Experiments with a vertical, flexible, and submerged cylinder were carried out to investigate fundamental aspects of risers dynamics subjected to harmonic excitation at the top. The flexible model was designed aiming a high level of dynamic similarity with a real riser. Vertical motion, with amplitude of 1% of the unstretched length, was imposed with a device driven by a servomotor. Responses to distinct exciting frequency ratios were investigated, namely, ft:fN,1 = 1:3; 1:1; 2:1, and 3:1. Cartesian coordinates of 43 monitored points positioned all along the span were experimentally acquired by using an optical tracking system. A simple Galerkin's projection applied for modal decomposition, combined with standard Mathieu chart analysis, led to the identification of parametric resonances. A curious finding is that the Mathieu instability may simultaneously occur in more than one mode, leading to interesting dynamic behaviors, also revealed through standard power spectra analysis and displacement scalograms.
Experiments with a flexible and submerged cylinder were carried out to investigate fundamental aspects of risers dynamics subjected to harmonic excitation at the top. The flexible model was designed aiming a high level of dynamic similarity with a real riser. Vertical motion, with amplitude of 1% of the unstretched length, was imposed with a device driven by a servomotor. Four values of the ratio between the exciting frequencies and the first eigenfrequency were investigated, namely ft: fN,1 = 1 : 3; 1 : 1; 2 : 1 and 3 : 1. Cartesian coordinates of 43 monitored points positioned all along the span were experimentally acquired by using an optical tracking system. A simple Galerkin’s scheme applied for modal decomposition, combined with standard Mathieu chart analysis, led to the idenfication of parametric resonances. A curious finding of this paper is that the Mathieu instability may simultaneously occur in more than one mode, leading to interesting dynamic behaviors, also revealed through standard power spectra analysis and displacement scalograms.
One of the foundations for Industry 4.0 is the integration of various industrial elements (i.e. sensors, machines, and services) so that these devices can decide in a relatively autonomous way the level of integration which will be adopted. Thus, it is important to understand how the communication Machine to Machine is effectively realized and how these data can be explored and used to enhance the manufacturing process. The exchange of information between machines in the industrial process represents a potential to acquire and analyze a mass of data characterized as "big data", which can be perceived as an opportunity to discuss the paradigms of the industrial systems. Therefore, the purpose of this research is to identify the requirements for the Machine to Machine communication and the use of this data/information for more complexes analyzes using big data and analytics techniques. The KAOS methodology was utilized to model these requirements.
Umbilical cables are essential elements of offshore floating production systems. Due to their complexity, the offshore industry regularly counts on numerical tools to perform design assignments. One of these assignments is to evaluate strains and stresses states in all components due to distinct sets of external loads. The main purpose of this paper is to present a numerical model for prediction of the stress and strain fields in the umbilical cable components under crushing loads. Such loads, outcoming from the laying operation, comprise the caterpillar shoes load and the squeezing effects, associated not only to the tensile armours, but also to helical components under tension. The referred model comprises a joint analysis using a two-dimensional Finite Element Method (FEM) fed by an analytical model, which represent three-dimensional effects. A combined analytical-numerical approach is much easier to implement than a complete fully three-dimensional one and it is meant to obtain results efficiently, without the need of a large computational capacity. The paper presents and discuss modeling hypotheses and methodology, describing in which way three-dimensional effects and interactions among cable components were treated. Case studies with three umbilical cables are presented.
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