scholarly journals Thermoelasticity and ArUco marker-based model validation of polymer structure: application to the San Giorgio’s bridge inspection robot

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 177
Author(s):  
Lorenzo Capponi ◽  
Tommaso Tocci ◽  
Mariapaola D'Imperio ◽  
Syed Haider Jawad Abidi ◽  
Massimiliano Scaccia ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Numerical Models ◽  
Fiducial Markers ◽  
Stress Distributions ◽  
Bridge Inspection ◽  
Inspection Robot ◽  
Innovative Methodology ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Models Validation

<p>Experimental procedures are often involved in the numerical models validation. To define the behaviour of a structure, its underlying dynamics and stress distributions are generally investigated. In this research, a multi-instrumental and multi-spectral method is proposed in order to validate the numerical model of the Inspection Robot mounted on the new San Giorgio's Bridge on the Polcevera river. An infrared thermoelasticity-based approach is used to measure stress-concentration factors and, additionally, an innovative methodology is implemented to define the natural frequencies of the Robot Inspection structure, based on the detection of ArUco fiducial markers. Established impact hammer procedure is also performed for the validation of the results.</p>

Modeling the Influence of Microstructure on Stress Distributions and Concentrations in Pitting Corrosion

2018 ◽  
Author(s):  
Patrick Brewick ◽  
Andrew Geltmacher ◽  
Siddiq M. Qidwai
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Mechanical Load ◽  
High Strength ◽  
Geometrical Shape ◽  
Stress Distributions ◽  
Concentration Factors ◽  
Corrosion Pit ◽  
Stress Concentration Factors ◽  
Corrosion Pits

Despite the many advances made in material science, stainless steel and aluminum remain the structural materials best-suited for the naval fleet. While these metallic materials offer many benefits, such as high strength and good toughness, their persistent exposure to the maritime environment inevitably leads to issues with corrosion. Among the various manifestations of corrosion, pitting corrosion is of particular concern because the transition of corrosion pits to stress-corrosion cracks can lead to catastrophic failures. Traditional pitting corrosion analyses treat the pit shape as a semi-circle or ellipse and typically assume a growth pattern that maintains the original geometrical shape. However, when the underlying microstructure is incorporated into the model, pit growth is related to the grains surrounding the pit perimeter and the growth rate is proportional to crystallographic orientation. Since each grain has a potentially different orientation, pit growth happens at non-uniform rates leading to irregular geometries, i.e., non-circular and non-elliptical. These irregular pit geometries can further lead to higher stresses. This work presents a detailed look at corrosion pit growth coupled with mechanical load through a numerical model of a two-dimensional stable corrosion pit. Real microstructural information from a sample of 316 stainless steel is incorporated into the model to analyze microstructural effects on pit growth. Through this work, stress distributions and stress concentration factors are examined for a variety of pit geometries, including comparisons of their range of values to a typical, semi-circular pit. The consequences of these stress distributions and concentration factors are discussed.

Strengthening of Circular Holes in Plates Under Edge Loads

1944 ◽  
Vol 11 (3) ◽  
pp. A140-A148
Author(s):  
Leon Beskin
Keyword(s):  
Stress Concentration ◽  
Critical Stress ◽  
Hydrostatic Stress ◽  
Axial Stress ◽  
Theory Of Elasticity ◽  
Stress Distributions ◽  
Common Basis ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract In this paper, stress distributions are determined around strengthened circular holes in plates submitted to edge loads at infinity. Various proportions of circular strengthenings are considered, and three conditions of applied edge loads are investigated; uniform hydrostatic stress, uniform shearing stress, uniform axial stress. Stress distributions are found by methods of theory of elasticity, and the results are given in the form of stress-concentration factors. In order to reduce the results to a common basis, the stress-concentration factors have been defined by the ratio of the critical stress, computed by the distortion-energy theory, to the critical stress at infinity, which is the critical stress in the plate without hole.

Stresses Around an Elliptical Hole in a Finite Plate Subjected to Axial Loading

1966 ◽  
Vol 33 (1) ◽  
pp. 192-195 ◽  
Author(s):  
A. J. Durelli ◽  
V. J. Parks ◽  
H. C. Feng
Keyword(s):  
Elliptical Hole ◽  
Axial Loading ◽  
Finite Width ◽  
Stress Distributions ◽  
Maximum Compressive Stress ◽  
Finite Plate ◽  
Wide Range ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Distribution Of Stresses

A photoelastic solution of the distribution of stresses around a centrally located elliptical hole in a plate of finite width subjected to uniform axial loading is presented in this paper. Stress distributions at the boundaries are given for a wide range of the parameters, and stress-concentration factors have been computed for the points of maximum tensile and of maximum compressive stress. Comparisons are made with available theoretical solutions. Some appreciable discrepancies are pointed out.

scholarly journals Measurements of bridges' vibration characteristics using a mobile phone

2015 ◽  
Vol 8 (5) ◽  
pp. 721-743 ◽  
Author(s):  
Z. M. C. Pravia ◽  
J. D. Braido
Keyword(s):  
Finite Element ◽  
Fourier Transform ◽  
Mobile Phone ◽  
Natural Frequencies ◽  
Numerical Models ◽  
Element Model ◽  
Concrete Bridges ◽  
Structural Behavior ◽  
Experimental Phase ◽  
Bridge Inspection

ABSTRACTThis research presents an alternative way to perform a bridge inspection, which considers the dynamics parameters from the structure. It shows an experimental phase with use of a mobile phone to extract the accelerations answers from two concrete bridges, from those records is feasible to obtain natural frequencies using the Fast Fourier Transform (FFT).Numerical models with uses finite element model (FEM) allow to determine the natural frequencies from the two concrete bridges and compare with the experimental phase of each one. The final results shows it's possible to use mobiles phones to extract vibration answers from concrete bridges and define the structural behavior of bridges from natural frequencies, this procedure could be used to evaluate bridges with lower costs.

