Failure of composites

Sattar. S.A. and Kellogg, D.H. (1969). The effect of geometry on the mode of failure of composites in short beam shear test. In Composite Materials Testing and Design. ASTM STP 460, ASTM, Philadelphia, PA, pp. 62-71. 

Some materials might produce a unique failure surface providing measurements could be conducted under first stretch conditions in a state of equilibrium. Tschoegl (110), at this writing, is attempting to produce experimental surfaces by subjecting swollen rubbers to various multiaxial stress states. The swollen condition permits failure measurements at much reduced stress levels, and the time dependence of the material is essentially eliminated. Studies of this type will be extremely useful in establishing the foundations for extended efforts into failure of composite materials. 

Several studies of polymer/silane coupling agent interphases have involved the use of scanning electron microscopy (SEM) [5-7]. For example, Vaughan and Peek [6] have used SEM to examine fracture surfaces to determine the mode of failure of composite materials and to draw conclusions about interfacial interactions of various coupling agents and epoxide and polymer resin systems. 

The present paper aims to assess damage in UD GRP composites of various off-axis angles under axial loads. Damage analysis presented in this paper is drastically influenced by void content of the material and it assumes that there should be a direct relationship between the failure of composite material and its void content. 

A new approach to predict the failure of UD GRP composites has been developed in this paper. The direct relationship between the void propagation and failure of composite material has been successfully aehieved. The effeet of off-axis angle and loading level on void content was then mathematically described. 

Multiple fiber fracture prior to failure of composite... 

If gapping is too narrow and cannot accommodate the swelling, this situation leads to buckling, distortions, cracking, and other types of failure (Fig. 12.4-12.9) Clearly, for such distortions and mechanical failure of composite deck boards, a significant pressure/load should have been developed. It was determined that the... 

Recognizing that most failure criteria are limited in their accuracy [8,9], researchers worldwide have undertaken collaborative efforts to evaluate different failure criteria to determine their accuracy and applicability in order to find the best one [10]. These efforts, in particular the worldwide failure exercise in [10], have underlined the fact that despite the large number (over 20) of failure criteria, there is no single one that seems to capture failure of composites accurately for a wide range of loading situations and materials. However, they have pointed out that certain criteria are more accurate and/or have a wider range of applicability than others. Most notable among these are the Puck criterion and the LaRC 03 failure criterion. 

Post-first-ply failure, progressive failure of composite laminates... 

Tong L. Bearing failure of composite bolted joints with non-uniform bolt to washer clearance. Compos Part A 2000 31 609-15. 

NOTE THAT TITANIUM END STEPS WERE ALREADY SHORTENED DURING PRELIMINARY DESIGN. WITH UNIFORM STEPS 1.91 cm (0.75 IN.) LONG THROUGHOUT. PREMATURE FATIGUE FAILURE WOULD OCCUR AT A. FOLLOWED BY FAILURE OF COMPOSITE AT THE SAME (REDUCED) SECTION. 

Example 3. An example of mechanism competition is the failure of composite plies (Whiteside et al. 2012). There are three failure mechanisms for the composite ply and each of them results in a specific failure mode. The mechanisms include fiber tensile (/ ), matrix failure (/ ) and fiber kinking/splitting fktnkispin) models describing... 

Stress Corrosion Failure of Composite Long Rod Insulators, 4th International Symposium on High Voltage Engineering, Athens, 1993... 

This is illustrated in Fig. 37. From this it is argued that, for sufficiently thin adherends, the peeling stresses are not important. This approach may be applied to the failure of composite joints, where failure is due to the transverse stresses in the laminate as shown in Fig. 38, which also shows how profiling the adherend can reduce the peel stresses, change the failure mode, and hence increase joint strength. 

Bogetti, T. A., C. P. R. Hoppel, V. M. Harik, J. F. NewUl, and B. P. Bums, Predicting the nonlinear response and progressive failure of composite laminates. Compos Sci Technol,... 

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