Papers by Author: Peter Davies

Abstract: Ultra Deep offshore oil exploitation (down to 3000 meters depth) presents new challenges to offshore engineering and operating companies. Flow assurance and particularly the selection of insulation materials to be applied to pipe lines are of primary importance, and are the focus of much industry interest for deepwater applications. Polymeric and composite materials, particularly syntactic foams, are now widely used for this application, so the understanding of their behavior under extreme conditions is essential. These materials, applied as a thick coating (up to 10-15 cm), are subjected in service to: - high hydrostatic compression (up to 30 MPa) - severe thermal gradients (from 4°C at the outer surface to 150°C at the inner wall), and to high bending and shear stresses during installation. Damageable behavior of syntactic foam under service conditions has been observed previously [1] and may strongly affect the long term reliability of the system (loss of thermal properties).This study is a part of a larger project aiming to model the in-service behavior of these structures. For this purpose it is important to identify the constituent mechanical properties correctly [2, 3]. A series of tests has been developed to address this point, which includes: - hydrostatic compression - shear loading using a modified Arcan fixture This paper will describe the different test methods and present results obtained for different types of syntactic foams.

Abstract: This paper describes a technique to fabricate instrumented composite cylinders made by the filament winding process and based on the insertion of Bragg grating sensors contained in an optical fiber, so that real time monitoring of the temperature and strain response can be made. The main advantage of this method is that, for the first time, the strain response of the wound layers as a function of time and temperature can be monitored during fabrication without alteration of the composite structure, since the sensor is a filament itself. The sensor data reveals the existence of several phenomena related to the manufacturing process and material response. The results show that during the curing stage of the fabrication of the composite cylinders there is a dimensional contraction without change in temperature which indicates that a material transformation occurs, and also that at the last stage there is a residual compressive strain which may affect the in-service behavior of the composite cylinder.