Crack propagation and divergence phenomena observed by Caustics method in tempered glass

2021 ◽  
pp. 1-18
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Crack Propagation ◽  
High Speed ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Glass Plates ◽  
The Difference ◽  
Caustics Method ◽  
Thick Glass

High speed photography by Caustics method using Cranz-Schardin camera was studied for crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. Two types of bifurcation and branching as the crack divergence could be observed and clarified even in 10 mm thick tempered glass. The difference of the shadow spot sizes between bifurcation type and branching type could be confirmed.

New crack generation phenomena by crack collision in 10 mm thick tempered glass

2021 ◽  
pp. 1-13
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
High Speed ◽  
Crack Tip ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Crack Generation ◽  
Caustics Method ◽  
Thick Glass ◽  
Collision Angle

High speed photography by Caustics method using Cranz–Schardin camera was used to study crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. New crack generation by two crack collision was observed. Regarding the presence/absence of new cracks, the dependence of the two cracks on the collision angle was confirmed. Considering that it is based on the synthesis of stress 𝜎CR generated at the crack tip, tensile stress necessary for the generation of new cracks could be created.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

A study of the collapse of arrays of cavities

1988 ◽  
Vol 190 ◽  
pp. 409-425 ◽  
Author(s):  
J. P. Dear ◽  
J. E. Field
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
High Speed Photography ◽  
Cavitation Damage ◽  
Major Mechanism ◽  
Collapse Mechanisms ◽  
Multiple Jets ◽  
Circular Holes ◽  
Schlieren Photography ◽  
Thick Glass

This paper describes a method for examining the collapse of arrays of cavities using high-speed photography and the results show a variety of different collapse mechanisms. A two-dimensional impact geometry is used to enable processes occurring inside the cavities such as jet motion, as well as the movement of the liquid around the cavities, to be observed. The cavity arrangements are produced by first casting water/gelatine sheets and then forming circular holes, or other desired shapes, in the gelatine layer. The gelatine layer is placed between two thick glass blocks and the array of cavities is then collapsed by a shock wave, visualized using schlieren photography and produced from an impacting projectile. A major advantage of the technique is that cavity size, shape, spacing and number can be accurately controlled. Furthermore, the shape of the shock wave and also its orientation relative to the cavities can be varied. The results are compared with proposed interaction mechanisms for the collapse of pairs of cavities, rows of cavities and clusters of cavities. Shocks of kbar (0.1 GPa) strength produced jets of c. 400 m s−1 velocity in millimetre-sized cavities. In closely-spaced cavities multiple jets were observed. With cavity clusters, the collapse proceeded step by step with pressure waves from one collapsed row then collapsing the next row of cavities. With some geometries this leads to pressure amplification. Jet production by the shock collapse of cavities is suggested as a major mechanism for cavitation damage.

Partial Destruction of Reinforced Concrete Wall by Small Blasting

2014 ◽  
Vol 566 ◽  
pp. 268-273
Author(s):  
Kana Nishino ◽  
Shiro Kubota ◽  
Yuji Wada ◽  
Yuji Ogata ◽  
Norio Ito ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
High Speed Photography ◽  
Single Shot ◽  
Concrete Wall ◽  
Strain Measurements ◽  
Crater Size ◽  
Reinforced Concrete Wall ◽  
The Difference ◽  
Partial Destruction

The crater on the reinforced concrete wall generated by the explosion of a few grams of Composition C4 explosive was investigated. A series of the single-shot blast experiment were conducted. The structural specimens for the reinforced concrete wall (750 mm × 750 mm × 250 mm) were used for estimation of the crater size. The diameter of the borehole was fixed 16 mm, and the length of borehole was varied to generate the various size of crater. The amount of explosive was also varied from 3.0 to 8.0 g. The effect of the length of the borehole to the crater depth was examined. High-speed photography was used to observe the fracture process of the crater. As the results, in the difference of the side where the crater was generated, the situation of crushing was different. The strain measurements were also conducted.

