An identification of nonlinear dissipative properties of constructional materials at dynamical impact loads conditions

Abstract

The dissipative properties of most structural materials are usually described by a viscous damping parameter determining the rate of energy dissipation. The parameter stem from the traditionally adopted rheological Kelvin model. However, the analytical description of the dynamic properties of modern structural materials, including biological materials, often poses difficulties, due to the fact that the stress-strain dependence in these materials is not linear. Therefore a method of determining of nonlinear form of dissipative characteristic D x; _ x ð Þ(is presented. As it is assumed, mathematical function of the characteristic consist of nonlinear term g(x) of arbitrary form and so called mixed term j(x)v where j(x) is a function of deformation x and v-velocity of deformation. The deformation of a viscoelastic element which is made of tested material can be measured as displacement x of a single mass m in relative to a point of a complex vibratory system. The proper analysis of the mass m movement allows to evaluate the form of the functions g(x) and j(x) what is a fundamental aim of the presented method. Beside of analytical method description some computer examples are presented. The method can be useful in evaluation of modern structural material properties (e.g. composites).

Testing of an industrial robot’s accuracy and repeatability in off and online environment

“…In order to achieve the maximum efficiency and reliability of automated and robotic production lines, numerous scientific studies are carried out aimed at both the development of technical means themselves, as well as methods for their programming and exploitation [1,2,4,5,8,10,11,13,18]. In the case of industrial robots, the accuracy and repeatability of positioning are extremely important features affecting their operation [3,6,7,12,19,21,22,26].…”

Analysis of the properties of antifriction composites based on aluminum alloy's grinding waste

“…Another approach to development of friction parts is a use of powder manufacturing technology. Authors of works [7,8] proved possibility of addition of various functional substances to a composition of an initial charge. Substances provide composite operation characteristics, which we can't achieve at application of traditional metallurgical methods.…”

“…Efficiency of a lubricating action increases at an increase in a load due to a decrease in a displacement stress. Papers [7][8][9] presented numerous studies on properties of composite materials based on copper, nickel and aluminum with inclusions of different types of solid lubricants. However, data on a use of aluminum alloys for production of new composite components of any purpose are limited due to existing technological difficulties in manufacturing of powder materials and high prices of raw materials (powders) and equipment for its manufacturing.…”

“…We know [3,7] that activation of solids particles the mechanism of lubrication due to destruction of bonds inside a crystalline lattice of particles material. The destruction of solids particles affects the friction mechanism, and, in this case, the most important factors, which determine the mechanism of lubrication action of solid lubricants, will be structural properties (type, shape and size of a crystalline solids lattice) and adhesion ability [7][8][9][10].…”

Numerical simulation of dust explosion in the spherical 20l vessel

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