The behavior of the material against the external forces depends on its mechanical properties, including strength, elastic modulus, fatigue behavior, and so on. Of these properties, the elastic ...modulus has the highest importance and can be a criterion for describing the tensile elasticity or the tendency of a material to deform when opposing forces are applied along its axis. A wide range of test methods is available for measuring elastic modulus, but there is some uncertainty about the reliability of modulus values and can be addressed through good experimental and careful measurement. Among these methods, the tensile method is one of the most suitable methods for determining the elastic modulus of thin materials such as fibers. In this research, a new approach developed to calculate the elastic modulus based on the force-length curve to reduce the effects of common practical errors, like non-accurate measurement of the initial length and pretension of sample that shows the accuracy of new method. Three samples of yarn and fabric of different materials were tested for tensile strength. The linear part equation of the load-length curve was calculated and the elastic modulus values were determined according to the equation and Hooke's law. The standard deviation of the modulus in this method has been significantly reduced compared to the traditional mechanical method, also, the problems of pretension and initial length of the specimen have been resolved; Furthermore, using the new approach the initial length and strain values are obtainable with higher accuracy.
Within the framework of a relativistic single-particle model, we investigate the effect of the density dependent form factor on parity violating electron scattering from a heavy nucleus in the ...quasielastic region through the leading order of the interference of the electromagnetic current and the electro-weak neutral current.
208
Pb is used as a target nucleus in the incident electron energy range up to 1 GeV. The density-dependent form factors are obtained from a quark-meson coupling model. The sensitivities of the density-dependence are studied separately for each Dirac (
F
1
), Pauli (
F
2
), and axial (
G
A
) form factors. The density enhances the parity violation asymmetry, in particular, in the forward angle region, and the density dependence turns out to be most sensitive to the Pauli form factor.
Target mass corrections to nucleon spin structure functions are analyzed. Our results show that the corrections are important to the structure functions in a large
x region. Moreover, they play a ...remarkable role to the local quark–hadron duality of the nucleon spin structure functions in three individual inelastic resonance production regions.
In this study, we tested for identifying dimensional effects of rotational stiffness of wedged and halved scarfed joint. At first, a model of stress distribution in bending was made from observation ...of joints fracture under four-point bending tests. Proposal of rotational stiffness design formula(M-Θ) was derived from this model. Under the tests, M-Θ equation values well corresponded to all types of experimental ones. In particular, rotational stiffness rose in proportion to the cube of the materials height and the cogging width and had asymptotic limit value. These tendencies corresponded to the experiment results.
An investigation was carried out to determine the appropriate values of strain to be exerted in the test for environmental stress cracking of different kinds of polymeric materials. It was found that ...for the brittle plastics the elastic region on the stress-strain curve is the best selection; for toughened plastics the strain should be selected in the plastic region; for polycarbonate, which can crack easily in a chemical medium, a strain below the yield point is suitable. These results could be used as a reference in the application of test method “Plastics-Determination of environmental stress cracking (ESC)-Ball or pin impression method”.
In this study, the new angle control method to reduce the scatter band of clamping forces has been developed. The present method simultaneously loads a bolt with torque and compressive force, and ...measures torque and angle. The friction coefficients, the snug point and the spring constants of the bolted joint can be accurately evaluated during tightening process. Thus, the scatter band of clamping force in the elastic-region can be reduced within the error of 10% under oil free or lubricated conditions by the present method. The present method have high reliability and never loss tightening efficiency. It is possible to apply the present method to the plastic region tightening.
This study investigated and clarified the relation between the piezoelectric voltage and microscopic fracture of hinoki (Chamaecyparis obtura Endl.), in particular the deformation of the ...cross-sectional wall of the tracheid in linear-elastic regions under combined compression and vibration stresses. The piezoelectric voltage-deformation (P-D) curve consisted of a linear region starting from the origin followed by a convex curved region. The linear region of theP-D curve was only about 60% of that of the load-displacement (L-D) curve. By applying combined stresses to a specimen, the cross-sectional walls of the tracheid were deformed mainly at the radial walls. When a tracheid was regarded approximately as a hexagonal prism, the elastic buckling stress of the radial wall was estimated from scanning electron microscope images and our method based on a modification of the Gibson and Ashby method. As a result, it was estimated that the elastic buckling stress was only about 80% of the stress at the proportional limit of theP-D curve. It is found that there are two consecutive regions before the proportional limit of theP-D curve: One is the region up to the spot where the radial cell wall generates the elastic buckling, and the other is the region starting from the end of the aforementioned region up to the proportional limit of theP-D curve.
The nanostructure and atomic structure ahead of the crack tip of highly oriented pyrolytic graphite has been studied by using scanning tunneling microscopy (STM) and that of mica by using atomic ...force microscopy (AFM). There are many small voids or vacancy clusters ahead of the crack tip, which can migrate with time and result in the crack tip propagating because of the interaction force between the STM pinpoint and the sample. The nanostructure and atomic structure of loaded crack tip on (001) surface of mica has been observed by AFM. The results show that there exists a severely distorted region about 10 nm in width ahead of the loaded crack tip, and in this region there are many vacancies and vacancy clusters. Around this region there is an abnormal elastic region about 110 nm in width.
PDF
