Finite Element Simulation And Static Strength Check Of A Navigation Aircraft Flap

In this paper,the flap of a single-engine four-seat fixed-wing navigable aircraft is taken as the research object,and the general method and process of finite element modeling and static strength checking of aircraft structure are studied through the combination of finite element simulation and engineering algorithm calculation.The structural static strength of the initial design of the flap is checked,and it can be the theoretical basis for the optimization design of the aircraft and the airworthiness validation of the aircraft.Firstly,the geometric model of the flap is pruned and simplified.The modeling method of finite element model for flaps is studied,including structural simplification,meshing,structural material properties,constraint conditions and loading.The load and stress results of the flap's structure under the limit load which required for the static strength are obtained by finite element simulation,including the stress distribution of the structures,the interaction between the structure and the external support reaction to the structure.Then,the stress characteristics of each component of the flap are analyzed,and the key structure and main contents of static strength check are defined.The engineering algorithm of critical stress(load)of typical aircraft structures is studied in detail.According to the geometric size and constraint conditions of each flap structure,the critical stress and critical load of each structure are calculated by the engineering algorithm.The extraction method and principle of finite element simulation results for static strength checking are studied in detail.The critical stress calculated by engineering algorithm is compared with the results of finite element simulation,then the margin of safety(MS)of each component of flap under the limit load is obtained.In this paper,the rivet load distribution engineering algorithm of eccentric connection is summarized,and the theoretical calculation formula of rivet load distribution of eccentric connection is obtained.Taking the rotating joint lug of the flap as the research object,the rivet load distribution of the eccentric connection is calculated by theoretical calculation and finite element simulation,and the distribution law is verified by experiments.Finally,based on the results of static strength check,an optimal design scheme is proposed for the subsequent lightweight design of the flap,which can reduce the weight of the flap while ensuring the static strength.The results show that,(1)The margin of safety of the key structure of the flap isgreater than 0,and all the structures meet the static strength requirement.The margin of safety of shearing instability of skin is the smallest,its MS is 1.4,and the margin of safety of inter-rivet buckling is the smallest of spar,its MS is 3.90;and the margin of safety of pin bending failure is the smallest of connector,its MS is 3.98;and the margin of safety of extrusion yield is the smallest of rivet,its MS is 4.75.(2)The results of rivet load distribution calculated by the theoretical formula of eccentricity connection have high similarity with the results of finite element simulation.The rivet with maximum load and its load can be obtained accurately by both methods,and the experimental results show that the rivet load distribution of eccentric connections is consistent with the theoretical calculation and finite element simulation,and the smallest margin of safety of rivet is 3.31 in eccentric connections.(3)The optimal design scheme can reduce the structural weight of the flap to a certain extent.But at the same time it also reduces the margin of safety of the structure.The optimization effect of the skin is the best,the rib is the second,and the optimization effect of the spar is the worst.