Time filter

Source Type

Bocian M.,Wroclaw University of Technology | Jamroziak K.,Gen Tadeusz Kosciuszko Military Academy Of Land Forces | Kulisiewicz M.,Wroclaw University of Technology
Meccanica | Year: 2014

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 ̇) (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 κ(x)v where κ(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 κ(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). © 2014 The Author(s). Source

Kosobudzki M.,Gen Tadeusz Kosciuszko Military Academy Of Land Forces | Stanco M.,Wroclaw University of Technology
Eksploatacja i Niezawodnosc | Year: 2016

The underframe of a truck is one of the most loaded parts of a vehicle. It is a spatial unit and it must be strong enough to withstand random loading within many years of maintenance. The most severe form of deformation is in torsion. So, frame side members are often made from elements with channel sections, rigid for bending and flexible for torsion. Authors have conducted the research of 6x6 high mobility wheeled vehicle assigned to 20-feet container. Their load-carrying structure is made from two separate underframes: longitudinal and auxiliary connected with bolted joints. The goal of the research was to check if the torsional angle of deformation of the underframe during static and dynamic tests is within an acceptable range. The static test was carried out for the main underframe first to assess the characteristic of torsional stiffness without the auxiliary frame. After connecting both frames together the measure was conducted again. In the experiment the diagonal wheels were lifted up and the resulting displacement of the ends of the frame side members was recorded. Simultaneously the strain at chosen points of the underframe was measured with a system of turned half bridge strain gauges. After calibrating the measuring system a second part of experiment was conducted within proving ground tests when the vehicle was fully loaded. The collected strain data at chosen points allowed for calculating the resultant displacement of the ends of the frame side members in function of sort of road and to indicate the influence of auxiliary frame on increasing the torsional stiffness of the underframe. © 2016, Polish Academy of Sciences Branch Lublin. All rights reserved. Source

Kosobudzki M.,Gen Tadeusz Kosciuszko Military Academy Of Land Forces
Advanced Materials Research | Year: 2014

Nowadays modern mechanical objects, above all that which are use in special purposes use the most innovative solutions that should increase their functional quality [1]. The maintenance of those mechanical objects involves the high financial expenditures which is strictly connected with the total life cycle costs. To reduce those costs and keep up the mechanical readiness index on acceptable level the condition based maintenance strategy is more and more desirable. This is connected with the total durability of the element and its threshold value. So, in the strategy the tracking of the loss of maintenance potential of analyzed element is necessary and evaluation of the residual durability as well. In the paper, the method of life estimating the chosen element of high mobility vehicle was presented. This class of vehicle is constructed to move in various on- and offroad conditions. In many cases this vehicles play a key role in public utilities and armed forces. Very often the high mobility chassis has been used to create a special purpose vehicle. The total cost of life cycle this class of vehicles is considerable, so a method to check the loss of maintenance potential of vehicle is desirable [2]. To solve this problem and draw up a mechanical and maintenance characteristics of a vehicles profiled ground tests have been created and various tests have been carried out [3]. This approach have been time consuming and very expensive. What is more, results of tests are strictly connected with sort of roads selected to tests and depends on a lot of random variables. So, a worked out characteristics are statistically correct rather for the whole group of vehicle than to every single one. The proposed method is able to track the loss of maintenance potential of a critical element of every one vehicle of this class in real road condition. The method joins possibilities of calculating the load in frequency domain with fatigue strength of the most loaded points in an analyzing unit according to its FEM model. The developed method enabled to characterize relationship of decrease of maintenance potential of the critical element in terms of the type of the road and surface, and the speed of movement [4]. The method makes it possible to forecast the residual work capacity expressed in units of time and after taking the speed of movement into consideration, also mileage expressed in kilometers. © (2014) Trans Tech Publications, Switzerland. Source

Jamroziak K.,Gen Tadeusz Kosciuszko Military Academy Of Land Forces | Bocian M.,Wroclaw University of Technology
Advanced Materials Research | Year: 2014

The article presents an analysis of impact energy dissipation process with selected nonclassical dynamic models. Identification of impact energy dissipation phenomena in layered mechanical systems (for example: composite ballistic shields) is a great challenge, because on the one hand a model with parameters responsible for the energy dissipation is being sought on the one hand and on the other it is necessary to optimise the number of parameters. The sought model should be reduced to a simple description of the phenomenon and should contain a complex reproduction of the whole mechanical system. In this case the impact energy dissipation was described using selected degenerate systems. Models were treated by extortion surge having a specific impulse of force. The mathematical description of the pulse excitation was carried out using the energy and potency balance equations. The verification of mathematical identification equations was conducted using a computer simulation technique for the selected model’s parameters. © (2014) Trans Tech Publications, Switzerland. Source

Stanco M.,Wroclaw University of Technology | Kosobudzki M.,Gen Tadeusz Kosciuszko Military Academy Of Land Forces
Materials Today: Proceedings | Year: 2016

The paper contains a description of chosen technical problems that occur during tests of 4x4 high mobility wheeled vehicle. An example of how to design tests in order to confirm that a vehicle meets requirements was presented. Additionally examples of recorded accelerations during test of a high mobility vehicle were shown. © 2016 Elsevier Ltd. Source

Discover hidden collaborations