School of Mechanical, Industrial and Aeronautical Engineering

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Browsing School of Mechanical, Industrial and Aeronautical Engineering by Author "Carpenter, H.W."

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    The effect of residual stresses and wind configuration on the allowable pressure of thick-walled GFRP pipes with closed ends.
    (Springer, 2015) Carpenter, H.W.; Reid, R.G.; Paskaramoorthy, R.
    An investigation into the benefits of winding thick-walled glass fibre reinforced plastic (GFRP) pipes with two layers of different winding angles is presented. It is shown that layered pipes allow significantly greater internal pressures to be carried than can be achieved by pipes wound only at +/- 55 degrees if process induced residual stresses are ignored. It was found, also, that residual stresses severely reduce the allowable operating pressure of GFRP pipes. The reduction was most significant for the layered pipes, however, and this severely impacts on their utility. The most efficient pipe was nevertheless found to be a layered pipe, wound with a +/- 65 degrees/+/- 47 degrees combination. This pipe gives a 12 % improvement on the allowable pressure of the +/- 55 degrees pipe. This small performance benefit is achieved at the cost of significantly greater manufacturing complexity, and so the +/- 55 degrees pipe is probably still the most practical wind configuration.
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    Extension of the layer removal technique for the measurement of residual stresses in layered anisotropic cylinders.
    (Springer, 2014-09) Carpenter, H.W.; Reid, R.G.; Paskaramoorthy, R.
    An extension of the layer removal technique is presented that allows the residual stresses within multilayered anisotropic pipes of any wall thickness to be determined. The method inherently satisfies the self-equilibrium requirement and limits the effects of measurement errors to the region local to the error. The thickness of each layer that is removed need not be uniform and is entirely independent of the thickness of each ply of material. Four example problems are considered. The first three allow results to be compared between the present method and previous work. The fourth problem demonstrates the method on a thick walled anisotropic pipe built up of +45°/-45° plies for which no solution was previously available.
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    Measurement of the Distribution of Residual Stresses in Layered Thick-Walled GFRP Pipes.
    (Springer, 2014-11) Carpenter, H.W.; Reid, R.G.; Paskaramoorthy, R.
    The objective of this study is to measure the axial, circumferential, shear and radial residual stress distributions in three thick-walled glass fibre reinforced plastic (GFRP) filament-wound pipes, two of which are layered. The measurement of residual stresses was carried out using a recently published layer removal method which overcomes the limitations of previous techniques and can be applied to layered anisotropic pipes of any wall thickness. Layers of approximately 0.3 mm thickness were incrementally ground from the outer surface of the pipes. The resulting strains were measured on the inner surfaces. A least-squares polynomial was fitted to each measured data set, and used to calculate the corresponding stress distributions. All of the resulting axial, hoop and shear stress distributions adhere to the requirement of self-equilibrium and the radial stress distributions all vanish to zero at the inner and outer surfaces. The radial stresses of the layered pipes showed a tendency to have two peaks, one for each layer, a consequence of the two-stage manufacturing process of these pipes. The measured axial and hoop stresses of all three pipes were similar at the inner surfaces despite significant differences in the stiffnesses in the principal directions arising from different wind angles.
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    The response of layered anisotropic tubes to centrifugal loading.
    (Elsevier, 2016-04) Carpenter, H.W.; Reid, R.G.
    The displacement-based elastic solution for layered anisotropic tubes is extended to allow for the presence of centrifugal loading. The additional terms in the stress-strain equations derived in this work are validated by comparing the results obtained using the current solution against those determined using finite element simulation of rotating thin and thick-walled glass fibre reinforced plastic tubes of arbitrary anisotropic lay-up. The solution is presented in such a form that it can be utilised to determine the linear thermo-mechanical behaviour of rotating tubes with anisotropic lay-up, subjected to any combination of internal and external axisymmetric pressure, axial loading, torsional loading, and constant temperature change.