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| 1 | 脆性材料在韧性域内的往复纳米划痕深度预测研究显示文摘提出了一种基于多道次划痕法的划痕深度的预测模型,在此模型中,基本假设为在针尖与材料弹性接触后,在每道次划痕中的划痕深度增量与赫兹接触理论得到的最大剪应力深度成正相关。随后通过建立每道次划痕时针尖与样品接触半径的递推关系,获得每道次划痕深度增量的递推关系,并通过划痕深度增量的总和来建立多次划痕深度的预测模型。考虑到脆性材料在多次划痕过程中会出现力学性能的变化,因此在预测模型中引入了材料弹性模量的修正方程以提高预测模型的精确性。为了验证上述模型的可靠性,本研究在压痕弹性载荷作用下,以磷酸盐激光玻璃为样品,采用球形金刚石针尖进行了多道次往复纳米划痕试验,并实现了对不同次数下的纳米划痕深度的预测。在通过对玻璃样品的弹性模量修正后,发现预测划痕深度和试验深度吻合度高。修正后的弹性模量根据划痕载荷的不同表现为随划痕次数不同的变化趋势,这与玻璃材料在不同载荷下剪切应力诱发的致密化与损伤软化相关。本研究所提出的计算模型理论基础可靠,同时考虑了材料自身力学性能的变化,因此有望推广到其他脆硬材料的纳米划痕变形演变预测中。 | 于洲 余家欣 袁卫锋 赖建平 何洪途 | 2021 | 机械工程学报2021，57，15： | 2 |
| 2 | 易解理氧化镓晶体微尺度力学行为试验研究显示文摘为了探寻单晶氧化镓晶体超精密加工的易切削方向以及临界切削深度,将单晶氧化镓晶体(100)晶面和(010)晶面等角度划分成24等份,对每个方向上用Berkovich金刚石压头进行纳米压痕试验、用Cube金刚石压头进行纳米压痕和划痕试验。试验结果表明,在(100)晶面120°方向上脆塑转变临界切深最大,为623 nm左右,此时脆塑转变临界载荷为29.4 mN;在(010)晶面105°方向上脆塑转变临界切深最大,为686 nm左右,此时脆塑转变临界载荷为20.0 mN。氧化镓晶体存在强烈的各向异性,其中(010)面各向异性较为强烈。对比硬度、弹性模量、断裂韧度和相对脆塑转变临界切深随方向的变化趋势,结合各方向的划痕试验结果可以看出,氧化镓晶体(010)面为易加工晶面,105°方向为易加工方向。 | 徐亚萌 周海 张杰群 任相璞 张春伟 | 2022 | 中国机械工程2022，33，18： | 1 |
| 3 | Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals:characterization by nanoindentation显示文摘Potassium dihydrogen phosphate(KDP)crystals are widely used in laser ignition facilities as optical switching and frequency conversion components.These crystals are soft,brittle,and sensitive to external conditions(e.g.,humidity,temperature,and applied stress).Hence,conventional characterization methods,such as transmission electron microscopy,cannot be used to study the mechanisms of material deformation.Nevertheless,understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process.This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations.The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals,and dislocation pileup leads to brittle fracture during nanoindentation.Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals,and plastic deformation and brittle fracture are related to the material's anisotropy.However,the E l Ning Hou 13b908074@hit.edu.cn Liang-Chi Zhang liangchi.zhang@unsw.edu.au 1 School of Mechatronics Engineering,Harbin Institute of Technology,Harbin 150001,People's Republic of China 2 School of Mechatronics Engineering,Shenyang Aerospace University,Shenyang 110136.People's Republic of China'Laboratory for Precision and Nano Processing Technologies,School of Mechanical and Manufacturing Engineering,The University of New South Wales,Sydney,NSW 2052,Australia effect of loading rate on the KDP crystal deformation is practically negligible.The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components. | Yong Zhang Ning Hou Liang-Chi Zhang Qi Wang | 2020 | Advances in Manufacturing2020，8，4： | 0 |
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