Accession Number : ADA605601


Title :   Failure in Three-Dimensional Woven Composites Subjected to Quasi-Static and Dynamic Indentation


Descriptive Note : Final rept. 1 May 2008-30 Apr 2013


Corporate Author : FLORIDA UNIV GAINESVILLE


Personal Author(s) : Sankar, Bhavani V ; Subhash, Ghatu


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA605601


Report Date : 12 Sep 2013


Pagination or Media Count : 7


Abstract : Angle-interlock 3D woven composite specimens were tested under quasi- static and dynamic loads using a Hopkinson pressure bar to determine the effect of loading rate on damage evolution. The equilibrium condition in the composite specimen under dynamic loads was verified using FE analysis of the experiment. A high speed camera was used to capture delamination initiation and propagation during the experiments. The apparent inter-laminar shear strength and the bending stiffness increased with rate of loading. The damage propagated at a steady rate during quasi-static loading. The high rate of energy input during dynamic loading resulted in a rapid propagation of damage and a subsequent loss of stiffness in the composite. Delamination initiation and propagation in plain woven laminates and 3D orthogonal woven composites during short beam shear tests were analyzed using FEA. Two kinds of 3D woven composites, bound with single and double z-yarns, were considered. The FE models were guided by experimental observations from SBS tests on the same materials. . A series of mechanisms including creation and evolution of matrix cracks and delaminations were modeled discretely. The force-displacement curves obtained from the simulations were compared with experimental results. 3D woven composites with double yarns showed better damage tolerance.


Descriptors :   *COMPOSITE MATERIALS , *DYNAMIC LOADS , DAMAGE , DELAMINATION , EQUILIBRIUM(GENERAL) , FINITE ELEMENT ANALYSIS , LAMINATES , SHEAR STRENGTH , SHEAR TESTS , STATIC LOADS , STEADY STATE , STIFFNESS , THREE DIMENSIONAL , WEAVING


Subject Categories : Laminates and Composite Materials


Distribution Statement : APPROVED FOR PUBLIC RELEASE