A numerical and experimental study on the multiple fracture progression of CFRP T-joints under pull-off load. (1st July 2020)

• Record Type: Journal Article
• Authors: Ma, Xueshi; Liu, Hongguang; Bian, Kan; Lu, Jiyun; Yang, Qingda; Xiong, Ke
• Is Part Of: International journal of mechanical sciences. Volume 177(2020)
• Publication Date: 2020-07-01
• Subjects: CFRP T-joint -- Noodle cracking -- Delamination -- Z-pin -- Binary model -- Augmented finite element; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2020.105541
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: Images of multiple fracture progression in composite T-joints were experimentally captured by a high-speed camera. The recent augmentation method achieved a high-fidelity modeling of multiple fracture progression in T-joints, together with cohesive model. It was revealed that noodle cracking induced interface delamination is responsible for the final failure. The augmentation method was coupled with binary model to quantify the improvement in delamination resistance of Z-pinned T-joints. Abstract: This paper reports a combined numerical and experimental study on the multiple fracture evolution in carbon fiber reinforced polymer (CFRP) T-joints under pull-off load. The experimental study successfully captured the sequential fracture initiation and evolution involving a complex interplay among noodle cracking, noodle-skin and skin-stiffener delamination, and their correlation with the load-displacement curves. Numerically, two independent numerical methods, (a) the extend finite element method (X-FEM) available in ABAQUS, and (b) the augmented finite element (A-FEM) method, are used to cross-check their predictive capability in modeling progressive fracture evolution in the T-joints. It is found that, although the nonlinear load-displacement curves predicted by both methods are consistent with experimental data, their predictions on fracture progression responsible for final failure are different. The A-FEM prediction is in good agreement with experimental record while the X-FEM's prediction is inaccurate. Finally, the validated A-FEM model is coupled with the Binary Model to quantify the improvement in fracture resistance using the Z-pin reinforcement technique. The simulation results, which are validated by previously reported experimental data, show that properly arranged Z-pin reinforcement can improve the fracture tolerance and significantly delay the final failure of T-joints. Graphical abstract: Image, graphical abstract