Tadeusz Majewski

Effect of discontinuity size on the energy absorption of structural steel beam profiles

ABSTRACT The effect of size discontinuities on the energy absorption performance of squared steel profiles is reported. Finite element simulations of the compression strength of profiles with discontinuities, placed at mid span of the steel profiles in two opposite walls, were carried out. Circular and elliptical forms of the discontinuities were evaluated. Energy absorption capabilities were increased up to 12.54% and the peak load value was decreased to 10.52% with respect to the same structure without discontinuities. A buckling effect is observed in structures with discontinuities, which contributes to reducing the peak value while the energy absorbing characteristics decrease.

Behavior of Some Objects in Series with Dynamic Eliminators of Vibrations

The paper presents dynamic eliminators of vibration which are located on some objects connected in series. It is shown that the vibrators are able to organize themselves in such a way that they may compensate the excitation. Depending on the magnitude of the excitation the vibration can be eliminated by the vibrators of the first object or the excitation enters deeper into the system and is compensated by the vibrators of the next objects. These phenomena can be observed for some parameters of the system.

Behavior of the Robot with Vibratory Excitation

The paper presents a mini robot which moves as a result of vibratory forces. The robot has elastic bristles which allow the robot to vibrate. The vibration of the robot is generated by one or two unbalanced motors. With one motor the robot moves forward and with two motors the trajectory of the motor can be controlled. The paper presents the mathematical models of the robots, simulation of their behavior, prototypes, and some parameters which characterize their properties.

Design and construction of a mini-robot with terrestrial locomotion

This paper discusses a model of vibratory locomotion with inertial excitation, the design of a mini-robot, the construction of a prototype, and its properties. The prototype had inclined elastic bristles and the excitation was induced by the unbalanced rotor. The model has two degrees of freedom. The motion of the minirobot is defined using two differential equations that use friction force in which magnitude and direction depend on the slipping velocity of bristles.

Quality of Measurement Methods for Mechanical Testing of PP-Biocomposites

The paper presents a laboratory scale testing device that allows measuring of the Young modulus of biocomposite materials. This vibration experiment gives a natural frequency of a sample that depends on its dimensions and elastic properties. The model and the equation that permit the calculation of the elastic modulus of investigated materials are presented. The discussion of the methods, comparison and errors with results reached by commercial testing machines using static or dynamic methods is also given.