Wyniki wyszukiwania - BazTech

1

Progressive collapse test of ship structures in waves

Pei Z., Xu T., Wu W.

Polish Maritime Research

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2018

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S 3

91--98

EN

The external loads and structural ultimate strength are two important aspects for the safety of ship hull girder. It may collapse in case the structural capacity is less than the external forces in extreme seas. In the present research, progressive collapse test is performed to investigate the collapse mechanism of ship structure in waves. External load with time history and corresponding structural collapse behavior are measured and discussed to demonstrate the interaction of fluid and structures.

2

Position control of a pneumatic actuator under varying external force

Zisser E., Sintov A., Shapiro A., Riemer R.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 4

1157--1174

EN

In this paper a high accuracy position control strategy for a pneumatic actuation system subjected to a varying external force is proposed. A novel approach for the mathematical modeling of the pneumatic actuator, based on energy methods, is presented. The Lagrangian is derived from combining the kinetic and potential energies, leading to formulation of the Euler-Lagrange equation of motion. The nonlinear backstepping method is applied to derive the control law, and the derivative of the potential energy is used as the controlled parameter. Experimental results show that tracking a sine wave of 0.1m magnitude produces a maximum error of ±0:008m while the actuator is subjected to a time varying external force with a magnitude ranging from 570N to 1150N.

3

Quarter car model to evaluate behaviour under road and body excitation

Niculescu A. I., Jankowski A., Kowalski M., Sireteanu T.

Journal of KONES

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2017

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Vol. 24, No. 1

265--273

EN

The paper presents a quarter car model two degrees of freedom (wheel and body), with vertical guiding system, the model being equipped with suspension stroke limiters and with excitation by wheel and/ or by body. The model reproduces elastic and damping characteristics of wheel and of rebound and compression stopper bumpers, the spring elastic characteristic and the shock absorber damping characteristic on rebound and compression, function piston speed. The road profile is generated with simple or summation of harmonic functions, or by reproducing real roads. The forces acting on full vehicle body e.g. aerodynamic and inertial forces are reproduced in the proposed quarter model by vertical forces reduced to the analysed quarter part. Thus, the model can be used for evaluation the vertical and horizontal stability at acceleration, deceleration, pitch and roll, at aerial forces, the body ground clearance and the comfort. The model can evaluate the influence of the damping and elastic characteristics of suspension and wheel, of the static position, of the vehicle load state, of the road profile and of the external forces, to the vehicle behaviour

4

Analysis of causes of pellet mill matrix wear based on a selected example

Jałbrzykowski M., Obidziński S.

Journal of Research and Applications in Agricultural Engineering

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2016

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Vol. 61, nr 2

26--31

EN

This paper presents selected results of an analysis of damage causes to pellet mill matrix. The tested pellet mill matrix was used for the traditional technological process of pellet production. The tests were carried out since matrix failure times were found out to be too short. In order to assess the causes of matrix damage, tests of chemical composition and hardness of the matrix material were performed as well as observation of microscopic points of wear, analysis in the area of parameters of the process of operation and general conditions of use of the pellet mill. Discrepancies between the chemical composition of the material of the pellet mill and the information contained in the DTR were observed. Attention was paid to a possible influence of heat treatment and operating parameters on its premature damage.

PL

W artykule przedstawiono wybrane wyniki oceny przyczyn zniszczenia matrycy granulatora. Granulator, w którym pracowała oceniana matryca, wykorzystywany był do tradycyjnego procesu technologicznego produkcji peletów. Badania wykonano z uwagi na zbyt krótki okres bezawaryjnej pracy matrycy. W celu oceny przyczyn zniszczenia matrycy wykonano badania składu chemicznego oraz twardości materiału matrycy, dokonano obserwacji mikroskopowych miejsc zużycia oraz analizy w zakresie parametrów procesu eksploatacji oraz ogólnych warunków użytkowania granulatora. Stwierdzono rozbieżność składu chemicznego materiału granulatora od informacji zawartych w DTR. Zwrócono uwagę na ewentualny wpływ obróbki cieplnej oraz parametrów pracy na jego przedwczesne zniszczenie.