Further study on the scattering of the local fracture stress and allied toughness value

1991 ◽  
Vol 22 (10) ◽  
pp. 2287-2296 ◽  
Author(s):  
J. H. Chen ◽  
G. Z. Wang ◽  
Z. Wang ◽  
L. Zhu ◽  
Y. Y. Gao
Keyword(s):  
Fracture Stress ◽  
Local Fracture ◽  
Local Fracture Stress

On the scattering of the local fracture stress

1990 ◽  
Vol 38 (12) ◽  
pp. 2527-2535 ◽  
Author(s):  
J.H. Chen ◽  
L. Zhu ◽  
H. Ma
Keyword(s):  
Fracture Stress ◽  
Local Fracture ◽  
Local Fracture Stress

scholarly journals Finite element model to simulate crack propagation based on local fracture stress criterion

2016 ◽  
Vol 2 ◽  
pp. 2558-2565 ◽  
Author(s):  
Yo Nishioka ◽  
Kazuki Shibanuma ◽  
Katsuyuki Suzuki ◽  
Fuminori Yanagimoto
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Finite Element Model ◽  
Fracture Stress ◽  
Element Model ◽  
Local Fracture ◽  
Stress Criterion ◽  
Local Fracture Stress

scholarly journals Brittle fracture in structural steels: perspectives at different size-scales

2015 ◽  
Vol 373 (2038) ◽  
pp. 20140126 ◽  
Author(s):  
John Knott
Keyword(s):  
Brittle Fracture ◽  
Fracture Stress ◽  
Structural Integrity ◽  
Materials Testing ◽  
Local Fracture ◽  
Cooperative Movement ◽  
Test Pieces ◽  
Conclusion Section ◽  
Local Fracture Stress ◽  
Size Scales

This paper describes characteristics of transgranular cleavage fracture in structural steel, viewed at different size-scales. Initially, consideration is given to structures and the service duty to which they are exposed at the macroscale , highlighting failure by plastic collapse and failure by brittle fracture. This is followed by sections describing the use of fracture mechanics and materials testing in carrying-out assessments of structural integrity. Attention then focuses on the microscale , explaining how values of the local fracture stress in notched bars or of fracture toughness in pre-cracked test-pieces are related to features of the microstructure: carbide thicknesses in wrought material; the sizes of oxide/silicate inclusions in weld metals. Effects of a microstructure that is ‘heterogeneous’ at the mesoscale are treated briefly, with respect to the extraction of test-pieces from thick sections and to extrapolations of data to low failure probabilities. The values of local fracture stress may be used to infer a local ‘work-of-fracture’ that is found experimentally to be a few times greater than that of two free surfaces. Reasons for this are discussed in the conclusion section on nano -scale events. It is suggested that, ahead of a sharp crack, it is necessary to increase the compliance by a cooperative movement of atoms (involving extra work) to allow the crack-tip bond to displace sufficiently for the energy of attraction between the atoms to reduce to zero.

scholarly journals Increase in the antioxidant content in biscuits by infusions or Prosopis chilensis pod flour

2021 ◽  
Vol 6 (1) ◽  
pp. 243-253
Author(s):  
Paula Andrea Conforti ◽  
Mariela Patrignani
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Capacity ◽  
Fracture Stress ◽  
Fracture Strain ◽  
Gluten Free ◽  
Maize Starch ◽  
Prosopis Chilensis ◽  
Antioxidant Content ◽  
Fat Level ◽  
Increasing Demand

Abstract Nowadays there is an increasing demand for healthy biscuits. The reduction in sugar and fat level, as well as the addition of bioactive compounds, is positively associated with a healthy diet. In the present work, low-fat and low-sugar biscuits were prepared with infusions (mate, coffee, and tea) or with Prosopis chilensis pod flour (PPF). Biscuits were made with maize starch and wheat flour (gluten formulations) or with gluten-free ingredients (gluten-free). The colour, texture, and the antioxidant capacity were evaluated in dough and biscuits. Among the formulations prepared with infusions, the mate dough showed the lowest firmness (1.1 N (gluten)-24.3 N (gluten-free)). However, no significant differences were found in the fracture stress of the final products (P > 0.05). Mate gluten biscuits and PPF gluten-free biscuits showed the highest fracture strain (16.2 and 9.4%, respectively) and the lowest Young’s modulus (7.3 and 13.3 MPa, respectively) in their groups. The highest antioxidant activity was found in biscuits with mate (8.7 µmol FeSO4/g (gluten)-4.3 µmol FeSO4/g (gluten-free)). These values were three times higher than the ones found in the control biscuits (2.9 µmol FeSO4/g (gluten)-3.9 µmol FeSO4/g (gluten-free)). The present results showed that the antioxidant content in biscuits could be successfully increased with infusion addition.

The effect of the indenter elasticity on the Hertzian fracture of brittle materials

1973 ◽  
Vol 334 (1596) ◽  
pp. 95-117 ◽  
Keyword(s):  
Fracture Stress ◽  
Opposite Effect ◽  
Test Material ◽  
Test Surface ◽  
Dynamic Tests ◽  
Frictional Forces ◽  
Consistent Increase ◽  
Static And Dynamic Tests ◽  
Ring Crack ◽  
Ring Cracks

A spherical indenter loaded statically or dynamically into contact with the surface of a brittle material produces a well-defined ring crack. This phenomenon, when interpreted by the Hertz theory of elastic contact, provides a convenient test for the strength of the material. If the elastic modulus of the indenter is different from that of the test material, e. g. a steel indenter in contact with a glass surface, frictional forces are brought into play at the interface which modify the Hertz distribution of contact stress. This effect has been examined both theo­retically and experimentally. An indenter which is more rigid than the test surface is shown to lead to an apparent increase in fracture strength of the material, a less rigid indenter has the opposite effect. Static and dynamic tests of plate glass showed a consistent increase in apparent fracture stress of about 50 % using spherical steel indenters compared with glass indenters. This increase agrees well with the influence of friction upon the Hertzian stress calculated theoretically. The average radius of the ring cracks produced by steel indenters was observed to be greater than that produced by glass indenters, an effect of friction also predicted by the theory. Secondary ring cracks of smaller radius have frequently been observed during unloading of a steel indenter. These were not found when a glass indenter was used and an explanation is suggested in terms of the frictional effect which arises from a difference in elasticity between the indenter and the test surface.

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