Multibody Dynamic Simulation of the Lunar Landing

2012 ◽  
pp. 1-5 ◽  
Author(s):  
Huinam Rhee ◽  
Sang Jin Park ◽  
Tae Sung Kim
Keyword(s):  
Dynamic Simulation ◽  
Lunar Landing ◽  
Multibody Dynamic

Random Loads Fatigue: The Use of Spectral Methods Within Multibody Simulation

2005 ◽  
Author(s):  
Claudio Braccesi ◽  
Filippo Cianetti ◽  
Luca Landi
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Dynamic Simulation ◽  
Fatigue Damage ◽  
Spectral Methods ◽  
Mechanical Systems ◽  
Frequency Domain Method ◽  
Stress And Strain ◽  
Damage Evaluation ◽  
Multibody Dynamic

The evaluation of the fatigue damage performed by using the Power Spectral Density function (PSD) of stress and strain state is proving to be extremely accurate for a family of random processes characterized by the property of being stationary. The present work’s original contribution is the definition of a methodology which extracts stress and strain PSD matrices from components modelled using a modal approach (starting from a finite element modelling and analysis) within mechanical systems modelled using multibody dynamic simulation and subject to a generic random load (i.e. multiple-input, with partially correlated inputs). This capability extends the actual stress evaluation scenario (principally characterised by the use of finite element analysis approach) to the multibody dynamic simulation environment, more powerful and useful to simulate complex mechanical systems (i.e. railway, automotive, aircraft and aerospace systems). As regards the fatigue damage evaluation, a synthesis approach to evaluate an equivalent stress state expressed in terms of the PSD function of Preumont’s “equivalent von Mises stress (EVMS)”, starting from the complete stress state representation expressed in terms of PSD stress matrix and easily usable in the consolidated spectral methods, is proposed. This approach allows and has allowed the use of the above methods such as the Dirlik formula as a damage evaluation method. An additional result is the conception and implementation of a frequency domain method for the component’s most probable state of stress, allowing quickly identification of the most stressed and damageble locations. The described methodologies were developed and embedded into commercial simulation codes and verified by using as a test case a simple reference multibody model with a simple flexible component.

Determination of Significance of Stress Stiffening Effects in Flexible Multibody Dynamic Systems

1992 ◽  
Author(s):  
Jeha Ryu ◽  
Sang Sup Kim ◽  
Sung-Soo Kim
Keyword(s):  
Dynamic Simulation ◽  
Dynamic Systems ◽  
Stiffness Matrix ◽  
Multibody Systems ◽  
Flexible Body ◽  
Multibody Dynamic ◽  
Flexible Multibody ◽  
Multibody Dynamic System ◽  
Modal Stress

Abstract This paper presents a criterion for determining whether or not a flexible multibody dynamic system reveals stress stiffening effects. In the proposed criterion, the eigenvalue variation that results from adding the modal stress stiffness matrix to the conventional linear modal stiffness matrix is examined numerically before actual dynamic simulation. If the variation is sufficiently large for any flexible body, then stress stiffening effects are said to be significant and must be included in dynamic simulation of flexible multibody systems. Since the criterion uses the most general stress stiffness matrix, which can be represented as a function of applied and constraint reaction loads as well as of a system of 12 inertial loads, this criterion is applicable to any general flexible multibody dynamic systems. Several numerical results are presented to show the effectiveness of the proposed criterion.

Efficient Modal Approach for Flexible Multibody Dynamic Simulation

2003 ◽  
Vol 31 (1) ◽  
pp. 1-23 ◽  
Author(s):  
W. Pan ◽  
S. Mao ◽  
E. J. Haug ◽  
D. Solis
Keyword(s):  
Dynamic Simulation ◽  
Modal Approach ◽  
Multibody Dynamic ◽  
Flexible Multibody
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