SAE AS6999

This document describes methods for measuring dynamic forces, pressures, and projectile fragment distribution patterns during an impact between a soft or frangible projectile and a rigid flat inclined surface. It also describes the hardware, setup, and instrumentation required. In this test method, a soft body projectile impacts a rigid plate inclined at a specified angle to the direction of flight. The rigid target plate is backed up by a rigid structure, and sandwiched between the plate and the structure are force sensors to record reaction loads. Optionally, pressure transducers may be embedded in the target plate to record the pressure-time history of the impact. The target plate shall be sufficiently large so that the projectile flows across the surface without passing behind the plane of the plate impact surface, therefore capturing all of the impact load. A projectile fragment collector system for capturing projectile fragments is also described, along with a method for characterizing the projectile dispersion pattern after impact. This test is intended for measuring the transient forces and pressures generated by the projectile when it impacts the plate. Projectile breakup pattern data may also be captured during this test. The projectile material shall be low modulus and low strength (soft) compared with the target plate material. Impact stresses generated in the plate must be lower than the yield strength of the plate material so that all deformations in the plate are elastic. The values stated in either SI units or inch-pound units are considered separate standards. The values stated in each system may not be exactly equivalent; therefore, each system must be considered as independent. This standard does not address all of the safety concerns associated with its use. It is the responsibility of each user of this standard to ensure that any safety issues are properly addressed. Measurement of impact forces by soft projectiles is important in understanding how soft projectiles respond and how the forces are transmitted into the impacted structure in highly dynamic impact events. This method is recommended for recording force and pressure data to characterize the projectile response on inclined surfaces. Data captured can be used to compare the response of physical simulants, proposed to replace real birds in bird strike testing, to real bird impact responses. This method is also useful for generation of data for validation of computational material models for soft or frangible objects such as ice, soft polymers, and materials used to simulate birds for aircraft bird strike testing.