In this work the theoretical and practical possibility of using a new measurement technique, based on high speed thermographic acquisition systems, for the study of the dynamic response of objects has been demonstrated. This methodology has been named thermoelastic modal stress analysis (TMSA). A simple test case is used to illustrate this new measurement technique: a plastic bending beam. Excitation of the structure has been performed by band-limited noise and response is measured in terms of temperature time history on its surface on the recorded thermal film. Temperature time evolution on the beam surface is related to stress time evolution according to the thermoelastic principle, for each excited resonance frequencies. By developing a special data processing software of the thermal film the possibility to get the operational deflection mode shapes of the structure is illustrated. Temperature decrease Temperature