It is essential to obtain preliminary design data of composite marine vehicles operated in harsh marine environments, such as those with hygrothermal and impact effects. The effects of hygrothermal aging and stacking sequence on the low-velocity impact (LVI) response of carbon fiber epoxy composite plates (CFRP) were investigated experimentally. CFRP plates in six orientations [0°/90°/45°/−45°]s, [90°/45°/−45°/0°]s, [0°/90°/0°/90°]s, [90°/0°/90°/0°]s, [−45°/45°/−45°/45°]s, and [45°/−45°/45°/−45°]s (quasi-isotropic, cross-ply, and angle-ply) were manufactured using a vacuum-assisted resin infusion method. LVI tests were performed by using the Ceast 9350 Fractovis Plus impact machine. Four aging conditions (atmospheric, 2, 4, and 6 weeks aged) were simulated using Ascott CC 1000ip programmable salt spray and cyclic corrosion test chamber cabin. The effect of the ply-stacking sequence plays an important role in the failure of the top or bottom surface of the plate samples and dent depth. When 0-degree fiber is used on the upper and lower surfaces of the plates, the dent depth is lowest, followed by 90, +45, and −45°, respectively. Dent depth and top surface fiber cracking lengths generally decrease as the process begins with initial atmospheric conditions reaching 6 weeks.

Carbon-reinforced epoxy laminated composite (CREC) structures are increasingly utilized in high-speed marine vehicles (HSMVs) due to their high specific strength and stiffness; however, they are frequently subjected to impact loads like slamming and aggressive environmental agents during operation. This study experimentally investigates the Compression After Impact (CAI) behavior of CREC plates with varying lamination sequences under both atmospheric and accelerated aging conditions. The samples were produced using the vacuum-assisted resin infusion method with three specific orientation types: quasi-isotropic, cross-ply, and angle-ply. To simulate the marine environment, specimens were subjected to accelerated aging in a salt fog and cyclic corrosion cabin for periods of 2, 4, and 6 weeks. Before and following the aging process, low-velocity impact tests were conducted at an energy level of 30 J, after which the residual compressive strength was measured by CAI tests. At the end of the aging process, after the sixth week, the performance of plates with different layer configuration characteristics can be summarized as follows: Plates 1 and 2, which are quasi-isotropic, exhibit opposite behavior. Plate 1, with an initial toughness of 23,000 mJ, increases its performance to 27,000 mJ as it ages, while these values are around 27,000 and 17,000 mJ, respectively, for Plate 2. It is thought that the difference in configurations creates this difference, and the presence of the 0° layer under the effect of compression load at the beginning and end of the configuration has a performance-enhancing effect. In Plates 3 and 4, which have a cross-ply configuration, almost the same performance is observed; the performance, which is initially 13,000 mJ, increases to around 23,000 mJ with the effect of aging. Among the options, angle-ply Plates 5 and 6 demonstrate the highest performance with values around 35,000 mJ, along with an undefined aging effect. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed the presence of matrix cracking, fiber breakage, and salt accumulation (Na and Ca compounds) on the aged surfaces. The study concludes that the impact of environmental aging on CRECs is not uniformly negative; while it degrades certain configurations, it can enhance the toughness and energy absorption of brittle, cross-ply structures through matrix plasticization.