Material Identification On Thin Shells Using the Virtual Fields Method, Demonstrated On the Human Eardrum

2021 ◽  
Author(s):  
Felipe Pires ◽  
Stephane Avril ◽  
Pieter Livens ◽  
Julio A. Cordioli ◽  
Joris Dirckx
Keyword(s):  
Experimental Data ◽  
Outer Surface ◽  
Plate Theory ◽  
Measurement Data ◽  
Total Strain ◽  
Virtual Fields Method ◽  
Material Parameters ◽  
Membrane Strain

Abstract Characterization of material parameters from experimental data remains challenging, especially on biological structures. One of such techniques allowing for the inverse determination of material parameters from measurement data is the Virtual Fields Method (VFM). However, application of the VFM on general structures of complicated shape has not yet been extensively investigated. In this paper, we extend the framework of the VFM method to thin curved solids in 3D, commonly denoted shells. Our method is then used to estimate theYoung's modulus and hysteretic damping of the human eardrum. By utilizing Kirchhoff plate theory, we assume that the behavior of the shell varies linearly through the thickness. The total strain of the shell can then be separated in a bending and membrane strain. This in turn allowed for an application of the VFM based only on data of the outer surface of the shell. We validated our method on simulated and experimental data of a human eardrum made to vibrate at certain frequencies. It was shown that the identified material properties were accurately determined based only on data from the outer surface and are in agreement with literature. Additionally, we observed that neither the bending nor the membrane strain in an human eardrum can be neglected and both contribute significantly to the total strain found experimentally.

Mechanical, Electrical and Thermal Characterization of Commercially Available LTCC Dielectric Tapes

2013 ◽  
Vol 543 ◽  
pp. 212-215
Author(s):  
Goran Radosavljević ◽  
Nelu Blaž ◽  
Andrea Marić ◽  
W. Smetana ◽  
Ljiljana Živanov
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Electrical Properties ◽  
Material Characterization ◽  
Mechanical Characterization ◽  
Thermal Characterization ◽  
Material Parameters ◽  
Mechanical And Electrical Properties

Presented paper deals with mechanical and electrical properties of several commercially available LTCC (Low Temperature Co-fired Technology) tapes, as well as their thermal characterization. Three commercially available dielectric tape materials provided by Heraeus (CT700, CT707 and CT800) are investigated. The samples for determination of significant material parameters are prepared using the standard LTCC fabrication process. Results of the material characterization (chemical analysis, surface roughness electrical and mechanical properties) are presented. In addition thermo-electrical and-mechanical characterization of investigated tapes analysis is performed.

Manufactured Part Modeling for Characterization of Geometric Variations of Automotive Spaceframe Extrusions

1998 ◽  
Vol 120 (3) ◽  
pp. 523-531 ◽  
Author(s):  
Yu (Michael) Wang ◽  
S. Gupta ◽  
F. L. Hulting ◽  
P. S. Fussell
Keyword(s):  
Experimental Data ◽  
Measurement Data ◽  
Critical Parameters ◽  
Coordinate Measurement ◽  
Coordinate Measurement Machine ◽  
Bending Process ◽  
Actual Shape ◽  
Part Modeling ◽  
Part Model

This article presents a method for characterizing geometric shape variations in manufactured automotive spaceframe extrusions using measurement data obtained by a Coordinate Measurement Machine (CMM). With a manufacturing perspective, a modeling scheme is proposed for representing the actual shape of the extrusions. Systematic deviations in the geometry of the parts from their theoretically perfect design description models are described by the critical parameters of their manufactured part models (MPMs), which are constructed by fitting CMM data through an optimization. The manufactured part model can then be interpreted in a meaningful way for improving bending process as well as quantifying the process capability. An application of the methodology is illustrated through the analysis of experimental data for rotary draw bent extrusions used in the aluminum intensive automobiles.

