抄録
The complex shear modulus of a thin adhesive layer may be determined by the torsional resonance tests on a composite beam with metal facings and an adhesive core. In order to determine this shear modulus by such method (Composite Beam Test Method), it is necessary to know the torsional rigidity of a three layered composite beam. This is calculated exactly herein. Torsional tests are carried out on the symmetrical elastic beams bonded by epoxy resin adhesives from -20°C to 80°C. The results obtained scatter above a transition temperature range of the adhesives. The causes of scattering are discussed theoretically based on the error analysis. It is indicated that the scattering is considerably dependent on the deviation of elastic layer thicknesses and enabled to minimize it by using the optimum test beam configuration such as the torsional rigidities elastic layers are nearly equal to those increments caused by bonding.
