Anthropomorphic Manikins

In this article, Dr Krzysztof Baszczynski explores the use of anthropomorphic manikins in the study of individual fall protection equipment.

The data published by the Central Statistical Office¹ indicates that in Poland alone in 2016, there were in total 5,500 accidents associated with a fall from a height in the work environment. Among these, 32 were serious and 28 resulted in a worker’s death. This means that a fall from a height is one of the most dangerous phenomena encountered by people at their workplaces.

Increasing the level of safety of employees working in such conditions may be based on the appropriate organisational solutions, the application of collective protection measures or individual equipment protecting against falls from height. The use of personal protective equipment is one of the methods most commonly used in Poland in this area to protect the workers.

To date, the protective equipment has had to undergo tests to check its compliance with the requirements of the directive 89/686/EEC² to make it available for users in accordance with the applicable regulations. In practice, it means the applications of the requirements and test methods contained in the European Standards are harmonised with this directive.

Fall protection tools

The basic tool used so far to test harnesses protecting against falls from height (e.g. full body harnesses, work positioning belts, sit harnesses) under fall arrest conditions is a rigid torso dummy, meeting the requirements of EN 364:1992³. It is a manikin in the form of a human torso, with 100 kg mass, and the centre of gravity based on anthropometric measurements. It is used in dynamic strength tests, and in the case of full body harnesses for determining the position it assumes after fall arrest.

The manikin, due to its construction, deviates significantly from the human body in terms of mechanical parameters and therefore it is of little use for the study of the dynamic phenomena accompanying fall arrest by individual protective equipment.

Due to the importance of such tests and their indispensability in the development of individual protective equipment against falls from height, anthropomorphic manikins are a preferred choice.

Figure 1: Type Hybrid III 50th Pedestrian ATD and Hybrid III 95th Pedestrian ATD anthropomorphic manikins

As seen in Figure 1, the two types of anthropomorphic manikins looked at in this article, are:

• Hybrid III 50th Pedestrian ATD
• Hybrid III 95th Pedestrian ATD^4,5

Manikin test uses

Such manikins constitute standard equipment of laboratories conducting safety tests related to the automotive industry, aviation, sports, etc. In the CIOP-PIB laboratory these manikins are equipped with a data acquisition system enabling the measurement of the head, chest and pelvis accelerations in three orthogonal directions, forces and moments of forces in the cervical and lumbar segments of the spine, chest deflection and forces and moments of forces in the forearms, arms and thighs.

Figure 2: The anthropomorphic manikin on the test stand prepared for initiation of the fall

“data acquisition system measures forces in the cervical and lumbar segments of the spine and chest deflection”

The manikins are an element of the test stand, whose main components include:

• The supporting structure, simulating the worksite, enabling to anchor the equipment protecting against falls from a height
• A wall crane for lifting and lowering the manikin, equipped with a device for quick release of the dummy
• Construction allowing the manikin a pre-set spatial position before the start of falling
• A system for measuring the force at the anchorage point of protective equipment
• A digital camera to record the performance of the manikin and equipment during the fall arrest

Swinging motion

The equipment presented was used in the research conducted at CIOP-PIB in 2016 – 2017, the main purpose of which was to determine the mechanical phenomena accompanying the fall arrest, which terminated with a swinging motion of the falling subject and consequent collision with an obstacle within the worksite. An example of such a phenomenon is presented in Figure 3.

Fig. 3: Swinging movement of the dummy during the fall arrest and its ultimate collision with a flat obstacle

Thanks to the use of an anthropomorphic dummy, the conducted tests made it possible to analyse the causes of the swinging movement during the fall arrest and to detect its most dangerous cases. Owing to the obtained results, among others, basic requirements for protective helmets designed for simultaneous use with individual fall protection equipment were formulated.

Improving work conditions

Anthropomorphic manikins are the main measurement tool in the research undertaken at CIOP-PIB in the project implemented under the fourth stage of the multi-annual programme designed to improve labour safety and working conditions, scheduled for 2017-2019. The main goal of the research is to identify the dangerous phenomena accompanying the fall arrest, which are not detected by the standard methods of testing protective equipment. That will allow creation of improved assessment criteria and methods of testing personal protective equipment against falls from height, enabling the development of new safer designs.

Figure 4: The anthropomorphic manikin after the fall arrest by: a) retractable type fall arrester, and b) guided type fall arresters with a flexible anchor line

The examples of the dummy positions after the fall arrest by retractable type fall arrester and guided type fall arresters with a flexible anchor line are shown in Figure 4.

The anthropomorphic dummies in the CIOP-PIB laboratory were also be used in studies of the operation of detectors of safety harness overload. As a result, the correctness of the detector function indicating the necessity to withdraw protective equipment from use was confirmed.

Summary

The presented examples of the use of anthropomorphic manikins in the study of individual fall protection equipment show that they are a very valuable research tool. Thanks to their design, they allow you to approximate the real phenomena taking place during the fall arrest, and thus to better predict the dangerous situations. The use of anthropomorphic manikins can provide very valuable data necessary in the design of new constructions to protect against falls from heights.

References

1. Central Statistical Office (GUS). Wypadki przy pracy w 2016 r. [Occupational accidents in 2016]. Warsaw: GUS; 2017.
2. Directive 89/686 / EEC – personal protective equipment.
3. European Committee for Standardization (CEN). Personal protective equipment against falls from a height. Test methods. Brussels: CEN; 1992. Standard No. EN 364: 1992.
4. Humanetics. Crash Test Dummies [Internet]. Plymouth, MI, USA: Humanetics. Available from: www.humaneticsatd.com/crashtest- dummies.
5. Humanetics. Hybrid III 50M Pedestrian [Internet]. Plymouth, MI, USA: Humanetics. Available from: www.humaneticsatd.com/crash-test-dummies/pedestrian/hybridiii50m.