Papers by Author: Stefan Kaczmarczyk

Abstract: Modelling the dynamic performance of an elevator car system represents a complex task and forms an important step in the elevator system design procedure. The need to consider the behaviour of passengers travelling in the car complicates the procedure further. This paper presents an original approach to identify the stiffness and damping characteristics of an elevator car system. A simplified model is developed and the experimental rig with a rectangular elevator platform fixed on the top of four silent blocks attached to a shaker is setup. The transmissibility measurements are carried out with a harmonic excitation applied first to a platform with no passenger load and then to the platform with one passenger within the frequency range of 1 – 20 Hz. A single person standing on the platform is employed in order to assess the passenger’s contribution to the dynamic behaviour of the elevator car system. The curve fitting technique implemented in MATLAB is used to determine the damping and stiffness coefficients both for the empty car system and the car-passenger system. Investigation on the tolerances for both parameters is carried out. An approach to simplify the experimental procedure and to reduce the number of individual tests is proposed.

Abstract: This paper focuses on the investigation of the autoparametric coupling effects and modal interactions in a suspension rope system with a time varying length. Equations of motion of a multi-degree-of-freedom discrete, non-stationary and non-linear model are presented and are used to analyze the dynamic response of an elevator suspension rope system under resonance conditions. The equations of motion involve quadratic and cubic non-linear terms which are responsible for the modal interaction between the lateral and longitudinal oscillations of the rope and the car motions. The model takes into account the periodic excitations caused by motion of the host structure. The results confirm that adverse responses may arise and internal autoparametric resonance phenomena may occur.

Abstract: Traction drive elevator installations employ ropes of variable length as a mean of car and counterweight suspension. The inertial and elastic characteristics of elevator suspension systems depend on the rope construction and vary slowly during the elevator travel. The system suffers from vibrations caused by various sources of excitation. This paper presents the analysis of the dynamic response of the suspension system employing traditional steel wire ropes as well as ropes constructed of aramid fibers. The equations describing the lateral response of the system subjected to a boundary periodic excitation are solved numerically. The results show that the entire rope is subjected to repetitive low frequency transient resonances. Consequently, the structural integrity of the suspension ropes is compromised. The issue of active vibration control and the feasibility of the integration of shape memory alloy elements within the suspension rope design are discussed.