scholarly journals Effect of material properties on optimal radial strain gage locations in sharp V-notched configurations

2018 ◽  
Vol 172 ◽  
pp. 03002 ◽  
Author(s):  
Pranjol Paul ◽  
K.S.R. Krishna Murthy ◽  
Debabrata Chakraborty
Keyword(s):  
Strain Gage ◽  
Material Properties ◽  
A Priori ◽  
Radial Strain ◽  
Numerical Approach ◽  
Conference Paper ◽  
Notch Angle ◽  
Notch Stress ◽  
Notch Length

A simple yet reliable and powerful methodology using only one strain gage has been recommended for appropriate determination of notch stress intensity factor (NSIF) for sharp V-notched configurations subjected to mode I condition. The methodology is supported by strong theoretical postulates, and it permits the gage to be pasted prominently apart from tip of the notch thus avoiding various problems associated with singularities. Unlike the conventional methodologies, the recommended strain gage methodology also proposes optimal radial strain gage locations which are beneficial in appropriate determination of NSIFs. A FEM based numerical approach is adopted for obtaining optimal radial gage locations a priori for the aforesaid configuration. The optimal radial gage locations are observed to be influenced by parameters viz. the notch angle, the ratio of notch length to width of the plate and also material properties. Results were already published by the authors to establish that the optimal radial gage locations are influenced by the notch angle and the ratio of notch length to width of the plate. In this conference paper, a case is studied with a completely different material to check whether material properties influence the graphical trends of results or not.

Determination of Charge Coefficient of Piezoelectric Films Using a Combined Finite Element Model and Dynamic Loading Technique

2020 ◽  
Vol 835 ◽  
pp. 229-242
Author(s):  
Oboso P. Bernard ◽  
Nagih M. Shaalan ◽  
Mohab Hossam ◽  
Mohsen A. Hassan
Keyword(s):  
Finite Element ◽  
Dynamic Loading ◽  
Material Properties ◽  
Accurate Determination ◽  
Substrate Material ◽  
Experimental Results ◽  
Piezoelectric Composite ◽  
Piezoelectric Film ◽  
Piezoelectric Charge

Accurate determination of piezoelectric properties such as piezoelectric charge coefficients (d33) is an essential step in the design process of sensors and actuators using piezoelectric effect. In this study, a cost-effective and accurate method based on dynamic loading technique was proposed to determine the piezoelectric charge coefficient d33. Finite element analysis (FEA) model was developed in order to estimate d33 and validate the obtained values with experimental results. The experiment was conducted on a piezoelectric disc with a known d33 value. The effect of measuring boundary conditions, substrate material properties and specimen geometry on measured d33 value were conducted. The experimental results reveal that the determined d33 coefficient by this technique is accurate as it falls within the manufactures tolerance specifications of PZT-5A piezoelectric film d33. Further, obtained simulation results on fibre reinforced and particle reinforced piezoelectric composite were found to be similar to those that have been obtained using more advanced techniques. FE-results showed that the measured d33 coefficients depend on measuring boundary condition, piezoelectric film thickness, and substrate material properties. This method was proved to be suitable for determination of d33 coefficient effectively for piezoelectric samples of any arbitrary geometry without compromising on the accuracy of measured d33.

Determination of multidirectional myocardial deformations in cats with hypertrophic cardiomyopathy by using two-dimensional speckle-tracking echocardiography

2017 ◽  
Vol 19 (12) ◽  
pp. 1283-1289 ◽  
Author(s):  
Ryohei Suzuki ◽  
Yohei Mochizuki ◽  
Hiroki Yoshimatsu ◽  
Takahiro Teshima ◽  
Hirotaka Matsumoto ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Speckle Tracking ◽  
Speckle Tracking Echocardiography ◽  
Contractile Function ◽  
Radial Strain ◽  
Clinical Signs ◽  
Myocardial Deformation ◽  
Radial Deformation ◽  
Two Dimensional

Objectives Hypertrophic cardiomyopathy, a primary disorder of the myocardium, is the most common cardiac disease in cats. However, determination of myocardial deformation with two-dimensional speckle-tracking echocardiography in cats with various stages of hypertrophic cardiomyopathy has not yet been reported. This study was designed to measure quantitatively multidirectional myocardial deformations of cats with hypertrophic cardiomyopathy. Methods Thirty-two client-owned cats with hypertrophic cardiomyopathy and 14 healthy cats serving as controls were enrolled and underwent assessment of myocardial deformation (peak systolic strain and strain rate) in the longitudinal, radial and circumferential directions. Results Longitudinal and radial deformations were reduced in cats with hypertrophic cardiomyopathy, despite normal systolic function determined by conventional echocardiography. Cats with severely symptomatic hypertrophic cardiomyopathy also had lower peak systolic circumferential strain, in addition to longitudinal and radial strain. Conclusions and relevance Longitudinal and radial deformation may be helpful in the diagnosis of hypertrophic cardiomyopathy. Additionally, the lower circumferential deformation in cats with severe hypertrophic cardiomyopathy may contribute to clinical findings of decompensation, and seems to be related to severe cardiac clinical signs. Indices of multidirectional myocardial deformations by two-dimensional speckle-tracking echocardiography may be useful markers and help to distinguish between cats with hypertrophic cardiomyopathy and healthy cats. Additionally, they may provide more detailed assessment of contractile function in cats with hypertrophic cardiomyopathy.

