Comparative study of destructive, nondestructive, and numerical procedures for the determination of moisture dependent shear moduli in Scots pine wood

2021 ◽  
Vol 63 (11) ◽  
pp. 1063-1069
Author(s):  
Murat Aydın ◽  
Hasan Hüseyin Ciritcioğlu
Keyword(s):  
Finite Element ◽  
Relative Humidity ◽  
Shear Modulus ◽  
Scots Pine ◽  
Constant Temperature ◽  
Transverse Wave ◽  
Element Analysis ◽  
Shear Moduli ◽  
Principal Axes ◽  
Static Shear

Abstract In this study, moisture dependent shear moduli in Scots pine (Pinus sylvestris L.) wood were determined by a 45° off-axis (longitudinal, radial, and tangential) compression test and ultrasonic transverse wave propagation. Finite element modeling was performed to ascertain how the results agree with the numerical method. Ultrasonic transverse wave velocities on the LR, LT, and RT planes were decreased from 1347, 1323, and 589 m × s-1 to 1286, 1269, and 561 m × s-1 when relative humidity increased from 45 % to 85 % at a constant temperature of 20 ± 1 °C, respectively. The dynamic and static shear modulus on the LR, LT, and RT planes were decreased from 988, 953, and 189, and 966, 914, and 182 MPa to 927, 903, and 176, and 845, 784, and 154 MPa when relative humidity increased from 45 % to 85 % at a constant temperature of 20 ± 1 °C, respectively. Therefore, both velocity and modulus values at all principal axes and planes were decreased with an increase in moisture. Maximum (15.2 %) and minimum (2.3 %) differences between dynamic and the static shear modulus were observed for GLT at 85 % and GLR at 45 % relative humidity, respectively. Coefficients of determinations between the dynamic and static shear moduli were ranged from 0.68 (GLR at 65 % RH) to 0.97 (GLR at 85 % RH). Finite element analysis, only for 65 % RH values, was performed using Solid 45 element, and, according to results, load-deformation curves created by linear orthotropic material properties, are well-matched with the static curves.

scholarly journals Viscoelastic analysis of Calving Glaciers

1980 ◽  
Vol 1 ◽  
pp. 37-41 ◽  
Author(s):  
D. V. Reddy ◽  
W. Bobby ◽  
M. Arockiasamy ◽  
R. T. Dempster
Keyword(s):  
Finite Element ◽  
Sea Water ◽  
Water Pressure ◽  
Computer Code ◽  
Ice Shelf ◽  
Element Analysis ◽  
Ice Shelves ◽  
Shear Moduli ◽  
Relaxation Functions ◽  
Spring Force

Calving of floating ice shelves is studied by a viscoelastic finite-element analysis. The fan-shaped breaking-up of glaciers due to forces that cause bending on creeping ice is assumed to be axisymmetric. Bending may be due to geometry of the bcdrock, action of tides and waves, and imbalance (at the ice front) between the stress in the ice and the sea-water pressure.The bulk and shear moduli of the ice are represented by relaxation functions of the Prony series, which is a discrete relaxation spectrum composed of a constant and a summation of exponential terms. These properties are also functions of temperature, that varies over the thickness of the ice shelf. The temperature distribution across the thickness of the ice is obtained from calculations based on a linear dependence of thermal conductivity on the temperature. Numerical results are presented for various calving mechanisms. A computer code, VISIC1, is developed by modifying a finite-element viscoelastic code, VISICE, for floating ice islands. The buoyancy of the water is taken into account by a Winkler spring model, with the spring force determined from displaced volume. Locations of crack initiation obtained from the analysis are used to predict the iceberg size immediately after calving.

Finite Element Analysis of a Simply Supported MR Fluid Sandwich Beam Based on ANSYS

2011 ◽  
Vol 94-96 ◽  
pp. 902-908 ◽  
Author(s):  
Zheng Xin Zhang ◽  
Fang Lin Huang ◽  
Yan Bin Wu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Modulus ◽  
Sandwich Beam ◽  
Main Idea ◽  
Magnetorheological Fluid ◽  
Element Analysis ◽  
Simply Supported ◽  
Mr Dampers ◽  
Element Type

This paper presents a method to simulate the mechanical behavior of magnetorheological fluid (MRF) subjected to magnetic field in the pre-yield region in ANSYS. The main idea is to devide an MRF element into two coincident elements, one of them has density and viscosity without shear modulus while another has shear modulus without density and viscosity. Taking a simply supported MRF sandwich beam as an example, good results and reasonable conclusion are obtained by comparing the results with the theoretical analysis and experimental study of Ref.[1]. The validity of finite element analysis is also investigated in this paper. At present, there is no exactly appropriate element type in ANSYS to model MRF, this kind of method called coincident elements method (CEM) will provide a new way to model the structures with MRF or MR dampers in ANSYS, and it also has reference roles for the future development of related elements in ANSYS.

Evaluation of Transverse Shear Moduli of Composite Sandwich Beams Through Three-Point Bending Tests

2018 ◽  
Author(s):  
Özgün Şener ◽  
Oğuzhan Dede ◽  
Oğuz Atalay ◽  
Mert Atasoy ◽  
Altan Kayran
Keyword(s):  
Finite Element ◽  
Transverse Shear ◽  
Sandwich Beam ◽  
Image Correlation ◽  
Core Material ◽  
Flexural Stiffness ◽  
Element Analysis ◽  
Bending Tests ◽  
Shear Moduli ◽  
Composite Sandwich

Transverse shear moduli of the sandwich core and flexural stiffness of all-composite sandwich constructions are determined with three-point beam bending tests, and compared with the analytical and finite element analysis solutions. Additionally, Digital Image Correlation (DIC) system is employed to validate the experimental results by monitoring the displacements. The effect of orientation of the composite core material with respect to the beam axis on the shear modulus of the core material itself, flexural stiffness of the sandwich beam, maximum loading, and the maximum stresses on the sandwich panel are also examined. Comparable results are achieved through experiments, finite element and analytical analyses.

Shear Test on CFRP Full-Field Measurement and Finite Element Analysis

2010 ◽  
Vol 112 ◽  
pp. 49-62 ◽  
Author(s):  
Sébastien Mistou ◽  
Marina Fazzini ◽  
Moussa Karama
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Modulus ◽  
Shear Test ◽  
Image Correlation ◽  
Optical Methods ◽  
Strain Gauges ◽  
Element Analysis ◽  
Full Field ◽  
Full Field Measurement

The purpose of this work is to study the Iosipescu shear test and more precisely its ability to characterize the shear modulus of a carbone/epoxy composite material. The parameters influencing this identification are the fibre orientation, the geometry of the notch and the boundary conditions. Initially these parameters were studied through the finite element analysis of the shear test. Then, the measurement of the shear strains was carried out by traditional methods of measurement (strain gauges) but also by optical methods. These optical methods: the digital image correlation and the electronic speckle pattern interferometry (ESPI); allow for various levels of loading, to reach a full-field measurement of the shear strain. This enabled us to study the strain distribution on the section between the two notches. The finite element model enabled us to study the parameters influencing the calculation of the shear modulus in comparison with strain gauges, image correlation and ESPI. This work makes it possible to conclude on optimal parameters for the Iosipescu test.

scholarly journals Vertical Stiffness Functions of Rigid Skirted Caissons Supporting Offshore Wind Turbines

2021 ◽  
Vol 9 (6) ◽  
pp. 573
Author(s):  
AbdelRahman Salem ◽  
Saleh Jalbi ◽  
Subhamoy Bhattacharya
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Offshore Wind ◽  
Element Analysis ◽  
Vertical Stiffness ◽  
Closed Form Solutions ◽  
Principal Axes ◽  
Modes Of Vibration ◽  
Bending Modes ◽  
Tower Vibration

Suction Bucket Jackets (SBJs) need to be fundamentally designed to avoid rocking modes of vibration about the principal axes of the set of foundations and engineered towards sway-bending modes of tower vibration. Whether or not such type of jackets exhibit rocking modes depends on the vertical stiffness of the caissons supporting them. This paper therefore derives closed form solutions for vertical stiffness in three types of ground profiles: linear, homogenous, and parabolic. The expressions are applicable to suction caissons having an aspect ratio (depth: diameter) between 0.2 and 2 (i.e., 0.2 < L/D < 2). The work is based on finite element analysis followed by non-linear regression. The derived expressions are then validated and verified using studies available in literature. Finally, an example problem is taken to demonstrate the application of the methodology whereby fundamental natural frequency of SBJ can be obtained. These formulae can be used for preliminary design and can also be used to verify rigorous finite element analysis during detailed design.

scholarly journals ANALYSIS OF ANALYTICAL MODELS AND THE DEPENDENCES REALIZED BY THEM FOR DEFINITION OF MECHANICAL CHARACTERISTICS OF COMPOSITE FILLERS

2021 ◽  
Vol 1 (161) ◽  
pp. 8-18
Author(s):  
A. Kondratiev
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elastic Modulus ◽  
Information Technologies ◽  
Mechanical Characteristics ◽  
Sandwich Structures ◽  
Accuracy Assessment ◽  
Analytical Models ◽  
Element Analysis ◽  
Shear Moduli

The analysis of the accuracy of analytical models and the mechanical properties they implement is carried out for various types of composite aggregates of sandwich structures. The accuracy assessment of approximate analytical dependencies of the mechanical characteristics of the composite honeycomb core is given. The applicability of analytical dependencies at the initial stages of the design of cellular structures is established. The accuracy of the results of a numerical experiment is noted. This is due to the approximate nature of standard test methods. Both for the elastic modulus and for the shear moduli, their values obtained on the basis of information technologies of finite element analysis exceed their corresponding values determined by analytical dependencies. This excess over the corresponding analytical values for the shear moduli is close to a constant value for various reinforcement angles and does not exceed 1.14. For the elastic modulus of the first kind, the excess varies from 1.03 to 1.8 for various angles of cell reinforcement. The analytical dependences of the reduced mechanical characteristics of the tubular aggregate are obtained. The idea of the method for determining the mechanical characteristics of a tubular filler is to fulfill the requirement of equality of the relative axial and shear deformations of a conventional continuous type element and a real one, selected within one tube, taking into account only its material. The conclusion is drawn that the mechanical characteristics of the tubular aggregate, determined by the analytical model, to different degrees differ from the corresponding characteristics obtained on the basis of information technology of finite element analysis. Moreover, the difference in the elastic moduli of the first kind is much smaller than in the shear moduli. The reasons for these discrepancies are analyzed. It is justified and recommended to use constant correction factors for the analytical values of the reduced mechanical characteristics of the tubular aggregate, allowing their further use in the calculation of plate and shell sandwich structures.

A Different Approach for Obtaining the Shear Moduliof a Composite Material

2020 ◽  
Vol 70 (12) ◽  
pp. 4470-4476
Keyword(s):  
Finite Element ◽  
Composite Material ◽  
Elastic Modulus ◽  
Shear Modulus ◽  
Finite Element Model ◽  
Element Model ◽  
Layered Composite ◽  
Element Analysis ◽  
Shear Elastic Modulus ◽  
Elastic Characteristics

In recent years the composites materials gained a major importance in all fields of engineering, because they offer a successful replacement for classical materials conferring similar elastic-mechanical properties to metal or non-metal alloys presenting several advantages such as reduced mass, chemical resistance etc. Considering this, during the design, dull knowledge of the elastic-mechanical characteristics is of high importance. The present paper aims to create a finite element model able to predict the shear elastic modulus of a double-layered composite material based on the elastic characteristics of its constituents. For this, once the elastic characteristics of the constituents determined, they could be used in the finite element analysis obtaining consequently the shear modulus for the composite material. Also, the shear elastic modulus of the resultant composite was determined experimentally. The results of the finite element model were compared to the experimental values in order to validate the finite element analyses results. Keywords: composites, fiberglass, shear modulus, FEM

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