is essential to understand their design, applicability, psychometric properties, strengths, and limitations. Therefore, this review identifies, summarises, and critically appraises the CRT devices used in science. Four electronic databases were searched in April 2022. Studies that used devices to measure unilateral CRT outcomes (i.e., number of repetitions, work, height) were included. Thirty-five studies met inclusion, from which seven CRT devices were identified. Linear encoder (n=18) was the most commonly used device, followed by laboratory equipment (n=6) (three-dimensional motion capture and force plate). These measured the three CRT outcomes. Other devices used were electrogoniometer, Häggmark and Liedberg light beam device, Ankle Measure for Endurance and Strength (AMES), Haberometer, and custom-made. Devices were mostly used in healthy populations or Achilles tendon pathologies. AMES, Haberometer, and custom-made devices were the most clinician-friendly, but only quantified repetitions were completed. In late 2022, a computer vision mobile application appeared in the literature and offered clinicians a low-cost, research-grade alternative. This review details seven devices used to measure CRT outcomes. The linear encoder is the most common in research and quantifies all three CRT outcomes. Recent advances in computer-vision provide a low-cost research-grade alternative to clinicians and researchers via a n iOS mobile application.

Decoupling control of three-dimensional electromagnetic forces in linear induction motors based on novel equivalent circuit

Since the single-sided linear induction motor not only produces thrust, but also produces vertical and transversal forces, if no specific control is applied, vertical and transversal forces can have a negative effect on the load propelled by the motor, especially in the application of the railway transit. Therefore, the best solution to the above issues is to independently control the vertical force or transversal force without changing the thrust in the motor. First, this paper presents a 3-D electromagnetic forces, i.e. thrust, vertical and transversal forces, decoupling strategy for the single-sided linear induction motor based on a novel equivalent circuit considering the longitudinal end effect and 3-D electromagnetic forces. Then, the slip-frequency calculator, thrust observer and thrust controller in the conventional vector control for induction motors are reconstructed, and a force decoupling controller is proposed. Finally, the simulation to verify the vector control with the force decoupling controller for the linear motor is performed by using a prototype motor which is used for railway transit.

Triceps surae muscle forces during dynamic exercises in patients with Achilles tendinopathy: A cross-sectional study.

The aim of this study was to investigate the individual triceps surae muscle forces during the execution of six different functional movements and rehabilitation exercises in patients with Achilles tendinopathy compared to a control group. Triceps surae muscle forces of 15 participants with Achilles tendinopathy (AT) and 15 healthy controls were estimated through a combination of experimental data and musculo-skeletal modeling. Three-dimensional motion capture and force plates were used to collect the ankle and knee joint angles and moments during three functional movements (walking, heel walking, and toe walking) and three rehabilitation exercises (bilateral heel drop, unilateral heel drop with extended knee and with flexed knee). A dynamic optimization method was used to obtain the modeled triceps surae muscle forces. Force-sharing strategies were calculated at the peak triceps surae muscle force and compared between groups. Lower peak triceps surae forces were obtained for the AT group during dynamic exercises. Across all exercises, the average contribution of the soleus (SOL) to the total triceps surae muscle force was the largest (60.83 ± 13.89% [AT] > 56.90 ± 16.18% [healthy]), followed by the gastrocnemius medialis (29.87 ± 10.67% [AT] < 32.19 ± 12.90% [healthy]) and the gastrocnemius lateralis (9.30 ± 4.31% [AT] < 10.91 ± 4.66% [healthy]). The triceps surae force-sharing strategy was different for the toe walking, heel walking, and the bilateral and unilateral heel drop with extended knee. This study provides evidence for altered triceps surae muscle force-sharing strategies during dynamic tasks in patients with AT. The influence of altered muscle force-sharing on the subtendon nonuniformity and/or the tendon loading should be explored in future work.

