Study of prefracture states of rigid polymers. 2. Elastic limit and strength

1977 ◽  
Vol 12 (2) ◽  
pp. 167-172 ◽  
Author(s):  
N. I. Shishkin ◽  
M. F. Milagin
Keyword(s):  
Elastic Limit ◽  
Rigid Polymers

On the nominal transverse shear strain to characterize the severity of creasing

TAPPI Journal ◽  
2018 ◽  
Vol 17 (04) ◽  
pp. 231-240
Author(s):  
Douglas Coffin ◽  
Joel Panek
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Elastic Limit ◽  
Experimental Results ◽  
Transverse Shear Strain ◽  
Maximum Strain ◽  
Machine Direction ◽  
Engineering Approach ◽  
Wide Range ◽  
Analytic Expression

A transverse shear strain was utilized to characterize the severity of creasing for a wide range of tooling configurations. An analytic expression of transverse shear strain, which accounts for tooling geometry, correlated well with relative crease strength and springback as determined from 90° fold tests. The experimental results show a minimum strain (elastic limit) that needs to be exceeded for the relative crease strength to be reduced. The theory predicts a maximum achievable transverse shear strain, which is further limited if the tooling clearance is negative. The elastic limit and maximum strain thus describe the range of interest for effective creasing. In this range, cross direction (CD)-creased samples were more sensitive to creasing than machine direction (MD)-creased samples, but the differences were reduced as the shear strain approached the maximum. The presented development provides the foundation for a quantitative engineering approach to creasing and folding operations.

Regularities and properties of instrumented indentation diagrams obtained by ball-shaped indenter

2020 ◽  
Vol 86 (5) ◽  
pp. 43-51
Author(s):  
V. M. Matyunin ◽  
A. Yu. Marchenkov ◽  
N. Abusaif ◽  
P. V. Volkov ◽  
D. A. Zhgut
Keyword(s):  
Yield Strength ◽  
Ultimate Strength ◽  
Elastoplastic Deformation ◽  
Elastic Limit ◽  
Tensile Tests ◽  
Indentation Load ◽  
International Standards ◽  
Instrumented Indentation ◽  
Indentation Methods ◽  
Special Points

The history of appearance and the current state of instrumented indentation are briefly described. It is noted that the materials instrumented indentation methods using a pyramid and ball indenters are actively developing and are currently regulated by several Russian and international standards. These standards provide formulas for calculating the Young’s modulus and hardness at maximum indentation load. Instrumented indentation diagrams «load F – displacement α» of a ball indenter for metallic materials were investigated. The special points on the instrumented indentation diagrams «F – α» loading curves in the area of elastic into elastoplastic deformation transition, and in the area of stable elastoplastic deformation are revealed. A loading curve area with the load above which the dF/dα begins to decrease is analyzed. A technique is proposed for converting «F – α» diagrams to «unrestored Brinell hardness HBt – relative unrestored indent depth t/R» diagrams. The elastic and elastoplastic areas of «HBt – t/R» diagrams are described by equations obtained analytically and experimentally. The materials strain hardening parameters during ball indentation in the area of elastoplastic and plastic deformation are proposed. The similarity of «HBt – t/R» indentation diagram with the «stress σ – strain δ» tensile diagrams containing common zones and points is shown. Methods have been developed for determining hardness at the elastic limit, hardness at the yield strength, and hardness at the ultimate strength by instrumented indentation with the equations for their calculation. Experiments on structural materials with different mechanical properties were carried out by instrumented indentation. The values of hardness at the elastic limit, hardness at the yield strength and hardness at the ultimate strength are determined. It is concluded that the correlations between the elastic limit and hardness at the elastic limit, yield strength and hardness at the yield strength, ultimate tensile strength and hardness at the ultimate strength is more justified, since the listed mechanical characteristics are determined by the common special points of indentation diagrams and tensile tests diagrams.

