Electric time-domain reflectometry distributed flow sensor

Liquid composite molding (LCM) has become an important processing technique to manufacture high-performance composite parts. The sensing of the process parameters, such as resin fill of the porous material, are key to improve repeatability, maximize quality and minimize cost. This paper describes a distributed flow sensor, which considerably decreases tooling integration costs and improves spatial resolution by allowing sensing of hundreds of sensing elements with a single input/output port. The transmission line sensor is virtually divided into a large number of small discrete transmission lines treated as a long array of sensing elements. Piecewise sensing is achieved by electric time-domain reflectometry and inversion of a non-uniform transmission line model. The paper describes the distributed sensing approach, experimentally validates distributed sensing in a LCM setup, and analyzes critical sensor parameters.