Size-effect method for determining fracture energy and process zone size of concrete

1990 ◽  
Vol 23 (6) ◽  
pp. 461-465 ◽  
Author(s):  
S. P. Shah
Keyword(s):  
Size Effect ◽  
Fracture Energy ◽  
Process Zone ◽  
Zone Size ◽  
Effect Method

Effect of the shape of the softening damage law on the predicted tensile fracturing and energy dissipation in textile composites

2021 ◽  
pp. 105678952098684
Author(s):  
Jing Xue ◽  
Kedar Kirane
Keyword(s):  
Size Effect ◽  
Fracture Energy ◽  
Process Zone ◽  
Textile Composites ◽  
Material Point ◽  
Sudden Drop ◽  
Damage Models ◽  
Wide Range ◽  
Damage Law ◽  
Linear Softening

The fracturing behavior of fiber-reinforced composites is often modeled using continuum damage mechanics-based approaches which commonly assume a linear softening damage law, i.e. a linearly decreasing stress with increasing strain. The objective of this paper is to assess the suitability of this assumption for composites and to systematically analyze the effect of the assumed shape of the softening damage law at material point, on the predicted fracturing behavior of the structure. The material considered is an epoxy/carbon-fiber twill woven composite. Numerical evaluations are conducted by predicting the strength size effect and progressive accumulation of damage in a structure and comparing with experimental measurements. Damage models with a wide range of shapes of softening laws are considered. These include linear, bilinear, trilinear, exponential, power law and sigmoidal. The effect of introducing a sudden drop in the damage law is also evaluated. All modeling is conducted via the crack band model (CBM), to ensure the mesh objectivity of results. It is found that despite using the right strength and fracture energy as input at the material point level, not all softening law shapes can accurately predict the strength size effect and post-peak softening. Especially the sudden drop feature leads to severe underprediction of strength. Bilinear softening shows the best combination of simplicity and accuracy, especially if formulated via the R-curve approach. Further insights are obtained by assessing the predicted fracture process zone size and fracture energy via the size effect method. Finally structure level predictions are made by considering plug initiated axial crushing of a cylindrical crushcan. The close ties between the shape of the material softening law and predicted process zone, and structural fracturing are revealed, and shown to be an important consideration in formulating damage models.

scholarly journals Parameter interdependence of dynamic self-similar crack with distance-weakening friction

2020 ◽  
Vol 223 (3) ◽  
pp. 1584-1596
Author(s):  
Shiro Hirano ◽  
Hiromichi Itou
Keyword(s):  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Process Zone ◽  
Slip Rate ◽  
Zone Size ◽  
Rupture Velocity ◽  
Self Similar

SUMMARY In several analytical and numerical studies, the slip rate function and energy release rate for dynamic self-similar crack growth have been investigated, and the results obtained have contributed to a theoretical understanding and estimation of on-fault energetics. However, the relationships among physical parameters, including stress state, process zone size, rupture velocity, peak slip rate and energy release rate, are still unclear. Therefore, the aim of this study is to derive an analytical solution of the slip rate distribution of antiplane self-similar crack growth under distance-weakening friction that mimics slip-weakening friction. To satisfy the condition that the slip rate starts from zero at the rupture front, a trade-off relationship among rupture velocity, process zone size and breakdown stress-to-stress drop ratio is proposed. The peak slip rate, slip-weakening distance and fracture energy obtained using the proposed model provide a possible mechanism for the determination of the rupture velocity and the estimation of the fracture energy of the self-similar crack growth, based on the seismic observables.

Fracture process zone size and true fracture energy of concrete using acoustic emission

2010 ◽  
Vol 24 (4) ◽  
pp. 479-486 ◽  
Author(s):  
S. Muralidhara ◽  
B.K. Raghu Prasad ◽  
Hamid Eskandari ◽  
B.L. Karihaloo
Keyword(s):  
Acoustic Emission ◽  
Fracture Energy ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Zone Size ◽  
True Fracture
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