Influence of end friction confinement on dynamic mechanical properties and damage evolution of concrete by coupled DEM-FDM method

• Published in: Engineering fracture mechanics Vol. 281; p. 109150
• Main Authors: Zhou, Xiang, Xie, Youjun, Long, Guangcheng, Zeng, Xiaohui, Li, Jiangteng, Li, Ning, Wang, Fan, Abdullahi Umar, Hussaini
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 28.03.2023
• Subjects: Coupling DEM-FDM; Damage evolution; Dynamic mechanical response; Interface friction; SHPB; SHPB; Dynamic mechanical response; Damage evolution; Interface friction; Coupling DEM-FDM
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2023.109150

•Crushable aggregates with the real shape are generated by using “ball-clump-cluster” method.•A SHPB simulation test system is proposed by the coupled DEM-FDM method.•The effect of end friction constraint on dynamic compressive behavior of concrete is studied.•The effect of end friction constraint on the distribution of microcracks is quantitatively analyzed. This paper presents a quantitative evaluation of the effect of end friction on the dynamic mechanical response and damage evolution of concrete based on the coupled Discrete Element Method (DEM) - Finite Difference Method (FDM) method. Considering the heterogeneity of concrete, a three-phase meso-scale model of concrete (mortar, aggregate and interfacial transition zone) is constructed by DEM, and the crushability, real geometry and random distribution of aggregates are considered by combining 3D scanning techniques and the “ball-clump-cluster” method. Meanwhile, the split Hopkinson pressure bar (SHPB) device is constructed by FDM, and the interface deformation coordination between the concrete sample and metal rods is realized by coupling algorithm. On this basis, the quantitative effects of end friction on the stress–strain response, dynamic increase factor (DIF), damage distribution and failure mode of concrete are investigated. The results indicate that the dynamic compressive strength increases significantly when the interfacial friction coefficient μi increases from 0 to 0.1, and the interfacial friction enhancement effect weakens significantly when >0 μi.1. With the increase of strain rate, the friction contribution coefficient tends to decrease. The end friction has a significant effect on the distribution of microcracks in the axial direction. The end friction confinement changes the local stress state and damage distribution of concrete, which is beneficial to improve the compressive strength of concrete.