Statistical approach to description of stressed state of syntactic foam microstructure

Object and purpose of research. The object of research is a composite material of the syntactic foam type (SF), which forms a heterogeneous medium consisting of a polymer matrix filled with spherical inclusions- micro spheres. The paper suggests that distribution of micro spheres in SF should be used as a qualitative measure for estimation procedures. Comparison of such distribution for various models can be used for explaining the SF efficiency estimations. Materials and methods. The initial data inputs for the study were the composition and structure of syntactic foam and characteristics of its components: polymer matrix and glass micro spheres. Numerical studies were carried out using the earlier developed structural model of SF deformation and damage. The structural model assesses the stressed-strained state of large micro sphere assemblies (models with a number of spheres about 105 are used in the study). Results obtained by the model let us use statistical methods of processing the stress raisers and identify patterns of distributions for predicting the SF strength. The results are verified by comparison with estimations by finite element models. Main results. The structural model of deformation and damage is highly effective in calculation of the stressed-strained state of micro structures with a number of micro spheres of about 105 and more. Conclusion. The structural model developed for SF makes it possible to accurately assess the stresses of its components under external hydrostatic pressure considering a large number of micro spheres. The results show excellent convergence of the stressed-strained state estimates with detailed estimations by FE models. With accurate data on the stressed-strained state of micro structure one can predict how the damage would develop and calculate the process to failure and full loss of buoyance.