Detection of Rib Fractures in Advanced Grid Structure by Monitoring of Static Strain Distributions
- Paper number
IAC-05-C2.4.11
- Author
Mr. Masataro Amano, University of Tokyo, Japan
- Year
2005
- Abstract
Carbon fiber reinforced plastic (CFRP) is one of the most attractive materials to construct a light weight structure because of its high specific strength and modulus. Especially, grid structure consisting of trusses whose ribs are made of CFRP unidirectional laminates are recently considered as the effective structures in the aerospace field. This structure is called advanced grid structure (AGS). The AGS has the following advantages: (1) Since ribs are only subjected to axial forces, the weakness in the transverse direction of the CFRP unidirectional laminates is negligible. (2) The AGS is a damage tolerant structure, because the fracture of a rib does not lead the ultimate fracture of whole structure. Taking advantage of these properties, AGS has been applied to space structures. In this research, the authors attempt to identify damage location and magnitude in the AGS by the evaluation of static strain distribution with embedded FBG sensor network. By the construction of this structural health monitoring system, AGS will be high reliable, lighter and low-cost. At first, low velocity impact tests were carried out in order to clarify the types of damages caused in the rib of AGS. The results of the tests showed that fiber breakage was the only type of damage. Secondly, one point bending tests in four different loaded locations were conducted for the identification of damage location. The difference between the strain distribution with no damage and that with some damages was evaluated. The results revealed that damage location in AGS was identified by the measurement of spatial strain distribution. On the other hand, finite element analysis (FEA) was also conducted in order to discuss whether this identification technique could be applied to several locations and numbers of damages. According to the results of the FEA, it was found that at least two damages could be identified and distinguished by this identification technique in any damage locations. Moreover, in addition to the measurement of macroscopic strain distribution, microscopic strain distributions in each rib were also measured with an attached chirp FBG sensor in order to detect the magnitude of rib fracture. The result of the test suggested that the measurement of the shape deformation of the reflection spectrum from the FBG sensors enabled the identification of damage magnitude.
- Abstract document
- Manuscript document
IAC-05-C2.4.11.pdf (🔒 authorized access only).
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