Analytical determination of static and dynamic elastic characteristics of pneumohydraulic suspension systems

When developing new suspensions for tracked and wheeled vehicles, as well as in the so-called reverse engineering of existing structures (including in the educational process of training personnel), it is necessary to solve the problem of finding the elastic characteristics of the suspension. In the first case, it is necessary to ensure the fulfillment of the specified tactical and technical requirements, in the second - to restore the form of characteristics according to a known design. Both of these tasks are greatly complicated in the absence of precise and universal analytical dependencies suitable for determining the characteristics of elastic suspension elements of various design implementations. The experience of interaction with some factories shows that designers, not being able to qualitatively calculate the elastic characteristics, use the method of selection and analogy, when for a new vehicle they use the suspension as on the old one, scaling it in size in order to approximately keep the values of working pressures. The numerous bench tests are carried out, which results are used for selecting required charging volume and pressure. Suspensions with backpressure cause particular difficulty, since not only the final characteristic, but also the performance of the entire unit depends on the combination of volumes and pressures of the two chambers, which work in antiphase: when one is loaded, the other is unloaded, and vice versa. Using analytical dependencies will reduce the time spent on design, to parameterize, to a certain extent, the suspension kinematics, to obtain the values of the equivalent suspension stiffness, and also to be able to develop the characteristics of the model range of pneumohydraulic springs for vehicles of various weight categories.

This article presents a technique for the analytical determination of the characteristics of pneumohydraulic springs of various designs. The options include both actually used in modern and historical technology (in particular, on BMD-1, 2, 3, 4; GM-352; Ural Typhoon; Object 775, etc.), and obtained by combining various structural elements, which implementation can be useful in the educational process in training personnel. The dependences presented in the article make it possible to obtain static and dynamic elastic characteristics at various polytropic indices and are suitable for the design of suspensions for wheeled and tracked vehicles for various purposes.