The foundation substrate's basal contact stresses are typically thought to have a linear distribution, although the actual form is nonlinear. Basal contact stress in thin plates is experimentally measured using a ...
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The foundation substrate's basal contact stresses are typically thought to have a linear distribution, although the actual form is nonlinear. Basal contact stress in thin plates is experimentally measured using a thin film pressure distribution system. This study examines the nonlinear distribution law of basal contact stresses in thin plates with various aspect ratios under concentrated loading, and it establishes a model for the distribution of contact stresses in thin plates using an exponentialfunction that accounts for aspect ratio coefficients. The outcomes demonstrate that the thin plate's aspect ratio significantly affects how the substrate contact stress is distributed during concentrated loading. The contact stresses in the thin plate's base exhibit significant nonlinearity when the aspect ratio of the test thin plate is greater than 6 similar to 8. The aspect ratio coefficient-added exponential function model can better optimize the strength and stiffness calculations of the base substrate and more accurately describe the actual distribution of contact stresses in the base of the thin plate compared to linear and parabolic functions. The correctness of the exponential function model is confirmed by the film pressure distribution measurement system that directly measures the contact stress at the base of the thin plate, providing a more accurate nonlinear load input for the calculation of the internal force of the base thin plate.
A 3D micro-creep model based on the grain-based structure and the framework of the Particle Flow Code (PFC) approach is proposed. Simultaneously, a Voronoi polyhedral technique is employed to approximatively construct...
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A 3D micro-creep model based on the grain-based structure and the framework of the Particle Flow Code (PFC) approach is proposed. Simultaneously, a Voronoi polyhedral technique is employed to approximatively construct the grain structure of the real rock salt. Based on literature research, an exponential attenuation mode controlled by the temperature and stress-level is assumed to characterize variation behavior of the parallel bond diameter (PBD) with time. This model is then configured to simulate the time-dependent deformation responses associated with the damage features of rock salt. The validity and applicability of this 3D micro-creep model are verified through comparing the steady-state creep rate, multi-steps creep responses, and microcracking modes obtained in lab tests. This work could provide a promising alternative to study the micro-creep damage mechanism of rock salt.
Dynamic oscillation rheometry in combination with repeating freeze-thaw (FT) cycles (DOR-FT) was applied to evaluate the rheological change of starch gel caused by long-term retrogradation. The gels prepared from corn...
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Dynamic oscillation rheometry in combination with repeating freeze-thaw (FT) cycles (DOR-FT) was applied to evaluate the rheological change of starch gel caused by long-term retrogradation. The gels prepared from corn, wheat, rice, potato, and sweet potato starch pastes (6%, w/w) were formed on a dynamic rheometer plate and the rheological changes induced by the FT cycles were measured while their gels remained on the rheometer plate. Comparing with the storage modulus (G) at 25 degrees C of each starch gels without FT, G of corn, wheat, rice, potato, and sweet potato starch gels after three FT cycles increased by 341, 474, 167, 1368, and 631%, respectively. The DOR-FT method enabled the evaluation of the rheological changes caused by the long-term retrogradation within 1h, which is much shorter than with the conventional puncture test. Moreover, G versus FT cycles could be expressed as an exponential function model, indicating that the functionmodel would show the FT cycle dependence for the rheological change of starch gels.
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