## 4 Experimental Study on the Dynamic Performance of Hydraulic Supports  
To investigate the dynamic performance of the support, a support performance testing system was constructed. Corresponding to the simulation process, the unit support was simplified, and a prototype of the unit support was fabricated at a 1:3 scale, with the basic parameters of the support prototype. The dynamic experimental study of the hydraulic unit support coupled with the roof mainly investigates the variation in displacement and pressure parameters at various collection points on the top beam and column cylinders of the hydraulic unit support prototype under the excitation of a hydraulic actuator in a supported state. The sensor layout of this experimental setup is depicted in Figure 12. Two laser displacement sensors are mounted on an independent wooden support structure, which is anchored to the ground and separate from the experimental platform. Test point 1 is positioned at the base of the intermediate beam, while test point 2 is situated at the base of the side beam. Two pressure transducers are connected in parallel on the pipeline of the support prototype's columns to separately measure the oil pressure in the rod cavities of the left and right columns of the support prototype. Figure 11: Bearing conditions at the hinge between the top beam and the column under different working conditions: (**a**) stress variation; (**b**) displacement variation. Since the hydraulic system of this experimental platform shares the same hydraulic power unit, in order to ensure the stability of the support structure, the internal and external loading should be carried out independently when applying loads to the hydraulic support. During loading, the hydraulic unit support is first preloaded. Subsequently, vibration loading is applied to the servo valve. When the support prototype is excited by a uniformly distributed dynamic load, it moves smoothly with relatively low vibration signals. The range of displacement amplitude is 0-20 mm as shown in Figure 13, and the range of column oil pressure amplitude is 5-35 MPa, as shown in Figure 14. When the support prototype is subjected to concentrated dynamic load excitation, the vibration signals are relatively strong. The range of displacement amplitude is 4-17 mm, and the range of column oil pressure amplitude is 20-30 MPa. When the support prototype is excited by dynamic eccentric loads, the vibration signals are pronounced. The range of displacement amplitude is 4-18 mm, and the range of column oil pressure amplitude is 16-30 MPa. When the support prototype is subjected to dynamic torsional load excitation, the vibration signals are relatively weak. The range of displacement amplitude is 2-12 mm, and the range of column oil pressure amplitude is 22-29 MPa. Figure 12: Hydraulic unit support experimental prototype. Figure 13: Displacement of measuring point of top beam: (**a**) test point 1; (**b**) test point 2. Differences between experimental and simulation results may stem from several factors. First, hinge joints in practice might be loose or gapped, leading to boundary conditions that do not fully match simulation assumptions. Simulations often presume fully fixed constraints, but actual constraints in experiments may be less rigid. Second, contact nonlinearities can occur in experiments, and geometric nonlinearities at large deformations can significantly impact results, effects that simulations might not account for. These factors can result in discrepancies between the two. However, the overall dynamic response is still favorable, with the dynamic response of the support's top beam under excitatory loads aligning well with experimental findings. Through comparative experiments, it has been observed that under the influence of dynamic excitation forces, vibration signals at critical parts of the support prototype are pronounced.