scholarly journals Interfacial Fracture Toughness Measurement of Welded Babbitt alloy SnSb11Cu6/ 20Steel

2021 ◽  
Author(s):  
Yuepeng Gao ◽  
Janmei Wang ◽  
Yuyang Liu
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Phase Angle ◽  
Release Rate ◽  
Critical Energy ◽  
Critical Energy Release Rate ◽  
Stress Phase Angle ◽  
Babbitt Alloy

The interface fracture toughness of SnSb11Cu6/20steel was measured by calculating the critical energy release rate and stress phase angle of the interface crack. A three-point bending test was used to introduce cracks into the bonding interface, and the cohesion model of the bonding interface was established through experimental data. Through finite element analysis of load-deflection curves with and without interface crack propagation, the crack initiation point is found. Then the energy calculation model of crack propagation is established, and the critical energy release rate is obtained using the virtual crack growth criterion. The calculation results of the stress phase angle show that the crack propagation is greatly affected by the normal stress after the babbitt alloy layer fractures. If the strength of the substrate material is weaker, the crack will continue to expand in the tangent perpendicular to the crack tip.

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 Mode II fracture behavior of parallel strand bamboo measured by 3-point end-notched flexure tests

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3219-3227
Author(s):  
Zhen-wen Zhang ◽  
Jia-liang Zhang ◽  
Yu-shun Li ◽  
Riu Liu
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Fracture Process ◽  
Fracture Behavior ◽  
Critical Energy ◽  
Mode Ii ◽  
Critical Energy Release Rate ◽  
Propagation Length

Parallel strand bamboo (PSB) is a new type of bio-composite. In the present study, three-point bend end-notched flexure (3ENF) tests of PSB were conducted to analyze the fracture behavior including fracture process, resistant curves, and critical energy release rate in the longitudinal (L) system. The results show that transverse-longitudinal (TL) and thickness-longitudinal (ZL) specimens had the same fracture process including the stages of fracture process zone (FPZ) development and opening crack propagation but different mode II critical energy release rate (GIIc), and they indicate that the fiber bridging had a significant influence. The fracture processes suggest the PSB specimens of which the initial crack length was 0.5 times the half span had a stable crack propagating process, and the crack propagation length was wide enough to evaluate GIIc, which was 5.02 N∙mm-1 of TL specimens and 2.71 N∙mm-1 of ZL specimens. Besides, there was no obvious influence of span/depth ratio on the fracture resistance of both ZL and TL specimens when the ratio was larger than 15.

Crack Propagation Modeling in a PWR Under PTS Using XFEM

2020 ◽  
Author(s):  
Diego F. Mora ◽  
Markus Niffenegger ◽  
Roman Mukin
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Evolution ◽  
Evolution Model ◽  
Critical Energy Release Rate ◽  
Damage Initiation

Abstract The finite element simulation of fracture propagation of BCC metals is challenging, as it needs to incorporate the brittle, ductile-brittle transition and ductile behavior presented by the fracture toughness. In this contribution, we restrict ourselves to the use of XFEM method to simulate the cleavage fracture due to initial flaws in the reactor pressure vessel of a reference design of the two-loop PWR nuclear power plant. A hypothetical large break loss of coolant accident is selected as accident scenario to obtain the loading conditions under which the crack is subjected. The thermal-mechanical calculation is performed using a finite element model of the whole RPV and the initial and boundary conditions are determined from the thermal-hydraulic simulation of the transient in TRACE. The method proposed in this contribution is based on the cohesive segment approach implemented in ABAQUS, which requires the definition of the damage properties of the material. The segment approach does not use the fracture toughness as failure criterion. Instead, it uses a traction separation law that is able to capture the brittle fracture behavior of ferritic steel. The crack propagation in XFEM uses a propagation criterion based on a cohesive damage initiation criterion and a damage evolution model. In order to implement the damage evolution model, the fracture energy release rate is directly related to the fracture toughness. The postulated crack is inserted in a submodel to reduce the computational cost of the calculation. The location of such submodel corresponds to the region of the core that suffers maximum irradiation and is subjected to high tensile stresses due to the cooling plume generated during the transient PTS cooling. The crack propagation analysis of postulated axial crack showed that its propagation happens in axial direction in those finite elements close to the inner surface because the energy release rate GI is larger than the critical energy release rate GIC. At the deepest point of the crack, the stresses in the finite element fulfil the damage initiation criterion but the crack does not propagate in radial direction (GI < GIC).

An Analytic Solution for Characterizing the Fracture Toughness of the Inhomogenous Coatings on Substrates

2011 ◽  
Vol 480-481 ◽  
pp. 662-667
Author(s):  
Ban Quan Yang ◽  
Fa Xin Li
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Analytic Solution ◽  
Critical Energy ◽  
Analytic Solutions ◽  
Beam Model ◽  
Critical Energy Release Rate ◽  
Strength Gradient

A mechanical model of coating-substrate specimen is developed that allows us to derive analytical solution to quantify the residual stress and yield strength gradient effect resulting from surface heat treatment on energy release rate of the coating on its substrate. Using a Micro-Composite-Double-Cantilever–Beam Model (MCDCBM), the analytic solutions can be derived, and they can be used to characterize the fracture toughness of the inhomogenous coatings on substrates in terms of the critical energy release rate. Finally, a numerical example is presented to show how the critical energy release rate is obtained.

