Vliv mechanických parametrů částicových kompozitů na stabilitu trhliny

The influence of mechanical parameters of particulate composites on the crack stability

journal article - other

Czech

Je analyzován model mechanismu pro zvýšení lomové houževnatosti částicových kompozitů s křehkou matricí. Částice vytvářejí ligametnovanou zónu a otevření trhliny je založen na podmínkce konstantnosti objemu částic při plastické deformaci. Model určitým způsobem zahrnuje vlastnosti rozhraní matrice/částice. Model obsahuje i dodatečnou podmínku kritického otevření trhliny pro přetržení můstků. Výsledná okrajová úloha je převedena na řešení singulární integrální rovnice pro otevření trhliny.

The model of reinforcing mechanism which improves the fracture toughness of brittle matrix composites reinforced by ductile particles is analyzed. The particles form a bridging zone and, thus, constrain the crack opening. The stress-crack opening displacement relationship relies upon the constant volume plastic flow of the particles. This model incorporates in a certain way also the particle/matrix interface properties. The particles are allowed to deform using several different patterns which correspond to the particular strength of the particle/matrix interface. The deformation patterns are simplified versions of those obtained using finite element computations. An additional critical crack opening displacement condition behind the crack tip is imposed. The action of the system of discretely distributed particles is replaced by the action of smeared forces. The resulting boundary-value problem is reduced to the strongly singular integral equation for the crack opening displacement. This technique is based on a mathematical formalism which involves integral equations with a stronger singularity then the Cauchy type. The improper strongly singular integrals are treated in the Hadamard sense of their finite part. After solving the boundary value problem the local stress intensity factor is calculated in the standard way. The crack extension starts when the local stress intensity factor reaches the fracture toughness of the matrix and simultaneously the crack opening displacement inside the bridging zone reaches a critical value. The fracture criteria are analyzed for several combinations of micromechanical parameters of composite system and the resistance curves are presented.

lomová houževnatost, částicové kompozity, trhlina s tvárnými můstky

fracture toughness, particulate composites, bridged cracks

URBIŠ, R., KOTOUL, M., VRBKA, J.

2002

1. 1. 2001

1210-2717

Inženýrská mechanika - Engineering Mechanics

8

2

Czech Republic

197

208

12