Fragment Simulating Projectile (FSP) experiments using high strength steel were conducted to assess ballistic efficiency of some layered structures. Materials of single structures have been considered as: steel, ceramics, concrete and some ductile materials, The 53.78 ± 0.26 g projectiles, with 29 mm in diameter were fixed at velocities closed to 1000 m/s. The results of predictive calculations and experimental data are reported. Comparisons with LS DYNA 3D calculations show good agreement with experiments. The numerical simulation can be used for a proposal of an optimum arrangement of layered targets. and Obsahuje seznam literatury
Frequency response analysis of hybrid aluminium beam with piezoelectric actuators was performed using finite element method The finite element model was implemented in Matlab software. The one-dimensional beam element is based on Euler-Bernoulli theory and it assumes bilinear distribution of electric field potential. The piezoelectric actuators were driven by harnonic signal around the first eigenfrequency and the beam oscillations were investigated. Results were compared to experiment. and Obsahuje seznam literatury
The paper reports on the determination of basic mechanical material parameters of several concrete and alkali activated concrete and fly ash mixtures intended for the construction of segmental lining used in TBM tunneling. The results of an extensive experimental program are discussed first. The principal attention is accorded to the experimental determination of specific fracture energy from a load-deflection curve, which, when compared to numerical simulations, shows certain inconsistency with the measurements of other material data. This is supported by teh derivation of the data from inverse analysis employing the elements of soft-computing. Dynamic simulation of crack propagation experiments is suggested to reconcile the essential differences and to identify the most important impacts affecting the results of experimental measurements. and Obsahuje seznam literatury
This contribution is focused on the analysis of dynamic behavior of elastic continuum moving in liquid. The method of solution is demonstrated on the non-stationatr movement of a bar in a real, incompressible liquid. The principle of the solution is based on the modal transformation of the bar and discrete process using the finite element method (FEM). The problem is in general non-linear. However, the method introduced in this contribution allows the solution which provides gradual separation of the movement of liquid and the movement of the bar. This substitution is entered analogously on the finite element and is dependent on the normal coordinates. The result is a tensor of additional effects. and Obsahuje seznam literatury
We introduce statisch pairs in atomistic posets and study its relationships with some known concepts in posets such as biatomic and dual modular pairs, perspectivity and subspaces of atom space of an atomistic poset. We generalize the notion of exchange property in posets and with the help of it we prove the equivalence of dual modular, biatomic and statisch pairs in atomistic posets. Also, we prove that the set of all finite elements of a statisch poset with such property forms an ideal. ∇-relation is partly studied by means of statisch pairs.