Nondestructive measurement of layer thickness in water-assisted coinjection-molded product by ultrasonic technology

摘要

Layer thickness is an important factor in judging the quality of a water-assisted coinjection molding (WACIM) part. Here, a novel nondestructive method for measuring layer thickness via ultrasonic technology is proposed. The reflected signals from the interface of a WACIM part were measured by an immersed pulse-echo method and calculated using a transfer function of the medium. Two objective functions were employed to describe the nonsimilarity between the measured signals and the calculated signals. By solving a multiobjective optimization problem, the optimum parameter was obtained and used to calculate the thickness of each layer in a WACIM part. The proposed method was employed to measure the layer thickness of WACIM specimens with different cross sections along the flow direction. Experimental results showed that the proposed method can correctly measure the variation in layer thickness of each layer of a WACIM part. The proposed method has broad application prospects in nondestructively measuring the layer thickness of polymeric parts. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46540.