A THREE-DIMENSIONAL TIRE RING ON ELASTIC FOUNDATION MODEL IN ROLLING CONTACT WITH APPLICATION TO INTELLIGENT TIRES

ABSTRACT A new three-dimensional tire ring on elastic foundation model in rolling contact has been proposed and verified. The motivation is to apply this new physical model to the three-dimensional forces’ estimation for intelligent tires, a current research challenge in the automotive industry. The core contribution is the analytical solution of the three-dimensional tire deformation, stress, and forces in complex rolling contact. This new physical model is universal and efficient in linking intelligent tire signals with the solution results, thereby providing a powerful theoretical tool for intelligent tire modeling. Furthermore, the results have been validated by sensitivity analysis of key structural parameters on tire performance. In summary, through modeling, verification, and application in case studies, it has been shown that the proposed methodology can be used for real, practical three-dimensional forces estimation, offering the potential to simplify the vehicle state observer and benefit autonomous vehicles.

The effect of severe obesity on three-dimensional ground reaction force signals during walking

BackgroundThe gait pattern of adults with class I obesity [30 ≤ body mass index < 35kg/m2] was characterized by altered three-dimensional ground reaction force signals compared to lean adults (18.5 ≤ body mass index < 25 kg/m2). However, results might not be generalizable to adults with severe obesity (class II and III; body mass index ≥ 35 kg/m2). Hence, the purpose of the present study was to investigate the differences in relative ground reaction force signals, i.e., normalized by body weight, between adults with severe obesity and lean adults using functional principal component analysis. MethodsThirteen lean and eighteen sedentary adults with severe obesity performed a 5-min walking trial (1.11 m/s) on an instrumented treadmill. The first five functional principal components of the relative force signals (mediolateral, anterior-posterior, and vertical directions) were obtained using functional principal component analysis. Functional principal component scores were compared between groups using an analysis of covariance with age as covariable. FindingsFunctional principal component analysis reported a statistically significant group effect for first functional principal component score for mediolateral (P = 0.004), and second and fifth functional principal component scores for anterior-posterior (P ≤ 0.02) force signals. Adults with severe obesity displayed a greater mediolateral force during most of the stance but similar magnitudes of the anterior-posterior and vertical forces compared to lean adults. InterpretationTherefore, increasing the obesity level accentuates differences in mediolateral force but promotes no specific changes in anterior-posterior force likely due to chronic loading adaptation.

Poster 128: The Effect of Meniscotibial Ligament Disruption and Repair on Posterior Medial Meniscal Root Forces

