Rolled plastic film damage simulation considering surface roughness useful for greenhouse roof automatic ventilation

Greenhouses are capable of producing a variety of high-value crops year-round. A novel Japanese greenhouse design is gaining popularity because of its automated rolled-up ventilation system that is integrated into the roof. However, due to the frequent movement of the roll-up system, the plastic film deteriorates rapidly and typically lasts for only three or four months. In order to better understand the film deterioration, we studied the mechanics involved at the point of contact between the film and the metal greenhouse frame. We found that film deformation and failure were closely related to stretching and creasing, and these processes were observed at the microscope level. In this paper, the plastic film damage was investigated through the rolling contact analysis focusing on the pipe surface roughness. We found that at the inside film surface the larger strain is caused by the pipe surface roughness. This larger strain generates the wave deformation of the film, crease and line scar whose number increases with increasing the roughness of the arch pipe. The effects of pipe coating and perforated film are discussed to prevent the film damage. (paper)