Use of Ultrasonic Lamb Waves for In-Process Porosity Inspection of the Pultrusion Process: Theoretical Velocity Calculations

Substantial growth potential for composite materials exists in the private sector, where high-volume, low-cost production is required. Post processing inspection can represent a significant percentage of the cost of composite products. Alternate ways of assuring quality must be examined. In-process inspection can be effectively applied to continuous composite manufacturing techniques such as the pultrusion process. Recent research efforts at the Center for Composite Materials has focused on ways of evaluating pultruded composites on-line by using ultrasonic non-destructive evaluation (NDE) techniques. The most accurate method to date is based upon Lamb wave velocity measurements. This paper focuses on the theoretical analysis used to predict the Lamb wave velocities and compares the results with experimental measurements.