Stress and Strength Analysis of Equal-Diameter Tees

1991 ◽  
Vol 113 (1) ◽  
pp. 55-63 ◽  
Author(s):  
J. Zhixiang ◽  
Z. Qingjiang ◽  
Z. Siding
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Maximum Stress ◽  
Elastic Stress ◽  
Stress Factors ◽  
Strength Analysis ◽  
Stress Distributions ◽  
Concentration Factors ◽  
Stress Concentration Factors

The elastic stress distribution of four models (β=Do/Di=1.07, 1.20, unreinforced and weld-reinforced) under five typical external loadings and the strength of six models (in addition to β=1.50) under internal pressure are investigated experimentally. The maximum stress factors are obtained. The influences of weld-reinforced structure on stress distribution and strength characteristics of tees are discussed. The finite-element predictions of unreinforced tees with β=1.07, 1.11, 1.15, 1.20 are carried out. The predicted stress distributions agree well with measured results. The relation between β and stress concentration factors under various loadings are obtained.

Stress Concentration Factors in Tubular K-Joints Under Combined Loadings

2010 ◽  
Author(s):  
Tuanhai Chen ◽  
Guoming Chen
Keyword(s):  
Stress Concentration ◽  
Boundary Conditions ◽  
Hot Spot ◽  
Offshore Platforms ◽  
Stress Distributions ◽  
Hot Spot Stress ◽  
Loading Effects ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Combined Loadings

A numerical method of stress concentration factors (SCFs) in tubular K-joints under combined loadings was proposed, and the loading effects on SCFs were investigated by using this method. Since it couldn’t present the state of stress concentration very well if the displacements were used as the boundary conditions, the load boundary conditions were selected to analyze the stress distribution of the tubular K-joints. In view of the disadvantages of the superposition of stress distributions from each uniaxial loading mode, an alternative method for the calculation of the hot spot stress under combined loadings was provided. In this method, three basic types of basic loadings namely, axial loading, in-plane and out-of-plane bending moments were applied to the tubular joints simultaneously by virtue of the submodeling technique in ANSYS system. Then the stress distributions along the intersection of tubular K-joints under combined loadings were developed directly, and the hot spot stresses were obtained through extrapolation. Finally, according to parametric study, the loading effects of ice thickness and drift direction on SCF distributions and values were studied through this method. The investigation provides the theoretical basis for determining SCF in tubular K-joints under different load cases in evaluating the ice-induced fatigue of offshore platforms, and has very important engineering application value.

Stresses in torispherical drumheads: A critical evaluation

1966 ◽  
Vol 1 (2) ◽  
pp. 89-101 ◽  
Author(s):  
H Fessler ◽  
P Stanley
Keyword(s):  
Stress Concentration ◽  
Empirical Equation ◽  
Elastic Stress ◽  
Critical Evaluation ◽  
Stress Distributions ◽  
Head Shape ◽  
Codes Of Practice ◽  
Analytical Work ◽  
Concentration Factors ◽  
Stress Concentration Factors

An empirical equation is used to compare the results of the authors' extensive photoelastic study with stress concentration factors and other forms of head shape factor obtained from independent experimental and analytical work and from some codes of practice. Important differences are shown between the stress distributions in a number of shallow, thin models and a prototype and some analytical solutions. The variations of elastic stress concentration factor with wall thickness and with knuckle radius obtained from the photoelastic work are compared with other versions. The simplifications implicit in the recommendations of codes of practice are outlined and some recommendations are made for further work.

The Stress Distribution in a Strip Loaded in Tension by Means of a Central Pin

1956 ◽  
Vol 23 (1) ◽  
pp. 85-90
Author(s):  
P. S. Theocaris
Keyword(s):  
Exact Solution ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Approximation Method ◽  
Infinite Length ◽  
Stress Distributions ◽  
Axial Hole ◽  
Optimum Diameter ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract It is the purpose of this paper to give an exact solution for the stress distribution resulting from loading a perforated strip in tension through a rigid pin filling the hole. The strip is regarded as of an infinite length and having a single axial hole. Stress distributions are found by an alternating approximation method and the stresses are tabulated in the form of stress-concentration factors for different values of diameter of the hole. The influence of size of the hole on the stress concentration in the strip is investigated and the optimum diameter of the hole is evaluated.

Determination of Stress Concentration Factors for Shallow and Sharp V-Notches Using a Hybrid Method

1993 ◽  
Vol 46 (11S) ◽  
pp. S129-S135 ◽  
Author(s):  
Jose´ L. F. Freire ◽  
Eduardo A. Carvalho ◽  
Marco A. M. Cavaco
Keyword(s):  
Stress State ◽  
Stress Concentration ◽  
Hybrid Method ◽  
Analytical Description ◽  
Stress Distributions ◽  
Concentration Factors ◽  
Stress Concentration Factors

Stress distributions near the root of shallow and sharp V-notches are determined through a hybrid method which associates the isochromatic photoelastic response with the analytical description of the stress state for the points studied.

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