Safety factor probabilistic design of composite structures based on reliability

Deterministic safety factor design is difficult to adapt to the characteristics of composite structures with many uncertainty factors and concurrent multiple failure modes, and the design results cannot quantitatively describe the level of risk. In this paper, based on the synergistic reliability analysis of multiple failure modes and the introduction of uncertainty variables such as material, design, load, and so on, the safety factor probabilistic Design(SFPD) method is proposed, in which taking the structural risk level as a constraint, the allowable failure probability is converted into a safety factor to break the correlation barriers between the safety index, safety factor, and structural design. First, the main failure modes of composite structures are considered to decompose the safety indexes, and the allowable failure probability is assigned to each failure mode; second, the reliability model of composite structures is constructed with the allowable failure probability as a constraint, combining the macro-and fine-specular failure criterion, and the ultimate load is inverted through structural optimization, to make the structure safety coefficient lower and reduce the weight of the structure under the condition of meeting the safety indexes; and finally taking the typical wall plate structure of civil aircraft as the case verification object, the weight reduction of 7% for the skin and 4% for the whole structure is realized under the premise of ensuring the structural safety, and the reasonableness and feasibility of the safety coefficient reduction from 1.5 to 1.4 are verified.