Abstract
The dynamic response of a composite beam laminated by different materials may differ from the beam of one material. The purpose of the present investigation was to discuss the strain behavior of laminated composite beams under impact load and to compare the experimental results with theoretical ones.
The problem considered here was the initial process of axial strain due to a lateral impact to the beam of three or five layers; it had steel layers together with one acryl resin layer at the middle, or two acryl layers with one middle steel layer.
The dynamic flexural strains in certain cross sections of the beam were measured, and the strains corresponding to the measured positions were calculated, by the classical and Timoshenko beam theories as well as the finite strip method. The following was revealed from the results:
(1) Just under the point of impact, the bending strain in the upper layer was larger than that expected from the normal distribution of strain in the cross section in the initial period of about 400-600 microseconds, and it changed to that of a natural vibration of a beam after the duration time of about 1 millisecond.
(2) The finite strip method was valid to describe the behavior in all duration times, but the classical and Timoshenko beam theories agreed only after moving to natural vibration.
