Effect of liquid nitrogen freeze-thaw cycle on fracture toughness and energy release rate of saturated sandstone

2021 ◽  
pp. 108066
Author(s):  
Peng Hou ◽  
Shanjie Su ◽  
Xin Liang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Liquid Nitrogen ◽  
Release Rate ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The Spherical Indentation Approach for Fracture Toughness Evaluation: A Study Based on the Energy Release Rate

2018 ◽  
Author(s):  
Tairui Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Mechanism ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Material Damage ◽  
Fracture Tests

In this study, we investigated the drawbacks of previous studies regarding the evaluation of fracture toughness from spherical indentation tests (SITs). This was achieved by an examination of the material damage mechanism during indentation tests, uniaxial tensile tests, and Mode I/II fracture tests. A new approach based on the energy release rate was proposed in this study to evaluate the fracture toughness of ductile metals. Scanning electron microscope (SEM) observations revealed that the mechanism for material damage during an indentation test was different with the material damage in uniaxial tensile tests and Mode I fracture tests, but similar to that in Mode II fracture tests. Thus, the energy release rate during SITs should be correlated with JIIC. Compared with previous studies, this new proposed method was more consistent with the actual damage mechanism and did not rely on the specific critical damage values. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the maximum error from this energy release rate-based approach was no more than 13% when compared with their conventional counterparts (compact tension tests), and thus can meet the precision requirement of engineering applications.

On the Effect of Latent Heat on the Fracture Toughness of Pseudoelastic Shape Memory Alloys

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Theocharis Baxevanis ◽  
Chad M. Landis ◽  
Dimitris C. Lagoudas
Keyword(s):  
Fracture Toughness ◽  
Shape Memory Alloys ◽  
Energy Release Rate ◽  
Shape Memory ◽  
Energy Release ◽  
Latent Heat ◽  
Release Rate ◽  
Crack Tip ◽  
Thermomechanical Coupling ◽  
Adiabatic Conditions

A finite element analysis of steady-state crack growth in pseudoelastic shape memory alloys under the assumption of adiabatic conditions is carried out for plane strain, mode I loading. The crack is assumed to propagate at a critical level of the crack-tip energy release rate and the fracture toughness is obtained as the ratio of the far-field applied energy release rate to the crack-tip critical value. Results related to the influence of latent heat on the near-tip stress field and fracture toughness are presented for a range of parameters related to thermomechanical coupling. The levels of fracture toughness enhancement, associated with the energy dissipated by the transformed material in the wake of the growing crack, are found to be lower under adiabatic conditions than under isothermal conditions [Baxevanis et al., 2014, J. Appl. Mech., 81, 041005]. Given that in real applications of shape memory alloy (SMA) components the processes are usually not adiabatic, which is the case with the lowest energy dissipation during a cyclic loading–unloading process (hysteresis), it is expected that the actual level of transformation toughening would be higher than the one corresponding to the adiabatic case.

The characteristics of dynamic fracture toughness and energy release rate of rock under impact

Measurement ◽  
2019 ◽  
Vol 147 ◽  
pp. 106884 ◽  
Author(s):  
Peng Ying ◽  
Zheming Zhu ◽  
Fei Wang ◽  
Meng Wang ◽  
Caoyuan Niu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Dynamic Fracture ◽  
Release Rate ◽  
Dynamic Fracture Toughness

Experimental study on the effect of interface fiber orientation and utilized delamination initiation techniques on fracture toughness of glass/epoxy composite laminates

2016 ◽  
Vol 35 (23) ◽  
pp. 1722-1733 ◽  
Author(s):  
Masood Nikbakht ◽  
Hossein Hosseini Toudeshky ◽  
Bijan Mohammadi
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Composite Laminates ◽  
Standard Procedure ◽  
Damage Zone ◽  
Critical Energy ◽  
Critical Energy Release Rate ◽  
Interface Layers

Critical energy release rate for delamination initiation in composites as a material property, supposed to be independent from non-material variables. However, a thorough literature review presented in this study shows that in many cases it may vary with the variation of layup configuration or geometrical and dimensions. This study is aimed to investigate the effect of interface layers orientation on fracture toughness by eliminating the other influential parameters such as stacking sequence, by selecting the anti-symmetric layup configuration of Double Cantilever Beam, [Formula: see text], in which θ will be 0°, 30°, 45° and 60°. The energy release rates data have been calculated using different criteria and techniques to obtain the load and displacement at initial crack growth and the results were compared with the standard methods. The damage zone near the crack tip is also illustrated before and after the crack propagation by microscopic images of delamination front, and discussed for all investigated interface fiber angles. Experimental results show that the effect of interface layers orientation on fracture toughness of the investigated layup configurations based on the nonlinear technique as a standard procedure is negligible while other techniques show a considerable changes in the calculated energy release rate with the increase of interface layers angle from zero to 60 degrees.

