scholarly journals A Finite Element Model for Estimation of Contact Dynamics During a Jumping Movement on a Trampoline

2020 ◽  
Vol 73 (1) ◽  
pp. 59-72
Author(s):  
Jingguang Qian ◽  
Yiling Mao ◽  
Xiao Tang ◽  
Zhaoxia Li ◽  
Chen Wen ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Musculoskeletal Model ◽  
Contact Dynamics ◽  
Lower Extremity Muscle ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Left And Right ◽  
Joint Reaction

AbstractIn order to fully understand contact dynamics on a trampoline, a simulation approach using a musculoskeletal model coupled with a dynamic model of the trampoline is essential. The purpose of the study was to examine dynamics and selected lower extremity muscle forces in a landing and jumping movement on a trampoline, using a combination of finite element modeling and musculoskeletal modeling. The rigid frame of the trampoline was modeled in ADAMS and coupled with a finite element model of the elastic trampoline net surface in ANSYS. A musculoskeletal model of an elite trampoline athlete was further developed in LifeMod and combined with the finite element model of the trampoline. The results showed that the peak trampoline reaction forces (TRF) were 3400 N (6.6 BW) and 2900 N (5.6 BW) for the left and right limb, respectively. The right hip, knee and ankle joint reaction forces reached the maximum between 3000-4000 N (5.8 – 7.7 BW). The gluteus maximum and quadriceps reached the maximum muscle force of 380 N (0.7 BW) and 780 N (1.5 BW), respectively. Asymmetric loading patterns between left and right TRFs and lower extremities joint reaction forces were observed due to the need to generate the rotational movement during the takeoff. The observed rigid and erect body posture suggested that the hip and knee extensors played important roles in minimizing energy absorption and maximizing energy generation during the trampoline takeoff.

scholarly journals Finite element study of sitting configurations to reduce sacroiliac joint loads

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Isabella Bozzo ◽  
Brandon Malz
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Sacroiliac Joint ◽  
Isotropic Material ◽  
Element Model ◽  
Low Back ◽  
Prolonged Sitting ◽  
Lower Back ◽  
Reaction Forces ◽  
Joint Loads

Low back pain can be caused by prolonged sitting, originating in the sacroiliac joint (SIJ) in up to 30% of patients. The goal of this study was to develop a finite element model of the lower back and pelvis to study sitting configurations that could minimize the loads in the SIJ while sitting. The configurations were based on chair designs with geometries known to show some benefits according to literature: a 5° downward seat pan tilt and a 20° backrest recline. Both chairs were evaluated in neutral spine position with upright posture and 30° forward leaning configurations. A finite element model of the lumbar spine, pelvis and femurs was developed to compute the reaction forces at the SIJ. The intricate spinal geometry was simplified, and isotropic material properties were assumed for all components. The chair reaction forces were first computed analytically, then inputted as loads on the model. The results demonstrate that the improved sitting configuration reduced the loads in the SIJ compared to a conventional chair in both upright and forward leaning positions by 5.57 % body weight (BW) and 14.18 %BW, respectively. The proposed sitting configuration with a downward inclined seat pan and forward leaning back was shown to be an effective method to reduce SIJ loads.

A subject-specific integrative biomechanical framework of the pelvis for gait analysis

2018 ◽  
Vol 232 (11) ◽  
pp. 1083-1097
Author(s):  
Emiliano P Ravera ◽  
Marcos J Crespo ◽  
Paola A Catalfamo Formento
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Gait Analysis ◽  
Material Properties ◽  
Element Model ◽  
Musculoskeletal Model ◽  
Pelvic Bone ◽  
Subject Specific ◽  
Specific Material ◽  
The Finite Element Model

Analysis of the human locomotor system using rigid-body musculoskeletal models has increased in the biomechanical community with the objective of studying muscle activations of different movements. Simultaneously, the finite element method has emerged as a complementary approach for analyzing the mechanical behavior of tissues. This study presents an integrative biomechanical framework for gait analysis by linking a musculoskeletal model and a subject-specific finite element model of the pelvis. To investigate its performance, a convergence study was performed and its sensitivity to the use of non-subject-specific material properties was studied. The total hip joint force estimated by the rigid musculoskeletal model and by the finite element model showed good agreement, suggesting that the integrative approach estimates adequately (in shape and magnitude) the hip total contact force. Previous studies found movements of up to 1.4 mm in the anterior–posterior direction, for single leg stance. These results are comparable with the displacement values found in this study: 0–0.5 mm in the sagittal axis. Maximum von Mises stress values of approximately 17 MPa were found in the pelvic bone. Comparing this results with a previous study of our group, the new findings show that the introduction of muscular boundary conditions and the flexion–extension movement of the hip reduce the regions of high stress and distributes more uniformly the stress across the pelvic bone. Thus, it is thought that muscle force has a relevant impact in reducing stresses in pelvic bone during walking of the finite element model proposed in this study. Future work will focus on including other deformable structures, such as the femur and the tibia, and subject-specific material properties.

