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Von Mises Stress (MPa) contours for various porosity and load history points


➤ to harsh, extreme environments that cause materials to go beyond their linear elastic limit. Complex degradation and damage mechanisms start to play an important role on the material performance.’ Castro continued: ‘For these scenarios,


robust simulations that can take into account the sources of non-linearity are necessary to obtain reasonably accurate results. Sometimes the sources of non-linear behaviour are found at the microstructural level, such as material defects and micro-cracking.’ ‘Tese small details make a significant


difference to failure prediction, but accounting for them directly in a single mesh requires a level of refinement that is computationally unfeasible, even with HPC hardware,’ Castro explained. Tis is where multi-scale technology


can be of most benefit, as the use of many smaller models to complete the same tasks as that of a single larger model reduces the computational complexity, reducing the time to derive meaningful results from the simulation data. Castro said: ‘It has


24 SCIENTIFIC COMPUTING WORLD


become very popular, the employment of multi-scale technology, as a way to tackle the design complexities without the expected computational overhead, by substituting an over-refined single FE model by multiple, interconnected coarser FE models representing different length scales. Te computational gains of such approach can reduce computational time from hours to minutes, without loss of accuracy or flexibility.’


Composite materials Another aspect of FEA soſtware that, according to Castro has gained significant traction in the oil and gas sector is the design and analysis of composite structures. Castro said: ‘Composites can be tailored to specific applications, and have properties that are very attractive to this industry, such as: high specific strength; high stiffness; great fatigue performance; high thermal insulation; and corrosion resistance.’ As exploration and production of oil and gas moves into deeper water, weight,


cost, and reliability of components that are sensitive to the depth of the water become increasingly important. ‘A great example of such an application in this industry is carbon- epoxy composite riser joints, designed for production and drilling operations in deep waters’ said Castro. He continued: ‘Tey can be 50 per cent and


30 per cent lighter than steel and titanium risers, respectively.’ Despite their advantages, composites fail very differently than metals due to the complex structures involved. Tis necessitates a much deeper understanding of the material structure and the interactions on a micro-structural level. Castro said: ‘Tere are multiple competing


micro-scale damage mechanisms such as fibre braking, resin cracking, and fibre-resin deboning. Tere is also a wide range of material design possibilities. All of these micro-level aspects affect the macro-structural performance, and can be efficiently modelled by using this multi-scale technology, leading to accurate predictions, and improved designs.’


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MultiMechanics


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