Aircraft As A Whole Spar Structure Damage Tolerance Testing And Analysis

Large integral structures replace the traditional riveted combined structures is a trendy in aircraft structure research nowadays.The integral structures have some advantages of good loading ability, low structure weight, simple machining technology, few place of stress concentration and potential fatigue crack source. On the premise of the same material function and the same weight, the integral structures can lower the manufacturing costs enormously comparing with riveted combined structures. But it is well known that the integral structures have some deficiencies, for example, the disrepair safety characteristic of this kind of structure is weak and forms widespread fatigue damage much easy because of lacking of the rivet which is the "natural" crack arrested component. For this reason, in recent years the damage tolerance characteristic of integral structures becomes the new attention problem in the field of engineering, especially the aviation engineering.In this paper, damage tolerance characteristics are studied by experiment and theory analysis based on the wing beam integrated structure of the new turbofan jet airplane.Firstly, crack propagating experiment residual strength experiment and rupture of the experiment structure are researched.Secondly, using the engineering analysis software ANSYS, stress intensity factor of the wing beam integrated structure are analyzed. The stress intensity factor differences are disused, due to the different cracks track which propagate either according to the straight line, or according to the true experiment track ,or according to the biggest pull stress theories estimated track. The influence to stress intensity factor is analyzed from the hole edge crack of skin or from beam plate thickness or from the ratio of high and thick of the stopping-crack stringer under the same weight. Crack propagating track are studied through the biggest pull stress theories and compared with the experiment track.