The tensile stiffness and strength

The tensile stiffness and strength were measured according to ASTM tensile test
specifications [21] using coupons with 100 mm gauge length and 25 mm width. Tensile
‘stiffness’ (in N/m) was determined instead of Young’s modulus because of the difficulty
of measuring strain on a fire-damaged laminate. The stiffness was determined from the
gradient of the linear portion of the load/displacement curv