China
Africa
Explore chapters and articles related to this topic
Experimental methods
Published in Roderic S. Lakes, Viscoelastic Solids, 2017
Creep experiments can be performed in a simple manner since a stress which is constant in time can be achieved by deadweight loading. Tensile or compressive creep tests on a rod are the easiest to interpret since the entire specimen is under a stress which is spatially uniform, assuming uniformity at the ends. If there is nonuniformity due to gripping conditions, use of a slender specimen allows the investigator to take advantage of Saint Venant’s principle in interpreting results. Uniform stress is advantageous if the investigator has any interest in examining nonlinear response. In bending and torsion creep tests, the stress is not spatially uniform within the specimen. Interpreting such tests is straightforward if the material behaves linearly; in that case the creep compliance can be extracted directly from measurements of force and displacement as developed earlier in Chapter 5. Measurement of displacement in creep can also be performed simply in the domain t ≥ 10 sec. Among the simplest methods are the micrometer and the microscope. The microscope can be a traveling microscope, mounted on a calibrated stage and focused on a fiduciary mark on the specimen or its grip; or it can be a microscope with a calibrated reticle. Other methods of displacement measurement will be described below. Cantilever bending of a bar is an advantageous configuration in that the end displacement can be made large enough to measure easily while maintaining small strain, by choice of the bar geometry.
Optical measurements of phase transitions in difluorophenylazophenyl benzoate thermotropic liquid crystal with specific orientated fluorine atoms
Published in Phase Transitions, 2019
Birefringence (Δn) can be measured also from the light intensity passing through the sample in LC phase by using the equation as follow [22,33–35]:The values of T⊥ and T‖ at certain wavelength and temperature were measured for compound III. The thickness t of sample equals 40 µm, which was measured by using traveling microscope. The values of Δn of compound III in N and Sm A phases at wavelength 543 nm of laser light under certain temperatures were listed in Table 4. These results are nearly the same as the values of Δn obtained from Abbe refractometer within error (±0.005) at the same temperature degrees and wavelength.
Effects of freeze–thaw cycles on mode I fracture toughness of adhesively bonded CFRP joints
Published in Advanced Composite Materials, 2023
Sota Oshima, Keisuke Kitagawa, Tomo Takeda, Hisashi Kumazawa, Koichi Kitazono
DCB tests were carried out using a universal tester (Type 5982, Instron) at crosshead speeds of 0.5 mm/min for a < 80 mm and 1 mm/min for a ≥ 80 mm. Unloading was performed after every 10 mm of crack growth to obtain the constants from the relationship between a and C in Eq. 3. After unloading, the crack length a was precisely measured using a traveling microscope. The tests were continued until the specimens split. The 5% offset approach was used to determine the onset of crack growth [20,21].
Influence of milling process parameters and significance of tools to improve the surface quality of GFRP composites
Published in Machining Science and Technology, 2022
I. S. N. V. R. Prasanth, D. V. Ravishankar, M. Manzoor Hussain, Chandra Mouli Badiganti
The machined slot widths at three different places were measured using a traveling microscope (Model RVM-201) with an accuracy of 10 μm. To determine the value of W Max, first, the vernier scale (traveling microscope) was counted as 0.01 mm. These values are substituted in Equation (1). Delamination factor (FD) was calculated by taking the average value as per Davim and Reis (2005).