Jan Holnicki-Szulc

Ensuring adequate comfort and safety in vehicle motion is a subject of extensive research worldwide. Despite the implementation of new control algorithms, including those leveraging AI, the application of effective semi-active vibration dampers remains crucial for achieving optimal suspension performance. This article presents experimental studies conducted on a vehicle equipped with semi-active suspension featuring custom-designed hydraulic dampers controlled by piezoelectric valves. These innovative dampers are characterized by extremely short response times, enabling real-time adaptation to varying driving conditions. A simple control algorithm designed to operate based on real-time signals from suspension sensors is introduced and evaluated. The experimental setup, including the measurement system used during testing, is described in detail. The presented results highlight the significant potential of this approach for improving driver comfort under specific driving conditions, even without detecting road roughness ahead of the vehicle.

An approach, based on so called Virtual Distortion Method, to dynamic analysis of physically nonhnear (elasto-visco-plastic, piece-wise linear) truss structures is presented. Then, this dynamic analysis is applied to optimal design of adaptive structures (equipped with special devices allowing control of local yield limits) for improved impact absorption. The discussed strategy of damage protection initiates actuators just before collapse of local section of the structure protecting each structural element against the local failure (plastic behaviour). The second application of adaptive structure presented in this paper is shape control of railway track over a bridge. The concept of adaptive railway track, with sleepers initially elevated (with the curvature tailored according to the detected, coming train) and then yielding in a controlled way (by opening valves in hydraulic pistons) under moving train is discussed. The problem formulated as shape control requiring the minimum mean square measure of the track deflection gives, as a side effect, a significant reduction of the corresponding mean square measure of the dynamic contact forces between track and wheels.

The paper describes application of innovative, inflatable thin-walled structures for absorption of the impact loading and thoroughly investigates their crash characteristics. The proposed concept assumes inflation of thin-walled structures with compressed gas of appropriately adjusted pressure in order to improve their basic mechanical properties, enhance energy dissipation capabilities, and increase corresponding durability to impact loading. In the first part of the paper the influence of compressed gas on mechanical characteristics of aluminium beverage can is analysed experimentally and by the corresponding numerical simulations. The following section proposes and numerically verifies three diverse engineering applications of inflatable thin-walled structures for impact absorption. Finally, the last part introduces the concept of adaptive inflatable barrier and briefly presents three simple strategies of pressure control. Both the performed basic experiment and the conducted numerical simulations show the advantageous influence of compressed gas and prove the feasibility of using inflatable thin-walled structures for impact absorption.

A numerical study is presented, which tailors so-called prestress accumulation-release (PAR) strategy to mitigate free vibrations of frame structures. First, the concept of proposed semiactive technique is outlined and possible applications are specified. In the second part of the work a parametric study is discussed, which illustrates the potential of the method for mitigation of free vibrations induced by impact or other initial load scenarios. Special attention is given to the energy balance including all relevant contributions to the total energy of the considered dissipative system. The proposed technique shows a very high potential in mitigation of free vibrations, exceeding 99% of the reference amplitude after 5 cycles of vibration.

Adaptive Impact Absorption focuses on adaptation of energy absorbing structures to actual dynamic loading by using system of sensors detecting and identifying impact in advance and embedded semi-active dissipaters with controllable mechanical properties. Application of such devices allows to modify dynamic characteristics of the structure during the period of impact and to precisely control the process of energy dissipation. The paper presents an overview of research conducted at the Department of Intelligent Technologies of the Institute of Fundamental Technological Research dedicated to design and applications of various systems of Adaptive Impact Absorption. Wide range of presented examples covers adaptive hydraulic and pneumatic landing gears, skeletal systems equipped with controllable elements and detachable joints as well as adaptive inflatable structures.