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.

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

The Tip Field of Mode III Crack in Damage Material

2011 ◽  
Vol 236-238 ◽  
pp. 2790-2793
Author(s):  
Xiu Hong Wang ◽  
Bo Liu ◽  
Li Qiang Tang
Keyword(s):  
Constitutive Equation ◽  
Damage Zone ◽  
Crack Tip ◽  
Damage Threshold ◽  
Threshold Value ◽  
Complex Problem ◽  
Mode Iii ◽  
Crack Tip Field ◽  
Stress Strain ◽  
Initial Damage

The research of crack-tip field in damage materials is a very complex problem. The core question is how to give the damage constitutive equation and determine the crack tip singularity order of magnitude of the physical quantities. Taking into account the damage process is a process which the energy (strain) accumulates, and the initial damage threshold value existence, on the Lemaitre’s research foundation, the brittle material damage constitutive equation that has the initial damage quantity and the power order relationship with strain is given. Under the assumption that stress (strain) is finite, the construction of III mode crack tip damage fields is studied and the solution of crack-tip stress (strain) asymptotic field is given. Finally, the relationship of the initial crack tip damage zone and full damage zone Scale and material parameters are discusses. These works provide theoretical basis for the material engineering design and the appraisal structure reliability.

Experimental Analysis of the Damage Zone around Crack Tip for Rubberlike Materials under Mode-I Fracture Condition

2013 ◽  
Vol 561 ◽  
pp. 119-124 ◽  
Author(s):  
Xiao Lei Li ◽  
Xiao Jing Li ◽  
Jian Bing Sang ◽  
Yan Hui Qie ◽  
Yao Ping Tu ◽  
...  
Keyword(s):  
Damage Zone ◽  
Crack Tip ◽  
Soft Materials ◽  
Mode I ◽  
Mode I Fracture ◽  
Crack Tip Fields ◽  
Fracture Condition ◽  
Deformation And Fracture ◽  
Digital Moiré ◽  
Rubberlike Materials

Studying the deformation and fracture properties of soft materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of rubberlike materials. In this paper, an application of the experimental digital moire method to determine the damage zone around crack tip for rubberlike material is presented. The measurement principles and the basic procedures of the method are explained in detail. The in-plane defomation distributions of crack tip fields under Mode I fracture condition are measured. In addition, the deformation of crack tip fields in the damage zones is also analyzed using the sector division mode. Finally, an analysis of the damage zone is proposed to describe crack-tip fields in rubber-like materials with large deformation.

scholarly journals Why is Mechanical Fatigue Different from Toughness in Elastomers? The Role of Damage by Polymer Chain Scission

2021 ◽  
Author(s):  
Gabriel Sanoja ◽  
Xavier P. Morelle ◽  
Jean Comtet ◽  
C. Joshua Yeh ◽  
Matteo Ciccotti ◽  
...  
Keyword(s):  
Applied Load ◽  
Areal Density ◽  
Chain Scission ◽  
Fracture Mechanisms ◽  
Environmental Footprint ◽  
Double Network ◽  
Mechanical Fatigue ◽  
Bond Scission ◽  
Mechanical Durability

<p>Although elastomers often experience 10-100 million cycles prior to failure, there is currently a limited understanding of their resistance to fatigue crack propagation. We use soft and tough double-network elastomers tagged with mechanofluorescent probes to understand the role of damage by sacrificial bond scission on their mechanical durability and fracture toughness. Damage accumulation and localization ahead of the crack tip depend on the areal density of sacrificial bonds, as well as on the applied load (<i>i.e.</i>, cyclic or monotonic). This information serves to engineer fatigue resistant elastomers, understand fracture mechanisms, and reduce the environmental footprint of the polymer industry.</p>

Experimental Analysis of the Damage Zone around Crack Tip for Rubberlike Materials under Mode-I Fracture Condition

2013 ◽  
Vol 341-342 ◽  
pp. 283-286
Author(s):  
Xiao Lei Li ◽  
Xiao Jing Li ◽  
Jian Bing Sang ◽  
Yan Hui Qie ◽  
Yao Ping Tu ◽  
...  
Keyword(s):  
Damage Zone ◽  
Crack Tip ◽  
Soft Materials ◽  
Physical Mechanisms ◽  
Crack Tip Fields ◽  
Deformation And Fracture ◽  
Rubberlike Material ◽  
Moire Method ◽  
Digital Moiré ◽  
Rubberlike Materials

