Fatigue Resistance of Natural Rubber in Compression

1982 ◽  
Vol 55 (2) ◽  
pp. 337-351 ◽  
Author(s):  
P. B. Lindley ◽  
A. Stevenson
Keyword(s):  
Natural Rubber ◽  
Fatigue Resistance ◽  
Strain Energy ◽  
Strain Energy Release ◽  
Maximum Tensile Stress ◽  
Maximum Deformation ◽  
Energy Release Rates ◽  
Strain Energy Release Rates ◽  
Crack Growth Rates

Abstract Repeated deformation of natural rubber cylinders in compression causes cracks to initiate at points of maximum tensile stress concentration (e.g., at bond edges). These cracks grow until all the rubber which at the maximum deformation bulges outside the original profile of the cylinder is removed. Crack growth rates (da/dN) and strain energy release rates (G) have been determined. G is substantially independent of crack length. The relation between da/dN and G appears to be a fundamental material property for use in the determination of fatigue lives. Shaping the force free surface improves fatigue resistance.

Three Stages of Fatigue Crack Growth in GFRP Composite Laminates

2000 ◽  
Vol 123 (1) ◽  
pp. 139-143 ◽  
Author(s):  
Jie Tong
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Energy Release ◽  
Crack Growth ◽  
Strain Energy ◽  
Strain Energy Release ◽  
Release Rates ◽  
Energy Release Rates ◽  
Three Stages ◽  
Strain Energy Release Rates

Multiple fatigue crack growth behavior has been studied in model transparent GFRP laminates. Detailed experimental observations have been made on the growth of individual fatigue cracks and on the evolution of cracks in off-axis layers in 0/90/±45S and ±45/90S laminates. Three stages of fatigue crack growth in the laminates have been identified: initiation, steady-state crack growth (SSCG), crack interaction and saturation. The results show that SSCG rate is essentially constant under constant load, independent of crack length and crack spacing. Finite element models have been developed and used to calculate the strain energy release rates associated with the off-axis matrix cracking. A correlation has been achieved between fatigue crack growth rates in off-axis layers and the total strain energy release rates.

A Standard Approach for Measuring Adhesion Energies in Stiction-Failed Microdevices

2006 ◽  
Author(s):  
Zayd C. Leseman ◽  
Steven Carlson ◽  
Xiaojie Xue ◽  
Thomas J. Mackin
Keyword(s):  
Strain Energy ◽  
Peel Test ◽  
Strain Energy Release ◽  
Piezo Actuator ◽  
Release Rates ◽  
Linear Elastic ◽  
Macro Scale ◽  
Energy Release Rates ◽  
Elastic Fracture ◽  
Strain Energy Release Rates

We present results from a new procedure developed to quantify the pull-off force and strain energy release rates associated with stiction-failure in microdevices. The method is analogous to a standard, macro-scale peel test, but carried out using micro-scale devices. Adhesion is initiated by lowering an array of microcantilevers that protrude from a substrate into contact with a separate substrate. Displacement is controlled by a piezo-actuator with sub-nm resolution while alignment is controlled using linear and tilt stages. An interferometric microscope is used to align the array and the substrate and to record deflection profiles and adhesion lengths during peel-off. This geometry is accurately modeled using linear elastic fracture mechanics, creating a robust, reliable, standard method for measuring adhesion energies in stiction-failed microdevices.

Effects of Crimped Fiber Paths on Mixed Mode Delamination Behaviors in Woven Fabric Composites

2016 ◽  
Author(s):  
Paul V. Cavallaro ◽  
Andrew Hulton ◽  
Mahmoud Salama ◽  
Melvin W. Jee
Keyword(s):  
Fracture Toughness ◽  
Energy Release ◽  
Mixed Mode ◽  
Strain Energy ◽  
Strain Energy Release ◽  
Woven Fabric ◽  
Woven Fabric Composites ◽  
Fabric Composites ◽  
Energy Release Rates ◽  
Strain Energy Release Rates

This research investigated the fracture toughness and crack propagation behaviors of woven fabric reinforced polymer (WFRP) composite laminates subjected to single and mixed mode loadings using numerical models. The objectives were to characterize the fracture behaviors and toughness properties at the fiber/matrix interfaces and to identify mechanisms that can be exploited for increasing delamination resistance. The mode-I and mode-II strain energy release rates GI and GII, the effective critical strain energy release rate, Gc_eff, (also known as the mixed mode fracture toughness) and crack growth stabilities were determined as functions of crimped fiber paths using meso-scale, 2D multi-continuum finite element models. Three variations of a plain-woven fabric architecture were considered; each having different crimped fiber paths. The presence of mixed-mode strain energy release rates at the meso-scale due to the curvilinear fiber paths was shown to influence the interlaminar fracture toughness and was explored for pure single-mode and mixed-mode global loadings. It was concluded that woven fabric composites provided a Fracture Toughness Conversion Mechanism (FTCM) and their toughness properties were dependent upon and varied with positon along the crimped fiber paths. The FTCM was identified as an advanced tailoring mechanism that can be further utilized to improve toughness and damage tolerance thresholds especially when the mode-II fracture toughness GIIc is greater than the mode-I fracture toughness GIc.

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