THE PROBLEM OF IDENTIFICATION OF HYDRAULIC RESISTANCE COEFFICIENTS IN MAKISTRAL GAS PIPELINE

2021 ◽  
pp. 6-11
Author(s):  
G. Gasymov
Keyword(s):  
Hydraulic Resistance ◽  
Group Identification ◽  
Numerical Approach ◽  
Transportation Systems ◽  
Gas Pipeline ◽  
Closed Loops ◽  
Hydraulic Network ◽  
Resistance Coefficients ◽  
Operating Regimes

A numerical approach, based on obtaining design formulas for the determination of hydraulic resistance coefficients of sites in pipeline transportation systems in the presence of the results of observations over a gas pipeline operating regimes, is proposed. The representation of the hydraulic network in the form of a directed graph allows to essentially reduce the number of equations in the system down to the number of closed loops. In the software implementation of the method described, for the solution of practical problems, group identification of the hydraulic resistance coefficients is provided for every eventuality.

Détermination de la taille et du nombre d’échantillons devant être analysés en laboratoire pour la caractérisation statistique de la microstructure d’une roche argileuse

2020 ◽  
pp. 1
Author(s):  
Anne-Laure Fauchille ◽  
Bram van den Eijnden ◽  
Kevin Taylor ◽  
Peter David Lee
Keyword(s):  
Representative Volume Element ◽  
Numerical Approach ◽  
Volume Element ◽  
Méthode Statistique ◽  
Representative Volume ◽  
Microscopie Électronique ◽  
Random Composites ◽  
Sols Argileux ◽  
Microscopie Électronique À Balayage

À l’échelle du laboratoire, les roches argileuses sont des matériaux hétérogènes dont le comportement thermo-hydromécanique est en grande partie contrôlé par la microstructure. Le choix du nombre et de la taille des échantillons à étudier en laboratoire est déterminant pour appréhender la variabilité des propriétés de la roche argileuse à petite échelle. Cet article présente une méthode statistique permettant de préciser la surface (ou le volume) et le nombre d’échantillons à prendre en compte pour qu’une propriété p choisie caractérisant la microstructure, soit statistiquement représentative. Initialement établie dans un cas général par Kanit et al. (2003. Determination of the size of the representative volume element for random composites: statistical and numerical approach. Int J Solids Struct 40(13–14): 3647–3679), cette méthode consiste à partitionner un échantillon de propriété moyenne [see formula in PDF] connue, en sous-échantillons de surface D × D afin de calculer l’écart-type et l’erreur relative de la mesure de p en fonction de D. Cette méthode permet ainsi de définir des surfaces élémentaires représentatives de p en tenant compte de l’erreur relative par rapport à [see formula in PDF]. La méthode est d’abord présentée dans des cas généraux en 2D et 3D, et un exemple type est ensuite développé en 2D pour caractériser la fraction argileuse d’une lamine sédimentaire de Bowland (Royaume-Uni). La fraction surfacique argileuse est choisie comme propriété p, à partir d’une image grand-champ en microscopie électronique à balayage. La méthode est applicable en 2D et 3D sur les matériaux finement divisés autant sur les roches que sur les sols argileux, tant que l’échantillon considéré contient suffisamment d’éléments figurés (inclusions rigides ou pores dans une matrice par exemple) pour permettre l’utilisation des statistiques. L’apport principal visé pour la communauté des ingénieurs est dans la mesure du possible un meilleur ciblage de la quantité d’échantillons à prélever en forage pour mieux évaluer la variabilité des paramètres macroscopiques des roches argileuses. Les limites de la méthode sont ensuite discutées.

A least squares method for earthquake mechanism determination using S-wave data

1964 ◽  
Vol 54 (6A) ◽  
pp. 2037-2047
Author(s):  
Agustin Udias
Keyword(s):  
Least Squares ◽  
Statistical Evaluation ◽  
Least Squares Method ◽  
Numerical Approach ◽  
Focal Mechanisms ◽  
Least Square ◽  
S Wave ◽  
Double Couple ◽  
Earthquake Mechanism

abstract In this paper a numerical approach to the determination of focal mechanisms based on the observation of the polarization of the S wave at N stations is presented. Least-square methods are developed for the determination of the orientation of the single and double couple sources. The methods allow a statistical evaluation of the data and of the accuracy of the solutions.

Sign in / Sign up

Export Citation Format

Share Document