DYNAMIC MODELING AND SIMULATION OF FLEXIBLE CABLE WITH LARGE SAG

Discrete model of flexible cable with large sag is established by using multiple rigid body-spherical hinge model, and dynamic equation of that discrete model is derived according to dynamics theory of multiple rigid body system. Displacement and velocity of system are revised to eliminate violation phenomenon of the differential-algebra equation in numerical simulation based of the theory of generalized inverse of matrices. Numerical simulation proves the validity of our method.

INFLUENCE OF GAPS BETWEEN 3-D MULTIPLE FLOATING STRUCTURES ON WAVE FORCES

In the present investigation, influence of gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. The resonant wave number is also proved to be around kL=nπ(n=1, 2, …, ∞) with a corresponding frequency shift. A small yet finite gap width will also give influence on the resonant frequency and resonant amplitude of the wave forces, but when the distance between two aligned box-shaped floating bodies becomes big enough, the hydrodynamic interaction can be neglected. The strong hydrodynamic interaction feature has its own important practical significance for the design of module structures and the links (connection) in the whole floating body system. Moreover, the importance is closely related to the hydro-elasticity analyses of a multiple box-shaped floating body system, in which local loads may be as important as the integrated loads.

A TIME DOMAIN INVESTIGATION ON THE HYDRODYNAMIC RESONANCE PHENOMENA OF 3-D MULTIPLE FLOATING STRUCTURES

A 3-D time domain method is developed to investigate the gap influence on the wave threes for 3-D multiple floating structures. Special hydrodynamic resonance due to small gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. By comparison with the results from the frequency domain technique, the results obtained from the time domain method reveal the similar resonant phenomena and hydrodynamic interaction. The resonant wave numbers are also proved around kL-nπ （n = 1,2 ……∞） with a corresponding frequency shift. The strong hydrodynamic interaction feature is practically significant for the design of module structures and the links （connection） in whole the floating body system.

THE RADIATION PROBLEM OF MULTIPLE STRUCTURES WITH SMALL GAPS IN BETWEEN

Influence of gaps on hydrodynamic interactions of multiple floating structures is considered in the present investigation. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have showed the existence of the sharp peak force response on each floating body at some special resonant wave numbers, which are also proved to be around kL =nπ （n= 1, 2, ...,∞） with a corresponding frequency shift. Width and depth of a gap also give influences on the resonant frequency and resonant amplitude of added mass and damping forces due to the radiation motions of the multiple bodies. The strong hydrodynamic interaction feature may have a big influence on the integrated loads of multiple floating structures system.

A NOTE ON THE NARROW OPEN CHANNEL RESONANCE

A narrow open channel resonant phenomenon, newly found by the authors in corresponding numerical calculations , was proved to exist based on the method of matching asymptotic expansions for three different channel configurations. It is shown that the resonant wave numbe rk emerges around kL=nπ, n=1,2,3,…∞ with a corresponding frequency s hift, where L is the length of the channel. It is also clear that the resona nce in a narrow open channel is an essential property of a channel as long as it is uniformly narrow.

Current state and progress of research on forensic biomechanics in China

Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has constituted one of the most potential research areas.in this review,we introduce how finite element techniques can be used to simulate forensic cases,how injury criteria and injury scales can be used to describe injury severity,and how tests of postmortem human subjects and dummy can be used to provide essential validation data.This review also describes research progress and new applications of forensic biomechanics in China.