Accession Number : ADA305213

Title :   Delamination Growth Analysis in Quasi-Isotropic Laminates under Loads Simulating Low-Velocity Impact,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Shivakumar, K. N. ; Elber, W.

PDF Url : ADA305213

Report Date : JUN 1984

Pagination or Media Count : 27

Abstract : A geometrically nonlinear finite-element analysis has been developed to calculate the strain energy released by delaminating plates during impact loading. Only the first mode of deformation, which is equivalent to static deflection, was treated. Both the impact loading and delamination in the plate were assumed to be axisymmetric. The strain energy release rate in peeling, G1, and shear sliding, G2, modes were calculated using the fracture mechanics crack closure technique. Energy release rates for various delamination. sites and locations and for various plate configurations and materials were compared. The analysis indicated that shear sliding (GII) growth. The analysis also indicated that the midplane (maximum transverse shear stress plane) delamination was more critical and would grow first before any other delamination of the same size near the midplane region. The delamination growth rate was higher (neutrally stable) for a low toughness (brittle) matrix and slower (stable) for high toughness matrix. The energy release rate in the peeling mode, GI, for a near-surface delamination can be as high as 0.5G2, and can contribute significantly to the delamination growth.

Descriptors :   *LAMINATES, *FRACTURE(MECHANICS), *DELAMINATION, STRESS STRAIN RELATIONS, MATHEMATICAL MODELS, THICKNESS, STRESS ANALYSIS, FINITE ELEMENT ANALYSIS, STATIC LOADS, DEFORMATION, TOUGHNESS, MATRIX MATERIALS, ENERGY TRANSFER, STRAIN RATE, IMPACT STRENGTH, LOW VELOCITY, CRACK PROPAGATION, BRITTLENESS, PLATES, SHEAR STRESSES, FLEXURAL STRENGTH, BUCKLING, AXISYMMETRIC, NONLINEAR ANALYSIS, COMPRESSIVE STRENGTH, SLIDING, BENDING STRESS.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE