# Ground Simulation Tests in Two-Dimensional Dynamic Acceleration Environment
## 1 Introduction  
Acceleration environment (AE) can generate accelerated environmental forces by means of simulation tests, which is used for performance testing and reliability experiments. AE has been widely applied in various areas such as aviation, space, environmental medicine [1], medical science [2], biomedicine [3], materials [4], and acceleration sensors [5]. The acceleration process of aircraft includes two stages: launch and maneuvering flight. The AE of aircraft is usually evaluated by the axial acceleration and the radial acceleration. The greater the axial acceleration is, the faster the speed change of the aircraft will be. The greater the radial acceleration is, the better the maneuverability of the aircraft will be. To perform ground-based tests of the acceleration sustaining ability of aircraft's inertia device and aerospace materials and to verify the strength and reliability of the system, it is necessary to investigate ground simulation test methods of two-dimensional (2-D) dynamic AE. An aircraft ground simulation test usually uses a centrifuge to emulate a sustained AE. [PERSON] et al. [6] studied the control algorithm of a centrifuge motion simulator for pilot training. The simulator could simulate acceleration forces that act on aircraft pilots through rotations about axes. [PERSON] et al. [7] used accelerated centrifugal force to simulate G-forces during aerial combat, and studiedstress-influence factors in the centrifugal training for military aircrews. But the centrifuge cannot realize the synchronous controllable loading of 2-D dynamic acceleration, so it is unable to simulate a flight AE. A composite system of a centrifuge and a test turntable can simulate the flight AE. Test turntable is an important equipment for research on inertia components and has been widely utilized in aerospace [8]. [PERSON] et al. [9] used a double turntable centrifuge (DTC) to test rectification error due to the composite accelerations. The DTC was utilized to produce the constant acceleration and vibration simultaneously. However, the composite system cannot be started instantaneously, thereby failing to simulate an impact AE during the launch phase. In general, a typical dynamic impact simulation device is composed of a Hopkinson bar, a drop tower, a centrifuge, and an air cannon. The live-fire tests include artillery launches and air drops. The acceleration amplitude, pulse width, and frequency characteristics generated by each acceleration simulation test method vary, so the application scope of each method is different. Through using impact loading tests to simulate the stress environments, the strain characteristics and impact resistances of materials can be studied. [PERSON] et al. [10] analyzed the performance of wafer-level chips by using board-level drop impacts to produce accelerations between 10,000 \(g\) to 30,000 \(g\) with multiple impacts at the impact point, and the acceleration amplitude and mounting clearance were varied. By modifying [PERSON]'s theory and optimizing the experimental models and parameter evaluation [11], [PERSON]'s rod experiments have achieved a high range of strain rates. Furthermore, [PERSON]'s rod experiments are simple, efficient, and reproducible, which become a common method of investigating material properties under high-strain-rate impact loads [12]. [PERSON] and [PERSON] [13] proposed a specific thermo-hyperplastic constitutive model function to examine the performances of corresponding materials and numerically simulated the [PERSON] impact test. [PERSON] et al. [14] designed a Hopkinson bar calibration device and studied a dynamic linear calibration method for high-\(g\) accelerometers. Using high-pressure gas as the power source and controlling the air pressure, an air cannon controlled the launch acceleration. Using the air cannon to assist the loading, it became possible to simulate a high acceleration load environment and the explosion impact environment, thereby allowing environmental testing on the structures of spacecraft and instrumentation.