Research On Mechanical Properties Of Honeycomb Cores Based On Image Measurement

Honeycomb sandwich structure has been widely used in aviation, aerospace and some other fields due to their characteristics which are not possessed by materials with simple substance and normal composite materials. As an important part of the honeycomb sandwich structure, it's necessary to test the mechanical properties and get performance parameters (such as modulus and ratio of transverse strain to longitudinal strain)of honeycomb cores. Because honeycomb cores are mainly composed by hollow areas and traditional electrometry limited by it, it's difficult to test them. However, at present experiment research is mainly on the whole honeycomb sandwich structure, few related research has been searched about experiment research on mechanical properties of honeycomb core.According to the characteristic of honeycomb cores, non-contact image measurement technology——corner detection method was first applied in testing of mechanical properties of honeycomb cores in the paper.The paper did research on the digital image processing of the acquisited images based on the designed image measurement system. According to the structure characteristic of honeycomb cores, corner detection was discussed emphatically. Meanwhile, subpixel detection algorithm was applied to improve the precision of the measurement.We tested aluminum and aramid paper honeycomb cores in different sizes in the whole tensile process. In-plane modulus and poisson ratio in linear elastic stage of the two materials were calculated according to the result of corner detection. Results of aluminum honeycomb cores were compared with the caculated values according to the theory on"Y"honeycomb core equivalent models. Factors affecting the result of the experiment and what can be improved were analyzed.The paper provided experiment data with reference value for the theoretical calculation and was also a new attempt to the measurement method and technology applying in the test of this kind of material with particular structure.