LOCATING MANUFACTURING AND STRUCTURAL IRREGULARITIES IN LARGE SCALE COMPOSITE SANDWICH STRUCTURES

摘要

Composites are gaining increased use as a structural material for Navy applications. Applications such as the masts for LPD-17 class ship, the Joint Modular Leighter System (JMLS) and the sail for the Virginia Class Submarine have planar area of composite structure that are thousands of square feet. With structures of this size, methodologies of nondestructive inspection to ensure their structural integrity become very important. In addition, although inspection techniques are available which can be readily implemented in a laboratory setting, few exist which can be used for in-service inspection that is required for these structures. This paper presents a broadband vibration-based Structural Integrity and Damage Evaluation Routine (SIDER) that has been shown to be sensitive and repeatablefor the determination of the structural integrity of large scale sandwich core structures. In addition, it has been used to determine the long term degradation of an all composite road bridge. The routine looks for features in complex curvature operating shape. It was developed to assist in the inspection of deep-section structures that cannot be inspected using more conventional methods. The paper presents a theoretical outline of the procedure and inspection results from a an all-composite road bridge in Glasgow, Delaware, a composite bridge deck structure in Ohio, and a large scale corner burn test.