Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Viet Nam; Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Viet Nam.
J Mech Behav Biomed Mater. 2019 Aug;96:9-19. doi: 10.1016/j.jmbbm.2019.04.027. Epub 2019 Apr 18.
This paper applied non-linear theory of elasticity (NLTE) to partition indentation-induced deformations into elasticity and plasticity for lithium metasilicate glass ceramic (LMGC), sintered and pressed lithium disilicate glass ceramics (SLDGC and PLDGC). It also used elastic plastic fracture mechanics (EPFM) approach to analytically predict machinability for these materials. Using the Sakai's series elastic and plastic deformation model that applied NLTE, the resistances to plasticity for LMGC, SLDGC and PLDGC were extracted from their respective indentation-extracted plane strain moduli and contact hardness values. Plane strain moduli and resistances to plasticity were used to calculate elasticity and plasticity for these materials. Furthermore, the EPFM approach in the Sakai-Nowak model was applied to deconvolute resistances to machining-induced cracking for these materials. All properties were extracted at 10 mN peak load and 0.1-2 mN/s loading rates to determine the loading-rate influence on these properties. The resistances to plasticity of LMGC and SLDGC were loading rate dependent (ANOVA, p < 0.05) and the resistance to plasticity of PLDGC was loading rate independent (ANOVA, p > 0.05). The strain rate sensitivity model was used to find the intrinsic resistances to plasticity for LMGC and SLDGC. The elastic displacement/deformation components were dominant for LMGC at all loading rates. For SLDGC and PLDGC, the deformation mechanisms were dynamic with the plastic and elastic deformation components dominating at low loading and high loading rates respectively, a phenomenon attributed to indentation energies. The decrease in plastic displacements for all materials with increase in loading rate was due to the strain hardening behaviour. Also, PLDGC revealed the highest absorbed energy followed by SLDGC and LMGC. Finally, PLDGC had the highest resistance to machining-induced cracking followed by SLDGC and LMGC. This study provides a quantitative basis to rank materials in terms of brittleness, ductility and resistance to mechanically-induced cracking.
本文将非线性弹性理论（NLTE）应用于锂硅酸钠玻璃陶瓷（LMGC）、烧结和压制的二硅酸锂玻璃陶瓷（SLDGC 和 PLDGC）的压痕诱导变形，将其分为弹性和塑性。还使用弹塑性断裂力学（EPFM）方法对这些材料的可加工性进行分析预测。利用 Sakai 的系列弹性和塑性变形模型，该模型应用了 NLTE，从各自的压痕提取平面应变模量和接触硬度值中提取了 LMGC、SLDGC 和 PLDGC 的塑性变形阻力。平面应变模量和塑性变形阻力用于计算这些材料的弹性和塑性。此外，还应用了 Sakai-Nowak 模型中的 EPFM 方法来反卷积这些材料的加工诱导开裂阻力。所有性能均在 10 mN 峰值载荷和 0.1-2 mN/s 加载速率下提取，以确定这些性能对加载速率的影响。LMGC 和 SLDGC 的塑性变形阻力与加载速率有关（ANOVA，p<0.05），而 PLDGC 的塑性变形阻力与加载速率无关（ANOVA，p>0.05）。应变率敏感模型用于确定 LMGC 和 SLDGC 的固有塑性变形阻力。对于所有加载速率，LMGC 的弹性位移/变形分量均占主导地位。对于 SLDGC 和 PLDGC，变形机制为动态的，在低加载和高加载速率下分别以塑性和弹性变形分量为主，这种现象归因于压痕能量。随着加载速率的增加，所有材料的塑性位移减小是由于应变硬化行为。此外，PLDGC 显示出最高的吸收能量，其次是 SLDGC 和 LMGC。最后，PLDGC 对机械诱导开裂的阻力最大，其次是 SLDGC 和 LMGC。本研究为根据脆性、延展性和对机械诱导开裂的阻力对材料进行排序提供了定量基础。
