Fracture toughness and R-Curve behavior of laminated brittle-matrix composites

1998 ◽  
Vol 29 (10) ◽  
pp. 2483-2496 ◽  
Author(s):  
D. R. Bloyer ◽  
R. O. Ritchie ◽  
K. T. Venkateswara Rao
Keyword(s):  
Fracture Toughness ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites

Evaluation on the fracture toughness and strength of fiber reinforced brittle matrix composites

1998 ◽  
Vol 12 (3) ◽  
pp. 370-379 ◽  
Author(s):  
Yong-Hoon Cha ◽  
Kyoung-Suk Kim ◽  
Duck-Joong Kim
Keyword(s):  
Fracture Toughness ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Brittle Matrix ◽  
Brittle Matrix Composites

Effect of Fiber Extensibility on the Fracture Toughness of Short Fiber or Brittle Matrix Composites

1992 ◽  
Vol 45 (8) ◽  
pp. 377-389 ◽  
Author(s):  
L. K. Jain ◽  
R. C. Wetherhold
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Fiber Orientation ◽  
Crack Opening ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Pull Out ◽  
General Terms ◽  
Brittle Matrix Composites ◽  
Fiber Orientation Distribution

A micromechanical model based on probabilistic principles is proposed to determine the effective fracture toughness increment and the bridging stress-crack opening displacement relationship for brittle matrix composites reinforced with short, poorly bonded fibers. Emphasis is placed on studying the effect of fiber extensibility on the bridging stress and the bridging fracture energy, and to determine its importance in cementitious matrix composites. Since the fibers may not be in an ideal aligned or random state, the analysis is placed in sufficiently general terms to consider any prescribable fiber orientation distribution. The model incorporates the snubbing effect observed during pull-out of fibers inclined at an angle to the crack face normal. In addition, the model allows the fibers to break; any fiber whose load meets or exceeds a single-valued failure stress will fracture rather than pull out. The crack bridging results may be expressed as the sum of results for inextensible fibers and an additional term due to fiber extensibility. An exact analysis is given which gives the steady-state bridging toughness G directly, but presents a non-linear problem for the bridging stress-crack opening (σb – δ) relationship. An approximate analysis is then presented which gives both G and σb – δ directly. To illustrate the effect of extensibility on bridging stress and fracture energy increment due to bridging fibers, a comparison with the inextensible fiber case is provided. It is found that effect of extensibility on fracture energy is negligible for common materials systems. However, extensibility may have a significant effect on the bridging stress-crack opening relationship. The effect of other physical and material parameters such as fiber length, fiber orientation and snubbing friction coefficient is also studied.

Improving Fracture Toughness of Brittle Matrix Composites Using End-Shaped Ductile Fibers: The Effects of Adhesion and Matrix Shrinkage

Materials ◽  
2003 ◽  
Author(s):  
Robert C. Wetherhold ◽  
Renee M. Bagwell
Keyword(s):  
Fracture Toughness ◽  
Bond Strength ◽  
Surface Chemistry ◽  
Matrix Composites ◽  
Release Agent ◽  
Brittle Matrix ◽  
Matrix Shrinkage ◽  
Pull Out ◽  
Brittle Matrix Composites ◽  
The Matrix

Ductile fibers are added to brittle matrix composites to increase the fracture toughness. To further improve fracture toughness, end shaped ductile fibers are added to act as anchors to utilize more of the fibers’ plasticity. Previous research focused on optimizing the volume of the shaped end for a given end shape family. Results indicate that for a given end shape family there is an optimum volume; above or below this volume results in a lower fracture toughness contribution. This research investigates two additional factors, adhesion of the matrix to the fiber and matrix shrinkage, and determines their effects on the fracture toughening of brittle matrix composites. The fiber was an annealed copper and the matrices used were a low shrinkage epoxy, a high shrinkage epoxy, and polyester. Results indicate that controlling the surface chemistry of the fiber can give an additional degree of freedom to the utilization of the fiber plasticity, although the importance of this control depends on the particular system. The fiber surface chemistry affects the bond strength and the adhesion; if the fiber cannot debond from the matrix, then shaping the end does not permit use of the plastic potential. Depending on the system, the adhesion and bond strength of the matrix to the fiber significantly affects the amount of fiber plasticity utilized. To determine the effects of friction and matrix shrinkage on the utilization of the fiber plasticity, release agent was applied to the end shaped fibers to reduce the adhesion, bond strength, and friction during pull out. Results indicate that frictional work and adhesion has a large impact on the utilization of the fiber plasticity; with release agent, the end shaped fiber utilizes little of the fiber plasticity. Furthermore, this indicates that for the matrices investigated, matrix shrinkage has a minor influence on the utilization of the fiber plasticity.

scholarly journals Conditions for Pseudo Strain-Hardening in Fiber Reinforced Brittle Matrix Composites

1992 ◽  
Vol 45 (8) ◽  
pp. 390-398 ◽  
Author(s):  
Victor C. Li ◽  
Hwai-Chung Wu
Keyword(s):  
Fracture Toughness ◽  
Strain Hardening ◽  
Fiber Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Brittle Matrix ◽  
Strain Capacity ◽  
Brittle Matrix Composites ◽  
Composite Strain ◽  
Pseudo Strain Hardening

Apart from imparting increased fracture toughness, one of the useful purposes of reinforcing brittle matrices with fibers is to create enhanced composite strain capacity. This paper reviews the conditions underwhich such a composite will exhibit the pseudo strain-hardening phenomenon. The presentation is given in a unified manner for both continuous aligned and discontinuous random fiber composites. It is demonstrated that pseudo strain-hardening can be practically designed for both types of composites by proper tailoring of material structures.

The fracture toughness for first matrix cracking of a unidirectionally reinforced carbon/carbon composite material

1991 ◽  
Vol 6 (11) ◽  
pp. 2312-2317 ◽  
Author(s):  
Tatsuya Miyajima ◽  
Mototsugu Sakai
Keyword(s):  
Fracture Toughness ◽  
Theoretical Models ◽  
Carbon Composite ◽  
Matrix Cracking ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites ◽  
Carbon Composite Material ◽  
Reinforcing Fibers ◽  
C Fiber

The fracture toughness for first matrix cracking of a uniaxially reinforced C-fiber/C-matrix composite is investigated using a modified controlled surface flaw method. The theoretical models for first matrix cracking of brittle matrix composites including the stress intensity and the potential energy approaches are reviewed in the light of the experimental results. The sharing of the applied load between the reinforcing fibers and the brittle matrix along with extensive crack front debonding enhance the fracture toughness for first matrix cracking.

Brittle Matrix Composites 8

2006 ◽  
Author(s):  
A.M. Brandt ◽  
V.C. Li ◽  
I.H. Marshall
Keyword(s):  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites
Sign in / Sign up

Export Citation Format

Share Document