Structural Damage Detection for Plates Using Flexibility Based Strain Energy Method

Plates like structural elements are commonly found in many structural applications and may undergo injury or damages during its service life. Identification, characterization, and detection of damages at the early stages in a plate structure avoid the further growth of damages and prevent the structural failure. In this paper, the strain energy and flexibility matrix-based damage detection procedure is adopted to detect single as well multiple damages in a plate structure. Toward this, a 4-noded plate element is utilized to discretize the rectangular plate with 6° of freedom (dof) at every node. The flexibility matrix is calculated using the natural frequency and mode shape. This method detects the damage in the plate by an increase in flexibility matrix of the damaged one. The damage indicator is then computed by evaluating the changes in strain energy of a structural plate using the coefficients of the flexibility matrices. The modal parameters were extracted from the FE analysis software Abaqus. Nine illustrative examples with damages at various locations are induced by decreasing the modulus of elasticity at the specified elements in plate structure, in order to determine the effectiveness of the method. The numerical result shows that the adopted damage detection procedure can be able to locate the structural damages in plates with lower modes, and the magnitude of the evaluated damage index depends on the severity of the damage.