Papers by Author: Hai Huang

Abstract: An improved controller based on ADRC is proposed for motion control with high frequency disturbance. Firstly, relationship between bandwidth of LESO and its parameters was mentioned, and bandwidth limitation come from the sensor noise is presented, indicating weakness of traditional LESO on compensation high frequency disturbance. Based on such analysis, two FIR filters is designed and added into the control loop, which compensated the specified high frequency disturbance and expanded bandwidth of LESO, acquiring a better motion control result. Simulations are taken, showing validity of the improved controller.

Abstract: For the multidisciplinary design optimization (MDO) question of autonomous rendezvous spacecraft, first, the analysis model and coupling relations of payload, propulsion and structure discipline are discussed; then the updated analytical target cascading (UATC) method is introduced and compared with the widely used collaborative optimization (CO). Results prove that the UATC method requires 54.8% fewer average subspace iterations than the CO and is more efficient for practical engineering MDO problem. Finally, based on the UATC method, a MDO problem of autonomous rendezvous spacecraft is solved and gets reasonable and effective results. The process proves the effectiveness of UATC method solving spacecraft MDO problem.

Abstract: For coiled flexible shells, theoretical formulas of calculating the stress distribution are derived and applied to initialize the prestressed status of the shells before deploying. Following the prestress initialization, dynamic simulation of elastic and elasto-plastic deployment processes with large deflections of the shells is conducted by explicit time integration. It is shown that the simulation based on prestress initialization method is feasible and efficient. Comparing the deforming process and the energy history of the elastic deployment with that of the elasto-plastic deployment, the effects of plasticity are embodied as slowing the deployment process down and speeding the kinetic energy dissipation up, while making the shell unable to return to its original configuration, and keep more residual strain energy. A primary approach to decrease the effects of plasticity is improving the initial prestressed status of the coiled flexible shells.

Abstract: A method for material fragmentation based on Lagrangian FEM with the concept of nodes separation is proposed. This method is consisted of nodes separation mechanism and elements distortion erosion. In the simulation the nodes of failure elements are separated to form crack and distorted elements are detected and eliminated to prevent singularity. Nodes separation method can greatly improve the energy loss disadvantage in the failure erosion method. Based on LS-dyna secondary development the method is implemented. Hypervelocity impact problem of satellite protective structure is simulated and compared to experimental data for calibration. The performance of multi layer aluminum mesh shield under hypervelocity impact is also evaluated. The results show the high efficiency and applicability of nodes separation method in practical problems.

Abstract: Non-plane joints, such as T-joints, L-joints and  shaped joint can bring enormous potential benefits from the reduction of the fastener and the part count, which lead to the dramatic decrease of assemble cost and primary structural weight in composite structures. To understand the mechanistic character of the  joint, a 3-D finite element analysis model is established by means of software ABAQUS. The stresses on ply level and the predictions on the damage onset of 3-D woven composite π joint under tensile load are obtained. Numerical results agree well with empirical data. The effects of structural geometry parameters, such as support length, support thickness and radius of the corner, are also discussed. Results illustrated that increasing the thickness of L preform or filler radius can improve the strength of woven composite π joint effectively.