Detection Probability And Inspection Test Of Dents For Composite Laminates

The detection probability of visual inspection is not only an important basis for aircraft structural design,but also the basis for formulating specific visual inspection methods and structural maintenance plans.Therefore,in accordance with the requirements of airworthiness regulations,in the operational compliance review of civil aircraft,it is necessary to conduct experimental research on the visual inspection factors and the detection probability of structural damage,especially the damage of structural surface dents.In this paper,a visual inspection test of dent damage of composite laminates has been carried out.The effects of various influencing factors(surface color of test piece,placement angle,whether the surface is reflective,the professionalism of the inspector,etc.)on the visual inspection results were investigated.The results of test were recorded by placing the colored suckers beside the dents and saved the results with photos.More than 19,000 photos were obtained in all experiments,and 18,100 final effective photos were obtained.In order to accurately count the results of the visual inspection of composite material laminate dent damage and determine the detection probability of the dent damage visual inspection,based on the characteristics of the detected damage in the photo with marked suckers,an identification method of dent damage detection based on color feature and distance is proposed.The results show that this method can ensure that the recognition rate of dent damage detection exceeds 99.95%,and the computer program is simple to implement,and the workload of image analysis is small.It is suitable for large-scale data processing.The cumulative log-normal model is used to evaluate the detection probability of dent damage by visual inspection of different influencing factors.On this basis,the threshold range of the dent damage detection for professional general visual inspection(GVI)and detailed inspection(DET)is given.The conclusions considering different influencing factors are as follows:(1)Compared with the white test piece,the green and blue test pieces have a higher probability of detecting dent damage;(2)Professionals with relevant experience in maintenance or visual inspection have a higher probability of detecting dent damage;(3)For white,blue and green test pieces,the smaller the angle between the test piece placement angle and the vertical plane,the easier it is to detect dent damage;(4)Comparing the two visual inspection methods,the detection probability of dent damage in the detailed inspection(DET)is higher;(5)The detection probability of dent damage in the indoor test piece reflective condition and outdoor cloudy day is higher than that of the indoor test piece without reflection.