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Properties of Semiconductors
Published in John E. Ayers, Heteroepitaxy of Semiconductors, 2018
Some elastic properties that are useful in heteroepitaxy are the Young’s modulus E, the biaxial modulus ϒ, the shear modulus G, the Poisson ratio ν, and the biaxial relaxation constant RB. The Young’s modulus (also called the modulus of elasticity or the elastic modulus) is a measure of the stiffness of a material. It is defined as the ratio of stress to strain: () Young’smodulus=E=stressstrain
Mechanical Properties of Metals
Published in Zainul Huda, Metallurgy for Physicists and Engineers, 2020
Strength Properties. The stress-strain curve (Figure 8.5) indicates that in the first stage of elastic behavior, the rate of straining is very small and such strain is proportional to the stress up to the proportional limit i.e. Hooke’s law is obeyed from O to A. This linear elastic behavior is given by: σ = E𝜖 where σ is the elastic stress; 𝜖 is the elastic strain; and the constant of proportionality E is called Young’s modulus or modulus of elasticity. Young’s modulus is a measure of the stiffness of the material in tension.
Basic Rheological Concepts: Stress, Strain, and Flow
Published in Kevin P. Menard, Noah R. Menard, Dynamic Mechanical Analysis, 2020
Kevin P. Menard, Noah R. Menard
where k is the spring constant. As the spring constant increases, the material becomes stiffer and the slope of the stress–strain curve increases. As the initial slope is also Young’s modulus, the modulus would also increase. Modulus, then, is a measure of a material’s stiffness and is defined as the ratio of stress to strain. For an extension system, we can then write the modulus, E, as: E=dσ/dε
Nonlocal thermoelasticity: Transient heat conduction effects on the linear and nonlinear vibration of single-walled carbon nanotubes
Published in Mechanics Based Design of Structures and Machines, 2023
Amin Pourasghar, Wenzhi Yang, John Brigham, Zengtao Chen
Since the effective thickness and width of the SWCNTs are much smaller than their length, the nonlocal constitutive relations, Eq. (2), can be simplified to the one-dimensional form as Pourasghar et al. (2021) where and are Young’s modulus and shear modulus, respectively. Employing Hamilton’s principle, the equations of motion and the related boundary conditions can be derived. According to Hamilton’s principle where is the variational symbol. First, the work done by external forces is set to be zero for free vibration analysis. By solving Eq. (14), and setting the coefficients of and to zero, one can obtain the equations of motion as
Preparation of polyacrylic latex with external crosslinking and its effect on the pressure-sensitive properties
Published in Soft Materials, 2020
Weixiao Meng, Wenshu Gao, Lin Zhu, Mengyu Liu, Xiongwei Qu
The variation of tan δ and storage modulus (G′) of PBMD-A copolymer with temperature at different DAAM contents are shown in Figure 6. Some important viscoelastic parameters obtained from the DMA curves are listed in Table 2. From Figure 6a, we can see that only one sharp transition occurs for all curves and the peak width does not change significantly, which indicates that random copolymers are formed among the reactant components. The peak of tan δ-T curve moves toward higher temperature with the increase of the DAAM content, and Tg increases from −30.3°C to −19.5°C accordingly, indicating that the formation of dense crosslinking structure effectively limited the motion of chain segments. The modulus is the ratio of stress and strain to measure the resistance of materials to deformation. The larger the modulus, the less likely the material is to deform under pressure and the higher the rigidity of the material. From Figure 6b and Table 2, it can be seen that Gʹ also increases with the content of DAAM at room temperature.
Chemical permeation of similar disposable nitrile gloves exposed to volatile organic compounds with different polarities Part 2. Predictive polymer properties
Published in Journal of Occupational and Environmental Hygiene, 2020
Robert N. Phalen, Anton V. Dubrovskiy, Brittany C. Brown, Aleksandre R. Gvetadze, Mariela Bustillos, Jessica Ogbonmwan
Modulus is the force or stress required to produce a certain elongation or strain on a material (Askeland and Fulay 2006). It is a measure of the stress to strain ratio as a material is elongated. Modulus 50–100% is the modulus (MPa) occurring between 50–100% elongation and it is a more reliable representation of molecular structure, as it relates to disposable nitrile gloves and chemical permeation, than maximum tensile strength (Phalen and Wong 2015). This is likely due to it being a more accurate representation of normal molecular bond interactions compared to the maximum stress and material failure associated with tensile strength. Tensile strength is the maximum stress a polymer can withstand just prior to breaking. In contrast, modulus is a measure of the stress to strain ratio (slope) as a material resists being stretched, which is better associated with the molecular arrangement and bonds within the polymer (Phalen and Wong 2011; 2015). Considering this, higher modulus would be indicative of additional molecular bonds or cross-linking, which should increase BT and decrease SSPR. Based on an evaluation of disposable nitrile gloves from different manufacturers, an increase in modulus 50–100% was associated with an increase in BT and a decrease in SSPR, as reported by Phalen and Wong (2015).