# Scaled Experiment of the Detonation Control System for the High-Speed Penetration on Concrete
## 3 Parameter Analysis of the Deceleration
### The Compressive Strength of the Target  
It can be seen from Section 3.1 that independent and effective parameters for the concrete material that affect the deceleration are the density and the compressive strength. However, the density with different strength varies little, and its effect on deceleration is very weak. Different compressive strength has a significant impact on the deceleration, so the compressive strength as the main parameter is analyzed by the FE simulations.  
According to the ogive-nosed projectile with \(\varphi=3\) and the structure of the detonation control system in Figure 2, the FE model of the projectile is established. In the FE simulations, the compressive strength of the concrete target is 20 MPa, 30 MPa and 40 MPa. The deceleration peak and time history of the detonation control system can be read in Figures 5 and 6. Figure 5 shows the influence of the compressive strength with different geometric parameters of projectile under the constant impact velocity. Figure 6 shows the influence of the compressive strength with different impact velocities. In general, the stronger the concrete is, the higher the deceleration peak is. By using the ogive-nosed projectile, concrete targets of different compressive strength can basically make the deceleration peak on the \(10^{4}\) orders of magnitude. It should be noted that when the concrete strength is 20 MPa, the deceleration peak may be less than 10,000 g due to the limitation of the impact velocity or the projectile size. The deceleration peak can be further improved by reducing the mass of the projectile. In addition, choosing the concrete with lower strength is used to have a long time history. So, when selecting the concrete as a target material in the laboratory-scaled experiment, priority is given to low-strength concrete to obtain a long time history.  
experiment in the laboratory to improve the repeatability of the experiment, so the impact velocity is controlled in a limited range. The single stage gasgun is widely used and cheaper [28]. The impact velocity can be adjusted in the limited low-speed range, and the single stage gasgun usually provides an impact velocity of 200-300 m/s.  
In the FE simulation, the ogive-nosed projectile is applied with different impact velocities (200 m/s, 250 m/s, 300 m/s and 350 m/s) to penetrate the concrete targets, and deceleration peaks and time histories at different impact velocities are obtained. The simulation results can prove that the impact velocity has a very obvious impact on the time history and the deceleration, as shown in Figure 6. It can be seen from the peak trend of the deceleration that the change of the impact velocity between 250 m/s and 300 m/s is the most significant for the deceleration peak. When the impact speed is 300 m/s and the concrete with different strength is chosen as the target, the deceleration peak is more than 10,000 g. The higher the impact velocity is, the longer the time history is.  
The faster the impact velocity is, the higher the requirements for the launcher in the laboratory are. The projectile models used in the simulations are all solid, and it is difficult for the single stage gasgun to provide these ogive-nosed projectiles with an impact velocity of more than 350 m/s. However, the actual design of the projectile is not a solid structure, and the actual mass will be less than that of the simulation model. The peak and time history of deceleration will be higher than the simulation results. Therefore, the impact velocity is a restrictive condition in the laboratory-scaled experiments, because it can only be adjusted within a limited range.