Objectives: Meniscal injuries occur in as many as 1% of active people, and while outcomes for tears at the posterior medial meniscal root (PMMR) are well cited, the risk factors for injury have room for greater understanding. Incidence of disruption to the meniscotibial ligament (MTL) is correlated to occurrence of PMMR tears, suggesting that disruption to the MTL may increase forces at the PMMR and put the PMMR at greater risk of injury. The effect of an MTL disruption and repair on three-dimensional forces at the PMMR is unknown. The purpose of this study was to determine if MTL insufficiency alters forces at the PMMR., if a tenodesis procedure can restore PMMR forces to that of an MTL intact state, and to determine how knee flexion angle impacts PMMR root forces in the MTL intact and cut states. We hypothesize that all shear forces will increase following MTL disruption. Methods: Ten fresh-frozen cadaveric knees (Average age: 53.2 years) were tested in three conditions (Intact, MTL Cut, MTL Tenodesis). Specimens were dissected down to the knee capsule with ligaments intact. A 3D load cell construct (Figure 1) was installed inside the tibia such that 3D forces of the PMMR could be measured when the joint was loaded. Each specimen was mounted to a materials testing machine (Instron) via a custom fixture that allowed the specimen flexion angle to be changed in 30 degree increments. The specimen was first loaded to 500 N of compression with 0 N-m of torque, then to 5 N-m of internal torque with 50 N of compression, and finally to 5 N-m of external torque with 50 N of compression. 3D forces at the PMMR were recorded for all loading sequences, and the process was repeated for each flexion angle (0°, 30°, 60°, and 90°). PMMR forces along each axis (compression- tension, anterior-posterior shear, and medial-lateral shear) were compared across MTL testing states across flexion angles using linear mixed modelling. Results: When the joint was loaded in compression, MTL Cut state significantly increased compression of the PMMR (p = 0.0368), and the Tenodesis state did not significantly restore tension-compression forces of the PMMR (Intact→Tenodesis: p = 0.008)(Figure 1). When the joint was loaded in external rotation, the MTL Cut State significantly increased compression (p &lt; 0.0001), significantly decreased anterior shear (p = 0.0003), and, in high flexion angles, significantly decreased ML shear forces of the PMMR (Figure 1). The Tenodesis state did not significantly restore tension-compression (Intact→Tenodesis: p &lt; 0.0001) or AP forces (Intact→Tenodesis: p = 0.0002) of the PMMR (Figure 1). Conclusions: The key finding of this study is that MTL disruption increases compression forces and decreases AP shear forces seen at the root when the joint is loaded in compression and external rotation. These findings indicate that the intact MTL protects the PMMR from compression and shear loads during movements where the joint is loaded in compression and external rotation, movements that are clinically reported to put the knee joint at risk of PMMR injury. The authors believe these relationships are observed because the MTL may play a role in maintaining meniscal hoop stresses, which converts joint compression loads into tension and shear forces along the meniscal attachment points. When the MTL is disrupted, the other meniscal attachment points, the PMMR included, see elevated compression loads as a result. This is the first study to measure 3D forces at the PMMR, a necessary capability to assess PMMR injury risk. It is notable that the tenodesis procedure performed in this study did not restore PMMR forces. Future studies should develop improved centralization or tenodesis procedures to better restore PMMR forces and decrease likelihood for PMMR injury after MTL disruption.

Poster 140: The Effect of Posterior Tibial Slope and Flexion Angle on Posterior Medial Meniscal Root Forces

Objectives: Although the biomechanical and clinical consequences of posterior medial meniscal root (PMMR) tears have been previously reported, these have not been fully evaluated in terms of overall bony morphology. It is well documented that higher flexion angles lead to higher postero-medial pressure, with many groups proposing that PMMR tears are caused by elevated compression and shear forces at the root when the loaded knee is at high flexion angles. Additionally, several authors have advocated that increasing tibial plateau slope (PTS) is an anatomical risk factor for PMMR tears, due to the higher posterior shear forces at the root insertion site. Thus, the purposes of this study are to evaluate the forces across the PMMR utilizing a novel three-dimensional forces sensor with varying posterior tibial slopes and flexion angles. We hypothesized that an increased flexion angle and/or posterior tibial slope will result in increased posterior shear forces acting on the PMMR. Methods: Ten fresh-frozen cadaveric knees (53.2 mean age, all male) were tested in all combinations of the three states of posterior tibial slope (5⁰, 10⁰, 15⁰) and the four states of varying flexion angles (0⁰, 30⁰, 60⁰, and 90⁰). A novel three-axis sensor that determines force measurements in three orthogonal directions was installed below the posterior tibial plateau, with the specimen being mounted to a load frame which applied a 500-N axial load. A 5-Nm internal rotational (IR) torque was then applied. After the IR torque, a 5-Nm external rotational torque was applied. The amount of compression-tension and shear forces acting on the PMMR were measured. Results: Increased tibial slope significantly decreased tension and significantly increased compression of the PMMR (5°→10°: p = 0.0368, 5°→15°: p &lt; 0.0001, 10°→15°: p &lt; 0.0001) when the joint was loaded in compression. Increased tibial slope significantly increased anterior shear of the PMMR (5°→10°: p &lt; 0.0001, 5°→15°: p &lt; 0.0001, 10°→15°: p &lt; 0.0001) when the joint was internally rotated. Increased tibial slope significantly decreased compression of the PMMR (5°→10°: p = 0.0188, 5°→15°: p &lt; 0.0001) when the joint was externally rotated. Increased flexion angle significantly increased medial shear forces of the PMMR (0°→30°: p = 0.0362, 0°→60°: p = 0.0005, 0°→90°: p &lt; 0.0001, 30°→90°: p = 0.0434) when the joint was loaded in compression. 90° of flexion significantly increased tension of the PMMR (0°→90°: p = 0.0438, 30°→90°: p &lt; 0.0001, 60°→90°: p = 0.0005) when the joint was internally rotated. 30° of flexion angle significantly increased compression of the PMMR (0°→30°: p = 0.0004, 30°→60°: p = 0.0118, 30°→90°: p &lt; 0.0001) when the joint was externally rotated. Conclusions: Increased PTS results in an increase in compression forces acting on the posterior horn of the medial meniscus when the knee joint is loaded. Increases in flexion angles displays an increase in medial shear forces seen at the PMMR under a load. This increase in force may place the PMMR at increased risk of stress and potential failure after repair. This study begins to provide clinicians with information to create safer protocols to decrease the forces experienced at the PMMR after injury or postoperatively.

