Abstract: The stress intensity factor and residual strength for thin-walled stiffened structures with multi-cracks of aircraft lower wing panels are obtained by using “strain gage method” and “stress intensity factor gage method”.Furthermore,based on the test results for twelve specimens (460mm×910mm) and through statistical process,the probability residual strength curves (p-σ-a) are obtained.Finally,a comparison is made between the experimental data and computed results.It shows that they are in excellent agreement.Therefore,the proposed method and numerical results can be used as an important reference in probability damage tolerance design of aircraft structures.

Key words: ribs(sapports), residual strength, probability theory