scholarly journals Experimental Investigation of the Size Effect of the Mode I Static Fracture Toughness of Limestone

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Sheng Zhang ◽  
Longfei Wang ◽  
Mingzhong Gao
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Release Rate ◽  
Construction Materials ◽  
Reference Method ◽  
Dimensionless Energy ◽  
Static Fracture

To study the size effect of the fracture toughness of notched semicircular bend (NSCB) specimens, the dimensionless energy release rate equation of the NSCB specimen was deduced on the basis of the Bažant energy release rate. The influence of the crack length and the specimen size on the fracture toughness was analyzed. The Bažant scale equation was obtained using the International Union of Laboratories and Experts in Construction Materials, Systems, and Structures (RILEM) method. Finally, the Bažant equation was used to analyze the fracture toughness of an NSCB specimen with a radius of 75 mm, and the degree of variation was predicted. The results show that a longer fracture is correlated with a lower fracture toughness value for the same sample size and that a larger specimen radius is correlated with a higher fracture toughness value for the same crack length. The obtained Bažant equation correctly reflects the scale law of the fracture toughness of the NSCB specimen and provides highly accurate predictions of the fracture toughness of large specimens, with an error of not more than 3%. The results obtained in this study provide a new reference method and theoretical basis for the future testing work.

scholarly journals Influence of Freeze-Thaw Cycles on Engineering Properties of Tonalite: Examples from China

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Su-Ran Wang ◽  
You-Liang Chen ◽  
Jing Ni ◽  
Mu-Dan Zhang ◽  
Heng Zhang
Keyword(s):  
Fracture Toughness ◽  
Young’S Modulus ◽  
Minimum Temperature ◽  
Young's Modulus ◽  
Physical And Mechanical Properties ◽  
Frost Damage ◽  
Engineering Properties ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The deterioration of the physical and mechanical properties of tonalites subjected to freeze-thaw cycling under three different temperature ranges was explored using several experimental techniques. Uniaxial compression and three-point bending tests were conducted on untreated and treated tonalite specimens. Clear decreases in uniaxial compressive strength (UCS), Young’s modulus, and fracture toughness were observed in tonalite specimens with frost damage. Although Young’s modulus and fracture toughness did not show clear decreases as the minimum temperature of the freeze-thaw cycle decreased from −30°C to −50°C, the UCS decreased almost linearly. The macromechanical characteristics of the tonalites can be explained by changes in mineral content and microstructure. The intensity of X-ray diffraction (XRD) peaks of minerals in tonalites that had not been freeze-thaw cycled were approximately 10 to 20 times higher than the peaks for the specimens subjected to freeze-thaw cycling, implying that the internal structure of tonalite is less compact after frost damage. The microstructures of the tonalite specimens were also examined using scanning electron microscopy (SEM). Increased amounts of fragmentation and breaking of structural planes were observed as the minimum temperature of the freeze-thaw cycle decreased.

ENERGY RELEASE RATE OF INTERFACE DELAMINATION BETWEEN A THIN COATING AND AN ELASTIC SUBSTRATE

2008 ◽  
Vol 22 (04) ◽  
pp. 407-416
Author(s):  
X.-Y. DUAN ◽  
X.-F. LI
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Elastic Beam ◽  
Elastic Substrate ◽  
Cross Sectional ◽  
Closed Form Solutions ◽  
Interface Delamination ◽  
Properties Of Materials

The mechanical properties of materials such as elastic modulus, hardness, and fracture toughness, can be measured by nanoindentation. For a thin film coated on an elastic substrate, the cross-sectional nanoindentation technique can decrease the influence of plastic deformation around the nanoindenter apex on fracture toughness for interface delamination. Considering the effect of the elastic substrate, the theory of an elastic beam bonded to an elastic foundation is further developed to obtain the energy release rate of interfacial debonding. Explicit closed-form solutions are determined, and the influence of the substrate on the energy release rate is shown graphically.

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