Research Outputs (Mechanical, Industrial and Aeronautical Engineering)
Permanent URI for this collectionhttps://wiredspace.wits.ac.za/handle/10539/21344
For information on accessing School of mechanical, industrial and aeronautical engineering Research Articles content please contact Salome Potgieter by email : salome.potgieter@wits.ac.za or Tel : 011 717 1961
Browse
2 results
Search Results
Item 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.Item 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.