ESTIMATION OF LOW-VELOCITY IMPACT DAMAGE IN LAMINATED COMPOSITE CIRCULAR PLATES USING NONLINEAR FINITE-ELEMENT ANALYSIS

Nonlinear finite element analysis is used for the estimation of damage due to low-velocity impact loading of laminated composite circular pl ates. The impact loading is treated as an equivalent static loading by assuming the impactor to be spherical and the contact to obey Hertzia n law. The stresses in the laminate are calculated using a 48 d.o.f. l aminated composite sector element. Subsequently, the Tsai-Wu criterion is used to detect the zones of failure and the maximum stress criteri on is used to identify the mode of failure. Then the material properti es of the laminate are degraded in the failed regions. The stress anal ysis is performed again using the degraded properties of the plies. Th e iterative process is repeated until no more failure is detected in t he laminate. The problem of a typical T300/N5208 composite [45 degrees /0 degrees/-45 degrees/90 degrees](s) circular plate being impacted by a spherical impactor is solved and the results are compared with expe rimental and analytical results available in the literature. The metho d proposed and the computer code developed can handle symmetric, as we ll as unsymmetric, laminates. It can be easily extended to cover the i mpact of composite rectangular plates, shell panels and shells.