Due to the complex form and long duration of the load from a confined explosion, it is usually difficult to propose an uniform simplified formula to describe the confined blast load effectively, which can be applied in the predicting the dynamic response of structures. In present paper, the explicit dynamic code Autodyn was employed to predict the response of steel plates under confined blast load numerically. The effectiveness of the numerical method was validated by comparing the numerical and experimental results, and then the characteristic of saturated impulse of steel plate was analyzed. The numerical simulations of 216 plates, which experience different load durations, were conducted. Based on analyzing the relationship between the duration of confined blast load and the subsequent dynamic response of these steel plates, a simplified formula was deduced to determine the saturated time that corresponding to the maximum deformation of plate, and a guide value of the parameter of the dimensionless saturated time was presented. Considering the influence of initial shock wave of confined explosion, combined with the law of saturation action time of explosion load, a rectangular load equivalent method for the confined blast load is proposed. The dynamic response of metal plate under 18 groups of simplified and fully-coupling load is compared, and the effectiveness of the equivalent method is verified.
Explosion and Shock Waves