Abstract
This study quantifies how pressurized water-immersion aging degrades the tribological response of cross-ply E-glass/polyester laminates by coupling dual-mode testing with surface metrology and factorial ANOVA. Eleven-ply [0/90]s plates were aged at 10 bar for 0, 7, 14, and 21 days, gaining 10% mass (72.2 to 79.4 g), then tested under 20 N in ball-on-disc (50-100 mm s(-1); 100-200 m) and reciprocating modes (1-2 Hz; 10-20 m). In ball-on-disc tests, steady-state COF rose from 0.40 to 0.47 (unaged) to 0.49 to 0.52 (14-21 days), and the low-friction run-in largely vanished with aging. Wear scar width and depth increased from 1.38 to 1.90 mm and 75 to 117 µm, respectively. Reciprocating tests showed a non-monotonic trend: moderate aging lowered COF to 0.50, whereas 21 days produced the harshest response (up to 0.78) and the widest/deepest scars (1.15 to 1.95 mm; 40 to 110 µm). ANOVA revealed that, in ball-on-disc tests, the COF was governed by sliding distance (28.70%) and speed (24.64%), with a strong Days × Speed interaction (31.66%); track-depth variance was dominated by distance (42.16%) and aging (32.16%). For the COF under reciprocating tests, aging was the leading main effect (21.21%), with large Days × Frequency (20.36%) and Days × Track (20.03%) interactions. Uniquely, this study isolates the effect of controlled hydrostatic aging (10 bar) and compares two sliding kinematics under identical loads, establishing quantitative thresholds (14 and 21 days) where interfacial debonding and third-body abrasion accelerate.