A Method of Fracture Toughness Measurement and Effect of Partial Annealing on Monolithic Thick Cold Sprayed Aluminum 6061 Deposits

2016 ◽  
Author(s):  
B. Bangstein ◽  
M. Ellingsen ◽  
N. Scholl
Keyword(s):  
Fracture Toughness ◽  
Cold Spray ◽  
Fracture Behavior ◽  
Compact Tension ◽  
Elastic Plastic ◽  
Material Deposition ◽  
Fracture Toughness Measurement ◽  
Potential Applications ◽  
Spray Deposit ◽  
Metal Layers

Cold spray is a solid-state material deposition method that can create thick (>10mm) metal layers that adhere metallurgically to a base part or a substrate. Numerous potential applications exist, such as returning worn mechanical parts to their original dimension, extending their service life. For fatigue applications the fracture properties of cold spray deposited material must be known but little to no literature has been found on the fracture behavior of cold spray deposited material alone, which prompted the study presented here. Fracture toughness specimens were manufactured by depositing thick cold-sprayed layers of powdered aluminum 6061 onto an aluminum 6061 substrate using N2 as the carrier gas. The substrate was then machined away, and monolithic miniature compact tension fracture toughness specimens were machined from the cold spray deposit itself, following ASTM E-1820. The fracture behavior of the cold sprayed material was then experimentally determined using the elastic-plastic J-resistance method for compact test specimens described in ASTM E-1820. Two specimen conditions were successfully tested, “as-sprayed” and “partially annealed”. The results are that the Mode-I elastic-plastic stress intensity factor JI has been successfully measured for cold-spray deposited material alone, and that partially annealing a cold-spray deposit can dramatically increase its fracture toughness.

Experimental evaluation of fracture properties of bovine hip cortical bone using elastic–plastic fracture mechanics

2021 ◽  
pp. 1-10
Author(s):  
Waseem Ur Rahman ◽  
Rafiullah khan ◽  
Noor Rahman ◽  
Ziyad Awadh Alrowaili ◽  
Baseerat Bibi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Plastic Deformation ◽  
Fracture Mechanics ◽  
Cortical Bone ◽  
Elastic Deformation ◽  
Compact Tension ◽  
J Integral ◽  
Elastic Plastic ◽  
American Society ◽  
Fracture Specimens

BACKGROUND: Understanding the fracture mechanics of bone is very important in both the medical and bioengineering field. Bone is a hierarchical natural composite material of nanoscale collagen fibers and inorganic material. OBJECTIVE: This study investigates and presents the fracture toughness of bovine cortical bone by using elastic plastic fracture mechanics. METHODS: The J-integral was used as a parameter to calculate the energies utilized in both elastic deformation (Jel) and plastic deformation (Jpl) of the hipbone fracture. Twenty four different types of specimens, i.e. longitudinal compact tension (CT) specimens, transverse CT specimens, and also rectangular unnotched specimens for tension in longitudinal and transverse orientation, were cut from the bovine hip bone of the middle diaphysis. All CT specimens were prepared according to the American Society for Testing and Materials (ASTM) E1820 standard and were tested at room temperature. RESULTS: The results showed that the average total J-integral in transverse CT fracture specimens is 26% greater than that of longitudinal CT fracture specimens. For longitudinal-fractured and transverse-fractured cortical specimens, the energy used in the elastic deformation was found to be 2.8–3 times less than the energy used in the plastic deformation. CONCLUSION: The findings indicate that the overall fracture toughness measured using the J-integral is significantly higher than the toughness calculated by the stress intensity factor. Therefore, J-integral should be employ to compute the fracture toughness of cortical bone.

