A Numerical Approach to Separate the Modes of Fracture in Interface Crack Propagation

2005 ◽  
Vol 39 (3) ◽  
pp. 247-264 ◽  
Author(s):  
Mary J. Mathews ◽  
Stephen R. Swanson
Keyword(s):  
Crack Propagation ◽  
Interface Crack ◽  
Numerical Approach

Fracture Toughness of Northeast China Larch

2012 ◽  
Vol 517 ◽  
pp. 661-668 ◽  
Author(s):  
L.P. Qiu ◽  
En Chun Zhu ◽  
Hua Zhang Zhou ◽  
L.Y. Liu
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Stress Intensity ◽  
Crack Propagation ◽  
Material Properties ◽  
Northeast China ◽  
Numerical Approach ◽  
Mode I ◽  
Mode Ii ◽  
Full Size

Wood, as a green and environment-friendly building material, is widely used in building engineering. Naturally grown, wood has various defects like knots, cracks and inclined grain. Fracture Mechanics is thus an efficient tool to investigate the mechanical behavior of wood and wood-based composite products. According to Linear-elastic Fracture Mechanics (LEFM), fracture toughness can be introduced to measure the resistance to crack propagation. Crack was assumed to occur when the stress intensity factorKreached a critical valueKC.Fracture in wood usually involves not only the Mode I type (open) fracture, but also the Mode II type (shear) fracture. For getting a better understanding of the crack growth phenomenon of Northeast China Larch, it is, therefore, essential to assess theKICandKIIC, which are the critical stress intensity factors for Mode I and Mode II type fracture, respectively. In the current study,KICandKIIC, of Northeast China Larch were determined through tests with compact tension specimens and tests with compact symmetric shear specimens, respectively. In addition, the material properties tests were also performed. All of the specimens were cut from the same batch of Glulam beams. Based on the obtained data from experiments, LEFM was employed to explain the fracture failure in the form of crack propagation. Using Extended Finite Element Method (XFEM), simulation of the crack propagation in Mode I and Mode II was performed incorporating ABAQUS. The crack propagation and the load-displacement curves of numerical simulation were in good agreement with experiments, which validated that the proposed numerical approach is suitable for analysis of crack growth in the specimens. As part of a larger program to investigate the fracture behavior of Glulam beams made of Northeast China Larch, this study provides the material properties and validation of the numerical simulation approach. A series of experiments of full-size curved Glulam beams subject to bending and the corresponding simulations extending the numerical approach of this study to the cases of full-size wood composite members are under development.

Fracture toughness of ABS additively manufactured by FDM process

2021 ◽  
Vol 109 (2) ◽  
pp. 49-58
Author(s):  
O. Aourik ◽  
M. Othmani ◽  
B. Saadouki, ◽  
Kh. Abouzaid ◽  
A. Chouaf
Keyword(s):  
Stress Distribution ◽  
Crack Propagation ◽  
Damage Mechanism ◽  
Numerical Approach ◽  
Critical Stress Intensity Factor ◽  
Crack Propagation Resistance ◽  
Functional Part ◽  
Raster Angle ◽  
Cracking Mechanisms ◽  
Exhaustive Study

Purpose: The purpose on this article is to study the failure of FDM printed ABS by exhibiting an exhaustive crack growth analysis mainly based on raster angle parameter. Design/methodology/approach: Two approaches have been developed in this study; On one hand, mechanical experiments were carried out to determine the critical stress intensity factor KIC. On the other hand, numerical analysis was used to predict the paths within the part as well as the crack propagation. Findings: This work has clearly shown the effect of raster angle on the damage mechanism of the ABS printed by FDM. Indeed, for the combination 1 (0°/90°), the structure presents an important stiffness and a high degree of stress distribution symmetry with respect to the notch. Moreover, the crack propagation is regular and straight, and the damage surfaces are on the same plane. However, for the combination 2 (-45°/45°), the structure is less resistant with an asymmetrical stress distribution according to two different planes. Research limitations/implications: In order to present an exhaustive study, we focused on the effect of two raster angles (including 0°/90°, -45°/45°) on the ABS crack propagation, additively manufactured. This study is still in progress for other raster angles, and will be developed from a design of experiments (DoE) design that incorporates all relevant factors. To highlight more the cracking mechanisms, microscopic observations will be developed in more depth. Practical implications: Our analysis can be used as a decision aid in the design of FDM parts. Indeed, we can choose the raster angle that would ensure the desired crack propagation resistance for a functional part. Originality/value: In this article, we have analyzed the mechanism of damage and crack propagation. This topic represents a new orientation for many research papers. For our study, we accompanied our experimental approach with an original numerical approach. In this numerical approach, we were able to mesh distinctly raster by raster for all layers.

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