Impact Dynamic Analysis and Rubber Impact-Resistant Design of a Launcher

Abstract

To study the influence of the opening process of a naval ship’s weapon launcher on the local strength of the impact-resistant structure, the load and inherent characteristics of the system were analyzed, a finite element dynamic model and theoretical Kelvin–Voigt single degree of the freedom system model were established, the dynamic response properties of the impact-resistant structure under an impact load were studied, and the impact spectrum of the system at different impact load durations was obtained. The results indicated that the first-order vibration period of the impact-resistant structure was much shorter than the impact load duration, and the dynamic amplification coefficient of the system was close to 1. Consequently, a theoretical model of a single degree of the freedom system was established, while the analytically derived displacement spectrum was consistent with the finite element calculation results. Therefore, the dynamic strength check of this impact-resistant structure could be treated as a static problem. According to the static calculation, the maximum stress of the structure occurred at the root of the base, which was 188.3 MPa, exceeds 0.3 times of the material yield stress specified in the military standard. To meet the military standard, a simplified collision model was established with the thickness of the rubber pad as the reference variable, the combined force on the bottom surface of the rubber pad was extracted, and the resulting equivalent displacement was calculated according to Hooke’s law. The range of the rubber pad thickness was determined as 11.6 mm < d < 12.5 mm to meet the military standard and not affect the normal firing of the weapon.

Study on the Dynamic Properties of Concrete under Freeze-Thaw Cycles and CT Fine View Damage

“…Fan et al [12] found that the compressive and fexural properties of specimens were decreased with freezethaw cycle in their study of the durability of rubberized concrete under freeze-thaw cycle. Zhang [13] investigated the dynamic mechanical properties of the rubber concrete under diferent number of freeze-thaw cycles and impact air pressure and found that the freeze-thaw action destroys the rubber concrete, and there is a signifcant strain rate efect on its dynamic parameters. Freeze-thaw cycle will have a deterioration efect on the mechanical properties of concrete, and some scholars have characterized the degree of damage from a macroscopic point of view.…”