Elastic modulus

About: Elastic modulus is a research topic. Over the lifetime, 33153 publications have been published within this topic receiving 810247 citations.

Real-Time FTIR and in Situ Rheological Studies on the UV Curing Kinetics of Thiol-ene Polymers

Abstract: Real-time FTIR spectroscopy and in situ dynamic rheology were used to characterize the UV curing kinetics of a thiol-ene system containing trimethylolpropane tris(2-mercaptoacetate) and trimethylolpropane diallyl ether. The combination of these two techniques offered a powerful approach for monitoring changes in the chemical and rheological properties of the system during UV curing. Comparable gel times were independently obtained from both FTIR spectroscopy and rheology, thereby validating the comparison of data obtained from each method. The thiol conversion determined from FTIR spectroscopy was correlated with the elastic modulus obtained from rheology. The conversion increased very rapidly during the initial stages of UV curing. However, the elastic modulus did not have an appreciable value until after 65% of the thiol functional groups have reacted, following which the elastic modulus increased at a rapid rate. From the Flory−Stockmayer theory of gelation, the critical thiol conversion at the gel poi...

Micromechanics of Composite Materials

Abstract: 1 Tensor component and matrix notation- 2 Anisotropic elastic solids- 21 Elastic strain energy density- 22 Material symmetries- 23 Transversely isotropic composite materials- 24 Cylindrically orthotropic materials- 25 Young's modulus, shear modulus and Poisson's ratio- 3 Elementary concepts and tools- 31 Aggregates and constituent phases- 32 Herogeneous microstructures- 33 Representative volume- 34 Local and overall stress and strain fields- 35 Overall properties and local fields- 36 Transformation fields- 37 Work, energy and reciprocal theorems- 38 The Levin formula and the Hill lemma- 39 Universal connections for elastic moduli of fibrous composites- 310 Constitutive relations and local fields in heterogeneous aggregates- 4 Inclusions, inhomogeneities and cavities- 41 Homogeneous ellipsoidal inclusions: The Eshelby solution- 42 Ellipsoidal inhomogeneities: The equivalent inclusion method- 43 Transformed inhomogeneities- 44 Dilute approximation of overall properties- 45 Green's function and Eshelby's tensor in elastic solids- 46 Coefficients of the P tensors for selected ellipsoidal shapes- 47 Summary of principal results- 5 Energies of inhomogeneities, dilute reinforcements and cracks- 51 Energy changes caused by mechanical loads- 52 Energy changes caused by uniform phase eigenstrains- 53 Energy changes caused by mechanical loads and phase eigenstrains- 54 Energy and stiffness changes caused by cracks- 6 Evaluations and bounds on elastic moduli of heterogeneous materials- 61 Elementary energy bounds- 62 Hashin-Shtrikman and Walpole bounds on overall elastic moduli- 63 Evaluation of H-S bounds for ellipsoidal inhomogeneities- 64 Composite element assemblage bounds- 65 The generalized self-consistent method- 7 Estimates of mechanical properties of composite materials- 71 The self-consistent method (SCM)- 72 The Mori-Tanaka method (M-T)- 73 The differential scheme- 74 The double inclusion and double inhomogeneity models- 75 Applications of SCM and M-T to functionally graded materials- 8 Transformation fields- 81 Uniform change of temperature in two-phase composites and polycrystals- 82 Transformation influence functions and concentration factors- 83 Uniform change in temperature in multiphase systems- 84 Capabilities of bounds and estimates of overall and local fields- 9 Interfaces and interphases- 91 Perfectly bonded interfaces- 92 Imperfectly bonded inhomogeneities and cavities- 10 Symmetric laminates- 101 Constitutive relations of fibrous plies- 102 Coordinate systems and transformations- 103 Overall response and ply stresses in symmetric laminates- 104 Ply and constituent stress and strain averages - 105 Design of laminates for cylindrical pressure vessels- 106 Dimensionally stable laminates- 107 Auxetic laminates- 108 Laminates with reduced free edge stresses- 11 Elastic-plastic solids- 111 Yield and loading surfaces, normality and convex- 112 Hardening and flow rules- 113 Matrix form and consistency of the instantaneous tangent stiffness- 12 Inelastic composite materials- 121 Transformation field analysis (TFA) of inelastic deformation- 122 Experimental support of theoretical predictions- 123 Thermal hardening- References

Nanostructured YSZ thermal barrier coatings engineered to counteract sintering effects

Abstract: Thermal spray zirconia–8 wt% yttria (YSZ) deposits have been employed as thermal barrier coatings (TBCs) in the hot sections of gas turbines. The use of nanostructured YSZ represents an alternative for improving the performance of these coatings. Despite some initial positive research results, there are still fundamental questions to be answered on the applicability of nanostructured YSZ coatings as TBCs. These questions are related to sintering effects, which could significantly increase the thermal diffusivity/conductivity and elastic modulus values of these types of coatings in high temperature environments. In this study, nanostructured and conventional YSZ coatings were heat-treated at 1400 °C for 1, 5 and 20 h. It was observed that the nanostructured coatings counteract sintering effects, due to the presence of a bimodal microstructure exhibiting regions with different sintering rates: (i) matrix (low rate) and (ii) nanozones (high rate). Important sintering-affected properties, like thermal diffusivity and elastic modulus were studied. The thermal diffusivity and elastic modulus values of the nanostructured YSZ coatings were significantly lower than those of conventional YSZ coatings, even after an exposure to a temperature of 1400 °C for 20 h. This study demonstrates that nanostructured YSZ coatings can be engineered to counteract sintering effects and exhibit significantly lower increases in thermal diffusivity and elastic modulus values in high temperature environments when compared to those of conventional YSZ coatings.

Plasma curing of MSQ-based porous low-k film materials

Abstract: Low dielectric constant film materials with improved elastic modulus. The method of making such film materials involves providing a porous methyl silsesquioxane based dielectric film material produced from a resin containing at least 2 Si-CH3 groups and plasma curing the porous film material to convert the film into porous silica. Plasma curing of the porous film material yields a film with improved modulus and outgassing properties. The improvements in elastic modulus is typically greater than or about 100 %, and more typically greater than or about 200 %. The film is plasma cured for between about 15 and about 120 seconds at a temperature less than or about 350 °C. The plasma cured porous film material can optionally be annealed. The annealing of the plasma cured film may reduce the dielectric constant of the film while maintaining an improved elastic modulus as compared to the plasma cured porous film material. The annealing temperature is typically less than or about 450 °C. The annealed, plasma cured film has a dielectric constant in the range of from about 1.1 to about 2.4 and an improved elastic modulus.

Elastic properties of apatites

Abstract: One of the prime motives for studying the elastic properties of the apatites stems from the occurrence of hydroxyapatite, OHAp, in calcified tissue. In this paper the isotropic elastic contents of crystalline apatite solids are determined from measurements of elastic wave velocities through powders under pressure. Once obtained, these elastic constants are used to model the elastic behaviour of a two-phase composite material having one phase more rigid than the other by a factor of 2.4. The results are then used in a general discussion of the probable order of magnitude of the elastic constants of the organic non-crystalline phase in bones and teeth, under the assumption of a two-phase system.