Development of accurate high-speed tension test for various materials

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05984
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Osaka Prefecture University
• Principal Investigator: Umeda Tsutomu 大阪府立大学, 工学(系)研究科(研究院), 准教授 (60305646)
• Project Period (FY): 2016-10-21 – 2020-03-31
• Keywords: 引張型ホプキンソン棒法試験機 / DIC法 / ひずみ速度依存性 / 試験片形状・寸法

Outline of Final Research Achievements

In a typical high-speed tension test using the Hopkinson bar method, the digital image correlation (DIC) method was also applied to image data that were shot by the high-speed camera, and strain gauges were also attached to the test piece to directly measure stress and strain. Then, the stress-strain relationship was evaluated using the data, which were obtained by DIC method and direct measurement, together with those obtained by the conventional Hopkinson bar method, and it was compared with that obtained by the conventional method only. The possibility of accuracy improvement by using DIC method and direct measurement together, further problems and those improvements were discussed from the viewpoint of the proposed method. Appropriate test piece shapes and dimensions were also examined, and furthermore the proposed method was applied to nonferrous metals and resin materials other than iron.

Free Research Field

固体力学、衝撃工学

Academic Significance and Societal Importance of the Research Achievements

材料の高速変形挙動の正確な計測は、自動車等の機械部品のCAE解析におけるひずみ速度依存性を含めた材料の変形応答を表す構成式／材料モデルの構築に必要となる。一方、ホプキンソン棒法による代表的な高速引張試験は、準静的試験と比べて試験条件の微妙な差異により結果が異なり易く、申請時点では標準化されていなかった。このため、問題点を突き詰めて計測精度を向上させるとともに、種々の材料のデータ蓄積が求められている。本研究では、近年発展の著しい高速度カメラおよびデジタル画像相関法の併用と、試験片からの直接計測による応力－ひずみ関係の精度向上を検討し、さらに鉄以外の非鉄金属および樹脂材料にも提案手法を適用した。