Mechanical properties of offshoring polymer composite pipes at various temperatures

International audiencePolymer composite pipes can be exposed to the thermomechanical loading due to hot and cold fluid flow, which results in the degradation of their properties. In this paper, effect on mechanical properties of composite pipes under different temperatures ranging from −40 to 80 °C is studied experimentally. The composite pipes consist of glass/epoxy tubes having 86 mm internal diameter and 6.2 mm of thickness with ±55° glass filament winding, intended for offshoring applications. TEMA TTC machine and split disk are used for uniaxial tensile tests and the thermal aging is considered with the help of SERVONTAN climatic chamber. Thermal aging is carried out on these specimens in climatic chamber for 8 h at different temperatures and then uniaxial test is performed. Experimental results have shown degradation in the mechanical properties of polymer pipes with an increase in the temperature. For pipes at colder temperature, the rigidity of composite increases progressively with the temperature and results in drastic decrease in the displacement at break. Also there is a decrease in the yield stress and an increase in yield strain with an increase in the temperature

Numerical Evaluation of Dynamic Response for Flexible Composite Structures under Slamming Impact for Naval Applications

International audienceThe deformable composite structures subjected to water-entry impact can be caused a phenomenon called hydroelastic effect, which can modified the fluid flow and estimated hydrodynamic loads comparing with rigid body. This is considered very important for ship design engineers to predict the global and the local hydrodynamic loads. This paper presents a numerical model to simulate the slamming water impact of flexible composite panels using an explicit finite element method. In order to better describe the hydroelastic influence and mechanical properties, composite materials panels with different stiffness and under different impact velocities with deadrise angle of 100 have been studied. In the other hand, the inertia effect was observed in the early stage of the impact that relative to the loading rate. Simulation results have been indicated that the lower stiffness panel has a higher hydroelastic effect and becomes more important when decreasing of the deadrise angle and increasing the impact velocity. Finally, the simulation results were compared with the experimental data and the analytical approaches of the rigid body to describe the behavior of the hydroelastic influence

Mechanical performance evaluation of sandwich panels exposed to slamming impacts: Comparison between experimental and SPH results

International audienceSlamming is a dynamic phenomenon in which a high magnitude pulse peak pressure occurs in a short time duration when the bottom structure of a ship impacted against the sea surface. This phenomenon can cause damage in the structure due to fluid-structure interaction (FSI) thus, plays a vital role in designing and manufacturing of ships for naval applications. In this paper, high performance sandwich structure, having many opportunities and challenges for the marine structural design, were studied experimentally using a high-speed shock test machine to examine the water entry problem. In addition, a velocity control system was used to calibrate and preserve the approximately uniform velocity throughout the slamming impact. Sandwich panels with different thicknesses i.e. 27 mm and 37 mm therefore, having different stiffness's were exposed under constant impact velocities of 6 and 8 m/s at the deadrise angle 10°. Experimental results were then compared and verified by the numerical investigation based on explicit Smoothed Particle Hydrodynamics (SPH) method. This study focuses on the overall structural response, deformation, and hydrodynamic response of the structure during the dynamic impact designed for naval applications

Nutrients, trace metals and B-vitamin composition of the Moulouya River: A major North African river discharging into the Mediterranean Sea

We analyzed dissolved nutrient, trace metal and vitamin (B-vitamins and methionine) concentrations in the lower course of the Moulouya River (MR, Morocco) and its estuary. The flow of this African river has changed drastically (a reduction of almost 50%) in the last 50 years due to the regulation of the river flow through dams and alterations of the course constructed to satisfy population necessities and growing agricultural requirements. Consequently, it has produced a remarkable increase in nitrate concentrations (up to 270 μM) and alteration of N:P ratios within the river, as well as a reduction of overall P and Si efflux to nearby coastal waters. Despite the historical mining activities in the upper MR, concentrations of Pb, Zn and other metals in sediments and waters do not display significant contamination as compared with other Mediterranean rivers, mainly due to the retention by dams of upstream metal contamination. Mean concentrations of dissolved B-vitamins in the river showed lower levels (13-55% lower) than those in coastal waters and hence the river does not represent an important B-vitamin source.This work has been carried out as part of AECID funded project Quemomar (Ref: 11-CAP2-1146), the MICINN funded project MEGOCA (Ref: CTM2014-59244-C3-3-R) and the National Science Foundation Biological Oceanography grant (Ref: #1435666). A. Jordi was supported by a Ramón y Cajal contract from the Spanish Ministry of Economy and Competitiveness, S. Anglès was supported by a Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme (GA-302562), and D. Sánchez by the JAE-predoc program of the Spanish National Research Council (CSIC)Peer Reviewe