Research on determining solid structure critical load and failure mode

Structural failure process and failure mode are two important issues that a lot of attentions has been paid in structural failure analysis. It has been revealed that the structure failure is mostly started from local material level, and then developed to global destruction. The failure process is inherent with the multiscale effects, and there could be varies failure modes in the process. A characteristic failure curve could reflect the failure process and the singular point of the curve indicates the change of system status. To obtain the local information of the characteristic failure curve, the wavelet multiscale method is adopted for analyzing. With the local extreme value of wavelet coefficients in each scale, the singularity point of the curve can be figured out and correspondingly the structural critical load is determined. Furthermore, by defining an index called the Failure Extent Index (FEI) Fm, the incremental ratio of plastic energy and elastic energy, two mainly failure modes, namely the progressive and catastrophic, are studied. Analysis results show that the proposed method, with strict mathematic theory basis, could capture the local feature of failure curve, and could obtain the critical load accurately. Besides, by analyzing the variation tendency of the index Fm, the failure mode can be determined. The proposed method for determining the critical load and failure mode for solid structure can provide some valuable information for the structure and the obtained results are available for further analysis and practical operation.