Research on cord-laying angle and mechanical balance of rolling lobe air springs

Abstract

The inflation of the rubber bellow leads to flexion and deformation during the operational process. The cord, serving as the primary load-bearing element of the rubber bellow in air springs, undergoes continuous changes in angle due to bending, torsion, and internal stress and moment within the bellow. This alteration causes the resultant force on the cord to deviate from its original direction, disrupting the force balance of the bellow and subsequently diminishing its fatigue life. To identify an optimal cord-laying angle that minimizes deviation from the cord's direction under the resulting force during operation, a theoretical model is established for the rubber bellow in rolling lobe air springs. This model is based on thin shell momentless theory and a force analysis of bellow micro-elements. The mapping relationship between the inflated cord angle and the uninflated cord-laying angle is examined. Furthermore, the dynamic variation of the cord angle along the longitudinal direction after the inflation of the rubber bellow is explored in this article. Additionally, a novel indirect measurement method for determining the outer diameter of the bellow is proposed to acquire the cord angle. This method is employed to verify the validity of the optimal cord-laying angle and the finite element model. The results indicate that the optimal setting interval Y for the cord-laying angle of sample A is [45°, 47°]. This finding not only offers theoretical support for the forming process of rubber bellows in rolling lobe air springs and the optimization of bellow characteristics but also introduces a new approach for measuring cord angle variations.