The load–displacement response of Banana and Pineapple fibre under quasi-static nanoindentation test through Load control [LC] and Displacement control [DC] modes

The nanoindentation experimentation was performed using Hysitron TI 950 Triboindenter, equipped with three-sided pyramid Berkovich indenter having a tip radius of less than 300 nm. The response curve of the quasi-static nanoindentation test for both displacement control and load control modes are given. The slop of tangent in the response curve at maximum load during unloading yields the stiffness of material, which was used to calculate reduced modulus (Er) by using Oliver Pharr method. Under the load control mode, the loading was done from zero to a maximum value of 1000 µN at the rate of 10 µN. After a holding time of 10 sec at the maximum load, the unloading was done at the rate of 20 µN. Under the displacement control mode, the maximum depth of indentation was 1 µm with an indenter displacement rate of 10 nm/s on loading. A hold period of 30 sec was provided after reaching the maximum displacement, and the fibre was unloaded at the rate of 20 nm/s. Notable Findings: 1. The indentation moduli were found to be within the range of 2.7 GPa to 4 GPa for banana fibre, and 3 GPa to 4.5 GPa for pineapple fibre. 2. Hardness was found to be in the range of 0.11 to 0.15 GPa for both fibres.

本研究采用Hysitron TI 950 Triboindenter摩擦纳米压痕仪开展纳米压痕试验，该仪器配备尖端半径小于300 nm的三面金字塔形贝科维奇（Berkovich）压头。本文给出了位移控制与载荷控制两种模式下准静态纳米压痕试验的响应曲线。卸载阶段最大载荷处响应曲线的切线斜率可得到材料的刚度，结合奥利弗-法尔（Oliver-Pharr）方法可据此计算约化模量（Er）。载荷控制模式下，加载从0起始，以10 µN的速率升至最大载荷1000 µN；在最大载荷处保载10秒后，以20 µN的速率完成卸载。位移控制模式下，压痕最大深度为1 µm，加载阶段压头位移速率为10 nm/s；达到最大位移后保载30秒，随后以20 nm/s的速率完成卸载。主要研究发现：1. 香蕉纤维的压痕模量介于2.7 GPa至4 GPa之间，菠萝纤维的压痕模量则处于3 GPa至4.5 GPa区间；2. 两种纤维的硬度均处于0.11 GPa至0.15 GPa范围内。