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Stepped repair, scarf patch repair, and patch repair are important in terms of repair techniques. The composite plate repair process starts after damage zone determination either by the unaided eye or nondestructive testing (NDT) techniques. This study investigates design cases for the stepped repairs of damaged fiber-reinforced composite materials. Before preparing steps for repair, the material around the damage zone is removed. In the stepped repair, it needs extra care to ensure that the repair plies overlap each other properly in the cut. Different cases are performed considering different step sizes. 5, 10, and 15 mm step sizes are used. The damages are given to the produced fiber-reinforced composite laminates using the Quasi-static indentation (QSI) method. Using QSI high-velocity impact simulation can be done. To get damage characteristics well-known damage test method is issued. Different span-to-punch diameter ratio (SPR) values were also used to compare different damage sizes. As a result, High ratio strength recovery was obtained using the longer step size. Maximum penetration force was reduced by nearly % 6-7 and maximum stress reduction was obtained by nearly % 8-9 for the 15 mm step size repaired composites. Among the all cases, case-1 has the highest strength recovery and case-5 has the lowest. For SPR 2, The average ultimate force value of specimens repaired with case-1 was maintained at nearly 94%. For SPR 4, repairs carried out using case-1 maintain more than 95% of damage resistance. [ABSTRACT FROM AUTHOR]

In this study, the behavior of composite material produced using basalt, a natural fabric, under ballistic and Charpy impact loads was investigated. The damage resistance of target plates under ballistic loads is an important design parameter in the structures that will be exposed to these loads. Cross‐ply fiber‐reinforced composite plates were produced with different numbers of layers. The composite specimens are produced using the vacuum infusion method, cross‐ply laminated with 3, 6, 9, and 12 layers ([0/90]3, [0/90]6, [0/90]9, and [0/90]12). Carbon/Epoxy specimens were also produced in identical sequences to be used as comparison material. The study aimed to understand the absorbed energy under ballistic loads and the required energy level under the Charpy impact loads of Basalt/Epoxy composite specimens with different thicknesses. Ballistic loads are applied to the specimens using a test set‐up including the sample holder mechanism and a firing system. Charpy impact tests were conducted using a standard test machine. According to the results, for 12‐layer specimens, the residual velocity difference between Basalt/Epoxy and Carbon/Epoxy is approximately 1.5 times. For the Basalt/Epoxy plate, increasing number of layers from 3 to 12 increases the amount of energy absorbed approximately 13 times. Although this increase is approximately 19 times for the Carbon/epoxy plate, when Basalt/Epoxy and Carbon/Epoxy plates are compared, Basalt/Epoxy absorbs more energy for all layer numbers. For the Charpy impact cases, it has been observed that Basalt/Epoxy absorbs approximately 34% more energy for flat wise impact and approximately 24% more energy for edgewise impact. Highlights: The behavior of composite material produced using basalt, a natural fabric.Cross‐ply fiber‐reinforced composite plates.Effect of different number of layers considered.The damage resistance of target plates under ballistic loads.Comparison of basalt and carbon‐reinforced composites. [ABSTRACT FROM AUTHOR]