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PRODID:-//Memento EPFL//
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SUMMARY:Cancelled event - IMX Seminar Series - High-performance discontinu
 ous composites: material and structural design
DTSTART:20200518T131500
DTEND:20200518T141500
DTSTAMP:20260511T134911Z
UID:fa7309b73ea95556f85ceeb4ca4bc8b2d4805cba6a79aad500ddf37f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Soraia Pimenta\, Imperial College London\, UK\nHigh-perform
 ance discontinuous composites (also known as tow-based discontinuous compo
 sites (TBDCs)\, advanced-SMCs\, or randomly-oriented strands) are composed
  by chopped carbon-fibre tows randomly oriented and distributed in a polym
 eric matrix. This discontinuous and random microstructure allows component
 s with complex 3D shapes to be moulded using fully automated processes\, w
 ith processing times down to a few minutes. In addition\, the tow-based mi
 crostructure allows these materials to achieve a high content of carbon fi
 bres (up to 60% in volume) and\, consequently\, to achieve good mechanical
  properties. Due to this combination of manufacturability and high-perform
 ance\, TBDCs are now being used to manufacture lightweight (semi-)structur
 al components in the aeronautics\, automotive and sports industries.\nWhil
 e the multi-scale nature of the microstructure of TBDCs (reinforced at bot
 h the tow- and fibre-levels) is key for their unique combination of manufa
 cturability and performance\, it also creates two challenges for the effec
 tive use of these materials. Firstly\, it widens the design space of the m
 aterial\, since its mechanical properties are dictated not only by the fib
 re and matrix types\, but also by the dimensions of the tows. Secondly\, t
 he large dimensions of the tows (up to 50 mm long and 20 mm wide) lead to 
 significant variability of local mechanical properties (e.g. stiffness and
  strength) from one point of a component to another\; this makes TBDCs ext
 remely damage tolerant\, but it also complicates structural design.\nThis 
 talk will address these two challenges through a combination of experiment
 s and modelling. Regarding the first challenge\, we have experimentally ch
 aracterised the mechanical response of TBDCs with a range of material micr
 ostructures\, to assess the effect of tow geometry and preferential orient
 ation on the properties of the composite\; we show that the thickness (or 
 filament count) of the tows has a very significant impact on performance\,
  with thicker tows leading to a knock-down on both strength and stiffness.
  We also propose computationally-efficient models which can be used to per
 form virtual experiments\, identify optimal material microstructures\, and
  support the development of improved materials.\nRegarding the second chal
 lenge\, we have characterised the damage tolerance of TBDCs using a combin
 ation of unnotched and notched specimens\; we show that the fracture tough
 ness of TBDCs can be higher than that of continuous-fibre composites. More
 over\, notched specimens present no reduction in load-bearing capacity (co
 mpared to unnotched specimens)\, and often fail away from the notch\; this
  makes TBDCs the ultimate “damage tolerant” material\, but makes it di
 fficult to predict the behaviour of structures with complex geometries. We
  overcome this challenge by proposing a stochastic framework based on Fini
 te Element (FE) Monte-Carlo simulations\, which accounts for the spatial v
 ariability of local mechanical properties of TBDCs\, and uses non-local ho
 mogenisation criteria to predict failure in a mesh-independent way.\nBio: 
 Dr Soraia Pimenta obtained her PhD from Imperial College London in 2013\, 
 and she is now a Senior Lecturer at the Department of Mechanical Engineeri
 ng. Soraia’s research interests include developing accurate and efficien
 t models for the mechanical response of composites\, and promoting a new g
 eneration of easy-to-manufacture\, damage tolerant and sustainable materia
 ls. Soraia won the SAMPE Schliekelmann Award in 2009\, the International C
 ommittee for Composite Materials Tsai Award in 2011\, the Japan Society fo
 r Composite Materials Hayashi Memorial International Award in 2015\, and t
 he Imperial College President’s Medal for Outstanding Early Career Resea
 rcher in 2015. She has also been a Research Fellow of the Royal Academy of
  Engineering since 2015.\n 
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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