Damage analysis of plastic film under hail impact

Plastic film has been widely used as one of the most important materials in various agricultural fields, due mainly to the chemical stability, thinness, and light properties. At the same time, the mechanical properties of plastic film can be the main research direction of film structure design in recent years. In this study, the experiment and numerical simulation were carried out for the damage analysis of plastic film under the hail impact. Among them, the air cannon test device was used to analyze the failure form and damage law of plastic film under hail impact. A high-speed camera and laser speed meter were then utilized to record the deformation process and energy absorption of plastic film that impacted by the ice ball. The finite element method (FEM) was also selected to evaluate the structural parameters of plastic film using ABAQUS software. The error analysis was performed on the failure area and the energy absorption of the plastic film, in order to verify the effectiveness of the numerical simulation. There was the relatively small error of the experimental and numerical simulation, indicating the better performance of the simulation. The plastic film under ice ball impact was also analyzed as follows. Firstly, the different sizes of the ice ball were selected to evaluate the impact angles of the ice ball impact plastic film. Secondly, the simulation was carried out in the the single and secondary impact of the ice ball impact on the plastic film. Finally, the ice ball impact plastic film was simulated with the different thicknesses and ice impacting double-layer plastic film with different distances between layers. The failure form and energy absorption of the plastic film were achieved in the better performance after numerical simulation. The following results were obtained: 1) The plastic film with the 0.12 mm thickness efficiently resisted the impact of hail with a diameter of less than 10 mm. Once the hail size was more than 30 mm, the plastic film was damaged rapidly, due to the action of the tensile stress wave. In addition, there was the larger damaged area that caused by the ellipsoidal hockey ball impact plastic film than that by the spherical one. 2) The secondary impact of the ice ball on the plastic film caused the superposition of stress waves, leading to the accelerated destruction of the film. 3) The largest damaged area of the film was observed, when the ice ball impact angle was 60° at the ice ball impact angle of 0°, 30° and 60°. 4) The damaged area of the double-layer film greatly increased with the increase of the distance between the plastic films. The anti-hail impact effect of the double-layer plastic film was better than that of the single-layer plastic film with the same thickness, when the distance between the double-layer plastic films was controlled within 5 mm. Therefore, the numerical simulation can be used to analyze the damage of plastic film under the impact of the ice ball. The tensile strength of plastic film can also be improved the better ability of hail impact resistance. This finding can provide a strong reference for the structural design and damage analysis of thin films.