Composite damage prediction

Wiggenrad JEM, Zhang X, Davies GAO. Impact damage prediction and failure analysis of heavily loaded, blade-stiffened composite wing panels. Compos Struct 1990 45(2) ... 

Davies GAO, Zhang X. Impact damage prediction in composite structures. Int J Impact Eng 1995 6(l) 149-70. 

F. Alavi, Damage prediction of composites filled with irregular particles,pfiD Thesis (2013). 

An algorithm has been developed to predict the thermal conductivity degradation for a high thermal conductivity composite ( 555 W/m-K at room temperature) as a function of radiation dose and temperature [33]. The absence of irradiation data on CFCs of this type required the use of data from intermediate thermal conductivity materials as well as pyrolitic graphite to derive an empirical radiation damage term [14, 17, 19, 25, 26]. 

The above observations regarding the sensitivity of N, M, and Q and the relative insensitivity of to exact compositions of products from individual explosives lead to a variety of interesting observations. These involve (a) the present, calculational method (b) the ruby code and similar computer-based methods of calculation (c) effects of equilibria on actual detonation properties and, eventually, on damage effects and (d) methods which are widely used to intercompare the predicted performance of explosives. 

H.T. Chang, D.H. Allen Predicted dynamic response of a composite beam with history-dependent damage. Comp. Struct. 26, 575-580 (1987)... 

Testing of the composites themselves, or portions of them, are only one part of elevated temperature testing. Other areas requiring attention include failure analysis, damage accumulation, nondestructive evaluation, micro-structural evaluation, and information needed to validate predictive models. Chapter 4 refers to modeling efforts which require the collection of data on the constituents of the composites, i.e., the starting fibers, the matrices, and the fiber-matrix interfacial materials, to make predictions for properties of real composites. To use the models described previously, one must also know about the properties of the individual components. These issues are addressed in this section. 

The paper is presented in three parts. First, the tests employed to determine the mixed mode fracture envelope of a glass fibre reinforced epoxy composite adhesively bonded with either a brittle or a ductile adhesive are briefly described. These include mode I (DCB), and mixed mode (MMB) with various mixed mode (I/II) ratios. In the second part of the paper different structural joints will be discussed. These include single and double lap shear and L-specimens. In a recent European thematic network lap shear and double lap shear composite joints were tested, and predictions of failure load were made by different academic and industrial partners [9,10]. It was apparent that considerable differences existed between different analytical predictions and FE analyses, and correlation with tests proved complex. In particular, the progressive damage development in assemblies bonded with a ductile adhesive was not treated adequately. A more detailed study of damage mechanisms was therefore undertaken, using image analysis combined with microscopy to examine the crack tip strain fields and measure adherend displacements. This is described below and correlation is made between predicted displacements and failure loads, based on the mixed mode envelope determined previously, and measured values. 

The ultimate success on the road to accurate, reliable and realistic lifetime prediction methods for composite materials may be found in damage mechanics. However, more experimental efforts are necessary to develop and validate the micro mechanical theory. 

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