Theoretic Modeling And Experimental Analysis Of Non-Linear Shock Characteristics Of Rubber Isolator

In order to adapt to the modern warfare nowadays, the naval warship equipped with many mechanical and electronic equipments. These equipments have to been protected and insulated from the shock damage. Therefore, the anti-shock isolators should have enough elastic displacement deformation and damping, which means that use the non-linear anti-shock isolators can achieve the better shock isolation effect.Along with the advancement of new experimental equipment, drop weight method,frequency sweeping method and other experimental measure were widely used to determine impact responsive characteristics and the stiffness of nonlinear isolator. Besides, the fast development of finite element theory as well as finite element process software provided numerical modeling resolution for researchers to solve impact response hypothetically. However, due to strong nonlinearity of stiffness and dampness, it was hard to choose a numerical or theoretical model for resolution, or to identify the parameters of the modeling. This research composes of six chapters as follows.In Chapter 1, presented at first is the background of this research and the latest development of anti-shock research development.In Chapter 2, a brief introduction of the forms and characteristics of underwater impact was presented, a comparison between vibration isolation and shock isolation was analyzed in detail. Several typical nonlinear isolators were presented, including stiffness characteristics and a typical calculation method for shock response. Then examples of typical nonlinear isolators were outlined to discuss advantages and disadvantages.In Chapter 3, hyper-elastic constitutive equation and visco-elastic constitutive equation were outlined in detail on rubber isolator. What is more, force-displacement hysteretic model theory was presented with typical double-line model manifestation. Base on Pan-Yang mathematic hysteretic model, a force-displacement hysteretic model characterized by eight parameters was brought up.In Chapter 4, as the main method at home and abroad, the drop weight impact testing method is widely accepted by navies. This chapter gave two drop weight impact test methods. The first is the Regulated Impact Velocity Method(RIVM), which limits the impact velocity. T he second is the Regulated Impact Wave Method(RIWM), which regulates the impact wave based on the impact wave generator. During the experiment, RIWM method was implemented to obtain the impact characteristics of shock isolator. The F-S shape of the isolator in the test result is consistent with the 8-parameters model's prediction.In Chapter 5, base on the viscoelastic and hyperelastic theory in chapter 2, a hyper-viscoelastic constitutive relation of integral form was used to describe the rate-dependent material behavior of the rubber. The proposed constitutive equation was implemented in ANSYS via a user-defined subroutine and was used to predict the shock response of the rubber isolator in the experiment. LMM method was use to implement acceleration input on the base of isolator to monitor real-time environment.In Chapter 6, conclusions of this thesis are summarized, comparison between these two methods was discussed and further work is suggested.