Numerical analysis of passive safety systems in forklift trucks

90 accidents involving forklift trucks occur each year in Poland, resulting in nearly 100 injured persons including 10-15 fatalities. The most frequent and most dangerous accidents include those caused by the loss of stability of a forklift truck with the operator inside, resulting in its tip-over. More than a half of this type of incidents have a fatal outcome. The paper describes results of tests aimed at verifying the effectiveness of passive safety systems used to protect the operator against the effects of the truck tip-over. The tests were performed with the use of numerical simulation. The authors selected 12 configurations taking into account the forklift's velocity, position of the steering wheel and seat and the operator's reaction, in terms of which selected passive safety systems were tested. In order to conduct the effectiveness tests of these systems, a simulation model was developed, consisting of numerical models of: a forklift truck, human body, ground and tested passive safety systems. This was followed by a series of simulations of the forklift tip-over with the operator inside, with the use of different passive safety systems. More than 170 simulations of possible cases were performed in total. Results, in the form of recorded resultant acceleration of the head, were used to estimate the severity of injuries for each case considered. This was used as a basis to determine the effectiveness of the passive safety systems.