On the determination and optimization of apparent “elastic limit” of kirigami metallic glasses

2021 ◽  
Vol 609 ◽  
pp. 412901
Author(s):  
K. Chen ◽  
M. Yuan ◽  
H.M. Zheng ◽  
S.H. Chen
Keyword(s):  
Metallic Glasses ◽  
Elastic Limit

scholarly journals Pulmonary Stretch and Lung Mechanotransduction: Implications for Progression in the Fibrotic Lung

2021 ◽  
Vol 22 (12) ◽  
pp. 6443
Author(s):  
Alessandro Marchioni ◽  
Roberto Tonelli ◽  
Stefania Cerri ◽  
Ivana Castaniere ◽  
Dario Andrisani ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Spontaneous Breathing ◽  
Elastic Limit ◽  
Physiological Stress ◽  
Fibrous Tissue ◽  
Ventilatory Support ◽  
Biological Response ◽  
Alveolar Epithelium ◽  
Strain Curve ◽  
Mechanical Forces

Lung fibrosis results from the synergic interplay between regenerative deficits of the alveolar epithelium and dysregulated mechanisms of repair in response to alveolar and vascular damage, which is followed by progressive fibroblast and myofibroblast proliferation and excessive deposition of the extracellular matrix. The increased parenchymal stiffness of fibrotic lungs significantly affects respiratory mechanics, making the lung more fragile and prone to non-physiological stress during spontaneous breathing and mechanical ventilation. Given their parenchymal inhomogeneity, fibrotic lungs may display an anisotropic response to mechanical stresses with different regional deformations (micro-strain). This behavior is not described by the standard stress–strain curve but follows the mechano-elastic models of “squishy balls”, where the elastic limit can be reached due to the excessive deformation of parenchymal areas with normal elasticity that are surrounded by inelastic fibrous tissue or collapsed induration areas, which tend to protrude outside the fibrous ring. Increasing evidence has shown that non-physiological mechanical forces applied to fibrotic lungs with associated abnormal mechanotransduction could favor the progression of pulmonary fibrosis. With this review, we aim to summarize the state of the art on the relation between mechanical forces acting on the lung and biological response in pulmonary fibrosis, with a focus on the progression of damage in the fibrotic lung during spontaneous breathing and assisted ventilatory support.

Elastic limit load estimation including similarity approach for different end conditioned conical shells with high semi-vertex angle under axial compression

2020 ◽  
Vol 149 ◽  
pp. 106543
Author(s):  
Haluk Yılmaz ◽  
Erdem Özyurt ◽  
Asım Önder ◽  
Petr Tomek
Keyword(s):  
Axial Compression ◽  
Elastic Limit ◽  
Limit Load ◽  
Vertex Angle ◽  
Load Estimation ◽  
Conical Shells

Bilayer nanocomposite molecular coatings from elastomeric/rigid polymers: fabrication, morphology, and micromechanical properties

2001 ◽  
Vol 167 (1) ◽  
pp. 227-242 ◽  
Author(s):  
Igor Luzinov ◽  
Daungrut Julthongpiput ◽  
Paul D. Bloom ◽  
Valerie V. Sheares ◽  
Vladimir V. Tsukruk
Keyword(s):  
Micromechanical Properties ◽  
Rigid Polymers

Spatially resolved NMR of rigid polymers and elastomers

1994 ◽  
Vol 12 (2) ◽  
pp. 301-304 ◽  
Author(s):  
F. Weigand ◽  
C. Fülber ◽  
B. Blümich ◽  
H.W. Spiess
Keyword(s):  
Spatially Resolved ◽  
Rigid Polymers

scholarly journals Effect of upstream boundary conditions on stability of fiber spinning in the highly elastic limit

2002 ◽  
Vol 46 (4) ◽  
pp. 1023 ◽  
Author(s):  
Michael Renardy
Keyword(s):  
Boundary Conditions ◽  
Elastic Limit ◽  
Fiber Spinning
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