Determination of mechanical performance of air suspension bellows for vehicles in confection process using symmetric ply method

This study aims to develop an innovative approach called the "Symmetric Ply Method" for the manufacturing process of air suspension bellows used in vehicles and to comprehensively evaluate the effects of this method on mechanical performance. Air voids frequently encountered between layers in conventional tire winding processes negatively affect product quality, reducing the durability and lifespan of the bellows. To address this issue, the symmetric ply method involves cutting the second and third layers of rubber-coated cord fabric into different widths to create a stepped structure, thereby minimizing air gaps between layers. In the study, multi-faceted experimental tests such as tensile, rupture, burst, load, and growth tests were conducted on bellows produced by the symmetric ply method and those produced by the conventional method. Additionally, dynamic mechanical analysis (DMA) tests were performed to reveal the viscoelastic properties of the material. Parallel to the experimental data, numerical analyses of pressure-dependent deformations, force distribution, and stress values of the bellows were carried out using the finite element method (FEM) with Abaqus software. Thus, the effects of the symmetric ply method on mechanical performance were validated both experimentally and numerically. To increase efficiency in the production line, a new system called the "double ply servicer," capable of carrying two different sizes of cord fabric bobbins, was designed, and its manufacturing processes and feasibility analyses were conducted. This design provided flexibility and capacity increase in the production line, contributing to the optimization of manufacturing processes. The research results demonstrate that the symmetric ply method provides significant improvements in both product performance and production processes. This method reduces air voids between layers, enhances the mechanical durability of the bellows, increases production efficiency, and supports the competitiveness of the Turkish automotive sector. The study serves as an important reference for the integration of innovative manufacturing techniques developed with domestic resources into sectoral applications. Keywords: Air suspension bellows, Symmetric ply method, Dynamic mechanical analysis (DMA), Finite element analysis (FEM), Double ply servicer, Mechanical performance