Experimental studies on distribution of energy release rate among branch cracks in rapid crack bifurcation

2014 Fiscal Year Final Research Report

• Project/Area Number: 24560097
• 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: Toyohashi University of Technology
• Principal Investigator: SUZUKI Shinichi 豊橋技術科学大学, 工学(系)研究科(研究院), 教授 (60135415)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 破壊 / き裂 / エネルギー解放率 / 応力拡大係数 / 開口変異 / 衝撃工学 / 分岐 / 光計測

Outline of Final Research Achievements

High speed holographic microscopy was applied to take microscopic photographs of rapidly bifurcating cracks in PMMA or Homalite 100. The crack speed was more than 400m/s. On the photographs, crack opening displacement (COD) of two branch cracks was measured and energy release rates of the branch cracks were obtained from the CODs. The measurement results said that the distribution of energy release rate between the two branch cracks was 55% and 45% on the average.
Optical interferometry was also applied to the same bifurcating cracks to measure the singular stress field in the vicinity of the tips of branch cracks. The measurement of the singular stress field was also able to give the energy release rates of the two branch cracks. Each of them were 55% and 45% of the total energy release rate on the average.
The above results might say that there exists small asymmetry on the distribution of energy release rate between two branch cracks after the rapid crack bifurcation.

Free Research Field

高速力学・光計測