Maria Datcheva

Sharp Bounds for Strains and Stresses in Uncertain Mechanical Models

Many mechanical systems, involving interval uncertainties and modelled by finite element method, can be described by parameter dependent systems of linear interval equations and response quantities depending on the system solution. A newly developed hybrid interval approach for solving parametric interval linear systems is applied to a 2D engineering model with interval parameters and the results are compared to other interval methods. A new technique providing very sharp bounds for the response quantities, such as element strains and stresses, is developed. The sources for overestimation when dealing with interval computations are demonstrated on a numerical plain strain example.

Statistical approach in soil-water characteristic curve modelling

In this paper we evaluate a number of model equations for the soil-water characteristic curve (SWCC), provided a relationship exists for each relevant soil. The models are with two parameters and relate suction to volumetric water content for values of suction higher then air entry value. Logarithmic tranformations are applied to the variables in order to find linear patern. Most of generally used models are also discussed and compared to the proposed. An example is given how to assess the experimental data to define the variable transformation and how to choose the most proper model. The procedure for estimating the air entry value is also presented.