Table 4: Principal stresses obtained from biaxial tension experiments on EP 280 Prepreg, where is the First-Stress Invariant based on the mechanical stresses [9] and is the First-Stress Invariant based on both the mechanical and residual stresses.

Test numberMechanical stresses [9]Residual stresses% difference
(MPa) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)

1137.6532.614.60174.865.074.75−5.32179.363%
295.5850.9233.62180.125.074.75−5.32184.622%
3178.0228.10−55.32150.85.074.75−5.32155.33%
476.5444.6727.80149.015.074.75−5.32153.513%
5105.2637.0331.22173.515.074.75−5.32178.013%
670.0840.5125.35135.945.074.75−5.32140.443%
789.9629.4324.34143.735.074.75−5.32148.233%
886.8049.7731.23167.85.074.75−5.32172.33%
9101.2535.6130.37167.235.074.75−5.32171.733%
10112.0941.3835.04188.515.074.75−5.32193.012%
11138.4743.9231.65214.045.074.75−5.32218.542%
12162.0554.1843.34259.575.074.75−5.32264.072%
13118.4431.9110.68161.035.074.75−5.32165.533%
14149.6850.5741.22241.475.074.75−5.32245.972%
1589.7925.789.90125.475.074.75−5.32129.974%
16104.4144.6910.80159.95.074.75−5.32164.43%
17124.8737.5323.61186.015.074.75−5.32190.512%
1879.5729.4225.48134.475.074.75−5.32138.973%
1996.0236.5131.16163.695.074.75−5.32168.193%
20121.9546.1639.50207.615.074.75−5.32212.112%
21137.8254.9146.36239.095.074.75−5.32243.592%
22107.5355.1840.24202.955.074.75−5.32207.452%
2376.4330.9327.04134.45.074.75−5.32138.93%
24115.9650.5940.71207.265.074.75−5.32211.762%
2598.0839.9434.69172.715.074.75−5.32177.213%
2668.6027.5324.21120.345.074.75−5.32124.844%