Crack Propagation in Freshwater and Saline Ice

1999 ◽  
Vol 578 ◽  
Author(s):  
Patrick J. Donovan ◽  
Masahiko Arakawa ◽  
Victor Petrenko
Keyword(s):  
Crack Propagation ◽  
Crack Velocity ◽  
High Speed ◽  
Acoustic Emissions ◽  
Crack Tip ◽  
High Speed Photography ◽  
Propagation Time ◽  
Reliable Technique ◽  
Resistance Method ◽  
Freshwater Ice

AbstractCrack propagation in columnar saline and freshwater ice has been investigated with high-speed photography, acoustic emission detection and the resistance method. High-speed photography was found to be a single reliable technique. The resistance method proved effective for freshwater ice samples, but not for saline ice samples due to the presence of conductive fluid inclusions. Acoustic emissions pinpointed the moment of crack initiation, but did not correspond to the crack propagation time. Crack velocity has been characterized over a temperature range of -5°C to -30 °C for freshwater and saline ice. Freshwater ice exhibited an overall average velocity of 198 m/s, and did not vary with temperature. Crack velocity in saline ice demonstrated temperature dependence, increasing from an average of 86 m/s in the -5°C to -20°C range, to 131 m/s at -30°C. The crack velocity was also shown to have a general dependence on fracture toughness K' of the material, however, the microstructural variation between samples is also shown to influence significantly the crack behavior in both saline and freshwater ice. Nonuniform crack tip advance and crack reorientation were observed as crack slowing mechanisms in freshwater ice, while in saline ice fracture crack tip blunting on voids greatly reduced average crack velocities.

Observation of crack propagation in saline ice and freshwater ice with fluid inclusion

2003 ◽  
Vol 81 (1-2) ◽  
pp. 159-166
Author(s):  
M Arakawa ◽  
V F Petrenko
Keyword(s):  
Crack Propagation ◽  
Electrical Resistance ◽  
Crack Velocity ◽  
High Speed ◽  
High Speed Photography ◽  
Low Density ◽  
Conductive Liquid ◽  
Freshwater Ice ◽  
Maximum Crack ◽  
Very High

A key process of crack propagation in saline ice is the interaction between the crack and fluid inclusions. We observed their interaction in freshwater ice using very high-speed photography (VHSP) and found that the low-density fluids (air and inert liquid, Fluorinert, 1.78 g/cm3) could not impede the crack effectively, interrupting the propagation for less than 10 µs. The high-density liquid mercury, (13.8 g/cm3) impeded the crack more effectively, stalling the development of the crack for more than 20 µs. The crack velocity in saline ice was measured using two different methods: electrical resistance method (ERM) and VHSP. These two methods returned very different mean velocities, 15 m/s for the ERM and 250 m/s for the VHSP. We found that in ice with conductive liquid inclusions, the ERM measured the time it took to break liquid bridges stretched across a crack rather than the crack velocity. Results from the VHSP show that the maximum crack velocity in saline ice was 500 m/s, which is one-half of that found in freshwater ice. From our results using freshwater ice with inclusions, we conclude that liquid inclusions in saline ice may play a role in this retardation. PACS No.: 62.20Mk

The Measurement of the Fatigue Crack-Tip Displacement and Strain Fields under High Frequency Resonant Loading Applying DIC Method

2015 ◽  
Vol 710 ◽  
pp. 83-90
Author(s):  
Hong Li Gao ◽  
Wei Jiang ◽  
Huan Liu ◽  
Huan Bin Zheng ◽  
Hui Liu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
High Frequency ◽  
High Speed ◽  
Loading Condition ◽  
Crack Tip ◽  
Dynamic Strain ◽  
High Speed Photography ◽  
Stress Cycle ◽  
Strain Fields

In order to measure the displacement and strain field in the fatigue crack tip area of CT specimens under high frequency resonant loading condition in the fatigue crack propagation test, a method based on the digital image correlation (DIC) and digital high-speed photography technology are proposed in this paper. First, a series of digital speckle images of CT specimen under sinusoidal alternating load were collected by digital high-speed photography equipment, the displacement and strain fields within the region of crack tip in each image were calculated by DIC. The sinusoidal changing strain curve has been obtained by the least square sine wave fitting method, and the characteristic parameters of sinusoidal strain are calculated, such as the amplitude, frequency, phase, mean load . The images of characteristic position in one stress cycle were obtained by comparing the fitted sine curve of strain with the corresponding speckle images. Finally, the dynamic strain gauge was used to measure the strain at crack tip point during one stress cycle, and the accuracy and feasibility of DIC method were verified by the experimental results. The study result presented in this paper will supply a foundation for exploring the crack propagation law and measuring the fatigue crack growth parameters under high frequency resonant loading condition further.

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