Comparing Predicted and Measured Accelerations from a Simple Drop Test Experiment

The objective of this paper is to present the results from a series of simple drop test experiments compared with the equivalent FEA models. This is to demonstrate the validity of utilising predicted acceleration-time histories and understand the associated signal processing to determine the accuracy of the data. Measured accelerations are used in drop testing and crashworthiness to validate FEA models. It is a common practice to predict velocity or displacement-time histories with FEA, which can be differentiated to obtain accelerations for design calculations. The work also considered predicted accelerations based upon the drop height and the length of deformation experienced, without requiring nodal outputs requested in the pre-processing stage. In order to simplify the tests, a small section of standard stainless steel 304 pipe was located on a stationary plate, fitted with a load cell, and a rigid cylindrical impactor with pre-defined mass dropped from a known height above the sample. An accelerometer was attached to the top of the impactor to produce acceleration-time history data. The tests were reproduced using LS-Dyna R7.1.2 FEA software to extract acceleration-time histories from four nodal outputs and reaction force-time histories from a simulated rigid wall in order to compare these with the results from the physical tests.