Analysis of Airworthiness Requirements on Amdt.25–132 of Limit of Validity to Preclude Widespread Fatigue Damage

AbstractThis article introduces innovatory changes and background to inspections of WFD for transport category aircraft which have resulted in the amendment 25-132 of limit of validity (LOV), also indicates a proactive approach which should be taken to address WFD before WFD occurs. With regard to the amendment to regulations on WFD issued by FAA, this article analyzes and interprets the actions of the design approval holder(DAH) and the related compliance methods, focusing on the applicability of the new regulations to WFD and on the methodologies and processes for performing aircraft WFD evaluations which include the determination of inspection start points(ISP) and structural modification points(SMP), the establishment of limits of validity (initial limits and extended limits), the establishment and revision of airworthiness limitations and Airworthiness Limitations section(ALS), the compliance for part 121 and 129 operators under new regulations, etc. Then a number of new research directions are presented in this article for domestic civil aircraft structure damage tolerance design and analysis for the present and the future

Combined spontaneous symmetry-breaking and symmetry-protected topological order from cluster charge interaction

The study of symmetry-protected topological states in presence of electron correlations has recently aroused great interest as rich and exotic phenomena can emerge. Here, we report a concrete example by employing large-scale unbiased quantum Monte Carlo study of the Kane-Mele model with cluster charge interactions. The ground-state phase diagram for the model at half filling is established. Our simulation identifies the coexistence of a symmetry-protected topological order with a symmetry-breaking Kekul$\acute{e}$ valence bond order and shows that the spontaneous symmetry-breaking is accompanied by an interaction-driven topological phase transition (TPT). This TPT features appearance of zeros of single-particle Green's function and gap closing in spin channel rather than single-particle excitation spectrum, and thus has no mean-field correspondence.Comment: 7+3 pages, 7+8 figure