EFFECT OF MICROCRACKS ON MECHANICAL PROPERTY OF COMPOSITE HONEYCOMB SANDWICH STRUCTURE SUBJECTED TO THERMAL CYCLING

摘要

Mechanical properties of composite honeycomb sandwich structure, consisting of Kevlar honeycomb core and CFRP laminates, subjected to thermal cycling were studied. The material under study is used for spacecraft structural application. The material undergoes thermal cycling in space as a result of spacecraft orbiting the earth, during which the temperature can reach as high as ± 185 ℃. Test plan was developed to subject the composite structure to the above mentioned thermal conditions. To achieve lower temperature the samples were dipped in liquid nitrogen. To get to higher temperature, the samples were placed in a convection oven. The samples were then inspected for microcrack formation at their cross sections. The observation was done on two perpendicular sides, ribbon side meaning the cut was made parallel to the honeycomb core ribbon direction and transverse side where cut was made perpendicular to the ribbon direction. It was observed that the majority of microcracks are formed at the interface of the adhesive and the composite facesheets Flatwise tensile test was conducted after subsequent set of cycles, to make a correlation between number of thermal cycles and mechanical property.