Development and validation of a numerical model for predicting forklift truck tip-over

Abstract

The aim of this paper is to present the dynamic behaviour modelling performed for a forklift truck and the validation of this model. The intention is to develop a permanent tool allowing both common and critical driving situations (especially that of lateral tip-over) to be simulated for this type of vehicle. The medium-term aim is to use this model as a tool to facilitate designing, training and preparing safety standards with a view to reducing the number of accidents related to this machine, which, on average, still cause nearly 10 deaths each year. This paper describes the forklift truck mechanical model and the tyre model. A Pacejka's lateral tyre model was used and integrated into the forklift truck model. The interacting forces and moments between the wheels and the ground are, therefore, computed at all times. Test bench-measured data, characteristic of the dynamic behaviour of several tyres, were used to identify the parameters of the Pacejka model. We studied the limits of this model adapted in this case to tyres with characteristics different from those of the car sector. Track testing was performed using a safe-test forklift truck. The purpose of these tests was to measure trajectory characteristics (velocity, position, acceleration and slip angle) and to compare them with model-based predictions, allowing validation of the robustness and accuracy of this model. Situations involving partial (up to 15 • ) tip-over were included. The quantities measured during testing were compared with the calculation results obtained for identical driving configurations. There was a close calculation/measurement correlation when performing a wide 'J-turn' (with and without tip-over) when following circular or slalom trajectories. The calculation/measurement correlation was less close when the forklift truck performed a sharp 'J-turn', for example. Model limits can be derived from the observations, data processing and calculations.

Virtual Testing of Counterbalance Forklift Trucks: Implementation and Experimental Validation of a Numerical Multibody Model

“…Because of the specifications mentioned above, ground roughness and irregularities, such as speed bumps and potholes, can significantly affect the dynamic response of forklifts. Indeed, they may induce severe vibrations, high transient dynamic loads on the vehicle chassis and other components, and vehicle instability, hence possibly causing durability and safety issues [5][6][7][8].…”

Numerical modelling of the forklift tip-over to test effectiveness of the safety components

“…[4] using numerical simulation, e.g. [3]. The use of numerical simulation has many advantages, among others it enables testing of many different safety components and scenarios.…”

“…The simulation was performed for several different configurations include three speeds: 0 km/h; 13.5 km/h and 23 km/h. The overturning forklift model was validated based on experimental results [3] for 0 km/h, [4] for 13.5 km/h and based on real-life accident reconstruction [5] for 23 km/h. For each test configuration forklift model was equipped with the following safety components: two-, three-, four-point seatbelts (2B, 3B, 4B), support structure to maintain the operator in the seat so-called seat wings (SW) ( Fig.…”

Effectiveness tests of safety components in case of forklift tip over

“…elementy bezpieczeństwa (np. pasy bezpieczeństwa) [2], [3]. Zastosowanie manekina pozwala na oszacowanie urazów jakich doznałby operator gdyby symulowany wypadek wydarzył się naprawdę co jest podstawą do określania skuteczności działania badanych elementów.…”

“…Wózek przewracano dzięki zastosowaniu modelu wychylnej platformy. Funkcja opisują-ca przechylanie platformy została opracowana na podstawie pomiarów, jakich dokonano podczas przewracania rzeczywistego wózka jezdniowego [2]. Drugim wariantem symulacji było przewrócenie wózka jadącego z prędkością 13,5 km/h.…”