Adhesion Thin Ductile Films Using Stressed Overlayers and Nanoindentation

2002 ◽  
Vol 750 ◽  
Author(s):  
M. J. Cordill ◽  
N. R. Moody ◽  
D. F. Bahr
Keyword(s):  
Fracture Toughness ◽  
Silicon Dioxide ◽  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Release Rate ◽  
Pure Shear ◽  
Interfacial Fracture ◽  
Shear Mode ◽  
Interfacial Fracture Toughness

ABSTRACTDifferently stressed films of tungsten on silicon dioxide have been studied to determine the interfacial fracture toughness and the Mode I fracture energy release rate of tungsten on glass. Tungsten films with a low compressive stress (less than 1GPa) had nanoindentation tests performed on them to induce buckling. Using mechanics based models and the dimensions of the buckles the fracture energy release rate and the phase angle of loading (Ψ) were calculated to be between 3.8 and 13 J/m2. By varying the residual stress in the film it was possible to examine regions of pure shear (Mode II) interfacial fracture as well as mixed mode interfacial fracture toughness of this system. A similar tungsten film was then used as stressed overlayer on sputtered Pt films on silicon dioxide to determine the fracture energy release rate. Nanoindentation was required to induce buckling, as the overlayer alone did not cause spontaneous buckling. The stressed overlayer method and nanoindentation were used to determine the interfacial toughness of the Pt/silica system to be 1.4 J/m2.

Fracture Toughness Measurement of Asphalt Concrete by Nanoindentation

2017 ◽  
Author(s):  
Zafrul Khan ◽  
Hasan M. Faisal ◽  
Rafiqul Tarefder
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Release Rate ◽  
Asphalt Concrete ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Macro Scale ◽  
Load Displacement

Fracture toughness and fracture energy release rate are two important parameters to understand the crack propagation within any material. Fracture toughness of asphalt concrete (AC) is vital to explain the fatigue cracking and low temperature cracking of asphalt pavement. These two types of distresses are still unsolved issues for asphalt researchers. Measuring fracture toughness of AC is not a new phenomenon. Recently, researchers have used several techniques to measure the fracture toughness of AC. Tests like semi-circular bending (SCB) and disk-shaped compact specimen (DCT) testing have been used to measure the fracture toughness of the AC. From the SCB or DCT tests, past researchers have shown that crack in AC propagates through mainly binder and mastic phase. All these conventional tests are carried out in macro scale. It is important to understand that before propagation of these macro scale cracks, the cracks initiates at the nano/micro scale level. With the increment of the loads these nanoscale cracks become macro scale cracks and propagates through the sample. Therefore, it is important to understand the cracks at nanoscale. In this study, nanoindentation test was introduced to measure the fracture toughness of the asphalt concrete. In a nanoindentation test, the sample surface is indented with a loaded indenter. For this test, Berkovich indenter with load control method was used. A field cored asphalt concrete sample was used for this study. The sample was collected by coring at interstate 40 (I-40) near Albuquerque, New Mexico. The sample was field aged for four years. The maximum load applied in this study was 5-mn and the unloading was done at a faster rate than the loading rate. From the load-displacement curves of the nanoindentation tests, fracture toughness of the samples was measured. The unloading curve of the nanoindentation test was further used to obtain reduced modulus of the asphalt concrete using Oliver-Pharr method. In this study, fracture energy is thought of as a portion of irreversible energy. This irreversible energy is comprised of plastic energy and energy required for propagation of crack. By analyzing the load displacement curve along with the maximum indentation depth, energy release rate and mode I fracture toughness of asphalt concrete was measured.

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.

Test Study of Fracture Mechanical Properties of Reactive Powder Concrete with Additives

2014 ◽  
Vol 904 ◽  
pp. 3-6 ◽  
Author(s):  
Zhi Gang Yin
Keyword(s):  
Mechanical Properties ◽  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Release Rate ◽  
Fracture Behavior ◽  
Fracture Model ◽  
Reactive Powder Concrete ◽  
Critical Crack Length ◽  
Reactive Powder

The different influencing regular of fly-ash fractiontype of fibre (steel fibre and polypropylene fibre) and fibre fraction on the mechanical property and fracture behavior of Reactive Powder Concrete (PRC) are studied. Fracture mechanical properties of RPC is researched in double-K fracture model and fracture energy release rate G . Test results show that the crack propagation of RPC with steel fibers is limited. Its fracture toughness and pre-critical crack length is largely enhanced. Double-K fracture model and fracture energy release rate G are consistent with describing the fracture behavior of RPC.

Miniature bulge test and energy release rate in HIPed aluminum/aluminum interfacial fracture

2018 ◽  
Vol 120 ◽  
pp. 179-198 ◽  
Author(s):  
C. Liu ◽  
M.L. Lovato ◽  
K.D. Clarke ◽  
D.J. Alexander ◽  
W.R. Blumenthal
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Interfacial Fracture ◽  
Bulge Test

Modified Decohesion Test (MDT) for Interfacial Fracture Toughness Measurement in Microelectronic/MEMS Applications

2002 ◽  
Author(s):  
Mitul B. Modi ◽  
Suresh K. Sitaraman
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Fracture Toughness ◽  
Energy Release ◽  
Physical Vapor Deposition ◽  
Interfacial Fracture ◽  
Interfacial Fracture Toughness ◽  
Testing Methods ◽  
Structural Variations ◽  
Metal Thin Film

Delamination of intrinsically or residually stressed thin films is commonly encountered in microelectronics and MEMS systems. Thin films typically accrue stresses through micro structural variations caused by physical vapor deposition, thermally induced stresses imposed due to thermal mismatch, and/or extrinsically introduced forces. These stresses can reach upwards of 1 GPa and can easily exceed the strength of the metal thin film interface. Knowledge of the interfacial fracture toughness (Γ) is necessary to predict if delamination will occur. However, measuring Γ is a challenge for thin film interfaces. Typical testing methods such as bimaterial cantilever, microscratch, peel, bulge, or edge lift-off are limited to organic films, cause complex stress fields, can only measure a single mode mix, or cannot achieve the large energy release rates typical of metal thin film interfaces. A new approach based on the decohesion test, called the modified decohesion test (MDT), eliminates these shortcomings of current testing methods. In this approach, a highly stressed super layer is used to drive delamination and “tune-in” the mode mix at the crack tip. Since the deformations remain elastic, a mechanics-based solution can be used to correlate test parameters to the energy release rate. Common IC fabrication techniques are used to prepare the sample and execute the test, thereby making the test compatible with current microelectronic or MEMS facilities. Varying the crack surface area rather than the energy in the super layer allows the ability to bound Γ using a single test wafer providing a 90% savings in resources and 95% savings in time. Other modifications allow application of the method to highly chemically reactive metals and decrease the sample preparation time. Design, preparation, and execution of the MDT are presented. Results of finite element models are used to validate the approach. Results are shown for a Ti/Al2O3 interface.

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.

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