報告書番号

Q07004

タイトル（和文）

超音波探傷試験の高精度化・高効率化に活用するシミュレーションツールの開発 ―第1報 有限要素法と解析的手法を組み合わせたハイブリッド法による詳細シミュレーション手法の開発―

タイトル（英文）

Development of Simulation Tools for Improvement of Measurement Accuracy and Efficiency in Ultrasonic Testing Part 1: Development of Hybrid Approach for Accurate Simulation Based on the Combination of Analytic Solution and Finite Element Method-

概要 （図表や脚注は「報告書全文」に掲載しております）

有限要素法（FEM）を用いた超音波伝搬シミュレーションの省メモリ化及び高速化を図るために，相反定理に基づく受信波形の計算方法，ならびに周波数及び超音波伝搬モードに依存しない新たな無反射境界を考案し，幾何光学理論を併用したハイブリッド法を開発した．垂直探傷及び斜角探傷を対象とした場合でも，ハイブリッド法で予測されたエコーは実験結果と良く一致した．また，ハイブリッド法で得られた複雑なき裂のBスコープ画像はFEMと良く一致した．これらのことから，超音波探傷試験を対象とした波動解析において，開発したハイブリッド法はFEMと同様に十分有効であることを確認できた． ハイブリッド法とFEMのみで計算した場合の計算時間および記憶容量を比較した結果，ハイブリッド法はそれぞれFEMの1/10および1/3程度であった．

概要 （英文）

In order to simulate wave propagation with small memory and high speed, a hybrid numerical method is developed in this report, which combines geometry theory and the finite element method. Two main problems have to be solved for this hybrid method, which are absorbing boundary conditions (ABC) and the prediction of received signals. First of all, a novel ABC called viscous-type perfectly matched layer (VPML) is proposed, which is verified by wave propagation at different directions, frequencies and wave modes. Numerical results show that the VPML is independent of propagating direction, frequency and wave modes. Then, an approach based on reciprocal relation is proposed to calculate received signals. Various received signals are computed by the hybrid method, which are compared with those by experiment. The comparison shows that received signals predicted by the hybrid method are in excellent agreement with those by experiment. Finally, a side view of a specimen with complicated stress corrosion cracks is calculated by the hybrid method, which is in good agreement with that computed by FEM. The number of nodes and computation time for this calculation by the hybrid method reduce to 1/3 and 1/10, respectively, compared with FEM. The results show that the hybrid method is available to simulate wave propagation as FEM, but with small memory and short time.

報告者

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