A study of the effects of time and temperature on the fiber/matrix interface strength using the microbond test

1997 ◽  
Vol 57 (8) ◽  
pp. 991-994 ◽  
Author(s):  
Alexander Straub ◽  
Michael Slivka ◽  
Peter Schwartz
Keyword(s):  
Interface Strength ◽  
Matrix Interface ◽  
Microbond Test ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Measuring Interface Strength in Single Fiber Composites: The Effect of Stress Concentrations

2000 ◽  
Vol 629 ◽  
Author(s):  
G. A. Holmes ◽  
R. C. Peterson
Keyword(s):  
Fragment Length ◽  
Interface Strength ◽  
Matrix Interface ◽  
Stress Concentrations ◽  
New Model ◽  
Testing Rate ◽  
Mechanics Model ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

ABSTRACTFiber-matrix interface strength is known to be a critical factor in controlling the long-term performance of structural composites. This parameter is often obtained by using the average fragment length data generated from the single-fiber fragmentation test (SFFT). The interfacial shear strength is then determined by using this data in a micro-mechanics model that describes the shear-stress transfer process between the matrix and the fiber. Recently, a non-linear viscoelastic micro-mechanics model was developed to more accurately account for the matrix material properties. This new model indicates that the interface strength is dependent on the testing rate. Experimentally, it has been shown that the final fragment length distribution in some systems is dependent on the testing rate. However, data analysis using the new model indicates that the distribution change with testing rate is promoted by the presence of high stress concentrations at the end of the fiber fragments. From the model, these stress concentrations were found to exist at very low strain values. Experimentally, the fragment distributions obtained from specimens tested by different testing rates were found to be significantly different at strain values well below the strain values required to complete the test. These results are consistent with the research of Jahankhani and Galiotis and finite element calculations performed by Carrara and McGarry. These authors concluded that stress concentrations can promote failure of the fiber-matrix interface on the molecular level. Our results support this conclusion. In addition, our research results suggest that altering the SFFT testing rate can lower the magnitude of these stress concentrations and minimize failure of the fiber-matrix interface.

scholarly journals Sensitivity Analysis of Fiber-Matrix Interface Parameters in an SMC Composite Damage Model

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 544 ◽  
Author(s):  
Johannes Görthofer ◽  
Malte Schemmann ◽  
Thomas Seelig ◽  
Andrew Hrymak ◽  
Thomas Böhlke
Keyword(s):  
Glass Fibers ◽  
Damage Model ◽  
Interface Strength ◽  
Strength Distribution ◽  
Interface Debonding ◽  
Matrix Interface ◽  
Molding Compound ◽  
Fiber Matrix Interface ◽  
Fiber Matrix ◽  
Interface Parameters

This contribution shortly introduces the anisotropic, micromechanical damage model for sheet molding compound (SMC) composites presented in the authors’ previous publication [1]. As the considered material is a thermoset matrix reinforced with long (≈25 mm) glass fibers, the leading damage mechanisms are matrix micro-cracking and fiber-matrix interface debonding. Those mechanisms are modeled on the microscale and within a Mori-Tanaka homogenization framework. The model can account for arbitrary fiber orientation distributions. Matrix damage is considered as an isotropic stiffness degradation. Interface debonding is modeled via a Weibull interface strength distribution and the inhomogeneous stress distribution on the lateral fiber surface. Hereby, three independent parameters are introduced, that describe the interface strength and damage behavior, respectively. Due to the high non-linearity of the model, the influence of these parameters is not entirely clear. Therefore, the focus of this contribution lies on the variation and discussion of the above mentioned interface parameters.

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