No abstract

A new donor explosive, ROWANEX 3601 has been selected for use in the large scale gap test (LSGT). It was necessary to calibrate the peak pressure recorded on the central axis of the PMMA gap using calibrated piezo-resistive pressure transducers as a function of the gap thickness. The stress history within the PMMA gap was measured and the peak pressure plotted against gap thickness as a calibration. Further effects were noted relating to the curvature of front exiting the donor charge and the validity of the measurement of the transmitted shock at small gap thicknesses.

The work described here arose from a study into explosive welding. As part of that study, the impact velocity of stainless steel and titanium plates to grazing detonation of ANFO/perlite, the velocity of detonation were measured. Computer simulation required a new model which copes with an equation of state of low explosives. The Williamsburg equation of state (WBG EoS) has several advantages over traditional equations of state, such as the Jones-Wilkins-Lee (JWL), when modelling low explosives such as ANFO. The use of the WBG EoS to model Ammonium Nitrate-fuel oil (ANFO) explosives with an inert perlite admixture is described. The WBG EoS was codified into the commercial finite difference package AUTODYN2D and used to model the acceleration of thin plates under grazing detonation, as seen in explosive welding. The predictions were verified by comparison with experiments.

The response to pure bending of tubes with rectangular cut-outs is considered. Experiments on 1000-mm long, 100-mm diameter, and 2.55-mm wall thickness DIN 2391 ST NBK supported steel tubes are described. Such a thickness-to-diameter ratio is typical of structural columns, rather than shell structures. Tubes containing cut-outs with an axial dimension of up to 30 mm and a circumferential size of up to 180° were tested. It was found that plastic hinge mechanisms dominated the response when the cut-out was on the compressive side, whereas fracture behaviour dominated the response when the cut-out was on the tensile side. Finite element and semi-empirical analyses were carried out to predict the global load-deformation behaviour of the tubes. All analyses gave reasonable predictions of the experimental results for the majority of the cut-out parameters investigated. The aim of this study is to investigate the feasibility of using cut-outs to initiate and control the toppling of offshore jacket structures.

ObjectivesTo compare susceptibility of five different stent platforms with longitudinal stent deformation (LSD) using a clinically relevant bench testing model simulating both short and long malapposed lengths.BackgroundRecent data suggest that design modifications to the Promus Element stent which led to the Promus Premier stent has reduced susceptibility to LSD. However, susceptibility to LSD at long malapposed lengths has not been tested. Furthermore, the mechanisms behind susceptibility to LSD are as yet unclear.MethodsThe Omega, Integrity, Multilink 8, Biomatrixand Promus Premier stent platforms were tested. The Omega, Integrity and Multilink 8 platforms were used in place of their drug-eluting equivalents. 3.5 mm stents were deployed in a stepped tube with the distal portion fixed and the proximal test section exposed. The force required to compress stents by a fixed distance at different exposed lengths was compared. Symmetrical and point loading were used.ResultsThe Promus Premier was longitudinally as strong as Multilink and Integrity at a short exposed length (4 mm) but weaker, in between Omega and the other platforms, at longer exposed lengths (12 mm). As previously noted, the Omega (Promus Element) platform was significantly weaker than the other stents and Biomatrix was the strongest stent.ConclusionSusceptibility to LSD varies depending on length of malapposed segment when tested using a clinically relevant model as in this study. The mechanisms behind the susceptibility are likely multifactorial, including connector number, strut thickness, connector alignment and ring orientation but remain to be elucidated.