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The storage of hydrate-bearing sediments (HBS) in the seafloor environment is influenced by several factors. It is crucial to understand the effect of the interactions between the factors on the mechanical properties of HBS. This study examines the impact of effective confining pressure, pore pressure, saturation, fine content, and clay content on the mechanical properties of HBS by using an orthogonal test (L 25 (56)) with 5 factors and 5 levels. The variation patterns of HBS mechanical properties under different conditions were investigated. The subsequent analysis further studied the influence of the sensitivity of the factors at different axial strain stages on mechanical parameters and evaluated their significance through different analytical methods. The results show that the effective confining pressure has the greatest influence on the strength, while the influence of other factors such as pore pressure, hydrate saturation, and clay content changes as the shear process. Furthermore, the degree of influence factors on secant modulus E 50 is ranked in order of significance as hydrate saturation, clay content, effective confining pressure, fine content, and pore pressure in the order of significance. A positive correlation was found between effective confining pressure and strength, whereas hydrate saturation and clay content showed an inverse relationship with secant modulus E 50. This study highlights the complex interactions between influencing factors and HBS mechanical properties, offering valuable insights for further research and practical applications. • An orthogonal test protocol with 5 factors and 5 levels was established. • The effects of the coupling of the factors at different stages on the mechanical properties were analyzed. • The sensitivity of the factor to the mechanical properties was assessed, leading to practical suggestions for exploration. [ABSTRACT FROM AUTHOR]

Modelling and simulation of 3D orthogonal and interlock fabrics have been studied for tensile applications. This involves building a geometrical model by calculating the proper dimensions of the tows, conversion of the geometrical model into finite element mesh, and subsequently, prediction of tensile properties in the direction of load bearing tows by simulation using meso-finite element modelling. For the simulation, elliptical tow cross-section with aspect ratio 11 has been preferred as the best geometrical modelling parameter. Model results obtained from finite element analysis are then compared with experimental values to authenticate the modelling methodologies. The simulated results of maximum stress at break are found to be higher than the experimental results for both the corresponding orthogonal and interlock structures. [ABSTRACT FROM AUTHOR]

An elastoplastic semi-analytical method is proposed to deal with the plastic mechanical behavior of buried pipelines subjecting to landslides based on the plane stress condition, considering the inner pressure and the temperature variation. According to the incremental theory of plasticity, the longitudinal, radial and hoop plastic strains are expressed as the corresponding equations that contain the longitudinal and hoop stresses. Considering the effect of the inner pressure and the temperature variation, the longitudinal stress is derived based on the elastoplastic-beam theory, and then the axial force can be determined based on the relation of the internal force and the stress. Combining the differential equation and the boundary condition, the transverse horizontal displacement, the bending strain, axial strain can be obtained. To verify the proposed model, the comparison of the obtained results from the proposed method and the finite element method is performed, with minor deviations of within 5.4%. Additionally, the effects of the inner pressure and the temperature variation on the strain and displacement of pipelines are investigated through parametric studies. The results show that the plastic deformation and strain are much larger when neglecting operating loads; the pipeline develops mainly the longitudinal and radial plastic deformations instead of the hoop plastic deformation. [ABSTRACT FROM AUTHOR]

Threaded-pipe connectors are commonly employed in jointing pipelines in hydraulic and pneumatic systems. In an effort to avoid catastrophic incidences from the pipeline deteriorating, it is crucial to comprehend physical and mechanical properties on the thread connections. This paper is purportedly focused on the stress-and-strain analyses of the threaded pipe connector made of Al-6061-T6 (1¼ PT), the material of construction of aircraft structures and petroleum facilities, under preload and with internal pressure. Under the preloaded junction, both first and last threads in the pipeline connection are at most susceptible. With the internal pressure, the threaded-contact stress becomes more homogeneously distributed. Because of the contact stress, poising on the first few threads under the preloaded stage, being flattened, the last thread bears the highest contact stress. Finally, we execute an empirical experiment to reveal deformation phenomenon for the threaded-pipe connector, whose result corroborates the previous simulation studies. [ABSTRACT FROM AUTHOR]

Abstract: Based on the Duncan-Chang hyperbolic nonlinear elastic material model, this paper carried out the stress and strain numerical analysis of a clay core rock-fill dam, which is a certain building reservoir dam in Yunnan province. By loading on each layer step by step and with the static nonlinear finite element simulation of deposition, it obtained the results of the stress and deformation of the clay core rock-fill dam. The calculation showed that the great difference in deformation modulus causes non-smooth variations in deformation, stress and strain between the transition area and the rock-debris fill. From the analysis it can be seen that the present design of the dam is reasonable since no any abnormal stresses and deformations occurred in the dam. Moreover, this also indicated a feasible and provided a valuable evident for the optimization of cross-section zones in a project. [Copyright &y& Elsevier]

A method for the estimation of time-dependent strains and stresses in notches subjected to a cyclic load is discussed in the paper. The proposed solution is an extension of the methodology proposed previously for notches under a steady external load. A new algorithm is proposed to predict the creep response near notches in plane stress components subjected to cyclic loads. Predictions were compared with finite element data, and good agreement was obtained for various geometrical and material configurations. [ABSTRACT FROM AUTHOR]