Characterization Of Elastic Moduli Research Articles

Characterization of elastic modulus and hardness of brittle solids by instrumented indentation

Characterization of elastic modulus and hardness of brittle solids by instrumented indentation

Characterization of elastic modulus at glass/fiber interphase using single fiber composite tensile tests and utilizing DIC and FEM

The bonding performance and formation of the interphase region between fiber and matrix have significant effects on the strength and durability of composites. A new approach, involving combined experimental and numerical analyses, has been developed to avoid the shortcomings and scattering associated with local experimental methods. For this purpose, tensile tests are performed on specimens fabricated from a single glass fiber and epoxy resin. The elongations for specified lengths are measured using the digital image correlation (DIC) technic. The size of the fiber diameter and specimen section are also measured from SEM images. The obtained experimental displacements for micro tensile tests are used in an inverse elastic finite element solution to obtain the interphase elastic modulus. It is shown that, considering the interphase thickness of 1.0 μm that is more realistic, the interphase elastic modulus is in the range of 12 ∼ 19 GPa. However, the performed sensitivity analysis shown that considering interphase thickness ranging from zero to 2.0 μm the interphase elastic modulus varies between 9 and 46 GPa. It is shown that the proposed procedure can be used to obtain the overall mechanical properties of the matrix/fiber interphase in long fiber composites.

Characterization of elastic moduli with anisotropic rock physics templates considering mineralogy, fluid, porosity, and pore-structure: A case study in Volve field, North Sea

A practical methodology was designed to characterize mineralogy and the rock microstructure by constructing anisotropic rock physics templates (ARPTs) based on the Effective Medium Method (EMM). The ARPTs consider parameters such as pore aspect ratio (α), porosity, fluid saturation, and elastic properties of rock minerals. A three-stage methodology was applied to an oil well for a sandstone formation in the Volve field, North Sea. The first stage is the petrophysical evaluation, which is validated with core data. The second, the inversion scheme with differential effective medium (DEM) was used to predict aspect ratios in depth. The obtained results characterize the sandy formation setting intergranular porosity with 0.12 < α < 0.3, although there is also the presence of stylolites caused by the dissolution mechanism between quartz, feldspar, mica, calcite, and clay. The validation of the pore-structure is accomplished with thin sections. The last stage comprises the construction of ARPTs, which includes the axial and two transversal templates of Young's modulus versus Poisson's ratio. These templates are used to characterize lithology, porosity, pore-structure, and the mechanical behavior of the sandstone formation from well logs and gave invaluable information about the pay zone. In addition, because the lithotype interpretation proposed is merely borne by rock's elastic properties, it has the potential to be scaled to field scale by using seismic inversion data.

Characterization of Elastic Modulus of Laser Cladding Coatings Using Laser Ultrasonic Method

Characterization of Elastic Modulus of Laser Cladding Coatings Using Laser Ultrasonic Method

Nondestructive characterization of elastic modulus of APS Ni–5Al/10hBN coating on stainless steel 304 under high temperature

The failure mechanisms of coatings, under high thermo-mechanical loads, can be examined through finite element simulations. However, mechanical properties such as Young’s modulus and Poisson’s ratio are necessary to achieve an accurate model. In this study, nickel–aluminum with hexagonal boron nitride (NiAl/hBN) is deposited on stainless steel 304 substrate using atmospheric plasma spray technique. The effect of the hydrogen content in the plasma-formed gas on the microstructure, hardness, and porosity of the deposited layers is examined. Also, the mechanical properties of the coating are measured at ambient temperatures using non-contact laser ultrasound technique. Results indicated that the flow rate of hydrogen has a major impact on the coating structure and elastic properties. The inhomogeneity in the coating can be minimized by decreasing the hydrogen flow rate. The coating Young’s modulus was increased at room temperature, which slowly decreased while increase in atmospheric temperature. The behavior of Young’s modulus at high temperature causes decrease in flexural strength. In addition, the back calculations are well agreed with experimental results.

Characterization of elastic modulus and work of adhesion in elastomeric polymers using microinstrumented indentation technique

This study combines Johnson–Kendall–Roberts (JKR) theory with the instrumented indentation technique (IIT) to evaluate the work of adhesion and modulus of elastomeric polymers. Indentation testing was used to obtain load–displacement data for contact between a tungsten carbide indenter and the elastomeric polymer. The JKR contact model, which was designed to take polymer viscoelastic effects into account, was applied to adjust the contact area and the elastic modulus, which the Hertzian contact model would respectively underestimate and overestimate. In addition, we obtained the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between the JKR contact radius and applied load without measuring the contact radius optically, we used a relation between applied load and contact stiffness by examining the correlation between the JKR contact radius and stiffness through dimensional analysis with 14 elastomeric polymers. This work demonstrated that the interfacial work of adhesion and elastic modulus of a compliant polymer can be obtained from simple instrumented indentation testing without area measurement, and provided an algorithm for compliant polymer characterization.

The Characterization of Elastic Moduli and Damping Capacities of Graphite/Epoxy Composite Laminated Beams in Hygrothermal Environments

The extensive utilization of polymeric composite materials in commercial applications has mandated that the dynamic response characteristics of these advanced materials be carefully studied under hygrothermal service conditions in order that viable design guidelines be distilled for practicing engineers. Significant progress has been made in understanding both the dynamic response characteristics of polymeric composite materials under iso-hygrothermal conditions and also their static mechanical response characteristics in hygrothermal environments. However, these two areas have generally been treated by the research community as distinct disciplines, and there is a significant void in the literature on evaluating the hygrothermoelastodynamic response of polymeric composite materials. This paper partially addresses this void by presenting a coherent combination of theoretical and experimental investigations on studying the dynamic elastic moduli and damping capacities of composite laminated beams fabricated from Hercules AS4/3501-6 prepreg and exposed to different hygrothermal conditions. The favorable cor relation between the theoretical predictions based on the generic model developed herein and the experimental response-data is anticipated to provide the basis for establishing viable design guidelines for practicing engineers in the aerospace, defense and automotive industries.