AN ESTIMATION OF STRUCTURAL INTEGRITY OF THE GFRP PRESSURE BOTTLES USING ACOUSTIC EMISSION TECHNIQUE
Keywords:
Acoustic Emission, GFRP Pressure Bottles, Structural Integrity, Empirical Relation, AE Parameters, PredictionAbstract
Acoustic Emission (AE) is an upcoming NDT technique gaining ground in different fields as an on-line monitoring method for detection, location and characterization of various kinds of active degradations. This method has also made an impact as a tool for structural integrity evaluation and failure prediction.AE technique is highly sensitive and can find out degradations in FRP structures viz delamination, fibre crack, debonding and matrix crazing etc well before occurance of any catastrophic failure under dynamic service condition. In this present study, five identical GFRP hardware were taken up for the study and acoustic emission data is analyzed thoroughly and a lucid empirical relation is being developed to predict their burst performance. In this approach the failure is significant even at 50 to 60 % of maximum expected operating pressure (MEOP) with a reasonable error margin. Till date there is no method spelt out in the open literature for burst pressure prediction of composite pressure vessels. Acoustic Emission monitoring is carried out on 6- litre capacity cylindrical GFRP pressure bottles for four identical cases. An attempt is made on the fifth hardware to predict its burst pressure. This innovative methodology illustrates the structural behavior of GFRP pressure bottles in terms of AE parameters and its derivatives. In this approach AE data is acquired only upto 50% of the theoretical burst pressure and then the bottles are pressurized upto failure. An empirical relation was generated for the GFRP bottle which is subjected to cyclic proof pressure cum burst test on the basis of the governing AE parameters viz, count rate, duration rate, amplitude rate and felicity ratio exhibited. This methodology can possibly predict in real time the burst pressure of similar hardware if extended to other material systems
Downloads
References
Marvin and Hamstad A, (1986), “A Review –Acoustic Emission, A Tool for Composite Material Studies”, Experimental Mechanics, Vol.3, 7-13.
Gorman M R, (1990), “Burst Prediction by Acoustic Emission in Filament Wound Pressure Vessels”, Journal of Acoustic Emission, Vol.9 (2), 131-139.
Hill E V K, (1991), “Burst Pressure Prediction in 45.7cm (18 inch) Diameter Graphite/ Epoxy Pressure Vessels using Acoustic Emission data”. Proceedings of the 36th International SAMPE Symposium and Exhibition, Covina, California, Vol.36, 272-283.
Chang R R, (2000), “Experimental and Theoretical Analyses of First-ply Failure of Laminated Composite Pressure Vessels.” Composite Structures, Vol. 49, 237-243.
David Cohen, Susan C Mantell and Liyang Zhao, (2001) “The Effect of Fiber Volume Fraction on Filament Wound Composite Pressure Vessel Strength.”Composites: Part B: Engineering, Vol. 32, 413-429.
Tae-Kyung Hwang, Chang-Sun Hong and Chun-Gon Kim (2003), “Size Effect on the Fibre Strength of Composite Pressure Vessel” Composite Structures, Vol.59, 489–498.
Ho-Sung Lee, Jong-Hoon Yoon,Jae-Sung Park and Yeong-MooYi, (2005), “A Study on Failure Characteristic of Spherical Pressure Vessel.” Journal of Materials Processing Technology, Vol.164–165, 882–888.
Kam T Y, LiuY W and Lee E T, (1997), “First-Ply Failure Strength of Laminated Composite Pressure Vessels.” Composite Structures, Vol. 38(l-4), 65-70.
Hill E V K and Lewis T J (1985), “Acoustic Emission Monitoring of a Filament-Wound Composite Rocket Motor Case during Hydro Proof’’. Journal of Material Evaluation, Vol 43(7), 859-863.
