It is widely known that the availability of lightweight structures with excellent energy absorption capacity is essential for numerous engineering applications. Inspired by many biological structures in nature, bio-inspired structures have been proved to exhibit a significant improvement over conventional structures in energy absorption capacity. Therefore, use of the biomimetic approach for designing novel lightweight structures with excellent energy absorption capacity has been increasing in engineering fields in recent years. This paper provides a comprehensive overview of recent advances in the development of bio-inspired structures for energy absorption applications. In particular, we describe the unique features and remarkable mechanical properties of biological structures such as plants and animals, which can be mimicked to design efficient energy absorbers. Next, we review and discuss the structural designs as well as the energy absorption characteristics of current bio-inspired structures with different configurations and structures, including multi-cell tubes, frusta, sandwich panels, composite plates, honeycombs, foams, building structures and lattices. These materials have been used for bio-inspired structures, including but not limited to metals, polymers, fibre-reinforced composites, concrete and glass. We also discussed the manufacturing techniques of bio-inspired structures based on conventional methods, and adaptive manufacturing (3D printing). Finally, contemporary challenges and future directions for bio-inspired structures are presented. This synopsis provides a useful platform for researchers and engineers to create novel designs of bio-inspired structures for energy absorption applications.

A review of recent research on bio-inspired structures and materials for energy absorption applications

Impact resistance and damage tolerance of fiber reinforced composites: A review

Impact resistance and damage tolerance are of great significance in the design of composite structures. This study investigated the damage and failure mechanism of thin composite laminates under low-velocity impact and compression-after-impact (CAI) loading conditions. Four levels of impact energy were included in the test matrix. Delamination induced by low-velocity impact was captured using ultrasonic C-scan, and a three-dimensional (3D) digital image correlation (DIC) system was employed to measure full-field displacement during the CAI tests. Infrared thermography was also used to online monitor the thermal field variation of the test specimen during the impact and CAI process. The cross sections of typical tested specimens were inspected using an optical microscope and a scanning electron microscope (SEM). A 3D damage model that considers both interlaminar and intralaminar damage was proposed to study the complex damage and failure mechanism. Excellent correlation was obtained between the experimental results and the numerical results. The experimental results obtained from various tests and the results from the numerical simulation were combined to provide a new and deep insight of damage evolution and failure mechanisms under low-velocity impact and CAI loading conditions.

Damage and failure mechanism of thin composite laminates under low-velocity impact and compression-after-impact loading conditions

https://hal.archives-ouvertes.fr/hal-01997671/document

Assessment of failure criteria and damage evolution methods for composite laminates under low-velocity impact

Review and benchmark study on the analysis of low-velocity impact on composite laminates

Modelling damage growth in composites subjected to impact and compression after impact

On the relationship between failure mechanism and compression after impact (CAI) strength in composites

In this study, the underlying mechanism leading to improved impact resistance and energy absorption in bio-inspired composite is investigated through numerical modelling. The bio-inspired composite is inspired from the endocuticle of stomatopods, which is composed of mineralized helicoidal arrangement of fiber layers capable of withstanding high velocity impact. It is shown that the helicoidal architecture gives rise to a unique through-thickness spiralling damage which is in contrast to the damage pattern typically seen in conventional laminates. As a result of the combined effect of the deformation and failure mechanism, the helicoidal laminate can absorb more energy before complete penetration leading to higher ballistic limits. For a 37-ply composite laminate, the ballistic limit of the helicoidal arrangement (151 m/s) is found to be about 8 and 15 percent higher as compared to cross-ply (140 m/s) and quasi-isotropic laminates (130 m/s) respectively. These findings have implications in the design of armours, aerospace and automotive structures.

On the improved ballistic performance of bio-inspired composites

To achieve sustainability in the composite industry, natural fibers must be able to replace synthetic fibers .In this work the tensile properties of sisal fibers were determined. The relationships between tensile strength, young modulus, failure to strain and gage length was studied. Also variation in tensile strength was quantified using statistical analysis. The relationship between Weibull statistics and gage length were also investigated. The strength of the sisal fiber obtained in this work was between 255-377 MPA and decreased with an increase in gage length. The Weibull modulus obtained was similar for all gage lengths and was around 2.5.

Tensile and Statistical Analysis of Sisal Fibers for Natural Fiber Composite Manufacture

Composites subjected to low-velocity impact are prone to abrupt failure during post-impact compression. Impact reduces the compressive residual strength of composites significantly. In many cases, compression after impact (CAI) strength is the critical factor in design. This paper presents an integrated finite element model that aims to predict CAI strength without simplifying or idealizing the damage due to the impact event. Composite laminates impacted at energy levels of 1.6 J, 6.5 J and 17 J are subjected to compression to failure. The CAI strength values as well as delamination and damage patterns correlate well with experiments taken from literature. It was found that failure during post-impact compression is governed by local buckling, which triggers damage growth. An increase in mode Ð†Ð† fracture toughness can essentially reduce delamination size induced during impact, consequently improving residual strength by delaying the onset of buckling (and therefore damage growth) during compression.

M.R. Abir

Papers

Modelling damage growth in composites subjected to impact and compression after impact

On the relationship between failure mechanism and compression after impact (CAI) strength in composites

On the improved ballistic performance of bio-inspired composites

Tensile and Statistical Analysis of Sisal Fibers for Natural Fiber Composite Manufacture

Modelling Failure Mechanisms in Composites Subjected to Impact and Post-impact compression