Discrete-continuous coupling simulation and experimental research on peak impact acceleration in falling weight-layered system collisions

Abstract

The peak impact acceleration of falling weight a_max is a key detection indicator in road engineering. To investigate the influence laws and mechanisms of layered system properties on a_max, numerical simulation combined with experimental method was applied in this study. First, the DEM-FDM coupling model for a two-layered system based on Hertz theory was constructed to study the influence of the thickness of the surface layer h, the elastic modulus of the surface layer E₁, and the elastic modulus of the support layer E₀. Then, field and model box falling weight impact experiments were conducted to verify and supplement the above results. The results show that E₁ and E₀ positively correlate with a_max under a fixed h, following a strong power function relationship. The influence of h on a_max is related to the modulus ratio. In addition, the correlations between a_max and E₁ and a_max and E₀ are highly significant, while that between a_max and h is insignificant. Furthermore, as h increases, the correlation between a_max and E₁ strengthens, while that between a_max and E₀ weakens. Moreover, a_max reflects the structural stiffness within influence depth, where E₁ is dominant. Additionally, three-layered systems in the model box can be equivalent to two-layered systems, and the above patterns in the simulation were well verified. This study provides a theoretical basis for using a_max to detect the road structural layer moduli.