Extrapolation of Strain and Stress From Holographically Measured Surface Displacement

1979 ◽  
Vol 46 (3) ◽  
pp. 581-586 ◽  
Author(s):  
R. Da¨ndliker
Keyword(s):  
Stress Field ◽  
Boundary Conditions ◽  
Internal Pressure ◽  
Input Data ◽  
Cylindrical Tube ◽  
Surface Displacement ◽  
Volume Element ◽  
Extrapolation Method ◽  
Linear Extrapolation ◽  
Elastic Materials

For isotropic elastic materials, following Hooke’s law, the strain and stress field below the surface is uniquely determined by the knowledge of the displacement of the surface itself. From the holographically measured surface displacement u and the boundary conditions for the surface-stresses one can determine all 9 components of the vector-gradient grad u, which describes the strains as well as the tilt and the rotation of a volume element adjacent to the surface. It is shown that strain and stress can be uniquely calculated in a cone-shaped zone below the observed part of the surface by stepwise linear extrapolation. The depth of this cone depends on the density of the sample points and on the accuracy of the displacement measurement on the surface, as well as on the required accuracy of the extrapolated strain and stress values. The suggested extrapolation method has been tested numerically for a thick-walled cylindrical tube under internal pressure using simulated input data. The limitations and the accuracy are discussed.

scholarly journals Strain Growth in a Finite-Length Cylindrical Shell Under Internal Pressure Pulse

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Qi Dong ◽  
Q. M. Li ◽  
Jinyang Zheng
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Internal Pressure ◽  
Finite Length ◽  
Pressure Pulse ◽  
Elastic Response ◽  
Local Dynamic ◽  
Growth Phenomenon ◽  
Modal Coupling ◽  
Elastic Responses

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the earlier stage. In order to understand the possible mechanisms of the strain growth phenomenon in a cylindrical vessel, dynamic elastic responses of a finite-length cylindrical shell with different boundary conditions subjected to internal pressure pulse are studied by finite-element simulation using LS-DYNA. It is found that the strain growth in a finite-length cylindrical shell with sliding–sliding boundary conditions is caused by nonlinear modal coupling. Strain growth in a finite-length cylindrical shell with free–free or simply supported boundary conditions is primarily caused by the linear modal superposition, possibly enhanced by the nonlinear modal coupling. The understanding of these strain growth mechanisms can guide the design of cylindrical containment vessels.

Linear Static, Real-Time Finite Element Computations Based on Element Masks

2011 ◽  
Author(s):  
Holger Graf ◽  
Andre´ Stork
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Boundary Conditions ◽  
Real Time ◽  
Stiffness Matrix ◽  
New Method ◽  
Stress Distributions ◽  
Post Processing ◽  
Time Performance ◽  
Computational Overhead

This paper presents a new method for the manipulation of a given CAE domain in view of VR based explorations that enables engineers to interactively inspect and analyze a linear static domain. The interactions can ideally be performed in real-time in order to provide an intuitive impression of the changes to the underlying volumetric domain. We take the approach of element masking, i.e. the blending out of computations resulting from computational overhead for inner nodes, based on the inversion of the stiffness matrix. This allows us to optimize the re-simulation loop and to achieve real-time performance for strain and stress distributions with immediate visualization feedback caused by interactively changing boundary conditions. The novelty of the presented approach is a direct coupling of view dependent simulations and its close linkage to post-processing tasks. This allows engineers to also inspect the changes of the stress field inside of the volume during, e.g. cross sectioning.

scholarly journals A Novel Approach to Discrete Representative Volume Element Automation and Generation-DRAGen

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1887 ◽  
Author(s):  
Manuel Henrich ◽  
Felix Pütz ◽  
Sebastian Münstermann
Keyword(s):  
Input Data ◽  
Volume Element ◽  
Data Sets ◽  
Rsa Algorithm ◽  
Representative Volume ◽  
Novel Approach ◽  
Random Sequential Addition ◽  
Sequential Addition ◽  
Discrete Methods ◽  
Synthetic Microstructures

In this study, a novel approach for generating Representative Volume Elements (RVEs) is introduced. In contrast to common generators, the new RVE generator is based on discrete methods to reconstruct synthetic microstructures, using simple methods and a modular structure. The plain and uncomplicated structure of the generator makes the extension with new features quite simple. It is discussed why certain features are essential for microstructural simulations. The discrete methods are implemented into a python tool. A Random Sequential Addition (RSA)-Algorithm for discrete volumes is developed and the tessellation is realized with a discrete tessellation function. The results show that the generator can successfully reconstruct realistic microstructures with elongated grains and martensite bands from given input data sets.

Finite Axisymmetric Deformations of Initially Cylindrical Reinforced Membranes

1972 ◽  
Vol 45 (6) ◽  
pp. 1677-1683 ◽  
Author(s):  
A. D. Kydoniefs
Keyword(s):  
Stress Field ◽  
Internal Pressure ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Incompressible Material ◽  
Parameter System ◽  
Axial Section ◽  
Variable Pitch ◽  
Two Parameter

Abstract We consider the axisymmetrie deformations of an initially cylindrical membrane composed of an elastic, homogeneous, isotropic and incompressible material reinforced with a two-parameter system of perfectly flexible and inextensible helicoidal cords of variable pitch. The undeformed configuration is determined so that the deformed membrane has a given axial section under specified internal pressure. The corresponding stress field and cord tensions are obtained. The solution given is exact and valid for the general form of the strain—energy function.

Sign in / Sign up

Export Citation Format

Share Document