Design and Instrumentation of an In-house Drop Tower for Low Velocity Impact Testing of Composites and Metals

This study presents the design and development of a customized, in-house drop-tower impact-testing facility for investigating the effects of low-velocity impact (LVI) on composites and metals using a spherical indenter. Eighteen samples were tested under various impact conditions with various energy levels. Four distinct types of mounting blocks with a spherical indenter were designed, and LVI tests were conducted. The influence of tightening, impactor mass, and mounting block design on the force response was systematically examined. Force responses were recorded using a piezoelectric force sensor, a charge amplifier, and an oscilloscope. Additionally, high-speed imaging with digital image correlation (DIC) analysis was included to validate the structural rigidity of the systems. Results from the in-house facility were compared with those from a commercially available drop tower for validation. Following multiple iterations of design, experimentation, and validation, the in-house system achieved an accuracy level closely matching that of the commercial setup. We will make the design of the drop tower publicly available to facilitate the democratization of the mechanical testing initiative.