Complex Permeability Measurements of Microwave Ferrites1

1996 ◽  
Vol 430 ◽  
Author(s):  
Richard G. Geyer ◽  
Jerzy Krupka
Keyword(s):  
Saturation Magnetization ◽  
Measurement Data ◽  
Accurate Method ◽  
Ring Resonators ◽  
Complex Permeability ◽  
Microwave Frequencies ◽  
The Real ◽  
Theoretical Predictions

AbstractA rigorous and accurate method for the experimental determination of the complex permeability of demagnetized ferrites at microwave frequencies is presented. The measurement uses low- loss dielectric ring resonators, is nondestructive, and allows complex permeability characterization of a single ferrite sample to be performed at frequencies from 2 GHz to 25 GHz. A wide variety of ceramic microwave ferrites having various compositions and differing saturation magnetizations were measured in the demagnetized state. Generally, at any frequency greater than gyromagnetic resonance, the real part of the complex permeability increases as saturation magnetization increases.For the same frequency magnetic losses increases as saturation magnetization increases. The real permeability results are compared with magnetostatic theoretical predictions. Measurement data show excellent agreement with theoretical predictions, but only when 2πγMs/ω < 0.75, where γ is the gyromagnetic ratio, Ms is saturation magnetization, and ω is the radian rf frequency.

A Method for Ultrasonic Characterization of Density, Thickness and Velocity of Homogeneous Coating

2011 ◽  
Vol 675-677 ◽  
pp. 1217-1220 ◽  
Author(s):  
Y. Zhao ◽  
Zhen Yue Ma ◽  
Li Lin ◽  
X.M. Li ◽  
M.K. Lei
Keyword(s):  
Experimental Data ◽  
Amplitude Spectrum ◽  
Reference Value ◽  
Nondestructive Method ◽  
Inverse Algorithm ◽  
Ultrasonic Characterization ◽  
Ultrasonic Reflection Coefficient ◽  
Relative Errors

This paper provides a nondestructive method for determination of the density, thickness and velocity of homogeneous coating from an inversion of experimental ultrasonic reflection coefficient amplitude spectrum (URCAS). The detailed analyses of the inverse algorithm and sensitivity of URCAS to the density, thickness and velocity are presented, and the sensitivity is identified as a basis for selecting the experimental data used in inversion. An example of the method and experimental measurement for comparison was given for an epoxy coating with the thickness of 0.277 mm. The relative errors between the inversion and reference value of the density, thickness and velocity were found to be 0.5 %, 3.97 %, and 0.97 %, respectively.

scholarly journals An Investigation of Uniaxial Mechanical Properties of Excised Sheep Heart Muscle Fibre – Fitting of Different Hyperelastic Constitutive Models

2021 ◽  
Author(s):  
Fulufhelo Nemavhola ◽  
Harry M Ngwangwa ◽  
Thanyani Pandelani
Keyword(s):  
Experimental Data ◽  
Soft Tissues ◽  
Constitutive Models ◽  
Finite Element Models ◽  
Predictive Capability ◽  
Material Parameters ◽  
Linear Finite Element ◽  
Fitting Algorithm ◽  
Testing Data

Abstract : This paper presents the investigation of biomechanical behaviour of sheep heart fibre using uniaxial tests in various samples. Non-linear Finite Element models (FEA) that are utilised in understanding mechanisms of different diseases may not be developed without the accurate material properties. This paper presents uniaxial mechanical testing data of the sheep heart fibre. The mechanical uniaxial data of the heart fibre was then used in fitting four constitutive models including the Fung model, Polynomial (Anisotropic), Holzapfel (2005) model, Holzapfel (2000) model and the Four-fibre Family model. Even though the constitutive models for soft tissues including heart myocardium have been presented over several decades, there is still a need for accurate material parameters from reliable hyperelastic constitutive models. Therefore, the aim of this research paper is to select five hyperelastic constitutive models and fit experimental data in the uniaxial experimental data of the sheep heart fibre. A fitting algorithm was made used to optimally fitting and determination of the material parameters based on selected hyperelastic constitutive model. In this study, the evaluation index (EI) was used to measure the performance and capability of each selected anisotropic hyperelatic model. It was observed that the best predictive capability of the mechanical behaviour of sheep heart fibre the Polynomial (anisotropic) model has the EI of 100 and this means that it is the best performance when compared to all the other models.

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