Abstract: The design, manufacture, and operation of thin-walled
pressure vessels must be based on maximum safe operating pressure
and an adequate factor of safety (FoS). This research paper first
reports experimental evaluation of longitudinal and hoops stresses
based on working pressure as well as maximum pressure; and then
includes a critical study of factor of safety (FoS) in the design of a
glass fiber pressure vessel. Experimental work involved the use of
measuring instruments and the readings from pressure gauges.
Design calculations involved the computations of design stress and
FoS; the latter was based on breaking strength of 55 MPa for the
glass fiber (pressure-vessel material). The experimentally determined
FoS value has been critically compared with the general FoS allowed
in the design of glass fiber pressure vessels.
Abstract: In this study, thermal elastic stress distribution occurred on long hollow cylinders made of functionally graded material (FGM) was analytically defined under thermal, mechanical and thermo mechanical loads. In closed form solutions for elastic stresses and displacements are obtained analytically by using the infinitesimal deformation theory of elasticity. It was assumed that elasticity modulus, thermal expansion coefficient and density of cylinder materials could change in terms of an exponential function as for that Poisson’s ratio was constant. A gradient parameter n is chosen between - 1 and 1. When n equals to zero, the disc becomes isotropic. Circumferential, radial and longitudinal stresses in the FGMs cylinders are depicted in the figures. As a result, the gradient parameters have great effects on the stress systems of FGMs cylinders.
Abstract: Tensile armour wires provide a flexible pipe's
resistance to longitudinal stresses. Flexible pipe manufacturers need
to know the effect of defects such as scratches and cracks, with
dimensions less than 0.2mm which is the limit of the current nondestructive
detection technology, on the fracture stress and fracture
strain of the wire for quality assurance purposes. Recent research
involving the determination of the fracture strength of cracked wires
employed laboratory testing and classical fracture mechanics
approach using non-standardised fracture mechanics specimens
because standard test specimens could not be manufactured from the
wires owing to their sizes. In this work, the effect of miniature
cracks on the fracture properties of tensile armour wires was
investigated using laboratory and finite element tensile testing
simulations with the phenomenological shear fracture model. The
investigation revealed that the presence of cracks shallower than
0.2mm is worse on the fracture strain of the wire.