ANALYSIS OF IMPACT FORCE VARIATION DURING COLLISION OF TWO BODIES USING A SINGLE-DEGREE-OF-FREEDOM SYSTEM MODEL

2000 ◽  
Vol 229 (4) ◽  
pp. 823-835 ◽  
Author(s):  
C. RAJALINGHAM ◽  
S. RAKHEJA
Author(s):  
Akira Maekawa ◽  
Katsuhisa Fujita ◽  
Michiaki Suzuki

This study describes the response reduction caused by coupling between the beam-type and the oval-type vibrations of a cylindrical water storage tank under seismic excitation. In this study, the seismic response experiment is performed by using a 1/10 reduced scale model of an actual tank and then numerical simulation is performed by the simplified model. The authors conducted the sinusoidal response experiment for the tank and reported that the coupling between the beam-type and the oval-type vibrations causes the resonance frequency of the beam-type vibration to shift to the lower frequency and the response in the beam-type vibration (the response of the tank) to reduce. The seismic response experiment of the tank model filled with water up to 95% is performed by a shaking table. The El Centro 1940 NS and the improved standard seismic wave for Japanese LWR are used as the input seismic wave. The experimental results show that the maximum response acceleration does not enlarge linearly as the maximum input acceleration increases. The dominant resonance frequency slightly shifts to the lower frequency as the maximum input acceleration increases. It is concluded that the coupling between the beam-type and the oval-type vibrations make an influence on the beam-type vibration in seismic excitation. In the meantime, the authors propose the nonlinear single-degree-of-freedom system model to explain that the vibration response of the tank reduces. This model is based on geometric nonlinearity due to the out-of-plane deformation of the side-wall of the tank caused by the oval-type vibration. The numerical simulation of the seismic response is conducted using the nonlinear single-degree-of-freedom system model proposed by the authors. The analytical results agree with the experimental results as a general trend. Therefore, it is concluded that the response reduction of the tank is generated by coupling between the beam-type and the oval-type vibrations in the seismic excitation as well as the sinusoidal excitation. In addition, the response reduction rate of the tank under much larger seismic excitation can be estimated by using the nonlinear single-degree-of-freedom system model.


2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Cody Leeheng Chan ◽  
Kwun-Lon Ting

According to Camus’ theorem, for a single degree-of-freedom (DOF) three-body system with the three instant centers staying coincident, a point embedded on a body traces a pair of conjugated curves on the other two bodies. This paper discusses a fundamental issue not addressed in Camus’ theorem in the context of higher order curvature theory. Following the Aronhold–Kennedy theorem, in a single degree-of-freedom three-body system, the three instant centers must lie on a straight line. This paper proposes that if the line of the three instant centers is stationary (i.e., slide along itself) on the line of the instant centers, a point embedded on a body traces a pair of conjugated curves on the other two bodies. Another case is that if the line of the three instant centers rotates about a stationary point, the stationary point embedded on a body also traces a pair of conjugated curves on the other two bodies. The paper demonstrates the use of instantaneous invariants to synthesize such a three-body system leading to a conjugate curve-pair generation. It is a supplement or extension of Camus’ theorem. Camus’ theorem may be regarded as a special singular case, in which all three instant centers are coincident.


2021 ◽  
Vol 159 ◽  
pp. 104258
Author(s):  
Jeonghwan Lee ◽  
Lailu Li ◽  
Sung Yul Shin ◽  
Ashish D. Deshpande ◽  
James Sulzer

2014 ◽  
Vol 567 ◽  
pp. 499-504 ◽  
Author(s):  
Zubair Imam Syed ◽  
Mohd Shahir Liew ◽  
Muhammad Hasibul Hasan ◽  
Srikanth Venkatesan

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.


Sign in / Sign up

Export Citation Format

Share Document