Page 77 - 《橡塑技术与装备》英文版2026年3期

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to have good welding performance and corrosion resistance, area is 8% to 15%, which is larger than that of radial tires for
and is specially made of C9D high-quality carbon structural automobiles.
steel, with a carbon content of about 0.09%, a tensile strength For the strength calculation of the circular bead wire
of 590~610 MPa, and an elongation rate of 11.8%~13.6%. of radial aircraft tires, a new algorithm for static load safety
The outer wrapped steel wire is specially made of C82D, is adopted below, which is closer to the actual situation of
with a carbon content of about 0.82%, a tensile strength of static loading. Based on the membrane-network theory of
2,050~2,500 MPa, and an elongation rate of 6.0%~6.7%. tires, considering the deformation of the cross-section during
The use of specially selected material for the bead wire actual inflation, the increase in cross-sectional contour area
core and externally wrapped steel wire enhances the strength is calculated based on an average expansion rate of 12%.
and fatigue resistance of the bead wire, and it also boasts a As shown in figure 4, in the axial cross-section of the entire
high yield ratio, which is of great significance for optimizing radial aircraft tire and its assembled rim, the tensile force on
tire structure design. bead wire 1 (one of the four) is analyzed, and the following
2.2 Design and selection of circular bead relationship is obtained:
wire T g =P 0 ×(S A ′+S C ) = P 0 ×(K section S A +S C ) （3）
Referring to the chapter on aircraft tires in Volume 4 K section —the coefficient of increase in the axial sectional
(Tires) of the "Rubber Industry Manual", for radial aircraft area of pneumatic tires, with a value ranging from 8% to 15%;
tires, the design method of static safety multiples is currently T g — the tension of the steel wire ring, N;
adopted, with the selection of a strength safety multiple not S A′ —half of the cross-sectional area of the tire after
less than 5 times. In the formula for calculating the force on inflation, m²;
the bead wire in the manual, the inner contour area of the S A —Half of the uninflated cross-sectional area of the tire,
tire cross-section is not clearly defined as the cross-sectional m²;
area after inflation, nor is it clearly defined that the distance S C —1/4 m² of the axial cross-sectional area of the rim
between the two tire toes is the distance between the tire toes diameter and bead toe width.
after assembly on a dedicated rim. The existing calculation In the above formula, P 0 is known. The values of SA and
process can only be based on the relevant data in the uninflated SC are obtained by using relevant drawing design software
tire cross-sectional contour diagram, resulting in data errors tools to calculate the standard section dimensions and standard
and deviations in bead wire selection. rim dimensions in figure 4, respectively. This method is fast,
In figure 4, the radial aircraft tire with a circular bead wire simple, and easy to operate.
1, after being mounted on the dedicated rim 2 specified by TRA
and inflated to the rated pressure, changes its tire profile from
K to K′. The height and width of the tire cross-sectional profile
increase, changing from D to D′ and B to B′ respectively. The
carcass layer and carcass belt reinforcement layer of the radial
aircraft tire typically include any suitable cord, such as nylon
66 cord or a composite structure cord of aromatic polyamide
and nylon cord. After tire inflation, depending on the different
skeleton materials used, the expansion rate of the cross-
sectional width ranges from 1% to 10%, and the expansion rate
of the outer contour diameter ranges from 0% to 7.5%. The
area shown in region A´ in figure 4 is the axial cross-sectional
area of the tire after inflation, and the illustration shows a
Figure 4 Cross-sectional view of radial aircraft tire
quarter of the area. The growth rate of the tire cross-sectional

Vol.52，2026 ·31·