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 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.

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.

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.

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.

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.

scholarly journals Investigation on Dynamic Propagation Characteristics of In-Plane Cracks in PVB Laminated Glass Plates

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoqing Xu ◽  
Bohan Liu ◽  
Yibing Li
Keyword(s):  
Crack Propagation ◽  
Impact Loading ◽  
Crack Tip ◽  
Stress Waves ◽  
Critical Parameters ◽  
Propagation Mechanism ◽  
High Speed Photography ◽  
Laminated Glass ◽  
Propagation Characteristics ◽  
Crack Propagation Mechanism

Polyvinyl butyral (PVB) laminated glass has been widely used as an important component of mechanical and construction materials. Cracks on PVB laminated glass are rich in impact information, which contribute to its impact resistance design. In this paper, a three-dimensional (3D) numerical simulation model describing PVB laminated glass under impact loading is firstly established and validated qualitatively and quantitatively compared with the corresponding experimental results recorded by the high-speed photography system. In the meantime, the extended finite element method (XFEM) is introduced to analyze the crack propagation mechanism of laminated glass based on dynamic stress intensity factors (DSIFs) and propagations of stress waves. Parametric studies are then carried out to investigate the influence of five critical parameters, that is, plate dimension, crack length, impact energy, glass properties, and PVB properties, on crack propagation characteristics of laminated glass. Results show that the interaction between crack tip and stress waves as well as the propagations of stress waves corresponds to the fluctuations of DSIFs at crack tip. Both the structure and material variables are proven to play a very important role in glass cracking DSIFs and thus govern the crack propagation behavior. Results may provide fundamental explanation to the basic crack propagation mechanism on radial cracks in PVB laminated glass under impact loading conditions, thus to instruct its impact design improvement.

A Stress Intensity Factor Tracer

1985 ◽  
Vol 52 (2) ◽  
pp. 291-297 ◽  
Author(s):  
K.-S. Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Focal Plane ◽  
High Speed ◽  
Focal Point ◽  
Crack Tip ◽  
Theoretical Development ◽  
Significant Feature ◽  
High Speed Photography

A new optical method, Stress Intensity Factor Tracer (SIFT), has been developed. The device measures continuously the real-time stress intensity factor variation, K1(t), of a moving crack tip using a single, stationary photodetector. The method uses the fact that any variation in K1(t) leads to a change in the intensity of light, I(t), impinging on a fixed finite area, Γ, on the focal plane. The focal plane is defined as the plane on which initially parallel light rays transmitted through a transparent fracture specimen (or reflected from the surface of an opaque specimen) are focused by a converging lens. Provided that the light detecting area, Γ, excludes the focal point, a simple relation, I(t) =B[K1(t)]4/3, has been obtained for a K1-dominant field. The constant, B, is a product of several experimental parameters including a “shape factor” of the sampling area, Γ, where I(t) is measured. A significant feature of this method is that I(t) is independent of the location of the crack tip in the illuminated zone on the specimen plane. The technique may therefore be applied to dynamic fracture studies without using high-speed photography. Only the constant, B, becomes a function of crack velocity for the dynamic K1-field. This paper presents the theoretical development of the SIFT method, including the wave optics of the system. Experimental results supporting the theory are included.

Development of a dynamic decohesion criterion for subsonic fracture of the interface between two dissimilar materials

1995 ◽  
Vol 451 (1943) ◽  
pp. 711-736 ◽  
Keyword(s):  
Crack Growth ◽  
High Speed ◽  
Crack Tip ◽  
Dissimilar Materials ◽  
Complex Stress ◽  
High Speed Photography ◽  
Dynamic Crack ◽  
Shear Wave Speed ◽  
Loading Rates ◽  
Lateral Shearing Interferometer

We present findings of an experimental study of dynamic decohesion of bimaterial systems composed of constituents with a large material property mismatch. Poly-methylmethacrylate (PMMA)-steel and PMMA-aluminium bimaterial fracture specimens were used. Dynamic one-point bend loading was accomplished with a drop-weight tower device (for low and intermediate loading rates) or a high-speed gas gun (for high loading rates). High-speed interferometric measurements were made using the lateral shearing interferometer of coherent gradient sensing in conjunction with high-speed photography. Very high crack propagation speeds (terminal crack-tip speeds up to 1.5 c s PMMA , where c s PMMA is the shear wave speed of PMMA) and high accelerations (of about 10 7 g , where g is the acceleration of gravity) were observed and are reported. Issues regarding data analysis of the high-speed interferograms are discussed. The effects of near-tip three-dimensionality are also analysed. Dynamic complex stress factor histories are obtained by fitting the experimental data to available asymptotic crack-tip fields. A dynamic crack growth criterion for crack growth along bimaterial interfaces is proposed. In the subsonic regime of crack growth it is seen that the opening and shearing displacements behind the propagating crack tip remain constant and equal to their value at initiation, i.e. the crack retains a self-similar profile during crack growth at any speed. This forms the basis of the proposed dynamic interfacial fracture criterion.

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