Composite Reinforced Structure Distributed Fiber Static Load And Impact Monitoring Technology

Composite stiffened laminated plate structure is one of the most effective methods to improve the overall stability of laminated plate,and it is more and more widely used in the design of aerospace structures.However,during the manufacture and use of the structure,due to imperfect manufacturing processes or the impact of foreign objects,layered damage and failure are prone to occur,which reduces the bearing capacity of the structure.The fiber Bragg grating sensor has the unique advantages of light weight,anti-electromagnetic interference,high sensitivity,and easy distributed networking.It is very suitable for the structural and health monitoring of aerospace vehicles in complex and harsh environments.To this end,this paper proposes to study the impact monitoring technology of composite stiffened plate structures based on fiber Bragg grating sensors.The main work includes the following aspects:Firstly,the mechanical modeling and analysis of the dynamic and static response characteristics of the four-side clamped composite stiffened plate were carried out.A threedimensional mechanical model of a stiffened composite plate was established using ABAQUS finite element simulation software,and the strain distribution and response law of the stiffened plate structure under static load and impact conditions were obtained through numerical simulation.On this basis,based on the results of finite element simulation,the feasibility of the strain field inversion and impact location algorithm based on the distance reciprocal multiplication method is verified.Secondly,the dynamic and static response characteristics of fiber Bragg grating sensors based on four-sided clamped composite stiffened plates are studied.By means of experiments,the influence characteristics of different loading distances,loading angles,load sizes and rib positions on the sensor’s center wavelength offset,impact response energy amplitude,strain distribution,and strain transmission effect were obtained.On this basis,the effective monitoring area coverage corresponding to different fiber Bragg grating sensor layout schemes is calculated.Thirdly,based on the principle of identification of strain field abrupt change,a method for distributed load and impact location of distributed optical fibers with four-sided clamped composite plates is proposed.A strain field inversion test system for composite plates based on the distance reciprocal multiplication method principle was constructed.The dynamic strain and static load positions were obtained by identifying the characteristics of the local strain abrupt change of the plate caused by static loading and impact.Finally,a method of impact monitoring and position identification of composite stiffened strips based on fiber Bragg grating sensors was studied.With the help of a laser Doppler vibrometer,the transient response characteristics of a stiffened plate corresponding to a plate impact and a rib impact are obtained,respectively.On this basis,the preliminary identification of the impact position of the stiffened ribs is realized.