Interlaminar and Intralaminar Fracture Behavior of Carbon Fiber Reinforced Polymer Composites

2016 ◽  
Vol 713 ◽  
pp. 325-328 ◽  
Author(s):  
Sandip Haldar ◽  
Claudio S. Lopes ◽  
Carlos Gonzalez
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Fracture Behavior ◽  
Compact Tension ◽  
Mode Ii ◽  
Fiber Reinforced ◽  
Fiber Reinforced Polymer Composites ◽  
Mode Ii Fracture Toughness ◽  
Carbon Fiber Reinforced ◽  
Woven Reinforcement

Interlaminar and intralaminar fracture behavior of carbon fiber reinforced composites have been experimentally studied. Unidirectional, woven reinforcement and thermoplastic and thermoset polymer matrix laminates have been characterized using double cantilever beam (DCB) and end notch flexure (ENF) specimens for Mode-I and Mode-II fracture toughness, respectively and compact tension (CT) specimens for intralaminar fracture. AS4/PEEK, AS4/8552 and AGP193PW/8552 laminates have been characterized in this study. The fracture toughness determined from the experimental data could be related to the constituents and reinforcements. It has been observed between the two UD laminates, AS4/PEEK exhibit higher fracture resistance under both interlaminar and intralaminar fracture. Woven reinforcement is found to show higher mode-II interlaminar fracture toughness.

Influence of Microstructure on the Fracture Mechanism and Mechanical Behavior in 7010 and 7150 Alloys

2006 ◽  
Vol 324-325 ◽  
pp. 463-466
Author(s):  
Xi Gang Fan ◽  
Da Ming Jiang ◽  
Chang Li Wang ◽  
Yong Liang Guo ◽  
Xing Qiu Liu
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Fracture Behavior ◽  
Compact Tension ◽  
Transgranular Fracture ◽  
Plane Strain Fracture Toughness ◽  
Ageing Treatment ◽  
Cu Alloys ◽  
Intermetallic Particles ◽  
Strain Fracture

The effect of ageing treatment and coarse intermetallic particles on the compromise between the toughness and the yield strength of 7010 and 7150 aluminum alloys (Al-Zn-Mg-Cu alloys) are investigated. Plane-strain fracture toughness tests were performed on the compact-tension specimens of L-T orientation. The fracture toughness of 7010 alloy was higher than that of 7150 alloy at the same ageing treatment. The 7150 alloy contain a greater amount of coarse Cu-bearing particles, which deteriorate the fracture behavior and decrease the ageing hardening ability of the alloy. The toughness of the both alloys increased greatly for the overaged condition as compared to that for the T6 condition. Two dominant mechanisms of failure occur: microvoid-induced transgranular fracture and intergranular fracture modes, and the former becomes more important in the overaged ageing conditions.

Comparison of J-Integral Values and J-R Curves Between Carbon Steel Compact Tension Specimen and Pipe Specimen

2004 ◽  
Author(s):  
Masahiro Takanashi ◽  
Satoshi Izumi ◽  
Shinsuke Sakai ◽  
Naoki Miura
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Crack Initiation ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Small Scale ◽  
Outer Diameter ◽  
J Integral ◽  
Tension Specimen ◽  
Elastic Plastic

In the present study, the transferability of elastic-plastic fracture toughness from a small-scale to a large-scale specimen was experimentally confirmed for carbon steel pipe with mild toughness. Fracture toughness tests were carried out on a pipe specimen 318.5 mm in outer diameter, 10.3 mm in thickness and having a through-wall crack, and also on a compact tension specimen 9.7mm in thickness, 25.4 mm in width, that had been cut out from the pipe specimen. Test results indicated the J-integral value of the pipe specimen at the crack initiation to be nearly twice that of the CT specimen. Finite element analysis conducted on the two specimens indicated this difference to arise primarily from the constraint near the crack front. Discussion was also made of the effects of crack orientation on elastic-plastic fracture toughness of CT specimens. The J-integral value at crack initiation in the specimen whose crack direction coincided with the pipe axial was found to be almost 54 % more than for specimens whose crack direction was circumferential.

