Multiscale shear-strain gradient for detecting delamination in composite laminates

2013 ◽  
Vol 103 (10) ◽  
pp. 101910 ◽  
Author(s):  
M. S. Cao ◽  
W. Ostachowicz ◽  
M. Radzieński ◽  
W. Xu
Keyword(s):  
Shear Strain ◽  
Strain Gradient ◽  
Composite Laminates

Interply Behavior Exhibited in Compliant Filamentary Composite Laminates

1982 ◽  
Vol 55 (4) ◽  
pp. 1078-1094 ◽  
Author(s):  
J. L. Turner ◽  
J. L. Ford
Keyword(s):  
Shear Strain ◽  
Composite Laminates ◽  
Matrix Material ◽  
Matrix Composites ◽  
Efficient Manner ◽  
Strain Behavior ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Extensional Strain ◽  
Interlaminar Shear

Abstract Cord-rubber composite systems allow a visualization of interply shear strain effects because of the compliant nature of the matrix material. A technique termed the pin test was developed to aid this visualization of interply shear strain. The pin test performed on both flat pads and radial tires shows that interlaminar shear strain behavior in both types of specimens is similar, most of the shear strain being confined to a region approximately 10 interly rubber thicknesses from the edge. The observed shear strain is approximately an order of magnitude greater than the applied extensional strain. A simplified mathematical model, called the Kelsey strip, for describing such behavior for a two-ply (±θ) cord-rubber strip has been formulated and demonstrated to be qualitatively correct. Furthermore, this model is capable of predicting trends in both compliant and rigid matrix composites and allows for simplified idealizations. A finite-element code for dealing with such interply effects in a simple but efficient manner predicts qualitatively correct results.

Fatigue of Cord-Rubber Composites: V. Cord Reinforcement Effect

2004 ◽  
Vol 77 (4) ◽  
pp. 593-610 ◽  
Author(s):  
J. H. Song ◽  
F. Costanzo ◽  
B. L. Lee
Keyword(s):  
Shear Strain ◽  
Composite Laminates ◽  
Composite Laminate ◽  
Failure Modes ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Temperature History ◽  
Rubber Matrix ◽  
Fatigue Lifetime ◽  
Dynamic Creep

Abstract Fatigue behavior of cord-rubber composite materials forming the belt region of radial pneumatic tires has been characterized to assess their dependence on stress, strain and temperature history as well as materials composition and construction. Estimated at various levels of stress amplitude were the fatigue life, the extent and rate of resultant strain increase (“dynamic creep”), cyclic strains at failure, and specimen temperature. Reflecting their matrix-dominated failure modes, such as cord-matrix debonding and delamination, composite laminates with different cord reinforcements showed the same S-N relationship as long as they were constructed with the same rubber matrix, the same cord angle, similar cord volume, and the same ply lay-up. The interply shear strain of 2-ply ‘tire belt’ composite laminate under circumferential tension was affected by twisting of specimen due to tension-bending coupling. However, a critical level of interply shear strain, which governs the gross failure of composite laminate due to the delamination, appeared to be independent of different lay-up of 2-ply vs symmetric 4-ply configuration. Because of much lower values of single cycle strength (in terms of gross fracture load per unit width), the composite laminates with larger cord angle and the 2-ply laminates exhibited exponentially shorter fatigue lifetime, at a given stress amplitude, than the composite laminates with smaller cord angle and 4-ply symmetric laminates, respectively. Maximum cyclic strain of composite laminates at failure, which measures the total strain accumulation for gross failure, was independent of stress amplitude and close to the level of static failure strain. For all composite laminates under study, a linear correlation could be established between the temperature rise rate and dynamic creep rate which was, in turn, inversely proportional to the fatigue lifetime.

scholarly journals Free Edge Strain Concentrations in Real Composite Laminates: Experimental-Theoretical Correlation

1985 ◽  
Vol 52 (4) ◽  
pp. 787-793 ◽  
Author(s):  
C. T. Herakovich ◽  
D. Post ◽  
M. B. Buczek ◽  
R. Czarnek
Keyword(s):  
Finite Element ◽  
Shear Strain ◽  
Composite Laminates ◽  
Critical Angle ◽  
Axial Strain ◽  
Free Edge ◽  
Experimental Results ◽  
Resin Matrix ◽  
Maximum Shear Strain ◽  
Isoparametric Finite Element

The magnitude of the maximum shear strain at the free edge of axially loaded [θ2/–θ2]s and [(± θ)2]s composite laminates was investigated experimentally and numerically to ascertain the actual value of strain concentration in resin matrix laminates and to determine the accuracy of finite element results. Experimental results using moire´ interferometry show large, but finite, shear strain concentrations at the free edge of graphite-epoxy and graphite-polyimide laminates. Comparison of the experimental results with those obtained using several different finite element representations showed that a four-node isoparametric finite element provided the best and most trouble-free numerical results. The results indicate that the ratio of maximum shear strain at the free edge to applied axial strain varies with fiber orientation and does not exceed nine for the most critical angle which is 15 deg.

Multiphase Constitutive Model of " Matrix-Strengthen Particle of Saturated Soil "

2010 ◽  
Vol 168-170 ◽  
pp. 1098-1101
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang ◽  
Zhe Li
Keyword(s):  
Particle Size ◽  
Constitutive Model ◽  
Shear Strain ◽  
Strain Gradient ◽  
Strain Energy ◽  
Continuum Models ◽  
Internal Length ◽  
Micro Scale ◽  
The Matrix ◽  
Shear Strain Energy

In this article soil is treated as non-uniform material including two parts : the matrix particles and the reinforcement particles. Through soil shear strain energy and micro-crack assumptions, we establish a multiphase constitutive model connecting macro and micro scale based on classical continuum models, which includes the strain gradient, internal length scales and particle size. This model have been verified reasonable by artificial soil experiment.

Shear Strain Gradient in Cu/Nb Nanolaminates: Strain Accommodation and Chemical Mixing

2021 ◽  
Author(s):  
Xiaolong Ma ◽  
Bharat Gwalani ◽  
Jinhui Tao ◽  
Mert Efe ◽  
Matthew Olszta ◽  
...  
Keyword(s):  
Shear Strain ◽  
Strain Gradient ◽  
Chemical Mixing
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