© 2015 The Authors.Abstract This paper addresses the effect of temperature on the mixed-mode interlaminar fracture toughness and fatigue delamination growth rate of a carbon-fibre/epoxy material, namely IM7/8552. Quasi-static and fatigue characterisation tests were carried out at -50 °C, 20 °C, 50 °C and 80 °C, using asymmetric cut-ply coupons. The experimental results show that temperature may have an accelerating or delaying effect on delamination growth, depending on the loading regime, i.e. either quasi-static or fatigue. Fractographic examinations were also carried out in order to assist the interpretation of the experimental data. A semi-empirical equation is introduced to describe the experimentally observed fatigue delamination growth rates at elevated temperatures

The characterization of mixed-mode fracture toughness and fatigue delamination growth in fibrereinforced composites is crucial for assessing the integrity of structural elements in service. An asymmetric cut-ply coupon (ACP) loaded in four-point bending is here proposed to carry out the aforementioned characterisations. Analytical expressions of the energy release rate and mode-mixity for the ACP are derived and validated by means of finite element analysis. A fracture toughness and fatigue characterisation of the carbon/epoxy material IM7/8552 is carried out via ACP specimens. It is proved that the material data obtained from ACP specimens match those generated using ASTM standard mixed-mode bending (MMB) coupons. The main reason for the introduction of the ACP test resides in its applicability to characterisation scenarios where measuring the delamination length with optical means, as required for MMB coupons, is difficult. Such scenarios include the investigation of static and fatigue delamination growth at low and high temperatures, which requires the usage of environmental chambers. This poses significant constraints in terms of volume available for the test rigs, and, most importantly, limitations on visual access to observe delamination propagation.However, the manufacturing of ACP coupons is more complex than for MMB specimens and the testing requires several additional precautions that are here discussed in detail.

<p>Deep-sea oil releases from accidents during offshore exploratory drilling or production are of particular concern, as the potential for such accidents increases with the expansion of the offshore industry to more extreme environments. During the 2010 Deepwater Horizon, huge amounts of oil were released into the Gulf of Mexico, adversely affecting marine wildlife. What prevented a worse outcome was the ability of nature to biodegrade oil.  </p><p>To this end, the community oi spill model MEDSKIL-II has been modified to incorporate biodegradation kinetics of dissolved oil and oil droplets dispersed in the water column. Biodegradation of oil can be modelled by Monod kinetics or as a first order decay process. The kinetics of oil particles size reduction due to the microbe-mediated degradation at water-oil particle interface is represented by the shrinking core model. Furthermore, a Lagrangian plume module has been developed and coupled to MEDSLIK-II, for predicting the fate of the spill until reaching the sea surface. The Lagrangian plume model is represented by elements that trace the plume’s trajectory. Each Lagrangian element represents a mixture of water, oil and gas. Changes in the mass and composition of the element are accounted for by the turbulent entrainment of ambient water, leakage of gas bubbles and oil droplets from the plume, dissolution of gas in seawater, and formation or disintegration of gas hydrates. The motion of the element is computed from the conservation equations for mass, momentum, and buoyancy. Biodegradation kinetics are also represented in the model, to enhance prediction of fate and transport of deep-sea spills.</p><p>A novel sampling apparatus was designed for the collection of indigenous microbial populations from the deep Eastern Mediterranean Sea, maintaining <em>in situ</em> pressure throughout the entire process of retrieval and experimentation to determine microbial oil degradation. Seawater samples were collected on board the R/V Aegaeo (Hellenic Centre for Marine Research) on 2-29-2020, off Southeast Crete, Greece. The High Pressure (HP) Sampler collected seawater between 600 to 1000 m depth. A known volume of the collected sample was transferred via a piston pump, without pressure disruption, into a HP-Reactor, at 10 MPa pressure and was incubated with crude oil at plume concentration for 77 days at <em>in situ</em> temperature (14<sup>ο</sup>C). Iranian light crude oil bioremediation was monitored for 35 days, and then the effect of dispersant addition (1:25 v/v COREXIT 9500) was observed until day 77. Kinetic analysis was used to estimate the degradation rates of hydrocarbon compounds, which were incorporated into the integrated modified MEDLSLIK-II model to simulate the effect of biodegradation on the fate and transport of subsurface spills for the Sea of Crete. Several scenarios have been considered to include the different laboratory data and oceanographic fields (water density, currents) for the area. To our knowledge, this is the first modelling effort incorporating area-specific data for biodegradation capacity of hydrocarbon degrading consortia to predict the fate of deep-water oil releases in the Eastern Mediterranean Sea.</p><p><strong>Acknowledgement: </strong></p><p>This research was funded by the GSRT and HFRI projects DEEPSEA, GA No 1510 and HEALMED, GA No 1874.</p>