Determination of Fracture Toughness for Metal/Polymer Interfaces

1999 ◽  
Vol 121 (4) ◽  
pp. 275-281 ◽  
Author(s):  
V. Sundararaman ◽  
S. K. Sitaraman
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Release Rate ◽  
Critical Energy ◽  
Material Behavior ◽  
Finite Element Analyses ◽  
Critical Energy Release Rate ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Metal Polymer

This work focuses on the interpretation of experimental results obtained from fracture toughness tests conducted for a typical metal/polymer bimaterial interface similar to those encountered in electronic packaging applications. Test specimens with pre-implanted interfacial cracks were subjected to a series of fracture toughness tests. Interfacial fracture toughness is interpreted from the experimental results as the critical energy release rate (Gc) at the instant of crack advance. The values of Gc from the experiments are determined using direct data reduction methods assuming linear elastic material behavior. These Gc values are compared to critical energy release rate values predicted by closed-from analyses of the tests, and to critical J-integral values obtained from finite-element analyses of the test specimen geometries. The closed-form analyses assume linear elastic material behavior, while the finite-element analyses assume both linear elastic as well as elastic-plastic material behaviors.

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.

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.

Determination of Energy Release Rate Through Sequential Crack Extension

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Scott McCann ◽  
Gregory T. Ostrowicki ◽  
Anh Tran ◽  
Timothy Huang ◽  
Tobias Bernhard ◽  
...  
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Critical Energy ◽  
External Work ◽  
Critical Energy Release Rate ◽  
Conservation Of Energy

A method to determine the critical energy release rate of a peel tested sample using an energy-based approach within a finite element framework is developed. The method uses a single finite element model, in which the external work, elastic strain energy, and inelastic strain energy are calculated as nodes along the crack interface are sequentially decoupled. The energy release rate is calculated from the conservation of energy. By using a direct, energy-based approach, the method can account for large plastic strains and unloading, both of which are common in peel tests. The energy rates are found to be mesh dependent; mesh and convergence strategies are developed to determine the critical energy release rate. An example of the model is given in which the critical energy release rate of a 10-μm thick electroplated copper thin film bonded to a borosilicate glass substrate which exhibited a 3.0 N/cm average peel force was determined to be 20.9 J/m2.

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).

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.

Fracture Toughness of Nanomodified-Epoxy Systems

2013 ◽  
Vol 393 ◽  
pp. 206-211 ◽  
Author(s):  
Aidah Jumahat ◽  
Constantinos Soutis ◽  
Ahmad Nurulnatisya ◽  
Wan Mazlina Wan Mohamed
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Release Rate ◽  
Critical Stress ◽  
Critical Energy ◽  
Critical Stress Intensity Factor ◽  
Critical Energy Release Rate

The effect of nanosilica, multiwalled carbon nanotubes (MWCNT) and montmorillonite (MMT) nanoclay on critical stress intensity factor and critical energy release rate of Epikote 828 epoxy polymer was studied. Fracture toughness tests were conducted on three types of nanocomposites which contain 5-25 wt% nanosilica, 0.5-1 wt% MWCNT and 1-5 wt% MMT nanoclay. The compact tension specimens of 9 mm initial crack length were fabricated and tested in tension. It was found that, the load at crack growth initiation FQfor all nanomodified polymer systems was higher than that of the neat epoxy. Hence, the presence of nanosilica, carbon nanotubes and nanoclay improves the critical stress intensity factor and critical energy release rate of the polymer. For the nanoclay-modified epoxy system, the degree of enhancement depends on the morphology of the nanocomposites. At high nanoclay content (> 3 wt%), a detrimental effect on the fracture toughness was observed. This is due to a weak nanomer/epoxy interfaces in a highly intercalated structure nanocomposite.

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.

Linear translaminar fracture characterization of additive manufactured continuous carbon fiber reinforced thermoplastic

2021 ◽  
pp. 089270572110214
Author(s):  
Weiller M Lamin ◽  
Flávio LS Bussamra ◽  
Rafael TL Ferreira ◽  
Rita CM Sales ◽  
José E Baldo
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Fracture Mechanics ◽  
Image Correlation ◽  
Fiber Reinforced ◽  
Fused Filament Fabrication ◽  
Critical Energy Release Rate ◽  
Linear Elastic ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

This work presents the experimental determination of fracture mechanics parameters of composite specimens manufactured by fused filament fabrication (FFF) with continuous carbon fiber reinforced thermoplastic filaments, based on Linear Elastic Fracture Mechanics (LEFM). The critical mode I translaminar fracture toughness (KIc) and the critical energy release rate (GIc) are found for unidirectional and cross-ply laminates. The specimens were submitted to quasi-static tensile testing. Digital Image Correlation (DIC) is used to find the stress field. The stress fields around the crack tip are compared to linear elastic finite element simulations. The results demonstrate the magnitude of fracture toughness is in the same range as for polymers and some metals, depending on lay-up configuration. Besides, fractographic analyses show some typical features as river lines, fiber impression, fiber pulls-out and porosity aspects.

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