Ballistic gel fish model with impact sensing
A fish model to replace the use of live fish in hydroelectric studies is provided. The fish model is cast from ballistic gel to include the density, dimensions, and weight distribution of a selected species of living fish. The fish model is formed by additively manufacturing a mold based on a three-dimensional scan of an actual fish. The mold is then used to mass produce fish models for force measurement testing at various blade speeds, thickness, and impact angles. Each fish model includes a surrogate skin and an internal sensor for strike force measurements. Optional additional sensors include strain gauges, temperature probes, pressure probes, and load sensors, for example.
1. A method for manufacturing a fish model, the method comprising:
performing a surface scan of a fish specimen to obtain a digital object model of the fish specimen;
additively manufacturing a mold based on the digital object model of the fish specimen, the mold defining a mold cavity;
joining a plurality of impact sensors to a filament, the plurality of impact sensors being serially spaced apart from each other along the filament;
positioning the filament and the impact sensors within the mold cavity, the filament being disposed in a lengthwise direction within the mold cavity;
injecting a ballistic gelatin into the mold cavity to overcoat the filament and the plurality of impact sensors contained within the mold cavity;
allowing the ballistic gelatin to cure within the mold cavity, thereby resulting in a fish model containing the plurality of impact sensors that are serially spaced apart from each other between an anterior region of the fish model and a posterior region of the fish model; and
removing the fish model from the mold cavity after curing of the fish model, the plurality of impact sensors being fully encapsulated within the fish model for strike force measurement at a plurality of interior locations within the fish model.
2. The method of claim 1 , wherein each of the plurality of impact sensors comprise an accelerometer.
3. The method of claim 1 , further including applying a surrogate skin to an exterior of the fish model after removing the fish model from the mold cavity.
4. The method of claim 3 , wherein applying the surrogate skin includes dip-coating or spray-coating a thermoplastic resin onto the fish model.
5. The method of claim 3 , wherein applying the surrogate skin includes applying a plurality of layers of a thermoplastic resin onto the fish model.
6. The method of claim 1 , wherein the ballistic gelatin, when cured, provides a Shore durometer of between 20 and 60.
7. The method of claim 1 , further including positioning at least one of a strain gauge, temperature probe, pressure probe, and load sensor within the mold cavity for encapsulation within the fish model.
8. A fish model for strike force measurement, the fish model comprising:
a plurality of impact sensors encapsulated within a fish-shaped body of ballistic gelatin, the plurality of impact sensors being joined to a filament that extends in a lengthwise direction between an anterior region and a posterior region of the fish model, the plurality of impact sensors being serially spaced apart from each other such that the plurality of impact sensors provide strike force measurements at a plurality of interior locations of the fish model; and
a synthetic skin comprising at least one thermoplastic coating on the ballistic gelatin.
9. The fish model of claim 8 , wherein the plurality of impact sensors comprise a plurality of accelerometers.
10. The fish model of claim 8 , wherein the thermoplastic coating includes a plurality of layers of a thermoplastic resin on an exterior of the fish-shaped body.
11. The fish model of claim 8 , further including at least one of a strain gauge, temperature probe, pressure probe, and load sensor encapsulated within the fish model.