Effects of Hydride Morphology and Test Temperature on Fracture Toughness of Zr-2.5Nb Pressure Tube Material

2009 ◽  
Author(s):  
Jun Cui ◽  
Gordon K. Shek
Keyword(s):  
Fracture Toughness ◽  
Test Temperature ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Fracture Initiation ◽  
Compact Tension ◽  
Pressure Tube ◽  
Primary Coolant ◽  
Tube Section ◽  
Pressure Tubes

CANDU® reactor uses Zr-2.5Nb alloy pressure tubes as the primary coolant containment. Fracture toughness properties of the pressure tubes are required for evaluation of fracture initiation and leak-before-break. This paper presents an experimental study on the effects of hydride morphology and test temperature on axial fracture toughness of a cold-worked, unirradiated Zr-2.5Nb pressure tube. Compact tension specimens were prepared from one tube section which contained as-received hydrogen concentration and another section which was electrolytically hydrided to 70 ppm hydrogen. Reoriented hydrides were formed in the hydrided tube section in ten thermal cycles under an applied tensile hoop stress of 160 MPa. The hydride morphologies were characterized by a parameter referred to as the hydride continuity coefficient (HCC), which provided a measure of the extent to which the hydrides were reoriented with respect to the applied stress direction. Partially reoriented hydrides with HCC between 0.3–0.4 were formed under the stress and temperature cycles used to precipitate the hydrides. J-R curves were generated to characterize the fracture behavior of the specimens tested at five different temperatures: 25°C (room temperature), 100°C, 150°C, 200°C and 250°C. Test results indicate that, for the as-received specimens, the fracture toughness is relatively high at room temperature and not significantly affected by the test temperature between room temperature and 250°C. For the 70 ppm hydrided specimens containing partially reoriented hydrides, the fracture toughness is significantly lower than that of the as-received specimens at room temperature. At 100°C, the fracture toughness is higher than that at room temperature but the average value is still lower than that of the as-received specimens. The specimens exhibit either brittle or ductile fracture behavior with a sharp transition to an upper-shelf toughness value. At 150°C, the specimens achieve an upper-shelf toughness level. Between 150°C and 250°C, the fracture toughness is similar to that of the as-received specimens and not affected by the reoriented hydrides.

J041035 Fracture Toughness Measurement of 4N Aluminium Compact-Tension Specimens

2012 ◽  
Vol 2012 (0) ◽  
pp. _J041035-1-_J041035-4
Author(s):  
Hiroaki EGAWA ◽  
Wataru IKEHARA ◽  
Hiroyuki KATO ◽  
Kazuaki SASAKI
Keyword(s):  
Fracture Toughness ◽  
Compact Tension ◽  
Fracture Toughness Measurement ◽  
Toughness Measurement

scholarly journals Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 244 ◽  
Author(s):  
Byeong Seo Kong ◽  
Ji Ho Shin ◽  
Changheui Jang ◽  
Hyoung Chan Kim
Keyword(s):  
Fracture Toughness ◽  
Structural Integrity ◽  
Compact Tension ◽  
Fracture Toughness Test ◽  
Pure Tungsten ◽  
Test Environment ◽  
Toughness Test ◽  
Fracture Toughness Measurement ◽  
Ar Gas ◽  
Toughness Measurement

The evaluation of fracture toughness of pure tungsten is essential for the structural integrity analysis in a fusion reactor. Therefore, the accurate quantification of fracture toughness of tungsten alloys is needed. However, due to the inherent brittleness of tungsten, it is difficult to introduce a sharp fatigue pre-crack needed for the fracture toughness test. In this study, a novel fatigue pre-cracking method was developed and applied to the small-sized disc-type compact tension (DCT) specimens of double-forged pure tungsten. To overcome the brittleness and poor oxidation resistance, a low-frequency tensile fatigue pre-cracking was performed at 600 °C in Ar environment, which resulted in the introduction of a sharp pre-crack to DCT specimens. Then, fracture toughness tests were conducted at room temperature (RT), 400 °C, and 700 °C in air and Ar gas environments using as-machined and pre-cracked DCT specimens. At RT and 400 °C, the test environment and crack tip radius did not affect the fracture toughness measurement. However, at 700 °C, the Ar gas environment and the presence of a sharp fatigue pre-crack resulted in a decrease in the measured fracture toughness. Thus, it was suggested that, for the conservative fracture toughness measurement of pure tungsten, fatigue pre-cracking and fracture toughness test should be performed in an inert environment, especially for high-temperature tests.

