Studies On The Structure,Growth Pattern And Mechanical Properties Of Conch Conus Litteratus

Firstly, the crystal structure phase of Conus litteratus was detail studied with XRD and DSC, while the whole and some local structures were observed by SEM. The phase analysis and thermal analysis experiments found that Conus litteratus is mainly consist of aragonite and organic matter. Under the action of organic matter and moisture, the temperature of the aragonite transform to calcite in the Conus litteratus is far lower than the temperature of pure aragonite transform to calcite. The SEM observation showed the body part of the last whorl of Conus litteratus is made up of three macro layers, while there are only two layers on the lip part; The base is composed of repeating unit, which can be divided into six parts. However, the basic structure of Conus is long rod-shaped aragonite, and the structure can be classified as third order lamellar, second order lamellar and first order lamellar by different scales.Secondly, structures of certain parts of the mature conus were observed by SEM. The results showed that the three crossed lamellar of the shell have the specific growth sequence. In the spiral growth direction, for the body part, the outer layer was deposited firstly, then the middle layer, and the inner layer was on the last; for the base, the outer layer deposited earliest, followed by stuffer region of crescent shape, and then the middle layer, the inner layer, the arc transitional area deposited step by step. The aragonites on the interface of the three crossed lamellar structure nested with each other, realizing zigzag seamless connection. Besides, when new whorl grows on the old whorl, a micro grade transition zone of horizontal alignment will take the lead on the surface.Lastly, based on the SEM observation of the whole structure of Conus litteratus, three-point bending tests and compression tests were carried out on the different orientation of the rectangle samples. The results showed the mechanical properties of the cone shells were obvious anisotropy. The arrangement of the middle layer has great influence on the strength of bending and compression, while the outer and inner layers are very thin but play a protective role for the middle layer. The lip parts of the shell can be easily broken by external force, and the scars on the surface of the mature cone shells are records of the repair process. The bending strength of samples that removed organic matters is 1/5 of fresh samples. Therefore the organic matters have a great significance on maintaining the whole strength of the shells.