scholarly journals The Optimum Design of Stepped Shafts: A Study in Computational Optimization

1982 ◽  
Author(s):  
C. J. Maday
Keyword(s):  
Optimum Design ◽  
Critical Speed ◽  
Numerical Solutions ◽  
Boundary Value ◽  
Minimum Principle ◽  
Problem Formulation ◽  
Rayleigh Quotient ◽  
Computational Optimization ◽  
Stepped Shaft ◽  
Determine Step

Optimum stepped shaft designs are obtained through an application of Pontryagin’s Minimum Principle. Optimum designs are obtained for a given critical speed of specified order. Indexes of Performance to be minimized include mass and rotating inertia. A general problem formulation illustrates how constraints on stress, deflections, and geometric design are taken in account. Numerical solutions are obtained to nonlinear multi-point-boundary-value-problems. A Newton-Raphson algorithm was developed to determine step locations precisely in order to facilitate the convergence of the shooting method used to solve the boundary value problem. Numerical solutions are determined with an assumed critical speed; a Rayleigh quotient calculation is used to verify that the optimum design possesses the assumed value.

A Class of Minimum Weight Shafts

1974 ◽  
Vol 96 (1) ◽  
pp. 166-170 ◽  
Author(s):  
C. J. Maday
Keyword(s):  
Boundary Value Problem ◽  
Critical Speed ◽  
Minimum Weight ◽  
Boundary Value ◽  
Minimum Principle ◽  
Light Weight ◽  
Point Boundary ◽  
Simply Supported ◽  
Set Up

Light weight shafts reduce bearing forces and allow the use of smaller bearings, seals, and supports. The Minimum Principle is used to set up the problem of determining the minimum weight shaft for a specified critical speed of given order. Specific examples include simply supported shafts and cantilevered shafts with and without a disk. The designs are obtained from the solution to a nonlinear multi-point boundary-value-problem. Minimum weight configurations represent a standard against which other designs, such as stepped shafts, can be compared.

Estimating Critical Speeds of Stepped Shafts with Flexible Bearings

1971 ◽  
Vol 8 (03) ◽  
pp. 327-333
Author(s):  
R. H. Salzman
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Design Stage ◽  
Normal Range ◽  
Critical Speeds ◽  
Stepped Shaft ◽  
Bearing Stiffness ◽  
Variable Support ◽  
Method Show ◽  
Good Agreement

This paper presents a semi-graphical approach for finding the first critical speed of a stepped shaft with finite bearing stiffness. The method is particularly applicable to high-speed turbine rotors with journal bearings. Using Rayleigh's Method and the exact solution for whirling of a uniform shaft with variable support stiffness, estimates of the lowest critical speed are easily obtained which are useful in the design stage. First critical speeds determined by this method show good agreement with values computed by the Prohl Method for the normal range of bearing stiffness. A criterion is also established for determining if the criticals are "bearing critical speeds" or "bending critical speeds," which is of importance in design. Discusser E. G. Baker

scholarly journals Constitutive Relation for Large Deformations of Fiber-Reinforced Rubberlike Materials with Different Response in Tension and Compression

2016 ◽  
Vol 44 (1) ◽  
pp. 51-72 ◽  
Author(s):  
Qian Li ◽  
David A. Dillard ◽  
Romesh C. Batra
Keyword(s):  
Constitutive Relation ◽  
Large Deformations ◽  
Numerical Solutions ◽  
Boundary Value ◽  
Strain Tensor ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Tension And Compression ◽  
Different Response ◽  
Rubberlike Materials

ABSTRACT Fiber-reinforced rubberlike materials commonly used in tires undergo large deformations and exhibit different responses in tension and compression along the fiber direction. Assuming that the response of a fiber-reinforced rubberlike material can be modeled as transversely isotropic with the fiber direction as the axis of transverse isotropy, we express the stored energy function in terms of the five invariants of the right Cauchy-Green strain tensor and account for different response in tension and compression along the fiber direction. The constitutive relation accounts for both material and geometric nonlinearities and incorporates effects of the fifth strain invariant, I5. It has been shown by Merodio and Ogden that in shear dominated deformations, I5 makes a significant contribution to the stress-strain curve. We have implemented the proposed constitutive relation in the commercial software, LS-DYNA. The numerical solutions of a few boundary value problems studied here agree with their analytical solutions derived by using Ericksen's inverse approach, in which part of the solution is assumed and unknowns in the presumed solution are found by analyzing the pertinent boundary value problem. However, computed results have not been compared with experimental findings. When test data become available, one can modify the form of the strain energy density and replace the proposed constitutive relation by the new one in LS-DYNA.

Numerical Solutions of Boundary Value Problems with So-Called Shooting Method

2021 ◽  
Author(s):  
Sujaul Chowdhury ◽  
Mubin Md. Al Furkan ◽  
Nazmus Sayadat Ifat
Keyword(s):  
Boundary Value Problems ◽  
Shooting Method ◽  
Numerical Solutions ◽  
Boundary Value

scholarly journals Nature Inspired Computational Technique for the Numerical Solution of Nonlinear Singular Boundary Value Problems Arising in Physiology

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Suheel Abdullah Malik ◽  
Ijaz Mansoor Qureshi ◽  
Muhammad Amir ◽  
Ihsanul Haq
Keyword(s):  
Numerical Solution ◽  
Boundary Value Problems ◽  
Numerical Solutions ◽  
Fitness Function ◽  
Boundary Value ◽  
Computational Technique ◽  
Singular Boundary ◽  
Interior Point Algorithm ◽  
Singular Boundary Value Problems ◽  
Hybrid Heuristic

We present a hybrid heuristic computing method for the numerical solution of nonlinear singular boundary value problems arising in physiology. The approximate solution is deduced as a linear combination of some log sigmoid basis functions. A fitness function representing the sum of the mean square error of the given nonlinear ordinary differential equation (ODE) and its boundary conditions is formulated. The optimization of the unknown adjustable parameters contained in the fitness function is performed by the hybrid heuristic computation algorithm based on genetic algorithm (GA), interior point algorithm (IPA), and active set algorithm (ASA). The efficiency and the viability of the proposed method are confirmed by solving three examples from physiology. The obtained approximate solutions are found in excellent agreement with the exact solutions as well as some conventional numerical solutions.

Sign in / Sign up

Export Citation Format

Share Document