Interfacial Fracture Toughness Measurement of a Ti/Si Interface

2004 ◽  
Vol 126 (3) ◽  
pp. 301-307 ◽  
Author(s):  
Mitul Modi ◽  
Suresh K. Sitaraman
Keyword(s):  
Fracture Toughness ◽  
Interfacial Fracture ◽  
Interfacial Fracture Toughness ◽  
Thermally Induced ◽  
Adhesive Layers ◽  
Available Energy ◽  
Fracture Toughness Measurement ◽  
Test Parameters ◽  
Metal Layers ◽  
Toughness Measurement

Titanium adhesive layers are commonly used in microelectronic and MEMS applications to help improve the adhesion of other metal layers to a silicon substrate. Such Ti/Si interfaces could potentially delaminate under externally applied mechanical loads, thermally induced stresses, or process-induced intrinsic stresses or a combination of these different loads. In order to design against delamination, knowledge of the interfacial fracture toughness of the Ti/Si interface is necessary. However, interfacial fracture toughness data for such interfaces is not widely available in the open literature, in part due to the difficulty in measuring the strength of thin film interfaces. The Modified Decohesion Test (MDT), a new test developed by the authors, has been used to characterize the mode mix dependent interfacial fracture toughness of a Ti/Si interface. In this approach, a highly stressed super layer is used to drive delamination and generate any mode mix at the crack tip. MDT uses the change in crack surface area to vary the available energy per unit area for crack growth and thus to bound the interfacial fracture toughness. Therefore, this technique uses a single sample to measure the interfacial fracture toughness. 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. Using the MDT, interfacial fracture toughness (Γ) bounds were found for a Ti/Si interface at three mode mixes. At a mode mix of 19.5 deg, 5.97J/m2⩽Γ⩽7.87J/m2, at a mode mix of 23 deg, 9.32J/m2⩽Γ⩽10.42J/m2, and at a mode mix of 30 deg, 12.70J/m2⩽Γ⩽17.02J/m2.

A Numerical Study on Fracture Toughness of CANDU Pressure Tube

2017 ◽  
Author(s):  
Elisabeth Keim ◽  
Tomas Nicak ◽  
Bogdan Wasiluk
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Numerical Study ◽  
Compact Tension ◽  
Operating Conditions ◽  
Pressure Tube ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Two Phase ◽  
Pressure Tubes

CANDU pressure tubes carry nuclear fuel and belong to the primary heat transport system. They are fabricated from cold-worked Zr-2.5Nb alloy prone to deuterium ingress under normal operating conditions. Increased hydrogen equivalent concentration and reactor pressure-temperature transients result in development of a brittle phase, hydride, changing mechanical behavior. The hydride downgrades fracture toughness properties in the transition region and reduces material ductility. Canadian Nuclear Safety Commission founded a two-phase project to improve understanding of the parameters governing fracture toughness properties and load carrying capacity of Zr-2.5Nb pressure tubes with elevated hydrogen equivalent concentrations. This paper presents preliminary results obtained in the first phase. The fracture behavior of a curved compact tension specimen (CCTS) and a pressure tube burst specimen (PT) with axial through-wall crack used in destructive burst test were studied in details. The intention was to identify any differences between fracture behavior of the CCTS and the PT potentially affecting fracture toughness estimates. The stress and deformation states ahead of the crack front, calculated fracture toughness parameters including J-integral and crack tip opening displacement (CTOD), as well as fracture constraint by means of elastic T-stress have been discussed.

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