NONLOCAL IN TIME MODEL OF MATERIAL DAMPING IN COMPOSITE STRUCTURAL ELEMENTS DYNAMIC ANALYSIS

In this paper the problem of numerical simulation of composite bending elements dynamic considering internal (material) damping. For this purpose the nonlocal in time damping model, called damping with memory, is proposed as an alternative to the classic local Kelvin-Voigt model. Damping with memory makes damping forces not only dependent on the instant value of the strain rate, but also on the previous history of the vibration process. Since finite element analysis is the most common method of structural analysis, the nonlocal damping model is integrated into FEA algorithm. The FEA dynamic equilibrium equation is solved using the explicit scheme. The damping matrix was developed using the stationary full energy requirement. One-dimensional nonlocal in time model was implemented in MATLAB software package. The results of three-dimensional numerical simulation of the composite beam vibration obtained in SIMULIA Abaqus were used for model calibration. The obtained results were compared to the results based on classic Kelvin-Voight damping model.

ON THE ROLL DAMPING OF AN FPSO WITH RISER BALCONY AND BILGE KEELS

Although the topic of roll damping of vessels at sea is already brought to the attention of naval architects by Froude more than 100 years ago, the physics of it remain intriguing, even today. An accurate prediction of the motions of offshore structures in harsh environments, designed for 25 years continuous operation, is the topic of this paper. Model test experiments for two FPSO’s developed by SBM for Petrobras are discussed. It is shown that the FPSO submerged riser balcony on one side of the vessel contributes to the roll damping through similar physics as the bilge keel does. Flow memory effects are discussed in detail since these are shown to have a noticeable effect on the roll damping coefficients. The paper further employs 3D CFD simulations to enhance the understanding of the fluid behaviour around the FPSO appendages, necessary to construct a rational and accurate roll damping model in the future.

Modeling and Analysis of Axial Dynamics of Cable Arrangement Device Based on MATLAB

Aiming at the current insufficient dynamic analysis of the cable arrangement device, the axial dynamics analysis of the cable arrangement device is carried out in combination with the force characteristics of the cable arrangement device. The axial dynamic model of cable arrangement device is established by using spring-damping model, and the dynamic equation is established by using Lagrange equation. The influence of system parameters of cable arrangement device on axial first-order natural frequency is analyzed by numerical method. By fitting and loading the external excitation of the cable arrangement device, the axial dynamic response of the cable arrangement device under different axial forces is obtained. Through numerical results, the influence laws of the position and mass of the traveling mechanism and the support stiffness of the lead screw on the axial first-order natural frequency are obtained, It is found that the axial displacement of the cable arrangement device under axial force is very small, and the cable arrangement device has strong retention of dynamic characteristics. The results have certain guiding significance for the structural design and application environment of cable arrangement device.