Studying the deformation and fracture properties of soft materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of rubberlike materials. In this paper, an application of the experimental digital moire method to determine the damage zone around crack tip for rubberlike material is presented. The measurement principles and the basic procedures of the method are explained in detail. The deformation of crack tip fields in the damage zones is analyzed using the sector division mode. Finally, an analysis of the damage zone is proposed to describe crack-tip fields in rubber-like materials with large deformation.

scholarly journals Why is Mechanical Fatigue Different from Toughness in Elastomers? The Role of Damage by Polymer Chain Scission

2021 ◽  
Author(s):  
Gabriel Sanoja ◽  
Xavier P. Morelle ◽  
Jean Comtet ◽  
C. Joshua Yeh ◽  
Matteo Ciccotti ◽  
...  
Keyword(s):  
Applied Load ◽  
Areal Density ◽  
Chain Scission ◽  
Fracture Mechanisms ◽  
Environmental Footprint ◽  
Double Network ◽  
Mechanical Fatigue ◽  
Bond Scission ◽  
Mechanical Durability

<p>Although elastomers often experience 10-100 million cycles prior to failure, there is currently a limited understanding of their resistance to fatigue crack propagation. We use soft and tough double-network elastomers tagged with mechanofluorescent probes to understand the role of damage by sacrificial bond scission on their mechanical durability and fracture toughness. Damage accumulation and localization ahead of the crack tip depend on the areal density of sacrificial bonds, as well as on the applied load (<i>i.e.</i>, cyclic or monotonic). This information serves to engineer fatigue resistant elastomers, understand fracture mechanisms, and reduce the environmental footprint of the polymer industry.</p>

How chain dynamics affects crack initiation in double-network gels

2021 ◽  
Vol 118 (49) ◽  
pp. e2111880118
Author(s):  
Yong Zheng ◽  
Takahiro Matsuda ◽  
Tasuku Nakajima ◽  
Wei Cui ◽  
Ye Zhang ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Damage Zone ◽  
Soft Materials ◽  
Polymer Dynamics ◽  
Internal Damage ◽  
Double Network ◽  
Solvent Viscosity ◽  
Elastic Networks ◽  
Unique Material

Double-network gels are a class of tough soft materials comprising two elastic networks with contrasting structures. The formation of a large internal damage zone ahead of the crack tip by the rupturing of the brittle network accounts for the large crack resistance of the materials. Understanding what determines the damage zone is the central question of the fracture mechanics of double-network gels. In this work, we found that at the onset of crack propagation, the size of necking zone, in which the brittle network breaks into fragments and the stretchable network is highly stretched, distinctly decreases with the increase of the solvent viscosity, resulting in a reduction in the fracture toughness of the material. This is in sharp contrast to the tensile behavior of the material that does not change with the solvent viscosity. This result suggests that the dynamics of stretchable network strands, triggered by the rupture of the brittle network, plays a role. To account for this solvent viscosity effect on the crack initiation, a delayed blunting mechanism regarding the polymer dynamics effect is proposed. The discovery on the role of the polymer dynamic adds an important missing piece to the fracture mechanism of this unique material.

scholarly journals Why is Mechanical Fatigue Different from Toughness in Elastomers? The Role of Damage by Polymer Chain Scission

2021 ◽  
Author(s):  
Gabriel Sanoja ◽  
Xavier P. Morelle ◽  
Jean Comtet ◽  
C. Joshua Yeh ◽  
Matteo Ciccotti ◽  
...  
Keyword(s):  
Applied Load ◽  
Areal Density ◽  
Chain Scission ◽  
Fracture Mechanisms ◽  
Environmental Footprint ◽  
Double Network ◽  
Mechanical Fatigue ◽  
Bond Scission ◽  
Mechanical Durability

<p>Although elastomers often experience 10-100 million cycles prior to failure, there is currently a limited understanding of their resistance to fatigue crack propagation. We use soft and tough double-network elastomers tagged with mechanofluorescent probes to understand the role of damage by sacrificial bond scission on their mechanical durability and fracture toughness. Damage accumulation and localization ahead of the crack tip depend on the areal density of sacrificial bonds, as well as on the applied load (<i>i.e.</i>, cyclic or monotonic). This information serves to engineer fatigue resistant elastomers, understand fracture mechanisms, and reduce the environmental footprint of the polymer industry.</p>

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