Improvement of hybrid III 50th percentile finite element model for sliding configuration motorcyclist impact

Roadside safety barriers that are commonly used to restraint impacting vehicles are characterized by exposed elements that represents an excessive hazard for impacting motorcyclists, even if they are well protected by regular suit and helmet. Whilst steel made common barriers accomplish an excellent work restraining vehicles, absorbing part of the high kinetic energy that they bring into a crash, on the other hand they don’t take into account the relative softness of a human body that directly impact against them. To face the problem of a barrier that is not biker friendly, a numerical study is carried out to be capable to predict the motorcyclist behaviour during impacts and to improve the design of roadside barriers. In order to represent the two-wheeler rider during a head front impact against a roadside protection system, the numerical model of Hybrid III anthropomorphic test device (ATD) is used. Many versions of numerical ATD are made available from software developers, some of them simplified and others well detailed in constitutive parts, but they all are designed to behave as human body when he represents the occupant of a crashing vehicle. The numerical model of ATD, as it is, seems to fail reproducing the direct impact of a motorcyclist against a roadside safety barrier. In order to have a reliable instrument to be used during the design of motorcyclist protection systems, an adaptation work has been conducted on the numerical ATD’s model. Different modifications have been introduced on the Finite Element (FE) model of Hybrid III to make it reproduce the behaviour of a two-wheeler rider whose head frontally impacts a safety barrier in sliding configuration. The most important actions were conducted on the ATD’s head and neck parts and on the numerical model of a full face helmet. In particular, modifications on geometries, material parameters, FE formulation and contact definition were introduced. The validation process for the developed model passed through the comparison between experimental tests and numerical simulations realized with LS-DYNA FE software. A first calibration was conducted on the head-helmet assembly using a series of drop tests. The head of the Hybrid III was isolated from the device’s body, instrumented with accelerometers in the three directions and freely let drop onto the ground with and without helmet. The acceleration data acquired were so used as statistical basis for the calibration of the numerical head and helmet model. The head model coming from the calibration process was brought back on the Hybrid III and the entire ATD was used to simulate the impacting conditions of different experimental tests. In order to correlate the entire model, full scale crashes were reproduced: an impact of a motorcyclist rider against a concrete new-jersey and a steel continuous motorcyclist protection system (CMPS) were simulated. Part of this thesis work has been realized in GDTech S.A. in Liege (BE), and part at LaST laboratories at Politecnico di Milano (IT).