Determining regularities of the stressed-strained state of flexible shell of the pneumatic spring made of polymeric material

Abstract

Pneumatic springs make it possible to implement the «soft» characteristics of the suspension of vehicles, which provides comfortable conditions for passengers and reduces the dynamic load on the road surface. The issue of the strength of the flexible shells of pneumatic springs, which are made of rubber cord, remains relevant. Strains that stretch flexible shells, which arise in the process of movement, cause ruptures of rubber cord, thereby reducing their reliability. At present, there is a global tendency to replace rubber cord with polymeric materials. This paper reports a study of the strength of a two-sided flexible shell of the cylinder type under different operational modes of a pneumatic spring. The research was carried out using a finite-element method. The peculiarity of the pneumatic spring design is that the diameters of the bottoms and inter-corrugation ring are increased to the size of the outer diameter of the flexible shell in order to improve the stability and damping properties of the pneumatic suspension. The flexible pneumatic spring shell is made of polymeric material. It is proved that the stress in the material of the flexible shell increases in proportion to the air pressure in its cavity; their greatest values are observed in places where the flexible shell is fixed to the bottoms. When approaching the equator of the shell, they gradually decrease by an average of 20 % in both corrugations. The increase in the radius of the equator in both corrugations of the flexible shell did not exceed 20 mm. With a mutual transverse displacement of the bottoms by 40 mm and excessive air pressure of 0.5 and 1.0 MPa, the stress in the flexible shell material was 2.9 MPa and 5.9 MPa, respectively. This is almost five times less than the strength limit of the material for breaking (30 MPa). Thus, the selected parameters ensure the strength of the flexible pneumatic spring shell: it can be recommended for use on vehicles

The stiffness of elastomeric diaphragm in pneumatic springs

“…Xu [15] divided the diaphragm into four segments, and each segment was simplified as a unidirectional stretching elastomer, then the diaphragm's equivalent stiffness was calculated by the series-parallel combination of four segments. Lee [16], Masliyev [17] and Vo [18] studied the stiffness characteristic using the finite element method (FEM). However, after experimental or FEM modification, there is still a significant error between the actual and the proposed model value, in addition, the experimental or FEM modification is inconvenient for the parameter optimization design of pneumatic springs.…”