How Well Does a Musculoskeletal Model Predict GH-Joint Contact Forces? Comparison With In-Vivo Data

2009 ◽  
Author(s):  
A. Asadi Nikooyan ◽  
H. E. J. Veeger ◽  
P. Westerhoff ◽  
F. Graichen ◽  
G. Bergmann ◽  
...  
Keyword(s):  
Large Scale ◽  
Musculoskeletal Model ◽  
Contact Forces ◽  
Motion Data ◽  
Joint Reaction Forces ◽  
Joint Contact ◽  
Reaction Forces ◽  
Quantitative Validation ◽  
Joint Reaction

The Delft Shoulder and Elbow Model (DSEM), a large-scale musculoskeletal model, allows for estimation of individual muscle and joint reaction forces in the shoulder and elbow complex. Although the model has been qualitatively verified previously using EMG signals, quantitative validation has not yet been feasible. In this paper we report on the validation of the DSEM by comparing the GH-joint contact forces estimated by the DSEM with the in-vivo forces measured by a recently developed instrumented shoulder endoprosthesis, capable of measuring the glenohumeral (GH) joint contact forces in-vivo [1]. To validate the model, two patients with instrumented shoulder hemi-arthroplasty were measured. The measurement process included the collection of motion data as well as in-vivo joint reaction forces. Segment and joint angles were used as the model inputs to estimate the GH-joint contact forces. The estimated and recorded GH-joint contact forces for Range of Motion (RoM) and force tasks were compared based on the magnitude of the resultant forces. The results show that the estimated force follows the measured force for abduction and anteflexion motions up to 80 and 50 degrees arm elevations, respectively, while they show different behaviors for angles above 90 degrees (decrease is estimated but increase is measured). The DSEM underestimates the peak force for RoM (up to 38% for abduction motion and 64% for anteflexion motion), while overestimates the peak forces (up to 90%) for most directions of performing the force tasks.

Train-Induced Load Effects on the Thermal Track Buckling

2019 ◽  
Author(s):  
Giovanni Pio Pucillo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Limit Value ◽  
Lateral Resistance ◽  
Lateral Plane ◽  
Load Effects ◽  
Reaction Forces ◽  
Curve Radius ◽  
Center Distance

Thermal track buckling is probably the major problem due to the advent of continuous welded rail track. In fact, when the rails temperature rises over a critical value, the track can buckle, suddenly or progressively, in the lateral plane. Both poor ballast conditions and large lateral alignment defects are the principal causes of such phenomenon. In a previous paper, a parametric finite element model for thermal track buckling simulation was presented and validated by comparison with analytical results of the literature. In this study, the finite element model has been further validated by comparison with analytical and numerical results obtained by three other authors. Moreover, to take into account the effect on the buckling temperatures of the vertical loads due to train passes, the tie-ballast lateral resistance has been modified along the track, taking into account the vertical reaction forces distribution induced by axle loads. A sensitivity analysis has been carried out both for tangent and curved track, considering two values of the alignment defect amplitude, and different values of the parameters that characterize actual railway vehicles. It is found that the conditions to trigger progressive buckling (△Tmax ≈ △Tmin) are attained with small values of the truck center distance, and in a more accentuated manner in the presence of high values of the lateral alignment defect. △Tmax and △Tmin increase with axle spacing, and this increase is more pronounced for low values of the truck center spacing. △Tmax and △Tmin also increase with curve radius, but decrease for increasing values of the misalignment defect amplitude. In explosive buckling conditions (△Tmax ≠ △Tmin), there is a limit value of the truck center distance above which the vertical load has no more effects, and the results of the static thermal buckling are found.

Modeling of Multiteeth Contact Meshing Gear Dynamics with Backlash and Coincidence Degree

2012 ◽  
Vol 562-564 ◽  
pp. 842-846 ◽  
Author(s):  
Zhen Xu ◽  
Hua Deng ◽  
Qi Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Coincidence Degree ◽  
Element Model ◽  
Contact Dynamics ◽  
Dynamics Model ◽  
Inertial Property ◽  
Gear Teeth ◽  
Proposed Model ◽  
Gear Contact

In the present paper, a multiteeth meshing gear contact dynamics model is proposed by introducing a modified robotic contact model. The inertial property, backlash of gear teeth and coincidence degree of gear meshing are considered into the model. In addition, the proposed model is used to simulate discontinuous meshing gear contact. Simultaneously, the gear meshing contact dynamical finite element model is also simulated using the Ansys/LS-DYNA software to demonstrate the rationality of the proposed model.

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