Design And Verification Of Static Strength Test Scheme For Small And Medium-sized Civil Aircraft Structural Parts

Static strength testing of the structural components of new civil aircraft prior to practical application is one of the essential elements in obtaining airworthiness certification.Civil aircraft structure is complex and diverse and there is no relevant test standards and specifications.Different types of civil aircraft structural parts need to design different static strength test schemes.Small and medium-sized civil aircraft structural parts are distinguished by whether they can be tested on material testing machines,and they account for a large proportion of the civil aircraft airworthiness certification testing system.therefore,this paper takes the new civil aircraft spoiler and lug joint as typical cases of medium and small civil aircraft structural parts respectively,design and study the static test scheme according to the airworthiness requirements,and gives the design method of fixed strength test scheme applicable to small and medium civil aircraft structural parts,which is of practical significance in promoting the application of new materials and processes in the structure of civil aircraft.First,an accurate finite element model is created based on the actual working conditions of the test piece,and the results of the finite element analysis of stiffness and strength are combined,the type of material testing machine and loading requirements are initially determined for small structural parts;for medium-sized structural features,the loading scheme is initially selected and combined with the airworthiness requirements,and the design method of static strength test guidelines and test schemes for small and medium-sized civil aircraft structures is originally established.Secondly,based on the static strength test guidelines,the design of the static strength test fixture for the lug joint and the determination of the test piece assembly index were guided based on the comparative analysis of the influence of the angle deviation of the concentrated load on the loading accuracy;for the problem of applying uniform surface load to the airfoil structure,based on the principle of static equivalence,a constant surface load dispersion method is established.the loading method of the spoiler was determined as heavy load through finite element comparison analysis.The strain error at the reference point of the theoretical uniform surface loading is less than 2% under the top working condition,and the feasibility of the scheme is verified.A static test rig for spoilers was designed and machined in conjunction with the results of the finite element analysis.Finally,the test process was planned by determining the location of the four test points for each civil aircraft structural component and attaching strain gauges to the test device before the test,and measuring the angular deviation according to the assembly index to meet the index.A number of repeated static strength tests were completed,the test data recorded and the reasons for the deviations analysed,verifying that the structural components of the two new civil aircraft met the strength requirements under actual operating conditions.The above static strength test results have verified the feasibility of the design method of the static strength test scheme for small and medium-sized civil aircraft structures,providing a theoretical basis and technical support for the static strength test of similar small and medium-sized civil aircraft structural components.