Accession Number : ADA466507


Title :   Numerical Investigation for the Microstructural Effects on the Crack Growth Behavior of Particulate Composite Materials


Descriptive Note : Final technical rept. 23 Jun 2004-22 Jun 2006


Corporate Author : KAGOSHIMA UNIV (JAPAN) GRADUATE SCHOOL OF SCIENCE AND ENGINEERING


Personal Author(s) : Okada, Hiroshi


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA466507


Report Date : 26 JUL 2006


Pagination or Media Count : 64


Abstract : In present investigation, analyses for the damage evolution behavior of particulate composite materials by using the finite element method (FEM) and the s-version finite element method (s-FEM) were carried out. The analyses were carried out in particular interest in the phenomenon of crack propagation. Prior to crack propagation, material damage develops in the material. The material damage may be in the forms of microviod and/or microcracks in the binder (matrix) and in the form of binder (matrix)/particle separation that is known to be dewetting. In a macroscopic sense, the reinforcing particles distribute evenly in matrix. However, at microscopic level, the density of the distributed particles varies. This means that the stiffness and strength of the material also have some spatial variations. Material damages initiate at the weak material locations and then propagate the surroundings. When cracks are present in the material, the cracks interact with the surroundings and the material To simulate such scenarios, we adopted two kinds of damage constitutive models. One is isotropic damage model and the other is ?separate dilatational/deviatoric damage constitutive model? in which the contributions of hydrostatic and of deviatoric stresses are accounted for independently. A parameter in the separate dilatational/ deviatoric damage model can characterize which, hydrostatic or deviatoric stress component, has dominant influence to the damage behavior of the material. A series of analyses on uncracked and cracked specimen with statistically varying material stiffness at a microscopic level were carried out. The results revealed that the damage behavior is highly influenced by the damage mode.


Descriptors :   *COMPOSITE MATERIALS , *FINITE ELEMENT ANALYSIS , *FRACTURE(MECHANICS) , MODELS , CRACK PROPAGATION , MICROCRACKING , TENSILE STRESS , DAMAGE ASSESSMENT , NUMERICAL ANALYSIS


Subject Categories : LAMINATES AND COMPOSITE MATERIALS
      NUMERICAL MATHEMATICS
      MECHANICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE