Modelling of Elastic Constants of Plasma Spray Deposits with Spheroid-Shaped Voids

1998 ◽  
Author(s):  
S.-H. Leigh ◽  
G.-C. Lee ◽  
C.C. Berndt
Keyword(s):  
Elastic Constants ◽  
Plasma Spray ◽  
Constitutive Equations ◽  
Solid Mechanics ◽  
Transversely Isotropic ◽  
Stiffness Tensor ◽  
Stereological Analysis ◽  
Aspect Ratios ◽  
Spheroidal Shape

Abstract The five independent elastic constants of plasma spray deposits were calculated from constitutive equations and the microstructural information (void aspect ratios and porosity) were gained from stereological analysis. The voids within the deposit were assumed to be a spheroidal shape. The structure of the deposit was considered to be transversely isotropic with respect to the spray direction, which requires five independent elastic constants of a stiffness tensor. Solid mechanics models containing spheroid-shape voids were applied to obtain the five independent elastic constants of the deposits. The calculated elastic constants were compared to the experimentally determined values.

The Elastic Characterization of Composite Based on Ultrasonic Waves

2021 ◽  
Author(s):  
Y. H. Park ◽  
J. Dana
Keyword(s):  
Composite Materials ◽  
Fatigue Failure ◽  
Elastic Constants ◽  
Material Properties ◽  
Weight Ratio ◽  
Transversely Isotropic ◽  
Ultrasonic Waves ◽  
Material Strength ◽  
Isotropic Composite

Abstract Anisotropic composite materials have been extensively utilized in mechanical, automotive, aerospace and other engineering areas due to high strength-to-weight ratio, superb corrosion resistance, and exceptional thermal performance. As the use of composite materials increases, determination of material properties, mechanical analysis and failure of the structure become important for the design of composite structure. In particular, the fatigue failure is important to ensure that structures can survive in harsh environmental conditions. Despite technical advances, fatigue failure and the monitoring and prediction of component life remain major problems. In general, cyclic loadings cause the accumulation of micro-damage in the structure and material properties degrade as the number of loading cycles increases. Repeated subfailure loading cycles cause eventual fatigue failure as the material strength and stiffness fall below the applied stress level. Hence, the stiffness degradation measurement can be a good indication for damage evaluation. The elastic characterization of composite material using mechanical testing, however, is complex, destructive, and not all the elastic constants can be determined. In this work, an in-situ method to non-destructively determine the elastic constants will be studied based on the time of flight measurement of ultrasonic waves. This method will be validated on an isotropic metal sheet and a transversely isotropic composite plate.

scholarly journals Designing isotropic composites reinforced by aligned transversely isotropic particles of spheroidal shape

2018 ◽  
Vol 346 (12) ◽  
pp. 1123-1135
Author(s):  
Katell Derrien ◽  
Léo Morin ◽  
Pierre Gilormini
Keyword(s):  
Transversely Isotropic ◽  
Spheroidal Shape

scholarly journals Minimum energy bounds on longitudinal elastic constants of transversely isotropic unidirectional composites

2020 ◽  
Vol 476 (2239) ◽  
pp. 20190752
Author(s):  
Duc-Chinh pham
Keyword(s):  
Elastic Constants ◽  
Minimum Energy ◽  
Young Modulus ◽  
Transversely Isotropic ◽  
Longitudinal Axis ◽  
Arithmetic Average ◽  
Energy Bounds ◽  
Cylindrical Phase ◽  
Elastic Composites ◽  
Energy Principles

We consider the n -component transversely isotropic unidirectional elastic composites, the longitudinal axis of which is parallel to those of the transversely isotropic components as well as the generators of the cylindrical phase boundaries between them. From the minimum energy and complementary energy principles, with appropriate constant strain and piece-wise constant stress trial fields, optimization and iteration techniques, a set of bounds for the macroscopic (effective) longitudinal elastic constants of the composites (including the simple lower arithmetic average estimate for longitudinal Young modulus E eff  ≥  E V ) are constructed. Numerical examples are provided to illustrate the obtained results.

Do traveltimes in pulse‐transmission experiments yield anisotropic group or phase velocities?

Geophysics ◽  
1994 ◽  
Vol 59 (11) ◽  
pp. 1774-1779 ◽  
Author(s):  
Joe Dellinger ◽  
Lev Vernik
Keyword(s):  
Phase Velocity ◽  
Group Velocity ◽  
Elastic Constants ◽  
Near Field ◽  
Frequency Dispersion ◽  
Transversely Isotropic ◽  
Sh Waves ◽  
Phase Velocities ◽  
Pulse Transmission ◽  
Transmission Technique

The elastic properties of layered rocks are often measured using the pulse through‐transmission technique on sets of cylindrical cores cut at angles of 0, 90, and 45 degrees to the layering normal (e.g., Vernik and Nur, 1992; Lo et al., 1986; Jones and Wang, 1981). In this method transducers are attached to the flat ends of the three cores (see Figure 1), the first‐break traveltimes of P, SV, and SH‐waves down the axes are measured, and a set of transversely isotropic elastic constants are fit to the results. The usual assumption is that frequency dispersion, boundary reflections, and near‐field effects can all be safely ignored, and that the traveltimes measure either vertical anisotropic group velocity (if the transducers are very small compared to their separation) or phase velocity (if the transducers are relatively wide compared to their separation) (Auld, 1973).

Elastic Constants of Composite Materials by an Inverse Determination Method Based on A Hybrid Genetic Algorithm

2010 ◽  
Vol 26 (3) ◽  
pp. 345-353 ◽  
Author(s):  
S.-F. Hwang ◽  
J.-C. Wu ◽  
Evgeny Barkanovs ◽  
Rimantas Belevicius
Keyword(s):  
Genetic Algorithm ◽  
Elastic Constants ◽  
Hybrid Genetic Algorithm ◽  
Transversely Isotropic ◽  
Determination Method ◽  
Element Analysis ◽  
Plane Shear ◽  
Effective Elastic Constants ◽  
Testing Data ◽  
Out Of Plane

AbstractA numerical method combining finite element analysis and a hybrid genetic algorithm is proposed to inversely determine the elastic constants from the vibration testing data. As verified from composite material specimens, the repeatability and accuracy of the proposed inverse determination method are confirmed, and it also proves that the concept of effective elastic constants is workable. Moreover, three different sets of assumptions to reduce the five independent elastic constants to four do not make clear difference on the obtained results by the proposed method. In addition, to obtain robust values of the five elastic constants for a transversely isotropic material, it is recommended to use the out-of-plane Poisson's ratio instead of the out-of-plane shear modulus as the fifth one.

Green’s Functions for Two-Phase Transversely Isotropic Materials

1979 ◽  
Vol 46 (3) ◽  
pp. 551-556 ◽  
Author(s):  
Y.-C. Pan ◽  
T.-W. Chou
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Elastic Constants ◽  
Transversely Isotropic ◽  
Two Phase ◽  
Closed Form Solutions ◽  
Isotropic Materials ◽  
Function Solution ◽  
Present Solution ◽  
Plane Of Isotropy

Closed-form solutions are obtained for the Green’s function problems of point forces applied in the interior of a two-phase material consisting of two semi-infinite transversely isotropic elastic media bonded along a plane interface. The interface is parallel to the plane of isotropy of both media. The solutions are applicable to all combinations of elastic constants. The present solution reduces to Sueklo’s expression when the point force is normal to the plane of isotropy and (C11C33)1/2 ≠ C13 + 2C44 for both phases. When the elastic constants of one of the phases are set to zero, the solution can be reduced to the Green’s function for semi-infinite media obtained by Michell, Lekhnitzki, Hu, Shield, and Pan and Chou. The Green’s function solution of Pan and Chou for an infinite transversely isotropic solid can be reproduced from the present expression by setting the elastic constants of both phases to be equal. Finally, the Green’s function for isotropic materials can also be obtained from the present solution by suitable substitution of elastic constants.

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