Simulation and Optimization of an Adjustable Inlet Guide Vane for Industrial Turbo Compressors

2008 ◽  
Author(s):  
Michael Hensges
Keyword(s):  
Guide Vane ◽  
Rigid Bodies ◽  
Inlet Guide Vane ◽  
Fe Model ◽  
Fe Method ◽  
Friction Forces ◽  
Simulation And Optimization ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction

To investigate the kinematics and dynamics of an adjustable inlet guide vane mechanism (IGV) for industrial turbo compressors, an IGV was modeled as a multibody system (MBS) consisting of elastic interconnections and rigid bodies. Besides investigating the IGV kinematics, its vibrations and structural strength were also verified numerically. The kinematic analyses enabled the design to be optimized in terms of undesirable collisions between the interconnected bodies. The pressure exerted on the guide vanes, which is calculated by CFD simulations, forms a set of forces and torques for each blade. These sets were created for two different performance maps, referred to in the following as Gas I and Gas II. Calculating the desired drive torque, joint reaction forces and the driving ring’s displacements were the essential inputs for the dynamic multibody analyses performed. These investigations showed that the desired torque to drive the mechanism is governed by the sliding element’s friction forces. The gas forces were able to raise the torque by roughly 6% and 32.6% for Gas I and II, respectively. Due to uncertainties in the determination of the friction coefficients, the highest expected values were taken into account for selecting an accurate actuator for the IGV. The strength and vibration analyses were carried out using the Finite Element (FE) Method. All computed critical natural frequencies of the IGV can be empirically considered to be highly damped resonances in the actual system due to joint friction effects. Reaction forces determined by the dynamic multibody analyses were transferred as loads to the FE model. In most cases, the joint reaction forces have been so low that no further investigations were necessary. Hence, verification of strength was carried out using a contact FE analysis for the highest loading condition between the assembly and the pin, which transfers the entire drive force from a lever into the driving ring.

Comparison of Three-Dimensional Patellofemoral Joint Reaction Forces in Persons With and Without Patellofemoral Pain

2014 ◽  
Vol 30 (4) ◽  
pp. 493-500 ◽  
Author(s):  
Yu-Jen Chen ◽  
Christopher M. Powers
Keyword(s):  
Patellofemoral Joint ◽  
Three Dimensional ◽  
Patellofemoral Pain ◽  
Biomechanical Analysis ◽  
Control Group ◽  
Three Dimensional Model ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Magnetic Resonance Imaging Mri ◽  
Joint Reaction

The purpose of this study was to determine if persons with patellofemoral pain (PFP) exhibit differences in patellofemoral joint reaction forces (PFJRFs) during functional activities. Forty females (20 PFP, 20 controls) underwent two phases of data collection: (1) magnetic resonance imaging (MRI) and (2) biomechanical analysis during walking, running, stair ascent, and stair descent. A previously described three-dimensional model was used to estimate PFJRFs. Resultant PFJRFs and the orthogonal components were reported. The PFP group demonstrated lower peak resultant PFJRFs and posterior component and superior component of the PFJRFs compared with the control group across all conditions. However, the PFP group had a higher peak lateral component of the PFJRF in three out of the four conditions evaluated. The lower resultant PFJRFs suggested that individuals with PFP may employ strategies to minimize patellofemoral joint loading, but it did not result in diminished lateral forces acting on the patella.

Prediction of Antagonistic Muscle Forces Using Inverse Dynamic Optimization During Flexion/Extension of the Knee

1999 ◽  
Vol 121 (3) ◽  
pp. 316-322 ◽  
Author(s):  
G. Li ◽  
K. R. Kaufman ◽  
E. Y. S. Chao ◽  
H. E. Rubash
Keyword(s):  
Dynamic Optimization ◽  
Optimization Procedure ◽  
Muscle Forces ◽  
Inverse Dynamic ◽  
Optimization Criteria ◽  
Flexion Extension ◽  
Antagonistic Muscle ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction

This paper examined the feasibility of using different optimization criteria in inverse dynamic optimization to predict antagonistic muscle forces and joint reaction forces during isokinetic flexion/extension and isometric extension exercises of the knee. Both quadriceps and hamstrings muscle groups were included in this study. The knee joint motion included flexion/extension, varus/valgus, and internal/external rotations. Four linear, nonlinear, and physiological optimization criteria were utilized in the optimization procedure. All optimization criteria adopted in this paper were shown to be able to predict antagonistic muscle contraction during flexion and extension of the knee. The predicted muscle forces were compared in temporal patterns with EMG activities (averaged data measured from five subjects). Joint reaction forces were predicted to be similar using all optimization criteria. In comparison with previous studies, these results suggested that the kinematic information involved in the inverse dynamic optimization plays an important role in prediction of the recruitment of antagonistic muscles rather than the selection of a particular optimization criterion. Therefore, it might be concluded that a properly formulated inverse dynamic optimization procedure should describe the knee joint rotation in three orthogonal planes.

Influence of the Musculotendon Dynamics on the Muscle Force-Sharing Problem of the Shoulder—A Fully Inverse Dynamics Approach

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Quental Carlos ◽  
Azevedo Margarida ◽  
Ambrósio Jorge ◽  
Gonçalves S. B. ◽  
Folgado João
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Glenohumeral Joint ◽  
Inverse Dynamic ◽  
Force Sharing ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Muscle Activations ◽  
Joint Reaction

Abstract Most dynamic simulations are based on inverse dynamics, being the time-dependent physiological nature of the muscle properties rarely considered due to numerical challenges. Since the influence of muscle physiology on the consistency of inverse dynamics simulations remains unclear, the purpose of the present study is to evaluate the computational efficiency and biological validity of four musculotendon models that differ in the simulation of the muscle activation and contraction dynamics. Inverse dynamic analyses are performed using a spatial musculoskeletal model of the upper limb. The muscle force-sharing problem is solved for five repetitions of unloaded and loaded motions of shoulder abduction and shoulder flexion. The performance of the musculotendon models is evaluated by comparing muscle activation predictions with electromyography (EMG) signals, measured synchronously with motion for 11 muscles, and the glenohumeral joint reaction forces estimated numerically with those measured in vivo. The results show similar muscle activations for all muscle models. Overall, high cross-correlations are computed between muscle activations and the EMG signals measured for all movements analyzed, which provides confidence in the results. The glenohumeral joint reaction forces estimated compare well with those measured in vivo, but the influence of the muscle dynamics is found to be negligible. In conclusion, for slow-speed, standard movements of the upper limb, as those studied here, the activation and musculotendon contraction dynamics can be neglected in inverse dynamic analyses without compromising the prediction of muscle and joint reaction forces.

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