S-N behavior has been a backbone of material fatigue life studies since the 19th century. Numerous S-N curve models have been produced but they have been arbitrarily chosen in numerous research works dominantly for composite materials. In this paper, they were critically reviewed and evaluated for capability using the following criteria: data fitting capability, efficiency of curve fitting, applicability to data sets at various stress ratios (−0.43, −1, −3, 0.1, and 10), representability of fatigue damage at failure, and satisfaction of the initial boundary condition. The S-N curve models were found to be in two categories-one for fatigue data characterization independent of stress ratio, and the other for those designed for predicting the effect of stress ratio. The models proposed by Weibull, Sendeckyj, and Kim and Zhang for fatigue data characterization appeared to have the best capabilities for experimental data obtained from Weibull for R = −1, from Sendeckyj for R = 0.1, and from Kawai and Itoh (for R = −0.43, −3, and 10). The Kim and Zhang model was found to have an advantage over the Weibull and the Sendeckyj models for representing the fatigue damage at failure. The Kohout and Vechet model was also found to have a good fitting capability but with an inherent limitation for shaping the S-N curve at some stress ratios (e.g., R = −0.43). The S-N curve models developed for predicting the effect of stress ratio were found to be relatively inferior in data fitting capability to those developed directly for fatigue data characterization.

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A pilot scheme was developed to integrate the distribution of readymade near spectacles into primary eye care (PEC) delivery in 6 primary health care (PHC) facilities in Zanzibar, East Africa. With the aim of scaling it up to national level the scheme was evaluated in terms of relevance, effectiveness, equality, sustainability and replicability, MethodsSix Medical Officers were trained in ocular anatomy, history taking, blindness definitions, ocular abnormalities, preventable blindness, distance visual acuity (VA), near VA, eye examination, record keeping and referral criteria. Each clinic was supplied with 200 near spectacles. The evaluation team revisited the units six months later to assess the scheme. ResultsThe evaluation team recommendations included: a structured approach to planning from the outset, facility selection criteria, raising awareness through community meetings, funding through a revolving fund and the introduction of referral monitoring systems. 372 of the 574 patients attending the facilities had eye complaints; 285 eye infections, 29 distance vision problems and 173 near vision problems. 173 near vision spectacles were dispensed and 74 people were referred. All medical officers and participants recommended continuing with the scheme. ConclusionsThe project is highly relevant and timely given that presbyopia is now a priority with the World Health Organisation. The scheme could easily be adopted at the national level in Zanzibar and other areas in East Africa.

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Abstract. An S-N curve is essential not only for describing fatigue results from tests for un-notched specimens but also for theorization of fatigue life predictions for real situation applications. The fatigue life predictions associated with fatigue damage cannot be adequately conducted without an S-N curve model. In this paper, criteria for evaluating S-N curve models are suggested, and an S-N curve model previously proposed by Kim and Zhang (2001) was accordingly refined with damage concept for various stress ratios. A practical method for finding model parameters is presented with examples.

The A320 aft fixed fairing is an advanced composite structure fabricated from laminate carbon woven and combines with honeycomb core which is externally mounted on the flap track fairing as a wing part of Airbus aircraft. These flaps are movable control surfaces to widen up the surface of the wing in order to increase the lifting. This paper discussed on the inspection of A320 aft fixed fairing by using shearography NDT technique. Shearography technique reveals the stress-affected zone due to additional loading that can be realized by the laser speckle correlation on the inspected composite panel. This A320 aft fixed fairing is identified as a scrap composite panel which having different sizes and orientations of defect. The results showed that the changes of shearing direction in laser shearography technique are an effective means to reveal the defects propagation in the composite component. The shearing at Y-axes direction is able to detect the cracks at horizontal orientation while shearing at X-axis has successfully detects the cracks at vertical orientation. Therefore, shearography could be utilized as an alternative inspection for other NDT method for inspection of composite material.

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