The conical spring, characterized by its high flexibility and substantial deformation
during operation, presents challenges for conventional engineering theories. Existing
dense and sparse coil spring theories are limited to small deformation calculations of
conical springs, lacking a comprehensive understanding of spring flexibility under
significant deformation. Addressing this gap, this paper derives a nonlinear flexibility
expression for the large deformation of a conical spring, accounting for the
impact of the pitch angle based on the interrelations of parameters in a
constant pitch conical spring. Geometric nonlinearity calculations under
conditions of substantial deformation are conducted using finite element
simulation software. The results demonstrate a close alignment between
the expression proposed in this study and finite element outcomes, with a
deviation of less than 3%. Conversely, sparse coil spring theory aligns with finite
element results only under conditions of minor deformation, with increasing
disparities as deformation intensifies. The validated nonlinear flexibility expression
presented in this study serves as a pivotal reference for engineering applications,
offering valuable insights for the design and utilization of springs in practical
scenarios.