Testing of the Impregnated Tow

ISO 10618 uses a simplified tab formed by sandwiching the ends of the tow between two pieces of thin card (50 x 20 mm ) using an epoxy resin adhesive. RAE developed a method where a 1 mm diameter sock of glass braid (Peribraid) [19], impregnated with an epoxy adhesive, is pulled over the ends of the cured tow specimen and cured in position. 

Modulus is determined by the attachment of a light weight 50 mm dual gage extensometer, applying a preload (about 5 kgf) and measuring strain up to some 50 kgf, using a crosshead speed of 5 mm/min. Finally the extensometer is removed and the application of the load continued until the sample breaks. 

Note If ((X - outlier)/(T) is greater than the factor, it is classed as an outlier.  

It is useful to mount a steel wire (e.g. a mild steel welding rod) in the end caps to use as a secondary standard (the modulus of steel is 210 GPa). 

To determine whether a dubious result was a flier, the procedure given in Table 17.7 can be adopted. 

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