Internally Stressed Polymeric Composite/Metal Cylinders: Manufacturing, Testing and Quality Verifying by Simplified Procedure

 

Jovan Radulović

Nikša Žegarac

 

In this paper the details about manufacturing of multilayer cylinders consisting of metal liner (obtained by standard machining procedures) and polymeric composite material (produced by filament winding technology) are presented. For multilayer cylinders manufacturing three types of steel liner (еach liner type has three different wall thicknesses) are used. Glass fibers impregnated with polyester resin were wound at the outer surface of the mentioned nine liners and so the manufactured multilayer tubes were exposed to the action of internal hydraulic pressure with measurement of deformations in radial direction.

Two groups of the results, obtained during hydraulic testing of multilayer cylinders, were presented: one group represents elastic characteristics, i.e. the properties of the examined tubes at the elastic limit, and another group represents the final properties, i.e. the characteristics of the tested tubes at the moment of burst.

Calculation of the pressure at the elastic limit, by a simplified procedure, was done. By comparing the value of experimentally tested pressure at the elastic limit and the value of calculated pressure at the elastic limit, it was concluded that there is a good agremeent between these two data. Values of experimentally tested radial deformations at the elastic limit of external surface of multilayer tubes and values of this parameter obtained by calculation of simplified model, are, also, meaningfully approximate.

Based on the experimental data, an influence of a pathway from the lower outside liner diameter to higher outside liner diameter was established, and, also, an influence of liner wall thickness on characteristics of multilayer tubes, which were exposed to the action of internal hydraulic pressure.

Based on the introduced parameter hydraulic burst pressure/mass ratio, it was concluded that a higher presence of polymer composite material has positive influence on hydraulic burst pressure (increasing) and mass (decreasing) of the mentioned multilayer tubes.

 

Key words: polymeric materials, composite materials, cylinder, tube, multilayer element, glass fiber, polyester resin, filament winding, hydraulic pressure, elastic characteristics, elastic limit