Distribution simulation stress testing

Abstract Coupled THM simulation of the FEBEX, which is the full-scale in-situ Engineered Barrier System Experiment performed in Grimsel Test Site in Switzerland, is one Task in the international cooperation project DECOVALEX III. In the Task, the simulation of the thermal, hydraulic and mechanical behaviour in the buffer during heating phase is required, e.g. the evolutions and the distributions of stress, relative humidity and temperature at the specified points in bentonite buffer material. 

Similar well fitting simulation curves for the experimental stress-strain data as those shown in Fig. 46b can also be obtained for higher filler concentrations and silica instead of carbon black. In most cases, the log-normal distribution Eq. (55) gives a better prediction for the first stretching cycle of the virgin samples than the distribution function Eq. (37). Nevertheless, adaptations of stress-strain curves of the pre-strained samples are excellent for both types of cluster size distributions, similar to Fig. 45c and Fig. 46b. The obtained material parameters of four variously filled S-SBR composites used for testing the model are summarized in Table 4, whereby both cluster... 

Abstract A methodology for quantifying the contributions of hydro-mechanical processes to fractured rock hydraulic property distributions has been developed and tested. Simulations have been carried out on discrete fracture networks to study the sensitivity of hydraulic properties to mechanical properties, stress changes with depth, mechanical boundary conditions, initial mechanical apertures and fracture network geometry. The results indicate that the most important (and uncertain) parameters for modelling HM processes in fractured rock are fracture density and rock/fracture mechanical properties. Aperture variation with depth below ground surface is found to be of second order importance. 

The occurrence condition of shear fracture is examined on the basis of the Coulomb criterion. The averaged shear stress across the fracture plane in the simulated hydraulic stimulation tests is plotted in Fig. 5, as a function of the effective normal stress across the fracture plane. The steady-stale pore pressure distribution given from Equation (1) is averaged over the fracture plane and is used to compute the effective normal stress. Triaxial compression tests have been performed on the granite using the same apparatus shown in Fig. 

In the same way a shear test can be simulated. The geometry and the boundary conditions are shown in Fig. 21.5, while Figs. 21.6 and 21.7 show the distribution of the shear strain, the shear stress, the microstructural flux, and the mi-crostructural parameter, respectively. Again, according to different Dirichlet data for ic, both types of boundary layers are generated. The results are qualitatively the same as in the tension test. 

It is crucial to simulate the in-service stress distribution of the component as closely as possible during the proof test. This is not always feasible, for example in the case of thermal stresses simulated by mechanical ones. To gain sufficient safety, a large value of the proof stress can be chosen, although this has the disadvantage of producing unnecessary scrap parts. 

Creep experiments may provide complementary information on the viscoelastic behaviour of biomaterials, especially if the tests are performed in simulated physiological conditions. Creep tests also allow for a better prediction of the long-term in vivo performance of biomaterials. It has been suggested that creep of acrylic cement allows the expansion of the cement mantle and subsequent prosthetic subsidence without causing cement fracture, besides relaxing cement stresses and creating a more favourable stress distribution at the interfaces . So, this is an important property to be characterized. 

There has been considerable interplay between experimental tests, stimulated for instance by the Q-model and the OSL model, and the development of new models in response to experiments. Both experiments and numerical simulations [54,55, 59,60,81] have shown that the existence of non-isotropic textures due to different deposition procedures of sandpiles or other packing procedures can determine the way forces are transmitted and produce different stress distributions. 

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