scholarly journals Key Issues in a Benchmarking Exercise for Longitudinal Tensile Failure of Unidirectional Composites

Author(s):  
C. Breite ◽  
A. Melnikov ◽  
F. Mesquita ◽  
S. Lomov ◽  
Y. Swolfs
2012 ◽  
Vol 170-173 ◽  
pp. 1218-1225
Author(s):  
Cong Liu ◽  
Li Wei Chen ◽  
Yan Qiu Leng ◽  
Jian Wei Qiao

Ground fissure disasters are main environmental geological hazards in Xi’an. Therefore, carrying out researches on causes of cracks and mechanisms of hazard-formative, as well as setting economical and effectively countermeasures are major geological disaster puzzles to be solved.According to the key issues existing in the ground fissure researches, we use numerical simulation analysis method to solve them. Numerical simulation analysis shows that, it is reasonable that we use elastic breaking theory to describe its rupture propagation process. This paper introduces smeared crack model and explains the fracture morphology and process of sample which has microcracks inside it. Results show that such sample’s tensile strength is greatly weakened and its tensile failure is brittle fracture. Differential subsidence movement on both sides of the buried ground fissure (fault) not only leads to upwards propagation of existing cracks, whose tendency are opposite to the existing ones, but also leads to the development of nearly vertical crack belt, which is located on the uplift block and develop from top to down. Because of width of buried ground fissures’ affected zone depends on many factors, there are still lots of work to be done on the division of buried ground fissure’s deformation zone.


2021 ◽  
Vol 202 ◽  
pp. 108555
Author(s):  
C. Breite ◽  
A. Melnikov ◽  
A. Turon ◽  
A.B. de Morais ◽  
F. Otero ◽  
...  

Author(s):  
F. I. Grace

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.


Author(s):  
D. J. Wallis ◽  
N. D. Browning

In electron energy loss spectroscopy (EELS), the near-edge region of a core-loss edge contains information on high-order atomic correlations. These correlations give details of the 3-D atomic structure which can be elucidated using multiple-scattering (MS) theory. MS calculations use real space clusters making them ideal for use in low-symmetry systems such as defects and interfaces. When coupled with the atomic spatial resolution capabilities of the scanning transmission electron microscope (STEM), there therefore exists the ability to obtain 3-D structural information from individual atomic scale structures. For ceramic materials where the structure-property relationships are dominated by defects and interfaces, this methodology can provide unique information on key issues such as like-ion repulsion and the presence of vacancies, impurities and structural distortion.An example of the use of MS-theory is shown in fig 1, where an experimental oxygen K-edge from SrTiO3 is compared to full MS-calculations for successive shells (a shell consists of neighboring atoms, so that 1 shell includes only nearest neighbors, 2 shells includes first and second-nearest neighbors, and so on).


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