Research On Damage Resistance Of Laminated Composites Subjected To Concentrated Quasi-static Indentation

Quasi-static indentation tests on composite laminates have been conducted to examine the failure mechanisms of different composite laminates under static indentation and understand the efficiency of damage resistance.It is difficult to estimate indent depth in theory. This paper presents two methods to estimate the relationship between dent depth and contact force, respectivelyβamend method and deflection compensate method, which are developed by using a clear geometrical relation to express indent, incursion profile and deflection difference. It is shown by the difference of the estimation and tests result that these two methods can well estimate indent depth of laminates both in little and large indent situation.In addition, the research on the effect of boundary conditions to indent depth has been conducted in this paper. The results indicate that the boundary conditions have negligible effect on indent depth estimate, and the stiffness of laminates in contacting area has the major effect on the indent depth.Comparison between quasi-static indentation and low-velocity impact tests has been conducted in this paper at last. In accordance with energy balance principle, the dent depth vs. peak contact force under impact curve, which is derived from the dent depth vs. impact energy curve, is similar with the dent depth vs. indentation force curve with an evident transition. This similarity proves that it is effective to use the quasi-static method to simulate low-velocity impact response of composite laminates.