Speaker
Description
The differences between 8 3D-printed bridges, which were fabricated using various 3D-printing technologies, materials and internal structures, were explored and compared to the original wooden cello bridge. Input admittance measurements were used to investigate how the different bridges affect the resonance characteristics of the bridge–body system. These measurements were obtained using an automated impact hammer system mounted on a robotic arm. This allowed the fragile impact hammer to be moved to a safe position while the bridge was being interchanged, and ensured highly reproducible excitations. The response was captured using two accelerometers attached to either side of the bridge under test. A laser and camera system assisted with the repositioning of the bridges and accelerometers. During six measurement sessions all 9 bridges were tested, with 20 impact measurements per bridge. The high number of repetitions and exchange sequences was intended to identify the actual influence of the material on the measurements and to exclude differences caused by repositioning on the instrument. Input admittance, coherence and speed of sound within the tested bridges are compared amongst materials. The findings provide a foundation for the further development of a 3D-printed sensor-equipped bridge.