Research On Impact Failure Of Windshield Laminated Glass And Head Injury Of Pedestrian

Automotive windshield glazing is a simple sandwich composite material,comprising of two layers of soda-lime glass and an interlayer of polymer which are bonded under vacuum and high pressure environment.In the head-on collision between a pedestrian and a vehicle,the head of the pedestrian might hit the area of the windshield,and the pedestrian safety may be threatened.During the process of producing windshield glass,reducing the damage of pedestrians' heads from hitting and the harm caused by glass shattering due to the PVB-glass debonding should be considered.Therefore,it is important to investigate the impact performance of windshield laminated glass and the damage on pedestrians' heads under impacts.Scholars often use the experimental method,the numerical method and the theoretical method to study the impact process of windshield.This paper investigates the dynamic process of windshield under the impact of head model through the method of intrinsic cohesive force and discusses the damage law of the human head numerical model when impacting with the windshield glass.First of all,the bilinear cohesive zone model is employed to describe the fracture problem.The zero-thickness cohesive elements are adaptively inserted on the common surfaces of finite elements via program code.Both of the fracture behavior of glass and the adhesive behavior between glass-PVB interfaces are performed by the constitutive relations of cohesive zone model.Thus,the intrinsic cohesive windshield model is preliminarily established.After that,the impact process between head model and windshield is simulated according to the EEVC standard.The simulation results of acceleration history and the glass fracture patterns are contrasted with corresponding experimental records,and the validity of the intrinsic cohesive windshield model is verified.Furthermore,the change rule of the impact force,the acceleration,the HIC value,the kinetic energy of head model and the internal energy as well as the damage energy of each structures of windshield laminated glass is discussed under different conditions of interfacial bonding,PVB material,impact velocity and impact angle.In the end,the human head model is built,and then validated against the Nahum's head impact test.This human head model is used to impact the intrinsic cohesive windshield model to simulate the whole impact process of the windshield subject to pedestrian's head.Besides,the change rule of the pedestrians' head injury symptoms,including the skull fracture,cerebral contusions,the SAH/SDH and DAI,is discussed under different impact conditions in terms of impact velocity,impact position of windshield and human head contact position.