scholarly journals Role of ionic interactions in the deformation and fracture behavior of perfluorosulfonic-acid membranes

Soft Matter ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1653-1667 ◽  
Author(s):  
Shouwen Shi ◽  
Zheng Liu ◽  
Qiang Lin ◽  
Xu Chen ◽  
Ahmet Kusoglu
Keyword(s):  
Fracture Toughness ◽  
Strain Hardening ◽  
Fracture Behavior ◽  
Deformation Mechanisms ◽  
Ionic Interactions ◽  
Perfluorosulfonic Acid ◽  
Deformation And Fracture ◽  
Perfluorosulfonic Acid Membranes

Modulus, strain-hardening and fracture toughness of cation-exchanged PFSAs are interrelated via deformation mechanisms influenced by the ionic interactions governing relationships between strength vs. toughness, and stretchability vs. stiffness.

A magnetic resonance and electrochemical study of the role of polymer mobility in supporting hydrogen transport in perfluorosulfonic acid membranes

2018 ◽  
Vol 20 (28) ◽  
pp. 19098-19109 ◽  
Author(s):  
Z. Blossom Yan ◽  
Alan P. Young ◽  
Gillian R. Goward
Keyword(s):  
Magnetic Resonance ◽  
Polymer Electrolyte Membrane ◽  
Hydrogen Transport ◽  
High Proton Conductivity ◽  
Perfluorosulfonic Acid ◽  
Electrolyte Membrane ◽  
High Proton ◽  
Perfluorosulfonic Acid Membranes ◽  
Mechanical Durability

Perfluorosulfonic acid (PFSA) materials have been used in polymer electrolyte membrane fuel cells (PEMFCs) as electrolyte materials due to their mechanical durability and high proton conductivity.

Role of Process and Microstructural Parameters on Mixed Mode Fracture of Sn-Ag-Cu Solder Joints Under Dynamic Loading Conditions

2009 ◽  
Author(s):  
P. Kumar ◽  
Z. Huang ◽  
I. Dutta ◽  
R. Mahajan ◽  
M. Renavikar ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Solder Joints ◽  
Mixed Mode Fracture ◽  
Strain Rates ◽  
Solder Microstructure ◽  
Dynamic Loading Conditions ◽  
Crack Profile

Electronic packages in mobile devices are often subjected to drops, leading to impact loading. Since solder joints, which serve as mechanical and electrical interconnects in a package, are particularly prone to failure during a drop, the fracture behavior of solders at high strain rates is a critical design parameter for building robust packages. Here we report on a methodology for measuring mixed-mode fracture toughness of Sn3.5Ag0.7Ag (SAC387) solder joints under dynamic loading conditions (at strain rates up to 100s−1), and use this method to investigate the role of solder microstructure and interfacial intermetallic compound (IMC) layer thickness on the joint fracture toughness at different mode-mixities and strain rates. Modified compact mixed mode (CMM) samples with adhesive solder joints between Cu plates and a thin film interfacial starter crack were used for the measurements. The interfacial IMC layer thickness was adjusted by controlling the dwell time during reflow, while the solder microstructure was controlled via the post-reflow cooling rate and subsequent thermal aging. The critical strain energy release rate (Gc) was measured as a function of these microstructural and loading variables, and these data were correlated with the associated crack path, details of which were elicited through fractography as well as crack-profile observations. The crack profile studies were based on samples with double interfacial starter cracks, one of which propagated only partially. Associated with the alteration of the joint microstructure, transitions in the fracture behavior were noted. In all cases, the cracks remained confined to the interfacial region, although the details of the crack propagation path and its interaction with interfacial IMCs, the adjacent solder and the pad surface finish varied significantly. Fracture toughness decreased with an increase in the strain rate and decreased with increasing mode-mixity. A thicker/coarser interfacial IMC layer (due to high dwell times) decreased toughness, while coarser solder microstructures (due to slow cooling during reflow or post-reflow aging) increased toughness. Correlations between joint microstructure and the observed deformation and fracture mechanisms will be highlighted, and a qualitative model based explanation for the inter-play between solder and IMC, and the associated interfaces will be presented.

Fracture Toughness of Whisker Reinforced Ceramics

2010 ◽  
Vol 430 ◽  
pp. 41-46
Author(s):  
Makoto Katagiri ◽  
Akihiko Kumaki ◽  
Yoshito Izumi ◽  
H. Suzuki ◽  
Hideki Sekine
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Simulation Method ◽  
Cohesive Stress ◽  
Numerical Simulation Method ◽  
Deformation And Fracture ◽  
Tension Softening ◽  
Alumina Composite

By use of a probabilistic fracture model, a numerical simulation method for deformation and fracture behavior of whisker reinforced ceramics is developed first. A crack in whisker reinforced ceramics is regarded as the crack with a cohesive stress acting on the crack surface, and then the tension-softening relation is derived on the basis of a micromechanical study. After the numerical simulation method is constructed by incorporating the tension-softening relation in an FEM scheme, we simulate the load-load point displacement relationship for an edge-cracked bend specimen of a SiC whisker/alumina composite. The fracture toughness determined from the simulated maximum load is consistent with that obtained from experiment.

Deformation twinning in superlattice structures

1989 ◽  
Vol 4 (1) ◽  
pp. 50-54 ◽  
Author(s):  
M. H. Yoo
Keyword(s):  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Ordered Structures ◽  
Deformation And Fracture ◽  
Ordered Alloys ◽  
Ordered Intermetallic ◽  
Superlattice Structures ◽  
Strength And Ductility ◽  
Active Slip

The role of twinning in deformation and fracture behavior of ordered intermetallic compounds has been investigated from a viewpoint based on the crystallography of twinning. The conjugate relationship between the order twinning and the active slip system at elevated temperatures is identified in all the ordered structures considered. Implications of this conjugate relationship on the strength and ductility of ordered alloys are discussed.

The Role of Grain Size in Predicting Cleavage Fracture Toughness of Pressure Vessel Steels

2013 ◽  
Author(s):  
Marjorie Erickson ◽  
Kristine B. Cochran ◽  
B. Richard Bass ◽  
Paul T. Williams
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Fracture Mode ◽  
Fracture Behavior ◽  
National Laboratory ◽  
Scale Model ◽  
Mode Transition ◽  
Oak Ridge ◽  
Microcrack Initiation

A theoretical, multi-scale model has been developed to predict the fracture toughness of ferritic steels in the ductile-to-brittle fracture mode transition temperature region. The new model is being implemented into the DISlocation-based FRACture (DISFRAC) computer code at the Oak Ridge National Laboratory (ORNL) and will permit fracture safety assessments of ferritic structures with only tensile properties and microstructural information (grain and carbide size) required as input. The theoretical basis of this model provides a means of predicting fracture behavior outside of the ranges of data currently used in deriving empirically-based models and should provide a means of improving the understanding of fracture behavior in the fracture mode transition region. Dislocation distribution equations, derived from dislocation theory developed by Yokobori et al., are combined with modified boundary layer solutions to account for the stress state local to various microstructural features believed to control fracture behavior. Terms are included to account for microcrack initiation in brittle grain boundary particles, propagation of the microcrack into the first ferrite grain and then through subsequent grain boundaries accounting for local tilt and twist grain misorientation across boundaries. This paper summarizes the DISFRAC model and provides the results of a study performed to investigate the role of grain size in microcrack initiation, propagation and the resulting prediction of fracture toughness.

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