Papers by Author: Peter W.R. Beaumont

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Authors: Peter W.R. Beaumont
Abstract: The demands made on structural composite materials in modern design are increasingly stringent. Greater performance, lower costs, increased reliability and safety all require that the design engineer knows more and more of the material systems available. Bringing together new knowledge contained in constitutive models of continuum design and empirical information from a girth of experience is proving to be difficult because the number of service and process variables required for sophisticated, optimal design is becoming increasingly larger. Understanding Structural Integrity (SI) provides the key to the successful design, certification, and safety of large composite structures and engineering composite materials. This is because SI analysis treats simultaneously the design, the materials used, figures out how best components and parts are joined, and takes service duty into account. But predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic failure of the structure will occur remains an unsolved mystery.
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Authors: Peter W.R. Beaumont, Hideki Sekine
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Authors: Hideki Sekine, Peter W.R. Beaumont
Abstract: A micromechanical theory of macroscopic stress-corrosion cracking in unidirectional glass fiber-reinforced polymer composites is proposed. It is based on the premise that under tensile loading, the time-dependent failure of the composites is controlled by the initiation and growth of a crack from a pre-existing inherent surface flaw in a glass fiber. A physical model is constructed and an equation is derived for the macroscopic crack growth rate as a function of the apparent crack tip stress intensity factor for mode I. Emphasis is placed on the significance of the size of inherent surface flaw and the existence of matrix crack bridging in the crack wake. There exists a threshold value of the stress intensity factor below which matrix cracking does not occur. For the limiting case, where the glass fiber is free of inherent surface flaws and matrix crack bridging is negligible, the relationship between the macroscopic crack growth rate and the apparent crack tip stress intensity factor is given by a simple power law to the power of two.
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Authors: Peter W.R. Beaumont
Abstract: Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Fitness considerations for long-life implementation of aerospace composites include understanding phenomena such as fatigue, creep and stress corrosion cracking that affect reliability, life expectancy, and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined; furthermore, SI takes into account service duty.
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