Role of void shape on shock responses of nanoporous metallic glasses via molecular dynamics simulation. (15th March 2022)

• Record Type: Journal Article
• Authors: Song, Weidong; Yu, Yongji; Guan, Yunlong
• Is Part Of: International journal of mechanical sciences. Volume 218(2022)
• Publication Date: 2022-03-15
• Subjects: Metallic glasses -- Nanoporous -- Mechanical response -- Shock loading -- Molecular dynamics; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2022.107076
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: The effect of void shape on plastic deformation and void collapse mode in nanoporous metallic glasses is investigated. The void shape plays an important role in the spall damage evolution. The spall strength is related to the average degree of the local five-fold symmetry and the true strain rate on the spall plane. Abstract: The void shape significantly affects the mechanical properties of nanoporous metallic glasses (NPMGs) under conventional loading. However, how the shock responses of NPMGs depend on the void shape has been rarely studied. In this work, shock simulations of Cu50 Zr50 NPMGs containing voids with different shapes are performed by molecular dynamics, aiming to investigate the roles of the void shape on plastic deformation, void collapse, and spallation. The results reveal that the void shape has a significant effect on the peak value of the atomic strain curve and the fraction of atoms participating in the plastic deformation. There is a very weak dependence of the void collapse mode on the void shape under the weak shocks, where the voids collapse perpendicularly to the shock direction. As the shock strength increases, the void collapse mechanism gradually transforms into an internal jet, and the void shape plays an important role in the jet formation. During spallation, the initial damages tend to concentrate in the void collapse regions and then coalesce into large damages. The void shape influences the coalescence degree of spall damage. The spall strength is positively correlated with strain rate and local five-fold symmetry, but negatively correlated with temperature on the spall plane. Additionally, the void influences the spall strength due to the different distribution of the above factors after voids collapse in nanoporous samples. Graphical abstract: Image, graphical abstract