A MIXED NUMERICAL EXPERIMENTAL TECHNIQUE FOR THE NONDESTRUCTIVE IDENTIFICATION OF THE STIFFNESS PROPERTIES OF FIBER-REINFORCED COMPOSITE-MATERIALS/

The characterization of the stiffness properties of fibre reinforced c omposite (FRC) materials presents more difficulties than the character ization of traditional isotropic materials. This paper first describes the difficulties that can arise and next presents a nondestructive me thod that offers a possible solution to the problems. The proposed met hod is a so-called 'Mixed Numerical/Experimental Technique' (MNET). Fr om an experimental point of view, the method requires the measurement of resonant frequencies of freely suspended rectangular test plates. F rom the numerical side, an accurate model of the test plate must be av ailable. The stress field associated with the different resonant frequ encies is multi-axial. The measurement procedure however is very simpl e and requires little specimen preparation. The equipment is inexpensi ve and the measurement procedure can be controlled by a PC program. Th e proposed MNET allows the simultaneous determination of all the aniso tropical properties and provides an estimation of their statistical di stribution. (C) 1997 Elsevier Science Ltd.