Abstract: The effect of varying environmental conditions on the modal properties of composite laminates was
studied by experimental test s , which is vital for the safety of vibration2 based st ructural health monitoring (SHM)
and vibration cont rol techniques. The st ructure responses were measured with different temperature conditions by exciter and hammer test s. The modal parameters of composite laminates were identified by the Stochastic Subspace Identification (SSI) method. It is found that the f requencies and damping ratios have a st rong negative correlation with temperature , but no clear correlation of mode shapes with temperature changes can be observed. These experimental test result s indicate that the influence of temperature variation should be considered during the design process of st ructural health monitoring and vibration cont rol techniques in laminated composite engineering systems.