Discrete approach to thermoelastic failure.
Most of experimental and numerical results show that material, during all
stages of its loading, undergoes various structure transformations. These
transformations connected with heat liberation and absorption. Along with band
formation and damages generation [1-3], in heterogeneous material, for
instance, consisting of soft matrix and hard inclusions, difference of
material properties causes forming of high thermal gradients near interface
zones. On the other hand, heat absorption or emission in local area leads to
its deformation and forms complex stress fields in the specimen.
Powerful heat flows can intensify damages generation and, as a result, to
accelerate material failure. It is very significant for industrial
applications relating to intensive heat propagation, particularly, in the case
of dynamic loading.
In the present study set of numerical experiments were undertaken. Taking into
account close connection between thermodynamic and mechanical effects in such
phenomena, two kinds of approaches were used for more thorough investigation.
Namely, discrete method based on Cellular Automata approach and continual net
method (coordinate split).
At present, there are promising approaches describing fracture behavior,
taking into account the random nature of local failure[4-5] On the base of
previous investigations , model of "quantum-like" transition (QLT) of
thermal energy was developed and tested on bistable CA approach. On the
assumption of good results of this method, it was augmented by account of
thermal expansion and stress-strain dependencies in each local area (i.e. in
each single cellular automaton).
In addition to the initial model, where heat "jumps" in automaton providing
neighbors for energy emission or absorption, presented approach takes into
account cracks generation and propagation along interfaces between areas with
different properties. Localization of deformation preceding the fracture was
studied as well. Comparison of the results obtained with experimental study
shows good accordance, so it allows evolving this approach and using it in
various industrial applications.
1. V.E. Panin, Surface layers of solid as a mesoscopic structural level of
deformation, Phys. Mesomech., 4, No. 3, p. 5.
2. E.Soppa, S. Schmauder, G. Fischer. Numerical and experimental
investigations of the influence of particle alignment on shear band formation
in Al/SiC // Proceedings of the 19th Riso International Symposium on Materials
Science: "Modelling of Structure and Mechanics of Materials from Microscale to
Product", 1998, p. 499
3. S.G. Psakhie, D.D. Moiseyenko, A.Yu. Smolin, et. al. The features of
fracture of heterogeneous materials and frame structures. Potentialities of
MCA design // Computational materials science, 1999, v.16, p. 333
4. L.L. Mishnaevsky Jr., S. Schmauder. Damage evolution and localization in
heterogeneous materials under dynamical loading: stochastic mdelling //
Computational mechanics, 1997, v.20, p. 89
5. L.L. Mishnaevsky Jr. Determination for the time-to-fracture of solids //
International journal of fracture, 1996, v.79, p. 341
6. D.D. Moiseyenko, L.L. Mishnaevsky Jr., S. Schmauder. Discrete approach of
heat flows applied to thermoelastic modeling // Proceedings of the 2nd
All-Russian conference for young scientists: " Physical Mesomechanics of
Materials", 1999, p. 81 (in Russian)