scholarly journals Crack Tip Field of a Double-Network Gel: Visualization of Covalent Bond Scission through Mechanoradical Polymerization

2020 ◽  
Vol 53 (20) ◽  
pp. 8787-8795
Author(s):  
Takahiro Matsuda ◽  
Runa Kawakami ◽  
Tasuku Nakajima ◽  
Jian Ping Gong
Keyword(s):  
Crack Tip ◽  
Covalent Bond ◽  
Crack Tip Field ◽  
Double Network ◽  
Bond Scission

scholarly journals Crack Tip Field of a Double-Network Gel: Visualizing Covalent Bond Scission by Mechanoradical Polymerization

2020 ◽  
Author(s):  
Takahiro Matsuda ◽  
Runa Kawakami ◽  
Tasuku Nakajima ◽  
Jian Ping Gong
Keyword(s):  
Fracture Energy ◽  
Damage Zone ◽  
Crack Tip ◽  
Covalent Bond ◽  
Soft Materials ◽  
Chain Scission ◽  
Thermoresponsive Polymer ◽  
Crack Tip Field ◽  
Double Network ◽  
Bond Scission

Quantitative characterization of the energy dissipative zone around the crack tip is the central issue in fracture mechanics of soft materials. In this research, we present a mechanochemical technique to visualize the bond scission of the first network in the damage zone of tough double-network hydrogels. The mechanoradicals generated by polymer chain scission are employed to initiate polymerization of a thermoresponsive polymer, which is visualized by a fluorophore. This technique records the spatial distribution of internal fracturing from the fractured surface to the bulk, which provides the spatial profiles of stress, strain, and energy dissipation around the crack-tip. The characterized results suggest that, in addition to the dissipation in relatively narrow yielded zone which is mostly focused in the previous works, the dissipation in wide pre-yielding zone and the intrinsic fracture energy have also significant contribution to the fracture energy of a DN gel.

scholarly journals Crack Tip Field of a Double-Network Gel: Visualizing Covalent Bond Scission by Mechanoradical Polymerization

2020 ◽  
Author(s):  
Takahiro Matsuda ◽  
Runa Kawakami ◽  
Tasuku Nakajima ◽  
Jian Ping Gong
Keyword(s):  
Fracture Energy ◽  
Damage Zone ◽  
Crack Tip ◽  
Covalent Bond ◽  
Soft Materials ◽  
Chain Scission ◽  
Thermoresponsive Polymer ◽  
Crack Tip Field ◽  
Double Network ◽  
Bond Scission

Quantitative characterization of the energy dissipative zone around the crack tip is the central issue in fracture mechanics of soft materials. In this research, we present a mechanochemical technique to visualize the bond scission of the first network in the damage zone of tough double-network hydrogels. The mechanoradicals generated by polymer chain scission are employed to initiate polymerization of a thermoresponsive polymer, which is visualized by a fluorophore. This technique records the spatial distribution of internal fracturing from the fractured surface to the bulk, which provides the spatial profiles of stress, strain, and energy dissipation around the crack-tip. The characterized results suggest that, in addition to the dissipation in relatively narrow yielded zone which is mostly focused in the previous works, the dissipation in wide pre-yielding zone and the intrinsic fracture energy have also significant contribution to the fracture energy of a DN gel.

Mismatch Effect on the Mixed Mode Type Creep Crack within Weldment

2016 ◽  
Vol 853 ◽  
pp. 281-285
Author(s):  
Jun Hui Zhang ◽  
Yan Wei Dai
Keyword(s):  
Mixed Mode ◽  
Stress Triaxiality ◽  
Crack Tip ◽  
Crack Tip Field ◽  
Creep Crack ◽  
Loading Mode ◽  
The Difference ◽  
Engineering Practices ◽  
Mismatch Effect ◽  
Transient And Steady State

Creep crack within weldments are very common in engineering practices, and the cracking location in these welding structures always appears at the HAZ location. The mismatch effect on the mixed mode creep crack is still not clear in these available literatures. The aim of this paper is to investigate the mismatch influence on the creep crack of mixed mode thoroughly. A mixed mode creep crack within HAZ is established in this paper. The leading factor that dominates the creep crack tip field under mixed loading mode is studied. The influences of mismatch effect on mode mixity, stress distribution and stress triaxiality are proposed. The difference of mixed mode creep crack and normal mode I or mode II creep crack are compared. The influence of mixity factor on the transient and steady state creep of crack tip are also analyzed.

scholarly journals Multicolor Mechanofluorophores for the Quantitative Detection of Covalent Bond Scission in Polymers

