This article provides an overview on the effects of fluids on the deformation and durability of polymeric composites. This subject is important for the ever-increasing application of composites in offshore structures, submersibles, and civil infrastructure. Since weight-gain data abound in the literature, it may be useful to recognize that a certain degree of correlation exists between some characteristic features of weight-gain data and the ability of a particular composite to retain its integrity under specified exposures to a certain fluid. In addition, this article provides records of fluid effects on deformation as well as on fluid-affected levels of static fatigue and fatigue lives in some specific circumstances.

Effects of Fluids on the Deformation, Strength and Durability of Polymeric Composites – An Overview

: This report presents a review of the effects of fluids on the response of polymeric composites. It contains a comprehensive listing of data regarding sorption processes, which are divided among several categories. Some categories are noted to be associated with reversible benign effects while others are correlated with irreversible phenomena that lead to property degradation and failure. In addition, the report contains several chapters that deal with specific aspects of fluid effects on mechanical properties. These aspects include creep, durability, strength and fatigue. (MM)

Effects of Fluids on Polymeric Composites—A Review

This article summarizes research on the transport processes of water vapor in polymeric composites, with emphasis on graphite-epoxies. In addition, results are presented on moisture induced damage with suggestions for the modeling of this phenomenon. It appears that moisture transport and damage are intricately coupled phenomena, which may reinforce each other to the detriment of the composite's durability.

Moisture in Composites: Sorption and Damage

6.05 – Environmentally Assisted Fatigue in the Gaseous Atmosphere

An investigation was conducted to determine the effect of various absorbed gaseous species on the adhesion and friction of tungsten. Experiments were conducted in a vacuum of 10−10 Torr with a hemispherical rider specimen [(100) tungsten] contacting a flat. The atomic planes of tungsten examined on the flat included the (100), (110), and the (210). The gases absorbed to these tungsten surfaces included hydrogen, oxygen, carbon dioxide, hydrogen sulfide, and a homologous series of hydrocarbons (methane through decane), as well as ethylene and acetylene. The results of the study indicate that the presence of any gas, even hydrogen, on the tungsten surface will reduce adhesion and friction. Less than a monolayer of oxygen adsorbed on tungsten is sufficient to reduce appreciably the friction of tungsten crystals. For hydrocarbons an increase in chain length (methane through decane) resulted in a progressive decrease in friction. Furthermore, with ethane, ethylene, and acetylene, friction decreased with an increase in the number of carbon‐to‐carbon bonds.

Influence of Chemisorbed Films of Various Gases on Adhesion and Friction of Tungsten

Environmental parameters effect on solid phase welding of metals under high vacuum with reference to functioning of spacecraft

Solid-Phase Welding of Metals under High Vacuum

High vacuum environment and vacuum outgassing time effects on magnesium alloys fatigue properties under constant load and reversed bending

Vacuum effects on fatigue properties of magnesium and two magnesium alloys.

Effects of torsional and flexural fatigue on the long-time Integrity of advanced graphite-epoxy structural composites have been investigated. Torsional fatigue tests were run at stress ratios of R = 0 (zero to maximum, repeated) and R = -1 (zero mean stress) on unidirectional, angleply, and woven graphite fiber materials in air and water at room temperature and at 74 C. Flexural fatigue tests (four-point bending) with R = -1 were run in air and water at room temperature, and with R = 0 in air. Results show that, in torsional cycling, both water environment and higher test temperature contribute to significant degradation of torsional stiffness. The degradation of stiffness from torsional stress cycling was observed to be much greater with R = -1 than with simple R = 0 cycling. The effect of environment also is greater in the fully reversed cycling. Flexural fatigue results on +/- 30 deg material show a large fatigue effect, with fatigue limits of less than 50% and 30% of the static failure strength for specimens tested under stress ratios of R = 0 and R = -1, respectively. Compliance measurements indicate that the final failures are preceded by damage initiation and accumulation, which begins at about 1% of the specimen life.

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H. T. Sumsion

Papers

Solid-Phase Welding of Metals under High Vacuum

Vacuum effects on fatigue properties of magnesium and two magnesium alloys.

Environmental Effects on Graphite-Epoxy Fatigue Properties