In this study, the effect of initial principal stress rotation on anisotropic behavior of medium dense Firoozkuh sand in the drained condition was studied. Hollow Cylindrical Apparatus (HCA) was used to conduct the tests in the drained condition on the medium dense specimens of Firoozkuh sand. All specimens were prepared with a height of 200 mm and outer and inner diameters of 100 and 60 mm, respectively, using dry air pluviation method. The specimens were consolidated subjected to the anisotropic initial stresses with different directions (\alphac). During consolidation, stress ratio (Rc=\sigma′ 1c/sigma′ 3c=2) was maintained equal to 2. Specimens were consolidated under an anisotropic condition in which the rotation of initial principal stresses was set to a constant value varying from zero to 450. The specimens were sheared under different inclinations of principal stress increments (\alpha\delta\sigma) varying from zero to 450. In these tests, the direction of principal stress increments (\alpha\delta\sigma) may be not equal to the direction of the principal stress due to anisotropic stresses, applied in the consolidation phase. Generally, the results showed a decrease in the shear strength of sand by increasing (\alpha\delta\sigma). The results showed that the stress-strain behavior and shear strength of medium dense sand were influenced by the inclination of initial principal stresses. Initial anisotropic principal stresses caused initial shear strains which softened the stress-strain behavior of sand. Therefore, the shear modulus and shear strength for anisotropic consolidated specimens were less than that of the isotropic consolidated specimens. The anisotropic response of medium dense sands was observed to be governed by (\alphac). It was found that the shear modulus and shear strength of sand relatively decreased and anisotropy coefficient significantly increased when anisotropic initial stress and increments of principal stresses were in the same direction. The effect of initial stress state on the shear modulus was more noticeable than that on the shear strength of sand.

The construction of geotechnical structures in sandy soils requires load bearing evaluation in undrained conditions. Undrained shear strength depends on many factors, including principal stress rotation (anisotropic behavior). However, the effect of this inclination angle (α°) is often ignored due to the difficulty in reflecting this phenomenon in laboratory research, the hollow cylinder torsional shear apparatus provides the possibility of examining the anisotropy of soils. On the other hand, most of the sand sediments contain different amounts of silt particles, which have a significant effect on the behavior of the sand, and investigating the anisotropic behavior of these mixed soils (especially in low content) has not been fully studied. This research includes 18 undrained tests using a hollow cylindrical apparatus on Firoozkuh sand with low silt content. The samples have 0, 5 and 10% silt content. Inclination angle (α°) is considered as a key parameter that shows the characteristics of anisotropy, and the values of 15, 30 and 60° are applied in the experiments. Based on the obtained results, increasing the inclination angle leads to more contractive behavior in sand. By adding a small percentage of layer, the overall structure of the sand skeleton remains constant and the samples can still be evaluated based on the general behavior of the host sand. In the samples containing 5%, reduction of contractive behavior and increase of resistance (18.5%, 12% and 7.7% for angles of 15, 30 and 60°, respectively) are observed, but with an increase of 10%, the strength is decreased (less than the host sand) and the contractive behavior is increased. In anisotropic behavior, with the increase of the inclination angle, the effect of fine grains in increasing the strength and reducing the contractive behavior of the samples as an important parameter in mixed soils is decreased.

The present paper concerns with the effect of initial stress on the propagation of plane waves in a rotating transversely isotropic medium in the context of thermoelasticity theory of GN theory of type-II and III. After solving the governing equations, three waves propagating in the medium are obtained. The fastest among them is a quasi-longitudinal wave. The slowest of them is a thermal wave. The remaining is called quasi-transverse wave. The prefix ‘quasi’ refers to their polarizations being nearly, but not exactly, parallel or perpendicular to the direction of propagation. The polarizations of these three waves are not mutually orthogonal. After imposing the appropriate boundary conditions, the amplitudes of reflection coefficients have been obtained. Numerically, simulated results have been plotted graphically with respect to frequency to evince the effect of initial stress and anisotropy.

In this work, the effects of injection initial conditions on displacement and rotation of flammable region in a twophase fuel–air cloud in open atmosphere have been studied numerically. Investigating the internal conditions of the cloud, we recognize the flammable region and study the effects of injection velocity, droplet initial size, and temperature on the behavior of this region. This study can designate the proper position for successful ignition. Validation was made by comparing the numerical and experimental results. Results show increasing injection velocity and initial size of droplet decreasing droplet initial temperature, increase the rotation of flammable region.

The present research describes the variations of the intermediate principal stress, σ2, in plane strain condition which occurs in many earth structures, such as embankment dams, retaining walls and strip footings. For this purpose a series of drained monotonic plane strain tests on Leighton Buzzard sand under different initial magnitudes of σ2 were performed. The sand samples were initially packed to dense and loose samples. The Biaxial Tester, which is able to simulate the plane strain condition and also to measure the variation of σ2 during the test, was employed in the research. It is shown that the stress-strain response of sand and its shear strength at failure do not vary significantly and almost independent of the initial magnitudes of σ2, but are dependent on its initial void ratio. This implies that if different initial values of σ2 create various directional anisotropic structures, they play no part in the plane strain tests. Also a numerical model, which is capable of including σ2, is proposed to predict particularly stress-strain response of sand and magnitude of σ2 at failure. The variations of stress ratio σ2/(σ1 + σ3) were monitored during shearing to clarify the significance of intermediate principal stress.

In this research, the effect of rotation on the free vibration is investigated for the size-dependent cylindrical functionally graded (FG) nanoshell by means of the modified couple stress theory (MCST). MCST is applied to make the design and the analysis of nano actuators and nano sensors more reliable. Here the equations of motion and boundary conditions are derived using minimum potential energy principle and first-order shear deformation theory (FSDT). The formulation consists of the Coriolis, centrifugal and initial hoop tension effects due to the rotation. The accuracy of the presented model is verified with literatures. The novelty of this study is the consideration of the rotation effects along with the satisfaction of various boundary conditions. Generalized differential quadrature method (GDQM) is employed to discretize the equations of motion. Then the investigation has been made into the influence of some factors such as the material length scale parameter, angular velocity, length to radius ratio, FG power index and boundary conditions on the critical speed and natural frequency of the rotating cylindrical FG nanoshell.