Papers by Keyword: Limit Pressure

Abstract: Insitu tests are mostly considered to be cheap, quick and they are used sometimes to measure certain insitu properties ,such as modulus and lateral stress not readily evaluated by laboratory tests. A form of insitu investigation which is receiving increasing recognition is the pressuremeter. The pressuremeter devices and tests experienced extensive development in both , the technical aspects and the interpretation theories which been used extensively in several testing laboratories . In the present research a comparison between different theories used to evaluate the pressuremeter tests where different were found when using different results for the same test .

Abstract: Using the finite difference code FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) and UST (Unified Strength Theory), the influence of the intermediate principal stress effect on the problems of flat punch are analyzed in this paper. The values of the ultimate bearing capacity resulting from numerical analyses and the analytical solution of Prandtl’s strip punch problem are compared. The three-dimensional problems of strip, rectangular, square and circular punches on a semi infinite metallic medium have been analyzed.

Abstract: With attention concentrated on the pole of bulge profile, tensile instability which results in the fracture of forward acting rupture discs has been studied. A formula was developed to calculate the theoretical limit pressure of rupture discs, and the theoretical predictions were compared with the measured data. It is found that the strain-hardening exponent of sheet metals has no influence on the limit pressure, whereas the limit pressure is in direct proportion to the strength coefficient of sheet metals. It is important to realize that the strength coefficient of sheet metals can be acquired easily from the limit pressure. This has potential value for the tests of mechanical properties of sheet metals.

Abstract: A piping system including straight pipes, elbows and tee branches in a nuclear power plant is mostly subjected to severe loading conditions with high temperature and pressure. In particular, the wall-thinning of an elbow due to flow accelerated corrosion is one of safety issues in the nuclear industry. In this respect, it is necessary to investigate the limit loads of an elbow with a wall-thinned part for evaluating integrity. In this paper, three dimensional plastic limit analyses are performed to obtain limit loads of an elbow with different bend angles as well as defect geometries under internal pressure and in-plane/out-of-plane bending moment. The limit loads are also compared with the results from limit load solutions of an uninjured elbow based on the von Mises yield criteria. Finally, the effects of significant factors, bend angle and defect shape, are quantified to estimate the exact load carrying capacity of an elbow during operation.