Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tham khảo tài liệu 'new trends and developments in automotive system engineering part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 68 New Trends and Developments in Automotive System Engineering interiors which have to afford impact protection for occupants namely against head impact e.g. pillars . The head injury criterion HIC is an analytical tool that is currently recognized to determine if the blow to the head exceeds a maximum tolerable threshold that causes severe injury. HIC is an acceleration-profile-based criterion that requires the knowledge of the time history of the magnitude of the linear deceleration of the centre of gravity of the head during impact. HIC defines the severity of impact to the head being given by r 25 HIC sup -1- a t dt X t2 - t1 f 1 2 _t2 -t1 1 - J 1 where a t is the resultant acceleration of the centre of gravity of the head and t2 - t1 is the time interval during the crash where the HIC value is maximised. Its value is determined between two-time points where the acceleration curve gives the maximum value of HIC. The corresponding time interval is considered as unlimited HIC or equivalent to maxima of 36 ms HIC36 or 15 ms HIC15 . In order to consider only the free motion head-form FMH during the simulation process the HIC value needs to be converted to a dummy equivalent value HIC d expressed as HIC d 166.4 0.75466 X HIC 2 The National High Traffic Systems Authority NHTSA specifies that in automotive interiors the HIC d of the FMH should not exceed 1000 to be recognized as providing head impact protection under FMVSS-201. FMVSS-201 2007 Gholami 2002 . The design criteria requires further a deceleration lower than 180 g s 1 g 9.81 m.s-2 in order to avoid severe occupant head injuries. The plastic components are therefore required to act as passive safety components. FMVSS-201 1997 . The design of polymeric parts against impact loadings is determined mainly by the high interactions between the polymer behaviour and the component geometry Viana 2006 . T. Gholami et al. investigated the response of energy absorbing polymeric egg-box like structures under an impact
