Nearly mode I fracture toughness and fatigue delamination propagation in a multidirectional laminate fabricated by a wet-layup.

T. Chocron, L. Banks-Sills

Research output: Contribution to journalArticlepeer-review

Abstract

Five double cantilever beam specimens were tested quasi-statically to obtain a GIR resistance curve. In addition, nine double cantilever beam specimens were tested in fatigue to obtain a Paris-type relation to describe the delamination propagation rate da/dN where a is delamination length and N is the cycle number. Displacement ratios of Rd = 0.10 and 0.48 were used for five and four specimens, respectively. The specimens were fabricated by means of a wet-layup process from carbon fiber reinforced polymer plies. The interface containing the delamination was between a unidirectional fabric and a woven ply. The fracture toughness and fatigue delamination propagation protocols are outlined. The mechanical and thermal residual stress intensity factors were obtained by means of finite element analyses and the conservative A/-integral along the delamination front. They were superposed to determine the total stress intensity factors. It was found that the total mode I stress intensity factor dominates the other two stress intensity factors. Thus, nearly mode I deformation was achieved. Interpolation expressions for the mechanical and thermal residual stress intensity factors were determined using three and two-dimensional fittings, respectively. Results are presented with an expression for GIR determined. Moreover, the fatigue data is described including threshold values and master-curves. These results shed light on the behavior of delamination propagation in multidirectional laminate composites.
Original languageEnglish
Pages (from-to)103-134
Number of pages32
JournalFizicheskaia Mezomekhanika
Volume21
Issue number6
DOIs
StatePublished - 1 Nov 2018

Keywords

  • FRACTURE toughness
  • R-curves
  • FIBROUS composites
  • DELAMINATION of composite materials
  • STRESS intensity factors (Fracture mechanics)
  • волокнистые композиты
  • вязкость разрушения
  • кривая сопротивления
  • постоянная амплитуда
  • скорость распространения усталостного расслоения
  • constant amplitude
  • fatigue delamination growth rate
  • fiber reinforced composites
  • fracture toughness
  • R-ratio
  • resistance curve

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