2. Vibration testing of beams at low and medium frequencies

2.1 Method principle

• The measurement technique involves two main steps.

  • The first step is to extract the complex stiffness characteristics from the transfer function of a vibrating beam for the three classical elementary loads: extension, bending and torsion, as shown in figure 1 . The beams are as simple as possible: flat, rectilinear or curvilinear (ring) beams whose axes are the axes of material symmetry of the orthotropic composite material, so that only one complex modulus is involved at a time. It should be noted that tests on off-axis beams have been considered (