Reliability of Damage Tolerance Composite Structure Using Fasteners as Disbond Arrest Mechanism

摘要: A FEA model for analyzing effectiveness of fastener as crack arrest mechanism has been built. The effect the in sliding direction (Mode II) is modeled using flexibility approach. It was shown that provide significant retardation capability all load combinations considered (axial tensile and opening moment). development analytical techniques this area important to design bonded/cocured/co-bonded composite aircraft structures. procedure assessing reliability demonstrated. probabilistic approach used because traditional damage tolerance methods metallic structures are not completely applicable Probabilistic method can a more quantitative evaluation safety structure or feature. I. Introduction HE use composites enabled bonded (or co-cured, co-bonded) structures, main advantages which reduction part counts weight. critical mode type disbond due impact damage. Complete disbonding components (e.g. skin-stringer) cause failure at structural level even though individual remain intact. Therefore, any must demonstrate fail-safety by providing adequate ensure safety. In addition, nature occurrence, methodology does apply thus unable meaningful estimate structure. Damage based on assumed defect grows known rate, with proper inspection maintenance schemes detect repair before it becomes critical. However, matrix growth practically discrete events, rendering ineffective. [1-3] developed address issue taking into account life-cycle events peak repair. This paper will practical realistic problem structures: arrestment fuselage skin-stringer fasteners. fasteners mechanism, relatively understudied area, be analyzed deterministic means. component, assembly, evaluated goal analysis needed evaluate tolerant II. Fastener Effectiveness Disbond Arrest Mechanism Bonded (co-cured, co-bonded bonded) common especially thin numerous including weight, count assembly costs. bond alone, primary path, seldom possesses necessary geometric mechanical capability. difficult when designing tolerant. geometrically complex locations skin-frame shear tie). These co-located skinstringer bond, also perform without added cost complexity alternatives such z-pin z-stitching. Mode I well understood [4] typically less problematic feature would so effective laminates fail other modes first, e.g.