An experimental study of dynamic tensile failure of rocks subjected to hydrostatic confinement

2016 ◽  
pp. 197-202
Author(s):  
B Wu ◽  
K Xia
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Taoli Xiao ◽  
Mei Huang ◽  
Min Gao

An experimental study of a rock-like material containing a preexisting fissure subjected to loading and unloading triaxial compression is carried out, and the results show that the mechanical characteristics of the rock-like specimen depend heavily on the loading paths and the inclination of the fissure. The triaxial loading experiment results show that the failure strength linearly increases, while the residual strength linearly decreases with increasing inclination. Furthermore, specimens subjected to triaxial compression show an “X”-type shear failure mode. The triaxial unloading compression experimental results show that specimens with different inclination angles have various failure modes. Specimens with gentle inclinations show a tensile-shear mix failure mode, specimens with middle inclinations show a shear-sliding failure mode, and specimens with steep inclinations show a tensile failure mode. These findings can be used to forecast excavation-induced instabilities in deep underground engineering rock structures.


2006 ◽  
Vol 33 (4) ◽  
pp. 373-383 ◽  
Author(s):  
S Willibald ◽  
J A Packer ◽  
G Martinez-Saucedo

Gusset plate connections to the ends of hollow structural section (HSS) members are regularly used in steel-framed buildings and roof trusses. Recent research on this connection type has indicated that current design recommendations for preventing tensile failure induced by shear lag may be overly conservative. This paper presents an experimental study on 13 gusset plate end connections to circular and elliptical HSS members under quasi-static tension and compression loadings. Current design proposals found in research studies and in design guides and specifications are compared with the experimental work. Various fabrication details for this connection type have been considered, and the influence of connection length, gusset plate orientation (in the tube long side versus short side), and distance between welds has been studied. In the experimental study, failure of all specimens under tensile loading was caused by circumferential fracture of the HSS or by tear-out of the HSS base material along the weld. The compression specimens failed by local buckling of the HSS at the connection end. A preferred static design approach for such connections is thus recommended.Key words: gusset plate, hollow section, tube, connection, round, elliptical, shear lag, tear-out failure.


2020 ◽  
Vol 91 (11) ◽  
pp. 314-319
Author(s):  
Denis Chemezov ◽  
◽  
Kirill Filatov ◽  
Irina Pavlukhina ◽  
Elena Bogomolova ◽  
...  

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yi Zhou ◽  
Meng Cui ◽  
Dequan Zhou ◽  
Xiaojia Wang ◽  
Xiao Fu

This paper presents an experimental study on the meso-structure change of clay using an innovative testing system. It aims to evaluate the tensile characteristics of clay. The testing system designed in this paper includes a tensile loading device, an image acquisition device, and an image processing program, which can collect and process the meso-structural images of the soil sample and predict the location of tensile fracture zone with a small preloading. The tests were conducted with three different observation zones, including the tensile fracture zone (Zone 1), the adjacent area of tensile fracture zone (Zone 2), and the areas away from the tensile fracture zone (Zone 3). The results show that the development of cracks is continuous but not linear until tensile failure in Zone 1, and the cracks emerge but stop developing in Zone 2 with the penetration of the cracks in Zone 1, while there is only an overall deviation without any cracks in Zone 3. The variety of mesostructural quantitative parameters in Zone 1 can be divided into three stages: stable stage, rapid change stage, and failure stage. The changes of parameters in Zone 2 show a similar law with those in Zone 1, but the variation is smaller due to the cessation of cracks. The parameters in Zone 3 essentially remain unchanged throughout the whole procedure. According to the test results, the whole stretching process of clay can be divided into the sprouting, the development, and the penetration of cracks.


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):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.


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