Acousto-Ultrasonic Defect Detectionin Composite Armor Material

Advanced armor composites offer lightweight designs using unique materials, laminated together, to provide the same protection as its metal counterpart. Using these different material designs also means dealing with different types of defects. Delaminations between the different layers of materials are the most commonly encountered defects which need to be found and characterized during normal inspection procedures. Inspection of this material to find delaminations, with conventional, high frequency, ultrasonic methods is not possible and justifies the development of new inspection methods. One possible solution is to study oblique incidence waves that are reflected from delaminations, and develop an Acousto-Ultrasonic approach. Preliminary studies have shown that measurements made below 300 kHz with the incidence angle varying between -20¿ and +20¿, yield promising results. This study will demonstrate the feasibility of the proposed approach and ultimately deliver a probe/system concept that will form the basis of a prototype inspection instrument. BENEFITS: It is anticipated that the results of this study will lead to the development of a unique inspection instrument useful for detecting delaminations and other defects in thick, multi-layered composite. It will be effective as an acceptance tool for newly fabricated material and for in-service fleld inspection where only one surface is available for measurements. Besides being useful for lightweight armor composites, we see its use being extended to the automotive industry where composites will eventually find its way into the design of primary load carrying structure. In addition, we believe that other markets will benefit from this type of instrument such as in the Aerospace industry for both fixed and rotary wing aircraft fabricated from composites as well as future bridge structures that will be built from composite materials. There is already a need for such a device for Natural Gas Vehicles (NGV) for the inspection and detection of delaminations in Types II, III and IV cylinders.