Recent Applications and Potentialities - Biaxial Testing for Fabrics and Foils - page 119

Fig. 5.1 Imposed strain-paths (a, c) and histories (b, d): in test of type A warp direction is
stretched first, in tests of type B fill direction is stretched first (Beccarelli et al. 2013 )

5.1.2 The Testing Setup

The tests have been carried out with the biaxial testing machine described in
Sect. 3.4.2.4 based on a rigid square frame 1,852 mm × 1,852 mm with batteries
of independent servomotors, three per side, able to develop a maximum axial
force of 25 kN and equipped with speci

c clamps for architectural fabrics. For
each actuator the force is measured through a force transducer and the position
known thanks to the control of the brushless motor. Elongations (and hence
strains) in the zone of interest are measured through two linear potentiometers
used as contact extensometers. The samples have a cruciform shape with a central
square of 300 mm 300 mm, each arm is divided into three strips 100 mm wide

and 200 mm long, with additional 100 mm of material used for the clamping
system. They have been extracted from the same batch of material, a PVC coated
polyester fabric; Ferrari Precontraint ® 1002 white/blue 538 opaque characterised
by an ultimate tensile strength of 420/400 daN/5 cm in warp/

×

ll direction.