Dynamic Mode Ⅱ fracture behavior of rocks under hydrostatic pressure using the short core in compression (SCC) method

This study explores the role of rubber toughening on the dynamic fracture behavior of additively manufactured (AM) high-performance thermosetting polymers formed through digital light processing (DLP). Using DLP to create these polymers allows for rapid, agile manufacturing of prototypes meeting the lightweight and building speed requirements of relevance to military mission applications. This method also provides flexibility in part complexity while maintaining relatively high isotropy compared to traditional AM techniques. Previous work has demonstrated a dependence of these DLP specimens on print layer orientation and loading rate, prompting further investigation into other manufacturing parameters to improve toughness [1]. This study examines the role of rubber toughening on the quasi-static and dynamic fracture behavior of bis-GMA thermosets. Current literature largely reports on quasi-static behavior of DLP specimens, although dynamic conditions are more applicable to many realistic loading scenarios and extreme environments often seen in defense applications. Dynamic experiments leverage a unique long bar striker device that impacts a specimen opposite a pre-crack, sending a stress-wave driven load to initiate a dynamic Mode-I (opening) fracture event. Full-field displacement data ahead of the propagating crack is obtained using ultra high-speed imaging combined with 2D digital image correlation (DIC). An elastodynamic solution following the principles of dynamic fracture mechanics extracts the stress intensity factor (SIF) using a least squares fit at crack initiation and a Newton-Raphson scheme for crack propagation. The rubber toughened thermosets in this study exhibited a rate dependence in fracture toughness with the quasi-static SIF being 1.20 MPa and the dynamic SIF being 0.41 MPa .

Download Full-text

Deformation and fracture behavior of granite by the short core in compression method with 3D digital image correlation

Fatigue & Fracture of Engineering Materials & Structures ◽

10.1111/ffe.13606 ◽

2021 ◽

Author(s):

Diyuan Li ◽

Chenxi Zhang ◽

Quanqi Zhu ◽

Jinyin Ma ◽

Feihong Gao

Keyword(s):

Digital Image Correlation ◽

Digital Image ◽

Fracture Behavior ◽

Image Correlation ◽

Compression Method ◽

3D Digital Image Correlation ◽

Deformation And Fracture ◽

Short Core

Download Full-text

Fracture Toughness and the Effects of Stress State on Fracture of Nickel Aluminides

MRS Proceedings ◽

10.1557/proc-186-341 ◽

1990 ◽

Vol 186 ◽

Cited By ~ 1

Author(s):

John J. Lewandowski ◽

Gary M. Michal ◽

Ivan Locci ◽

Joseph D. Rigney

Keyword(s):

Stress State ◽

Hydrostatic Pressure ◽

Tensile Testing ◽

Fracture Behavior ◽

Room Temperature ◽

In Situ Monitoring ◽

High Toughness ◽

Tension Tests ◽

Effects Of Stress

AbstractThe effects of stress state on the fracture behavior of Ni3Al, Ni3Al + B, and NiAl were determined using either notched, or fatigue-precracked bend bars tested to failure at room temperature, in addition to testing specimens in tension under superposed hydrostatic pressure. Although Ni3AI is observed to fail in a macroscopically brittle intergranular manner in tension tests conducted at room temperature, the fracture toughnesses (i.e. K IC presently obtained on Ni3Al exceeded 20 MPa1m and R-curve behavior was exhibited. In-situ monitoring of the fracture experiments was utilized to aid in interpreting the source(s) of the high toughness in Ni3Al, while SEM fractography was utilized to determine the operative fracture modes. The superposition of hydrostatic pressure during tensile testing of NiAl specimens was observed to produce increased ductility without changing the fracture mode.

Download Full-text