An Efficient Computational Approach for a Large Opening in a Cylindrical Vessel

1986 ◽  
Vol 108 (4) ◽  
pp. 436-442 ◽  
Author(s):  
C. R. Steele ◽  
M. L. Steele ◽  
A. Khathlan
Keyword(s):  
Shallow Shell ◽  
Computer Calculation ◽  
Computational Approach ◽  
Cylindrical Vessel ◽  
Intersection Curve ◽  
High Harmonics ◽  
Large Opening ◽  
Shell Equations ◽  
Present Effort ◽  
Good Agreement

In our previous work, solutions of the shallow shell equations have provided the basis for efficient computer calculation for a reinforced opening in a cylindrical vessel. However, solutions are restricted to smaller nozzles and openings (d/D≤0.5). In the present effort, an approach for the large opening has been developed which retains computational efficiency and minimum user time. The total solution can be divided into “high” harmonics around the intersection curve, which are obtained from asymptotic analysis, and particular solutions and low harmonics of self-equilibrating loads, which are obtained as “cut” solutions. By this, the vessel is considered to be cut along the portion of the circumference inside the intersection curve. Appropriate discontinuities of stress and displacement on the cut provide the necessary solutions. Results for a rigid nozzle with external loadings show good agreement with the previous shallow shell calculations for d/D≤0.5 with a substantial divergence for larger values of d/D. The behavior at the limit of d/D = 1 remains to be clarified.

Pressurized Cylindrical Shell With a Rigid Circular Inclusion

1978 ◽  
Vol 100 (2) ◽  
pp. 158-163 ◽  
Author(s):  
D. H. Bonde ◽  
K. P. Rao
Keyword(s):  
Differential Equation ◽  
Cylindrical Shell ◽  
Shallow Shell ◽  
Circular Inclusion ◽  
Hankel Functions ◽  
Curvature Parameter ◽  
Shell Equations ◽  
Limiting Case ◽  
Rigid Circular Inclusion ◽  
Good Agreement

The effect of a rigid circular inclusion on stresses in a cylindrical shell subjected to internal pressure has been studied. The two linear shallow shell equations governing the behavior of a cylindrical shell are converted into a single differential equation involving a curvature parameter and a potential function in nondimensionalized form. The solution in terms of Hankel functions is used to find membrane and bending stressses. Boundary conditions at the inclusion shell junction are expressed in a simple form involving the in-plane strains and change of curvature. Good agreement has been obtained for the limiting case of a flat plate. The shell results are plotted in nondimensional form for ready use.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

Computational Approach of the Cortical Bone Mechanical Behavior Based on an Elastic Viscoplastic Damageable Constitutive Model

2020 ◽  
Vol 12 (07) ◽  
pp. 2050081
Author(s):  
Tesnim Kraiem ◽  
Abdelwahed Barkaoui ◽  
Tarek Merzouki ◽  
Moez Chafra
Keyword(s):  
Mechanical Behavior ◽  
Bone Quality ◽  
Damage Evolution ◽  
Sensitivity Study ◽  
Computational Approach ◽  
Material Behavior ◽  
The Finite Element Method ◽  
Non Invasive ◽  
Applied Loading ◽  
Good Agreement

Bone mechanical behavior varies according to the mechanical loading to which it is subjected, and its response effectiveness mainly depends on its quality. Thus, measuring the indicators controlling the bone quality is required to assess its strength. Indeed, the Finite Element Method (FEM) provides a non-invasive tool to interpret bone quality. Therefore, this work coupled the FEM with a micromechanical law, aiming to provide an exhaustive description of the human bone mechanical behavior. Anisotropy, viscoplasticity and damage were introduced in the material behavior law and the damage evolution was plotted based on the applied loading. Then a sensitivity study was conducted to evaluate the effects of viscoplasticity and damage parameters on bone behavior. The obtained numerical results were in a good agreement with the previously reported experimental data and allowed to distinguish key parameters from non-significant ones. This new computational model provided a better understanding of the main parameters affecting bone behavior.

scholarly journals On shallow shell equations

2009 ◽  
Vol 2 (3) ◽  
pp. 697-722 ◽  
Author(s):  
Peng-Fei Yao ◽  
Keyword(s):  
Shallow Shell ◽  
Shell Equations

Stresses and Displacements in Vessels due to Loads Imposed by Single and Multiple Piping Attachments

