Test Method And Experimental Research On Mechanical Properties Of CFRP Under Complex Working Conditions

As one of the advanced composite materials,carbon fiber reinforced polymer(CFRP)is widely used in aerospace,automobile,ship,civil engineering,environmental energy saving,sports and other fields because of its outstanding characteristics of high strength,high modulus,light weight,and many advantages such as no rust,good chemical / thermal stability.Therefore,it is necessary to have a comprehensive and detailed understanding of its mechanical properties.At present,the testing of mechanical properties of CFRP at home and abroad focuses on the single load test.However,in the course of service,the materials are often subject to one or more mechanical load combinations,which involve the coupling of physical fields such as temperature,humidity,electric field or magnetic field.Because of the distinct anisotropy of CFRP,the mechanical response in different directions and different load forms has obvious differences.and single load test is not enough to meet the test requirements of CFRP under complex working conditions.Therefore,it is very important to carry out the test method and experimental research on the mechanical properties of CFRP under complex working conditions.In this paper,by summarizing and analyzing the research status of mechanical properties testing technology and composite load material testing technology of CFRP composite material at home and abroad,the significance of the research content in the current application environment of CFRP is clarified;the self-made testing device is briefly introduced,and the main components are defined in the coordinate system.Based on the phase correlation method and Canny edge detection algorithm,the problem of alignment between 6-DOF platform and 6-D force sensor coordinate system is solved.Through reasonable structure design,the problem of alignment between force sensor and upper/lower fixture coordinate system is solved.At the same time,the correction matrix of force and moment is given according to the error caused by the change of space position of 6-D force sensor during loading.Aiming at the problem of composite load in material test,the control scheme of feed-forward BP neural network is selected,the original data needed for training network is completed by the composite load test of tension-cantilever bending,and the optimal parameter combination of BP neural network is obtained by the theory and method of orthogonal test design.Finally,the effectiveness of the control scheme is verified by the actual test.Based on the test requirements,the specimen was redesigned,an efficient speckle preparation method was determined,and the test was reasonably planned and designed.The mechanical properties of CFRP under single load and composite load are tested.The influence of load form,load combination form and loading sequence on the mechanical properties of the specimen is preliminarily explored.