Analysis of local stress/strain fields in an HPDC AM60 plate containing pores with various characteristics. (September 2021)

• Record Type: Journal Article
• Authors: Zhang, Yongfa; Zheng, Jiang; Shen, Fuhui; Han, Weijian; Münstermann, Sebastian; Shou, Haoge; Liu, Qing
• Is Part Of: Engineering failure analysis. Volume 127(2021)
• Publication Date: 2021-09
• Subjects: HPDC -- X-ray tomography -- Finite element analysis -- Pore characteristic; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2021.105503
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: The porosity distribution inside a porous AM60 sample is investigated via XRT. The DIC strain mapping was used to verify the reliability of the FE result which contains 6813 pores with various characteristics. The local stress/strain in the vicinity of large pores evolves progressively along with deformation. The harmfulness of individual pores located in defect bands of HPDC AM60 alloy is firstly evaluated through finite element analysis. Abstract: Casting pores are regarded as the main factor causing stress/strain concentrations, facilitating the initiation of microcracks and shortening the plasticity of a cast component. The influence of pore characteristics (i.e., size, morphology, and position) on local stress concentration in a High Pressure Die Cast (HPDC) AM60 sample is studied utilizing X-ray tomography (XRT) and image-based finite element (FE) techniques. Heterogeneous porosity distribution is identified in terms of volume fraction and projected area ratio per segment. Statistically results demonstrate that small pores (volume < 0.01 mm 3 ) have higher number frequency and sphericity. In contrast, large pores (volume > 0.01 mm 3 ) account for a very low number frequency (0.3%), and complex shape. The present study addresses the local stress/strain behavior in a cast-pore containing HPDC AM60 sample during tensile loading investigated using 3D image-based models which consider the actual size, morphology, and spatial distribution of pores based on XRT images and consider the actual material properties of the AM60 alloy. Simulation results show that the local stress/strain around a pore evolves progressively with deformation. The strain at a certain pore location may be amplified or reduced in the presence of other pores, depending on the specific location of the concerning pores. Also, the ratio between the projected area of a pore and its shortest distance to the free surface (PA/SD) could give a good indication of the max local stress concentration around the pore surface. The weakening of K t pl values of pores found in defect bands are principally due to the pore orientation concerning the load direction. These findings may be extended to provide additional insight into the damage mechanisms in material containing casting pores and to enhance understanding of the ductility variation in terms of local deformation fields around pores and their interactions.