A Self-Deployment Hexapod Model for a Space Application

2007 ◽  
Author(s):  
G. Aridon ◽  
A. Al Majid ◽  
L. Blanchard ◽  
D. Re´mond ◽  
R. Dufour
Keyword(s):  
Numerical Model ◽  
Dynamic Model ◽  
Hysteretic Behavior ◽  
Simulation Tool ◽  
Space Application ◽  
Tensor Representation ◽  
Restoring Force ◽  
Partial Derivatives ◽  
Efficient Simulation ◽  
The Impact

This paper presents an efficient simulation tool for predicting a self deployment of an on-board deployable hexapod based on the release of stored strain energies provided by six tape-spring actuators. Six restoring force models describe their hysteretic behavior. A formulation of a direct dynamic model developed with a Lagrangian approach is achieved. Furthermore, tensor representation is used to condense and simplify the calculation of Lagrangian partial derivatives. Results are compared with a numerical model that performs the recursive Newton-Euler technique. Finally, the impact of the excitation of the base on the deployment performances is evaluated taking advantage of the proposed restoring force models.

A Self-Deployment Hexapod Model for a Space Application

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
G. Aridon ◽  
A. Al Majid ◽  
L. Blanchard ◽  
D. Rémond ◽  
R. Dufour
Keyword(s):  
Numerical Model ◽  
Dynamic Model ◽  
Strain Energy ◽  
The Self ◽  
Hysteretic Behavior ◽  
Simulation Tool ◽  
Space Application ◽  
Tensor Representation ◽  
Restoring Force ◽  
The Impact

This paper presents a simulation tool for predicting the self-deployment of an on-board deployable hexapod based on the release of strain energy stored in six tape-spring actuators. Their hysteretic behavior is described by six restoring force models, and a formulation of a direct dynamic model developed with a Lagrangian approach is performed. Furthermore, tensor representation is used to condense and simplify the calculation of Lagrangian partial derivatives. The results are compared with a numerical model that implements the recursive Newton–Euler technique. Finally, the impact of base excitations on the hexapod deployment performances is evaluated by using the proposed restoring force models.

Effect of Frame-Restoring Force Characteristics on the Pounding Response of Multiple-Frame Bridges

2005 ◽  
Vol 21 (4) ◽  
pp. 1113-1135 ◽  
Author(s):  
Susendar Muthukumar ◽  
Reginald DesRoches
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Hysteretic Behavior ◽  
Impact Response ◽  
Far Field ◽  
Restoring Force ◽  
Bridge Model ◽  
Multiple Frame ◽  
The Impact ◽  
Force Characteristics

This study examines the effect of column hysteretic behavior on the impact response of adjacent frames in multiple-frame bridges. A simplified planar analytical bridge model is developed including inelastic frame action, nonlinear hinge behavior, and abutment effects. Pounding is simulated using a stereomechanical approach. The frame hysteretic models considered include the elasto-plastic and bilinear (traditional), Q-Hyst (stiffness-degrading), and pivot hysteresis (strength-degrading) models. Analytical studies conducted on adjacent bridge frames reveal that the traditional models underestimate the stiff frame displacement amplification due to pounding, and overestimate the flexible frame displacement amplification, when compared with other hysteretic models. A stiffness-degrading model is recommended to accurately estimate the pounding response of bridge frames subjected to far-field ground motion. The use of a strength-degrading model increases the stiff frame displacement amplification by 125% when compared to the stiffness-degrading model for highly out-of-phase frames, and is recommended in the presence of near-field ground motions.

332-OR: Determining the Impact of Additional Macronutrients on the Glycemic-Insulin Dynamic Model

Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 332-OR
Author(s):  
BOYI JIANG ◽  
YUXIANG ZHONG ◽  
PRATIK AGRAWAL ◽  
TONI L. CORDERO ◽  
ROBERT VIGERSKY
Keyword(s):  
Dynamic Model ◽  
The Impact

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals A Model for the Thermal Behaviour of an Offshore Cable Installed in a J-Tube

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 31
Author(s):  
Jeremy Arancio ◽  
Ahmed Ould El Moctar ◽  
Minh Nguyen Tuan ◽  
Faradj Tayat ◽  
Jean-Philippe Roques
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Model ◽  
Thermal Behaviour ◽  
Energy Production ◽  
Power Transmission ◽  
Temperature Fields ◽  
Sobol Indices ◽  
Lumped Element ◽  
Thermal Phenomena ◽  
The Impact

In the race for energy production, supplier companies are concerned by the thermal rating of offshore cables installed in a J-tube, not covered by IEC 60287 standards, and are now looking for solutions to optimize this type of system. This paper presents a numerical model capable of calculating temperature fields of a power transmission cable installed in a J-tube, based on the lumped element method. This model is validated against the existing literature. A sensitivity analysis performed using Sobol indices is then presented in order to understand the impact of the different parameters involved in the heating of the cable. This analysis provides an understanding of the thermal phenomena in the J-tube and paves the way for potential technical and economic solutions to increase the ampacity of offshore cables installed in a J-tube.

