Finite elements in the analysis of pressure vessels and piping, an addendum: A bibliography (2001–2004)

The ability to understand and manage the performance of hydraulic control valves is important in many automatic and manual industrial processes. The use of computational fluid dynamics (CFD) aids in the design of such valves by inexpensively providing insight into flow patterns, potential noise sources, and cavitation. Applications of CFD to study the performance of complex three-dimensional (3D) valves, such as poppet, spool, and butterfly valves, are becoming more common. Still, validation and accuracy remain an issue. The Reynolds-averaged Navier-Stokes equations were solved numerically using the commercial CFD package FLUENT V6.2 to assess the effect of geometry on the performance of a 3D control valve. The influence of the turbulence model and of a cavitation model was also investigated. Comparisons were made to experimental data when available. The 3D model of the valve was constructed by decomposing the valve into several subdomains. Agreement between the numerical predictions and measurements of flow pressure was less than 6% for all cases studied. Passive flow control, designed to minimize vortical structures at the piston exit and reduce potential cavitation, noise, and vibrations, was achieved by geometric smoothing. In addition, these changes helped to increase C υ and reduce the area affected by cavitation as it is related to the jet shape originated at the valve throat. The importance of accounting for full 3D geometry effects in modeling and optimizing control valve performance was demonstrated via CFD. This is particularly important in the vicinity of the piston. It is worth noting that the original geometry resulted in a lower C υ with higher velocity magnitude within the valve, whereas after smoothing C υ increased and served to delay cavitation inception.

Three-Dimensional Modeling and Geometrical Influence on the Hydraulic Performance of a Control Valve

A numerical study on the lateral indentation of continuously supported tubes

A closed-form solution for lateral indentation of pressurized pipes resting on a flexible bed

A Finite Element Approach to Reinforced Concrete Slab Design

Previous test results of two-way fully restrained reinforced concrete slabs are used to optimize the model parameter values involved in a finite element program. The parameters whose sensitivities control the simulation process are identified through extensive parametric studies using both the displacement and load control strategies, and values are identified for them. Use of such values has been shown to guarantee reliable predictions of both the peak load and the corresponding deflection of arbitrary fully restrained rectangular slabs. A series of numerical predictions of over 850 computer model slabs are undertaken, varying the geometric and material properties, as well as the reinforcement ratios. The result is used for developing charts that may be used for the strength and displacement determination of arbitrary fully restrained slabs. The charts are used for the predictions of 36 previously tested slabs, in which the slab strength is predicted to within a mean accuracy of 2%, and the deflection is predicted to within a mean accuracy of 4%. Other practical applications of reliable numerical predictions are discussed.

Optimized Design Charts for Fully Restrained Slabs by FE Predictions

Semi-empirical equations for pipeline design by the finite element method

The procedures involved in the use of a typical finite-element model for the development of prediction charts for partially clamped, reinforced concrete slabs, under uniformly distributed loading, are demonstrated in this paper. Test results from two sets of four partially clamped slabs are used as a basis for finite-element simulation and extensive parametric studies to identify the set of computational conditions and model parameter values, which would guarantee reliable prediction for similar slabs. The direct finite-element simulation of nine other partially clamped slabs, with the identified values, gave an average experiment-to-predicted strength ratio of 0.93. The developed finite-element model is then used for the analysis of a total of 450 computer-modeled, partially clamped slabs, resulting from various geometric dimensions, material strengths, and reinforcement ratios; and the resulting database of ultimate strengths is used for chart development. Predictions from the developed charts for partially clamped slabs of similar configuration are found to be of the same order of accuracy as the direct finite-element analysis. Other design applications of the outlined procedure are also discussed.

Development of Charts for Partially Clamped Slabs by Finite-Element Predictions

Accurate prediction of the ultimate capacity of engineering structures by numerical models depends on their abiity to account for the nonlinearities involved in the problem. The use of the finite-element method often requires considerable expertise which is not widely available in the design community. In this paper, 2 methods of developing simple prediction equations are outlined, based on results from finite-element parametric studies of representative structures. These are applied, respectively, to partially restrained reinforced concrete slabs and to steel pipes. A comparison with limited experimental data showed reasonable accuracy, thus suggesting that the methods could be used in a wider context.

Olubayo O. R. Famiyesin

Papers

Optimized Design Charts for Fully Restrained Slabs by FE Predictions

Semi-empirical equations for pipeline design by the finite element method

Development of Charts for Partially Clamped Slabs by Finite-Element Predictions

Post-finite-element prediction strategies for engineering structures