In this study, three types of filament wound glass fiber reinforced epoxy composite specimens were tested according to the ASTM standards to evaluate preliminary, the acoustic emission wave velocity. The pipe specimens had 300.0 mm of length, 50.5 mm of diameter and 3.5 mm of wall thickness. Ten points were marked over the imaginary central circle on the pipe middle, from zero degree up to 90º with nine divisions of 10º each one and an additional point representing the crossing of plies. Next, there are positioned two collinear acoustic emission (AE) sensors along the length, positioned at 35 mm from middle, axially. After the specimen preparation, took place theHSU-NIELSENor pencil lead break (PLB) tests to analyze the signal wave time for both sensors, by means of the 0.3mm – 2H graphite lead brake. The results were compared to considering the angular variation and the velocity for each winding angle. It was evident that the procedure above can determine with good precision the variations occurred on the acoustic emission velocity on filament wound composite pipes, regarding the three angular variations compared. This study was the parameter of control to proceed with the acousticemission evaluation over tensile tests in further studies to predict the fatigue and the damage propagation on this typology of laminates.
In this work were compared two types of filament wound pipe specimens to know the variation in stress and strain regarding to the cross sectional area variation at 65° C according to the standards. The groups are named as G1 and G2, respectively with the G1 having 63.5mm of internal nominal diameter, and the G2 having 76.2mm. Both groups had 800mm of length, 3.5 mm of wall thickness and tabs laminated with 200 mm length. It was applied a monotonic load with a rate of 6.35 mm/minute. Three strain gages were positioned circumferentially and other three axially oriented at the specimen middle span.
The high temperature was controlled by thermo pairs and the thermal box was heated up to reach the test temperature. So the tests were carried out up to failure of the specimens. The results showed that the sectional area may affect the strain at higher temperatures above of 50 °C. It was also noted variations between both groups regarding their strength capacity, mainly at the serviceable limit state of loading, which was determined by the first lost of loading followed by any kind of possible damage — matrix cracking, delaminating or fiber fracture. It could be noted that for high pressure and severe conditions use, the serviceable limit state is the most appropriated level that one should consider when designing glass fiber reinforced polymer to use in pipelines and others offshore structures subjected to internal and external loading pressures.
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