Dynamic Modeling and Analysis of Composite Rotor Blades under Low-Velocity Impact Loads

The motivation for this work is the reduction of service and repair costs of composite rotorcraft blades through systematic understanding and prediction of actual field damages. So, the main objective is to develop robust and efficient modeling capabilities for dynamic analysis of typical composite main and tail rotor blades which are commonly subjected to low-velocity impact loads. This study covers, in detail, a proposed multi-scale concept of analysis, efficient computational implementation of dynamic finite element analysis, and representation of expected damage mechanisms in the composite skin, honeycomb core and the interface between them. A systematic parametric study is performed to understand the effects of the load conditions and the material properties of the honeycomb core, the composite skin and the interface on the risk of damage initiation and growth in composite blades. A preliminary experimental validation of the developed impact solutions is conducted for flat sandwich coupons, considered as an idealized representation of the blade pocket areas. A good correlation between the measured and independently predicted response is demonstrated. The generated results can help to reduce the potential over-conservatism in the existing blade repair techniques.