STIFFNESS EVALUATION OF A METAL FRAME BY THE METHOD OF DYNAMIC TESTS

Abstract

The article presents the method for assessing bending stiffness by dynamic testing using an example of the experienced metal frame. The source of forced oscillations during dynamic tests was a modal vibration exciter in the form of a mechanical oscillator with stepwise frequency control. The results of determining the natural frequencies of the frame, the frequency of forced oscillations of the exciter and logarithmic damping decrement are shown. Dynamic force and dynamic coefficient were calculated. Stiffness evaluation of the frame elements was carried out in comparison with its theoretical value specified in the finite element model. The model was compiled in the LIRA-SAPR design software 2013. For the frame elements, the curvature of a bend shape was calculated from experimental and model data. The experimental stiffness of elements on average was 8.81% less than the theoretical. The proposed approach allows realizing non-destructive testing of a bending stiffness of a structure at the measurement site.