Damage Behavior Of The Stiffened Plates Subjected To The Low-velocity Impact

Composite stiffened plates have widely been used in aerospace and aeronautic structures due to weight-light, their high specific strength, high specific stiffness, fatigue resistance and flexibility in design. This article mainly presents the after-impact damage of stiffened plates in three different locations and residual compression strength.The impact experiments were carried out for T300/QY8911 stiffened laminates by using drop weight impact test to estimate the damage resistance at different positions on the stiffened plates. Visual observation and ultrasonic c-scan were also employed to inspect the damage size. By comparing with the pictures of damage in three different positions, it was found that the mechanism of absorbing energy varies with the impact position, as well as the damage statements.With the technique of Tie-break in LS-DYNA, a correlated program was coded to simulate stiffened plate subjected to impact. By the impact force gained by using LSPREPOSTD software ,the deflection of structure ,the damage area and stress of plates, it is obvious to found out as follows: stiffened plate plays great role in enhancing impact resistance, and the more the position of impact close to the stiffeners, the better damage resistance is. The shape of the damage area is ellipse, with the major axes pointing to the direction of high stiffeness. By comparing the result from simulation with that from experiment, it has been verified that this model can be accurate and useable.The compressive experiments were employed in the after-impact tests to obtain damage tolerances in three different positions. If the connection between the stiffeners and the laminate are in good condition, the stiffeners could effectively resist delamination and the laminate could also prevent stiffeners from bending. If the stiffeners separated from the laminate, the stiffeners were susceptible to bending. So the strength of compression not only relates to the damage area, the influence on compressive strength of the situation that the stiffeners separate from the laminate.