scholarly journals Study of Strain-Hardening Behaviour of Fibre-Reinforced Alkali-Activated Fly Ash Cement

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4015
Author(s):  
Hyuk Lee ◽  
Vanissorn Vimonsatit ◽  
Priyan Mendis ◽  
Ayman Nassif
Keyword(s):  
Fly Ash ◽  
Energy Release Rate ◽  
Strain Hardening ◽  
Energy Release ◽  
Release Rate ◽  
Critical Energy ◽  
Critical Energy Release Rate ◽  
Pull Out ◽  
Alkali Activated ◽  
Alkali Activated Cement

This paper presents a study of parameters affecting the fibre pull out capacity and strain-hardening behaviour of fibre-reinforced alkali-activated cement composite (AAC). Fly ash is a common aluminosilicate source in AAC and was used in this study to create fly ash based AAC. Based on a numerical study using Taguchi’s design of experiment (DOE) approach, the effect of parameters on the fibre pull out capacity was identified. The fibre pull out force between the AAC matrix and the fibre depends greatly on the fibre diameter and embedded length. The fibre pull out test was conducted on alkali-activated cement with a capacity in a range of 0.8 to 1.0 MPa. The strain-hardening behaviour of alkali-activated cement was determined based on its compressive and flexural strengths. While achieving the strain-hardening behaviour of the AAC composite, the compressive strength decreases, and fine materials in the composite contribute to decreasing in the flexural strength and strain capacity. The composite critical energy release rate in AAC matrix was determined to be approximately 0.01 kJ/m 2 based on a nanoindentation approach. The results of the flexural performance indicate that the critical energy release rate of alkali-activated cement matrix should be less than 0.01 kJ/m 2 to achieve the strain-hardening behaviour.

scholarly journals INTERFACE FRACTURE TOUGHNESS ASSESSMENT OF SOLDER JOINTS USING DOUBLE CANTILEVER BEAM TEST

2010 ◽  
Vol 24 (01n02) ◽  
pp. 164-174 ◽  
Author(s):  
SHANE ZHI YUAN LOO ◽  
PUAY CHENG LEE ◽  
ZAN XUAN LIM ◽  
NATALIA YANTARA ◽  
TONG YAN TEE ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Solder Joint ◽  
Energy Release Rate ◽  
Release Rate ◽  
Double Cantilever Beam ◽  
Interface Reaction ◽  
Critical Energy ◽  
Interface Fracture ◽  
Critical Energy Release Rate ◽  
Interface Fracture Toughness

In the current work, a test scheme to evaluate solder joint interface fracture toughness using double cantilever beam (DCB) test has been successfully demonstrated. The obtained results, in terms of critical energy release rate, predict the joint failure based on the principle of fracture mechanics. The results can be used as a materials property in the reliability design of various types of solder-ball joined packages. DCB specimens made of 99.9 wt% copper were selected in the current work. Eutectic Sn -37 Pb and lead-free Sn -3.5 Ag -0.5 Cu solders were used to join two pieces of the copper beams with controlled solder thickness. The test record showed steady propagation of the crack along the solder / copper interface, which verifies the viability of such a testing scheme. Interface fracture toughness for as-joined, extensively-reflowed and thermally aged samples has been measured. Both the reflow treatment and the thermal aging lead to degradation of the solder joint fracture resistance. Reflow treatment was more damaging as it induces much faster interface reaction. Fractographic analysis established that the fracture has a mixed micromechanism of dimple and cleavage. The dimples are formed as a result of the separation between the hard intermetallic compound (IMC) particles and the soft solder material, while the cleavage is formed by the brittle split of the IMCs. When the IMC thickness is increased due to extended interface reaction, the proportion of IMC cleavage failure increases, and this was reflected in the decrease of the critical energy release rate.

Effect of Characteristic Parameters of Exponential Cohesive Zone Model on Mode I Fracture of Laminated Composites

2012 ◽  
Vol 525-526 ◽  
pp. 409-412 ◽  
Author(s):  
Guo Wei Zhu ◽  
Yu Xi Jia ◽  
Peng Qu ◽  
Jia Qi Nie ◽  
Yun Li Guo
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Laminated Composites ◽  
Peak Load ◽  
Interfacial Strength ◽  
Critical Energy ◽  
Mode I ◽  
Zone Model ◽  
Critical Energy Release Rate

Delamination is a particularly dangerous damage mode of high performance laminated composites. In order to describe the composites ductile cracking and its progressive evolution accurately, the adjusted exponential cohesive zone model (CZM) is adopted, which correlates the tensile traction with the corresponding interfacial separation along the fracturing interfacial zone. At first the adjusted exponential CZM is used to simulate the mode I delamination of the standard double cantilever beam (DCB). The simulated results are in good agreement with the corrected beam theory and the corresponding experimental results. Then in order to research how the interfacial properties influence the mode I fracture, the interfacial strength and the critical energy release rate are studied. The main results are obtained as follows. The interfacial strength plays a crucial role in the laminated composites delamination onset, and it affects the peak load significantly if there is not a pre-crack. Once the delamination propagation begins to occur in the laminated composites, the responses of the load-displacement plots are relatively insensitive to the interfacial strength, and only the critical energy release rate is of critical importance. Furthermore, the peak load increases with the increase of the critical energy release rate and interfacial strength.

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