Characteristic analysis and fuzzy simulation of falls-from-height mechanics, and case studies

Studies of Acceleration of the Human Body during Overturning and Falling from a Height Protected by a Self-Locking Device

The use of individual fall protection equipment is one of the most commonly applied methods of protecting workers whose worksites are located above the floor level. The safety of the user in such a situation depends on both the proper selection and correct use of such equipment. Additionally, aspects such as minimizing the free-fall distance before the fall arrest, as well as quick notification of an accident and efficient rescue operation, are important factors influencing safety. This paper presents a new testing method for fall arrest equipment using a test stand consisting of the Hybrid III 50th Pedestrian ATD anthropomorphic manikin and measuring set with three-axis acceleration transducers. The proposed method and test stand were developed for the design and testing of new fall protection devices equipped with electronic detection and alarm systems, for which it is necessary to determine acceleration limits in order to determine the alarm threshold. The proposed method is based on the measurement of accelerations that occur during tipping and falling from the height of an anthropomorphic manikin secured by a self-locking device. Two places of attachment of the measuring set with a three-axis acceleration sensor were analyzed at the waist belt of the manikin (abdomen and back). Moreover, the self-locking device lanyard was attached to the two points of the safety harnesses (the front and back point). The aim of the research was to check whether the acceleration values depend on the places of attachment of the measuring and anchored system, as well as to determine their maximum values. Acceleration values corresponding to fall arrest and tipping were analyzed. Limits of acceleration have been established in order to determine the threshold of alarm triggering. The non-parametric Mann-Whitney U test was used to check whether the location of the three-axis acceleration transducer and the position of the self-locking device lanyard attachment affect the value of the recorded acceleration. For results of acceleration measurements when testing the behavior of the manikin during fall arrest, no statistically significant differences were found. For results of acceleration measurements when testing the tipping behavior of the manikin, statistically significant differences occurred. This means that during fall arrest, the location of the three-axis acceleration transducer and the position of the self-locking device lanyard attachment do not matter. This work is a continuation of previous research on accelerations characterizing human body positions occurring during normal physical activities (ADL-activities of daily living).

Characteristic analysis and reconstruction method of falls from windows

Fall accidents from windows usually start indoors, so it is impossible to secure witnesses or video clips of the initial fall situation, and there are difficulties such as a complicated fall process, but related studies are rare. In this study, the types of window fall accidents are classified, and behavior characteristics are analyzed through multibody simulation analysis based on the initial fall postures and speed values from the experimental results. And, in case studies of carefully selected real events, a method for specifying the type of window fall accident is presented along with the reconstruction simulation results using a fuzzy tool for type estimation. It is believed that the results of the characteristic analysis for each type of window fall accidents and the reconstruction method proposed in this paper will be useful for related forensic investigations.