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Arterial aneurism and stenosis are disorders that lead to circulation malfunction. Stenosis often leads to hypoxia of the organ depending on the affected artery, whilst aneurism can lead to dissection with known lethal consequences. On both cases, the pulse wave produced by the contracting heart is reflected at these discontinuities, and estimating the size of these reflected waves using wave intensity analysis (WIA) is the main aim of this work. We also aim to measure wave speed, or pulse wave velocity (PWV) as more commonly known within the discontinuities. We manufactured 4 stenosis and 4 aneurism silicon sections, connected one at a time to a mother tube, and tested in vitro. Pressure and flow were measured proximal to the discontinuity and were used to calculate WIA. PWV was calculated using the foot to foot technique and also the classical Moens-Korteweg and Bramwell-Hill equations. Wave speed in an aneurism decreases, whereas it increases in a stenosis, all compared to the values determined in a standard mother tube. Presence of aneurisms resulted in a backward expansion whilst the presence of stenosis resulted in a backward compression wave, which related linearly to the size of the discontinuity. Larger aneurisms and smaller stenosis cause an increase in wave reflection.

This paper describes the pressure wave propagation and reflection phenomenon in the aorta and the brachial artery to reproduce the brachial artery pressure and the strain imposed on the cuff external wall using thick wall tube assumption for the aorta. The effects of variations in aortic radius, thickness, heart rate and cuff pressure on the brachial artery pressure contours and pneumatic cuff strain contours were investigated The thick wall tube assumption for the aorta will improve the accuracy of the results and give an indication about the error involved when using thin wall tube assumption. The results indicate that there are some differences between the trends and shapes of the curves when using thick wall assumption. This difference could be as high as 3% for the eight feature points extracted from the pressure and strain contours. These feature points are the time duration before the deflection marking the arrival of the incident and reflected wave, the peak of the first and second pressure deflection minus the diastolic pressure, the peak of the first and second strain deflection minus the strain at diastolic pressure. These features points are used to calculate the brachial augmentation indices and the time lag which are used as a measure of arterial stiffness.

In this paper an investigation has been made into the effect of residual stresses on the vibration characteristics of thin rectangular clamped plate. General frequency equations with and without the effect of residual stresses due to multi-lines of heating or welding along the length and width of the plate have been obtained. The validity of the equations obtained was checked with available special solutions with a good agreement.