Development of an APPLE III undulator prototype with three-dimensional force compensation for SHINE

The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) plans to install several elliptically polarizing undulators (EPUs) as afterburners behind the planar undulator section to obtain nearly saturated circularly polarized free-electron laser (FEL) radiation. Therefore, the SHINE R&amp;amp;D project needs to develop a 4-m-long EPU with an effective magnetic field of 1.5 T, a period of 68 mm, and a minimum gap of 3 mm. A magnetic force compensation EPU prototype has recently been built and tested at the Shanghai Synchrotron Radiation Facility (SSRF) based on the addition of permanent magnets. This prototype can realize magnetic compensation under various polarization modes in all working gaps, thereby reducing the deformation of the girders and maintaining sufficient rigidity of the mechanical structure. A girder deformation monitoring system was established to obtain real force compensation feedback. The final magnetic field measurement results meet the physical requirements, and the proposed scheme can be used as an alternative to the EPU with a high magnetic field and large magnetic force.

Three-Dimensional Force Characterizations in Maxillary Molar Distalization: A Finite Element Study

Class II malocclusion is a very common condition in orthodontic patients. The reaction force and moment on the teeth induced by a maxillary segmental distalizer (MSD) are essential for understanding tooth movement, tipping, and rotation. This work quantified the three-dimensional (3D) reaction force and moment on canine and molar teeth induced by three different MSDs: the JVBarre (JVB), Carriere Motion 3D (CM3D), and CM3D Clear. A patient-specific mandibular model was reconstructed based on cone-beam computed tomography (CBCT) images. Each of the three MSDs was implanted using finite element analysis (FEA). The reaction force and moment were obtained. The results show that the JVB induced less extrusion force (15% less), tipping (90% less), and rotational moment (70% less) on the canine, compared with the other two CM3Ds. However, the JVB induced a relatively larger extrusion force, tipping, and rotational moment on the molar due to the hook location changing from the end to the middle of the bar. These observations were consistent with the 3D stress distribution of the MSDs. The mechanical understanding from this work may shed light on the optimal design of MSDs.

Overground Robotic Gait Trainer mTPAD Improves Gait Symmetry and Weight Bearing in Stroke Survivors

Stroke is a leading cause of disability, impairing the ability to generate propulsive forces and causing significant lateral gait asymmetry. We aim to improve stroke survivors’ gaits by promoting weight-bearing during affected limb stance. External forces can encourage this; e.g., vertical forces can augment the gravitational force requiring higher ground reaction forces, or lateral forces can shift the center of mass over the stance foot, altering the lateral placement of the center of pressure. With our novel design of a mobile Tethered Pelvic Assist Device (mTPAD) paired with the DeepSole system to predict the user’s gait cycle percentage, we demonstrate how to apply three-dimensional forces on the pelvis without lower limb constraints. This work is the first result in the literature that shows that with an applied lateral force during affected limb stance, the center of pressure trajectory’s lateral symmetry is significantly closer to a 0% symmetry (5.5%) than without external force applied (−9.8%,p&lt;0.05). Furthermore, the affected limb’s maximum relative pressure (p) significantly increases from 233.7p to 234.1p (p&lt;0.05) with an applied downward force, increasing affected limb loading. This work highlights how the mTPAD increases weight-bearing and propulsive forces during gait, which is a crucial goal for stroke survivors.

