METHOD FOR DETECTING CRACK ON BEAM STRUCTURE

摘要

PURPOSE: A method for detecting cracks of a beam structure is provided to confirm stability by providing information related to a size and position of cracks generated in a coupled oscillation structure of a beam form and to reduce costs and time. CONSTITUTION: A method for detecting cracks of a beam structure is as follows. The equation of motion in which three rigidity sections caused by a moment, a shearing, torsion including the influence of cracks with respect to a beam is induced(S1). The rigidity section which is most sensitive to a characteristic frequency of the beam is selected through a sensitivity analysis of the three rigidity sections and the characteristic frequency(S2). A new rigidity K is induced by applying the influence in which the rest two rigidity sections influence to the characteristic frequency as a weighting(S3). A relational expression with respect to positions of the new rigidity K and cracks is obtained(S4). A relational expression with respect to depths of the new rigidity K and cracks is obtained(S5). The lowest three characteristic frequencies of a structure are grasped through a modal experiment(S6). The positions of the cracks and a K value are predicted by using the relational expression with respect to the positions of the new rigidity K and the characteristic frequencies(S7). The depth of the cracks is predicted by using the relational expression with respect to the depths of the new rigidity K and cracks(S8).