2016 Fiscal Year Research-status Report
Development of high-accuracy and large-view-field deformation measurement technique to investigate micro-nano-scale deformation distributions around interfaces
| Project/Area Number |
16K17988
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
王 慶華 国立研究開発法人産業技術総合研究所, 分析計測標準研究部門, 研究員 (20726856)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Keywords | Deformation measurement / Strain distribution / Stress concentration / Moire technique / Image processing / Phase analysis / CFRP / Interfacial damage |
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| Outline of Annual Research Achievements |
Aiming at understanding the failure mechanisms, in this year, the principles of two novel moire methods were proposed for high-accuracy and large-view-field deformation measurement (HLDM). The research results were presented in several patent applications, journal papers, conference proceedings and presentations.
The detailed achievements are as follows:
(1) The second-order moire method was proposed by integrating the scanning and sampling moire methods to achieve HLDM. The strain accuracy is 10 times higher than the scanning moire method because phase analysis is adopted. The field of view can reach 100 times wider than the sampling moire method as the grid needs not to be observed. The strain measurement accuracy was verified from simulations and experiments of Al.
(2) The reconstructed multiplication moire method was developed to realize simple 2D measurement without rotating the specimen and scanning twice. Both the displacement and strain sensitivities are twice as high as in the traditional 1D and developed 2D scanning moire methods. The effectiveness was verified from experiments under a laser and an electron scanning microscopes. The strain distributions of a carbon fiber reinforced plastic (CFRP) under three-point bending were measured.
(3) A mini-fatigue device which can perform three-point bending and tensile tests was designed. The fatigue cycle number can be greater than 1E6 and the load can reach 2000 N. It has been confirmed the grid images on the CFRP surface can be recorded under the laser microscope during the fatigue test.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
This study is to develop an optical deformation measurement technique for accurately investigating the micro-nano-scale strain distributions around interfaces in a large field of view. In the proposed research plan, the research contents in the first year include developments and verifications of HLDM and simple 2D deformation measurement methods, and the preliminary work of grid fabrication on the CFRP specimen.
About the development of HLDM, the second-order moire method was developed and verified which conforms to the research plan.
About the development of simple 2D deformation measurement, the plan was to develop a 2D scanning moire method. Actually, the 2D scanning moire method was developed between the budget application and the beginning of FY2016. A simper 2D method, i.e., the reconstructed multiplication moire method was developed and verified for simple and high-sensitivity 2D deformation measurement which is better than the planned result. The deformation measurement sensitivities are twice as high as in the 2D scanning moire method.
With regard to preliminary work of grid fabrication, 3.0μm pitch grid was successfully fabricated on CFRP specimens. Some preliminary three-point bending tests to CFRP were carried out, and strain distributions of CFRP were measured, which is ahead of the research plan.
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| Strategy for Future Research Activity |
In FY2017, the research aims to measure and analyze the full-field micro-nano-scale strain distributions around interfaces of CFRP using the developed methods in FY2016. The strain concentration distributions can help us understand the interfacial failure mechanisms.
The detailed research plan is as follows:
(1) Fabricating micro-nano-scale grids on laminated CFRP surfaces and performing three-point bending and tensile tests using the designed mechanical fatigue device. The cycle number will be set to be 1 in one case, and 1E6 in another case. The grid images under different loads or cycle numbers will be recorded by a laser scanning microscope.
(2) Measuring the displacement and strain distributions of laminated CFRPs by integrating the developed second-order and reconstructed multiplication moire methods. Strain concentrations are expected to be observed around interfaces of CFRP. The features of strain concentrations will be used to predict occurrence of cracks and delamination for understanding the interfacial failure behaviors.
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| Causes of Carryover |
At first, the scheduled amount in the quotation file of the order for goods was equal to the contract amount of the funding. However, one company made a discount during the official purchase. When I found that there was residual amount, it was late for purchasing something in FY2016.
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| Expenditure Plan for Carryover Budget |
I am planning to purchase carbon fiber reinforced plastic specimens with different layers using the residual budget.
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Research Products
(13 results)