Influence of the backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set

2016 ◽  
Vol 231 (11) ◽  
pp. 2025-2041 ◽  
Author(s):  
Shijing Wu ◽  
Haibo Zhang ◽  
Xiaosun Wang ◽  
Zeming Peng ◽  
Kangkang Yang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Planetary Gear ◽  
Tooth Wear ◽  
Transmission Error ◽  
Gear Transmission ◽  
Tooth Surface ◽  
Contact Ratio ◽  
The Impact

Backlash is a key internal excitation on the dynamic response of planetary gear transmission. After the gear transmission running for a long time under load torque, due to tooth wear accumulation, the backlash between the tooth surface of two mating gears increases, which results in a larger and irregular backlash. However, the increasing backlash generated by tooth accumulated wear is generally neglected in lots of dynamics analysis for epicyclic gear trains. In order to investigate the impact of backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set, in this work, first a static tooth surface wear prediction model is incorporated with a dynamic iteration methodology to get the increasing backlash generated by tooth accumulated wear for one pair of mating teeth under the condition that contact ratio equals to one. Then in order to introduce the tooth accumulated wear into dynamic model of compound planetary gear set, the backlash excitation generated by tooth accumulated wear for each meshing pair in compound planetary gear set is given under the condition that contact ratio equals to one and does not equal to one. Last, in order to investigate the impact of the increasing backlash generated by tooth accumulated wear on dynamic response of compound planetary gear set, a nonlinear lumped-parameter dynamic model of compound planetary gear set is employed to describe the dynamic relationships of gear transmission under the internal excitations generated by worn profile, meshing stiffness, transmission error, and backlash. The results indicate that the introduction of the increasing backlash generated by tooth accumulated wear makes a significant influence on the bifurcation and chaotic characteristics, dynamic response in time domain, and load sharing behavior of compound planetary gear set.

Dynamics of the Gear Train Set in Wind Turbine

2011 ◽  
Vol 697-698 ◽  
pp. 701-705
Author(s):  
D.D. Ji ◽  
Y.M. Song ◽  
J. Zhang
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Harmonic Balance Method ◽  
Planetary Gear ◽  
Gear Train ◽  
Dynamic Responses ◽  
Multi Stage ◽  
Lumped Parameter ◽  
Cartesian Coordinate ◽  
The Impact

A lumped-parameter dynamic model for gear train set in wind turbine is proposed to investigate the dynamics of the speed-increasing gear box. The proposed model is developed in a universal Cartesian coordinate, which includes transversal and torsional deflections of each component, time-varying mesh stiffness, gear profile errors and external excitations. By solving the dynamic model, a modal analysis is performed. The results indicate that the modal properties of the multi-stage gear train in wind turbine are similar to those of a single-stage planetary gear set. A harmonic balance method (HBM) is used to obtain the dynamic responses of the gearing system. The responses give insight into the impact of excitations on the vibrations.

Fractality of Simulated Fracture

2009 ◽  
Vol 409 ◽  
pp. 154-160 ◽  
Author(s):  
Petr Frantík ◽  
Zbyněk Keršner ◽  
Václav Veselý ◽  
Ladislav Řoutil
Keyword(s):  
Numerical Model ◽  
Elastic Plate ◽  
Model Simulation ◽  
Element Model ◽  
The Other ◽  
Particle Model ◽  
Discrete Element Model ◽  
Fractal Nature ◽  
Discrete Elements ◽  
The Impact

The paper is focussed on numerical simulations of the fracture of a quasi-brittle specimen due to its impact onto a fixed rigid elastic plate. The failure of the specimen after the impact is modelled in two ways based on the physical discretization of continuum: via physical discrete elements and pseudo-particles. Advantages and drawbacks of both used methods are discussed. The size distribution of the fragments of the broken specimen resulting from physical discrete element model simulation follows a power law, which indicates the ability of the numerical model to identify the fractal nature of the fracture. The pseudo-particle model, on the other side, can successfully predict the kinematics of the fragments of the specimen under impact failure.

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