2021 ◽  
Author(s):  
Christoph Baumann ◽  
Maria Stratigaki ◽  
Silvia P. Centeno ◽  
Robert Göstl
Keyword(s):  
Covalent Bond ◽  
Quantitative Detection ◽  
Bond Scission

INVESTIGATIONS ON THE DYNAMIC NEAR-CRACK-TIP FIELD USING THE GRID METHOD

1988 ◽  
Vol 49 (C3) ◽  
pp. C3-307-C3-312
Author(s):  
K. KUSSMAUL ◽  
T. DEMLER ◽  
A. KLENK
Keyword(s):  
Crack Tip ◽  
Grid Method ◽  
Crack Tip Field

Modeling Dislocation-Mediated Hydrogen Transport and Trapping in Fcc Metals

2021 ◽  
pp. 1-54
Author(s):  
Theodore Zirkle ◽  
Luke Costello ◽  
Ting Zhu ◽  
David L. McDowell
Keyword(s):  
Transport Model ◽  
Constitutive Relations ◽  
Crack Tip ◽  
Lattice Diffusion ◽  
Hydrogen Transport ◽  
Crack Tip Field ◽  
Coupled Diffusion ◽  
Crystal Plasticity Model ◽  
Physically Based ◽  
Material Ductility

Abstract The diffusion of hydrogen in metals is of interest due to the deleterious influence of hydrogen on material ductility and fracture resistance. It is becoming increasingly clear that hydrogen transport couples significantly with dislocation activity. In this work, we employ a coupled diffusion-crystal plasticity model to incorporate hydrogen transport associated with dislocation sweeping and pipe diffusion in addition to standard lattice diffusion. Moreover, we consider generation of vacancies via plastic deformation and stabilization of vacancies via trapping of hydrogen. The proposed hydrogen transport model is implemented in a physically-based crystal viscoplasticity framework to model the interaction of dislocation substructure and hydrogen migration. In this study, focus is placed on hydrogen transport and trapping within the intense deformation field of a crack tip plastic zone. We discuss the implications of the model results in terms of constitutive relations that incorporate hydrogen effects on crack tip field behavior and enable exploration of hydrogen embrittlement mechanisms.

scholarly journals Mixed-mode crack tip fields in a polycrystalline aluminum alloy

2019 ◽  
Vol 300 ◽  
pp. 11004 ◽  
Author(s):  
Marcel Wicke ◽  
Angelika Brueckner-Foit
Keyword(s):  
Mixed Mode ◽  
Crack Tip ◽  
Strain Partitioning ◽  
Crack Tip Field ◽  
Polycrystalline Aluminum ◽  
Digital Twin ◽  
Crack Tip Fields ◽  
Mixed Mode Crack ◽  
Threshold Regime ◽  
Near Threshold

Carefully performed experiments with long cracks in the near-threshold regime have shown that the crack tip field of these cracks significantly deviate from the expected mode-I butterfly-shaped ones and resemble strongly to mixed-mode crack tip fields. A simulation study using a crystal plasticity (CP) approach has been utilized in order to understand this phenomenon. To this end, a digital twin of an aluminum sample fatigued in the near-threshold regime was generated with the help of electron backscatter diffraction (EBSD) and X-ray tomography. Once set-up, the digital twin was loaded in uniaxial tension using the fast spectral solver implemented in the Düsseldorf Advanced Material Simulation Kit (DAMASK). The versatility of this experimental-computational approach for studying the strain partitioning at the crack tip is demonstrated in this work.

Higher-Order Terms for the Mode-III Stationary Crack-Tip Fields in a Functionally Graded Material

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
Linhui Zhang ◽  
Jeong-Ho Kim
Keyword(s):  
Functionally Graded Material ◽  
Crack Tip ◽  
Functionally Graded ◽  
Mode Iii ◽  
Stationary Crack ◽  
Crack Tip Field ◽  
Homogeneous Solutions ◽  
Variable Approach ◽  
Graded Material ◽  
Plane Displacement

This paper provides full asymptotic crack-tip field solutions for an antiplane (mode-III) stationary crack in a functionally graded material. We use the complex variable approach and an asymptotic scaling factor to provide an efficient procedure for solving standard and perturbed Laplace equations associated with antiplane fracture in a graded material. We present the out-of-plane displacement and the shear stress solutions for a crack in exponentially and linearly graded materials by considering the gradation of the shear modulus either parallel or perpendicular to the crack. We discuss the characteristics of the asymptotic solutions for a graded material in comparison with the homogeneous solutions. We address the effects of the mode-III stress intensity factor and the antiplane T-stress onto crack-tip field solutions. Finally, engineering significance of the present work is discussed.

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