Determination of dissipated Energy in Fatigue Crack Propagation Experiments with Lock-In Thermography

Fatigue crack propagation in microcapsule - toughened epoxy

The addition of liquid-filled urea-formaldehyde (UF) microcapsules to an epoxy matrix leads to significant reduction in fatigue crack growth rate and corresponding increase in fatigue life. Mode-I fatigue crack propagation is measured using a tapered doublecantilever beam (TDCB) specimen for a range of microcapsule concentrations and sizes: 0, 5, 10, and 20% by weight and 50, 180, and 460 lm di...

High Temperature Fatigue Crack Propagation in INCONEL718

Thermal activation of fatigue crack growth: analysing the mechanisms of fatigue crack propagation in superalloys

A method for deriving apparent activation energies, Eapp, for fatigue crack growth (FCG) is presented. It is shown how these Eapp values can be used to analyse the main underlying mechanism causing the progression of the crack. The Eapp values for fatigue crack growth in air and vacuum, and with and without a dwell are obtained for a range of Ni based superalloys for turbine disc applications. ...

Stochastic modeling of fatigue crack propagation

This paper presents a stochastic model of fatigue-induced crack propagation in metallic materials. The crack growth rate predicted by the model is guaranteed to be non-negative. The model structure is built upon the underlying principle of Karhunen±Lo eve expansion and does not require solutions of stochastic di€erential equations in either Wiener integral or Itô integral setting. As such this ...

Lock-in Thermography Image Procesing

Composite materials have appropriate thermal properties for detection flaws by means of non-destructive infrared thermography methods. Infrared thermography methods are based on tracking heat flow that has been induced by flood lamps. Lock-in thermography, as one of infrared thermography methods, is used in detection of flaws. Surface of specimen is periodically heated by heat flow in form of s...