JUSTIFICATION OF THE CHOICE OF THE CALCULATION MODEL OF THE ESCALATOR TUNNEL IN FLAT AND SPATIAL SETTINGS

Purpose. To perform an analysis of analytical and numerical methods of mathematical modeling of an escalator tunnel. To identify the main characteristics and differences of methods based on flat or spatial settings. To justify the choice of the calculation model of the escalator tunnel and its setting. To justify the choice of the calculation model of the escalator tunnel and its construction. Methodology. To achieve the goal, a number of analytical methods based on a flat (2D) setting (Gap method, Volume loss control method, Convergence-confinement method) were analyzed. Approaches in numerical methods, in particular in the method of finite elements, which have successfully applied flat setting, are considered. The spatial (3D) setting in the finite element method is also analyzed. Analysis of a numerical experiment based on 3D models shows that the three-dimensional structure forces interpretation decisions that are not taken into account in the cross-section, that is, in the two-dimensional model. Findings. Finite-element models of the escalator tunnel were developed in flat and spatial settings, and the 2D model with a thickness of 1 m repeated the conditions of the 3D model in its middle part. The obtained parameters of the stress-strain state were subjected to comparative analysis. It was found that the values of the norms of horizontal and vertical stresses in the fragment of the 3D model (middle) and in the 2D model differ by 3.2 and 7.2 %, respectively. Originality. Based on the results of the justification of the choice of the calculation model of the escalator tunnel, it was proved that the use of 2D models is adequate for the system of interaction of the escalator tunnel with the surrounding massif. This statement is evidenced by the almost identical distribution of stresses and strains in finite-element models in flat and spatial settings. Practical value. In the course of research, it has been proven that the flat finite-element model of the escalator tunnel is adequate for the given task, provided that it is used in several characteristic sections of the escalator tunnel, that is, the creation of a number of models in 2D, which allows considering its position along the length of the calculated tunnel.

Optimization of in-brace corrective force in adolescents with Lenke type 5 curve using finite element model

BackgroundPelvic parameters have been taken into consideration for the evaluation of the outcomes of bracing in AIS. To discuss the stress required to correct the pelvic deformity related to Lenke5 adolescent idiopathic scoliosis (AIS) by finite element analysis, and provide a reference for the shaping of the pelvic region of the brace.MethodsAn three-dimensional (3D) corrective force on the pelvic area was defined. Computed tomography images were used to reconstruct a 3D model of Lenke5 AIS. Computer-aided engineering software Abaqus was used to implement finite element analysis. By adjusting the magnitude and position of corrective forces, coronal pelvic coronal plane rotation (PCPR) and Cobb angle (CA) of lumbar curve in the coronal plane, horizontal pelvic axial plane rotation, and apical vertebra rotation (AVR) were minimized to achieve the best effect on the spine and pelvic deformity correction. The proposed corrective conditions were divided into three groups: (1) forces applied on X-axis; (2) forces applied both in the X- and Y-axis; and (3) forces applied along the X-, Y-, and Z-axis at the same time.ResultsIn three groups, CA correction reduced by 31.5%, 42.5%, and 59.8%, and the PCPR changed to 12°, 13°, and 1° from 6.5°, respectively. The best groups of correction forces should simultaneously locate on the sagittal, transverse, and coronal planes of the pelvis.ConclusionsFor Lenke5 AIS, 3D correction forces can sufficiently reduce scoliosis and pelvic asymmetrical state. Force applied along the Z-axis is vital to correct the pelvic coronal pelvic tilt associated with Lenke5 AIS.