## 1 Introduction
[16] conducted impact response tests on banana, jute, and hybrid epoxy composites. It was mentioned that the hybrid composite offers an outstanding performance when compared to the individual natural fiber composites. Moreover, [PERSON] et al. [17] functionalized the hybrid nanocomposite made up of the nanoclay-reinforcement of either banana fiber, E-glass, or epoxy resin. The results showed that reinforcement using nanoclay inclusions was able to enhance the impact properties. Energy absorption and compression residual strength capabilities are the main variables being analyzed in the impact testing. There have been several studies conducted on the low-velocity impact response and residual strength of composite structures. [PERSON] et al. [18] studied the flexural strength after impact (FAI) of jute-reinforced unsaturated polyester composites. It was found that the FAI significantly decreased with the increase in test temperature and the damage assessment of the composites revealed delamination as the major failure mode. [PERSON] et al. [19] studied the post-impact behaviors of kenaf/glass hybrid composites with different weight proportions following a low-velocity impact test. The compression after impact (CAI) test demonstrated that the compression damage decreased as the impact energy increased. It was further discovered that the kenaf/glass hybrid composite with a 25% kenaf fiber weight ratio gave results that are comparable to those of a glass laminate composite. [PERSON] et al. [20] examined the effect of nanofiller in a bamboo/epoxy composite to enhance the CAI properties. The addition of carbon nanotubes (CNTs) into the composite improved the compression post-impact response properties. The compressive residual strength test was also carried out on flax/polylactic acid (PLA) laminates [21]. The absorbed energy and normalized residual strength were analyzed and the main failure mode in a composite laminate was identified as being fiber failure. Numerous studies have explored the post-impact behavior of glass/epoxy composites, Kevlar/epoxy composites, and other synthetic types of composites. However, only limited findings on the CAI behavior of optimized banana fiber reinforced epoxy composites have been reported. In order to improve the mechanical behavior of the natural fiber composites, many researchers have implemented a well-developed statistical approach including the Taguchi method and the response surface method (RSM). The optimal parameters, such as temperature, molding time, and volume fraction of kenaf-reinforced polyethylene composite, were determined using the Box-Behnken response surface method for ballistic protection, as reported by [PERSON] et al. [22]. Moreover, [PERSON] and [PERSON] [23] evaluated the effect of the fiber load, fiber length, and compatibilizer content on the tensile strength and modulus using the Box-Behnken design. The results showed that the R\({}^{2}\) values and normal probability plots were in good agreement. Furthermore, [PERSON] et al. [24] investigated the mode I fracture toughness of optimized alkali-treated bamboo using the Box-Behnken method. It was suggested that this statistical analysis approach is highly suitable for optimizing the parameters for alkaline-treated bamboo fibers. In previous work, the Box-Behnken method was used to determine the optimal parameters, including fiber length, fiber loading, and chemical treatment concentration, for a banana/epoxy composite [25]. However, there is a need to explore the behavior of this optimal fiber for sandwich structures to fill the knowledge gaps in this particular field of study. In this research, the optimized banana-fiber-reinforced epoxy composites were laminated with carbon/Kevlar will woven skins to form banana epoxy sandwich structures. This current study focused on the low-velocity impact and compression after impact (CAI) response of these structures. The optimal behavior of banana fiber sandwich panels was compared to that of the synthetic fibers including Kevlar, carbon, and glass fibers.