Brittle fracture surfaces

A. Hansen, J. Origin of the universal roughness exponent of brittle fracture surfaces stress-weighted percolation in the damage zone. Phys. Rev. Lett. 90, 045504 (2003)... 

Conclusions. Examination of the failed pipe clamp revealed the presence of brittle fracture surfaces as well as an extensive array of branched transgranular cracks. The identification of the clamp material indicated it was a forged 304 stainless steel component... 

We conclude that plane strain alone does not necessarily cause brittleness even though brittle fracture surfaces can always be characterized as having failed in plane strain. One possible way to relieve plane strain is to include rubbery materials. 

Name four features that are seen on brittle fracture surfaces. 

FIGURE 24.18. SEMicrograph of a brittle fracture surface after [65]. 

Brittle fracture surface of failed crutch showing rivet and flutes on inner surface. 

The traditional method to study heterogeneous materials is to produce brittle fracture surfaces. This is usually done at low temperatures to avoid plastic deformation, which would hide the morphology. The fractme path occasionally follows structural details so that they become... 

J. J. Mecholsky, D. E. Passoja, and K. S. Feinberg-Ringel, Quantitative Analysis of Brittle Fracture Surfaces Using Fractal Geometry, J. Am. Ceram. Soc., 72 60-65 (1989). 

Surfaces give information on material morphology only in seldom cases (e.g., crystalline polymers crystallized from solution or melt). But specially prepared surfaces can yield information on the internal morphology of the material, for instance, brittle fracture surfaces or selectively etched... 

PC, brittle fracture surface with an unusual regular deformation pattern ... 

PET with mineral (basalt) fibers, brittle fracture surface [2] ... 

There are similarities in epe and See with respect to the brittle fracture surface mode in a corrosive medium and mecharucaUy, both have a tensile stiess component that influences crack opening. The cyclic stiess range for epe is a dynamic process that induces crack initiation on the surface of the metallic component. If the component is exposed to a corrosive solution, then the combination of the cyclic stress and environment accelerate cracking and reduce fatigue life. 

Fracture mechanics considerations, summarized for polymers by Kausch [40,41], permit determination of the effect of defects on the fracture stress, or tensile strength, of bulk polymers and polymer fibers. It is important that such detailed study be performed on the original or primary fracture surfaces, which are the only surfaces which relate to the tensile stress. This is generally done by examining both failure surfaces to ensure that they are a matched pair. An example of matched, primary fracture surfaces was shown earlier (Fig. 4.29). In that case, a definite defect site was observed in the brittle fracture surface. Such assessment provides the structure-property information needed to modify the process and produce fibers with higher strengths. 

Besides the methods noted above, study of the microstmcture of the surface using SEM, and techniques for studying the fracture surface using the frozen section method (the method whereby soft green sheet containing plastic is chiUed at low temperature and is cut to achieve a brittle fracture surface) are frequently used. Evaluation using mercury porosimetry where mercury is injected into the sample is an effective technique for comparing... 

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