多重化FBG光ファイバセンサの動ひずみ計測によるCFRPフォームコアサンドイッチ構造の衝撃同定

摘要

This study established a fiber-optic-based impact identification technique for carbon fiber reinforced plas­tic (CFRP) foam-core sandwich structures. Multiplexed fiber Bragg grating (FBG) sensors were embedded between the CFRP facesheet and the foam core, and measured dynamic strain values were utilized for predicting impact location and load history. In general, low-velocity impact loading, inducing barely visible impact damage (BVID) in practical application, has long impact duration. Thus a straightforward identification technique was proposed based on an as­sumption that the deformation of the impacted structure can be considered quasi-static. This study began by evaluating measurement accuracy of multipoint dynamic strain sensing system consisting of the multiplexed FBG sensors and an arrayed waveguide grating (AWG) filter. Impact identification test was then conducted using a CFRP foam core sand­wich panel, confirming that impact location and force history can be predicted with satisfactory accuracy by using the proposed fiber-optic-based technique.%炭素繊維強化プラスチック（Carbon Fiber Reinforced Plastic：CFRP）積層板は炭素繊維にプラスチック材料を 含浸させ硬化した複合材料である．従来金属材料と比較し て機械的特性に優れるため，航空機一次構造部材への適用 が進んできている．そうしたなかCFRPの優れた特性をさ らに引き出すことが可能な新たな構造様式として，フォー ム（発泡）コアサンドイッチ構造（第1図）が注目されて いる卜3）．CFRPフォームコアサンドイッチ構造は，2枚の CFRP表皮で硬質発泡コアを挟み構造効率を上げたもので あり，表皮が面内荷重および曲げモーメントを分担し，一 方のコア材が2枚の表皮間距離を適切に保つと同時にせん 断荷重を受け持つ．