Vibration based damage detection in composite beams under temperature variations using Poincaré maps

In this work numerical and experimental study of the vibration of laminated beams with damage, subjected to dynamic loading and temperature variations is presented.The goal of the study is to check the applicability of the damage detection technique based on an analysis of the Poincaré maps of the beam response. The geometrically nonlinear version of the Timoshenko beam theory is used to model the beam behavior. The damage is represented as a reduction of the effective elastic modulus of the beam material in a small area of the structure. The beams are subjected to a harmonic loading, leading to large amplitude vibrations and to temperature changes. The main results are focused on establishing the influence of the damage on the vibration response of heated or unheated structures and the change in the time-history diagrams and the Poincaré maps, caused by a damage and elevated temperature. The damage detection criterion formulated earlier for nonheated plates, based on analysing of the Poincaré maps of the damaged and healthy plate, is modified and tested for the case of beams additionally subjected to elevated temperatures. The importance of taking into account the actual temperature in the process of damage detection is shown. Performed experimental tests (by an optical method) confirm the applicability and sensitivity of the proposed method.

► A numerical approach has been applied to study the geometrically nonlinear vibration of thermally loaded composite beam with or without damage.
► Computed time-domain responses have been used to analyse the behavior of either intact or damaged beams.
► A concept of damage index developed previously has been adapted and applied for damage detection and location.
► A vision based measurement technique has applied to test the suggested vibration based damage detection method experimentally.
► The numerical and the experimental results confirmed the applicability of the method.