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SUMMARY:The roadmap to the efficient design of composites for structural i
 ntegrity
DTSTART:20151130T140000
DTEND:20151130T150000
DTSTAMP:20260924T095029Z
UID:fb648f6071738658806df0912b673ec5b2e38f81a47d829a9b4b6698
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Carlos González & Dr. Cláudio S. Lopes\nThis presentatio
 n proposes a systematic strategy to design composite materials for structu
 ral integrity (damage resistance\, damage tolerance) using a multiscale nu
 merical approach. A virtual design/testing strategy that takes into accoun
 t the physical mechanisms of damage at the different length scales has bee
 n developed and validated and IMDEA Materials. The multiscale approach des
 cribes systematically the material behaviour at different length scales fr
 om ply microstructure to laminate\, and to composite structure.\nAt micros
 cale level\, the representation of the mechanical behaviour of a composite
  material is achieved by means of a Representative Volume Element (RVE) wh
 ich accurately describes the mechanical behaviour of the different phases 
 by means of constitutive equations. The matrix behaviour is modelled by a 
 coupled damage-plasticity law in order to handle the non-linearity due to 
 plasticity in the matrix under compressive stress states and the quasi-bri
 ttle behaviour under tensile loads. On the other hand\, a cohesive model i
 s adopted to address decohesion and friction between fibres and matrix. Th
 e relevant material properties of the matrix and interfaces are measured b
 y means of instrumented nanoindentation and direct observation of the dama
 ge mechanisms and events (Figure 1a).\nAt mesoscale level\, laminates are 
 simulated by means of thermodynamically-consistent damage models for plies
  and ply-interfaces defined in the context of the mechanics of continuum m
 edia (Figure 1b). The ply model use physically-based criteria to predict t
 he onset of matrix cracking and fibre fracture under tensile\, compressive
  and shear loadings and take into account the effect of ply thickness on t
 he strength. The model parameters (e.g. ply elastic constants\, tensile an
 d compressive strength in the longitudinal and transverse directions\, she
 ar strength\, etc.) are determined by means of micromechanical simulations
 . The interface model\, to simulate delamination and friction between plie
 s\, is implemented as a surface interaction.\nAt structural level\, the la
 minate is modelled by means of shell elements which contain as many integr
 ation points through the thickness as the number of plies in the laminate 
 in each region of the component but different plies are not modelled indep
 endently. Thus the analyses are limited to bidimensional stress states\, a
 nd do not take into account delamination\, but are very efficient from the
  numerical viewpoint and can capture the structural failure modes of large
  structures (impact\, buckling\, etc.). Nevertheless\, accurate models for
  the onset and evolution of damage at the laminate level are necessary in 
 order to ensure the fidelity of the simulations.\nBesides the simulation o
 f the actual physical mechanisms in composites\, one of the\nadvantages of
  this bottom-up multiscale approach is that changes in the properties of t
 he\nconstituents (fibre\, matrices)\, the fibre architecture or laminate l
 ay-up can be easily\nincorporated to provide new predictions of the macros
 copic behaviour of the composite.\nAlso\, the observed scatter in material
  properties can be easily studied as well as its\ninfluence on the failure
  mechanisms.\nThis presentation includes examples of the application of th
 e multiscale virtual testing\napproach such as the prediction of in-situ e
 ffects in composite laminates\; failure of openhole\nand bearing specimens
 \; low-velocity impact response of laminates (Figure 1b)\; bird\nimpact on
  aircraft leading edge (Figure 2)\; and design of non-conventional composi
 te\nlaminates.
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STATUS:CONFIRMED
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