Accuracy and robustness of four basic single degree of freedom methods for determining the modal parameters of non-lightly damped systems

2012 ◽  
Vol 331 (24) ◽  
pp. 5191-5208 ◽  
Author(s):  
David K. Anthony ◽  
Francisco Simón
Keyword(s):  
Degree Of Freedom ◽  
Modal Parameters ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Damped Systems

An Efficient Method for Compensating Truncated Higher Modes in Structural Dynamics Modification

1986 ◽  
Vol 200 (1) ◽  
pp. 41-48 ◽  
Author(s):  
K R Chung ◽  
C W Lee
Keyword(s):  
Structural Dynamics ◽  
Efficient Method ◽  
Curve Fitting ◽  
Modal Parameters ◽  
Frequency Range ◽  
Single Degree Of Freedom ◽  
Higher Modes ◽  
Numerical Example ◽  
Single Degree ◽  
Damped Systems

An efficient method for compensating the effects of the truncated higher modes in structural dynamics modification (SDM) is developed to predict the accurate modal parameters of locally modified structures. The effects of the truncated higher modes are represented by a fictitious, effective mode residing beyond the frequency range of interest. The modal parameters are then easily obtained by the iterative single degree-of-freedom curve-fitting technique developed for lightly damped systems. A numerical example demonstrates the effectiveness of the improved SDM technique.

Kinematic comparison of single degree-of-freedom robotic gait trainers

2021 ◽  
Vol 159 ◽  
pp. 104258
Author(s):  
Jeonghwan Lee ◽  
Lailu Li ◽  
Sung Yul Shin ◽  
Ashish D. Deshpande ◽  
James Sulzer
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Robotic Gait

Single-Degree-of-Freedom Based Pressure-Impulse Diagrams for Blast Damage Assessment

2014 ◽  
Vol 567 ◽  
pp. 499-504 ◽  
Author(s):  
Zubair Imam Syed ◽  
Mohd Shahir Liew ◽  
Muhammad Hasibul Hasan ◽  
Srikanth Venkatesan
Keyword(s):  
Damage Assessment ◽  
Structural Response ◽  
Blast Loading ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Negative Phase ◽  
Single Degree Of Freedom ◽  
Pressure Impulse ◽  
Single Degree ◽  
Structural Resistance

Pressure-impulse (P-I) diagrams, which relates damage with both impulse and pressure, are widely used in the design and damage assessment of structural elements under blast loading. Among many methods of deriving P-I diagrams, single degree of freedom (SDOF) models are widely used to develop P-I diagrams for damage assessment of structural members exposed to blast loading. The popularity of the SDOF method in structural response calculation in its simplicity and cost-effective approach that requires limited input data and less computational effort. The SDOF model gives reasonably good results if the response mode shape is representative of the real behaviour. Pressure-impulse diagrams based on SDOF models are derived based on idealised structural resistance functions and the effect of few of the parameters related to structural response and blast loading are ignored. Effects of idealisation of resistance function, inclusion of damping and load rise time on P-I diagrams constructed from SDOF models have been investigated in this study. In idealisation of load, the negative phase of the blast pressure pulse is ignored in SDOF analysis. The effect of this simplification has also been explored. Matrix Laboratory (MATLAB) codes were developed for response calculation of the SDOF system and for repeated analyses of the SDOF models to construct the P-I diagrams. Resistance functions were found to have significant effect on the P-I diagrams were observed. Inclusion of negative phase was found to have notable impact of the shape of P-I diagrams in the dynamic zone.

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