On the structure and mechanical properties of beetle shells

Hepburn, H. R.; Ball, A.

doi:10.1007/bf00561216

Cited by 90 publications

(66 citation statements)

References 8 publications

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“…The curve demonstrates that both wet and dry whole crab shell exhibits a unique discontinuity in the region of low strain This same discontinuity has been observed for whole prawn shells [42]. However, the bulk tensile stressstrain behavior of isolated crab chitin, prawn chitin [42], regenerated chitin [42], beetle chitin [43]; [2]Hepburn & Ball, 1973) as well as from various insect solid cuticles [2,3,4] is completely free even of any suggestion of such a discontinuity. As in the case of whole prawn shell [24] the occurrence of this discontinuity is associated with the tensile failure of the inorganic salt phase of the skeletons.…”

Section: ііі Results and Discussionsupporting

confidence: 55%

“…Failure of both wet and dry whole crab shell occurs sharply at the ultimate breaking stress and there is no detectable plastic deformation of these materials.. The tensile failure of crab shell differs substantially from the fracture behaviour of prawn shells in which there is a clear delamination of the exocuticle from the endocuticle as well as endocuticular sub-delamination [5] and insect cuticles [2,3,4]. Since there is a sharp increase in the elastic moduli of crab shell on drying, as in other arthropod shells, it is concluded that under normal functional use during life, cuticular water considerably reduces the en-brittling effects of the inorganic salt phase.…”

Section: ііі Results and Discussionmentioning

confidence: 99%

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Investigation of mechanical properties of crab shell: a review

2016

IJLTET

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І. INTRODUCTIONCrab Shell is the second most common natural composite material in the world, and one of the most versatile. Very few mechanical studies have been made on the hard shells (solid cuticle) characteristic of the arthropod integument and it is therefore not yet possible to provide a general model for the mechanical behavior of the exoskeletons of this phylum. Arthropods are the largest animal phylum. They include the trilobites, chelicerates, myriapods, hexapods, and crustaceans. All arthropods are covered by an exoskeleton, which is periodically shed as the animal grows. The exoskeleton of arthropods consists mainly of chitin. In the case of crustaceans, there is a high degree of mineralization, typically calcium carbonate, which gives mechanical rigidity. The various studies carried out on insect solid cuticle[1-4] and prawn shells [5] indicate a number of similarities in the mechanical behaviour of insect and prawn solid cuticle as well as differences apparently due to the fact that the former are two-phase composite materials consisting of chitin fibres in a protein matrix while the latter include another phase, namely inorganic alts, resulting in a three-phase material. In the present review, the mechanical behavior of the solid cuticle of the crab, Scylla serrata, was investigated in order to determine their fracture behavior, microhardness properties and general mechanical behavior as composite materials. This crustacean 1 Department of Mechanical Engineering Government Polytechnic College, Sanawad, M P, India 2 Department of Mechanical Engineering Oriental University Indore, M P, IndiaAbstract-The present review describes the development of investigations of mechanical properties of crab shell. The mechanical behavior of crab shell was investigated. There was low strain discontinuity in their bulk tensile stress-strain curves. The crab cuticle fails in an entirely brittle manner. The cutile of the crab is a composite material, the properties of which are closely analogous to those of pre-stressed concrete. The mechanical properties of the exoskeleton of the sheep crab (Loxorhynchus grandis) were investigated earlier.It was found that the crab exoskeleton is a natural composite consisting of highly mineralized chitin-protein fibers arranged in a twisted plywood pattern. It was observed that there is a high density of pore canal tubules in the direction normal to the surface. Tensile tests were carried out on wet and dry specimens in longitudinal as well as normal directions. Samples tested in the longitudinal direction showed a convex shape and no evidence of permanent deformation prior to failure, whereas samples tested in the normal orientation exhibited a concave shape. The results show that the composite is anisotropic in mechanical properties. Micro indentation was performed to measure the hardness through the thickness. It was found that the outer layer is two times harder than the inner layer.

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Section: ііі Results and Discussionsupporting

confidence: 55%

Section: ііі Results and Discussionmentioning

confidence: 99%

Investigation of mechanical properties of crab shell: a review

2016

IJLTET

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“…Figure 8 illustrates examples of these structural color regimes. Helicoidal Bouligand structures also provide strength to beetle shells and other shell structures (Hepburn and Ball 1973). …”

Section: Photonic Structures and Related Functional Systemsmentioning

confidence: 98%

Biomimetics and Biologically Inspired Materials

Murr¹

2015

Handbook of Materials Structures, Properties, Processing and Performance

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“…10b). Interestingly, a similar failure mode could be observed in some biological composites, such as beetle shells, timber or bones [17].…”

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confidence: 88%

Polypropylene composite materials oriented by solid-state drawing: low-temperature impact behaviour

1993

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Isotactic polypropylene samples, both neat and containing short glass fibres, with two different interfacial adhesions, were oriented by solid state drawing with typical neck propagation. A microscopic examination showed that the glass fibres turned to the orientation direction rather suddenly in the narrow region at the neck shoulder. Such extensive movement of fibres up to 1 mm long indicates high mobility of the polypropylene matrix in this region. Thus, these results seem to support the hypothesis of stress-induced melting of semicrystalline polymers in the propagating neck. The resulting oriented materials showed high resistance to crack propagation at cryogenic temperatures. Inspection of the crack surfaces after impact testing revealed that macroscopic failure was accompanied by multiple fractures and splitting of the specimens along the orientation direction. Such a mechanism effectively blunts the crack tip and dissipates mechanical energy even at very low temperatures.

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On the structure and mechanical properties of beetle shells

Cited by 90 publications

References 8 publications

Investigation of mechanical properties of crab shell: a review

Investigation of mechanical properties of crab shell: a review

Biomimetics and Biologically Inspired Materials

Polypropylene composite materials oriented by solid-state drawing: low-temperature impact behaviour

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