The advancement in science and technology has led to luffa sponge (LS) being widely used as a natural material in industrial application because of its polyporous structure and light texture. To enhance the utility of LS fibers as the reinforcement of lightweight composite materials, the current study investigates their water absorption, mechanical properties, anatomical characteristics and thermal performance. Hence, moisture regain and tensile properties of LS fiber bundles were measured in accordance with American Society for Testing and Materials (ASTM) standards while their structural characteristics were investigated via microscopic observation. Scanning electron microscopy (SEM) was used to observe the surface morphology and fractured surface of fiber bundles. The test results show that the special structure where the phloem tissues degenerate to cavities had a significant influence on the mechanical properties of LS fiber bundles. Additionally, the transverse sectional area occupied by fibers in a fiber bundle (SF), wall thickness, ratio of wall to lumen of fiber cell, and crystallinity of cellulose had substantial impact on the mechanical properties of LS fiber bundles. Furthermore, the density of fiber bundles of LS ranged within 385.46–468.70 kg/m3, significantly less than that of jute (1360.40 kg/m3) and Arenga engleri (950.20 kg/m3). However, LS fiber bundles demonstrated superior specific modulus than Arenga engleri.

The luffa sponge shows excellent cushion properties. This paper presents a bio-inspired structure of the luffa sponge. The geometry of the bionic structure was built based on the fractal theory by Python programming language and prepared by a 3D printer. Then a series of quasi-static compression tests and finite element analysis were carried out to determine the cushion properties. An optimization design was adopted to determine the best design parameter. The results showed that the influence of length (𝑎) on specific energy absorption was more important than the degree (𝜃). The best parameter was found to be length less than 4 mm and angle around 11 degrees. The bionic structure of luffa sponge may show a novel perspective on natural cellular material. The findings demonstrate the great potential for designing hierarchical cellular structures and broad application prospects in the field of cushioning and energy absorption.

The quest for lightweight materials with exceptional energy absorption capabilities has intensified in recent years, driven by the need to engineer robust structures for critical applications such as aerospace, transportation, and nuclear reactor containment. This paper presents a comprehensive study on the design and evaluation of bio-inspired composite quasi-scale specimens under quasi-static loading, with the aim of maximizing energy absorption efficiency. Drawing inspiration from the unique dermal armor of the pangolin, a distinctive mammalian species, we explore the use of sustainable plant fibers, including luffa and linen, as alternatives to traditional glass fibers. The Taguchi method, a robust statistical approach, is employed to systematically investigate the influence of various parameters on the Total Absorbed Energy (TAE) and Specific Absorbed Energy (SAE). A total of five parameters—fiber type, radius of curvature, number of composite plies, and the dimensions of the trapezoidal scales (Y1 and Y2)—are assessed for their impact on energy absorption. The experimental setup involves fabricating composite specimens using unsaturated isophthalic polyester resin as the matrix, and subjecting them to quasi-static lateral compressive loading. The energy absorption characteristics are analyzed by examining the force-displacement data, with the TAE inferred from the area beneath the curve and the SAE calculated by dividing TAE by the specimen's mass. The results indicate that luffa fibers exhibit superior TAE compared to linen and glass fibers, while linen fibers demonstrate higher SAE. The Taguchi method facilitates the identification of optimal parameter levels for maximizing energy absorption, with the predicted optimal specimen exhibiting a TAE of 11.2431 J and an SAE of 2.3677 J/g, closely matching experimental verification with errors of 5.76% and 3.94%, respectively. Theoretical analysis, incorporating the Rigid Perfectly Plastic (RPP) and Hollomon material models, elucidates the mechanisms underlying energy dissipation, including curvature flattening and plastic hinge formation. This framework provides a robust basis for predicting the energy absorption behavior of bio-inspired composite structures, offering insights into the design of advanced materials with enhanced performance characteristics. The study underscores the potential of bio-inspired designs in addressing contemporary engineering challenges, highlighting the synergy between natural forms and advanced materials science in the pursuit of sustainable and high-performance structural solutions.