Response Analysis Of Aircraft Dummy/Seat Restraint System Under Dynamic Impact

The test method for aircraft seat which show the compliance with the dynamic requirements of the CCAR 25.562 is significant cost and long cycle.Therefore,it is of great significance to promote the development of analysis methods to assist or partially replace tests.Based on the validated analysis model of the aircraft dummy/seat restraint system,the significant factors affecting the response of the dummy,seat and lap belt are identified,and the technical support for the aircraft seat compliance verification by simulation analysis method is provided.Firstly,based on the sled impact tests,the dynamic response of the dummy,lap belt and seat under different impact loads are compared.Under the horizontal no-yaw 16 g impact,the peak load of the buckle side belt is severe,and the peak load on the yaw side lap seat is severe under the test condition with yaw.Under the horizontal-vertical combined impact,lumbar spine Y-direction torque of the 14g-pulse is large due to its long duration.Secondly,the dynamic response analytical model of the aircraft dummy/seat restraint system is built up and validated.The orthogonal experimental design method is mainly used to identify key factors and laws of the dynamic response of the aircraft dummy/seat restraint system.Under the horizontal no-yaw 16 g impact,the closer the Y position of lap belt anchorage is to median sagittal plane of occupant,the smaller the peak load of the lap belt is.The X-direction peak displacement of head is positively correlated with the X position of lap belt anchorage and negatively correlated with the Z position of lap belt anchorage.Under yaw 16 g impact,the yaw angle is positively correlated with the peak load of the yaw side lap seat and the X-direction peak displacement of head,and negatively correlated with the peak load of the no-yaw lap seat.Under the horizontal-vertical combined impact,the peak compression force of the lumbar spine is the biggest when the seat back angle is 111°.Finally,the front row seat impact model is built up to identify the key influence factors of the occupant injury evaluation index,and to evaluate the dynamic responses and injury levels of different brace positons for the front row seat occupants.On the upright sitting position and under the condition that the head could touch the bulkhead,the femur injury is much less than the limit value,the compression-extrude load on the neck is severe,as the distance between seat and bulkhead increases,the head injury is gradually reduced,the tibia injury is gradually aggravated,and the stiffness of bulkhead is negatively correlated with the head injury.the lap belt stiffness,X and Y position of the lap belt anchorage have no significant effect on each injury index.Under the condition that the head could touch the bulkhead,it is recommended that the front row occupant adopt the head contacting with the bulkhead brace position of the head and neck forward under emergency landing.