Modeling mechanical responses in a laminated biocomposite
Modeling mechanical responses in a laminated biocomposite
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DOI：
10.1007/s10853-005-0678-8
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发表时间：
2005-04
影响因子：
4.5
通讯作者：
K. Katti;D. Katti;Jing-Ying Tang;S. Pradhan;M. Sarikaya
中科院分区：
文献类型：
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作者：
K. Katti;D. Katti;Jing-Ying Tang;S. Pradhan;M. Sarikaya
利用珍珠层的准六方纳米结构，设计了贝壳的内层珍珠层的三维有限元模型。在这些模型中引入了线性和非线性材料特性，模拟了拉伸试验。通过文献报道的体积测量，获得了珍珠层(文石砖和复合有机相)各组分的材料参数，如弹性模量和硬度。此外，使用原子力显微镜和纳米压痕进行的纳米级实验提供了文石小片和有机相的机械性能。对新模型进行了低应力(2 Mpa)弹性区的线性模拟。我们的模拟表明，要获得实验获得的珍珠层的体相弹性响应，需要一个高模数的有机相(∼，20 Gpa)。我们的纳米压痕实验也证实了模拟结果。在文石的完全弹性行为和有机相的弹塑性模型的假设下进行了进一步的非线性模拟。此外，有机相的屈服应力在40到400兆帕的大范围内变化。将得到的珍珠层屈服应力与实验值进行了比较。我们的模拟再次表明，要获得珍珠层的屈服行为，有机相的异常高的屈服应力是必要的。此外，在三维模型中加入了血小板-血小板矿物接触形式的纳米结构细微差别。定量评价了这些矿物接触对高、低载荷下的线性和非线性响应的影响。我们的模拟首次表明，这些矿物接触的存在对珍珠岩中的线性和非线性响应的影响都很小。事实上，接触是高应力集中的区域，它们在珍珠层开始屈服之前很久就断裂了(∼50 Mpa)。这些结果对模仿珍珠层的可伸缩纳米复合材料的仿生设计具有重要的意义。
Accurate pseudo-hexagonal nanoarchitecture of nacre was used to design three dimensional finite element models of nacre, the inner layer of mollusk shells. Tensile tests were simulated introducing linear and nonlinear material properties in these models. Material parameters of components of nacre (aragonitic bricks and the complex organic phase) such as elastic modulus and hardness were obtained from bulk measurements reported in literature. In addition, nanoscale experiments conducted using atomic force microscopy and nanoindentation provided mechanical properties of aragonite platelets and organic phase. Linear simulations in the elastic regime at low stresses (2 MPa) was conducted on the new models. Our simulations indicate that a high modulus of organic phase (∼ 20 GPa) is necessary to obtain the experimentally obtained bulk phase elastic response of nacre. Our nanoindentation experiments also confirmed the simulations. Further nonlinear simulations were conducted under the assumption of a fully elastic behavior of aragonite and an elastoplastic model for the organic phase. Further the yield stress of the organic phase is varied over a wide range from 40 to 400 MPa. The resulting yield stress of nacre was compared to experimentally obtained value. Again our simulations indicate that an exceptionally high yield stress of the organic phase is necessary to obtain the yield behavior in nacre. Further, nanostructural nuances in the form of platelet-platelet mineral contacts were incorporated in the three dimensional models. The role of these mineral contacts on linear and nonlinear responses under high and low loads was quantitatively evaluated. Our simulations indicate for the first time that presence of these mineral contacts has minimal effect on both linear and nonlinear responses in nacre. As a matter of fact, the contacts are regions of high stress concentration and they break long before yield begins in nacre (∼ 50 MPa). These results have significant ramifications on a biomimetic design of scalable nanocomposites mimicking nacre.