Issue << content << The Flaw Detection of Composite Superstructure for Passenger Hydrofoil by the NDT Acoustic Methods

DOI: 10.12737/ 23497

2016. Vol.19. No. 4, pp. 13–17

The Flaw Detection of Composite Superstructure for Passenger Hydrofoil by the NDT Acoustic Methods

M. E. Frantsev

Introduction. Results of examination of a pilot model of hydrofoil passenger craft topside made of polymer composite materials for delamination-type defects are presented. Defects area is measured and compared with the rated values.
Method. To ensure flaw detection, use was made of a two-level test arrangement using an acoustic impedance method, free oscillations acoustic method, and DAMI-C composite materials multipurpose inspection unit. The exact location of the defect was determined by point-to-point testing. Threshold testing using a sonic scanner produces full image of the object defective area to allow subsequent measurement of the defect areas and comparing them with those of the acceptability requirements.
Results. The amount of inspection is 100% of the topside both on the outside and inside, scanning depth - up to the light medium layer. To select optimum operation mode of the inspection unit, use was made of sample pieces with dummy defects.
Conclusions. It was confirmed that using the selected reinforcing and bonding materials was appropriate to create composite material for the hydrofoil passenger craft topside. It was also confirmed that the designed structural layout of the product and its manufacturing technology were correct. No technological defects in the places of possible generation of delamination-type defects during operation have been revealed. The examination also confirmed high efficiency of the DAMI-C inspection unit equipped with RS-1 transmit-receive transducer and a sonic scanner to carry out detection of flaws in composite body shell structures including those made in the form of a sandwich, to ensure their testing for technological internal defects of the delamination (starved spot) type.

Keywords: composite superstructure, impedance method, internal defects, delaminations.
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