1985 ◽  
Vol 107 (1) ◽  
pp. 51-59
Author(s):  
F. M. G. Wong ◽  
W. J. Craft ◽  
G. H. East
Keyword(s):  
Experimental Tests ◽  
Pressure Vessels ◽  
Numerical Convergence ◽  
Local Loads ◽  
Load Carrying ◽  
Convergence Problems ◽  
Shell Equations ◽  
Circular Functions ◽  
Simply Connected ◽  
Good Agreement

The Fourier solution for thin shell equations models pressure vessels as continuous simply connected surfaces with local loads. The technique allows placement of tractions with combinations of radial, shear, and axial components. Unlike Bijlaard, the solution in this paper includes loads placed at any position along the cylinder. Stiffness and the enhanced load-carrying capacity that internal pressure gives to thin vessels can be simulated. Numerical convergence problems are reduced by an improved displacement-load algorithm, and by use of load sites that allow the circular functions to be compactly grouped. A variety of loading distributions may be analyzed including large and small nozzles near and away from centerlines. Both rectangular and circular attachments are simulated. Through superposition, multiple attachments with their own loads may be examined. The attachments to the vessel may be either rigid or soft. A comparison to analytical results from Bijlaard shows excellent agreement. Comparisons with experimental tests on an API-650 nozzle on a storage tank are in good agreement. Variations between experimental and calculated results are primarily caused by assuming a simply supported base in the calculation, whereas in the experimental test, the base is more nearly fixed.

Analysis on Elastoplastic Stress Distribution in a Layered Cylindrical Vessel With Interlayer Gaps

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Shugen Xu ◽  
Weiqiang Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Distribution ◽  
Elastic Stress ◽  
Cylindrical Vessel ◽  
Elastoplastic Model ◽  
Elastoplastic Stress ◽  
Calculation Results ◽  
Von Mises ◽  
Good Agreement

In this paper, the formulae for elastoplastic stress distribution in layered cylindrical vessel layers with gaps have been provided. These formulae are based on the modified Pimshtein formulae for the elastic stress of layers. Plane strain with ideal elastoplastic model of materials is adopted. A practice example is presented to show how the formulae can be used for elastoplastic stress calculation. The hoop, radial, axial, and Von Mises equivalent stresses are obtained. The calculation result showed that the stress state of layered cylindrical vessel is more complex than that of monobloc cylindrical shell due to the interlayer gaps. The stress distribution is discontinuous. Calculation results obtained theoretically were compared to those obtained by finite element method (FEM). It shows that the results from the proposed formulae are in good agreement with finite element results.

Annular Dome Subjected to Uniform Load Over an Eccentric Circular Area

1978 ◽  
Vol 45 (4) ◽  
pp. 845-851
Author(s):  
H. Ainso
Keyword(s):  
General Solution ◽  
Shallow Shell ◽  
Outer Boundary ◽  
Uniform Load ◽  
Circular Area ◽  
Distributed Load ◽  
Load Effects ◽  
Particular Solution ◽  
Shell Equations ◽  
General Method

A general method is presented for solving shallow shell problems with finite boundaries and with an arbitrarily placed load that is uniformly distributed over a circular area of radius r0. A known solution for the distributed load on an unbounded shell is used to describe the load effects, and this particular solution is combined with Reissner’s general solution of the shallow shell equations in such a manner that all the boundary conditions are satisfied. Numerical results have been obtained for a shallow shell, clamped at the outer boundary and having a circular polar aperture free of tractions and support.

Numerical Simulation of Blast Loadings on a Thick-Walled Cylindrical Vessel

2007 ◽  
Author(s):  
Guide Deng ◽  
Ping Xu ◽  
Jinyang Zheng ◽  
Yongjun Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Dynamic Response ◽  
Rigid Wall ◽  
Cylindrical Vessel ◽  
Finite Element Code ◽  
Explicit Finite Element ◽  
Shell Deformation ◽  
Blast Loadings ◽  
Good Agreement

Determining blast loadings on an explosion containment vessel (ECV) is the foundation to design the ECV. Explosion of TNT centrally located in a thick-walled cylindrical vessel and its impact on the cylinder was simulated using the explicit finite element code LS-DYNA. Blast loadings on the cylinder computed are in good agreement with the corresponding experimental results. Then wall thickness and yield stress of the cylinder were changed in the following simulation to investigate effect of shell deformation on blast loadings. It is revealed that shell deformation during the primary pulses of blast loadings is so slight that it has little influence on the blast loadings. Though the deformation may increase greatly after the primary pulses, the dynamic response of an ECV is mainly affected by the primary pulses. Therefore, decoupled analyses are appropriate, in which the shell of an ECV is treated as a rigid wall when determining blast loadings on it.

Sign in / Sign up

Export Citation Format

Share Document